/'BERKELEY' LIBRARY OF \CAUfORNIA EARTN SCIENCES LIBRARY ^-^^-^-ojc^c^c^-i^s--^ >- t ^y MANUAL OF GEOLOGY TREATING OF THE PRINCIPLES OF THE SCIENCE WITH SPECIAL REFERENCE TO AMERICAN GEOLOGICAL HISTORY BY JAMES D. DANA PROFESSOR EMERITUS OF GEOLOGY AND MINERALOGY IN YALE UNIVERSITY: AUTHOR OP A SYSTEM OF MINERALOGY; CORALS AND CORAL ISLANDS; VOLCANOES; REPORTS OF WILKES'S EXPLORING EXPEDITION, ON GEOLOGY, ON ZOOPHYTES, AND ON CRUSTACEA, ETC. "Speak to the Earth and it shall teach thee" ILLUSTRATED BY OVER FIFTEEN HUNDRED AND SEVENTY-FIVE FIGURES IN THE TEXT, AND TWO DOUBLE-PAGE MAPS FOURTH EDITION NEW YORK-:. CINCINNATI-:. CHICAGO AMERICAN BOOK COMPANY LONDON: TRtfBNER AND CO. 1896 MATTHEW LIBRARX COPYRIGHT, 1894. BY JAMES D. DANA w. p. 3 PREFACE. IN the preparation of the new edition of this Manual, the work has been wholly rewritten. North American Geological History is still, how- ever, its chief subject. The time divisions in this history, based on the ascertained subdivisions of the formations, were first brought out in my Address before the meeting of the American Association at Providence in 1855 ; and in 1863, the " continuous history " appeared in the first edition of this Manual, written up ironi the State reports and other geological pub- lications. The idea, long before recognized, that all observations on the rocks, however local, bore directly on the stages in the growth of the Con- tinent derives universal importance from the recognition of North America as the world's type-continent the only continent that gives, in a full and simple way, the fundamental principles of continental development. Since 1863, when the first edition of this work was published, investi- gation, through the geological workers of the United States, Canada, and Mexico, has been extended over nearly all parts of the continent, so that its history admits of being written out with much fullness. The Government Expeditions over the Rocky Mountain region, under F. V. HAYDEN, CLAR- ENCE KING, CAPTAIN WHEELER and others, and earlier, those especially of the Pacific Railroad Explorations, and the Mexican Boundary Commission, were large contributors to this result ; and also, since 1879, the able corps of the United States Geological Survey. As the rewritten book shows, new principles, new theories, and widely diverse opinions on various subjects are among the later contributions, along with a profusion of new facts relating to all departments of the science. The Cambrian formation has been traced through a large part of the continent, and the number of its fossils has been increased, chiefly by C. D. WALCOTT, from a few to hundreds. The Appalachian Mountain structure has been shown by CLARENCE KING, Dr. G. M. DAWSON, and R. G. MCDON- NELL to have been repeated in the great post-Cretaceous mountain-making of the Rocky Mountain region. The Reptiles, Birds, and Mammals of the Mesozoic and Tertiary have continued coming from the rocks until the species recognized much outnumber those of any other continent. The canons and other results of erosion in the west have thrown new light, through their investigators, on the work of the waters. Besides, the science of 4 PREFACE. petrology lias elucidated ^inuch of the obscure in the constitution, relations, and, -origin: cf :rocksj ^ t ,\ Moreover, America; ^froni early in the century, has been receiving instruction through the development and parallel progress of the Science in Europe and Other lands. The first edition of this Manual owed much to the advice of the able paleontologist, F. B. MEEK, and also to his skill as a draftsman; and the work still bears prominent evidence of his knowledge, judgment, and scru- pulous exactness, traits which give a permanent value to all the results of his too soon ended labors. In this new edition, the Paleozoic paleontology is largely indebted to PROFESSOR C. E. BEECHER and PROFESSOR H. S. WILLIAMS ; the Jurassic, of western America, to PROFESSOR A. HYATT ; the Cretaceous, to PROFESSOR HYATT, MR. T. W. STANTON, MR. E. P. WHITFIELD, and PROFESSOR R. T. HILL ; and the Tertiary, as regards the Invertebrates, to PROFESSOR G. D. HARRIS. With respect to the Vertebrates of the Jurassic, Cretaceous, and Tertiary, very valuable aid has been received from PROFESSOR MARSH, and also in the part on Tertiary Mammals from PROFESSOR W. B. SCOTT. The account of the arrangement and distribution of the Jurassic and Cretaceous rocks of western America was prepared with the assistance of MR. J. S. DILLER ; and that with regard to the marine Tertiary of the country was chiefly written for its place by PROFESSOR HARRIS. I am further indebted to PROFESSOR A. E. VERRILL for his revision of the pages on the Animal Kingdom. Moreover, the replies to requests for information have placed me under obligation to almost all the geologists of the Continent, those of Canada as well as the United States, and especially to SIR WILLIAM DAWSON, MR. A. R. C. SELWYN, DR. G. M. DAWSON, MR. CLARENCE KING, MR. C. D. WALCOTT, PROFESSOR N. S. SHALER, PROFESSOR S. H. SCUDDER, MR. FRANK LEVERETT, PROFESSOR R. T. HILL, PROFESSOR W. UPHAM, PRO- FESSOR G. F. WRIGHT, PROFESSOR J. J. STEVENSON, MR. WM. H. BALL, DR. C. A. WHITE, and PROFESSOR J. P. IDDINGS. Throughout this volume, the dates of papers containing cited facts or views are often stated. If a condensed bibliography, containing in brief form the titles of the most important geological and paleontological works and papers, arranged under the year of publication, were accessible to the student, these dates would be a sufficient means of reference. Without such a Bibliography they may serve as a help in consulting, besides Reports of Geological Surveys, the serial scientific publications. It is best to com- mence the search with the periodical containing the most geological papers, notes, and book notices, and follow on with the others. The American Journal of Science commenced in 1818; the American Naturalist, in 1868; the American Geologist, in 1888; the Bulletin of the American Geological Society, in 1890; the Journal of Geology, Chicago, in 1893. Then refer to the Proceedings and Memoirs of American Scientific Soci- PREFACE. 5 eties or Academies, in the following order: Academy of Natural Sciences of Philadelphia ; American Philosophical Society, Philadelphia ; Society of Natural History, Boston ; American Academy, Boston ; Lyceum of Natural History, and later, Academy of Sciences, New York; and so on, not over- looking the Reports of the American Association for the Advancement of Science. The foreign serial works of most importance to the geologist are the Journal of the Geological Society of London ; the Geological Magazine, London ; Bulletin of the Geological Society of France ; " Comptes Eendus " of the Academy of Sciences, Paris ; Jahrbuch fur Mineralogie, Geologic und Palaeontologie, Stuttgart; Zeitschrift der deutschen geologischen Gesell- schaft, Berlin ; Jahrbuch der k.-k. geologischen Eeichsanstalt, Vienna. For foreign facts and views I am largely indebted to the able English works of SIR ARCHIBALD GEIKIE, PROFESSOR PRESTWICH, and PROFESSORS ETHERIDGE and SEELEY, the very full Traite de Geologic of PROFESSOR A. DE LAPPARENT, and the Elemente der Geologic of DR. CREDNER. As the volume is necessarily larger than that of the edition of 1880, partly through more text, but also through a greater profusion of illustra- tions, the instructor may find it convenient, in his use of the Historical part, to take up successively its two great subjects, the geological and physical history of the continents, and the history of its life. JAMES D. DANA. NEW HAVEN, CONN., January, 1895. TABLE OF CONTENTS. INTRODUCTION. Relations of the Science of Geology Subdivisions of Geology .... PAGE 9 13 PART I. Physiographic Geology. 1. The Earth's General Contour and Surface Subdivisions .... 15 2. System in the Reliefs of the Land . 30 3. System in the Courses of the Earth's Feature Lines 35 4. Oceanic and Atmospheric Move- ments and Temperature ... 42 5. Geographical Distribution of Plants and Animals 52 PART II. Structural Geology. 1. Rocks: their Constituents and Kinds 61 2. Terranes : their Constitution, Char- acteristics, Positions, and Ar- rangement 89 PART III. Dynamical Geology. Agencies and General Subdivisions . 117 1. Chemical Work 118 2. Life: its Mechanical Work and Rock Contributions 140 General Remarks on Rock-making 141 Protective and Other Beneficial Effects 155 Transporting Effects 156 Destructive Effects 157 3. The Atmosphere as a Mechanical Agent 158 4. Water as a Mechanical Agent . . 166 Fresh Waters : Rivers and Lakes . 171 The Ocean 209 Freezing and Frozen Water: Glaciers, Icebergs 230 5. Heat .......... 253 1. Sources of Heat ...... 253 2. Expansion and Contraction . . 259- 3. Igneous Action and its Results 265 Volcanoes ........ 267 Non-volcanic Igneous Eruptions 297 Thermal Waters, Geysers . . 305 4. Metamorphism ...... 30& 5. Mineral Veins, Lodes, Local Ore Deposits ..... . . 327 6. Hypogeic Work: Earth-shaping, Mountain-making .... 345 1. Characteristics of Disturbed Regions and Mountains . . 351 2. Subordinate Effects attending Orographic Movements : Ef- fects from Pressure, Earth- quakes ....... 369 3. Originof tli e Earth's Form and Features : Orogenic Work, Epeirogenic Work . . . 376 PART IV. Historical Geology. Subdivisions in Geological History . 397 Review of the System of Life . . . 413 1. Animal Kingdom ...... 414 2. Vegetable Kingdom ..... 434 I. ARCHAEAN TIME . 1. Subdivisions: Rocks 2. Life . 440 445 453 II. PALEOZOIC TIME .... 460 I. Cambrian Era 462 1. North American .... 464 1. Lower Cambrian Period 470' 2. Middle Cambrian Period 474 3. Upper Cambrian Period 476 TABLE OF CONTENTS. 2. Foreign 480 3. Geographical and Physical Conditions and Progress . 483 II. Lower Silurian Era .... 489 1. North American .... 489 2. European . . .... 517 3. General Observations : Rocks ; Climate ; Biologi- cal Progress 524 4. Upturning at the close of the Lower Silurian ... . 526 III. Upper Silurian Era .... 535 1. North American .... 535 1. Niagara Period ... 538 2. Onondaga Period . . . 552 3. Lower Helderberg Period 558 2. Foreign 563 3. General Observations : Geo- logical ; Geographical ; Biological 670 IV. Devonian Era 675 1. North American .... 575 1. Oriskany Period . . . 577 2. Corniferous Period . . 679 3. Hamilton Period ... 592 4. Chemung Period' . . . 602 2. Foreign 622 3. General Observations : Geo- logical ; Geographical . . 628 4. Upturning at the close of the Devonian .... 630 V. Carbonic Era 631 1. North American .... 633 1. Subcarboniferous Period 636 2. Carboniferous Period . 647 3. Permian Period ... 660 2. Foreign 693 3. General Observations : Geo- logical and Geographical ; Meteorological ; Forma- tion of Coal .... 708 General Observations on Paleozoic Time . 714 Post-Paleozoic, or Appalachian, Revolution 728 Topographic Changes in the Indian Ocean : Gondwana Land . . . 737 III. MESOZOIC TIME 738 1. American Triassic and Jurassic Period 739 2. Foreign Triassic and Jurassic . 768 3. General Observations : Conti- nental Comparisons; Cli- mate ; Biological Changes ; Upturnings and Mountain- making 791 4. American Cretaceous Period . 812 5. Foreign 856 6. General Observations: Geologi- cal ; Geographical ; Biolog- ical; Gondwana Land . . 867 Post-Mesozoic Revolution . . . 874 IV. CENOZOIC TIME 879 I. Tertiary Era 879 1. North American .... 880 2. Foreign 919 3. General Observations : Bio- logical ; Orogenic and Epeirogenic ; Climate . 928 II. Quaternary Era 940 1. Glacial Period ..... 943 1. American 943 2. Foreign 975 3. Cause of Glacial Climate 978 2. Champlain Period ... 981 1. American 98.1 2. Foreign 996 3. Pleistocene Life .... 997 4. Recent Period 1012 General Observations : Biolog- ical ; Antarctic Continent ; Epeirogenic 1016 General Observations on Geological History 1023 Geological Time 1023 Climate ; the Earth's Development . 1026 Progress in the Earth's Life .... 1028 ABBREVIATIONS. Ag.-L. B. E. Billings. Barr. J. Barrande. Beyr. E. Bey rich. Blum. J. F. Blumenbach. Blv. D. de BlainviUe. Br. H. G. Bronn. Brngt. Brongniart. Brod. Broderip. Bu. L. von Buch. Con. T. A. Conrad. D. J. D. Dana. Dalm. J. W. Dalman. Dav. T. Davidson. Def r. Def ranee. Desh. G. P. Deshayes. Dawson, Dn. Sir Wm. Daw- son. D'Orb. Alcide d'Orbigny. E. & H. Edwards & Haime. Ehr. Ch. G. Ehrenberg. Eich. E. Eichwald. Emmr. H. F. Emmrich. Fabr. Fabricius. Falc. H. Falconer. Flem. J. Fleming. Fer. Ferussac. G. & H. Gabb & Horn. Gem. Geinitz. Gld. Gould. Gm. Gmelin. Gopp. H. R. Goppert. Goldf. Goldfuss. H. J. Hall. H. & M. Hall & Meek. Hald. S. S. Haldeman. Hising. W. Hisinger. Hk. E. Hitchcock. Hux. T.H.Huxley. Kon. L. de Koninck. L. J. Leidy. L. & H. Lindley & Hutton. Lam . Lamarck . Linn. Linnaeus. Lmx. Lamouroux. Lsqx., Lx. L. Lesquereux. Lye. Lycett. M. F. B. Meek. Mant. G. Mantell. Mey . H. von Meyer. Mh. O.C. Marsh. Montf. Denys de Montfort. Morr. Morris. Mort. S. G. Morton. Mull. Mtiller. Murch. R. I. Murchison. N. & P. Norwood & Pratten. Woodw. J. Woodward. N. & W. Newberry & Worth- en. Newb. J. S. Newberry. O. & N. Owen & Norwood. Ow. R. Owen (London). Pack. A. S. Packard. Phill. J. Phillips. Plien. T. Plieninger. Portl. J. E. Portlock. R. F. Romer. Rem. A. RemoncL S. J. W. Salter. Saff. J. M.Safford. Sc. S. H. Scudder. Schafh. Schafhautl. Schlot. E. F. von Schlotheim. Schp. W. P. Schimper. Sedg. A. Sedgwick. Shum. B. F. Shumard. Sow. Sowerby. St. Stokes. Sternb. K. von Sternberg. Suck. Suckow. Ung. Unger. Van. Vanuxem. Vern. E. de Verneuil. INTRODUCTION. Kingdoms of nature. SCIENCE, in her survey of the earth, has recog- nized three kingdoms of nature, the animal, the vegetable, and the inorganic ; or, naming them from the forms characteristic of each, the ANIMAL KINGDOM, the PLANT KINGDOM, and the CRYSTAL KINGDOM. An individual in either kingdom has its systematic mode of formation or growth. The plant or animal, (1) endowed with life, (2) commences from a germ, (3) grows by means of imbibed nutriment, and (4) passes through a series of changes and gradual development to the adult state, when (5) it evolves new seeds or germs, and (6) afterward continues on to death and dissolution. It has, hence, its cycle of growth and reproduction, and cycle follows cycle in indefinite continuance. The crystal is (1) a lifeless object, and has a simpler history ; it (2) begins in a nucleal molecule or particle ; (3) it enlarges by external addition or accretion alone ; and (4) there is, hence, no proper development, as the crystal is perfect, however minute ; (5) it ends in simply existing, and not in reproducing ; and, (6) being lifeless, there is no proper death or necessary dissolution. Such are the individualities in the great kingdoms of nature displayed upon the earth. But the earth also, according to Geology, has been brought to its present condition through a series of changes or progressive formations, and from a state as utterly featureless as a germ. Moreover, like any plant or animal, it has its special systems of interior and exterior structure, and of interior and exterior conditions, movements, and changes ; and, although Infinite Mind has guided all events toward the great end, a world for mind, the earth has, under this guidance and appointed law, passed through a regular course of history or growth. Having, therefore, as a sphere, its comprehen- sive system of growth, it is a unit or individuality, not, indeed, in either of the three kingdoms of nature which have been mentioned, but in a wider, a WORLD KINGDOM. Every sphere in space must have had a related system of growth, and all are, in fact, individualities in this Kingdom of Worlds. 9 10 INTRODUCTION. Geology treats of the earth in this grand relation. It is as much removec}: from Mineralogy as from Botany and Zoology. It uses all these depart- ments; for the species under them are the objects which make up the earth and enter into geological history. The science of minerals is more immediately important to the geologist, because aggregations of minerals constitute rocks, or the plastic material in which the records of the past were made. The earth, regarded as such an individuality in a world kingdom, has not only its comprehensive system of growth, in which strata have been added to strata, continents and seas defined, mountains reared, and valleys, rivers,, and plains formed, all in orderly plan, but also a system of currents in its oceans and atmosphere, the earth's circulating-system ; its equally world- wide system in the distribution of heat, light, moisture, and magnetism, and of plants and animals; its system of secular variations (daily, annual, etc.) in its climate and all meteorological phenomena. In these characteristics the sphere before us is an individual, as much as a dog, or a tree ; and, to arrive at any correct views on these subjects, the world must be regarded in this capacity. The distribution of man and nations, and of all productions that pertain to man's welfare, comes in under the same grand relation ; for,, in helping to carry forward man's progress as a race, the sphere is working out its final purpose. There are, therefore, Three departments of science, arising out of this individual capacity of the earth. I. GEOLOGY, which treats of (1) the earth's structure, and (2) its system of development, the latter including its progress in rocks, lands, seas, mountains, etc. ; its progress in all physical conditions, as heat, moisture, etc. ; its progress in life, or its vegetable and animal tribes. II. PHYSIOGRAPHY, which begins where Geology ends, that is, with the adult or finished earth, and treats (1) of the earth's final surface- arrangements (as to its features, climates, magnetism, life, etc.); and (2) of its system of physical movements or changes (as atmospheric and oceanic currents, and other secular variations in heat, moisture, magnetism, etc.). III. THE EARTH WITH REFERENCE TO MAN (including ordinary Geog- raphy): (1) the distribution of races or nations, and of all productions or conditions bearing on the welfare of man or nations ; and (2) the progressive changes of races and nations. The first of these departments considers the structure and growth of the earth ; the second, its features and world-wide activities in its finished state ; the third, the fulfillment of its purpose in man. Relation of the earth to the universe. While recognizing the earth as a sphere in a world kingdom, it is also important to observe that it holds a very subordinate position in the system of the heavens. It is one of the smaller satellites of the sun, its size about ^ooooo that ^ the sun * Ami the planetary system to which it belongs, although 3,000,000,000 of miles in radius, is but one among myriads, the nearest star being 7000 times INTRODUCTION. 11 farther off than Neptune. Thus it appears that the earth is a very small object in the universe. Hence we naturally conclude that it is a dependent part of the solar system ; that, as a satellite of the sun, in conjunction with other planets, it could no more have existed before the sun, or our planetary system before the universe of which it is a part, than the hand before the body which it obediently attends. Although thus diminutive, the laws of the earth are the laws of the universe. One of the fundamental laws of matter is gravitation; and this we trace not only through our planetary system, but among the fixed stars, and thus know that one law pervades the universe. The rays of light which come in from the remote limits of space are a visible declaration of unity; for this light depends on molecular vibra- tions, that is, the ultimate constitution and mode of action of matter ; and, by the identity of its principles or laws, whatever its source, it proves the essential identity of the molecules of matter. Meteoric stones are specimens of celestial bodies occasionally reaching us from the heavens. They exemplify the same chemical and crystal- lographic laws as the rocks of the earth, and have afforded no new element or principle of any kind. The moon presents to the telescope a surface covered with the craters of volcanoes, having forms that are well illustrated by some of the earth's volcanoes, although of immense size. The principles exemplified on the earth are but repeated in her satellite. Thus, from gravitation, light, meteorites, and the earth's satellite, we learn that there is oneness of law through space. The elements may differ in different systems, but it is a difference such as exists among known elements, and even if exemplifying new laws, such laws cannot be at variance with those illustrated by nature within reach of terrestrial investi- gation. The universe, if open throughout to our explorations, would vastly expand our knowledge, and science might have a more beautiful superstruc- ture, but its basement-laws would be the same. A treatise on Celestial Mechanics printed in our printing-offices would serve for the universe. The earth, therefore, although but an atom in immensity, is immensity itself in its revelations of truth; and science, though gathered from one small sphere, is the deciphered law of all spheres. It is well to have the mind deeply imbued with this thought, before entering upon the study of the earth. It gives grandeur to science and dignity to man, and will help the geologist to apprehend the loftier charac- teristics of the last of the geological ages. Special aim of geology, and method of geological reasoning. Geology is sometimes defined as the science of the structure of the earth. But the ideas of structure and origin of structure are inseparably connected, and in all geological investigations they go together. Geology had its very begin- ning and essence in the idea that rocks were made through secondary causes ; and its great aim has ever been to study structure in order to com- 12 INTRODUCTION. prehend the earth's history. The science, therefore, is a historical science. It finds strata of sandstone, clayey rocks, and limestone, lying above one another in many successions; and, observing them in their order, it assumes, not only that the sandstones were made of sand by some slow process, clayey rocks of clay, and so on, but that the strata were successively formed; that, therefore, they belong to successive periods in the earth's past ; that, con- sequently, the lowest beds in a series were the earliest beds. It hence infers, further, that each rock indicates some facts respecting the condition of the sea or land at the time when it was formed, one condition originating sand deposits, another clay deposits, another lime, and, if the beds extend over thousands of square miles, that the several conditions prevailed uniformly to at least this same extent. The rocks are thus regarded as records of successive events in the history, indeed, as actual historical records ; and every new fact ascertained by a close study of their structure, be it but the occurrence of a pebble, or a seam of coal, or a bed of ore, or a crack, or any marking whatever, is an addition to the records, to be interpreted by careful study. Thus every rock marks an epoch in the history ; and groups of rocks, periods ; and still larger groups, eras or ages ; and so the eras which reach through geological time are represented in order by the rocks that extend from the lowest to the uppermost of the series. If, now, the great beds of rock, instead of lying in even horizontal layers, are much folded up, or lie inclined at various angles, or are broken and dislocated through hundreds or thousands of feet in depth, or are uplifted into mountains, they bear record of still other events in the great history ; and should the geologist, by careful study, learn how the great disturbance or uplifting was produced, and succeed in locating its time of occurrence among the epochs registered in the rocks, he would have inter- preted the record, and added not only a fact to the history, but also its explanation. The history is, hence, a history of the upturnings of the earth's crust, as well as of its more quiet rock-making. If, in addition, a fossil shell, or coral, or bone, or leaf, is found in one of the beds, it is a relic of some species that lived when that rock was forming ; it belongs to that epoch in the world represented by the particular rock containing it, and tells of the life of that epoch ; and, if numbers of such organic remains occur together, they enable us to people the seas or land, to our imagination, with some of the kinds of life that belonged to the ancient epoch. Moreover, as such fossils are common in a large number of the strata, from the lowest containing signs of life to the top, that is, from the oldest beds to the most recent, by studying out the characters of these remains in each, we are enabled to restore to our minds, to some extent, the popula- tion of the epochs, as they follow one another in the long series. The strata are thus not simply records of moving seas, sands, clays, and pebbles, and disturbed or uplifted strata, but also of the living beings that have in INTRODUCTION. 13 succession occupied the land and waters. The history is a history as com- plete as can be learned from the fossils of the life of the globe, as well as of its rock-formations ; and the life-history, imperfect though it be, is the great topic of Geology : it adds tenfold interest to the other records of the rocks. These examples are sufficient to explain the basis and general bearing of geological history. The method of interpreting the records rests upon the simple principle that rocks were made as they are now made, and life lived in olden time as it now lives ; and, further, the mind is forced into receiving the conclusions arrived at by its own laws of action. We observe that many of the common rock-strata consist of the same materials that make up the deposits of sand and gravel of sea-beaches or sand-flats, or of the clays or muds of the bottoms- of estuaries or the borders of rivers, and that they are arranged in beds like the modern deposits, even have, at times, ripple-marks and other evidences of the action of water or wind ; and further remark that these hard rocks differ from the loose sand, clay, or pebbly deposits simply in being consoli- dated into a rock; and, in other places, discover these sand-deposits in all states of consolidation, from the soft, movable sand, through a half-compacted condition, to the gritty sandstone. By such steps as these, the mind is borne along irresistibly to the conclusion that rocks were slowly made through common-place operations. These few examples elucidate the mode of reasoning upon which geo- logical deductions are based. In using the present in order to reveal the past, we assume that the forces in the world are essentially the same through all time; for these forces are based on the very nature of matter, and could not have changed. The ocean has always had its waves, and those waves have ever acted in the same manner. Running water on the land has ever had the same power of wear and transportation and mathematical value to its force. The- laws of chemistry, heat, electricity, and mechanics have been the same throughout time. The plan of living structures is fundamentally one, for the whole series belongs to one system, as much almost as the parts of ani animal to one body ; and the relations of life to light and heat, and to the atmosphere, have ever been the same as now. The laws of the existing: world, if perfectly known, are consequently a key to past history. SUBDIVISIONS OF GEOLOGY. (1) Like a plant or animal, the earth has its systematic external form and features, which should be reviewed. (2) Next, there are the constituents of the structure to be considered: first, their nature; second, their general arrangement. (3) Next, the successive stages in the formation of the structure, and the concurrent steps in the progress of life, through past time. 14 INTRODUCTION. (4) Next, the general plan or laws of progress in the earth and its life. , (5) Finally, there are the active forces and mechanical agencies which were the means of physical progress, spreading out and consolidating strata, raising mountains, ejecting lavas, wearing out valleys, bearing the material of the heights to the plains and oceans, enlarging the oceans, destroying life, and performing an efficient part in evolving the earth's structure and features. These topics lead to the following subdivisions of the science : I. PHYSIOGRAPHIC GEOLOGY, a general survey of the earth's surface- features. II. STRUCTURAL GEOLOGY, a description of the rock-materials in the structure of the globe, that is, of its kinds of rocks, and of their arrange- ment or positions. III. DYNAMICAL GEOLOGY, an account of the agencies or forces that have produced geological changes, and of the laws, methods, and results of their action. IV. HISTORICAL GEOLOGY, an account of the earth's geological his- tory, or the successive events or steps in the making of the rock-strata, and of the continents, seas, mountains, and valleys, in the progress of the earth's living species, and in all changes that have gone forward in the earth's development. In the study of the science, a previous knowledge of the methods of change taught in the Dynamical section is desirable in order fully to comprehend Historical geology ; and a knowledge of the actual facts and their succession given in the Historical section is desirable to understand the causes of events and methods of change. There is reason, therefore, for studying Dynamical geology before Historical as well as after it. It is here made to precede. But the last topic under it that of the formation of mountains will be best appreciated after the student is familiar with the facts presented in the Historical -section. PART I. PHYSIOGRAPHIC GEOLOGY. THE systematic arrangement in the earth's features is an indication of system in the earth's development. The orderly arrangement in the continents and oceans, island chains and mountains, is an outcome of the most fundamental movements in the forming sphere. An appreciation of tne earth's physiognomy is hence the first step toward an investigation of its laws of origin. This subject is therefore an important one to the geologist, although its facts come also within the domain of physical geography. They are the final results in geology, and thence become the arena of the physical geographer. The following are the divisions in this department : I. The earth's general contour and surface subdivisions. II. System in the reliefs or surface forms of the continental lands. III. System in the courses of the earth's feature lines. These topics are followed by a brief review of, IV. Oceanic and atmospheric movements and temperature. V. Geographical distribution of plants and animals. I. THE EARTH'S GENERAL CONTOUR AND SURFACE SUBDIVISIONS. The subjects under this head are the earth's form; the distribution of land and water ; the true outlines and features of the oceanic depression ; the subdivisions, positions, and general features of the land ; the height and kinds of surface of the continents. (1) Spheroidal form. The form of the earth is spherical, with the poles flattened, the distance from the center to the pole being about ^J^- shorter than that from the center to the equator. The length of the equatorial radius is 3963 miles, and that of the polar about 13^ miles less. The form approaches closely that of an ellipsoid of revolution. The mean density is about 5-5 times that of water, which is a little more than twice that of the two most common minerals, calcite (2-72) and quartz (2-65), and more than two thirds that of pure iron (7-75). 15 16 PHYSIOGRAPHIC GEOLOGY. The density of the moon is 3-1, or about that of basalt ; of Mercury, 6-2 ; of Venus and Mars, each. 5'2 ; of Jupiter, 1-3. The earth's atmosphere, if considered a part of the sphere, adds several hundred miles to its diameter. Its actual limit is not ascertained j but evi- dence from meteorites places it at least 200 miles above the earth's surface. (2) General subdivisions of the earth's surface. Proportion of land and water. In the surface of the sphere there are about 73% of water to 27% of dry land. The proportion of land north of the equator is nearly three times as great as that south. The zone containing the largest proportion of land is the north temperate, the area equaling that of the water ; while it is only one third that of the water in the torrid zone, and hardly one tenth (^) in the south temperate. Out of the 196,900,000 of square miles which make up the entire surface of the globe, 144,155,000 are water and 52,745,000 land. In the northern hemisphere the land covers 38,780,000 square miles, and the water 59,670,000; in the southern, the land 13,965,000 square miles, the water 84,485,000. Land in one hemisphere. If a globe be cut through the center by a plane intersecting the meridian of 175 E. at the parallel of 40 N., one of the hemispheres thus made, the northern, will contain nearly all the land of the globe, and the other be almost wholly water. The annexed map repre- sents the two hemispheres. 1. 16JLJJL2-165 The pole of the land-hemisphere in this map is in the western half of the British Channel ; and, if this part, on a common globe, be placed in the zenith, under the brass meridian, the horizon-circle will then mark the line of division between the two hemispheres. Of the 98,450,000 square miles of surface in each hemisphere, there are about 45,000,000 of land in the land-hemisphere and only about 7,000,000 in the other. The portions of land in the water-hemisphere are the extremity of South America below THE EARTH'S CONTOUR AND SURFACE SUBDIVISIONS. IT 25 S., and Australia, together with the islands of the East Indies, the Pacific, a.nd the Antarctic. London and Paris are situated very near the center of the land-hemisphere. General arrangement of the oceans and continents. Oceans and conti- nents are the grander divisions of the earth's surface. But, while the continents are separate areas, the oceans occupy one continuous basin or channel. The waters surround the Antarctic pole and stretch north in three prolongations, the Atlantic, the Pacific, and the Indian oceans. The land is gathered about the Arctic, and reaches south in two great continental masses, the occidental and oriental, called America and Eurasia; but the latter, through Africa and Australia, has two southern prolongations, making, in all, three, corresponding to the three oceans. Thus the conti- nents and oceans interlock, the former narrowing southward, the latter northward. This subject is illustrated on the map, page 47. It is a Mercator's chart of the World, which, while it exaggerates the polar regions, has the great advantage of giving correctly all courses, that is, the bearings of places and coasts. The trends of lines (" trend " means merely course or bearing) admit, therefore, of direct comparison upon such a chart. It is important that the globe should be carefully studied in connection with it, in order to correct misapprehensions as to distances in the higher latitudes, and to appreciate the convergences between lines that have the same compass-course. The low lands of the continents on this chart, or those below 800 feet in elevation above the sea, are distin- guished from the higher lands and plateaus by a lighter shading. The oceans are crossed by isothermal lines, which are explained beyond. The Atlantic is the narrow ocean, the mean breadth of the North Atlantic being about 2800 miles. The Pacific is the broad ocean, being 6000 miles across, or more than twice the breadth of the Atlantic. The Occident, or America, is the narrow continent, about 2200 miles in average breadth ; Eurasia, the broad continent, 6000 miles in average breadth. Each continent has, therefore, as regards size, its representative ocean. The Pacific Ocean, reckoning only to 62 S., has an area of 62,000,000 square miles. This is ten millions beyond the area of the continents and islands, and nearly one third of the earth's surface. (3) Oceanic depression. (a) Outline. The oceanic depression is a vast sunken area, varying in depth from 500 feet or less to probably 30,000 feet. The true outline of the depression is not necessarily the present coast- line. About the continents there is often a shallow region which is the submerged border of the continent. On the North American coast, off New Jersey, as shown on the bathymetric map (page 18), this submerged border extends out for 110 miles (and 120 from New York City), with a depth, at this distance, of only 600 feet, its slope outward only one foot in 968. At the 1.00-fathom line, as shown on the map, the waters suddenly deepen, and here the true oceanic basin begins. This continental border of the ocean (see large bathymetric map following page 20, on which the 100-fathom line is finely dotted) extends northward to Newfoundland and beyond, and DANA'S MANUAL, 2 18 PHYSIOGRAPHIC GEOLOGY. also southward to Cape Hatteras. Off the Carolinas it narrows much ; but in the Gulf of Mexico it has its usual width. At times in geological history it has been part of the actual dry border of the continent. This is proved by the existence of a river-channel, that of the Hudson, over its submerged surface, as shown on the accompanying map of the Atlantic border. As here seen, the depth. of water over this border is not 50 fathoms (300 feet) until within 15 miles of the 100-fathoin line. 74M Long Island Sound, jf| Long Island, and the Atlantic Border with Depths along Bathymetrio lines in fathoms ; lines in Long Island Sound 'the under-water Channel it Hudson River, from Coast Survey Charts. 72:00 SCALE OF'Mll-ES J> 10 20 30 40 ^0 60 70 400 Map of the Atlantic border. On the Pacific side of both North and South America the submerged continental border is narrow. Off California, the distance to the 100-fathom line is in general only about 10 miles. There is then a sharp descent to 500 or 600 fathoms, and from this a decline of 1600 to 2400 fathoms within 40 or 50 miles. This is in great contrast with the Atlantic border. G. Davidson, of the Coast Survey, reports the existence of several deep submarine channels leading outward from the coast, which are most proba- bly due to streams that flowed along them at some time when the land stood much above its present level. THE EARTH'S CONTOUR AND SURFACE SUBDIVISIONS. 19 Great Britain stands on a broad continental border not over 600 feet deep, and is therefore part of the European continent. A large part of the German Ocean is not over 95 feet deep. In a similar manner, the East India Islands down to a line by the north of New Guinea and Celebes are a part of Asia, the depth of the seas between seldom exceeding 300 feet, while New Guinea is a part of Australia. In like manner, the Falkland Islands are a part of South America. These facts with respect to the 100-fathom .(600 feet) limit off the American and other coasts are illustrated on the following map. (6) Depths of the ocean. The depths of the ocean are given on the following bathymetric map, prepared by the author from the charts of the United States and British Hydrographic Department, and from the soundings of the vessels of the United States Fish Commission. The lines marking equal depths are made heaviest for the greatest depths, as explained on the map. The depths are given in 100 fathoms, 21 meaning 2100 fathoms (12,600 feet). The mean depth of the whole ocean has been estimated at 14,000 feet ; that of the North Atlantic, at 15,000 ; and that of the North Pacific, at 16,000 feet. As exhibited on the map, the western half of the Pacific and Atlantic oceans has greater mean depth than the eastern; for it contains all the 4000-fathom areas, and the larger part of the 3000-fathom areas. In the Indian Ocean the eastern side is the deeper. In the North Atlantic, deep waters and abrupt slopes extend along near the north shores of the West India Islands ; and in this line, north of Puerto Eico, occurs the greatest depth of the Atlantic Ocean, 4561 fathoms, or 27,366 feet. The mean slope from the Puerto Eico coast to the bottom is about 1 : 14. A deep trough with abrupt sides extends from this depression westward, north of Haiti or San Domingo ; and south of Cuba there are depths between 18,000 and 21,000 feet. In the Pacific, off the east shore of northern Japan and the Kurile Islands, there is a long 4000-fathoui area, in which the greatest depth found is 4656 fathoms, or 27,936 feet. An isolated depression of 4475 exists south of the largest end of the Ladrone Islands, and others over 4000 fathoms southeast of the Friendly Islands. In the North Atlantic, between Greenland and Iceland and Norway, the great Scandinavian plateau lies at a depth, in general, of only 1500 to 3000 feet; and along one course the greatest depth does not exceed 3600 feet. Iceland stands upon it and is prolonged in a ridge under water southwest- ward for 750 miles, and northeastward to the island of Jan Mayen. The plateau has to the north of it a large, deep region of 12,000 to 15,000 feet. To the southward it is prolonged southwestward in a relatively shallow area, called the Dolphin shoal, which passes near the middle of the ocean to the parallel of 25 N. or beyond, with less than 12,000 feet of water over it, and mostly under 9600 feet. Either side, the depths are 15,000 feet or over, and 20 PHYSIOGRAPHIC GEOLOGY. to the westward, to a large extent, 17,400 to 21,000 feet. The facts show plainly that if this Dolphin shoal was ever emerged as an Atlantic conti- nent, the fabled Atlantis of speculation, it never could have contributed any of its detritus to the American continent. It belongs more to the European side. Another shallow area occupies the middle of the south Atlantic basin in a nOrth-and- south direction and at its north end it is prolonged west-northwestward toward shallow areas farther west. Whether the shallow area about its southern extremity reaches into antarctic seas is not yet ascertained. A large shallow area exists on both sides of Pata- gonia, with a west-northwest trend (see map). It may be continued in the Pacific to the Paumotus and beyond ; if so, it follows the course nearly of the axis of the Pacific Ocean, as the Dolphin shoal does that of the North Atlantic. The West India sea has three deep areas : that of the Caribbean Sea, 17,000 feet in greatest depth (which has its deepest connection with the Atlantic between Santa Cruz and Puerto Rico, 5400 feet) ; the Cuban sea, or west Caribbean, separated from the east Caribbean by shallow waters 600 to 4080 feet (100 to 680 fathoms) between Honduras and Jamaica, with a maximum depth of more than 20,000 feet ; and the Gulf of Mexico, 12,714 feet in maximum depth. The Mediterranean Sea, 2100 miles long, has likewise its three deep-water areas: the eastern or "Levant" sea, about 13,000 feet in greatest depth ; the central, between Sardinia and Italy (separated from the eastern by relatively shallow water, not ever 200 fathoms, between western Sicily and Tunis, in Africa), 12,500 feet ; and the western, 9500 feet. The Straits of Gibraltar are mostly about 900 fathoms deep, but only 160 between Cape Spartel and Cape Trafalgar. The ranges of islands show the chief courses of shallow water in the ocean, and the bathymetric lines drawn about them, the outline of the basement ridges, of which the islands are the summits. Some of the isolated islands, especially those of coral-reef origin, have great depths close about them. Bermuda, in the Atlantic, has a depth of nearly 16,000 feet (2650 fathoms) within 25 miles to the eastward, whence the mean submarine slope is 1:8^; and a depth of 12,000 feet exists within six miles on one side and 9J miles on the opposite making the mean submarine slopes to this depth very steep, they being i : 2'64 and 1 : 4-2. The small Phoenix Islands, in the central Pacific, stand in a large area of 18,000 to 21,000 feet, and have depths of 18,000 to 20,000 feet between them, with similarly steep submarine slopes ; in one case a slope to the 12,000 point of 1 : 1*5. At Keeling atoll, in the Paumotu Archipelago, Captain Fitzroy, R. N., found no bottom in 7200 feet at 2200 yards from the breakers which gives a pitch-off exceeding 1 : 0-92. The island chains of the ocean may seem to indicate that great irregu- larity prevails elsewhere over the bottom of the ocean. But, while abrupt depressions and elevations do exist, the abyssal slopes are in general very gradual. One remarkable exception is the occurrence in the vicinity of the Canaries of a submarine crater a few miles wide and 1000 feet deep. Such cases are most likely to occur in the vicinity of volcanic islands. Whether the great depths south of the Ladrones and the Friendly Islands are craters or not is undetermined. A U S Rvl N.S.WAUSV BATHYMETKIC PACIFIC AND ATLANTIC OCEANS. THE EARTH'S CONTOUR AND SURFACE SUBDIVISIONS. 21 To appreciate the oceanic basins, we must conceive of the earth without water, the depressed areas, thousands of miles across, sunk 10,000 to perhaps 30,000 feet below the bordering continental regions, and covering four elevenths of the whole surface. The continents, in such a condition, would stand as elevated mountain plateaus encircled by one great uneven, almost featureless, basin. If the earth had been left thus, with but shallow briny lakes about the bottom, there would have been an ascent of five miles or more from the Atlantic basin to the lower part of the continen- tal plateau, and about five miles more to scale the summits of the loftier mountains of the globe. The continents would have been wholly in the regions of the upper cold, all alpine, and the bottoms of the oceanic basin under oppressive heat, with drought and barrenness universal. The uneven surface of the oceanic basin has been leveled off to a plain by filling it with water. The greatest heights of the world have thereby been diminished more than one half, and genial climates substituted for intol- erable extremes, rendering nearly all the emerged land habitable, and giving moisture for clouds, rivers, and living species. By the same means distant countries have been bound together by a common highway, into one arena of history. The calculated mass of the ocean, taking the depth as above given, is 1,320,000,000,000,000,000 tons. (4) General view of the land. (a) Position of the land.. The land. of the globe has been stated to lie with its mass to the north, about the Arctic pole, and to narrow as it extends southward into the waters of the southern hemisphere ; with the mean southern limit of the continental lands in the parallel of 45, or just half-way from the equator to the south pole. South America reaches to 56 S. (Cape Horn being in 55 58'), which is the latitude of Edinburgh or northern Labrador; Africa only to 34 51' (Cape of Good Hope), nearly the latitude of the southern boundary of Tennessee, and 60 miles nearer the equator than Gibraltar ; Tasmania (Van Diemen's Land) to 43^- S., nearly the latitude of Boston or northern Portugal. (b) Distribution. The independent continental areas are three in num- ber : America, one ; Europe, Asia, or Eurasia, and Africa, a second ; Australia, the third. Through the East India Islands, Australia is approximately con- nected with Asia, nearly as South America with North America through the West Indies ; and, regarding it as thus united, the great masses of land will be but two, the American, or Occidental, and Europe, Asia, Africa, and Australia, or the Oriental. But, further, these great masses of land are divided across from east to west by seas or archipelagoes. The West Indies (between the parallels of 10 N. and 30 K), the Mediterranean (between 30 K and 45 N.), and the Bed Sea, and the East Indies (between 30 N. and 10 S.), with the connect- ing oceans, make a nearly complete band of water around the globe, sub- 22 PHYSIOGRAPHIC GEOLOGY. dividing the Occident and Orient into north and south divisions. Cutting across 37 miles at the Isthmus of Darien, where at the lowest pass the greatest height above mean tide level does not exceed 260 feet, as has been done at the Isthmus of Suez, where the highest point of the isthmus is only 40 feet above the sea, the girth of water would be unbroken. This belt of water, like the continents, is situated mostly in the northern hemisphere, instead of corresponding in its course to any great circle. America is thus divided into North and South America. The oriental lands have one great area on the north, comprising Europe and Asia com- bined, often named Eurasia, and, on the south, (1) Africa, separated from Europe by the Mediterranean, and (2) Australia, separated from Asia by the East India seas. Thus the narrow Occident has one southern prolongation, and the wide Orient two. The Orient is thus equivalent to two Occidents in which the northern areas coalesce, Europe and Africa one, Asia and Australia the other ; so that there are really three doublets in the system of continental lands. The Caspian and Aral, which are salt seas, lie in a depression of the continent of great extent, the Aral being near the level of the ocean, and the Caspian 84 feet below that of the Black Sea. The continents have several Common features entitling them to be viewed as individuals under a common type of structure. They have (1) a like position on the sphere, each lying with its head or broader end to the north, and the tapering extremity to the south. North America, South America, and Africa strongly exhibit this characteristic ; Asia somewhat less mani- festly, yet decidedly in the great triangles of her southern border, Hindostan and Siam. Australia is seemingly an exception ; but there is evidence that this land has been narrowed and shortened by subsidence, and thus has lost New Zealand, its eastern front, and probably a large region to the south. (See large bathymetric map following page 20.) Another striking fact, showing system in arrangement, is seen (2) in the relative positions of the southern and northern continents. South America and Australia are not to the south of the related northern continent ; on the contrary, the center of South America is about 40 in longitude east of that of North America, or nearly an eighth of the sphere, and Australia 40 east of that of Asia. Thus there is a zigzag alternation in the positions of the four great masses of land. Further, (3) the curving line of islands in the West Indies from Florida to Trinidad is similar in form to that between Malacca through Sumatra and New Guinea to New Zealand, although much shorter. These are three of the points in which the continental individualities exhibit the system that exists in the earth's physiognomy. (c) The islands. The islands adjoining the continents are properly conti- nental islands. Besides the examples mentioned on page 19, Japan and the ranges of islands of eastern Asia are strictly a part of Asia, for they con- form in direction to the Asiatic system of heights, and are united to the THE EARTH'S CONTOUK AND SURFACE SUBDIVISIONS. 23 main by shallow waters. Vancouver Island and others north of it are similarly a part of North America ; Chiloe, and the islands south to Cape Horn, a part of South America; and so in other cases. In general they correspond to a broader mountain range more or less submerged. The oceanic islands are, in general, as has been stated, the summits of submerged oceanic mountain chains. The Atlantic arid Indian oceans are mostly free from them. The Pacific contains about 675 islands, with a mean area of only 80,000 square miles. Excluding New Caledonia and some other large islands in its southeastern part, the remaining 600 islands have an area of but 40,000 square miles, or less than that of the state of New York. (d) Mean elevation of the land. The mean height of the continents above the sea has been estimated at nearly 1800 feet, and the mean height of them severally is stated as follows : Europe, 975 feet ; Asia, 2880 ; North America, 2000 ; South America, 1750 ; and Africa, probably about 2000 feet. The material of the Pyrenees spread over Europe would raise the surface only 6 feet ; and the Alps, though of four times larger area, only 22 feet. The following estimates have been made for the mean heights of the United States : for the whole area, Alaska excluded, 2500 feet ; Alabama, 500 ; Arizona, 4100 ; Arkansas, 650 ; California, 2900 ; Colorado, 6800 ; Connecticut, 500 ; Delaware, 60 ; District of Co- lumbia, 150 ; Florida, 100 ; Georgia, 600 ; Idaho, 5000 ; Illinois, 600 ; Indiana, 700 ; Iowa, 1100 ; Kansas, 2000 ; Kentucky, 750 ; Louisiana, 100 ; Maine, 600 ; Maryland, 350 ; Mas- sachusetts, 500 ; Michigan, 900 ; Minnesota, 1200 ; Mississippi, 300 ; Missouri, 800 ; Mon- tana, 3400 ; Nebraska, 2600 ; Nevada, 5500 ; New Hampshire, 1000 ; New Jersey, 250 ; New Mexico, 5700 ; New York, 900 ; North Carolina, 700 ; North Dakota, 1900 ; Ohio, 850 ; Oklahoma, 1300 ; Oregon, 3300 ; Pennsylvania, 1100 ; Rhode Island, 200 ; South Carolina, 350 ; South Dakota, 2200 ; Tennessee, 900 ; Texas, 1700 ; Utah, 6100 ; Vermont, 1000 ; Virginia, 950; Washington, 1700; West Virginia, 1500; Wisconsin, 1050; Wyoming, 6700. (Gannett.) The extremes of level in the land, so far as now known, are, 1390 feet below the level of the ocean at the Dead Sea, 1300 feet in the deepest part of the Jordan valley, and 29,002 feet high in Mount Everest of the Himalayas, which have many peaks over 25,000 feet. In America, Death Valley, on the southeast border of California, descends 480 feet below the sea level. As stated by F. S. Coville, it is 175 miles long and 20 in greatest width, and has the Funeral Mountains, 7000 feet high, on the east, and the Panamints, 11,000 feet, on the west. (5) Subdivisions of the surface, and character of its reliefs. The surfaces of continents are conveniently divided into (1) lowlands ; (2) plateaus, or elevated table-lands ; (3) mountains. The varying levels above the sea make up the reliefs of a continent. The limits between these subdivisions are quite indefinite, and are to be determined from a general survey of a country rather than from any specific definitions. LOWLANDS. The lowlands include the extended plains or country lying not far above tide level. In general they are less than 1000 feet above the sea; but they are marked off rather by their contrast with higher lands of 24 PHYSIOGRAPHIC GEOLOGY. the mountain regions than by any special altitude. The surface is usually undulating, and often hilly. The great interior region of the North Ameri- can continent, including the Mississippi valley, is an example of an interior plain ; also the plains of the Amazon ; the pampas of La Plata ; the lower lands of Europe and Asia. Frequently the surface rises gradually into the bordering mountain-declivities, as in the case of the Mississippi plains and the Eocky Mountain slope. Broad,' low plains between mountain ranges and the seashore are called coastal plains. Along the eastern border of North America from New Jersey southward, the coastal plains are broad and have navigable streams. Next west is a region of more uneven and rocky country with rapid streams the Piedmont region, which extends to the Appalachian region, or that of the mountains. A mountain is either a single peak, as Mount Etna, Mount Washington, Mount Blanc ; or a ridge ; or a series of ridges, sometimes grouped in many, more or less parallel, lines. A mountain range consists of a series of ridges closely related in position, direction, and origin: as in the Appalachian ranges, the Wasatch, the Sierra Nevada. A sierra is, in Spanish, the name of a ridge, or group of ridges, of serrated or irregular outline. A mountain system consists of two or more mountain ranges, of the same period of origin, belonging to a common region of elevation, and generally either parallel or in consecutive lines, or consecutive curves, with often inferior transverse lines of heights. A mountain chain consists of two or more mountain-systems of different periods of origin, in the same part of a continent. The oldest of the mountain ranges in a chain is called the protaxis so named from the Greek for first and axis (see the map of the Archaean areas on page 443). The other ranges are usually parallel to the protaxis, and may, or may not, have greater height. The Appalachian Chain ex- tends from Canada to Alabama, and comprises (1) the protaxis, represented by the Highlands of New Jersey and Putnam County, New York, and their continuation northward interruptedly along the eastern half of the Green Mountains into Canada, and southward, as a narrow, interrupted area, through Pennsylvania, and a very broad area through Virginia, to Georgia ; (2) the Taconic Eange, along the borders of New England and New York to New Jersey and beyond ; and (3) the Appalachian Eange. The Eocky Mountains also have a protaxis, with approximately paral- lel ranges of later formation. This protaxis is the " Front Eange " in Colo- rado, nearly 1000 miles from the Pacific coast, making the Pacific border region in this part very wide. But to the north, in Montana and Wyoming, the protaxis makes a westward bend of 250 miles, and then resumes a north- westward course and continues to the parallel of 52-J- , and is represented beyond this in isolated ridges ; consequently the Pacific border region of British America is relatively narrow. The line to the north of the United States appears to be represented to the south in the Archaean axis of the Wasatch and some other similar ridges. The very large area of the Pacific THE EARTH'S CONTOUR AND SURFACE SUBDIVISIONS. 25 border, lying between the Wasatch line and the line of the Front Eange, is distinctively a Rocky Summit area, and peculiar to the United States portion of the chain. A cordillera is a combination of mountain chains. The Coast Cordillera within about 150 miles of the coast includes the Sierra Nevada and Cascade ranges and a range in continuation in British Columbia, which constitute together a Sierra Chain, and have heights equal to those of the Rocky Mountain summit, and a Coast Chain 2000 to 4000 feet high in California, which is continued in the Vancouver Eange of British America, 484 feet high in one Vancouver peak, and, beyond the islands of the coast, in the lofty Fairweather and St. Elias line of heights. On the terms range, system, chain, cordillera, etc., see further, page 389. PLATEAUS. A plateau is an extensive elevated region of flat or hilly surface, sometimes intersected by ranges of mountains. Any extensive range of generally flat country that is over a thousand feet in altitude is called a plateau. It may lie along the course of a mountain chain, or occupy a wide region between distant chains. The high land that forms the southern half of New York is generally 1500 to 2000 feet high, and reaching an elevation of more than 4000 feet in the Catskills, is the northern part of a plateau which southward extends through Pennsylvania to Tennessee, and in the latter re- gion constitutes the Cumberland Table-land. It is an example of a marginal plateau, connected in origin with a mountain range, that of the Appalachian Mountains, and constituting its outer margin. The channeling action of running water has mostly obliterated the plateau character, and converted the region into a group of peaks, ridges, and valleys. In this way high plateaus have often been sculptured into mountain-like forms. The " high plateaus " of southern Utah, which range in height from 7000 to 9500 feet, are properly a marginal appendage to the Wasatch Eange, as their elevation was connected with that attending the making of these mountains. Other plateaus are intermont plateaus. They occupy the interval between mountain ranges, chains, or cordilleras, and are the highest and largest of plateaus. Between the Eocky and Sierra cordilleras a broad plateau extends from Mexico northwestward through British America. It is mostly from 3000 to 5000 feet in altitude, but the Columbia Eiver and the Colorado have each cut a way through the Sierra Chain and reduced the level by denudation. There are many high ridges in the plateau, parallel in course, or nearly so, to the mountain ranges of the sides, and in part of Oregon and of British Columbia ridges occupy the whole breadth ; but in general the plateau features are well defined. The portion of the plateau between the Colorado and Columbia rivers is called the Great Basin. It has the Great Salt Lake and the Wasatch Mountains on the east, and the Sierra Nevada and Cascade Mountains on the west, and in this part it is nearly 500 miles wide. Its surface is mostly 4000 to 5000 feet above tide level ; but although so high, it has no outside drainage. Its streams are short, and dry up over arid saline plains or end in saline lakes. Great Salt Lake, in Utah, is one of these lakes near its eastern 26 PHYSIOGRAPHIC GEOLOGY. border, and Mono Lake in California, at the foot of the lofty Sierra, is another on the western border. The eastern half of the plateau south of the Colorado River extends south into Mexico, and there has similar arid features, with saline lakes and inside drainage. The plateau of Tibet is an intermont plateau between the main range of the Himalayas and the Kuen-Lun Mountains. It is about 13,000 feet in altitude, but is overlooked by mountains having an altitude of 25,000 to 29,000 feet, and has its own ridge of 20,000 feet. It is 1200 miles from east to west, and half this in mean breadth ; but its eastern half is much encum- bered by ridges. The plateau of Quito, about 300 miles long, 40 miles wide, and 10,000 feet above tide level, is situated between two parallel Cordilleras of the Andes, the eastern of which contains among its snow-capped cones or domes, Cayambe (19,535, and on the equator), Antisana, Cotopaxi (19,613), Sangay ; and the western, including Chimborazo (20,498 feet), Pichincha (15,924 feet), and others. The plateau of Bolivia has an elevation of 12,900 feet, with Lake Titicaca at 12,830 feet, and the city of Potosi at 13,330 feet. In Europe, Spain is for the most part a plateau about 2250 feet in average elevation; Auvergne, in France, another, of about 1100 feet ; Bavaria, another, of 1660 feet. Persia is a plateau varying in elevation between 2000 and 4000 feet, with high ridges in many parts. The Abyssinian plateau, in Africa, has an average elevation of more than 7000 feet ; the region of Sahara about 1500 feet, except the southern part, which lies mostly at a greater altitude than 650 feet ; that of southern Africa south of the parallel of 10 S. from 3000 to 4000 feet in mean altitude, and rising into many high summits, with the ele- vation least to the west. MOUNTAINS. (a) Slopes of mountains. The mountain mass. The slopes of the larger mountains and mountain chains are generally very gradual. Some of the largest volcanoes of the globe, as Etna (Sicily) and Loa (Hawaii) 3 have a slope of only six to eight degrees: such mountains are broad cones, having a base of 40 miles or more. The higher volcanic cones of western America are mostly 25 to 35 in angle of slope. The average eastern slope of the Eocky Mountains seldom exceeds 10 feet a mile, which is about one foot in 500, equal to an angle of only 7'. On the west the average slope is but little less gradual. The rise on the east continues for 600 miles, and the fall on the other side for 400 to 500 miles ; the passes at the summit have a height of 4944 to 10,000 feet ; and above them, as well as over different parts of the slopes (especially on the west), there are ridges carrying the altitude above 14,000 feet. The highest part of the range is in Colorado, where the passes are 11,000 to 13,000 feet high ; while in latitude 32 the passes are about 5200 feet ; on the Central Pacific Eailroad, 6184 feet high ; in Canada, 5264 to 7100 feet high ; and on the Canadian Pacific (the Kicking Horse Pass) 5300 feet high. The moun- tain mass, therefore, is not a narrow barrier between the east and west, as might be inferred from the ordinary maps, but a vast yet gentle swell of the surface, having a base 1000 miles in breadth, and the slopes diversified with various mountain ridges, or spreading out in plateaus at different levels. THE EARTH S CONTOUR AND SURFACE SUBDIVISIONS. 27 In the Sierra Nevada, the western (or gentler) slope is between 100 and 250 feet to the mile, and the eastern, for a larger part of its length, 1000 feet. In the Andes the eastern slope is about 60 feet in a mile, and the western 100 to 150 feet; the passes are at heights from 12,500 to 16,160 feet, and the highest peak Sorata in Bolivia 25,290 feet. The slope is much more rapid than in the Kocky Mountains. But there is the same kind of mountain mass variously diversified with ridges and plateaus. The exist- ence of the great mountain mass and its plateaus is directly connected with the existence of the main ridges. But it will be shown in another place that the ridges may have existed long before the mass had its present elevation above the sea. In the Appalachians the mountain mass is very much smaller, and the component ridges are relatively more distinct and numerous ; and still the general features are on the same principle. The greatest height Mount Mitchell or Black Dome in North Carolina is 6707 feet. It is common to err in estimating the angle of a slope. To the eyes of most travelers, a slope of 60 appears to be as steep as 80, and one of 30 to be at least 50. In a front view of a declivity it is not possible to judge rightly. A profile view should always be obtained and carefully observed before regis- tering an opinion. In Fig. 3 the bluff front facing the left would be ordinarily called a vertical precipice, while its angle ^>f slope is actually about 65 ; and the talus of broken stones at its base would seein at first sight to be 60, when really 40. 4. 6. Fig. 4 represents a section of a volcanic mountain 3 in angle ; Fig. 5, another, of 7, the average slope and form of Mount Kea, Hawaii ; Fig. 6, the same slope with the top 7. 8. rounded, as in Mount Loa ; Fig. 7, a slope of 15 ; Fig. 8, Jorullo, in Mexico, which has one side 27 and the other 34, as measured by N. S. Manross ; Fig. 9, a slope of 40, 28 PHYSIOGRAPHIC GEOLOGY. the steepest of volcanic cones. The lofty volcanoes of the Andes are not steeper than in Fig. 8, although often represented with angles of 40 to 50. With a clinometer (see Fig. 89, page 100) held between the eye and the mountain, the angle of slope may be approximately measured. When no instrument is at hand, it is easy to estimate with the eye the number of times a vertical, as AB in Fig. 5, is contained in the semi-base, BC ; and, this being ascertained, the angle of slope may be easily calculated. The ratio 1 : 1 corresponds to the angle 45 ; 1 : 2 to 26 34' ; 1 : 3 to 18 26' ; 1 : 4 to 14 2' ; 1 : 5 to 11 18|' ; 1 : 6 to 9 28' ; 1 : 7 to 8 8' ; 1 : 8 to 7 7'' ; 1 : 9 to 6 20' ; 1 : 10 to 5 421' j 1 : 12 to 4 46' ; 1 : 15 to 3 49' ; 1 : 20 to 2 52'. The inclinations corresponding to these ratios may be easily put into a diagram. For altitudes over the United States, see Bulletin No. 76, U. S. Geol. Survey, by H. Gannett, 1891. (b) Ridges. The ridges of a chain vary along its course. After con- tinuing for a distance, they may gradually become lower and disappear ; and while one is disappearing, another may rise to the right or left ; or the mountain, for scores of leagues, may be only a plateau without a high ridge, and then new ranges of elevations may appear. The Rocky Mountains well exemplify this common characteristic, as may be seen on any of the recent maps. The Sierra Nevada dies out where the Cascade Range begins ; and each has minor examples of the same principle. The Andes are like the Rocky Mountains ; only the parts are pressed into narrower compass, and the crest ranges are hence continuous for longer distances. The Appalachian ridges rise and sink along the course of the chain. 10-15. 14 15 The general idea of this composite structure is shown in Figs. 10 to 15, where each series of lines represents a series of ridges in a composite range. In Fig. 10 the series is simple and straight ; in Fig. 11 it is still straight, but complex ; in Fig. 12 the parallel parts are so arranged as still to make a nearly straight composite range; while in Figs. 13 and 14 the succession forms a curve ; and in Fig. 15 there are transverse ridges in a complex series. In ridges or ranges thus compounded, the component parts may lie distinct, or they may coalesce so as not to be apparent. RIVEK SYSTEMS. Plateaus and mountains are the sources of rivers. They pour the waters along many channels into the basin or low country toward which they slope ; and the channels, as they continue on, unite into larger channels and trunks which bear the waters to the sea. The basin and its surrounding slopes make up a river system or drainage area. The THE EARTH'S CONTOUR AND SURFACE SUBDIVISIONS. 29 extent of such a region will vary with the position of the mountains and ocean. Over a continent there are the interior and the border river systems or drainage areas ; the former very large and few, the latter many and relatively small. In North America, having the Rocky Mountains on the west and the Appalachian on the east, the great interior slopes are three : southward, along the Mississippi; eastward, along the St. Lawrence; and northward, along the Mackenzie and other streams. The tributary streams of the Mississippi rise on the west, among the heights of the Kocky Mountains, the region in and near the Yellowstone Park supplying waters to the Missouri through a number of tributaries including the Yellowstone and the Front Range of Wyoming, Colorado, and New Mexico, giving origin to the Platte, Arkansas, and Canadian rivers; on the north, in the central plateau of the continent, in northern Minnesota, west of Lake Superior, near lat. 47-48, long. 93-96, 1680 feet in elevation a region of lakes which is the source of the Mississippi of the maps ; and on the east, in the Appalachians, from western New York to Alabama. There are also other rivers flowing from the west into the Gulf of Mexico ; but, in a comprehensive view of the continent, these belong to the same great river system. The St. Lawrence commences in the head waters of Lake Superior, about the same central plateau, embraces the Great Lakes with their tributaries, and flows finally northeastward, following a northeast slope of the continent. North of Lake Superior and the head waters of the Mississippi, as far as the parallel of 55, there are other streams, which also flow northeastward, deriving some waters from the Rocky Mountains through the Saskatchewan, and reaching the ocean through Hudson Bay. Winnipeg Lake is here in- cluded. These belong with the St. Lawrence, the whole together constituting a second continental river system. The Mackenzie is the central trunk of the northern river system. Start- ing from near the parallel of 55, it takes in the slopes of the Rocky Mountains adjoining, and much of the northern portion of the continent. Athabasca, Great Slave, and Great Bear lakes lie in this district. The border river systems depend for their extent 011 the height and slope of the mountains, the distance from the coast, and the structure of the mountain region. The Appalachian range, mostly below 5000 feet in height, is 150 to 300 miles from the coast. But the mountains are a succession of overlapping parallel ridges, and the rivers in their higher parts go back and forth between the ridges, thus deriving a more gradual slope, a much greater length, and producing a longer range of watered country. The Rocky Moun- tains, 10,000 to over 14,000 feet high, are 600 to 1000 miles from the coast. But a second chain of equal height that of the Sierra and Cascade ranges, with the range of the California peninsula, which is probably a southern continuation of the line stands as a barrier to the more eastern drainage 30 PHYSIOGRAPHIC GEOLOGY. within 150 miles of the coast, and thus influences the extent of the Pacific border river systems. The western drainage of the Kocky Mountains, rising partly in the Yellowstone Park, and partly just south of it, has its outlet to the ocean through the Colorado and Gulf of California, and along the Columbia River and streams farther north, the Colorado and Columbia reaching salt water at points 1200 miles apart. Thus it is that the " Great Basin " is without drainage. Again, a subordinate range of this chain, that of the Coast Kange, 2000 to 4000 feet high, is a barrier, for 800 miles, to most of the drainage waters of the Sierra Nevada and Cascade Mountains ; and consequently the Sacramento and Joaquin rivers, and not the ocean, receive all the Sierra waters for 500 miles, and the Willamette, the waters of the Cascade Range for 150 miles. South America has an arrangement of interior river systems parallel to that of North America ; the Amazon flowing eastward, like the St. Lawrence ; the La Plata flowing southward, like the Mississippi ; the Orinoco and other streams northward, like the Mackenzie. This adds a fourth to the charac- teristics exhibiting parallelism in structure between two continents, North and South America (page 22). Africa, on the opposite side of the Atlantic, has the arrangement reversed as regards the east and west streams : the great Niger empties into the western ocean, the Atlantic ; the Nile is the northward-flowing stream ; but the southward-flowing interior waters are divided between the Congo draining to the southwestward and the Zambesi to the southeastward. The lengths and drainage areas of some of the largest of rivers are as follows : Amazon, length (L.) = 3545 miles, drainage-area (D.) = 2,264,000 square miles ; La Plata, L. = 2400, D. = 1,250,000 ; Mississippi, L. = 2800 (but from its mouth to the head of the Missouri 4200), D. = 1,285,000 ; Nile, L. = 3815, D. = 1,049,000 ; Congo, L. = 2900, D. = 1,540,000 ; Yenisei, L. = 2800, D. = 784,500 ; Amur, L. = 2380, D. = 583,000 ; Obi-Irtish, L. = 2320, D. = 725,000 ; Lena, L. = 2400, D. = 594,000 ; Yang-tse-Kiang, L. = 2800, D. = 548,000 ; Hoang Ho (Yellow River), L. = 2280, D. = 537,000. The lengths of the valleys, excluding the minor beds, are : the Amazon, 2600 miles ; the Mississippi, 1164 ; the Nile, 3100. II. SYSTEM IN THE RELIEFS OR SURFACE FORMS OF THE CONTINENTS. Law of the system. The mountains, plateaus, lowlands, and river regions are the elements, in the arrangement of which the system in the surface form of the continents is exhibited. The law at the basis of the system depends on a relation between the continents and their bordering oceans, and is as follows : First. The continents have in general elevated mountain borders and a low or basin-like interior. Second. The highest border faces the larger ocean. A survey of the continents in succession with reference to this law will exhibit both the unity of system among them and the peculiarities of each, dependent on their different relations to the ocean. SYSTEM IN THE SURFACE FORMS OF THE CONTINENTS. 31 (1) America. The two Americas are alike in lying between the Atlan- tic and the Pacific. North America, in accordance with the law, has on the Pacific side the side of the great ocean the Rocky Mountains, on the Atlantic side the low Appalachians, and between the two there is the great plain of the interior. This is seen in the annexed section (Fig. 16) from 16. west to east : on the west, the Kocky Mountains, with the double crest, at b ; the Sierra Range at a ; between a and b the Great Basin ; at d the Appa- lachians ; c the Mississippi ; and between d and b a section of the Mississippi river system. The Appalachians, on the east, reach an extreme height of but 6700 feet, and are in general under 2500 feet. To the north of North America lies the small Arctic Ocean, much encum- bered with land; and without any distinct mountain-chain facing the ocean. South America, like North America, has its great western range of moun- tains, and its smaller eastern range (Fig. 17); and the Brazilian line (6) is 17. closely parallel to that of the Appalachians. The Andes (a) face the very broad South Pacific, and have more than twice the average height of the Rocky Mountains ; moreover, they rise more abruptly from the ocean, with narrow shore plains. Unlike North America, South America has a broad ocean on the north, the North Atlantic in its longest diameter ; and along this northern coast a mountain chain extends through Venezuela and Guiana. (2) Europe and Asia. The land covered by Europe and Asia is a single area of land, only partially double in its nature (page 22). Unlike either of the Americas, it lies east-and-west, with an extensive ocean facing Asia on the south ; and its great feature lines are in a large degree east-and-west. The small Arctic Ocean is on the north ; the larger North Atlantic on the west ; the still larger North Pacific on the east : Africa and the broad Indian Ocean, singularly free from islands, are on the south. The boundary is a complex one, and the land between the Atlantic and Pacific is over 6000 miles broad. 32 PHYSIOGRAPHIC GEOLOGY. On the side of the North Atlantic there are the mountains of Scan- dinavia and the British Isles, the former having a mean height of 4000 feet and a maximum, in Galdhopig, of 8400 feet ; and farther south, the Alps and other mountains of eastern Europe, the higher portions covering but small areas. On the side of the larger Pacific there are loftier mountains in long ranges the Shan-a-lin range of Manchuria, having peaks of 10,000 to 12,000 feet, and the high Khingan range of 15,000 feet, facing China. Off the coast there is still another series of ranges, now partly submerged, viz. those of Japan and other linear groups of islands ; these stand in front of the interior chain, very much as the Cascade range and Sierra Nevada of the Pacific border of America are in advance of the summit ridges of the Eocky Mountains, and both are alike in being partly volcanic, with cones of great altitude. Thus viewing Eurasia across its whole breadth from west to east, there is an interior basin of immense extent, which includes some of the lowest land of the globe. The plains of eastern Europe, north of the Carpathians, com- prise three fifths of all Europe, and are situated, with reference to the mountain-border of Europe, like the Mississippi basin with reference to the Appalachians. Farther east there is the low land of the Caspian- Aral basin of western Asia, a million of square miles in area, over a fourth of it lying below the sea level. Facing the large and open Indian Ocean, and looking southward, stand the Himalayas, the loftiest of mountains, in which peaks of 20,000 feet and over are very numerous, and few passes are under 16,000 feet, called the Himalayas as far as Kashmir, and from there, where a new sweep in the curve begins, the Hindu-Kush, the whole over 2000 miles in length : not so long, it is true, as the Andes, but continued as far as the ocean in front continues. The Kuen-Lun Mountains, to the north of the Himalayas, make another crest to the great chain. Farther north lies the great interior arid plateau, the Desert of Gobi ; and then rise other mountain chains, the Thian-Shan to the northwest having peaks of 14,000 to 15,000 feet, the Yablonoi to the northeast, and farther north, the Altai facing Siberia. Beyond these stretches Siberia, an alluvial area, 1000 miles wide. 18. The diagram (Fig. 18) represents the general features of a section from north to south through the Himalayas. At a, there is the elevated land of India ; between a and 6, the low river-plain at the base of the Himalayas ; at b, the Himalayas ; b to c, Plains of Tibet ; c, the Kuen-Lun ridge ; c to d, Plains of Mongolia and Desert of Gobi ; at d, the Altai ; d to N, the Siberian plains. SYSTEM IX THE SURFACE FOKMS OF THE CONTINENTS. 33 The great desert-plateau of Gobi or Mongolia, 3000 to 4000 feet in eleva- tion, is a great interior basin, and the Altai and associated ranges are the mountains facing the Arctic seas. But the distance to those seas is so great that it is as reasonable to regard the Mongolian area as a plateau between high mountain ranges facing the Indian Ocean, and Arctic Asia, like Arctic America, as without any mountains bordering the small Arctic sea. The interior drainage system for Asia is without outlet. The waters are shut up within the great basin, the Caspian and Aral being the seas which receive the part of those waters not lost in the plains. The Volga and other streams, from a region of a million of square miles, flow into the Caspian. Lake Baikal, regarded as a Siberian lake, is 30 degrees of latitude, or over 2000 miles, from the Arctic coast. The Urals, 2000 to 3000 feet in mean altitude, stand as a partial barrier between Asia and Europe, parallel nearly with the mountains of Norway. Looking over the broad surface of North America and of Eurasia on the map, on page 47, the fact that the higher lands are on the side of the greater ocean is strikingly illustrated. In each, the dark shaded or more elevated portion is mainly on the Pacific side. (3) Africa. Africa has the Atlantic on the west, the broader Indian Ocean on the east, with Europe and the Mediterranean on the north, and the South Atlantic and Southern Ocean on the south. The northern half has the east-and-west position of Asia, and the southern the north-and-south of America ; and its reliefs correspond with this structure. The Guinea coast, belonging to the northern half, projects west in front of the south Atlantic, and is faced by the east-and-west Kong range, about 2000 feet high : and opposite, on the Mediterranean, there are the Atlas Mountains, the high plateau of which is about 3000 feet; one peak in the Atlas of Morocco is 13,000 feet high, although the ridges are generally 5000 to 7000 feet. The larger part of the Abyssinian Plateau is 6000 to 7000 feet in eleva- tion, but it has one summit of 15,000 feet. It extends into the great plateau of southern Africa; and just south of the equator stand Mount Kilima-Njaro, 18,715 feet high, and Mount Kenia, 18,000 feet, and near the meridian of 30, and 2 S., Euwenzori, 19,000 feet (Stanley). The pass from Zanzibar to Tanganyika is 5700 feet. A height of 6000 to 8000 feet continues south, becoming nearly 9000 feet in the South African Republic. The drainage of the interior is consequently westward, and the Zambesi is the only stream that breaks through and reaches the Indian Ocean. Africa has been well described as a shut-up continent, its coasts being mostly without bays. 19. The section Fig. 19 gives a general idea of its features from south to north (the heights necessarily much exaggerated in proportion to the DANA'S MANUAL 3 34 PHYSIOGRAPHIC GEOLOGY. length) ; a, the southern mountains ; b, the southern plateau ; c. Lake Tchad depression; d, Sahara plateau; e, oases depression; /, mountains on the Mediterranean, of which there are two or three parallel ranges. Africa has, therefore, a basin-like form, but is a double basin ; and its highest mountains are on the side of the largest ocean, the Indian. The height of the mountains adjoining the Mediterranean is the only exception to the relation to the oceans. (4) Australia. Australia conforms also to the continental model. The highest mountains are on the side of the Pacific, the larger of its border- oceans. Mountain ranges extend along the whole eastern border from Portland in Victoria to Cape York in the extreme north. The Australian Alps, in ISTew South Wales, facing the southeast shores, have peaks 5000 to 6500 feet in height. The Blue Mountains next to the north are 3000 to 4000 feet high, with some more elevated summits. On the side of the Indian Ocean the heights are 1500 to 2000 feet. The interior is an arid region, the center more than 600 feet above the sea. The continents thus exemplify the law laid down, and not merely as to high borders around a depressed interior, a principle stated by many geographers, but also as to the highest border being on the side of the greatest ocean. 1 This difference between the interior and the border regions runs parallel with another of geological nature : the border region in its older rocks, if not the newer, is a region usually of upturned beds, and the interior, for the most part, of nearly horizontal beds. The interior basin has this feature in North America, in South America, and over eastern Europe in the great plains of Turkey and Kussia. It is owing to this law that America and Europe literally stand facing one another, and pouring their waters and the treasures of the soil into a common channel, the Atlantic. America has her loftier mountains, not on the east, as a barrier to intercourse with Europe, but off in the remote west, on the broad Pacific, where they stand open to the moist easterly winds as well as those of the west, to gather rains and snows, and make rivers and alluvial plains for the continent ; and the waters of all the great streams, lakes, and seas make their way eastward to the narrow ocean that divides the civilized world. Europe has her slopes, rivers, and great seas opening into the same ocean ; and even central Asia has her most natural outlet westward to the Atlantic. Thus, under this simple law, the civilized world is brought within one great country, the center of which is the Atlantic, uniting the land by a convenient ferriage, and the sides the slopes of the Rocky Mountains and Andes on the west, and the remote mountains of Mongolia, India, and Abyssinia on the east. 2 This subject affords an answer to the inquiry, What is a continent as 1 First announced American Jour. Sci., II., vols. iii. 398, iv. 92, 1847, and xxii. 335, 1856. 2 See Guyot's Earth and Man. SYSTEM IN THE COURSES OF THE EARTH'S FEATURE LINES. 35 distinct from an island ? It is a body of land so large as to have the typical basin-like form, that is, independent mountain chains on either side of a low interior. The mountain borders of the continents vary from 500 to 1500 miles in breadth at the base. Hence a continent cannot be less than a thousand miles (twice five hundred) in width. 20. HI. SYSTEM IN THE COURSES OF THE EARTH'S FEATURE LINES. The system in the courses of the earth's outlines is exhibited alike over the oceans and continents, and all parts of the earth are thus drawn together into even a closer relation than appears in the principle already explained. The principles to which the facts point are as follows : (1) that two great systems of courses or trends prevail over the world, a northwestern and a northeastern, transverse to one another; (2) that the islands of the oceans, the outlines and reliefs of the continents, and the oceanic basins themselves, alike exemplify these systems ; (3) that the mean or average directions of the two systems of trends are northwest-by-west and northeast-by-north ; (4) that there are wide variations from these courses, but according to prin- ciple, and that these variations are often along curving lines ; (5) that, what- ever the variations, when the lines of the two systems meet, they meet nearly at right angles or transversely to one another. (1) Islands of the Pacific Ocean. The lines or ranges of islands over the ocean are as regular and as long as the mountain ranges of the land. To judge correctly of the seeming irregularities, it is necessary to consider that, in chains like the Rocky Mountains, or Andes, or Appalachians, the ridges vary their course many degrees as they continue on, sometimes sweeping around into some new direction, and then returning again more or less nearly to their former course, and that the peaks of a ridge are very far from being in an exact line even over a short course ; again, that several approximately paral- lel courses make up a chain. A. NORTHWESTERLY SYSTEM OF TRENDS. In the southwest- ern Pacific the New Hebrides (Fig. 20) show well this linear arrangement ; and even each island is elongated in the same direction with the group. This direction is nearly northwest (N. 40 W.), and the length 36 PHYSIOGRAPHIC GEOLOGY. of the chain is 500 miles. New Caledonia, more to the southwest, has approximately the same course, about northwest. Between New Hebrides and New Caledonia lies another parallel line, the Loyalty Group. The Solomon Islands, farther northwestward, are also a linear group. The chain is mostly a double one, consisting of two parallel ranges; and each island is linear, like the group, and with the same trend. The course is northwest-by-west, the length 600 miles. In the North Pacific, the Hawaiian range has a west-northwest course. The Sandwich or Hawaiian Islands (Fig. 21), from Hawaii to Kauai, make up the southeasterly part of the range, about 400 miles in length. Beyond this, the line extends to 175 E., making a total length of about 1500 miles, a distance as great as from New York to the Great Salt Lake in the Eocky Mountains, or from London to Alexandria. 22. H, Hawaii; M,Maui; 3, Kahoolawe ; 4, Lanai: 5, Molokai; O, Oahu; K, Kauai. So other faults might go on in- creasing the extent of the surface exposure. This is further illustrated in Fig. 129. Let A be a stratum 10,000 feet thick (a to c) and 100,000 feet long (a to b). Let it now be faulted, as in Fig. B, and the parts uplifted to a dip of 15, taking a common angle for the parts, for the sake of simplicity of illustration. The projecting portions being worn off by the ordinary processes of denudation, it is reduced to Fig. C, mn being the surface exposed to the observer. The first error that might be made from hasty observation would be that there were four distinct outcropping coal layers (call- ing the black layer thus), instead of one; and the second is the one above explained with regard to calculating the thickness of the whole stratum from the entire length mn in connection with the dip. Very often the beds have been shoved up over one another in the making of a monocline to such an extent that the faults are almost or wholly obliterated. A calculation of the thickness in such a case is impossible. If the stratum (Fig. 129 A) were in- clined 15 without faulting, it would stand as in D ; and if then worn off to a horizontal surface, the widest extent possible would be cr, which is less than half what it has with the three faults. A block of the size mentioned would require, in order to make it a monocline of 45, that one end should be dropped down 70,000 feet, or the other end raised as much, or that this amount of change should be divided between the two ends ; and for a mono- clinal block having a dip of 60, the drop-down or upthrust would have to be nearly 87,000 feet, or more than 16 miles. Calculating the thickness from the dip in a region is liable, therefore, to enormous error. 5. Conf or mobility, Unconf or viability. Successive strata in a region may be conformable to one another or uncon- formable. In the series of strata made over the earth's crust, the rocks of successive periods and ages have, in large parts of the world, been made B m TERRANES. 115 in regular succession, each stratum conformable in bedding to the preceding. This was true of the 40,000 feet of rock of the Appalachian region (referred to on page 353), out of which the Appalachian Mountains were finally made. This is an example of conformabUity, as the term is used in geology. Through the long series there is conformity in bedding. But these conformable strata rest on older rocks that have the bedding upturned and standing at various angles. Between the two there is uncon- formability in bedding. Fig. 130 illustrates this subject. The beds 2, 3, 4a, 46, are conformable to one another, but unconformable to the flexed rocks numbered 1. The 130. 1, Upturned Archaean rocks; 2, 3, 4a, 46, overlying strata, conformable with one another, but uuconformable with the Archaean. Logan. flexing of the rocks antedated the deposition of No. 2; and knowing the geological age of No. 2, some approximation is made toward a knowledge of the time of flexure. There may be three or four cases of unconf or m ability in the same region. For in each mountain-making epoch, new rocks are upturned, and the succeeding ones are laid down horizontal, as usual, over the upturned. Such unconformabilities belong especially to regions of moun- tain-making; for there occur the upturned rocks. Only a few miles away from the region of the mountain, the rocks that are unconformable in the latter may rest on one another in regular order, or conformably, as if no disturbance had anywhere taken place. The preceding figure has a fault-plane at /, and there is an unconformity between the beds on each side of it, but not unconformability. The uncon- formity introduced by faults is easily mistaken for true unconformability. Such unconformity is of frequent occurrence in all formations ; while uncon- formity in bedding indicates an epoch of mountain-making, a thing of rare occurrence in the geological history of a region. Besides this most important species of unconformability, that of the first kind, there are also two other kinds : (1) through changed sea-limit or overlap; (2) through surface erosion. Tlirough overlap. When, after the deposition of beds, a slight sinking of the region takes place, the next deposits there made may extend beyond the limits of the preceding, and overlap those outside. In such cases, although both deposits are approximately horizontal, there is still a degree of unconformability. Oscillations of the land surface, or of the water level, have gone on through the successive periods, so that unconformity by overlap is of very frequent occurrence, and of minor significance, though always of great geological interest. 116 STRUCTURAL GEOLOGY. Through an interim of erosion. Between the time of making two suc- cessive horizontal strata there is sometimes an interval of exposure to marine or fluvial erosion, which the worn upper surface of the lower stratum indicates. This, also, is unconformability in geology, and as the interim of erosion may be long, it is of importance. Yet in all periods, as in that of existing time, the deposits made during a period may be extensively worn away in some large regions before the period has closed ; partly worn away in many places it is sure to be. An uplift of 600 feet in the present era, putting a coral reef rock this much above the sea, is followed by cave- making and extensive removals. The amount of erosion is no certain evidence as to the length of time during its progress. Deposits are sometimes formed in basins or depressions of the surface. Such deposits may, in general, be distinguished by their thinning out toward the sides of the basin. Yet, when syn- clinal valleys are shallow, it is easy, and not uncommon, to mistake beds that are conformable with the strata below for such basin formations. The beds ab (Fig. 131) lie in the synclinal valley mn, like a basin deposit; but they were formed before the folding of the beds, and not after it. UNSTRATIFIED TERRANES. The unstratified terranes comprise (1) the great unstratified masses of granite and other related crystalline rocks ; (2) the various masses of ejected igneous rocks that lie in piles, not having the bedding due to successive flows, and not making part of any stratified series; (3) masses occupying fissures in the earth's crust or supercrust, and having thereby the nature either of dikes or veins. The facts connected with unstratified terranes are necessarily considered in Part III. on Dynamical Geology, and remarks here are therefore unnecessary. PAET III. DYNAMICAL GEOLOGY. DYNAMICAL GEOLOGY, as explained on page 14, treats of the causes of events in the earth's geological progress. These events include : I. Those concerned in the production and modification of the earth's rock structure, and in the development of its form and features. II. The changes in the earth's climates. III. The changes through geological time in the earth's vegetable and animal life. The explanations beyond relate mainly to the first of these classes of subjects. The succession in climates and in vege- table and animal life is considered only historically, under Historical Geology. The chief of the agencies directly concerned in geological work are the Atmosphere, the Waters, Heat, Chemical Force, and Life, each acting through or under general physical laws. The atmosphere and the waters, by means of which most rocks have been made, valleys excavated, mountains shaped, and a great amount of chemical work carried on, are the most prominent of the earth's exterior agencies. Life, in its geological work, is another of the exterior agencies. Heat has both an exterior and an interior source, with corresponding effects. As exhibited in igneous ejections and volcanoes it is an interior agent both in source of material and of force ; but the distribution of ejected material has taken place in part by means of the exterior agencies, water and air. The agencies that have made continents, oceanic depressions, and mountain ranges are largely interior in the origin of their forces and in their work. There are three chief sources of energy for these agencies : 1. THE EARTH'S ROTATION ON ITS AXIS, and ITS REVOLUTION AROUND THE SUN. (1) The rotation determining the earth's spheroidal shape, the length and alternations of its day, its zones of climate, and the system of movements in physical agencies ; (2) the revolution, causing, in case of col- lision with any foreign body (as a meteorite), a manifestation of force in the production of heat and in violent mechanical effects. 2. THE SUN : which, through its heat, light, and attraction, is the origin of movements in the air, oceans, and rivers; the origin of chemical ac- tivity and growth in the kingdoms of life, and of much chemical work in 117 118 DYNAMICAL GEOLOGY. inorganic nature; and the chief source of climatal conditions through all time since life began; which, further, in conjunction with the moon's attraction, is the origin of the energy-distributing tidal wave, and also, incidentally to the tidal movement, of tidal friction, with far-reaching, adverse, and fatal results in the retarding of the earth's rotation. 3. THE EARTH'S INTERIOR HEAT. Dynamical Geology is discussed beyond under the following heads : I. CHEMICAL WORK, as a means of superficial changes. II. LIFE, as a geological agent. III. THE ATMOSPHERE, as a mechanical agent. IV. WATER, as a mechanical agent : under the subordinate heads of Water in general ; Fresh waters ; Oceanic waters ; Glaciers and Icebergs. V. HEAT : under the heads of Sources of heat and their direct climatal effects ; Expansion and contraction ; Igneous action ; Metamor- phism ; Veins and ore-deposits. VI. HYPOGEIC WORK, or earth-shaping, mountain-making, and the attendant phenomena. I. CHEMICAL WORK. Chemical work is given the first place, because superficial chemical changes have been a prominent cause of the decomposition of rocks, and thereby one of the producers of the earth, clay, and other fragmental ma- terials which are worked into beds by the mechanically acting air and waters. It is also a source of superficial rock formations of different kinds. Chemical changes carried on at temperatures above the ordinary, as those of metamor- phism, are not here considered. The following is the order of subjects : 1, Solution ; 2, Oxidation and Deoxidation ; 3, Hydration, or the chemical absorption of water ; 4, Carbonic acid (C0 2 ) and humus acids as geological agents ; 5, Action of siliceous solu- tions ; 6, Chemical work of living organisms ; 7, Mechanical work of chemical products ; 8, Concretionary consolidation. Of this large subject only a brief review of the more prominent facts is possible in this place. SOLUTION. The water descending in rains takes from the atmosphere its elements (in the ratio of about two parts of nitrogen to one of oxygen) ; carbonic acid ; some sulphates and ammonium nitrates, especially about cities where there are coal fires ; and three or four parts in 10,000 of sodium chloride or common salt in the vicinity of the ocean ; besides atmospheric dust, enough of which is from organic sources to make the waters offensive after standing a few CHEMICAL WORK. 119 days. It gathers other materials as it flows, taking them from the soil and its organic decompositions, and from rocks or minerals, and especially where decompositions are in progress. It finds soda and potash in rocks containing feldspars ; lime and magnesia, in limestones and also more or less in many other rocks, fragmental and crystalline ; and various other materials in these and other rocks. Among the materials gathered up, the chief are calcium carbonate ; salts of iron ; magnesium, sodium and potassium carbonate, sul- phate or chloride; calcium chloride; humus acids from the soil; and carbonic acid from the soils and other sources ; besides, more sparingly, aluminum sulphates and lithium salts. Besides the gas carbonic acid, the waters often receive and discharge hydrogen sulphide and nitrogen, and sometimes the gases hydrogen and oxygen. The gatherings depend on the kinds of rocks washed by streams, both those of the surface and those of subterranean source. It was long since recognized that, through the gathering action of fresh waters, a lake without outlet might become saline, like the sea. The desert and semi-desert regions of the world often illustrate through the efflorescences that exist over the surfaces of old lake basins, as well as the salts in the waters of lakes, what solvent work the waters have done. The Great Basin in the west has been studied with reference to this subject by King, Gilbert, Eussell, and others. The moisture below comes up by capillary action ; and, as evaporation above is almost constant, owing to the excessive dry ness and heat (90 F. the mean over part of it for July), so also the production of the salts is in constant progress. The most abundant are common salt (NaCl), sodium carbonate and sulphate, with often calcium carbonate, and borates. From one of two samples of the saline deposits from the Lahontan region analyzed by Dr. T. M. Chatard were obtained, as cited by I. C. Russell, 72-69 per cent of sodium carbo- nate (Na 2 O.CO 2 ), 17-49 of sodium sulphate (Na 2 O.S0 3 ), 4-15 sodium borate (Na^O.B 4 6 ), 2-53 sodium chloride (NaCl), 1-18 potassium chloride (KC1), and 1-96 silica. In the other : 9-06 Na^O.COa, 27-05 Na 2 O.SO 3 , 1-00 Na 2 O.B 4 6 , 59-32 NaCl, 1-39 KC1, and 2-18 Si0 2 . In deposits of the dried-up Sevier Lake, south of the Great Salt Lake, Dr. O. Lcew obtained, as reported by G. K. Gilbert, (1) from those of the center of the lake: sodium sulphate 87-65, sodium carbonate 1-08, sodium chloride 2-34, with water 8-90 = 99-97 ; (2) from the middle or 3d layer of those of the margin, sodium sulphate 83-79, sodium chloride 13-84, magnesium sulphate 1-33, potassium sulphate 0-26, with water 0-78 = 100 ; from a layer overlying the last, (4th layer) sodium sulphate 2-71, sodium chloride 88-49, magnesium sulphate, potassium sulphate 0-11, water 3-40 = 100. The above are a few of the published analyses. These saline materials were once in solution in lakes of the region that are now dried up. Salt lakes are in some cases remnants of the ocean that once covered the land. But in the Great Basin, according to Gilbert, the saline ingredients have come from the soil and rocks of the region. Mineral springs, or sources of water holding mineral ingredients in solu- tion, are hence universally distributed. They include " pure " waters as well as the so-called "mineral waters." The latter contain some mineral salt generally in sufficient quantities to affect the taste ; and they are most 120 DYNAMICAL GEOLOGY. valued when sodium chloride is mostly absent, and when carbonic acid gas is present to give briskness to the waters. The ocean is the great mineral spring of the world ; and Artesian borings over the land very often show, by bringing salt water to the surface, that more or less sea water has generally been left along with the beds. About 3 per cent of sea water consists of soluble salts, and of these over f is common salt. When sea water along a flat shore becomes temporarily confined so that it can evaporate, the salts are deposited ; first gypsum or anhydrite, which goes down, according to Ursiglio, when the Beaume areometer stands at 16.75 ; and then the common salt when it is at 26.25. While this is depositing, the remaining solution, which is above, holds the magnesium sulphate and chloride, with the calcium chloride, and the iodide and borate, and is called the " mother liquor " or " bittern " ; and it is all nearly ready for deposition, the borate being among the latest although not the least solu- ble. Magnesium sulphate and magnesium-potassium chloride (carnallite) make much the larger part of the final depositions. But a new supply of salt water at this stage may prevent deposition from the bitter magnesium solution ; or the latter may be gradually drawn off to mix again with the sea water, or for deposition elsewhere. Common salt dissolves in about three parts of either hot or cold water ; magnesium sulphate, in about four parts at 32 F.,. but in one third as much water at 212 F. Sodium sulphate is most soluble in warm water ; hence the waters of the Great Salt Lake deposit it if cooled down to 20 F. (Russell). The making of salt in large shallow lagoons or "salt-pans" along seacoasts, out of water let in at high tide and then confined for a time, is a common thing under the hot sun of tropical countries. The same process solar evaporation is used in many regions of brine springs. On some of the smaller coral islands of the equatorial Pacific, whose lagoons had become very shallow, there are now beds of gypsum sometimes two feet thick along with salt in places, that were made from the evaporating waters (Hague) , showing that the lagoon basins had passed through a salt-pan condition. The average composition of ocean water salts, in a hundred parts, has been deter- mined by W. Dittmar to be as follows: chlorine 55-292, bromine 0-188, sulphuric acid (S0 8 ) 6-410, carbonic acid 0-152, lime 1-676, magnesia 6-209, potash 1-332, soda 41-234, less the oxygen in soda and magnesia equivalent to the chlorine and bromine present combined with the sodium and part of the magnesium 12-493 = 100-00 ; or combining the acids and bases, the salts are : sodium chloride (common salt) 77-758, magnesium- chloride 10-878, magnesium sulphate 4-737, calcium sulphate 3-600, potassium sulphate 2-465, magnesium bromide 0-217, calcium carbonate 0-345 = 100-00. From these results Professor Dittmar calculates for the whole amount of salts in the ocean, as follows, the unit being 1,000,000,000,000 tons : sodium chloride 35,990, mag- nesium chloride 5034, magnesium sulphate 2192, calcium sulphate 1666, potassium sulphate 1141, magnesium bromide 100, calcium carbonate 160 = 46,283 ; also total bromine 87-2 (Dittmar), total iodine 0-03 (Kottstorfer), total rubidium chloride 25-0 (C. Schmidt). The lime alone varies appreciably with the depth. As compared with the amount of chlorine and bromine (the latter calculable as chlorine) , taking the amount at 100, the lime at surface (s), at medium depth (m), and in the deep sea (d) was found by Dittmar to be s, 3-0175; w, 3-0300; d, 3-0308. The amount of carbonic acid in the waters above what is required for calcium carbonate is large, especially that at great depths ; but it is CHEMICAL WORK. 121 not sufficient to convert all the calcium carbonate to bicarbonate. Deep sea water affords more or less free oxygen. (For Dittmar's results, see Rep. Chall. Exp., on ocean water.) The salinity or proportion of salts varies from dry winds, which tend to concentrate, and from fresh-water streams, which dilute. The area of maximum salinity in the north Atlantic is the Sargasso Sea, a region of calms between 25 and 35 N. and 30 and 20 W., where the specific gravity is 1-0285 ; while that of minimum is in the region of equatorial rains between 10 N. and the equator. In the south Pacific there is an area of maximum specific gravity (1-02719) about the Society Islands. In general the salinity decreases downward to 800 or 1000 fathoms, and then increases to the bottom. In the south At- lantic the specific gravity at the bottom is 1-0257 to 1-0259, but in the north Atlantic it is 1-02616 to 1-02632 at 2000 to 4000 fathoms (Buchanan). In the Baltic Sea, the salinity is reduced one half or more by the waters from the rivers, and the maximum specific gravity is only 1-0140. But in the Mediterranean, owing to evaporation and an average rainfall of but 30 inches, the specific gravity is 1-0280 to 1-030 ; and hence the amount of saline matters is about 3-9 per cent to 3-6 for the Atlantic. The following are analyses of two river waters, and of two mineral springs, from a paper by Professor C. F. Chandler. The Croton River (supplying New York City) is from a region of Archaean rocks ; the Mohawk, one of Lower Silurian shales, sandstones, and limestones (underneath) ; and the two mineral springs arise from the Potsdam sandstone. The amounts of mineral salts are of grains in a U. S. gallon (231 cubic inches = 57,750 grains) ; also mean of analyses of Arkansas Hot Springs, by R. N. Brackett (Ark. Geol. Survey), temp. 124 and 146-5 F. Potassium chloride. . . Sodium chloride 0-402 Sodium bromide ..... Sodium iodide Magnesium chloride. Potassium sulphate 0-179 Sodium sulphate 0-260 Calcium sulphate .... Magnesium sulphate. . Calcium carbonate 1 -648 Magnesium carbonate. . Iron carbonate. Silica 0-621 Organic, volatile Croton River, Mohawk, Congress Springs, Lithia Well, Arkansas N.Y. Utica, N.Y. Saratoga. Ballston. Hot Springs. 0-12 8-049 33-276 0-402 0-17 400-444 750-030 027 8-559 3-643 0-138 0-124 Na. phosphate 0-016 0-050 0-179 0-889 0-520 0-21 0-260 0-57 Na. Carb. 10-775 11-928 0-45 0-158 1-31 Li. Carb. 4-761 7-750 Ba. Carb. 0-928 3-881 Na 2 CO 3 0-04 1-648 4-60 143-399 238-156 7-15 1-100 1-71 121-757 180-602 1-13 0-340 1-581 FeS0 4 0-05 0-621 0-47 0-840 0-761 2-58 0-670 1-64 trace trace Total 5-038 10-68 1 700-895 1233 -246 2 11-88 Pure water has very feeble solvent action on rocks except in the case of gypsum and anhydrite, which yield 1 part to 400 to 500 of cold water. Quartz, feldspar, and other siliceous minerals are essentially unaffected. Only 2 to 10 parts of calcite are taken up by 100,000 parts. Opal, which is silica in the soluble state (like that of Diatoms, Sponge- spicules, Radiolarians), yields 12 to 15 parts to 100,000 parts of cold water, and much more to warm water. 1 The analysis afforded also 0'09 of alumina and iron oxide. 2 This amount contains also 0'867 strontium bicarbonate and 0'077 alumina; and both the Ballston and Saratoga waters afforded a trace of calcium fluoride and sodium biborate. The carbonates in these waters are reckoned as bicarbonates. The Congress Spring afforded 392'28J> cubic inches of carbonic acid to the gallon, and tbe Ballston, 426-114. 122 DYNAMICAL GEOLOGY. Professor A. Corsa subjected the rocks mentioned below, after fine pulverization, to the action of pure water at 65 F. for several days ; the weight dissolved was as follows : Gneiss, from Ragogna, 0-1250 per cent ; porphyritic retinite, from Monte Sieva, 0-0562 ; perlyte, of Monte Sieva, 0-0024; phonolyte, of Monte Croci, 0-3260; trachyte, of Monte Ortona, 0-0871 ; granite, of Montorfano (Lago Maggiore), 0-0727 ; granite, of Baveno (Lago Maggiore), 0-0906. Professors W. B. and R. E. Rogers found in their experiments (Amer. Jour. Sci., 1848), that under the action of carbonated waters, 0-4 to 1 per cent of the whole weight under digestion dissolved in only 48 hours. DaubrSe exposed orthoclase from Limoges in small fragments in a vessel containing twice as much water by weight revolving at the rate of 2550 meters per hour. The water in 8 days, after revolutions equivalent to a flow of 460 kilometers, contained 2-52 grams of potash per liter, along with 0-03 of alumina and 0-02 of silica. In salt water (water con- taining 3 per cent of NaCl) there was only a feeble alkaline reaction, incomparably less than with pure water. Water derives its chemical efficiency through the presence of such impurities as are ready to enter into new combinations. The most common of these foreign materials are carbonic acid (C0 2 ), humus acids, and alkaline ingredi- ents. When carbonic acid is present one part of calcite will be taken up by 1000 of water ; but in this case the material dissolved is not calcium carbo- nate, but calcium bicarbonate. Again, the presence of soda or potash gives increased solubility to silica in its soluble or opal state, the state charac- terizing organic silica. The least effect from moisture in rocks is diminished resistance to fracture or cohesion. Part of this is due to the lubricating effect resulting from the wetting of the grains, in consequence of which they slide over one another more easily than when dry. On this principle a grindstone is wet before using it. But in the case of wet rocks there is often, perhaps generally, a solution of a minute portion of some ingredient of the rock which becomes solid again on drying. For this reason, sand rocks, whether calcareous or siliceous, gradually harden at surface from alternate wetting and drying. The more prominent destructive effects of water, consequent on its solvent powers, are : the easy erosion of beds of gypsum ; the rapid removal of beds of salt ; and the injury to animal and vegetable life from encroachments of mineral and marine waters, and to marine life by its concentration on evaporation in shallow basins. The constructive effects are : the deposition of salt and gypsum in large beds ; and also the local superficial consolidation of rocks alluded to above. OXIDATION AND DEOXIDATION. On account of the very strong attraction between oxygen and nearly all the elements, and also because this gas is always at hand in air and water, it is the most prominent agent in the world's destructive and constructive chemical changes. CHEMICAL WORK. 123 1. Oxidation in inorganic materials, The effects that have special geo- logical importance are the slow oxidation of iron, manganese, sulphur, and some other elements, which takes place in the mineral constituents of rocks when water and air together have access. Little oxidation takes place under water. The iron of minerals undergoes easy oxidation when it is present in the protoxide state, FeO, or when combined with sulphur. The protoxide state is the unstable state of iron. In oxidizing it combines with one half more oxygen, and becomes the sesquioxide, Fe 2 3 . This iron oxide is the mineral hematite having a red powder, if free from combined water ; but, if containing water, limonite, which has a yellow or yellow brown color when powdered, if not before (page 71). The latter rust-colored oxide is like that which is produced when the metal iron rusts. But the rust may contain some carbonate besides the iron sesquioxide. In a similar manner, when a mineral contains manganese protoxide, MnO, the Mn tends to become Mn 2 3 or Mn0 2 , compounds that have a black powder. Black stains, and black crusts on marble and other rocks, after weathering, usually come from the oxidation of some manganese in the rock. The oxides FeO and MnO are unknown except in combination. But magnetite, Fe 3 4 , is common in disseminated grains in many rocks, besides sometimes constituting thick beds ; it often oxidizes slowly to the sesqui- oxide, Fe 2 3 , producing hematite or limonite. Again: the iron sulphides, pyrite and marcasite, each FeS 2 , oxidize readily, and especially the latter, as shown by Julien ; the iron, Fe, becom- ing FeO, if there is an acid ready to combine with it, but otherwise Fe 2 3 ; the sulphur, S, becoming S0 3 , and, with added water, sulphuric acid. This acid, with the FeO and water, may make the iron sulphate, copperas ; but it may combine also with Fe 2 3 , and make other sulphates. If there is limestone at hand, the S0 3 , or sulphuric acid, may combine with the lime and water, and form gypsum, and may thus make beds of gypsum. When pyrite and marcasite are mixed together, the marcasite makes oxidation easy (Julien). 2. Oxidation in organic materials, and other chemical changes. When life ceases, all organic materials tend to decay ; and in this decay, oxidation is the chief process, and oxides the larger part, or all, of the final results. Wood, when thoroughly dried, consists approximately of carbon (C) 49'66, hydrogen (H) 6-21, oxygen (0) 43-03, with traces of sulphur (S) and phosphorus (P), nitrogen (N) 1-10. Animal fats contain the same elements, and animal tissues the same with much nitrogen. In dried wood, the C, H, are atomically in the proportions nearly C 6 H 9 4 . In decay, the oxygen used may be that of the wood, or of the atmosphere or other substances. The C may combine with and make carbon protoxide, CO, the gas which burns with a blue flame in a furnace ; but it generally combines with 2 0, making the more stable and incom- bustible compound C0 2 , or carbonic dioxide (carbonic acid). The H may unite with O and form water, H 2 0. But instead of all the C combining 124 DYNAMICAL GEOLOGY. with 0, part, especially when the decomposition goes on under water, or where atmospheric oxygen is excluded, may combine with H and produce the hydrocarbon CH 4 called marsh-gas, because sometimes bubbling up through marsh waters ; it is the gas which burns and makes the flame of a wood fire. Other related hydrocarbons also might form. But the burning of this gas when complete ends in producing C0 2 and H 2 0. This is the final result when plants decompose in the air, except minor results from the nitrogen (N) and sulphur (S) present, among which are making, with the nitrogen, ammonia, NH 3 ; and, with oxygen, nitrous acid (N 2 3 ), and nitric acid (N 2 5 ) ; and making, with the sulphur, hydrogen sulphide (sul- phuretted hydrogen) H 2 S, and with oxygen, sulphurous acid (S0 2 ) and sulphuric acid (S0 3 ). In smothered combustion (as in making charcoal by burning wood under a cover of earth), nearly all the H and disappear as CO, CO 2 , and H 2 0, without a consumption of all the carbon ; and this happens when plants decompose under a complete covering of water, or earth, because this excludes the air and confines the changes to the elements of the plants ; and the more complete the protection, the greater will be the proportion saved of carbon and hydrogen, the combustible elements for the making of coal. With reference to the making of mineral oil or gas, it is to be noted that if the outside air is wholly excluded through overlying fine sediments, they may be produced by the direct decomposi- tion of woody tissues or of animal oils. Thus, if the carbon of the wood (C 6 H 9 4 nearly) combines with all the oxygen, making thereby 2 CO 2 , it will leave C^g , and 2 C 4 H 9 = C 8 Hi 8 , which is the composition of some mineral oil. So in animal oils, as oleic acid, CigH3 4 2 , on separating C0 2 , there would be left Ci 7 H 34 , one of the ethylene oils ; or from margaric acid, Ci 7 H 34 2 , the product would be Ci 6 H 34 , or a combination of marsh-gas oils. Fossil fishes are often numerous in coaly beds that afford much oil. (D., Min., 1868, p. 726.) In the change to ordinary bituminous coal the loss in the hydrogen of the wood, proportionally to that of the carbon, is about two fifths, and that of the oxygen about four fifths about 5-5 per cent of such coal (ash excluded) being hydrogen, and 12 to 15 per cent oxygen, with 80 to 81 per cent carbon. The carbonaceous products from the decomposition of plants and animals give the black color to soils. In wet soil, other acid products sometimes form, called humus acids, from the Latin humus, soil, or earth. The returning to the air of the constituents of a plant, by decay, in the form of carbonic acid and water, is restoring what was taken and used in the growth of the plant and balancing the account. The storing of part of the carbon and hydrogen in the rocks in the form of coal and mineral oil and gas was an abstraction of carbonic acid from the air, and commenced a debit account which use in combustion by man is doing only a little in the way of settling. Happily the world is better off for the purification of its atmosphere. 3. Deoxidation, or the abstraction of oxygen from a compound by any oxi- dizing substance at hand. Most deoxidation in nature is done by organic substances through the process of decay above described. The affinity in the carbon and hydrogen of the plant for oxygen is so strong that it will take it away from iron oxides or salts, and many other kinds. It may take from Fe 2 3 and reduce it to FeO ; so that if there is then an acid at hand for com- CHEMICAL WORK. 125 bination, as carbonic acid, it may take the FeO and make iron carbonate. Or if the acid is a humus acid, this acid may combine with the FeO, and, as such a compound is soluble, the waters may carry it to the marshes for deposition and re-oxidation. Since the compounds so made are colorless or nearly so, fragments of a plant in a rock may whiten the rock around them, thus making blotches in red sandstones, or a zone may be bleached around stems and roots. Also, the soaking down of soil waters may make a whitish streak along the top of the less permeable layers. In like manner iron sulphate or copperas, FeO.S0 3 .7aq (which oxidation of FeS 2 often produces, as above explained), may be deoxidized and reduced to FeS 2 ; that is, either pyrite or marcasite. Fossil wood may be replaced by pyrite or marcasite as decomposition goes on, and shells may be changed in like manner, as acid waters at hand dissolve and remove the calcareous material. Calcium sulphate, or gypsum, is, by similar deoxidation, converted into calcium sul- phide, CaS ; zinc sulphate, into zinc sulphide, ZnS, the mineral, sphalerite ; and lead sulphate, into lead sulphide, PbS, which is the common lead ore, galena. After the deox- idation of a sulphate, as gypsum (calcium sulphate), to calcium sulphide, the re-oxidation of the sulphide may take place, and hydrogen sulphide (sulphuretted hydrogen) may result through the agency of the water at hand, thus : Ca takes oxygen from the water, making CaO, or lime (which may combine at once with CO 2 to make CaO.C0 2 , or calcium carbo- nate), and the sulphur, S, takes the hydrogen thus set free from the water, making SH 2 , or hydrogen sulphide (sulphuretted hydrogen) ; for CaS + H 2 = CaO + H 2 S. This is the ordinary process by which the gas of sulphur springs is made, as for example those of western New York and Virginia. By the oxidation of the hydrogen of the hydrogen sulphide making H 2 0, or water, tne sulphur, S, becomes deposited. This is a very prominent source of sulphur; and ii accounts for its frequent association with gypsum and limestone. Further, hydrogen sulphide, SH 2 (sulphuretted hydrogen), by action on zinc sulphate, will deoxidize the sulphate and make zinc sulphide ; on iron sulphate, it will make an iron sulphide ; on lead sulphate, lead sulphide. But under warm and moist conditions the sulphur may oxidize and make sulphuric acid, S0 3 +water; and some sulphuric acid springs in New York have this source. Gypsum may be formed by such waters if limestone is within their reach. Pfaff states that at depths in water under a pressure of 40 atmospheres anhydrite will probably form, and not gypsum. Anhydrite is gypsum minus the water. It may be added that sulphurous acid, S0 2 , is formed by the combustion of sulphur (as in volcanoes) ; and when this gas comes into contact with hydrogen sulphide (SH 2 ), the sulphur of both is deposited, the oxygen and hydrogen combining to form water ; and this is one source of the sulphur about volcanoes. With heat, carbon deoxidizes iron oxide and oxides of other metals, producing the pure metal. 4. Destructive effects. Since nine tenths of rocks not limestones contain one or more of the common iron-bearing silicates, pyroxene, hornblende (or other species of the hornblende family), or black mica, and almost all rocks have a sprinkling of pyrite or marcasite, the oxidation process is all-pervading in its destruction. The presence of water and air being necessary, the more porous the rock, the deeper and more rapid the decay. The rocks where the 126 DYNAMICAL GEOLOGY. destructible mineral is a chief constituent become covered with, a rusty crust which is ever encroaching inward; and this crust is slowly reduced to a rusty earth, having parted with all soluble ingredients ; or, losing the rusting mineral, it finally falls to earth or sand. A porous granite or gneiss contain- ing black mica may become deeply rusted, and finally reduced to a weak mass of quartz and unaltered feldspar, good material for a granitic sandstone. If marcasite or pyrite is present in any rock, there is not only oxidation, but corrosion from the sulphuric acid that may be formed, which attacks any lime present in the minerals of the rock, or any magnesia, or potash, or soda, or alumina, and makes sulphates with each. The aluminum sulphates are alums, but strictly so only when potash, soda, or some other base is also present. Some beds of shale containing iron sulphide are impregnated or interlaminated with alum which has been thereby made, the shale affording the alumina of the alum. Limestones, even the whitest of marbles, often contain a trace of iron or of manganese in combination, and occasionally masses of the iron car- bonate, siderite. The iron carbonate, unless in a massive state, readily oxidizes ; and so also does the iron of the limestone on exposure for a few months ; and this is a commencement of the change in the whole mass to limonite. The work in progress is illustrated by Fig. 132, representing an 132. 133. Impure limestone decaying to limonite. Same, with calciferous schist. D. impure ferriferous limestone as it appears where the alteration is going on at the Amenia Ore-pit, IST.Y., southwest of Salisbury, Conn. ; and Fig. 133, the same, with the calciferous schist adjoining also changing. If one per cent of iron is present, a limestone will rust and decay ; if as much man- ganese is present, it will become covered with black stains. f The massive siderite changes slowly over the surface and in rifts. Limonite the yellow-brown oxide of iron, or yellow ocher is the most common result of the oxidation; but hematite, of red-ocher color, is often produced in warm and rather dry climates. Nearly all red, yellow, and brown rocks, sand-beds, or earth-beds, owe their color to iron in one of these two forms. Oxidation of the iron in pyroxene gives the yellow-brown fronts to trap bluffs not their gray and black tints, which are due to lichens ; and has spread delicate surface shades of red and yellow over sandstones in the Yellowstone Park, and other dry parts of the Rocky Mountains, through the oxidation of the little iron inside. CHEMICAL WORK. 127 This oxidation process, and other methods of decay, go on with greatest rapidity in the fissures of rocks, below a surface of soil, because the descend- ing surface waters keep them almost continuously wet ; and it is under such circumstances that a rock which is much fissured or jointed becomes re- duced to a pile of great bowlders with rusty earth between, as illustrated in the figure annexed. The balls of rock here represented are very common in decomposing rocks from granites and trap to sand- stones. They are simply a result of surface decay along the many planes of fracture (Fig. 134). The decay or oxidation at first produces a thin discolor- ing of adjoining surfaces, as in the lower part of the figure; and this continues, eating off the angles, which are attacked from three directions, until a bluif of solid rock becomes apparently a pile of great bowlders. With the progress of the alteration, the discolored portion becomes banded with yellow and brown ; and as it deepens, the outer part of the spheroid sometimes separates in concentric shells, precisely corre- sponding with the concentric structure of a concretion. But these concentric shells are due to the decay that is in progress ; and apparently to alternations in the work of decay dependent on climate and the capillary action above explained. Bounded stones or bowlders are very often so made. After separation from the pile, and therefore from exposure to almost permanent moisture, the masses may decompose outside with extreme slowness. 5. Constructive effects. As the process is a means of reducing the hardest rocks to earth and sand, it aids in preparing material for new rock-making, and also in supplying earth and sand for soil and fertility. Without it, and one other associated process mentioned beyond, the earth would have had very scanty geological records and only low-grade life. This agency has produced, or aided in producing, a large part of the great and valuable iron ore beds of the world's history, from Archaean time onward. The limonite ore beds (often called by miners " hematite " beds) are among the products. They occur of great size and value in West Stockbridge, Mass., Salisbury, Conn., Amenia and elsewhere in New York, in eastern Pennsylvania, western Virginia, and farther south to Alabama, as a result of the oxidation chiefly of a ferriferous limestone, and of any iron carbonate the limestone may contain. In the formation of the iron oxide, carbonic acid is set free, and the weakened calcareous rock is hence readily removed by percolating waters ; hence great cavities are made by the process, ready to receive the ore as it is produced. Any slates or schists adjoining are also destroyed by the action. Iron sulphides have been the source of similar beds, but such ore is likely to contain some sulphur. The Amenia ore bed is a good place for studying the formation of the ore from both a ferriferous limestone and a massive iron carbonate. These ore-beds, although superficial, cannot be 128 DYNAMICAL GEOLOGY. affirmed to be modern ; for they have probably been in progress ever since the land first emerged from the ocean so that air and water could begin the work. In the destruction of the iron-bearing minerals of surface rocks, the iron oxide combined with a humus acid is often carried into marshes to make " bog iron ores." The ores thus formed have much value, although likely to contain phosphates as impurity, because of the animal and vegetable mat- ters that live and die, or find burial, in swamps. The consolidation of beds of sand and gravel, or layers of rock, is another of the constructive effects of the iron oxide that is distributed through the material of the beds. In the simplest form of it, the waters, filtering through soil and gravel, take up enough oxide of iron to cement a bed of pebbles lying at a lower level on another layer sufficiently close in texture to hold the water and give the iron a chance to deposit; and this is one way in which what is called hard-pan is sometimes made. The underlying impervious bed is not absolutely necessary to the result, although promoting it. The pebbles wet with the ferruginous waters, when they dry in times of drought, take a deposit of iron ; and this process may end in complete consolidation. In other cases the oxide is produced throughout the deposit under the action of infiltrating waters, and slowly becomes a cement as it solidifies. This mode of consolidation without aid of heat is not the most common nor the most efficient. The beds of sulphur of the world have been made by the two processes mentioned on page 125, and chiefly the former. HYDRATION, OR THE CHEMICAL ABSORPTION OF WATER. Many minerals take up water on "weathering." But this usually is an accompaniment of commencing decomposition. An example of simple hydration of geological importance is the change of anhydrite (CaO.S0 3 ) to gypsum (CaO.S0 3 .2H 2 0). As the minerals are very unlike in cleavage, and both occur in large beds, the change is strikingly noticeable. CARBONIC ACID, HUMUS ACIDS. 1. General action. Carbonic acid (C0 2 ) is ever present in the atmos- phere, of which it constitutes 3 parts in 10,000 by volume, and in all rain water, river water, and sea water. It is often given off by mineral springs, and occasionally escapes in large volumes from fissures in volcanic regions. In the northeast corner of Yellowstone Park is " Death Gulch," where the gas rises freely from the waters of Cache Creek, to the destruction of bears and other wild animals. Butterflies and other insects, besides skeletons of bears, elk, squirrels, etc., attest to its deadly character (W. H. Weed, 1889). Death's Valley in Asia Minor, and the Dog's Grotto at the Solfatara near Naples, are other localities of escaping carbonic acid. CHEMICAL WORK. 129 Carbonic acid is given out in respiration, and is a product of animal and vegetable decay ; and by this means it becomes distributed through the air and waters. The humus acids, ampng the results of vegetable and animal decay by oxidation, occur in all damp soils in which such decay is going on. The action of these acids has been studied by A. A. Juiien. 1 They are effective especially through tueir affinity for iron protoxide, magnesia, lime, soda, potash, and some other protoxide bases. a. In water, carbonic acid takes up calcium carbonates from any calcareous material, whether in the state of limestone, or in other conditions, to make calcium bicarbonate for transportation. On evaporation, the bicarbonate again becomes calcium carbonate. The amount taken up is increased by the presence of magnesium or sodium sulphate in the waters (Hunt). The Mammoth Hot Springs contain 0-6254 parts of calcium carbonate in 1000 of water, which is over 4 times as much as pure water saturated with carbonic acid will take up (Russell). b. It takes the bases potash, soda, lime out of a feldspar, thus destroying the mineral to as great a depth in a rock as the carbonated water and air can penetrate, and reduces it to clay. This is true especially of the potash-feldspars, orthoclase, and microcline. The same work is done by the humus acids. The clay results thus : Ortho- clase consists of silica, alumina, and potash. In the change it loses the potash and part of the silica, and becomes silica, alumina, and water. Thus the compound, K 2 0. A1 2 3 .Si 6 0i 2 , becomes H 2 O.Al 2 03.Si20 4 , and 1 of water. Half of the water (H 2 0) received replaces the potash (K 2 0) lost. c. Carbonic acid decomposes other minerals in a similar way, taking out the protoxide bases. It may thus form a soluble iron bicarbonate in waters, which streamlets may convey to marshes. But only a trace of this iron salt can be held in waters under the existing atmospheric pressure. The humus acids also make, with iron, soluble salts, and do, at present, the chief part of such transportation for the making of bog ores. On the evaporation of the solvent waters, the iron in each case is usually deposited as hydrous sesquioxide or limonite. d. Further : it is supposed that carbonic and humus acids may aid in the oxidation of the protoxide-iron of a mineral by bringing it to the surface of a mass of porous rocks, so as to make the oxidation possible. 2. Destructive effects. For the reasons stated carbonated water con- taining humus acids has done a vast amount of eroding work. (a) Draining out by infiltrating waters. The lightest work is the drain- ing of any soluble ingredient out of a rock. Calcareous grains are thus drained from a porous calcareous sandstone, or quartzyte, increasing its porosity. So also calcareous fossils are removed from rocks that admit infil- trating waters, leaving the rock cellular. When a crystalline limestone or marble, a porous rock, consists of dolomite, but contains mixed calcite, all the calcite grains are drained out because they are the most soluble, and the rest are left to fall to loose sand, an effect exemplified in many places over Canaan, Conn., and Berkshire County, Mass. If the fossils of a lime- stone are made of calcite and aragonite (the latter the prismatic calcium carbonate), the aragonite portion is taken away a fact first reported by Sorby. Shells of the kind referred to are those of the genera Pinna, Mytilus, 1 On the reaction of the humus acids see A. A. Julien, Rep. Amer. Assoc., 1879. DANA'S MANUAL 9 130 DYNAMICAL GEOLOGY. Spondylus, Patella, Fusus, Purpura, and Littorina, in which the inner pearly layer is aragonite, and the outer calcite. The shells of most Gastropods and of Cephalopods are aragonite ; and Corals, including the Millepores, are mainly so ; while shells of Khizopods, Echinoderms, and Brachiopods consist of calcite. Further, if the limestone contains iron or manganese combined with the calcite, carbonated water will bring the iron to the surface, or the iron car- bonate, or the manganese, for oxidation, weakening and discoloring the rock. The action on feldspar, above mentioned, is a common means of destruction in the case of granites and related rocks. (b) Process of draining limited. -But it is also to be observed that these effects occur only so far as the rocks are porous. The fossils of compact argillaceous sandstones and shales common kinds of fossiliferous rocks and some dating from the Cambrian are seldom drained out or injured at all by infiltrating waters, except when near the surface. The iron and manganese taken out of some crystalline limestones are removed only for a short distance inward ; but the process destroys the limestone as it eats in, and is thus enabled to erode farther. Deep below the surface the same rocks are solid and not discolored. All deep-water rocks are moist, but the moist- ure is ordinarily stationary unless a surface drought reaches downward, or an invasion of heat comes upward from below, when the moisture thus lost may be later replaced. Even beds of salt in subterranean rocks are not dissolved away. (c) Surface erosion. Waters containing carbonic acid or hurnus acids eat away the surface of solid limestone, fluting precipices, widening crevices, excavating caverns. They often leave calcareous fossils projecting slightly above the surface, and develop with great perfection silicified kinds. The length of the caverns thus made in the Carboniferous limestone of Kentucky, Making of caverns in limestone. Shaler. a rock 200 to 1000 feet thick, is estimated by N. S. Shaler to amount to 100,000 miles. The work is begun by the descent of waters along joints in the rock, whenever there is a chance for discharge below, by running down or trickling along between layers of the limestone. The process and result are illustrated in the above figure by Shaler. In the movement of the waters, the fissure or joint (B) becomes enlarged to a "sink-hole," and exca- vation begins between the layers. The end is a great cave, having, it may CHEMICAL WORK. 131 be, its spacious chambers, high water-falls, and free-flowing rivers. The flowing waters sometimes work also by abrasion ; but there is usually little loose material to transport for the purpose of abrasion. In a similar way limestone cliffs have been chiseled into ranges of turrets, and deep recesses and channels made for rivers through lime- stone strata. The excavation of the lagoon basins of coral islands has been attributed erroneously to erosion by the carbonic acid of the sea water. (d) Except for surface erosion, limestone consisting of pure calcite, free from iron sulphides, is a durable rock, whether uncrystalline or crystalline, as in the case of the Carrara marble, of which such marvelous structures as the Milan cathedral have been made. But a magnesian limestone or dolo- myte, when crystalline, is often easily destructible, because, as already stated, the porous rock is likely to contain disseminated calcite ; and as this is more soluble than dolomyte, percolating waters carry it off, leaving the rest in the state of sand a bad condition for the marble temple that may be made of it. The presence of the calcite can be detected only by observing whether, at any exposure of a layer in the region of a quarry, it is turning to sand. Polished limestone marble containing any chert or other hard mineral, if employed in out-door ornamentation or on monuments, is sure to weather rough and become unsightly, and the chert may be made to stand out in ragged points or knobs. Even the vertical movement of the atmosphere over polished marbles will in time take off or dim the polish. (e) Since carbonic acid attacks feldspar as well as other minerals, this agency, and that of oxidation, leave scarcely any kind of rock safe against destruction. Those are safest that are free from iron sulphides, and especially those that are so fine-grained and compact that water cannot gain access. Hence, the method of testing rocks for porosity by ascertaining how much water they will absorb in 24 hours is excellent. Some slate rocks are very durable because of their fine grain and the absence of any soluble minerals. Some granites absorb little water, some very much ; and the latter are easily destructible. 3. Constructive effects. (a) Calcareous deposits. The most familiar deposits of this kind are the stalactites and stalagmites of caverns, dripstone formations ; so-called because made by the calcareous waters dropping from the roofs. The "Gibraltar rock" is stalagmite. Still more interesting are the travertine or tufa deposits of streams. Leaves, nuts, and stems are often petrified by calcareous waters. The travertine of Tivoli, near Rome, constitutes a large deposit along the Anio, whose waters are there strongly calcareous. Along Gardiners Kiver, in the region of the Yellowstone Park, thick limestone deposits have been made, as is well illustrated and described in the Reports of Hayden's Geological Survey of the Territories. The calcareous waters, in descend- ing the slopes of the hills, have made a series of parapets at different 132 DYNAMICAL GEOLOGY. levels, inclosing basins, over which the water drips or plunges on its way to the bottom, as illustrated in Fig. 136. Travertine is usually somewhat cellular and concretionary in structure if not in exterior forms, unlike the even-grained material of ordinary limestone. 136. Calcareous formations. Mammoth Hot Springs, Gardiners River. Phot, by Jackson. About the lakes of the Great Basin calcareous deposits have unusual extent and variety of forms, rising often into groups of rounded columns, 137. Tufa deposits, Lake Mono. I. C. Russell. towers, domes, and other shapes. One example, taken from I. C. Russell's Report on Lake Mono (1889), is illustrated in Fig. 137. These deposits are also abundant in other parts of the Basin. CHEMICAL WOKK. 133 Some of the travertine deposits of Gardiners Eiver and elsewhere are a result of the growth and secretions of Conferva-like plants, as explained bv W. H. Weed. In the Lahontan and 138. Mono basins, as described by King and later by Eussell, he material has often a crystalline form, the origin of which is yet unexplained : this variety is the tliinolite of King. A common form is represented in Fig. 138. The beautiful trans- lucent limestone of Te- cali, Mexico, often wrongly called onyx, because banded in colors when polished, is a calcareous deposit failing of the coarse and irregular grain of travertine. (b) Consolidation. Of still greater geological range is the cementing work done by calcareous waters. Ordinary sea water, especially where shells and corals abound, consolidates sands made from coral and shell into limestone. The beach sands, drifted sands, and sands over the reefs, when drying from exposure to the air, become cemented in this way. Conglom- erates are also made of broken corals, shells, and calcareous or other pebbles, and breccias, in this, as in other ages, out of a talus or any accumulation of limestone blocks. The under-water calcareous sands, as those about coral reefs, also become cemented by the same means, but into a compact limestone like ordinary limestones, showing usually no sand-like grains in the texture. Thinolite : from Lake Mono. I. C. Russell. (c) Dolomyte-making. Even dolomyte, (sCaJMg) 3 C, owes its origin at times if not always to the conditions that exist in the history of coral reefs when the magnesia, required to make the calcareous grains magnesian, could have had no source but the ocean. One case of the kind is reported by the author (1849) from the island of Metia, an elevated atoll north of Tahiti (Corals and Coral Islands, page 393). The rock is a compact white limestone. An analysis by B. Silliman proved that it contained 38-07 per cent of magnesium carbonate, the rest being calcium carbonate. The very fine texture of the rock indicates that it was made of the finest of calcareous ooze or mud, such as forms through gentle wave-action in shallow lagoons ; and in such lagoons, mainly shut off from the sea, and therefore in a "salt-pan" condition (page 120), the concentrated brines contained the magnesium chloride and sulphate in a state that favored the formation of dolomyte. 134 DYNAMICAL GEOLOGY. The change, if produced through the magnesium chloride (MgCl), required the removal of Ca by the chlorine of an equivalent amount of Mg. If this is the true theory of dolo- myte-making, then great shallow areas or basins of salt-pan character must have existed in past time over various parts of the continental area and have been a result of the oscilla- tions of the water level. Such magnesian limestones contain few fossils, partly because of the fine trituration, and partly, no doubt, because of the unusually briny condition of the waters. The frequent alternation of calcite and dolomyte strata would indicate alternations between the clear-water and salt-pan conditions. Dolomization, in the case of such beds, has often taken place after partial or complete consolidation ; for many dolomytes are exceedingly porous, because of the diminished bulk of the dolomyte one eighth to one tenth. T. S. Hunt made the porosity of several Canadian Lower Silurian dolomytes, 10 to 13^ per cent (1866). Local cases of alteration are well known. Adolf Schmidt mentions such at the lead mines of Missouri, which he attributes (following Bischof) to the action of magnesium bicarbonate. In a memoir on the famous dolomyte region of the Tyrol, Dolter and Homes, geol- ogists of Vienna, discuss this subject at length, and reach the following conclusions: (1) Some large limestones, weakly dolomitic, may have been made out of those organic secretions which contain a little magnesia ; (2) minor cases of the production of dolomyte are due to the alteration of limestone through the introduction of magnesium carbonate ; but (3) the larger part of dolomyte formations, whether more or less rich in magnesia, have been formed from organic calcareous secretions through the action of the magnesium salts of sea water, especially the chloride. (d) Making of day and soil. Pure white clay, or kaolin, used in mak- ing porcelain, is sometimes in strata of wide extent ; and the common impure river-valley clays, employed in brick-making and coarser pottery, have no less value. One of the largest kaolin beds in New England, at New Marl- boro, in Berkshire County, Mass., was probably made by the decomposition of the orthoclase that was disseminated through quartzyte, and its removal by percolating waters to the bed of a streamlet; for in other localities in Berkshire this result is now going on from the same quartzyte. The absence of black mica and other iron-bearing minerals insured its being white. (e) TJie blanching of red and rusty rocks by waters containing carbonic acid and organic acids or materials is a common and important effect. Colored clays are drained of their iron oxide and whitened by percolating waters. A deeply rusted block of basalt or granite may thus be made to have a white exterior an inch or more deep. (/) Again, the impurities of a limestone are sometimes made available for soil, by the continued action of carbonated waters, and the removal thereby of the calcareous part. Shells and corals contain about O5 per cent of impurity, consisting chiefly of iron oxide and alumina ; and the action of the rains over the hills of coral sand-rock on Bermuda, through centuries past, has left a residuum of red earth which is the soil of the island, as Wyville Thomson suggested. The red ooze or mud over much of the ocean's bottom below 2500 fathoms is due chiefly to the removal, in like manner, of the calcium car- bonate of the Globigerinae and other Rhizopods, in consequence of an excess of carbonic acid in the bottom or abyssal waters. The life of the sea-bottom CHEMICAL WOKK. 135 has no accompanying vegetation to use up the carbonic acid of respiration and decomposition, and this gas would therefore become accumulated in its depressions. SILICA: QUARTZ AND OPAL SILICA. Silica in solution does the greater part of its geological work when aided by heat. Still much consolidation has been carried on by cold solutions, especially solutions of alkaline silicates, as potassium and sodium silicates. The former of these silicates is the waterglass of the shops, K 2 0. 4Si0 2 , much used for making artificial stone and for other purposes. Waters percolating through beds of volcanic ashes, by decomposing the feldspar present, take up silica and deposit it in the form of quartz and opal, making silicified wood and the finest of opals. In this way petrified forests have been made. In Napa County, California, according to the descriptions of 0. C. Marsh, in 1871, one of the prostrate trunks of the silicified forest, exposed to view by the washing away of the tufa and tufaceous sandstone, was 63 feet long, and 7 feet in diameter. In the Yel- lowstone Park, according to W. H. Holmes, in his paper of 1878, the forest trunks, from one to ten feet in diameter, are at several horizons in a deposit of tufa 5000 feet thick, indicating successive disastrous showers of volcanic ashes, at intervals long enough for the growth of a great forest. In Arizona, near Carrizo, in Apache County, there is a noted locality which affords aga- tized wood of great beauty, which has been well named Chalcedony Park. In such cases heat from hot springs may often have given aid ; but it is probable that the temperature in the Yellowstone region was only that of the descend- ing volcanic ashes and accompanying rainfall. The decomposition of the out- side of trap sets silica free, which coats the surface with a whitish pearly layer of opal silica. Beds of Diatoms and other siliceous organisms are sometimes converted by percolating waters into opal. The siliceous organisms that were originally disseminated in the calcareous materials out of which limestones and chalk were made were the source of the flint and chert, that occur in these rocks. Siliceous sponge-spicules constitute a chief part. This was early proved for flint, and for Lower Devonian and Lower Silurian cherts ; but it has been proved to be true, by Dr. G. J. Hinde, for cherts or flints of all geological ages, whatever the size of the beds. The silicification of wood referred to above is in part due to silica from siliceous organisms. The amount of silicification of fossils that has taken place in cold rocks makes it probable that more consolidation is due to the process than has been supposed. Cases of the hardening of the exposed surface of a sandstone or quartzyte, making a hard crust, described by M. E. Wadsworth (1883), have an important bearing on the subject. He speaks of a block of white Potsdam sandstone, in Wisconsin, which was friable on the protected side, but on the side exposed to the prevailing storms was nearly a quartzyte ; and a surface freshly exposed by fractures was found, six months later, to be much 136 DYNAMICAL GEOLOGY. indurated. The St. Peter's sandstone afforded similar facts. In one case the cavities over the exposed surface had a lining of quartz crystals, while the rock a few inches below had the common friable character. The effects were connected in some way with weathering processes. In some cases of the kind the silica may have come from the decomposing action of percolating acid waters on feldspar grains sparsely disseminated through the rock. Over the cold bottom of the ocean some silicates have been formed. Among them are masses or concretions of bronzite, a silicate of magnesia and iron related to pyroxene, and small crystalline groups of Phillipsite (Christianite). At depths of 2200 fathoms and over, the pressure on the bottom is 5000 to 12,000 pounds to the square inch ; and this may favor the production of silicates, where the siliceous parts of Sponges, Diatoms, or Radiolarians abound, with the results of the decomposition of volcanic dust and pumice. Another silicate of common occurrence, forming in shallow water as well as in deep, is the green-sand called glauconite, a hydrous silicate of iron and potash. CHEMICAL WORK OF LIVING ORGANISMS. Respiration in animals, and also in plants, is a means of introducing oxy- gen from the air to carry on processes of oxidation among the elements in the structure, and the excretion of carbonic acid is one prime result. The growth of green plants, however, depends on a deoxidation process, the car- bonic acid of the air being decomposed in the sunlight by the green color- ing-matter (chlorophyll) of the plant, its carbon forming the food of the plant and its oxygen being set free. Plants of the Fungus division (Mush- rooms and the Microbes) are not green (have no chlorophyll), and cannot get their food directly from the carbonic acid in the air. The chemical work of life of most geological importance, apart from the making of coal and related products, is that carried on by the lower plants ; and only this is here briefly considered. Plants, and especially the lower Cryptogams, contribute chemically to geological change through their roots or the fibers with which they come in contact with rocks. The acidity of roots is often very decided, as is manifest from the furrows they make in the surfaces of stories, and especially in limestones. Boots of plants germinated in sand over a slab of marble leave an imprint on the marble. Professor Storer observes that " it is to be noted that this action by chemical corrosion through the roots is incessant and continuous." The lichen Stereocaulon Vesuvianum, which grows on rocks, and among them on Vesuvian lavas, affords one ninth its weight of ash ; which from one Vesuvian specimen, according to Eoth, contained silica 46-41, alumina 19-67, Fe 2 3 6-88, FeO 4-17, magnesia 5-23, lime 10-53, soda 2-02, potash 4-09 = 99-00. For other analyses, see page 75. The microbes, or Bacteria, are at the bottom in much of the world's chem- istry. They do not get food from carbon dioxide, but, like true Fungi, find it in other compounds : for example, those consisting of carbon, hydrogen, and oxygen, as sugar, starch ; or those containing these elements and nitro- gen, etc., as albumen, muscle, or even a mineral sulphate; they taking the part of the compound required for food, and leaving the rest to CHEMICAL WORK. 137 form other products, at the same time usually giving out carbonic acid as a result of the plant's assimilation. The processes of oxidation and deoxi- dation are carried on by them ; and it is a question whether, in the particular cases mentioned on the preceding pages, the changes are not dependent on the presence of microbes. They set sulphur free from sulphates (genus Beggiatoa) ; make ammonia and nitrates (Micrococcus nitrificans) , deoxidize nitrates and other salts ; aid plants in taking up nitrogen through the roots ; probably aid animals in their digestive processes, besides causing some of their diseases; they are the basis of all processes of fermentation, and are concerned fundamentally in animal putrefaction and vegetable decay. Tyndall proved that flesh would not decay if shut away from Bacteria the strong affinities of its elements being unable to take a start without help from these minutest of plants. The Bacteria are the smallest of workers and among the largest of producers. In garden earth which is free from compost, as T. Leone found, the nitrification process converts the nitrous acid into nitrate ; while, on adding compost, the nitrate is deoxidized, and ammonia is given out ; or in gelatine or other proteid substance and water, the organic substance is rapidly oxidized, attended by denitrification and the production of ammonia. Bacteria liquify muscle and coagulated gelatine, and, according to Brunton and Mac- fadyen, by producing a peptone-like solvent ; and the same kinds produce fermentation in starch and similar non-nitrogenous carbo-hydrogen materials. This organic source of nitrates explains their occurrence in the earth of caverns, or beneath sheds, and in other covered places ; also of the loosening of the sands of sand- stones in such places an agency that may in time cause a vast amount of degrada- tion and removal. The native nitrate is usually either sodium or calcium nitrate, but sometimes potassium nitrate. The latter, which is salt-peter of the shops, is usually made from the others. In Kentucky caves the calcium nitrate occurs, the caves being in limestone. Sodium nitrate exists in the district of Tarapaca, northern Chile, over a great extent of surface, 3300 feet above the sea, in beds several feet thick, which have a covering of earth and a layer of gypsum, and contain some common salt. Moreover, underneath the bed occur common salt, glauber salt, gypsum, magnesia alum, and large quantities of borates ; all of which indicate deposits from hot springs or evaporated sea water. But the source of the nitrate remains unexplained. This Tarapaca region of western South America is much like the Great Basin of North America in position, dryness, and saline deposits. MECHANICAL WORK OF CHEMICAL PRODUCTS. In oxidation and other processes yielding solid products, particles of the new material, when formed among the grains of the surface portion of a rock, or in its rifts, act like growing wedges in loosening and detaching the grains, and opening and extending rifts. The following figure represents a piece of quartzyte from Canaan, Conn., divided up, or septated, by the oxidation process. It looks like breccia, in which limonite is the cement ; and speci- mens from the region were long so considered. But it was produced by the formation and infiltration of limonite. The rifts were thus widened into 138 DYNAMICAL GEOLOGY. 139. Quartzyte septaria. D. '84. 140. rents; moreover, the iron oxide spread either side, staining the rock, pro- ducing the appearance of very wide rifts. Along one rift there is an open space from the loss of grains, and in it a crust of newly formed quartz crystals. The process often results in pushing the pieces out of place. Where saline efflorescences as alums, ni- trates, alkaline carbonates, or chlorides are produced in the pores of a sandstone, the surface grains are successively pried off. Much denuda- tion is thus produced, especially in arid regions. The process often makes a series of excavations along the front of bluffs. The process goes on most actively in covered places and during the heat of the day. A shale often has its laminae separated by layers of the salt or oxide, and fragments detached. Displacement by intrusion of crystalline material is a common process. The following figure illustrates a case in which crystals of tourmaline in mica schist are pushed apart at planes of fracture by intruding quartz (the dotted portion) from a siliceous solution. After the first deposit of quartz within the fracture, the additions were made between this deposit and the adjoining part of the crystal, and so the wedging apart went on. A. H. Worthen has described Crinoids, from the Keokuk limestone, as split open and enlarged in this way, and one Barycrinus that was thus made a foot in di- ameter. The tubular stems are increased four to six di- ameters in the process. The siliceous solution supplying the quartz of the Keokuk limestone was probably not heated. The displacements may be great when large masses of a rock undergo change to a kind requiring additional space. In the change of a bed of anhydrite to gypsum the increase of bulk, due to the added water (page 128), is nearly 60 per cent. Dividing the atomic weight of anhydrite, which is 136, by the specific gravity, 2-95, gives 46-1 for the bulk ; and that of gypsum, 172, by its specific gravity, 2-33, gives the bulk 73-8, making thus the gain in bulk from 461 to 73-8. The change is hence attended by a breaking and displacement of any overlying beds of rock. In the change of calcite to true dolomyte, (JCa-J-Mg) CO.,, there is a diminution in bulk of one eighth per cent (or one tenth, if the composition is (-f-Ca -JMg) C0 3 ) ; which, Broken crystals of tourmaline displaced by intruded quartz, Lenox, Mass. D. '85. CHEMICAL WORK. 139 if it takes place in a bed of calcite after its consolidation, would cause frac- tures, or make the rock porous and thus capable of holding much mineral oil (page 134), as in the Findlay oil region of Ohio. CONCRETIONARY CONSOLIDATION. The methods of consolidation that have been mentioned in the preced- ing pages are (1) by calcareous waters ; (2) by ferruginous waters ; (3) by siliceous solutions. Limestones, and rocks only partly calcareous, have been consolidated almost solely by the first of these methods. The second method is feeble in its results, and occurs in gravel deposits. Rocks that are colored by iron oxide, and appear to have a ferruginous cement, have usually been solidified by the third method. Consolidation is often commenced or attended with concretionary consoli- dation, or accretion around centers throughout the mass, as illustrated on page 97. Isolated concretions often form in deposits of earth, clay, or other material, when they contain disseminated calcareous grains (derived from ground shells, or any other source). Percolating waters, aided by the car- bonic or humus acids which such waters are likely to contain, dissolve the grains and deposit the material, in a drying time, around grains, or any small object, as a nucleus. In like manner, concretions of limonite and iron carbonate are made, if any ferruginous grains or any decomposable iron- bearing mineral is present. Occasionally other materials make disseminated concretions. The form of the concretion is not owing to any central control of the molecular deposition, but to the regular progress of the superficial accretion, and to the rate of supply of the mineral solution in vertical and horizontal directions, together with the shapes of the nuclei. The growth of the concentric forms above described is peripheral. There is also centripetal consolidation, or from the exterior inward. It commences outside, owing to outside evaporation and the consequent deposition of the concreting agent. The agent is commonly ferruginous. This process of outside drying is exemplified by the drying away of a spot of milk two inches or so in diameter on a slab of stone (as observed by the author) : the evaporation goes on at the outer margin, and makes there the first ring, capillary attraction inside of this ring contributing material toward it; this outer ring completed, another ring begins and forms at the new outer margin of the milk-spot; and so ring after ring forms, until the spot of milk is reduced to a series of whitish rings. On the same principle, shell after shell may form in a sand-bed penetrated with a ferruginous solution, because drying is gradual from the outside ; or there may be a single outer shell, with loose sand inside ; or a central ball in the loose sand. The center of the concretion may originally have been a piece of the decomposing iron- bearing mineral which afforded the ferruginous solution. The concentric rings of ferruginous coloration in Fig. 141 had probably 140 DYNAMICAL GEOLOGY. this mode of origin. The two sets of rings were either side of a crack in the rock, and had together a diameter of about twenty feet. Fig. 142 represents concentric areolets between mud cracks in an argilla- ceous shale, made by siliceous waters at the time of the consolidation, when the mud cracks were likewise filled with quartz, a layer of quartz being 142. 141. Concentric discoloration, Illewarra, N.8.W. D. '49. Concentric structure, Australia. D. '49. deposited against each wall. Whether in this case the concentric consolida- tion was centrifugal or centripetal is not ascertained. Seashore wear of the rock brought the structure to view. See further, on Lithophysce, page 337. II. LIFE: ITS MECHANICAL WORK AND ROCK CONTRIBUTIONS. The making of rocks out of organic contributions, and the protective, transporting, and destructive effects of life, are the subjects here under consideration. GENERAL REMARKS ON ROCK-MAKING. 1. Materials Afforded by Plants and Animals. The organic contributions to rock-making are mentioned on page 71. It appears that PLANTS afford Calcareous material for rocks : mainly through Nullipores and Coccoliths, and other calcareous Algae or the lowest of Cryptogams. Siliceous material : through Diatoms, and some confervoid Algae ; and spar- ingly through other plants, the ashes of which afford some silica and alumina. Carbonaceous materials : through plants of all kinds, but especially those that flourish in wet soils and marshes, where means of burial are convenient. ANIMALS afford Calcareous material : through Rhizopods among Protozoans ; Spongiozoans with calcareous spicules, to a very small extent ; Actinozoaiis, or the Corals ; Hydrozoans of the Hydroid section; the lower Echinoderms or the Crinoids and Cystoids, and other Echinoderms sparingly; Molluscoids, as the Brachio- LIFE : ITS MECHANICAL WORK AND ROCK CONTRIBUTIONS. 141 pods and Bryozoans ; Mollusks of all the divisions ; Articulates, or Worms and Arthropods, very sparingly ; and sparingly, Fishes among Vertebrates, and very sparingly, other Vertebrates. Siliceous material: through Kadiolarians among Protozoans; and exten- sively, Spongiozoans having siliceous spicules or skeleton. Carbonaceous materials : sparingly through the decomposition of aquatic species and the dissemination of organic matters in bottom muds. Plwspliatic materials : chiefly through excrementitious matters ; sparingly from shells of some of the lower Brachiopods, and of Pteropods ; sparingly from tests of Trilobites, Crustaceans, and other Arthropods, and bones of Vertebrates ; and animal tissues. For analyses see page 72. 2. Relations of the Kinds of Life to Rock-making. The fitness of species for rock-making depends not only on the amount and character of their stony secretions, but also on their geographical distri- bution, and this on their relations, as regards growth, to temperature, light, moisture, and the composition and mechanical condition of the air, waters, or soil inhabited; the height over the land, the depth in the water, and all conditions affecting growth and burial. Marine species of plants and animals are those most likely to become fossils, and so to contribute to rock-formations ; and, among terrestrial spe- cies, those that live in lakes or marshes, or along their shores or borders. The reasons are two : (1) Because almost all fossiliferous rocks are of marine origin ; and (2) because organisms buried under water, or in wet deposits, are preserved from that complete decomposition to which many are liable when exposed on the dry soil, and are also protected from other sources of destruction. Over the land, the chance of burial is very small. Plants and all animal matter pass off in gases, when exposed in the atmosphere or in dry earth ; and bones and shells become slowly removed in solution, when buried in sands through which waters may percolate. Vertebrate animals, as Fishes, Eeptiles, etc., which fall to pieces when the animal portion is removed, require speedy burial after death, to escape destruction from this source as well as from animals that would prey upon them. Among Insects the species that frequent marshy regions, and especially those whose larves live in the water, are the most common fossils, as the Neuropters ; while Spiders, and the Insects that live about the flowers of the land, are of rare occurrence. Waders, among Birds, are more likely to become buried and preserved, than those which frequent dry forests. But, whatever their habits, Birds are among the rarest of fossils, because they usually die on the land, are sought for as food by numberless other spe- cies, and have slender hollow bones that are easily destroyed. Mastodons have been mired in marshes, and thus have been preserved to the present time; while the thousands that died over the dry plains and hills have left no relics. 142 DYNAMICAL GEOLOGY. The animals generally of the ocean are little liable to extermination from changes of climate over the land ; and hence some marine invertebrate species of the early Tertiary, many of the later, and all of the Quaternary, have continued on until now, while, as regards terrestrial animal life, there were in this interval many successive faunas. The lowest species of life' are the best rock-makers; namely, Corals, Cri- noids, RhizopodSj Diatoms, Millepores, Bryozoans, Brachiopods, Mollusks ; for the reason that the structures of only the simplest kinds can consist mostly of stone and still perform all their functions. Multiplication of bulk for bulk is more rapid with the minute and simple species than with the higher kinds ; for all animals grow principally by the multiplication of cells; and when single cells or minute groups of them, as in the Rhizopods, are independent animals, the increase may still be the same in rate per cubic foot, or even much more rapid, on account of the simplicity of structure. While, therefore, we may conclude that we have, in known fossils, a fair though incomplete representation of the marine life of the globe, we know very little of its terrestrial life, enough to assure us of its general course of progress, but not enough for any estimate of the number of living species over the land ; or for safe deductions as to lines of succession. Geology may have within reach of study fossils representing a twentieth of its marine life ; but it has not more than a thousandth of its terres- trial life. Some examples of marine accumulation. (1) Beds of oysters, along with other living species, exist in the shallow seas, as off the coast of North America, but in waters too deep for disturbance by the waves. Sands or earth encroach upon them through the marine currents, but not to the destruction of the species. Afterward, through some geological change, beds of detritus are washed over them, exterminating the oysters and perhaps other species also. This is one case ; and in it the fossils are unbroken. (2) In another place, the relics of the life of the coast, the shells, Corals, Crustaceans, etc., live so near the sea level as to be within reach of the waves, and hence they may be dislodged at times of heavy storms, and may become ground into fragments and sand ; or they may be contributed to under-water banks, and some of the shells may be scarcely worn, and therefore good fossils. (3) In another case, the worn fragments, coarse and fine, may be washed up a beach and ground fine or coarse by wave action. (4) Again, the species may live over seashore flats which are so shallow that the triturating waves act gently, and all relics thereby become ground to mud, and not one is left to make a distinguishable fossil. (5) Again, where barriers off a seacoast exclude the salt water with its marine life, not a sea-relic of any kind may be put into the accumulating seashore beds until some change of conditions removes the barrier. 3. Methods of Fossilization. In the simplest kind of fossilization there is merely a burial of the relic in earth or accumulating detritus, where it undergoes no change. Examples LIFE: ITS MECHANICAL WORK AND BOCK CONTRIBUTIONS. 143 of this kind are not common. Siliceous Diatoms and flint implements are among them. In general, there is a change of some kind; usually, either a loss, by decomposition, of the less enduring part of the organic relic, with sometimes the forming of new products in the course of the decomposition, or an altera- tion, through chemical means, changing the texture of the fossil, or petrify- ing it, as in the turning of wood into stone. The change may consist in a fading or blanching of the original colors ; in a partial or complete loss of the decomposable animal portion of the bone or shell, a process that leaves shells and bones fragile. It may be a loss of part of the mineral ingredients by solvent waters, as of the phosphates and fluorides of a bone or shell ; or a general alteration of the original organism, leaving behind only one or two ingredients of the whole ; or a combin- ing of the old elements into new compounds, as when a plant decays and changes to coal or one or more carbohydrogens, a resin to amber, animal matter to adipocere. It may be merely one of crystallization. The change often consists in the reception of new mineral matter into the pores or cellules of the fossil, as when bones are penetrated by limestone or oxide of iron. Through this method bones may become as firm as when living, though also much heavier. The change is frequently a true petrifaction, in which there is a substitution of new mineral material for the original ; as when a shell, coral, or wood is changed to a siliceous fossil, through a process in which the organism was subjected to the action of waters con- taining silica in solution. In other cases, the organism becomes changed to calcium car- bonate, as in much petrified wood ; and in others, to oxide of iron, or to pyrite ; and more rarely to fluor spar, barite, or apatite. The mineral matter first fills the cells of the wood, and then takes the place of each particle as it decomposes and passes away, until finally the original material is all gone. Some fossil logs are carbonized at one end and silicified at the other. The silica in most siliceous petrifactions has come from siliceous organisms, such as species of Sponges, or shells of Diatoms, from living species of the period that were associated with the fossil in the original deposit. EXAMPLES OF THE FORMATION OF STRATA THROUGH THE AGENCY OF LIFE. 1. Deposits from Pelagic and Abyssal Life. 1. Plants. Ordinary seaweeds, although in general littoral species, float widely over the ocean in some seas, as in the case of the Sargasso Sea of the north Atlantic. Moreover, the shore seaweeds are often drifted off by the currents. But the supply, while of importance as food for the animal species of the sea-bottom, makes no abyssal vegetable deposits. Dredging has brought up no remains of such deposits. But Diatoms, which becloud the waters of the southern ocean, and there serve for the vegetable food of Whales, make the great deposits of Diatom ooze, as already described, besides giving a sprinkling of siliceous shells over all other parts of the ocean's bottom. These shells, as stated by Murray, are especially noticeable in the deeper Ked ooze, because the carbonic acid, which removes calcareous relics, leaves them uninjured. 144 DYNAMICAL GEOLOGY. 2. Animals. Radiolarians or Rhizopods, having siliceous shells, make Radiolarian ooze in the deeper parts of the ocean. Sponges contribute much silica in the shape of spicules and skeletons to deposits from shallow depths to the lowest. Globigerinse with other Rhizopods make Globigerina ooze, especially between depths of 1500 and 2900 fathoms, but not in the higher latitudes. Pteropods are a characteristic of other bottom deposits between 500 and 1400 fathoms. But besides these characteristic species there are also the solitary Corals, the Echinoderms, Mollusks, and various other abyssal species, giving variety to the fossils of the sea-bottom. There are also at the bottom the relics of the great variety of pelagic species which after death escape feeders and sink to the bottom. Murray says that, in the course of the Challenger cruise, over 600 Sharks' teeth (genera Carcharodon, Oxyrliina, and Lamna) and 100 ear-bones of Whales (genera Ziphias, Balcenoptera, Balcena, Oca, and Del- phinus), along with 50 fragments of other bones, were obtained in one haul of the dredge in the central Pacific. The locality was, however, not in either of the organic oozes mentioned, but in the " Red ooze " ; and the phosphatic nature of bone was its protection from carbonic acid. Along the course of the Gulf Stream and of its abundant life, the bottom deposit is largely earthy or " terrigenous," and sometimes contains stones of considera- ble size which were distributed by the floating ice of the Glacial period. The blue and gray muds of the sea-bottom, which are common in the Pacific, are due to the volcanic dust, cinders, and pumice with which it has been sprinkled by the ocean's aerial volcanoes, and to their decomposition ; and Phillipsite (page 136) is found chiefly in the areas of the Red ooze. 2. Deposits from Littoral Species. The process of limestone-making by shells and corals is essentially the same in its more important steps, and therefore only the latter is here considered. CORAL FORMATIONS. Coral formations are made from the calcareous secretions of coral-making polyps, with large contributions from the shells and other relics of the littoral fauna. Coral formations, while of one general mode of origin, are of two kinds : 1. Coral islands. Isolated coral formations in the open sea. 2. Coral reefs. Banks of coral, bordering other lands or islands. The positions of the coral-reef seas and the causes of limitation are explained on pages 46, 56, and illustrated on the chart, page 47. The exclusion of corals from certain tropical coasts is owing to different causes : (1) Cold extratropical oceanic currents, as in the case of western South America (see chart). (2) Muddy or alluvial shores, or the emptying of large rivers ; for coral-polyps require clear sea water and generally a solid LIFE : ITS MECHANICAL WORK AND ROCK CONTRIBUTIONS. 145 foundation to build upon. (3) The presence of volcanic action, which, through occasional submarine action, destroys the life of a coast. (4) The depth of water on precipitous shores ; for the reef-making corals do not grow where the depth exceeds 150 feet. For the last-mentioned reason, reefs are prevented from commencing to form in the deep ocean. But if by other accumulations, or in any other way, the bottom is brought up to the limiting distance from the surface, Corals may commence the making of reefs. Coral formations are most abundant in the tropical Pacific, where there are 290 coral islands, besides extensive reefs around other islands. The Paumotu Archipelago, east of Tahiti, contains between 70 and 80 coral islands ; the Carolines, including the Radack, Ralick, and Gilbert groups, as many more ; and others are distributed over the interme- diate region. The Tahitian, Samoan, and Fiji Islands are famous for their reefs ; also New Caledonia and the islands to the northwest. There are reefs also about some of the Hawaiian Islands. The Laccadives and Maldives, in the Indian Ocean, are among the largest coral islands in the world. The East Indies, the eastern coast of Africa, the West Indies, and southern Florida abound in reefs ; and Bermuda, in latitude 32 N. , is a coral group. Reef-forming Corals are absent from western America, except along the coast of Central America as far north as the Gulf of California, and they are mostly absent from western Africa, on account of the cold extratropical currents that flow toward the equator : for the same reason, there are no reefs on the coast of China. (See the Physiographic Chart.) 1. Coral Islands. 1. Forms. Atolls. A coral island commonly consists of a narrow rim of reef, surrounding a lagoon, as illustrated in the annexed sketch (Fig. 143). 143. Coral island, or atoll. Such islands are called atolls, a name of Maldive origin. Maps of two atolls are given in Figs. 144, 145, showing the rim of coral reef, the salt- water lake or lagoon, and the variations of form. They are never circular. 144. 145. ATOLLS. Fig. 144, Apia, one of the Gilbert Islands ; 145, Menchikoff, one of the Carolines. The size varies from a length of fifty miles to two or three ; and, when quite small, the lagoon is wanting, or is represented only by a dry depression. DANA'S MANUAL 10 146 DYNAMICAL GEOLOGY. The reef is usually to a large extent bare coral rock, swept by the wares at high tide. In some reefs the dry land is confined to a few isolated points, as in Fig. 145 ; in others, one side is wooded continuously, or nearly so, while the other is mostly bare, as in Fig. 144. The higher or wooded side is that to the windward, unless it happens to be under the lee of another island. On the leeward side, channels often open through to the lagoon (e, Fig. 144), which, when deep enough for shipping, make the atoll a harbor ; and some of these coral-girt harbors in midocean are large enough to hold all the fleets of the world. Fig. 146 represents a section of an island, from the ocean (o) to the lagoon (I). On the ocean side, from o to a, there is shallow water for some distance out (it may be a quarter or half a mile or more) ; and, where not too deep (not over 150 feet), the bottom is covered here and there with growing corals. Between a and b there is a platform of coral rock, mostly bare at low tide, but covered at high, having a width usually of about a 146. Section of a coral island, from the ocean (o) to the lagoon (I). hundred yards : there are shallow pools in many parts of it, abounding in living corals and other kinds of tropical life : toward the outer margin, it is quite cavernous ; and the h.oles are frequented by Crabs, Fishes, etc. At b is the white beach, six or eight feet high, made of coral sand or pebbles and worn shells : b to d is the wooded portion of the island. The whole width, from the beach (b) to the lagoon (c), is commonly not over 300 or 400 yards. At c is the beach on the lagoon side, and the commencement of the lagoon. Corals grow over portions of the lagoon, although, in general, a large part of the bottom, both of the lagoon and of the sea outside, is of coral sand. Beyond a depth of 150 feet there are no growing corals, except some kinds that enter but sparingly into the structure of reefs. 2. Coral-reef rock. The rock forming the coral platform and other parts of the solid reef is a white limestone, made out of corals and shells. In some parts it contains imbedded corals ; in others, it is as compact as any Silurian limestone and without a fossil of any kind, unless an occasional shell. The compact non-fossiliferous kinds are formed in the lagoons or sheltered channels ; the kinds made of broken corals, on the seashore side, in the face of the waves ; those made of corals standing as they grew, in sheltered waters, where the sea has free access. Large portions are a coral and shell conglomerate. 3. Coral beach-rock. The beach-rock is made from the loose coral sands of the shores, which are thrown up by the waves and winds. The sands become LIFE : ITS MECHANICAL WORK AND ROCK CONTRIBUTIONS. 147 cemented into a porous calcareous sandstone, or, where pebbly, into a coral pudding-stone. It forms layers, or a laminated bed, along the beach of the lagoon, and also on the seashore side, sloping generally at an angle of five to eight degrees toward the water, but sometimes at a larger angle, this depending on the slope of the beach at the place. The rock is sometimes an oolyte, owing to the coating of the grains with the calcareous cement as solidification goes on. Oolyte is especially common where accumulations of sand make large sand-flats partly emerged at low tide. 4. Formation of the coral reef. A reef -region is a plantation of living corals, in which various species are growing together in crowded thickets, or in scattered clumps, over fields of coral sand. Besides corals and shells, there are also calcareous plants, called Nullipores, growing over the edge of the reef, in the face of the breakers, as shown by Darwin, and attaining considerable thickness. Even the delicate branching kinds sometimes make thick beds, as observed by Agassiz in the Florida seas. Bryozoans add a little to the material, occasionally making large massive corals. In Paleozoic time, both branching and massive kinds contributed largely to limestone formations. 5. Action of the waves. The waves, especially in t]ieir heavier move- ments, sweeping over the coral plantations, may be as destructive as winds over forests. They tear up the corals, and, by incessant trituration, reduce the fragments to a great extent to sand ; and the debris thus made and ever making is scattered over the bottom, or piled upon the coast by the tide, or swept over the lower parts of the reef into the lagoon, or drifted off by the currents for deposition elsewhere. The corals keep growing ; and this sand and the fragments go on accumulating: the consolidation of the material thus accumulated makes the ordinary reef-rock. Thus, by the help of the waves, a solid reef-structure is formed from the sparsely growing corals. Where the corals are protected from the waves, they grow up bodily to the surface, and make a weak, open structure, instead of the solid reef-rock ; or, if it be a closely branching species, so as to be firm, it still wants the compactness of the reef that has been formed amid the waves. 6. History of the emerging atoll. The growing corals and the accumulat- ing debris reach, at last, low-tide level. The waves continue to pile up on the reef the sand and pebbles and broken masses of coral, some of the masses even 200 or 300 cubic feet in size, and a field of rough rocks begins to appear above the waves ; and finally a beach is completed. The sands, now mostly above the salt water, are planted by the waves with seeds; trailing shrubs spring up; and afterward, as the soil deepens, palms and other trees rise into forests, and so the finished atoll receives its foliage. The windward side of such islands is the highest, because here the winds and waves act most powerfully. But where the leeward side of one part of the year is the windward of another, the two may not differ much. The water that is driven by the winds or tides over the reef, into the lagoon, 148 DYNAMICAL GEOLOGY. tends by its escape to keep one or more passages open, which, when suffi- ciently deep, make entrances for shipping. 2. Coral Reefs. The coral reefs around other lands or islands rest on the bottom along the shores. They are either fringing or barrier reefs, according to their position. Fringing reefs are attached directly to the shore, while barrier reefs, like artificial moles, are separated from the shore by a channel of water. The island represented in Fig. 147 has a fringing reef (/), and a barrier reef (6) with an intervening channel. To the right of the middle the reef is wanting, because of the depth of water ; and, farther to the right, there is only a fringing reef. Fig. 149 is a map of an island with a fringing reef; and Figs. 150-152, others, with barrier reefs. At two points through the barrier reef, in Fig. 147, there are openings to harbors (7i). The chan- nels from harbor to harbor around an island are sometimes deep enough View of a high island with barrier and fringing reefs. for ship navigation, and occasionally, as off eastern Australia, fifty or sixty miles wide ; but they are generally too shallow for boats. The barrier some- times becomes wooded for long distances, like the reef of an atoll; but commonly the wooded portion, if any exists, is confined to a few islets. Barrier and fringing reefs are formed like atoll reefs ; and special explana- tions are needless. The reefs adjoining lands have sometimes great width. On the north side of the Fijis, the reef -grounds are five to fifteen miles in width. In New Caledonia, they extend 150 miles north of the island, and 50 south, making a total length of 400 miles. Along northeastern Australia, they stretch on, although with many interruptions, for 1000 miles, and often at a distance, as just stated, of 50 or 60 miles from the coast, with a depth of 300 or 360 feet between. But the reefs, as they appear at the surface, even over the widest reef-grounds, are in patches, seldom over a mile or two broad. The patches of a single reef-ground are, however, connected below by coral rock, which is struck, in sounding, at a depth usually of 10 to 40 or 50 feet. The transition in the inner channels, from a bottom of coral detritus to one of common mud or earth derived from the hills of the encircled island, is often very abrupt. Streams from the land bring in this mud, and distribute it according to their courses through the channels. LIFE: ITS MECHANICAL WORK AND ROCK CONTRIBUTIONS. 149 3. Origin of the Forms of Reefs, the Atoll and the Distant Barrier. The origin of the atoll form of reefs was first explained by Darwin. According to his theory, each atoll began as a fringing reef, around an ordinary island ; and the slow sinking of the island till it disappeared, while the reef continued to grow upward, left the reef at the surface, a ring of coral around a lake. As reef-forming corals grow only within depths not greater than 150 feet, the bottom on which they began must have been no deeper than this ; and as such a shallow depth is to be found, with rare exceptions, only along the shores of lands or islands, the reef formed would be at first nothing but a fringing reef. A fringing reef, the first step in coral formations, being begun, slow subsidence would make it a barrier reef. In the lower part of Fig. 148, a section of a high island, ATPB, is repre- sented. The horizontal line 1 is the level of the sea, / a section of the fringing reef on the left, and /' of that on the right. The reef depends for its upward progress on the growth of the coral, and on the waves. The waves act only on the outer margin of a reef, while the dirt and fresh water 148. 3._ Section of an island bordered by a coral reef, to illustrate the effects of a subsidence. of the land directly retard the inner part. Hence the outer portion increases most rapidly, and retains itself at the surface, during a slow subsidence that would submerge the inner portion. The first step, therefore, in such a sub- sidence, is to change a fringing reef into a barrier reef (or one with a channel of water separating it from the shore). Continued subsidence widens and deepens this channel. Then, as the island begins to disappear, the channel becomes a lake, with a few peaks above its surface ; and later, a single peak of the old land is all that is left. Finally this peak' disappears, and the coral reef comes forth an atoll, with its lagoon complete. Referring again to the figure : if, in the subsidence, the horizontal line 2 becomes the sea level, the former fringing reef / is then at b, a barrier reef, and /' is at b 1 , and ch, ch', ch" are sections of parts of the broad channel or area of water within ; over one of the peaks, P, of the sinking island, there is an islet of coral, i ; when the subsidence has made the horizontal line 3 the sea level, the former land has wholly disappeared, leaving the barrier 150 DYNAMICAL GEOLOGY. reef, t, t 1 , alone at the surface, around a lagoon, III, with an islet, u, over the peak T, which was the last point to disappear. These steps are well illustrated at the Fijis. The .island Goro (Fig. 149) has a fringing reef; Angau (Fig. 150), a barrier; Exploring Isles (Fig. 151), a very distant barrier, with a few islets; Numuku (Fig. 152), a lake with a single rock. The disappearance of this last rock would make the island a true atoll. Whenever the subsidence ceases, the waves build up the land above the reach of the tides ; seeds take root ; and the reef becomes covered with foliage. 149-152. The lands inside of coral barriers, as illustrated in these figures, very often show, by their narrow broken features and the deep indentations that were once valleys, that they are sunken lands, and thus sus- tain Darwin's theory. The atoll Menchikoff (Fig. 145) was islands of the Fiji group: Fig. 149, Goro; evidently formed, as explained by Darwin, mu'ku ngaU: m> Exploringl8les; 152)Nu - about a high island, consisting of two dis- tinct ridges or clusters of summits, like Maui and Oahu in the Hawaiian group. If the subsidence be still continued, after the formation of the atoll, the coral island will gradually diminish its diameter, until finally it may be reduced to a mere sand-bank, or become submerged in the depths of the ocean. The occurrence of sunken atolls, like the Maldives, is one of the strong arguments for the theory of subsidence. Thickness of reefs. The thickness of a coral formation, supposing Dar- win's theory to be the true one, is often very great. From soundings within a short distance of coral islands, it is certain that this thickness is in some cases thousands of feet. The barrier reefs remote from an island stand in deep water, approximately proportional in depth to the distance from the coast-line. Supposing the slope of the bottom at the Gambier Islands to be only five degrees, we find, by a simple calculation, that the reef has a thick- ness of 1200 feet. In a similar manner, it is found that the thickness must be at least 250 feet at Tahiti, and 2000 or 3000 at the Fijis. The rate of subsidence required to produce the results described cannot exceed the rate of upward increase of the reef-ground. On page 385 some facts are given illustrat- ing the exceeding slowness of such movements. 1 As coral debris is distributed, by the waves and currents, according to the same laws that govern the deposition of silt on sea coasts, it does not necessarily follow that the 1 For further information on the subject of Coral reefs and limestones, the reader may refer to the author's work on Corals and Coral Islands, 400 pp. 8vo., 1891, based on his Exploring Expedition Report on Zoophytes (740 pp. 4to, and 61 plates in folio, 1846), and to the chapter on Coral Reefs and Islands in his Expedition Report on Geology (750 pp. 4to, with 21 plates in folio, 1849) ; also to Darwin on the Structure and Distribution of Coral Reefs, 8vo, with maps and illustrations, London, 1842, the last edition, by Professor T. G. Bonney, in 1889. LIFE: ITS MECHANICAL WORK AND ROCK CONTRIBUTIONS. 151 existence of a reef in the form of a barrier is evidence of subsidence in that region. On page 224 the existence of sand barriers of similar position is shown to be a common feature of coasts like that of eastern North America. In the cases of the barriers about the islands of the Pacific, however, there is no question on this point. Such barriers do not form about islands so small. Moreover, the great distances of the reefs from the shores, in many cases, and the existence of islands representing all the steps between that with a fringing reef and the true atoll, leave no room for doubt. The remoteness of the Australian barrier from the continent, and the great depth of water in the wide channel, show that this reef is unquestionable proof of a subsidence, though it is not easy to determine the amount. Along the shores of continents, the question whether a barrier coral reef is evi- dence of subsidence or not must be decided by the facts connected with each special case. In opposition to Darwin's theory of subsidence it is held by some writers that the sea- bottom may have been brought up toward the ocean's surface by deposits of other lime- secreting species, as those of the shells of Rhizopods, until they were near enough to become next a plantation of corals, and that, in this way, without any subsidence, atolls became common within the area of the tropical oceans. But the wide oceans are wonder- fully free from such banks ; and if they were used, the growing reef made over the sub- merged basement would fail of its deep lagoons. Excavation of lagoon basins has been attributed, by the opposing theorist, to the eroding action of the carbonic acid in sea water, carried by currents over the bank and through depressions that ware likely to form about the center of the bank. But many large lagoons have no entrance, and gen- erally there is only a shallow entrance ; and currents have no power below the level of the entrance (or exit). J. Murray has proposed the theory that since the fringing reef widens outward by growth and wave-action, this process may be the sole cause of the width of reefs along shores. Against the opposing theories there are the positive facts, that elevated coral reefs and atolls exist, which have a thickness beyond 150 feet. Among the many facts there are the following : Metia, an elevated atoll, north of Tahiti, has a height of 250 feet, which is twice the depth of growing reef corals ; Christmas Island, in the Indian Ocean, 1200 feet in height, has an exterior of coral-made terraces to its summit. For a full discussion of this subject reference may be made to the author's work mentioned in the note to the preceding page. The following are the teachings of the coral reefs : 1. Beds of coral limestone and shell limestone are made (1) by accumu- lation through growth ; 2) by the mechanical action of waves and marine currents ; (3) by consolidation taking place as the work goes forward. 2. Limestones of the purest kind on a scale of great magnitude form in the littoral zone within seas not over 150 feet deep. The modern reefs in the midst of the ocean are narrow and have broad channels ; but over a conti- nental sea, the same methods would produce solid limestone formations of unsurpassed extent, fossiliferous or unfossiliferous, and also beach sand-rocks, conglomerates, andoolytes; and with the aid of the winds, wind-drift rocks of coral sand. 3. Great limestones are therefore not necessarily, or generally, of deep- water origin. 4. Limestones attain great thickness at the present time by means of a slow subsidence, as they have in all geological time. 5. Further : comparing littoral with abyssal conditions, we learn that the former make stratified deposits containing or consisting of remains of litto- ral life ; the latter make unstratified deposits containing or consisting of 152 DYNAMICAL GEOLOGY. pelagic life. (See further, page 143.) The stratified limestones and other rocks of North America have no true deep-water characteristics. Wyville Thomson gave this as his general conclusion for all continents. 3. Deposits made by Continental Species. 1. SILICEOUS DEPOSITS. Conferva-like Algse, having columnar, vase-shaped and furze-like forms, grow in the hot geyser waters of the Yellowstone Park, which secrete opal- silica freely throughout the plant, as first reported by W. H. Weed. They cause the deposition of the silica from the waters in a gelatinous form, making the geyserite basins and the wide-spread geyserite deposits. These siliceous plants are described as growing an inch upward in 10 weeks. Diatoms make beds in shallow ponds over the continents, and thick deposits of them are common beneath the peat of ordinary marshes. Such ponds have only the gentlest of waves ; but sufficient to break into pieces most of the infinitesimal shells. Diatoms are especially abundant in the warm waters of the Yellowstone Park, where the beds made from them cover many square miles in the vicinity of active and extinct hot springs, and vary from three to six feet in depth. Near Monterey, Cal., there is a Diatom bed 50 feet thick. Others occur in Nevada, where, according to Ring, they alternate with beds of tufa ; and some are 200 or 300 feet thick. The material of the beds looks like chalk, but it often becomes partially solidified to opal, of a brown, yellowish, or greenish color. 2. CALCAREOUS DEPOSITS. 1. The shells of terrestrial and freshwater Mollusks are mostly thin and fragile, especially the Gastropods, breaking easily under the gentlest wave action. Limestones with unbroken shells as fossils are of rare occurrence and small extent, forming only in bodies of water too shallow for wind- waves. The more common genera are Splio&rium, Limncea, Physa, Planorbis, Paludina, and Pupa. The deposits over the bottoms of small ponds are usually accumulations -of pulverized shells, and have a chalky aspect. The earthy and clayey beds of river valleys ordinarily contain nothing of the shells of the valley except minute grains from their wear, or calcareous concretions made from the grains. The fine earthy loess of large valleys is remarkable for the number of its freshwater shells (Gastropods), its strongly calcareous character, and its calcareous concretions, and bears evidence thus of the sublacustrine and shallow conditions attending its deposition. 2. Loosely textured calcareous rock, called tufa because of its appearance, is formed from the confervoid Algse of the Yellowstone Park and other regions. It is an aggregation of the algoid growths, some of which resemble somewhat the concretionary forms represented in Fig. 137 on page 132. LIFE : ITS MECHANICAL WOKK AND KOCK CONTRIBUTIONS. 153 Dr. A. Rothpletz has stated that, according to his observations at Great Salt Lake, Utah, the concretionary grains of oolyte are due to the growth and calcareous secretion of a minute Alga or water-plant (1893); and that they are formed there within a bluish green alga-mass. He is disposed to account thus for the formation of ordinary oolyte. Oolyte is an abundant product along the low coral-sand shores of southern Florida, and its formation has been attributed to deposition from the sea water around minute grains of the sand, or around some still more minute shell of a Diatom or other microscopic organism. 3. PHOSPHATIC DEPOSITS. Guano beds are the important deposits of phosphatic material. The origin and constitution of guano are described on page 72. The composition is approximately : organic and volatile matter 40 per cent, phosphoric acid 14, lime 12, potash and soda 7, nitrogen 9, along with water. The agricul- tural value is largely owing to the nitrogen. Besides the kinds mentioned, Bat guano is formed in some caves ; and in Victoria, southern Australia, it has a depth of 30 feet in the Skipton caves. The prominent localities of guano are : islands on the nearly rainless Peruvian coast, which were worked as early as the sixteenth century ; various islands of the equatorial Pacific, between 155 W. and 277 W. ; Sombrero and neighboring islands in the West Indies, and also large coastal areas in South Carolina and Florida. In the West Indies, and in South Carolina and Florida, where the rains are common, the guano is mostly destitute of nitrogen, it being the impure calcium phosphate made by the filtration of rain-waters through the original guano, carrying the soluble phosphates into underlying calcareous deposits. Fossil shells and bones are among the phosphatized products. 4. Peat and other Carbonaceous Formations. Peat is an accumulation of half-decomposed vegetable matter, in wet or swampy places over the interior of a continent or about its estuaries. In temperate climates, it is due to the growth mainly of spongy Mosses, of the genus Sphagnum, which are very absorbent of water. Beside spreading over 153. Peat-forming in progress, with a Diatom deposit (d) over the bottom of the pond. Shaler. the swampy surfaces, they extend out a floating layer from the borders of shallow ponds (6), as illustrated in Fig. 153, from Shaler's Memoir on the Origin and Nature of Soils. The floating layer (6, 6) drops portions to the 154 DYNAMICAL GEOLOGY. bottom from its lower dying surface; for the moss has the property of dying at the extremities of the roots as it grows above. It thus gradually takes possession of the pond, and may form beds of great thickness. In some limestone regions, the Sphagnous mosses are replaced by species of Hypnum, as in Iowa. The leaves and stems, branches and stumps, of trees and shrubs, growing over the marshy region or in shallow waters, and any other vegetation present, contribute to the accumulating bed. The fresh- water shells growing in the waters, and the spicules of any sponges, with the insects, and the carcasses and excrements of animals become included. Earthy material also may be blown over the marsh by the winds, or brought by inflowing streams. In wet parts of Alpine regions, there are various flowering plants which grow in the form of a close turf, and give rise to beds of peat, like the moss. In Fuegia, although not south of the parallel of 56, there are large marshes of such Alpine plants, the mean temperature being about 40 F. On the Chatham Islands, 380 miles east of New Zealand, peat thus formed has a depth of 50 feet. The dead and wet vegetable mass slowly undergoes a change in its lower part, becoming brownish black, loose in texture, and often friable, although commonly penetrated with rootlets. The change is sometimes continued until coal is formed ; but unlike good coal it still contains usually 25 to 33 per cent of oxygen. Peat-beds cover large surfaces of some countries, and occasionally have a thickness of 40 or 50 feet. The rate of growth varies with the amount of vegetation, moisture, and other conditions ; a foot in depth may form in five to ten years. One tenth of Ireland is covered by them ; and one of the "mosses" of the Shannon is stated to be 50 miles long and two or three broad. A marsh near the mouth of the Loire is described by Blavier as more than 50 leagues in circumference. Over many parts of New England and other portions of North America, there are extensive beds, almost every old marsh having more or less peat below. The amount in Massachusetts alone has been estimated to exceed 120,000,000 of cords. The Dismal Swamp, 10 miles by 30 in area, situated on the borders of Virginia and North Caro- lina, is for the most part a region of very deep peat. Peat-beds sometimes contain standing trees, and entire skeletons of ani- mals that had sunk in the swamp. The peat-waters have an antiseptic power, and consequently tend to prevent complete decay of the vegeta- ble matter of the peat-bed. Flesh is sometimes changed by the burial into adipocere. Peat is used for fuel, and also as a fertilizer. When prepared for burning, it is cut into large blocks, and dried in the sun. It is sometimes pressed, in order to serve as fuel for steam-engines. Muck is another name for peat, especially for impure kinds, when em- ployed as a manure ; any black swamp-earth consisting largely of decomposed vegetable matter is so called. Beds of marine plants in the rocks of littoral regions are almost unknown.. Specimens LIFE: ITS MECHANICAL WORK AND ROCK CONTRIBUTIONS. 155 are distributed through the formations, and have been the source of some coaly products ; but never abundantly. The trunks of Lessonia, as large as a man's thigh, lie piled in great quantities on the shores of the Falkland Islands. Moreover, the growth of sea-weeds is very rapid. On the coast of Scotland, and below low-tide level, "a surface chiseled smooth in November, was thickly covered in the following May with ribbon kelp 2 feet long, and ordinary kelp 6 feet long." But no peat-like compact beds of marine Fucoids are known. Fucoids contain 74 to 80 per cent of water, some nitrogen, and are very muci- laginous ; and hence " when they begin a decay and become disorganized, they melt down into a very small bulk, and seem almost to dissolve away." (Storer.) The great interest to the geologist in this subject of peat-beds is the essen- tial identity between their method of origin and that of the great accumula- tions of vegetable debris out of which coal-beds were made. Both were accumulations of leaves and stems of terrestrial (not marine) plants, and occupy, as a general thing, the region where the plants to a large extent grew. The chemical processes of change were also essentially 'the same. The burial of the ancient beds beneath thick sediments in many successions, as explained on page 712, has made the chief differences. PROTECTIVE AND OTHER BENEFICIAL EFFECTS. The protective effects of life come chiefly from vegetation. 1. Turf protects earthy slopes from the wearing action of rills that would wear a bare surface into gullies ; and even hard rocks receive protection in the same way. 2. Tufts of grass and other plants over sand-hills, as on seashores, bind down the moving sands by their long creeping stems or spreading roots. 3. Lines of vegetation along the banks of streams prevent wear during freshets. When the vegetation consists of shrubs or trees, the stems and trunks entangle and detain detritus and floating wood, and serve to increase the height of the margin of the stream. 4. Vegetation on the borders of a pond or bay serves in a similar manner as a protection against the feebler wave-action. In many tropical regions, plants like the mangrove, growing at the water's edge, drop new roots from the branches into the shallow water. These roots act like a thicket of brush- wood, to retain the floating leaves, stems, and detritus ; and, as the water shal- lows, other roots are dropped farther out; and thus they keep marching outward, and subserve the double purpose of protecting and making land. The coarse salt-marsh grasses along seashores perform the same kinds of geological work, being very effectual agents in entangling detritus, and in protecting from erosion. 5. Patches of forest-trees, on the declivities in Alpine valleys, serve to turn the course of the descending avalanche, and entangle snows that, but for the presence of the trees, would only add to its extent. Such groves are usually guarded from destruction with great care. 6. Forests retard the melting of snow and ice in spring, and thus lessen the devastations of floods. 156 DYNAMICAL GEOLOGY. 7. Calcareous Algae, called Nullipores (page 147), serve to protect grow- ing Corals and the margins of coral reefs from wear. Ordinary seaweeds often cover and protect the rocks of a coast nearly to high-tide level ; in the higher latitudes the Fucoids (as Macrocystis pyrifera) are sometimes 200 to 300 yards long, and the broad green belt off a coast breaks the force of incoming waves so that the rocks are saved from their destructive action. The common earthworm, as Darwin has shown (1881), transfers a great amount of earth or soil in the pellets it discharges at the surface. He found that the weight so transferred per acre in a year in four cases was 7-56, 14-58, 16'1, and 18 '12 tons. Lobworms, of seashores, are even greater workers, according to C. Davison, who reports that the amount of sand carried up each year on the shores of Holy Island, Northumberland, was equivalent to 1911 tons per acre (1891). Marmots (Spermatophilus Eversmani), in the Caspian steppes, bring great quantities of earth to the surface. In a few years after their introduction they had brought up 75,000 cubic meters of earth to the square mile. (Muschketoff, 1887.) TRANSPORTING EFFECTS. 1. Seeds caught in the feathers, hair, or fur of animals, or contained in the mud adhering to their feet, are transported from place to place. 2. Seeds are eaten by animals as food, or in connection with their food, and are dropped in another region undigested. At the Solomon Islands, fruit- pigeons carry fruit and seeds in their crops, and have thus planted the land with trees from other islands. (Guppy.) 3. Ova of fish, reptiles, and inferior animals are supposed to be transferred from one region to another by birds and other animals. Authenticated instances of this are wanting. 4. Floating logs and seaweeds carry Mollusks, Crustaceans, Worms, and other species from one region to another, over the broadest oceans, along the courses of marine currents. In tropical countries, islands of shrubbery and trees often float away from estuaries into the sea, bearing with them land, fresh-water shells, and other terrestrial species, which there become mingled with marine shells. A Boa constrictor once floated, on the trunk of a cedar, from Trinidad off South America to the island of St. Vincent a distance of at least 200 miles. The great floating seaweed areas of the Sargasso Sea in the Atlantic are the dwelling-place of vast numbers of marine species, includ- ing Fishes, Mollusks, Crustaceans, Worms, etc. 5. Migrating tribes of men carry, in their grain, or otherwise, the seeds of various weeds, and also, involuntarily, Rats, Mice, Cockroaches, and smaller vermin. The origin of tribes may often be inferred from the species of plants and of domesticated and other animals found to have accompanied them. 1 1 On this general subject consult Wallace's Island Life. LIFE : ITS MECHANICAL WORK AND ROCK CONTRIBUTIONS. 157 DESTRUCTIVE EFFECTS. The destructive effects proceed either from living plants or animals, or from the products of decomposition. The latter subject is briefly considered under Chemical Work. 1. The roots which come from the sprouting of a seed in the crevice of a rock, as they increase in size, act like wedges, in tending to press the rock apart; and, when the roots are of large size, masses tons in weight may be 154. Rocks disrupted by roots of trees, between Gloucester and Rockport, Mass. Shaler, '89. torn asunder ; and if on the edge of a precipice, the detached blocks may be pushed off, to fall to its base. This is one of the most effective causes of the destruction of rocks. Many regions of massive and jointed rocks are thickly covered with huge blocks, looking like transported bowlders, which are the results of this kind of upturning. The Confervse and other simple plants often commence their wedging work in the smallest of rifts ; and yet by constant growth cause great results. Moreover, the opening of rifts and fissures gives access to moisture, and thus contributes further to rock destruction by chemical processes and by frost. 2. Boring animals, like the saxicavous Mollusks, make holes, often as large as the finger, and sometimes larger, in limestone and other rocks, along some seashores. Species of Saxicava, Pholas, Petricola, Lithodomus, Gastro- chcena, and even some Gastropods, Barnacles, Annelids, Echini, and Sponges, 158 DYNAMICAL GEOLOGY. have this power of boring into stone. Various species also bore into shells or corals. In seven years, Carrara marble, in the sea south of Long Island, became riddled with borings made by a Sponge, the Cliona sulphured, of Verrill. Termites, or White Ants, and many other insects, especially when in the larval state, the Limnoria among Crustaceans, and the Teredo, related to Pholas, among Mollusks, bore into wood ; and the last is so destructive to ships, piles, and wharves that it is often called the Shipworm or Pileworm. 3. The tunneling of the earth by small quadrupeds, as the Mole, and by Crustaceans like the Crawfish, sometimes results in the draining of ponds, and the consequent excavation of gullies or gorges by the out-flowing waters. The tunneling of the levees of the Mississippi by Crawfish is one cause of breaks, and thereby of great floods over the country. 4. Animals using Mollusks and Echinoderms as food make great refuse- heaps, or beds of broken shells. The animals include Man, as well as other species ; and the beds made by Fishes off the coast of Maine, as described by Verrill (who has drawn attention to this mode of making broken shells), are of great extent. They might be taken for beach deposits. The chief enemy of the American Oyster is a Starfish, which spreads its extensile mouth-opening over the young Oyster, and so gets it inside its stomach, and then, as the shell opens, digests the Oyster. 5. Fungi attack dead plants and animals, and rapidly destroy them. They do it by excreting ferments or poisons, which eat into and destroy the tissues. Living plants often suffer from this cause when in an enfeebled state. 6. The destruction of the vegetation of a region by insect life, and that of animals by one another, are also of great geological importance. III. THE ATMOSPHERE AS A MECHANICAL AGENT. The weight of 100 cubic inches of dry air, with the barometer at 30 inches, and the thermometer at 60 F., is 31 grains ; and hence it is but -^ as heavy as water (or -^ at 32 F.). The weight of a column of the atmosphere a square inch in area of section, when the barometric pressure is 30 inches, and the temperature 32 F., is 14-7 pounds. On this basis, the total weight of the atmosphere is about llf trillions of pounds (Herschel). In England, an atmosphere of pressure, used as a limit in connection with steam, is 29-905 inches Bar. at 32 F., or nearly 14| pounds to the square inch; in France, it is 760 millimeters, or 29-922 English inches, at the same temperature. The atmosphere, while rightly called the earth's aerial ocean, is an aerial ocean without a definite upper surface, resting on an ever-disturbing base- ment. It extends not only to a height of 40 miles, but, with increasing tenuity, to at least 200 miles, meteorites having become luminous at this height as a consequence of the friction of air. An upper limit is supposed to be determined by the equilibrium between the gravitation of the mole- cules of the elements constituting it and the expansive force, decreasing upward, that separates the molecules. THE ATMOSPHERE AS A MECHANICAL AGENT. 159 The basement on which it rests the earth's uneven surface varies widely in temperature, and this variation passes to extremes in the higher mountains, whatever the zone. The atmosphere's own temperature, even in the tropics, is at the freezing-point at a height of less than four miles. Through these and other conditions the atmosphere has its varying belts of greater and less depth, that is, of higher and lower barometric pres- sure, its areas of high and low pressure moving in great circuits, and, as a consequence, winds, storms, cyclones, tornadoes, in its fruitless effort toward a state of equilibrium. These winds are its chief means of mechani- cal work. The Mechanical Work of the Atmosphere. The atmosphere works mechan- ically (1) by denudation, or, as it has been termed, deflation, with or without abrasion ; (2) by transportation ; (3) by deposition ; and (4) through its pressure. The work and the results are called Eolian, from AioAos, the god of the winds. The force of the wind, measured by the pressure on a square foot, in- creases with the square of the velocity. At 5 miles an hour, the pressure is about 2 ounces to the square foot ; at 10 miles, which is that of a light breeze, 8 ounces ; at 20 miles, a good steady breeze, 2 pounds ; at 40 miles, a strong gale, 8 pounds ; at 60 miles, 18 pounds ; at 100 miles, 50 pounds. The work done is dependent largely on the form of the surface struck. This is well shown in the anemometer made of hemispherical cups : the difference between the pressure on the concave and convex sides being such that the cups move one third as fast as the wind, whereas with flat disks there would be no motion. A velocity of 186 miles an hour (or 170 pounds to the square foot) has been registered by the anemometer. While the lighter winds, and especially the great currents, like the trades, have a degree of regularity in movement, the storm winds, on which geo- logical work mainly depends, are hurrying bodies of air of inconstant force, breadth, and direction. A single storm includes all the courses of the com- pass, and all degrees of force, from lulls to extremest violence ; and when most constant, these winds are still made up of fitful blasts. Under such con- ditions, abrasion, transportation, and deposition should be greatly mixed; and this is a striking feature of the results. EOLIAN DENUDATION OK DEFLATION. Denudation, or wear by wind-force, is carried on (1) by simple wind-impact and (2) by impact when the air is loaded with sand or other material. 1. By simple impact. The lighter work of the winds is the taking up of dust from roads, sand-fields, sand-hills, and sea-beaches, to drift away to some other place. The streets of most cities and the roads of the country often afford examples of the work on dry, windy days. It is to be noted, however, that a rather strong wind is required for this light deflation unless moving wheels first stir up the dust. The result is due to the direct impulse 160 DYNAMICAL GEOLOGY. of the moving air ; and so it is when the hurricane tears up trees, prostrates forests, unroofs houses, or moves them from their foundations. These de- structive effects are dependent, as already explained, not merely on velocity, but also on the extent, form, and position of the object against which it strikes. The adhesion of the hardened mud along the ruts of a country road may not be overcome by a gale that prostrates forests. Besides lifting and transporting loose sands, the heavier winds tear off grains from exposed ledges or bluffs of rock, which the action of the sun, or oxidation, or saline efflorescences, or other means have loosened, and thus carry on the work of denudation. 2. By means of the material transported. But the sand, gravel, or stones borne by the winds give them their chief denuding power. Attention was first called to this wind work by W. P. Blake, who described the granite of the Pass of San Bernardino, Cal., as scratched like rocks of glacier regions, even quartz and tourmaline being finely polished, and the garnets left projecting on pedicels of feldspar, inclined in the direction of the wind ; limestone as eroded and channeled as if by dissolving waters. Mr. Blake observed, further, that the scratching and polishing effects were not confined to the Pass, but were visible over all parts of the Colorado desert to the eastward, where hard rocks were exposed ; and he dwells on the great impor- tance of this action of the winds as a means of denudation (1855). Later observers have shown that many of the bluffs, needles, and towers of soft sandstone characterizing the scenery in different parts of the Kocky Moun- tain region have been more or less shaped by this means. Moreover, scratches made by drifted sand, long since noticed on the glass of windows on Cape Cod, have been observed in Maine where it is not arid (G. H. Stone, 1886). In arid parts of India, according to Mr. R. D. Oldham, they differ from those of glaciers in being deepest at the end facing the wind. Eolian denudation has its best examples in the Egyptian and other true deserts where the annual fall of water is very small. The following fig- ures of Egyptian denuda- tion are from the work of J. Walther (1891), which treats the subject with great fullness and gives many illustrations, after personal observa- tions. The differences in hardness 'of the layers de- Southwest end of Mokkatam. Walther. termmes the rate of wear and leads to nearly the same forms that are produced by running water. In Fig. 155 the beds are Eocene limestone and other kinds. In Fig. 156 Cretaceous beds are upturned, and' the harder limestone caps each elevation. The deflation leaves silicified fossils (Exogyra and Corals) projecting over the surface, as in Fig. 156. THE ATMOSPHERE AS A MECHANICAL AGENT. 161 Other views in Mr. Walther's book represent deep excavations in nearly vertical bluffs, sometimes in regular alternation with narrow columns the latter the part which descending solutions of some kind (perhaps calcareous or ferruginous) had hardened; often they are very irregular in form. A blast of sand propelled by steam is now employed (after Nature's sug- gestion) in grinding and carving glass, gems, and 15 ^. even granite. Glass cov- ered by lace-work, or by paper having open pat- terns cut in it, is rapidly worn where its surface is exposed, while the lace or paper, owing to its yield- ing before the sand, shows scarcely any effect of the blast. Large cornices and mouldings of granite are shaped by a blast of steam and sand. Thoulet, of Paris, has investigated the effects of air-blast abrasion (1887) and found, besides other results, that moist rock abrades most easily, and that the effect is small if the surface struck has a dip of less than 60. Upturned Cretaceous beds near Abu Roasch. Walther. TRANSPORTATION AND DEPOSITION. The deep deposits of earth over ancient monuments in Eome and other old cities is largely a result of eolian transportation. The most extensive drift-sand deposits occur over arid areas where there is little or no vegetation to fasten down the sands, and where nearly all the year through the work is going on. But the best known are those of windward shores where fronted by long beaches. The sands of seabeaches often extend out long distances in the shallow waters. The breakers come in sand-laden, to throw the sand up the beach, and in ordinary weather the beach takes the whole. But storm-winds carry the sands from the breakers and the beach over the low surface beyond and pile it into ridges, often making a series of parallel sand- drifts. The sand keeps moving landward with each season of storms, unless stopped by steep declivities, or by vegetation whose encroachment is favored by moist soil ; and sometimes it drifts up the sea-border hills to heights of 100 to 200 feet. The surfaces of drifted sands are often covered with ripple-marks. The effects are greatest (1) where the sands are fine, and most purely siliceous and therefore incoherent ; (2) where the coasts are well open to the winds ; (3) in regions exposed to the most violent storms ; and (4) espe- cially on projecting points where the work is carried on in succession by the winds of both sides of a rotary storm, and by storms of different directions. Ordinary winds have little effect, and hence on the Pacific coral islands the DANA'S MANUAL 11 162 DYNAMICAL GEOLOGY. drift-hills of projecting capes are seldom over 30 feet high; while at the Bermudas and Bahamas, within the belt of Atlantic cyclones whose winds have often a velocity of 60 to 90 miles an hour, the sands cover great sur- faces, are sometimes quite coarse, and make ridges 100 to 230 feet in height. The highest drift ridges are on the side which receives the winds of the first half of the cyclone. On the south side of Long Island, drift-sand ridges extend along for a hun- dred miles and vary in height from 5 to 40 feet. The coast of New Jersey, down to the Chesapeake, and other coasts farther south, are similarly fronted by sand-hills. Similar hills occur also on the east side of Lake Michigan, where they reach a height of 100 to 200 feet; they are 215 feet high at Grand Haven, and 30 to 93 near New Buffalo. In Norfolk, England, between Hunstanton and Weybourne, they are 50 to 60 feet high. Such seashore driftings are a means of recovering lands from the sea. The sea first makes the sand-flats or beaches, and the winds do the rest. Lyell observes that, at Yarmouth, England, thousands of acres of land now under cultivation have been thus gained from a former estuary. The drift-sand also encroaches on fertile lands, forests, and villages. Such regions of encroaching sands are called dunes. On Lake Michigan, as Professor Winchell states, the sands are continually shifting with the winds; at Grand Haven and Sleeping Bear, the forest has become sub- merged, and " presents the singular spectacle of withered tree-tops pro- jecting a few feet above a waste of sands." The land at this place is extending lakeward, through the wear and contributions of the arenaceous shore rocks. Near Seven-mile Beach, on the New Jersey coast, in 1885, the dune, 40 feet high, had encroached on a dense forest to such an extent that "the tree-tops projected above its sands like the heads of drowning men above the waves." (F. J. H. Merrill, 1890.) By such means, not only bones, shells, tree-trunks, become the fossils of sand-heaps, but, in the existing age, as in Egypt, even monuments, temples, and cities. 1. Characteristics of wind-drift or eolian formations. The sands of wind- drifts, although deposited by blasts of wind, make thin and regular layers over the sand-fields and the surfaces of the rising ridges, producing a stratic- ulate structure about as coarse as that of common alluvial clays, parallel with the successive surfaces of the ridge. But such ridges are liable to be cut off on one side or the other by the most violent of gales ; and then deposition from the winds goes on over a new outer surface. By repetitions of such catastrophes, and continued depositions, the quaquaversal dip of the wind-drift structure, represented on page 93 (Fig. 63), is produced. The mode of formation and straticulate structure of sand-drifts is well illustrated in snow-drifts, which are a result of like wind-drift action. As snow drifts readily into heaps and ridges, wherever there is an obstacle however small, so it is with sand. Flat or level surfaces are the exception in such regions. The drift ridges of coral sand or shell sand readily consolidate, and show well the varying directions of the straticulation, as at the Bermudas, THE ATMOSPHERE AS A MECHANICAL AGENT. 163 Bahamas, Key West and elsewhere on the Florida Banks, and also on Oahu and other Hawaiian Islands. 2. Eolian transportation of volcanic ashes. The transportation of volcanic ashes usually takes place without drifting, and the bedding, therefore, is commonly horizontal. In 1812, ashes were carried from a volcano on St. Vincent to Barbados, 60 to 70 miles; and in 1835, from the volcano of Coseguina in Guatemala to Jamaica, a distance of 800 miles. In 1883, the dust from the volcano of Krakatoa, an island just west of Java, was thrown to a height of 50,000 feet, according to Verbeck, and continued to be pro- jected for 36 hours; and it is supposed that the ashes made the circuit of the globe, and were the cause of the sunset glows of the following autumn. The bottom of the Pacific has been found to be very generally covered with volcanic ashes derived from its many volcanoes. 3. Eolian transportation of living species or their relics. A tornado that becomes what is known as a " water-spout " over a large river or lake, carry- ing up at its center great quantities of water, will take up the ova and smaller life of the waters, and transfer them to other places, and may thus contribute new species to distant lakes or rivers. Land Birds and Insects are sometimes drifted far out to sea, and so reach oceanic islands, and some- times in the case of Birds another continent. Seeds of many kinds go with the winds. A Spider of the ballooning kind, Sarotes venatorius, has probably traveled around the globe, according to H. C. McCook, crossing oceans and continents, and thus has gained a world-wide distribution. A related species is reported by Darwin as suddenly appearing on the rigging of the " Beagle " 60 miles from the land. Showers of grayish and reddish dust sometimes fall on vessels in the Atlantic off the African coast, and over southern Europe (producing, when they come down with rains, "blood-rains"), the particles of which, as first shown by Ehrenberg, are largely microscopic organisms. The figures on the following page represent the species from a single shower, near Lyons, on October 17, 1846. The whole amount which fell was estimated by Ehrenberg at 720,000 pounds; and of this, one eighth, or 90,000 pounds, consisted of these organisms. The species figured by Ehrenberg (Passat- Staub und Blut-Regen, 4to, 1847, and Amer. Jour. 8ci., II. xi. 372), include 39 species of siliceous Diatoms (Fig. 157, 1-65); 25 of what he calls Phytolitharia (Fig. 157, 66-104), besides 8 Rhizopods. The following are the names of the Diatoms : Nos. 1, 2, Melosira granulata; 3, M. decussata; 4, M. Mar chic a ; 5-7, M. distans ; 8, 9, Coscinodiscus atmosphericus ; 10, Coscinodiscus (?)/ 11, Trachelomonas levis; 12, Campylodiscus clypeus ; 13-15, Gomphonema gracile ; 16, 17, Cocconema cymbiforme; 18, Cymbella maculata ; 19, 20, Epithemia longicornis; 21, 22, E. longicornis; 23, E. Argus; 24, E. longicornis; 25, Eunotia granulata (?) ; 26, E. zebrina (?) ; 27, Him- antidium Monodon (?); 28-32, Eunotia amphioxys; 33, 34, Epithemia gibberula; 35, Eunotia zebrina (?) ; 36, E. zygodon (?) ; 37, Epithemia gibba ; 38, Eunotia tridentula; 39, E. (?)lavis; 40, Himantidium arcus ; 41, 42, Tabellaria; 43, Odontidium (?) ; 44, Cocconeis lineata ; 45, C. atmospherica ; 46, Navicula bacillum ; 47, N. amphioxys ,* 164 DYNAMICAL GEOLOGY. 157. 37 "-"""iinniintinnrJl 60 63 inmiV.l....U..I......,, U....U .., U .. JJ; --.U.A ^l-^^ ^ T 67 Diatoms and other microscopic organisms of a dust shower. Ehrenberg. THE ATMOSPHERE AS A MECHANICAL AGENT. 165 48,49, N. semen; 50, N. serians ; 51, Pinnularia borealis; 52, P. mridula ; 53, P. viridis; 54, Mastogloia (?); 55, Pinnularia cequalis (?); 56, Surirella craticula (?); 57, 58, Synedra ulna; 59, Odontidium (?) ; 60, Fragilaria pinnata (?) ; 61, Mastogloia (?); 62-65, doubtful. A shower which happened near the Cape Verd Islands, and is described by Darwin, had by his estimate a breadth of more than 1600 miles, or, according to Tuckey, of 1800 miles, and reached 800 or 1000 miles from the coast of Africa. These numbers give an area of more than a million square miles. In 1755, there was a "blood-rain" near Lago Maggiore, in northern Italy, covering about 200 square leagues, which made an earth deposit in some places an inch deep ; if averaging two lines in depth, the amount for each square mile would equal 2700 cubic feet. The red color of the "blood-rain" is owing to the presence of some red oxide of iron. Ehrenberg enumerates a large number of these showers, citing one of the earliest from Homer's Iliad ; and among those whose deposits he examined he distinguished over 300 species of organisms. The species, so far as ascertained by him, are not African, and 15 are South American. The zone in which these showers occur covers southern Europe and northern Africa, with the adjoining portion of the Atlantic, and the corresponding latitudes in western and middle Asia. ANGLE OF REST OF FALLING SAND OK GRAVEL. The angle of rest in falling sand or gravel varies with the size, density, shape, and smoothness of the grains ; and also with the amount of moisture or water present among them, little moisture causing adhesion of grains, much water producing a flowing mud. With no friction, as is essentially the fact in the case of the particles of a liquid, like water, the angle is null ; with ordinary dry sand, 30 to 35 ; with ordinary volcanic cinders, 33 to 40. Instructive experiments may be made by inserting vertically a graduated rod at the center of a circular board graduated similarly from its center outward, and then dropping over the board about the rod sand of different kinds, the ratio of height to radius giving the angle. The author obtained in this way for dry angular quartz sand about 0-005 inch in radius, the angle 35 20' to 36 30' ; for iron-sand, of like fineness, 33 10' to 33 40' ; for new (untarnished) shot, No. 10, very fine, 20 12' ; same, No. 4 (coarser), 27 50' ; same, No. 3 (buck-shot), 29 40' ; and with tarnished shot, a higher angle. When deposition is around a center, or pericentric, the resulting form is approximately conical, varying with irregularities in deposition through the winds and other causes. ATMOSPHERIC PRESSURE. Variations in atmospheric pressure, which may amount to two inches of the barometer in a few hours, or half as many pounds per square inch, are supposed to influence the resistance of the earth's crust to earthquake movements, and to volcanic eruptions. The tide-like movements in large lakes are attributed to other causes. 166 DYNAMICAL GEOLOGY. IV. WATER AS A MECHANICAL AGENT. (1) General sources of activity. (a) Water does mechanical work in each of its three states, the liquid, solid, and gaseous state (or that of vapor). Only the first and second states are here considered, the third coming more conveniently under the head of Heat. In the liquid state it constitutes rivers, lakes, oceans; in the solid, snow, ice-crusts, glaciers, and icebergs. Unlike the aerial ocean, it has a defined upper surface ; and the basement on which it rests has usually no disturbing influence. (6) In rivers, water derives its energy from gravitation ; it works as it falls, and arrives at its zero of action on reaching the lowest level to which it can fall. It reaches only temporary or approximate zeros in lakes, except when the lakes are like the ocean in having no outlet. Winds make rela- tively feeble currents and waves in large rivers. (c) In the ocean, water has three prominent working agencies: (1) the tidal wave ; (2) the wind-waves and currents, both the regular winds, like the trades, and the winds of storms, each producing waves and also currents of greater or less depth and velocity; (3) the resupply currents caused by the sun's heat, which in evaporation removes surface waters, and, in the expansion of water, diminishes its density. Gravity acts toward a restora- tion of the equilibrium that has been disturbed, whether the disturbance be due to the tidal wave, wind-waves, currents, or heat, and in response also to changes in atmospheric pressure. (d) Lakes of large size, like the ocean, have wind-made currents and waves, and movements due to evaporation, and sometimes appreciable tidal waves and currents. Those of small size are often only still-water incidents in the courses of rivers. Winds over large rivers may slightly quicken, or retard, the flow. Over great lakes, they may make decided onward movements, which pile the waters, tide-like, on leeward shores, as sometimes about Duluth at the western end of Lake Superior, occasioning an under current of escape. But over the ocean they are in all parts a prominent source of currents, and in the tropics, as has been stated, the " trade winds " originate, according to some physicists, the Atlantic and Pacific tropical oceanic currents. (e) Owing to the earth's eastward rotation, increasing in rate of surface velocity from the pole to the equator as the cosine of the latitude, flowing waters in the northern hemisphere, whether of rivers or the ocean, and whatever their source, are thrown toward the right side as they advance, and in the southern hemisphere toward the left side. The result is seen in the lagging of the Labrador current against the west side of the north Atlan- tic; in a like effect on the correlate current in the north Pacific; and in the eastward course of the Gulf Stream north of the parallel of 35. It has also been observed along rivers in many parts of the world where the deposits intersected are earthy, and the pitch of the stream is too small for erosion at bottom. They are marked along the great rivers of Siberia and European WATER AS A MECHANICAL AGENT. 167 Russia, on others in southern France, on the streams intersecting the low land of the Atlantic border of the United States (Kerr), and on those of southern Long Island (E. Lewis). It is shown that in streams the difference between the surface and bottom velocity accounts for this erosion of the right bank, with deposition at the left, thereby making the right steeper and placing the deepest part of the stream near it. The extremely slow transverse motion will be combined with that down stream, so that the actual motion will make a very small angle with the direction of the channel. (A. C. Baines, Am. Jour. Sci., xxviii. 1884.) (2) Kinds and methods of work. The kinds of work done by the mechanical action of waters, whether in rivers, lakes, or oceans, are in a comprehensive way (1) Denudation; (2) Transportation; (3) Deposition of the transported material, making usually stratified deposits. DENUDATION. Denudation is going on wherever any rock materials or rocks are within reach of moving waters. It is called erosion or excwvation, when the work is the making of valleys, and degradation, when it is the wearing down of hills or mountains. But the term denudation covers both processes. Another style of work under it is that of planation, or the making of flat surfaces by the shearing action of spreading waters, and by deposition up to the surface, or to a common level. The worn material derived from the wear of rocks is called detritus, because made by wear; and also after deposition, sediment, because deposited usually from waters. Sedimentary rocks derive thence their name. Silt, the finest of mud, occurring in the bottom of estuaries and elsewhere, and ooze, soft, sticky mud, are extreme results of the grinding process. The term deposit is a general one for an accumulation made by any natural method. Denudation depends for its effects on the varieties and conditions of the rocks subjected to it not less than on the powers of the agent, water. It is facilitated not only (1) by softness or fragility of terranes, but also by (2) their subdivision into thin layers ; (3) a loose junction of layers ; (4) alternation of yielding layers with firmer layers ; (5) vertical joints or fractures, and especially multitudes of surface cracks or rifts. (6) Boldness in position is also favorable ; for high bluff fronts feel the force of blows of water proportionally to their verticality, and also have gravity to aid in removing loosened material, and to produce rendings where water descends in vertical crevices. (7) Moreover, angular concavities or cavernous open- ings and projecting points in walls give the waters great advantage. (8) A horizontal position in the bedding of cliffs or walls is especially favorable, because a little removal below undermines, and may cause great downfalls ; and, besides, walls and cliffs are thus kept vertical, for the long continuation of the work. (9) Above all, denudation is facilitated by the weakened con- 168 DYNAMICAL GEOLOGY. dition of rocks, due to decay through chemical methods, and to the superficial riftings and fractures attending chemical changes, organic growths,- freezing, and the alternating of cold with heat occasioned by the sun. The methods of denudation are (1) by water-strokes, or the simple impact of water; (2) by abrasion, which includes (a) wear of rocks by means of the stones and earth carried or thrown against rocky surfaces ; and (b) wear of transported stones or grains by their mutual friction or corrasion. By these means much of the shaping of the earth's surface and the trituration of rocks to earth has gone forward. Abrasion becomes a shearing action in planation and terrace-making. 1. Impact of water simply. In the flow over a smooth surface of rock pure water has no abrading effect. But when thrown in masses, in the form of plunging waves or torrents, into cavities of rocky bluffs or against bold projections, great results may be produced. Blocks of many tons' weight along a shore, if resting on a surface but slightly inclined toward the deeper water, will slip downward with each stroke. The force of the impact of flowing water is expressed in pounds, by the general equation P = 0-9702wsv 2 , in which v is the velocity in feet per second, s is the greatest transverse section of the body in square feet, n a coefficient varying with the form of the body, the value being ascertained for any particular form by trials ; and 0-9702 is the quotient from dividing the weight of one cubic foot of water (62^ pounds) by 2 g (p. 174). Supposing the greatest transverse area to be 1 foot : for a simple plate the value of n is 1-86; for a cube, 1-46; for a sphere, 0-51 ; for some rounded forms, only 0-25. If the hemispherical end of a cylinder faces the current, the impact is half less than if the flat end were in front. In accordance with the above, the force of impact against a flat plate a foot square, in a current of 5 miles an hour (or 7 feet per second), will be nearly 100 pounds ; in one of 20 miles an hour (4 times 5), 16 times that for 5 miles, and so on. On the other hand, if the surface struck is a hemispherical concavity, the impact would be very much greater than for a flat surface, the value of n being about 2 for a hollow hemisphere with the concavity to the current. The principle is illustrated in the connec- tion between form and resistance, or form and velocity, in a boat. These results of experiment and mathematical calculation show that while it is not possible to measure the force exerted in the movements of a river, the concavities and deep recesses or channels among the rocks along the sides of a rapid stream afford an opportunity for effective blows. 2. Abrasion ; Corrasion. The transported sand and gravel which is car- ried by water against the rocks within reach acts like the emery of an emery wheel, yet only under slight pressure. The particles, and especially the pebbles or stones, that are thrown by violent torrents against the surfaces of the solid rock, work more effectively, but less constantly. In a current of given velocity the larger stones carried abrade more rapidly than the smaller. At the same time the transported particles or stones, whether in rivers or on seashores, are wearing one another, and this corrasion tends to reduce the material to that fine impalpable state in which even slow-moving waters will transport them. WATER AS A MECHANICAL AGENT. 169 The coarser grains transported by the water suffer the most in cor- rasion, a grain a tenth of an inch thick wearing 10 times as fast as one a hundredth of an inch, and an inch pebble losing more in transportation a few hundred yards than a grain of sand of a thousandth of an inch in drift- ing for 100 miles (Sorby, 1880). Angular fragments of granite lose more by corrasion than rounded fragments. Ordinary sand-grains become rounded in a similar manner ; but those of the finest quartz-flour from glaciers (as that giving the milky tint to the Rhine at Strassburg) remain angular, instead of becoming corraded (Daubree, 1879). Shales and soft sandstones yield easily to abrading agents ; hard sand- stones and quartzytes much less so ; basalts, granites, very slowly, unless the wear is promoted by previous decay. Limestones are eroded easily because the material is soft and the waters may dissolve as well as wear away. Abrasion assorts in proportion to hardness. The softer materials first yield, leaving the harder. When granitic sands, made of quartz, mica, and feldspar, are exposed to beach or river action, the mica first floats off, because in thin scales; next the feldspar is reduced in the corrasiou to fine earth and is borne away ; and the hard quartz is left in grains. Thus at the same time, out of the same sand are made a bed of quartz sand, for a sandstone, and not far off it may be an argillaceous or mud-like bed, good for forming a shale. Rivers and beaches are thus ever at work when materials of the right kind are at hand. Where the flood-waters of a river, or the tidal-waters of the ocean, flow widely over shelving shores and bordering flats with little depth, the surface water as it moves onward is like a horizontally cutting blade ; and, while admitting of deposition up to its level, it shears off the surface with remarkable evenness, making, by this process of planation, flat shore- platforms and flood-grounds or terraces, such as occur along many river val- leys and sea borders ; and the plains are often at heights which make them evidence of ancient water levels. TRANSPORTATION AND DEPOSITION. The rate of denudation depends largely on the velocity of the transporting water. The transporting power increases as the sixth power of the velocity (Hopkins, 1844). With twice the velocity the weight of transportable par- ticles is increased 64 times ; or, if the particles are of the same specific gravity, the transportable particles, if the velocity is doubled, may have four times the diameter, or 64 times the weight. The stones, unless they have the specific gravity of water, are moved mainly along the bottom ; and being continuously under the action of gravity, the movement of each, like that of a projected cannon-ball, is in a long curve. It makes a series of leaps, rising from the bottom and returning to it, the length of the curve varying with the velocity and the specific gravity. The finest of sediment remains long in suspension, giving a cloudi- ness to waters ; and it has been suggested that a partial alteration of the 1TO DYNAMICAL GEOLOGY. feldspar to a hydrous alumina silicate is the cause. This finest of sediment falls on incipient freezing (Brewer, 1883). Very thin particles, like scales of mica, sink slowly, because the rate is that of particles (of the same density) having a diameter equal to the thickness of the scales. They are hence widely scattered by transporting waters. Transportation assorts in proportion to size and specific gravity. In accordance with the ratio of transportation to velocity, it is found, supposing the material to be alike in specific gravity, that a current of 4 miles an hour will carry along stones 21 inches in diameter ; of 2 miles, pebbles of 0-6 inch in diameter ; of f mile, fine sand about 0-064 inch in diameter ; of -J- mile, fine earth or clay, the particles 0-016 inch in diameter. Consequently, materials will be arranged over the bottom by velocity of flow, the coarser dropping first, the finer at greater or less distances beyond, and the finest floating on to other places of deposition. Again, sands of like size but varying specific gravity will be assorted on the same principle, iron sands (G = 5) being left behind where the current is, only sufficient to carry on garnet sand and other lighter kinds ; and garnet sand (G = 3-6), where the quartz sand (G = 2'6) is still kept in move- ment, so that several sorts of deposits may form by varying rates of flow. If gold dust (G = 18 to 20) were in the waters, it would drop long before the iron sand. The principle is used in ordinary gold washings. In drawing inferences as to rate of flow during deposition from the fineness or coarseness of deposits, there is need of caution, because flowing waters do not " scour " at the rates mentioned, unless the materials are quite loose. Very slight compacting at surfaces will hold the sands and earth down. Let any causes stir up the bottom, then the principle works well ; and in these modern times steamers up and down rivers, bays, and coasts, often occasion that stirring which favors scour, to the benefit of navigation. Professor Verrill has remarked that the shells broken up by fishes over the ocean's bottom make loose material easy of transportation by the Gulf Stream. An important exception to this relation between size of particles and hydraulic value, noticed and made the subject of special investigations by E. W. Hilgard, arises from the tendency of the finer kinds of sediment in fresh water, if the water is not absolutely quiet, to agglomerate their parti- cles, when not over 1 mm. in diameter, into larger particles, or to flocculate, as he terms the process, and so take the hydraulic value of coarser sediments. He shows that fine river deposits consist largely of such flocculated particles, and that the fitness of soils for tillage depends largely on the porous condi- tion thus' derived. Some characteristics of water. (a) A cubic foot of pure water at 62 F. weighs 436,495 grains, which equals 62-355 pounds, or nearly 1000 ounces avoirdupois 28,315 grams. The soluble impurities of ordinary river water are 0-000186 of their weight. (Murray.) Under a pressure of 1 atmosphere, water boils at 212 F. = 100 C. j and under 45 atmospheres, at 510-6 F. = 265-9 C. WATER AS A MECHANICAL AGENT. 171 (by When water freezes, it crystallizes in ttie hexagonal system : either in slender prisms ; in compact aggregations of prisms, making a mass of ice ; in small 6- rayed stars, as in snow ; or in feathery forms, as in the frost over windows and pavements in winter. In the thick crusts made over water in cold seasons, the prismatic structure is vertical except in a thin upper layer : a fact proved by means of polarized light. (c) The density of water is greatest at 39-2 F. = 4 C. From this point, it decreases, or the water expands, as the temperature falls to 32 F., the freezing-point, and as the temperature rises above 39-2 F. The specific gravity of ice, relatively to water as the unit, is 0-9178 ; and hence 11 volumes of ice make about 10 of water. (d) The increase of bulk of water when it becomes vapor, which it may at any tem- perature, is, under ordinary pressure, 1700 times ; and hence 1 cubic inch of water yields about 1 cubic foot of steam or vapor. The density of vapor at 212 F., taking air as 1, is 0-6235. In the further consideration of the subject of water as a mechanical agent, the natural subdivisions adopted are : 1. FRESH WATERS; including especially Kivers, Lakes, and Subterra- nean Waters. 2. The OCEAN. 3. FROZEN WATER, or Ice, Glaciers, Icebergs. I. FRESH WATERS. The several topics are the following : 1. Gathering of water into rivers and lakes. 2. Working-power of rivers. 3. Methods and results of denudation. 4. Transportation and deposition. 5. Special points in fluvial history. 6. Subterranean waters. GATHERING OF WATER INTO RIVERS AND LAKES. The fresh waters of the land come from the vapors of the atmosphere, and these chiefly from the ocean, but largely also from the waters and moisture of the land and its vegetation. The conditions favoring the making of large streams are as follows: 1. Large drainage areas, with high mountains on their borders. The cold summits of mountains are condensers of moisture, and sometimes perpetual condensers, when the country below is dry ; and their elevation gives force to the descending waters. Long slopes and combinations of those of differ- ent mountain ridges and ranges make the great rivers. In the Americas the mountain chains of the opposite sides of the continent contribute toward the Mississippi, St. Lawrence, Mackenzie, Amazon, and La Plata; and so it is in the Orient. Short slopes hurry off the waters to the sea and make small drainage areas. 172 DYNAMICAL GEOLOGY. 2. Abundant precipitation. The annual fall of rain (and snow) over the Mississippi drainage area is, for the eastern, or Appalachian part, 40 to 50 inches ; for the much larger west-central part, west of the Mississippi River, 20 to 25 inches ; for the western part, among the summits of the Eocky Mountains, 25 to 30 inches. In the vast Amazon drainage area the annual precipitation exceeds 50 inches both on the west and north, and is every- where ov^r 25 inches. 3. Upward waste, or that by evaporation, small. Under a hot and dry climate, and in the absence of forests, the waste is great. The western tributaries of the Mississippi lose a large part of the waters received in the mountains while descending the dry, bare eastern slopes. Where the Nile takes its rise, the annual precipitation is over 50 inches,* but it is not more than 10 through the lower two thirds of its course. An extravagant example of this waste is shown on the map of western Maui, on page 179, where there are great channels in the mountains and mere threads over the surface to the west where it seldom rains. 4. Downward waste, or that by gravity and soil absorption over the drain- age area, small. Not only loose sands, but also many sandstones are very absorbent ; and limestones, although nearly impervious to moisture, are often cavernous, and sometimes swallow up rivers. In western New South Wales the rivers take only 2J per cent of the precipitation, owing chiefly, it is stated, to the porosity of the sandstone of the region. Most lavas are porous and somewhat cavernous, but may lose these qualities by infiltration of earth from decomposition. Further, most stratified uncrystalline rocks are loose in bedding, and take off much water along the open spaces between the layers. Granite and other crystalline rocks make the tightest basins ; for they absorb little. Frozen or icy ground is like impervious rock ; almost all the water that falls over it goes to the rivers. Moreover, in cold weather evaporation carries off but little. Hence come the sudden rise and height of many spring floods in cold-temperate latitudes. In very dry and warm climates, where the precipitation is reduced to a few inches a year, rivers fail altogether, or flow only during the short rainy season. Between drying up under the hot sun and soaking away in the sandy soil, they are soon gone, and the lakes along their courses, or receiving their waters, may share their fate. Other sources of loss in surface waters are (1) the demands of vegetable and animal life ; and (2) the chemical combinations attending the decay of rocks in which hydrous minerals, as the hydrous iron oxide and clays, are made. . Of the water precipitated, the rivers may get 45 to 50 per cent over regions of crystalline rocks, as is true of the Connecticut River. In other parts of temperate latitudes the amount is usually a third to two fifths of what falls. But in warm latitudes it may be under one tenth. The mean annual dis- charge of the Mississippi River is about 25 per cent of the precipitation ; it WATER AS A MECHANICAL AGENT. 173 averages 19 J trillions (19,500,000,000,000) of cubic feet, varying from 11 trillions in dry years to 27 trillions in wet years. The Amazon, in the tropics, with a drainage area not twice as large, carries to the sea five times as much water as the Mississippi. The mean annual discharge of the Missouri River is about 3J trillions, or -^ of the amount of the rains over the region. The corresponding amount for the Ohio is 5 trillions, which is \ the amount of rain. (Humphreys and Abbot.) The Ganges carries down about 4 trillions annually, and the Nile 3 trillions. The rivers of England and Wales carry to the sea 18-3 inches in depth out of an annual fall of about 32 inches. WORKING-POWER AND ACTION OF RIVERS. 1. Energy from height of fall. It has been stated that in rivers the water works as it falls ; so that the amount of work done depends on the rate of fall along its course to its outlet, and the amount of water. In the mountain stream the slope of the water varies from 90, or that of a waterfall, downward to one degree and less. But in the large rivers it seldom exceeds 12 inches to a mile, and is sometimes but one third this amount. The slope of the Mississippi, from Memphis down (855 m.) is 4-82 inches per mile at low water; from Cairo, at the mouth of the Ohio (1088 m.), 6-94 inches ; and above the Missouri, from its source, 11 f inches. The Missouri, from its highest source (2908 m.), descends about 6800 feet, or 28 inches a mile ; but from Fort Benton to St. Joseph (2160 m.), about 11 J inches ; and below St. Joseph to the mouth (484 m.), 9i. (From Humphreys and Abbot.) The average slope of the Amazon for 3000 miles from its mouth is less than an inch, the descent in this distance being 210 feet ; of the Lower Nile, not 7 inches; of the Lower Ganges, about 4. The Khone is re- markable for its great slope, it being 80 inches per mile from Geneva to Lyons, and 32 inches below Lyons. The tidal portions of rivers, which have no slope with the rising tide, have a slope and a strong flow with the ebbing tide. During high floods the course of a river is shortened, because the minor bends are obliterated by the overflow, and where the channel is broad and open, the slope is commonly increased in amount and uniformity. Narrows between rocky bluffs act like a dam, and diminish the pitch above them, often spreading the waters into lakes, while they increase the pitch below. At such narrows floating ice often makes obstructions in the spring, which greatly increase the height of the waters. A dam higher up the stream, that obstructs or holds back the ice during its break-up, may save large areas from the flooding effect of the narrows. Narrows are sometimes created along streams by encroaching human "improvements"; but a narrowing either of a river's natural flood-grounds or its place of discharge may be a source of disaster. The water-power of the flooded river is safely controlled only by keeping the channel and outlet large enough to carry off all the water as it comes. 174 DYNAMICAL GEOLOGY. 2. The amount of work which a body of water, as that of a lake, can theo- retically do, on its descent to the level of the sea, is equal to the product of the height of the lake (h) into the weight ( W) of the water ; and hence Wh is an expression in foot-pounds for the energy or working-power potentially present in the lake. The amount of energy in a lake a fourth of a square mile in' surface, 10 feet in average depth, and 400 feet above the sea level, is 1,742,400,000,000 foot-pounds ; a power sufficient, could it be expended without loss, to raise a mass of stone weighing about 87,000 tons to the top of a mountain 10,000 feet high. If now the water were allowed to flow by a continuous slope to the sea level, without loss from evaporation, or from resistance of any kind (such as friction, etc.), its velocity would increase regularly according to the well-known law of falling bodies ; and, in this increase of rate, it would be constantly accumulating energy of motion, which would be the exact equivalent of the energy of position it was losing ; and when it reached the lower level its velocity would be 160 feet per second (about 109 miles an hour). In the case of falling bodies the relation between the vertical distance fallen through (h) and the acquired velocity (v) is expressed by the formula v = V2 gh, g being the force of gravity, usually taken at 32-2 (it is 32-165 at New York City) ; or, approximately (since 2 g = 64-3), by the formula v = 8 V^, or h = -fa v 2 . In actual experi- ence the theoretical result cannot be realized. On the contrary, the velocity of a stream does not increase uniformly as it descends, and when it reaches the sea, whatever the elevation at first, its velocity is in most cases nearly zero. This is owing to the fact that its energy, instead of being stored up, is being expended against the various resistances. encountered, that is : (1) In overcoming friction between (a) the molecules of the water itself; (b) the water and the bed of the stream; (c) the surface of the water and the atmosphere. (2) In impact, or blows against the rocks or earthy material of the bed and banks of the stream ; and in pushing sand or gravel along the bed. (3) In transporting earth, sand, or stones, held in suspension in the water. (4) In overcoming the friction between the transported particles and the bed of the stream, and the friction between the particles themselves; and also the loss from eddies made by the character or form of the bed or otherwise. By these means the energy is so far expended that no accumulation can take place except on portions of a stream where the pitch is uniform and considerable, and the bed is hard and smooth. In a waterfall, accumulation goes on during the descent ; but the whole energy of the stream is lost in the stroke of the water at the bottom of the fall, where it is converted into heat, a fall of 772 feet producing heat enough to raise the tempera- ture of the water 1 F. Owing to the rapid increase of velocity in the descending water of a waterfall, the stream in a high fall of small volume becomes divided up, the WATER AS A MECHANICAL AGENT. 175 parts running away from one another and finally separating into drops ; in which case, owing to the resistance of the air, the velocity, and therefore the energy, is almost wholly dissipated, and the fall becomes a veil of mist, swayed by the winds. 3. Velocity of rivers. The velocity of rivers varies (1) with their slope strictly the slope of the upper surface ; (2) with the volume of water; (3) with the friction of the bottom and sides which increases with the roughness of its surface, and the shallowness of the stream for a given volume ; (4) with the degree of uniformity of the cross-section and uniformity of course, for abrupt bends and shallo wings increase friction. In other words, among rivers a large stream of considerable depth, having a width not a score of times greater than its depth, and a uniform cross-section and course, will be least impeded by friction of the sides and bottom, and will work most effi- ciently. Over a bottom of ordinary kind the velocity is greatest along the line of greatest depth ; and in any given section the maximum plane of flow is at or near the surface, at about one tenth of the depth (Humphreys and Abbot), but varying between zero and two tenths. The retardation at sur- face is attributed by Professor James Thomson to the friction of the bottom and sides ; the eddying masses of water are thrown off by this friction, which modify the velocity in all parts of the stream, but most at the surface. The mean velocity is about four fifths of the greatest velocity ; or better, according to Humphreys and A.bbot, it is almost uniformly 0-955 of the velocity at mid-depth. The amount (in cubic feet) of water passing is equal to the product of the mean velocity into the area of the cross-section. When two streams unite without increase of pitch, the velocity is increased because the surface of friction is less than in the two flowing separately. Humphreys and Abbot, in their Report on the Mississippi River (page 312), give the following formula for calculating the velocity of large rivers. It is applicable strictly to a limited portion of a large river without bends. It is as follows : v= ( [225r,s|] ^ O0388) 2 , in which v is the velocity sought ; s, the sine of the slope ; and r, the mean radius = area of cross-section, , divided by p + W, or the length of the wetted perimeter (p) plus the width at surface. In the general formula, the sine of the slope = s = I = length of a limited portion of the river, h = h, + h u = difference of level of the water-surface at the two extremities of the distance Z, in which h, = the part of h consumed in overcoming the resistances of the channel supposed to be straight and of nearly uniform cross-section, and h,, = the part of h consumed in overcoming the resistances of bends and important irregularities of cross-section. In the equation for large rivers, above quoted, h,, is thrown out by the conditions. When a river expands into a lake, the velocity of flow is diminished because of (1) the greater capacity of the lake for a given amount of length ; (2) the decrease in slope ; and (3) the increased surface for evaporation. There is little movement in the waters that lie below the level of the outlet. 4. Periodicity in working-power. Rivers are periodical workers, owing to periodicity in the day, the seasons, and in the longer climatal cycles. 176 DYNAMICAL GEOLOGY. The changes of the day determine alternations in amount of evapora- tion, and, with greater effects, alternations in the supply from snow-covered heights. The night suspends part of the supply by the freezing that goes forward ; and the day starts the flow again, the effects reaching the plains below some hours after the change in the mountains, so that the night is often the time of greatest flow. With the alternating seasons, the changes are of great magnitude. All rivers have their annual season of quiet flow, when work is often wholly suspended, extending usually through most of the months of the year ; and then, once or twice annually, their periods of floods, when lazy streams become impetuous torrents, and narrow streams mighty rivers, sweeping over the bordering lands for miles, defying human attempts at management. In mountain regions, and especially those of dry, almost rainless climates, storms, called cloud-bursts, sometimes pass hurriedly and fill the narrow valleys to a depth of 100 feet or more in a few hours, doing quick, short, destructive work over small areas. The flood season is geologically the working-time of rivers. After their floods have passed, in which all work is of a broad sweeping style, rivers return to quiet action along the bed, and often are divided into several feebly chiseling strands along the channel. Sometimes only the stony bottoms of portions of the channel are left dry ; or, as in parts of Australia, there remains merely a string of small, distant muddy pools, in which only Fishes that are doubly equipped with breathing apparatus, like the Ceratodus, could survive. Eivers that rise in snowy heights, like the Rhine, Khone, and Danube, have their channels kept well filled in summer, the time of drought, because that is the melting-time of the snows. The flood season has its effects prolonged in many regions by the great natural reservoirs over the land the lakes and marshes. These stow away the surplus waters and let them out gradually. Many temporary lakes are made by floods which prolong greatly the period of high water under a con- dition that is convenient for mill-uses. Man makes reservoirs for the same purpose. Forest regions also keep the soil beneath them charged with moisture, and, like lakes, help to give rivers constancy of supply and uniformity of flow. And evil often comes when the forests are cut away ; for the rain waters then speedily reach the river-channels and may occasion alternate periods of wasteful violence and worthless feebleness. The cutting away of the forests in the French Alps (Dauphine) has led to uncontrollable erosion, despoiled fields, and impoverishment of the people ; and, in America, to annual seasons of dry mill-ponds, an immense sacrifice of available water- power, and the desertion of many a mill-site. Where a river has its rainy region confined to the mountains about its source, and flows below through dry plains, the floods travel gradually down the stream, losing by evaporation and soil absorption as they flow on. There is often much hard work done in the mountains, and little below. WATER AS A MECHANICAL AGENT. 177 The floods of the Nile commence in southern Abyssinia (where the annual fall of rain is 50 inches or more) in April, and reach Cairo in mid- summer, and exert their beneficial influence over all the flood grounds by the fertile silt deposited, which is estimated to amount annually to 140 millions of tons. The maximum rise is 40 feet, and the area of the region flooded is 2100 square miles. The distribution of tributaries influences the time and amount of floods. In the Amazon, the tributaries north of the equator are flooded during the rainy season of the northern hemisphere, and those south, during that of the southern. In this way many rivers, by their widespread arms, take advan- tage of the differences in the seasons or climates of the distant countries whence they get their supplies. The floods of the Amazon convert the larger part of its 500,000 miles of silvas into one great lake ; 3000 miles up the river, an elevation above tide of only 210 feet is reached. The Mississippi hardly feels the great floods of the Ohio unless they come when the Kocky Mountain tributaries are also flooded ; and these western tributaries are so widely distributed and so large that they may make successive floods, or pour in all together in one vast deluge, giving the Mississippi in some places below the Ohio a breadth of 50 miles. At high water the flood-level is 70 feet above low water at Cincinnati, 51 on the Mississippi at Cairo, and 17 at New Orleans. The cycles of rainy and dry seasons sometimes seem to correspond with the sun-spot cycle of 11 years ; and greater cycles include 4 or 5 of the 11- year cycles. No definite conclusions have as yet been formed regarding this point. 5. Causes tending to determine the direction of draining courses. The chief causes are the following. As regards, (a) Slope. The steepest descent accessible. (b) Surf ace- form. A depression leading downward to concentrate the waters from a large area for work. (c) Basement rocks. The belt of least resistance to wear. In the case of upturned strata, whether folded or in monoclines, the belt of weaker rock in the line of strike ; or over folded rocks, the course of a region of warped strata between the extremities, overlapping or not, of the folds (page 388). (d) Fractures, faults. The courses of great fractures and faults, and especially those attending the flexing of rocks in mountain-making, as, for example, those which determined the location of the Great Appalachian valley of eastern Tennessee and its continuation northeastward (page 356). (e) Meteorological conditions. The belt or region of greatest precipi- tation. DENUDATION. 1. Work of the rain-drop. Denudation by simple impact of water com- mences with the descending rain-drop. The drop makes a shallow impres- D ANA'S MANUAL 12 178 DYNAMICAL GEOLOGY. 158. Drop-made columns. D. '87. sion on soft earth or mud by denudation, which is circular or elliptical, according as the wind blows or not. These impressions, if they escape obliteration by succeeding drops and are soon covered by a layer of sediment, become " fossil rain-marks," and many surfaces so marked exist in the older rocks, bearing evidence as to former rains, and also as to the above-water level of the surface rained on. It may have been a mud-flat exposed between high and low tides. When the drops strike a gravel bed, stones in the gravel will protect the material directly beneath, while erosion around may cut away the material, and leave standing slender columns, each capped with a stone, as monumental evidence of the work done. A miniature specimen of this work was observed by the author in 1887, alongside of the path leading down into Kilauea. It had been produced by drops falling from shrubbery, wet with the heavy mist of the night, to a bed of earth, three or four feet below. A portion of the scene is represented, natural size, in Fig. 158. Columns of 10 to 30 feet are often made out of beds of gravel, glacial drift, and the like. Fig. 159 represents a case near Antelope Park, on a small trib- utary of the Kio Grande, where a bed of tufa, over 500 feet thick, contains large stones. The waters of the rains descending along the surface of a vertical wall first made, beneath the stones, bas-reliefs of columns, and then the free columns j and, in the end, an area three miles long and half a mile wide was thickly covered with the columns, many 60 to 80 feet high, and some 400 feet (Endlich, 1875). The power of water-strokes is well illustrated by the effects in gold-washings from a jet under a head of pressure derived from the water in an elevated reservoir, as in California hydraulic mining. The beds of compact auriferous gravel gradually return to their original condition of loose earth and stones, although struck only by a mass of pure water. At Niagara, the spray made by the waterfall, carried forcibly into an open chamber behind the fall, causes the wear of the shales (James Hall). 2. The excavation of valleys ; Denudation. Ero- sion, excavation and denudation, or land-sculpture, are parts of one process. The simplest illustrations of the subject are afforded by the great, gently sloping, volcanic mountains, made up chiefly of stratified streams of basaltic lavas. In them, the slopes are but 5 to 10, and conditions determining direction of drainage are in general reduced to two, the first and the last of those mentioned on page 177. The facts here presented are from the author's observations of 1839-1841, pub* lished in his Exploring Expedition Report, 1849. 159. Rain-made columns x "04. Endlich, '75. WATER AS A MECHANICAL AGENT. 179 The earliest stages are well illustrated in the Hawaiian mountains. One of them, Mount Loa, 13,675 feet high (see Figs. 227 and 229), is still active ; consequently it is without river valleys or gorges. Another, Mount Kea, 13,805 feet, has many gorges on the wet or windward side, extending upward from the coast, where they are several hundred feet deep ; but they go only half-way to the top. The leeward side is yet unchanneled. The map here introduced is that of the adjoining island of Maui. 160. On eastern Maui, the cone, 10,000 feet high, has a somewhat less recent aspect in its rocks than that of Mount Kea. It has channels on its wind- ward slopes, some of which reach up to the edge of its great crater ; but on the leeward side only narrow trenches that seldom contain water. At the same time, western Maui, nearly 6000 feet, has profound valleys in place of the many small ones, marks of very long exposure to denuding agents ; and another island of the group farther west, Oahu (Fig. 257), is like Maui in having a western volcano in ruins, a few crests and profound valleys in place of even slopes, and an eastern volcano of much more recent aspect, though more gorged than eastern Maui. But it met with a disaster in which over half of its mass sunk beneath the ocean, leaving a precipice for 20 miles facing the northwest or to windward. The nearly vertical surface has con- sequently a range of alcoves, finely illustrating this style of mountain archi- tecture. To the northward the alcoves are lengthened into gorges. Moreover, over eastern Oahu the winds pass the summit of the precipice before the cold heights have deprived them of their moisture, so that the leeward slopes take- 180 DYNAMICAL GEOLOGY. it, and show the fact of this reenforcement of the streams in the depth of the valleys. Finally, in Tahiti, as is shown in the map below, the work of erosion is in a, sense completed, in spite of the general covering of vegetation. The few great valleys, which here take the place of the many of the early stages of erosion, extend to the coast ; and these valleys, instead of narrowing to the 181. Map of Tahiti, the coral reefs excluded; the lower side is the northern, or that toward the equator: PP, village of Papenoo; M, of Matavai; P, of Papaua; T, of Toanoa; P', of Papieti, the largest; P", of Punaavia. The valleys are named from the villages on the coast at their termination. Wilkes' Exploring Expedition Report. summit, widen ont and stop off abruptly under precipices of at least 3000 feet. Some widen at their head into great amphitheaters or circs (the "cirques" of French authors), illustrating well the origin of such amphi- theaters. In the above examples, the rains and mists of the higher and cooler WATER AS A MECHANICAL AGENT. 181 parts of the mountains, and especially those of the windward side, are the source of the water. The slopes collect it as it descends into streamlets; these increase toward the foot, where the valley, as Mount Kea shows, first takes shape. The diagram Fig. 162, although greatly exaggerated in angle of slope, that of the line AB, will serve to illustrate the steps of progress. In the early stage a valley forms toward the base of the mountain, having its bed 162. 163. along Im ; and later along no. On reaching o, the most of the descent of the declivity is made : the waters from o to B have, therefore, little eroding power at bottom, and commence to erode laterally during freshets, under- mining the cliffs on either side, when the rocks admit of it, thus widening the valley and making a " flood-plain," or " bottom-lands," by deposition of the transported material in consequence of the slackened flow. The river, in this state, consists of its torrent-portion, Ano, and its river-portion, oniB. Along the former, a transverse section of the valley is approximately V- shaped, and along the latter nearly U-shaped, or else like a V flattened at bottom. The river-portion, oraB, usually exhibits, even in its incipient stages, its two prominent elements, a river-channel, occupied at low water, and k the alluvial flat, or flood-ground, which is mostly or wholly covered dur- ing freshets. As the waters continue their work of erosion about the summits, where the mists and rains are generally most abundant and often almost perpetual through the year, the next step is the eroding about the summit and the con- tinued deepening of the torrent-channel, making thus a precipice under the summit, or toward the top of the declivity ; in this stage, the course of the waters is ApqB, and later, ArsB. The stream has now (1) a cascade- portion, and (2) a torrent-portion, besides (3) its river-portion. The preci- pices of the cascade-portion may be thousands of feet in height; and the waters may descend in many thready lines, to unite below in the torrent. The mountain cone, in such a case, may have its top chiseled into a narrow, crest-like ridge or peak, with many vertical alcoves in the face of the preci- pice that were made by the falling and leaping streamlets. The next step in the progressing erosion, as Tahiti illustrates, is the thin- ning and wearing away of the ridges that intervene between adjoining valleys, in the higher regions where the descending waters are most abundant. It is in this way that two valleys (or perhaps more than two, by the wear of more 182 DYNAMICAL GEOLOGY. ridges) are combined into an amphitheater or circ. In Fig. 163, ArsB repre- sents the course of the stream, as in Fig. 162; and Ae/B the eroded ridge, which has lost at e much of its height. The ascent of the mountain by following the valleys is in such a case wholly impossible ; it can be accomplished only by finding the ridge that has held on to its summit connection with the peak. On Tahiti the ridge by which the author made his ascent to b, the peak called Aorai, about 6000 feet in height, narrowed to two or three feet, and for a short distance to a single foot, putting risks into the excursion, since the slope either side fell off for 1000 to 2000 feet at an angle of 60 to 70. Between b and a (the highest peak, Orohena) the " divide " was reduced in height more than 1000 feet, and the summit at b was but six feet broad. All the outlines of the original crater had disappeared. The lavas usually lie in beds dipping seaward, but those of the central precipices were without bedding. From the steps in the work of erosion over such isolated volcanic moun- tains it becomes evident that further progress would result in narrower, thinner, and if possible steeper ridges ; and, even when nearing the end, in sharp crests and ridges, which finally would be likely to disappear through weathering agencies. A flattening of the mountain would come at the very end, and not be a step in the progress toward it. These explanations show that a river rising in high mountains has (1) its torrent-portion, and (2) its river-portion, along which it is bordered by flood- grounds. The river-portion consists (1) of an upper section of rapid waters, along which erosion at bottom is continued, and the amount removed exceeds that of deposition ; (2) a section of feebler descent and slower flow, where the removal by erosion in floods does not exceed that of subsequent deposition, so that the stream has ceased efficient work. It has reached base-level as the condition has been termed by J. W. Powell. This base-level section may end below in a decrepit portion, over which deposition along the bed exceeds the amount removed in floods, so that thus a silting up of the chan- nel, and also a corresponding rise of the flood-grounds, go on. In the small Pacific islands these sections of the river-portion of a stream are short and not alwaj^s present. But on the western side of Maui there are remarkable examples of a decrepit ending ; for, while the valleys in the wet and cool mountains are wide and profound, as the map shows, the stream over the leeward (and hence nearly rainless) plain at the western foot is reduced to a narrow trench, which part of the time is dry. 3. River valleys of the continents. Over a continent where declivities are long, and the gently sloping plains have large extent, often hundreds of miles in width, each of the divisions of the river-portion of a stream, that of rapid-working waters and that of base-level, is often of great length. More- over, along many streams there are often several base-level portions, made by obstructions ; but where this is the case, as Powell remarks, it is evidence of the relatively recent origin of the stream; for the wear of ages tends to WATER AS A MECHANICAL AGENT. 183 remove the obstructions and reduce the stream throughout, or far toward its source, to a base-level condition. In New South Wales, Australia, where a friable Triassic sandstone 2000 to 4000 feet thick is the prevailing rock over large regions, the river-portion of some streams is continued from the coast, between nearly vertical walls of the sandstone, almost to the mountains, and there ends abruptly in the cas- cade portion of the source. The following figure illustrates the steps of progress : first, the cut of a torrent-channel to Cn l ; and then the retreat of the torrent portion by the continued wear, and the lengthening of a river- portion from n l to n 2 and so on to w 4 , n 5 , n 6 , when the torrent-portion is reduced to a series of waterfalls. Over the wetter interior portion of the 164. Ideal section illustrating progressing erosion of a stream. D. '49. country the valleys have often great breadth, and at the head widen into circs, owing to the many streams descending the steep sides ; but toward the coast, where the climate is relatively dry, the breadth does not much exceed that of the inclosed stream. A model of a system of erosion is often admirably worked out in the earthy slopes along a roadside, the little rill having its cascade-head, then its torrent-channel, and, below, its flat alluvial plain, intersected by the little winding water-channel; some of the ridgelets worn away in their upper parts, until two or more little valleys coalesce ; then, at times, the head of the coalesced valleys widened into an amphitheater, and the walls fluted into a series of alcoves and buttresses. The process of raising the bed and flood-grounds of a river is often pro- moted by the embankments made along the lower part of their course to prevent extensive flooding, and to increase the depth by scouring. On some Japan rivers, the beds, owing to the silting and the consequent making of artificial embankments, are now 40 feet above the plains over which they flow. In all improvements, it has to be remembered that the amount of water discharged by a flooded Mississippi cannot be lessened by choking it. It must and will have room to flow in, however desirable it may be to rob it for storehouses and dwellings. The flood-grounds of some large rivers extend scores of miles from tlie low-water channel. On the Mississippi, abreast of Tennessee, they are in some parts over 50 miles wide ; on the Amazon (up which the tides go 400 miles), over 100 miles; and on the Paraguay there are lagoons 300 miles in length. 4. Bends. Where the pitch of the stream is very small, any obstruction, or inequality of bottom, that throws the flow of maximum velocity to one side 184 DYNAMICAL GEOLOGY. of the axial line, causes it to strike and erode the bank in front and deepen the water, and to transfer the sand or earth removed by the erosion to the opposite bank of the stream for a sand-flat ; and it thus commences a curve in its course, which may become a deep bend ; and this bend may continue the action and be the occasion of a succession of such windings. The length of the Mississippi between the mouth of the Ohio and the head of the passes at the Gulf of Mexico is 1080 miles, while the actual distance in a straight line is about 500 miles. Cutting off a bend to shorten the distance along the stream increases at the place the pitch, and thereby the velocity, and gives the waters greater eroding power. The flow, consequently, would deepen the channel. But it is likely also to erode the banks, and may carry away all the farming land the cut was intended to gain or make accessible. During great floods, a stream may cut oft' one or more of its bends, as has happened in the Mississippi, along which narrow loop-form lakes and dry channels have thus been made. Many examples are on record of gorges, hundreds of feet deep, cut out of the solid rock by only two or three centuries of work. Lyell mentions the case of the Simeto, in Sicily, which had been dammed up by an eruption of lavas in 1603. In two and a half centuries, it had excavated a channel 50 to several hundred feet deep, and in some parts 40 to 50 feet wide, although the rock is a hard solid basalt. He also describes a gorge made in a deep bed of decomposed rock, three and a half miles west of Milledgeville, Ga., that was at first a mud-crack a yard deep in which the rains found a chance to make a rill, but which in 20 years was 300 yards long, 20 to 180 feet wide, and 55 feet deep ; and Liais describes a similar gorge, of twice the length, in Brazil, made in 40 years. 5. Eddies, Pot-holes, Kettle-holes. Flowing water gathers into its current any still waters alongside, to fill the void behind, which the flow tends to pro- duce, and thus eddies and eddy currents are made. When alongside of a rapid current, any obstruction or shallowing causes there a diminished velocity; eddies become whirls, and the whirling waters bear around stones which abrade the rock beneath new stones being carried in to replace old ones as they wear out. This kind of boring often goes on with hardly more change of center than in a carpenter's work with his augur, and deep cylindrical holes have been bored into the hardest rocks. Under a waterfall a broad basin may be excavated in like manner. Pot-holes are usually from 1 to 6 feet in diameter, and 2 to 20 feet deep. Kettle-holes are nearly circular basin-like holes 50 to 150 feet and more in diameter, in stratified or unstratified sands, gravel, or drift. For some reason they have failed to become filled up to the level of the region around. With regard to some, at least, of those in stratified terrace formations (see page 299), the facts appear to indicate that the spots were originally holes of moderate size and depth in the surface beneath ; and that in the rush over the spots by the flood waters that deposited the stratified material, the waters kept them free of detritus by the whirl occasioned by the depth. WATER AS A MECHANICAL AGENT. 185 6. Waterfalls. The facts reviewed show that waterfalls are often a conse- quence of the alternation of hard and soft strata in the course of flowing waters. The hard strata resist downward wear; the soft yield easily. Down the waters go, working with new force from the fall ; hence they un- dermine the hard bed and thereby steepen the descent often to a vertical or even an overhanging front. The columns made by drops (page 178) partly illustrate the principle. The waterfalls about the head waters of rivers in the mountains have a different origin ; for the lofty precipices may be cut out of a single block of rock, as in the case of the central portion of Tahiti. These precipitous walls are a consequence of the prolonged erosion of a region until a larger part of the vertical descent of the stream is made at or near its head. Waterfalls far down the courses of rivers, like that of Niagara, are looked upon as evidence of the recency of that part of the channel which contains the fall (Powell). But those about the source in the mountains may be, on the contrary, a final result after a long era of erosion ; not the ultimate result, for the last end of the work would be the degradation and removal of the crested heights. 7. Features of mountains ; Forms made by water-sculpture. Elevations of all kinds have derived their existing features largely through water-sculp- ture. Tahiti was originally a lofty mountain, probably twice its present height, with low, nearly even, downward slopes in all directions, and only small unevennesses from the piling here and there of lavas through localized eruptions. It now is a mountain of peaks, crested ridges with lofty preci- pices, and vertical lines in all the features. But water has no need of a mountain mass to make the grandest of so-called mountains. It will work an elevated plateau, horizontal in surface, into mountain forms, and so make mountains without any upturning or uplifting except that of the plateau. The chief part of the features produced come from the alternation of hard and soft strata among the stratified rocks ; and these are greatly varied by the positions of the strata. The elements of this system of architecture are well illustrated in the figures on page 186 by Lesley, taken from his work on Coal and its Topography (1856), in which the author has given the results of extensive personal observation in the Appalachian region. The harder strata may be hard sandstone or limestone, and the softer, shale or crumbling sandstone. The first figure (165) illustrates the origin of a "table mountain" or "mesa" (Spanish for table), a hard layer making the top, and, by resisting wear, protecting the softer beds directly below it. The other figures illustrate other effects, under the same principle, in rocks having various positions. Figs. 166 to 172 are synclines, and 173 to 176, anticlines, of different forms, in three of which a valley has the place of the upward bend a common fact in the Appalachian Mountains. Monument Park in Colorado is a region of Tertiary sandstone carved into monumental forms by denuding processes, the winds having given finishing touches. As the view shows, the thin, harder layers in the sandstone make the caps and moldings of the monuments. 186 165. DYNAMICAL GEOLOGY. 166. 167. 168. 169. 170. 171. 172. 173. 174. 175. 176. 177. Sections illustrating results of denudation. Lesley. The Colorado Canon, along an east and west portion of the river, between the meridians of 111 and 115 W., 3000 to more than 5000 feet in depth, affords grand illustrations of canon-making by water-sculpture. It was studied at some point, by Newberry in the Ives expedition in 1857-58, and more fully by Powell in 1869-1872. The rocks are horizontal or nearly so, and their edges make the vertical walls of the canon. In some parts the canon is cut out clean from side to side, with barely room between precipitous walls 3000 feet high for the stream, as in the " Mar- ble Canon," (Fig. 178) an eastern por- tion of the stream north of the west- ward bend. In other parts, a wide region intervening between the lofty walls of rock is sculptured throughout into moun- tains 3000 to 5500 feet in height, consti- tuting a group of architectural structures of unsurpassed grandeur. Part of one of the views from Captain C. E. Button's History of the Grand Canon (1882) is given on page 188. The principal mass to the left of the center bears the name of Vishnu's Temple, and has a height above its base of 5500 feet. The walls in the distance are the northern walls of the canon, and the foreground to the right in front is a portion of the opposite or south side. The deeper part of the canon, at the base of this side, containing the river channel, is not in the view. The peaks of the interior are higher than the Appalachians. As all is bare rock, the view is a remarkably instructive example of simple denudation. Erosion, Monument Park, Colorado. Hayden. WATER AS A MECHANICAL AGENT. 187 The effects of alternation in hard and soft layers, distantly spaced or grouped, appear throughout the scene. Besides, there are columnar lines due to vertical joints in the harder beds, or to rill-work down the vertical and sloping surfaces. 178. Marble Canon. From a photograph. The rock of the level region either side of the canon, and of the upper part of the walls, is Carboniferous limestone. Below are Paleozoic sand- stones and other limestones, descending to the Cambrian ; at bottom, in some parts, and for a height of 500 to 1000 feet above, the rocks are granitic. Many views of the Colorado Canon also show ranges of flat-topped mountain heights to the north, all of which have similar architectural features in their declivities, yet with peculiarities belonging severally to the rocks of the different periods represented. As described by Dutton, first, in the ascent to the summit, there are the Triassic "Vermilion Cliffs"; above these the white and red Jurassic ; then the pale yellow, gray, and brown Cretaceous strata ; and at the top great plains, the High Plateaus of Utah, the highest nearly 12,000 feet above sea level, which, unlike the slopes, are covered in some parts with forests. The vegetation at the sum- mit is accounted for, says Dutton, by the fact that the rainfall there is 30 inches a year, while only four to eight inches in the lower country. These mountain plateaus are remnants of formations that once covered the canon region and extended far away into Arizona. 188 DYNAMICAL GEOLOGY. The results are the more marvelous in that they are the work of the later part of geological time, commencing after the Tertiary era had begun. They show that to produce a mountain group, with summits thousands of feet above the plain around, it is only necessary that subterranean action should make a plateau of sufficient extent and elevation. Through the rains, the sculp- turing will all be done in time. Many of the so-called mountains of Colo- 179. View of peaks and ridges within the Colorado Cafion, south of the Kaibah Plateau. W. H. Holmes. rado and other parts of the Kocky Mountain region, and some of those in eastern America, as the Catskills in New York, and parts of the Alleghanies, consist of nearly horizontal strata, and are examples not of mountains made by upturning, but of plateaus carved into models of mountains. Scotch val- leys and elevations so modeled gave Hutton the first right ideas on this subject. The " harder " rocks in the scenes described, it is to be understood, are not granite, gneiss, syenyte, and the like ; they are not rocks of any particular kind. Granite may constitute the loftiest and boldest of ridges and moun- WATER AS A MECHANICAL AGENT. 189 tain needles ; but much of the granite of the world easily crumbles under atmospheric influences, and makes the tamest of scenery. Slates standing on end often bristle slopes with projecting ledges, and rise into lofty needles that defy the elements, like the Matterhorn in the Alps ; but other slates are fragile, and wear down into hills of gentle earth-covered slopes. 8. Climatal effects. Climatal causes also have great effect on the work of rivers. A wet climate produces abundant vegetation, which is more or less a protection from wear ; and in tropical regions it covers even precipices with ferns and other foliage. It also occasions rapid decay by the chemical and other weathering methods. Moreover, it sometimes makes deep, hard- working rivers, torrents that sweep away roughly, degrade rapidly and per- sistently and leave behind massive peaks, broad mountains, earth-covered slopes ribbed or belted by the more enduring beds, with gently swelling out- lines over the lower slopes, and foliage almost everywhere. A dry climate, on the contrary, as in the Colorado region, and that of Yellowstone Park, makes small streams or streamlets in the mountain valleys, many of which through much of the year are only threads of water, if not wholly dried up. They hence finish off with sharp and delicate outlines. All the variations of the beds in hardness are expressed in series of pro- jecting edges beneath the broader shelves and entablatures. The jointed structure of the thick, durable beds adds much to the diversity of surface, instead of insuring the removal of the beds. The winds also aid with lighter finger. In such regions, color from foliage may fail. But the dripping waters of the occasional rains, or the oozings through the steep mountain-sides, transfer to the surface the results of oxidations and deoxidations, and paint the walls with various delicate tints. Even alternations of half-hardened clay-beds and sand-beds, under such conditions, as Colorado scenery illustrates, may be cut into groups of pinnacles, turrets, and columns finished with capitals and bases which will last indefi- nitely ; for whatever the occasional supply of waters to the channels, it ends in reproducing the same features in the soft beds. Appalachian rains, as Powell says in his work on the Colorado Canon (1875), would soon oblit- erate much of Colorado scenery. The excavation of the Colorado Canon has been chiefly due to great floods; but the finishing work carried on within it has been of the gentler kind. TRANSPORTATION AND DEPOSITION. Amount of material transported and deposited by rivers. The materials transported by running waters are (1) stones, pebbles, sand, and clay or earth ; (2) logs and leaves from the forests, and sometimes trees that have been torn up or dislodged by the current ; (3) Mollusks and their dead shells, Worms, Insects, etc., attached to the logs or leaves ; (4) occasionally larger 190 DYNAMICAL GEOLOGY. animals, that have been surprised and drowned by freshets, or bones that have been exhumed by the waters. The amount of transportation going on over a continent, especially in seasons of floods, is beyond calculation. Streams are everywhere at work, rivers with their large tributaries, and their thousands of little ones spreading among all the hills and to the summit of every mountain; and thus the whole surface of a continent is on the move toward the oceans. The amount transported is a measure of the amount lost by the land, as well as of that gained by the river plains, lakes, and seas. The amount of silt carried to the Mexican Gulf by the Mississippi, according to the Delta Survey under Humphreys and Abbot, is about y^Vo" the weight of the water, or -^-^ its bulk; equivalent for an average year to 812,500,000,000,000 pounds, or a mass one square mile in area and 241 feet deep. The following table contains the ratio of sediment to water by weight, as obtained by the Delta Survey, and also the results of other investigations. Mississippi River, at Carrollton, by Delta Survey, Mississippi River, at Carrollton, by Delta Survey, Mississippi River, at Columbus, by Delta Survey, Mississippi River, at Mouths, by Mr. Meade, Mississippi River, at Mouths, by Mr. Sidell, Mississippi River, at various places, by Prof. Riddell, Mississippi River, at New Orleans, by Prof. Riddell, Rhone, at Lyons, by Mr. Surell, Rhone, at Aries, by Messrs. Gorsse and Subours, Rhone, in Delta, by Mr. Surell, Ganges, For the Danube, the ratio at low water is 1 : 33,000 ; at flood, 1 : 2400 ; for the Po, at flood, 1 : 300 (Lombardini) ; for the Meuse, at low water, 1 : 71,420 ; at flood, 1 : 2100 (Chandellon) ; for the Irrawaddy, at low water, 1 : 5725 ; at flood, 1 : 1700 (Login) ; for the La Plata at Buenos Ayres, 1 : 7752, at which rate it carries seaward about 224,000 tons of sediment each 24 hours, but dropping part of it along the 100 miles before it reaches the sea (Higgin). The annual discharge of sediment from the Ganges has been estimated at 6,369,000,000 cubic feet, or 378,100,000 tons. The Nile brings down annually nearly 150,000,000 tons. The bulk may be calculated, by taking 1-9 as the specific gravity of the material. Besides the material held in suspension, the Mississippi pushes along into the Gulf large quantities of earthy matter ; and the annual amount thus contributed to the Gulf is estimated to be about 750,000,000 cubic feet, which would cover a square mile 27 feet deep ; and this, added to the 241 feet above mentioned, makes the total 268 feet. This amount is equivalent to an average of ^Vff ^ a ^^ ammally from the whole drainage area of the river ; or, in other words, the area would be lowered by it, on an average, one foot in 4920 years. The Ganges works faster, the amount it transports to the sea being such as would lower its drainage area, on an average, a foot in 1880 years. All the rivers that enter the ocean or the seas over the land, are working in the same way, and with results to the continental surface mostly between these two extremes. itio. 1808 1449 1321 1256 1724 1245 1155 17000 2000 2500. 858, Time. 12 mos., 1851-1852. 12mos., 1852-1853. 9 mos., 1858. 2 mos., 1838. 1838. 14 days, summer of 1843. 35 days, summer of 1846. 1844. 4 mos., 1808-1809. at flood-time. WATER AS A MECHANICAL AGENT. 191 T. Mellard Keade estimates that the water (about 68,451,000,000 tons) which annually runs off from the area of England and Wales carries to the sea 8,370,630 tons of solids in solution, or 1223 parts in every 10,000 of water, consisting of about 0-95 of calcium and magnesium carbonates and sulphates, 0-166 of sodium chloride, and the rest nitrates, sodium carbonate, alkaline sulphates, silica, and iron sesquioxide ; and at 15 cubic feet to the ton, the denudations thus occasioned would equal one foot in 12,978 years. Prestwich obtained (1872), in a similar calculation, one foot in 12,000 years for the calcium carbonate carried off by the Thames from the chalk, greensand, and oolitic formations. The total annual denudation for England, from this source alone, is made 143-5 tons per square mile. The Rhine, according to Reade's calculations, removes about 92-3 tons in solution per square mile ; the Rhone, 232 tons ; the Danube, 72-7 tons ; the Garonne, 142 tons ; the Seine, 97 tons. From these data the conclusion is reached that over the world the average annual amount of rock-material dissolved and carried off by rivers is about 100 tons per square mile, of which about $ is probably calcium carbonate, A calcium sulphate, 7 tons silica, 4 tons each magnesium carbonate and sulphate and sodium chloride, and 6 of alkaline carbonates and sulphates. The annual amount of detritus brought down by the Danube is about -^ ^ of the water, or three times the amount of solids in solution. Taking the amount of solids removed mechanically at six times that in solu- tion, the total annual amount of denuded material for the globe would be 600 tons per square mile. While the land loses through erosion, the gain of the oceanic depressions, or of its borders, is exceedingly small. C. G. Forshey, after stating that the Gulf of Mexico has an area of 600,000 square miles, an average depth of 4920 feet, and is about 85,000,000,- 000,000,000 (85 quadrillions) of cubic feet in contents ; that its whole drainage area is 2,161,890 square miles, and the amount of fresh water it receives from this area is 37-78 trillions of cubic feet ; adds that if empty, it would take its tributary rivers at this rate 2250 years to fill it with water, or the Mississippi alone, 4000 years. Consequently, if all the rivers contribute on an average 2^00 tneir ^ u ^ k of detritus, it would take nearly 6,000,000 years to grade the depression up to the sea level, or for the Mississippi alone, about 11,000,000 years. This statement assumes that the bottom does not sink under the load. The quantity of wood brought down by some American rivers is very great. The well-known natural " raft," obstructing Red River, had a length, in 1854, of 13 miles, and was increasing at the rate of one and a half to two miles a year, from the annual accessions. The lower end, which was then 53 miles above Shreveport, had been gradually moving up stream, from the decay of the logs, and formerly was at Natchitoch.es, if not still farther down the stream. Both this stream and others carry great numbers of logs to the delta. DISTRIBUTION. The transported material of rivers is distributed (1) Along the channel, forming sand-flats, and mud-flats, and deposits also in the lakes of the drainage area. (2) Over the flood-grounds, supplying what these may annually lose dur- ing floods, and adding, in places, to their height, thus making fluvial or allu- vial formations, and, about lakes, lacustrine formations. (3) About the mouths of tideless rivers, making deltas on the sea border and on lakes. (4) About the mouths of tidal rivers, making estuary, shore and off-shore deposits. This last subject is deferred to the chapter on the Work of the Ocean. 192 DYNAMICAL GEOLOGY. (1) General distribution. The material carried down by a river is only to a very small extent gathered by the main stream from its head sources. The upper contributions are nearly all left high up the valley, and only little of the lighter sediment received usually continues far down the main trunk. A river has many contributors along its course, each pouring in coarser or finer sediment from cobble-stones to silt, according to its pitch, velocity, and resources ; and what each, in succession, contributes, the trunk stream dis- tributes and deposits about and below the place where received, dropping it near by if it is coarse, carrying it 011 for awhile if fine. Thus from the suc- cessive depositions of the material of the successive tributaries, the trunk stream produces its "fluvial formations." Such a formation may therefore be continuous through the whole length of the river-portion of the stream, but be exceedingly varied in constitution. In addition to all this, the river has often, in its course, steep rocky shallows and deep lake-like portions, if not true lakes ; and thereby the waters may have all grades of velocity to the gentlest. These different styles of flow will be continued to some extent through ordinary floods, notwithstanding the generally quickened move- ment; and this is another source of diversity in the fluvial depositions, since deposition is dependent on rate of flow, and the slow lake-like waters deposit fine material over their flood-grounds as well as along their banks and bottom. No pebbles or stones above a region of sleepy waters could get across to join a pebbly region made below by a tributary ; they must be ground up for transportation and then take their chance with other fine sediment. Depositions are made along broad channels when the flow is not rapid enough throughout the breadth to sweep all the transported material down stream. The chief current (or currents) makes its own deep, often stony, passage-way ; but either side the detritus drops because of the slower flow, and raises the bottom more or less, or to the surface, according to the degree of slowness, the eddying currents, and the supply and fineness of detritus. The trend of the shores, pitch of the bottom, and other causes, locate the swifter currents in the channel, and thereby tend to locate the banks or reefs. A stranded log may change the course of the former, and thereby the posi- tions of the latter. The lodging of drift-wood on a sand-bar may serve to in- crease the accumulation over it, and so change the bar into a wooded island. But high floods rob the bars at the same time that they add to them, or they may sweep them away, even if already an island, to form other bars and islands. They push along the movable detritus of the river's bottom, and also drop more to keep it generally at the old level. Thus all is movement and change along a river's channel, and deposits of all degrees of fineness or coarseness may be of simultaneous origin. When two rivers unite, one often makes a shoal in the other, by throwing a bar across the channel through the descending detritus of flood-waters. The waters of the upper Mississippi are pushed to the opposite shore by the contributions of a tributary, and a deep, still-water, navigable area is made above the junction, and rapids below it. Further, the tributary, if not in WATER AS A MECHANICAL AGENT. 193 flood at the same time, will have its mouth filled with sand-bars by the greater river, and often, also, in spite of its floods. This subject is well illustrated in Reports on the Mississippi and its Tributaries by General G. K. Warren. Sand-bars; obliquely laminated structure. A sand-bar, as shown by Gen- eral Warren, has usually a slight pitch up stream and a steep one at the down- stream extremity. The sand is carried on until the crest is reached, when it falls over and stops in the still water below. The stratification will corre- spond with the surface ; and as the sand-bar extends itself down stream by the additions to its extremity, the pitch of the down-stream extremity will determine oblique bedding parallel with it. The pushing of detritus along the bottom of a river must result in similar oblique bedding. But in both cases, oblique deposition will be followed by deposition in horizontal beds when the floods are declining, so that combinations of the two, often of a very irregular character, should exist in such deposits. (2) Over the flood-grounds. The flood-grounds or river-flats are under water only in times of floods. As the water rises in the channel, the velocity slowly increases; finally, where too great to be further withstood by the earthy banks, the waters spread laterally to the limits of the flats. They lose in velocity, and drop more or less of the material transported, resting long after the flood ceases for such deposition wherever the Surface is low. At the same time, the upper or surface portion of the flood-waters may shear off any accumulations above the general level, left by a former higher flood, or may work with the outer margin to extend the limits of the flood-grounds. The flood-grounds may thus lose from their surface, and, in parts, be cut away to open new channels ; but they generally gain as much as they lose or more. Along the sides of the channel they are often built up higher than elsewhere, thus making high banks which may be emerged during an ordinary flood. This raising of the margin takes place because of the deposition from loss of velocity by friction against the banks, and because logs and debris of other kinds are here stranded ; the debris serves to impede the velocity still more and thus is buried by the sediment. Further, an emerging bank often catches floating seed and grows shrubbery. These raised banks are most common along the lower, less vigorous portions of a river. They give the flood-plains a slope outward on one or both sides. Along the lower Mis- sissippi the pitch from the river amounts, on an average, to seven feet for the first mile. (H. & A.) As above explained, the deposits of the flood-grounds may be the finest of silt, or the coarsest of gravel and stones, according to the region and the pitch of the stream. The course of a tributary from a mountain region over the flood-plain of the main stream may throw into and across the earthy or sandy flats of the latter a wide thickening bed of stones or gravel. A flood-ground is properly the surface of a terrace ; and it is the lowest of the terraces where a valley has several. Terraces occur along nearly all DANA'S MANUAL 13 194 DYNAMICAL GEOLOGY. river valleys in the northern half of the United States, and in some of the southern half. Fig. 180 represents the terraces in the Connecticut valley, south of Hanover, N.H. The fluvial beds in these terraces consist of sand, gravel, or clay ; and ordinarily the stratification is very distinct. The sand-beds often have the cross-bedded stratification, illustrated on page 93, and in some places the flow-and-plunge structure. The height of flood-plains in a valley is determined approximately by the height of the floods. Floods raised to different levels would tend to make plains at different levels, or terraces, in the valleys of a country. If a high flood-level had thus made a high flood-plain or terrace, other terraces might 180. Terraces on the Connecticut River, south of Hanover, N.H. R. Bakewell, '49. be formed at different levels below this during the decline of the flood, if it were slow and intermittent in progress, by lateral removal of material, or by new depositions. The enormous floods from the melting ice of a glacial era would be subject to just such slowly progressing and intermittent decline, because of the thickness of the ice, and its long continuance about the mountains, and might, therefore, leave the valleys with one or several ranges of terraces. 1. Alluvial cones. The deposit of a rapid tributary at the base of the ridge it descends, where it meets the broad plain of the valley, piles up and makes a low elevation which is called an alluvial cone. The steeper cones are made by torrents at the base of rapid declivities, and have an angle of 10 or more, and those of large streams spread away at a very small angle, often 1 or less, and usually terminate in the main river of the valley, or a lake, with the form approximately of a delta. Figs. 181, 182 represent such cones from the upper Indus Basin, described and figured by F. Drew (1873). WATER AS A MECHANICAL AGENT. 195 The torrential stream in its flood-time cuts channels through the cone that later quiet depositions fill up. In Fig. 182 a cone is encroached upon (near d) by the river. Alluvial cones, of great size and low angle, occur at the base of the mountains in the Great Basin and in some other parts of the Eocky Moun- tain region, and have been described by Gilbert (1877-1890), Button (1880), 181. 182. Alluvial cone or fan-talus of upper Indus Basin. Triple alluvial cone, ibid. Drew. and I. C. Russell (1885). The gravelly deposits of this kind at the mouth of tributaries in the Connecticut valley and elsewhere were called deltas by E. Hitchcock, and the terraces over the surface either side of the stream, delta-terraces. 2. Lcess. The terrace-like deposits along portions of the valleys of the Rhine, Danube, and Mississippi consist of loamy earth called loess, which is peculiar in its absence of stratification, and often also in its vertical surfaces of fracture. They have remarkable extent along the Hoang Ho in China. The accompanying sketch, from Richthofen's great work on China (1877), shows its usual landscape features. Erosion reduces portions of its margin to a collection of towers, peaks, and deep and narrow labyrinthine passages ; and human contrivance makes dwelling-places by excavation. The thickness is stated to be in some places 2000 to 2500 feet. The material is a brownish yellow earth, containing land-shells and calcareous concretions. It occurs at several different levels along the river, 100 to 250 feet within 175 miles of the sea ; next, beyond a region of mountains, 1800 to 3500 feet ; after passing another mountain region, 4500 to 5800 feet ; and it is stated to extend to the most western sources of the river over 900 miles from the coast. The river at these levels, as in other cases of loess deposition, was probably lake- like. Long-sustained floods of the rivers in the mountains from melting glaciers are one explanation of the source of the material. Eolian drifting of dust from the salt-steppes of Siberia is Baron von Richthofen's theory, which the absence of a wind-drift structure renders improbable. Deposits occur in the Great Basin resembling the loess in absence of stratification and other characters, which are called adobe by Mr. I. C. Russell, from the name for sun- burnt brick, because this material is used for making the brick. It has usually a yellowish color, and is more or less calcareous. It is described as a result of the wash 196 DYNAMICAL GEOLOGY. and deposition of the ephemeral streams and the thousands of little rills that are occasionally at work over the surface of the dry regions : the annual precipitation is less than 20 inches. The deposits in some places are hundreds of feet in depth. The calcareous portion is attributed to land-shells. It is various in composition, containing 1 to 14 per cent of alumina, 19 to 67 of silica, and 2 to 5 of water, with 3 to 60 per cent of calcium carbonate. 183. Loess formation on the Hoang Ho, in the province of Shan-Si, China. Richthofen. Fine mud-like deposits are formed over the Great Basin in temporary lakes, called playas, produced by the overflow of rivers, the material of which is related to the preced- ing. The mud contains more or less of the saline ingredients of the evaporating waters. (3) Delta-formations. The larger part of the detritus of a river is carried to the ocean, or lake, into which it empties ; and it goes to form more or less extensive flats about the mouth of the stream. Such flats, when large and intersected by a net-work of water-channels, are called deltas; they are river- made, and reach a large size only where the tides are quite small, or are altogether wanting. The spread of a river into a delta at its mouth is a consequence of its enfeebled or decrepit state. Deposition is excessive and becomes an obstruc- tion to the flooded river, and consequently, besides keeping open one or two main channels, the waters cut new channels at flood-times, which may partly disappear and become replaced by others in future floods. The surface thereby becomes intersected by many lines of sluggish waters, small and large, which flood-time puts into temporary activity. The deposits have a slight slope seaward, and thus approximate in character to an alluvial cone (Gilbert), although a consequence of the floods of a stream in decrepitude, and not of one in a torrential or vigorous state. Through the flood-deposi- WATER AS A MECHANICAL AGENT. 197 tions over the various parts thus carried forward, along with the aid of encroaching vegetation, a large portion of a delta may become emerged. More than two thirds of the Mississippi delta in the ordinary state of the river are above water ; and over this part are plantations of rice, sugar, and cotton, and cypress forests. The area of actually productive land within it is 22,920,320 acres; of reclaimable land, 35,813 square miles. But if the river were unrestrained by levees, the highest floods would fill the alluvial basin and make a sea 600 miles long, 60 miles in mean width, and 12^ feet in mean depth. (C. G. Forshey, 1873.) The force of the flood-waters of the Mississippi is so great, and the amount of transported detritus so large, that the stream pushes out its long arms into the Gulf, by its method of deposit- ing load after load ; and it is still continuing its elongations at the extremities of the passes. 184. Delta of the Mississippi. The shallow waters within one to three miles of the main channel at the mouth of the Mississippi River (see map) are dotted with what are called mud-lumps, convex or low conical elevations, sometimes 100 feet or more in diameter, showing their tops at the surface. They originate in upheavals of the soft but tough bottom. Once formed, they discharge mud from the top, which gives to the material of the low cone the structure of a volcanic cone, the successive layers being, however, of mud, and but a fraction of an inch thick. They finally collapse ; and then the cavity of the cone sometimes becomes the site of a pool of salt-water, like the lake in an extinct volcano. They are formed, accord- ing to Professor E. W. Hilgard (from whose excellent description in the American Journal of Science, 1871, the facts here given are cited, and who adopts, in the main 198 DYNAMICAL GEOLOGY. point, the view of Lyell), through the pressure of the surface deposits on a layer of mud which overlies the Port Hudson clay, or older alluvium of the river. Some carbo-hydro- gen gas is given out, arising from the decomposition of animal or vegetable matters in the mud. The mud-discharges tend to increase the shallowness of the waters and push out the land into the Gulf waters. Mr. Hilgard states, in 1871, that Morgan's mud-lump, in the marsh of Southwest Pass, had been active for 25 years, and during the time the bars had moved gulfward a mile and a half. He closes his paper with a remark (vol. i. 435) relating to the distance to which the Southwest Pass must extend in order that there shall be no danger of mud-lumps within the channel. The Eads jetties have since then been made along this pass, in order to give it greater depth. It has secured the depth ; but with danger from this source still existing, as Professor Hilgard has observed. According to Humphreys and Abbot, the outer crest of the bar of the Southwest Pass, the principal one of the Mississippi, advances into the Gulf 338 feet annually, over a width of 11,500 feet ; and the erosive power is only about T L of its depositing power. The depth of the Gulf, where the bar is now formed, being 100 feet, the profile and other dimensions of the river, in connection with the above-mentioned rate of deposit, give for the difference between the cubical contents of yearly deposit and erosion 255,000,000 cubic feet, or a mass 1 mile square and 9 feet thick : this, therefore, is the volume of earthy matter pushed into the Gulf each year at the Southwest Pass. The quantities of earthy matter pushed along by the several passes being in proportion to their volumes of discharge, the whole amount thus carried yearly to the Gulf is 750,000,000 cubic feet, or a mass 1 mile square and 27 feet thick. As the cubical contents of the whole mass of the bar of the Southwest Pass are equal to a solid 1 mile square and 490 feet thick, it would require 55 years to form the bar as it now exists, or, in other words, to establish the equilibrium between the advancing rates of erosion and deposit. Hilgard has shown that, about New Orleans, the modern alluvium has a depth of only 31 to 56 feet, there existing below this the alluvial clay, etc., of the Port Hudson group. The delta of the Hoang Ho (Yellow River) extends along the coast from near Peking, on the north beyond the Pei Ho, to Hung-tse Lake, on the south, where it joins the plains of the Yang-tse-Kiang. The distance is 400 miles ; but the mountainous coast- province of Shan-Tung is to be excluded. From the coast, the delta extends westward for 300 miles. The river is here useless for navigation. The whole delta region would be under water during flood seasons except for drainage by artificial dikes and canals of great length; and these have required constant supervision. At long intervals, the great river has broken loose and swept over the immense area with devastating floods, and ended its mad career with change of channel from the river Pei Ho, or some place near it, on the north, to a southeast route ; or the reverse. In 1820 it occupied a southeast channel, emptying into the Yellow Sea, near latitude 33 N. By 1858 this channel was dry ; and after some years of uncontrolled waters, it took a new channel into the Gulf of Pe-chi-li, 300 miles north. In the autumn of 1887, a new break occurred near Kai Fung, in Ho-Nan ; but the waters instead of resuming the old channel which they left after 1852 took a course south from Kai Fung to the Cha, 70 miles, and then struck off east- southeastward to the Hoei Ho and the sea. The Chinese have succeeded in leading off the upper part of the wandering waters into the old channel mentioned above, leaving the more southern part in its new channel. The first of such changes recorded in Chinese annals occurred in 2293 B.C. ; a second, owing to Chinese care, not until 602 B.C. Several have occurred since. The Mississippi has its disastrous floods, but no chance for such changes. (4) Lakes. The discharge of lakes, like that of rivers, is (1) evapo- rational or upward; (2) gravitational or downward; and (3) surficial, 1 sea- 1 The word superficial is too various in its significations to express the right idea. Surficial is like surface in having for its prefix the French abbreviation sur in place of super. WATER AS A MECHANICAL AGENT. 199 ward. They either belong to the continental river systems, and are river- system lakes, or they are confined or imprisoned lakes. 1. Imprisoned lakes fail of the third method of discharge and are rela- tively few in number. They lie in basins or depressions that had been made or left in the surface by orographic movements, or had become cut off in some way from a river system, or possibly where the rocks, having little firmness, had been excavated by former glacier action. Some of small size occupy craters of extinct volcanoes. The Caspian Sea, Dead Sea, Great Salt Lake of Utah, and lakes in the Great Basin, are examples. They are most likely to exist under dry climates, where the supply of water is small and evaporation large ; and they may vary from dry beds to lakes in the chang- ing climates of the year. Some imprisoned lakes have had surficial dis- charge in former eras. A confined river system usually supplies the waters, and carries in what can be gathered from the rocks around by solution and otherwise, as explained on page 118. 2. Lakes connected with river systems occur in all climates and latitudes, and at various heights. They are often situated in lines or clusters over the nearly level summit region of a Continental Interior, where the great rivers are gathering waters and deciding on their courses. They sometimes occupy profound depressions in the earth's crust, like the Great Lakes of North America, or follow the nearly level median line of continental drainage, as the Winnipeg series of British America. The basins may be a result of geosynclinal movements, like that of Lake Superior ; or otherwise of orographic origin, as the intermontane lake basins of many mountain regions ; and even a consequence of the feeblest flexures of the earth's crust. They have commonly been made within the area of a river system by damming with transported material. Unusual floods may make barriers by local depositions ; more easily, tributaries may throw across a valley dams that have a degree of permanence ; still more effectively, ice may carry along gravel and sand and block the deep and narrow channel ; or better, in regions of glaciers, more formidable deposits of drift may make obstructions in valleys and give outlines to many lakes over nearly level regions. After a period of elevation when the valleys were excavated to great depths, a period of lower level may have come, in which the transport- ing waters were in great force and made obstructing deposits, especially when water and gravel were afforded in vast quantities for the purpose by a melt- ing glacier. Lake Geneva, in Switzerland, 45 miles long and 1095 feet deep, the surface 1230 feet above tide-level, is supposed to have been made in the way last mentioned ; and even also, Lago Maggiore, of northern Italy, which, although only three miles wide, is 2613 feet deep, with 1920 of this below the sea. Another view attributes the depth of Lake Geneva to a subsidence of the lake bottom since the Glacial period. Further, a large river in its more aged or decrepit portion may so wall itself in and raise its bed by depositions either side of and along its chan- nel, that every flood makes temporary lakes; and extraordinary floods may 200 DYNAMICAL GEOLOGY. carry off waters that excavate a course through the alluvium to neighboring depressions and thus make a more permanent lake. Salton Lake, in the southeastern corner of California, 130 miles long by 40 in greatest breadth, resulted, in July, 1891, from the overflow of the Colorado River on the west side below Yuma. The alluvial region either side of the river between Yuma and the head of the California Gulf, 50 miles distant, had been gradually built up by river depositions, until a large depression, Coahuila valley, now 300 feet below the sea where deepest, had been separated from the head of the gulf and left as a nearly dry desert basin. The flooded waters, pressing westward along the westward course of New River, succeeded in passing the low summit level, and then quickly excavated a way to the depression and filled it. Owing to the hot and extremely dry climate, evaporation will sooner or later make it an empty lake-basin, as it was essentially before. The river at Yuma is about 150 feet above the gulf. Nearly 100 miles north of the Salton Lake is Death Valley, 225 feet below the sea, also situated in the line of the California Gulf. W. P. Blake traveled over the desert in 1853 (Geol. Eeconn. CaL, 4to, 1858), and describes it as having, in general, a barren, clayey surface, with some saline springs along the margin and elsewhere. On the rocks of the shore, there was a thick horizontal belt of whitish calcareous tufa about 15 feet (where examined) above the level of the desert, indicating a former water level, and proving that the desert was the dry basin of a former lake. He found that the Indians had a tradition of the existence of a great lake filled with fish ; of its slowly drying up, and of a sudden return of the waters, when many were drowned. The recent event is evidently not the only one of the kind in the region. Other lake-basins have been made by glacier-damming (page 238), and possibly, as above stated, by glacier-excavation. Still others of small size are a result of underminings, especially through removals of clay-beds by pressure ; others have come from a damming against the sea by beach-made deposits (page 224), converting inlets into sea-border basins. The large lakes of the world, after the Caspian, are the Great Lakes of North America, Lake Baikal in Asia, and Lake Victoria in east Central Africa. The map, Fig. 185, gives the positions of the American Great Lakes, and the line of greatest depth, the deepest point in each, and also the limits of the several drainage areas. Lake Superior has an area of 31,200 square miles ; Huron, of 23,800 square miles ; Michigan, of 22,450 ; Erie, of 9960 ; Ontario, of 7240. The heights of the water above mean sea level are : Lake Superior, 601-8' ; Huron and Michigan, 581-3' ; Erie, 572-9' ; Ontario, 246-6'. The section, Fig. 186, shows their depths, and the extension below the sea level. (Schermerhorn, Amer. Jour. Sci., 1887.) Lake Chainplain is 402' deep, 300' of it below the sea level. The heights of some other American lakes are as follows : Winnipeg, 630' ; Lake of the Woods, 1640' ; Great Salt Lake, 4218' ; Yellowstone Lake, 7788' ; Shoshone Lake, 7870'; Great Bear Lake, 5931'. The Caspian has an area of 170,000 square miles, a depth of 500', and descends 90' below the sea level. Lake Baikal in Siberia (really among the high Altai Mountains and near Central Asia) is 397 miles long, 54 miles in maximum width, and has a depth in some parts of over 300 fathoms, nearly 500' of which is below the sea level. The great African Lake, Victoria, has an area of about 27,000 square miles, and is 3300 feet above the sea level. The Assat Lake lies in a depression east of Abyssinia, 600' below the level of the Red Sea, and is salt. Rivers tend to obliterate the lakes along them in two ways : by the depo- sition of detritus in their still waters and along their borders, and by erosion WATER AS A MECHANICAL AGENT. 201 at the outlet where the stream resumes its relatively rapid flow. The final result when reached is the conversion of the bed of a lake into a river channel. 185. SKETCH OF THE NORTHERN AND NORTHWESTERN LAKES Limit of Drainage Areas \ Line of Deepest Water. ^Deepest Sounding # Map of the Great Lakes. L. Y. Schermerhorn, '87. The smaller lakes are very feeble workers, and hence, owing to gentle trituration by the little waves, the shores are often muddy. Theoretically 186. Longitudinal sections of the lakes on the line of deepest water. Schermerhorn, '87. the waters of the lakes over high plateaus, like those of the head waters of the Mississippi, have great energy; but they usually lie without a chance to 202 DYNAMICAL GEOLOGY. show it. Occasionally a lake bursts its bounds, and produces in a few hours the devastating effects of the most violent of torrents. But such effects are rare, except where man has interfered. The large lakes have many of the characteristics of the ocean. The wind, waves, and currents are effective agents of wear and deposition along the shores, and about bays and the mouths of rivers. The waves work landward on shelving shores, as along the sea border, while a littoral current usually runs parallel, or nearly so, with the coast ; and between the two the depositions of sand and making of beaches and sand-bars take place. The nearly total absence of tides makes marked differences in the effects. The, change of level in seashore action with the tidal movements fails. Abrasion sets back the cliffs, but makes a sloping surface at their base. The tide on Lake Michigan has a range of three inches at spring tides and li at neap tides. Large oscillations of the surface are produced by storm winds, and lighter ones by floods in the region. On Lake Erie, at Buffalo, the difference between the levels produced by two gales, one from the S. W., and the other off shore, from the N. E., was 15|- feet (Whittlesey). Small but short tide-like changes of level, called seiches, a few inches in height, observed on Lake Geneva and other Swiss lakes, are attributed by Forel to local variations of atmospheric pressure an impulse so given producing a long-continued series of oscillations. Larger seiches are supposed to be due to earthquake shocks. For a thorough discussion of lacustrine methods of work under varying conditions of levels, see the Memoir of G. K. Gilbert on Lake Bonneville, U. S. G. S., 4to, 1890. Past geological ages had their fresh-water lakes as well as rivers. But the great lakes and rivers of the world belong to later history, the era of full-grown continents. Yet the lakes of greatest geological interest are not those of the present era, but of that next preceding. Those of North America formed over the emerging land of the Eocky Mountain region had great area, and received abundant debris for lacustrine deposits from a newly made mountain range. But another condition existed; for the great lake-basins were subsiding areas, so that the deposits continued thickening, as the subsidence made progress, until 5000 to 10,000 feet of beds were laid down, as the region of modern coral reefs is described, on page 149, as subsiding while the reefs thickened. These Tertiary lacustrine formations prove their fresh-water origin by containing remains of abundant fresh-water and terrestrial life, from Quad- rupeds or Mammals, of many more kinds than now exist in North America, to Snakes and Turtles, Fishes, and Insects and even Butterflies, besides leaves and other relics of the forest. AS A MECHANICAL AGENT. 203 SPECIAL POINTS IN FLUVIAL HISTORY. The history of rivers has been eventful. In the course of the geological past, drainage areas have sometimes changed to areas of marshes, lakes, or ocean; and again back to dry land, with perhaps new limits and slopes. They have experienced changes of level that divided and subdivided them, or forced part of a stream in a new direction for an outlet ; that annexed another stream, giving it a new head, and doubling its length, supply of waters, and mean pitch, as in the case of the Mississippi, which once had the Saskatchewan as its source. They have had portions buried under debris, and have been compelled to make long -circuits, and deep cuts, in order to effect a new connection ; or have been buried with all their fluvial deposits beneath floods of lavas, as on the west slope of the Sierra Nevada (Whitney), and so have made fossil river-channels, some of them to remain buried, others to regain their places wherever the surface conditions favored it. They have had their slopes increased by continental elevation, so that after reaching a state of feebleness, they acquired new energy and were set again to work at the deepening of their channels and the enlarging of their valleys ; or they have suffered from subsidences that have slackened the flow over the subsided region and brought on premature old age, or spread a stream into a lazy lake ; or by the coming on of a period of enormous precipitation, and of glaciers ending in glacial floods, they have once more been made young and powerful in denudation and transportation over the width of a continent. Furthermore, streams that originated over a formation covering a country, and derived their courses from its slopes and lines of weakness, have some- times been forced by the removal, through denudation, of that formation, to chisel down their channels into older underlying beds, and fix upon the latter, as far as possible, their original qualities. An example of a drainage area with such inherited qualities was described, in 1874, by A. R. Marvine (Hay- den's Report of 1873), from the slopes east of the Front Range of Colorado. The deposition of Triassic and other strata over the region was followed by its emergence, and the outlining of a system of drainage down the long slopes of the rising continent. But since then the new streams in their upper portion have cut through these strata to the older rocks ; and here the work of impressing the courses of the new canons on these older rocks is going on, mostly irrespective of their slopes and structure-lines. Twelve years earlier, J. Beete Jukes, of the Irish Geological Survey, treating of the mode of formation of some river- valleys in the south of Ireland (Q. J. G. S., 1872), brought out the same general idea that the drainage courses of the present time have often been determined by preexisting topography. A course of drainage derived from a formation that once covered the region is called by Powell superimposed drainage. Further, if the course of a river is a consequence of the structure of an upturned region, he terms it consequent drainage ; but if derived from conditions prior to the upturning, antecedent. (Exploration Colorado River, 1875.) 204 DYNAMICAL GEOLOGY. Buried river valleys. Rivers of the Sierra Nevada, in Tuolumne County, California, that had their channels buried beneath lavas in the later Tertiary, afterward, in a comparatively short time, cut new channels through the thick lava stream and the underlying rocks to depths 1500 to 2000 feet below the old channels. (Whitney, 1865, 1879.) They hence are strong evidence of increased precipitation, as held by Whitney, and also, according to LeConte (1879, 1886), of increased elevation in the mountains; and both conditions characterized the Glacial period which was in progress during part or nearly all of the cutting. Like evidence of elevation exists also in the river channels of southern California beyond the limits of the lava-flood, as observed by LeConte (1886), who thence concludes that the elevation extended along the whole length of the Sierras. The ultimate result of denudation over a continent is, as usually stated, the transfer of the mountains to the sea, bringing all to a nearly level plain. But the facts from Tahiti, explained on page 182, appear to show that the process would, as a general thing, first thin down the mountains to sharp peaks and ridges; and after this, the continuation of the thinning would ultimate in a general level given time sufficient. The Adirondacks have stood ever since Archaean time, with the height probably never less than 5000 feet ; and yet they are to a large extent in the Tahitian stage. But the streams of extensive drainage areas become to a greater or less extent base- leveled; and through the continued leveling work along them, with that of the minor tributaries, a wide region may be finally reduced approximately to a plain. Such a plain has been termed by W. M. Davis a peneplane, from the Latin for almost and plain; for it may still have ledges of the harder rocks and other irregularities of surface. An elevation of the land, and other causes indicated above, may expose such regions to a new base- leveling. The fluvial history of a country, it thus appears, may have great com- plexity, and require a large amount of study and an experienced judgment for its correct elucidation. SUBTERRANEAN WATERS. Water descends from the surface by gravity, filling all open subterranean spaces, and also the pores of the solid rocks. Its lower limit is determined by the earth's interior heat ; and the lower limit of outward discharge, by a level not much below that of the ocean's surface. At greater depths, conse- quently, subterranean water may be that of early ages in geological history, and in part the sea water in which the deposits were made, more or less modified in its saline contents and their amount by long contact with the various rocks. Not only the waters of the rains and rivers thus take a downward way through the porous rocks, between their sloping layers and along all crevices, but also those of lakes, which are sources of permanent supply, and pre-eminently those of the ocean. WATER AS A MECHANICAL AGENT. 205 The more solid crystalline rocks imbibe less than 0-2 per cent of water, and hold it so strongly by capillary attraction that when once filled there is little further change, if they are below the influence of surface droughts, and away from that of subterranean heat. But some sandstones are so porous that they give easy passage to the waters from above ; and unaltered strati- fied rocks generally have much open space between the layers. The amount of water contained in different rocks taken near or at the surface has been found to be as follows : porphyry, 0-012 per cent of the rock-mass ; a feldspathic granite, 0-0203 (Durocher, 1853); coarse granite, 0-37 per cent ; euryte, 0-07 ; milky quartz from a vein, 0-08 ; flint from the Upper Chalk, at Meudon, 0-12 ; but sandstone (Gres de Fontainebleau, near Meudon), 2-73; a Tertiary limestone (Calcaire grossier), 3-11 (Delesse, 1861). The Calcaire grossier will absorb 18-03 per cent of water ; a quartzose Tertiary sandstone, 29-00 ; the chalk near Issy, 24-10 ; a Silurian slate, near Angers, 0-19 ; granite, 0-12 (Delesse, 1861). Chalk will absorb 2 gallons of water per cubic foot (Prest- wich); the Old Red Sandstone (Devonian) of Gloucestershire absorbs 11-60 per cent; limestone of the Lower Oolyte, 12-15 ; Carboniferous limestone of Clifton, England, 0-70 (Wethered, 1882). The amount of moisture absorbed, after drying at a temperature between 150 F. and 200 F.,is as follows: for Potsdam sandstone, 3 specimens, 2-26 to 2-71 per cent; 3 others, 6-94-9-35 ; for Trenton limestone, 0--32 to 1 -70, the former for a black variety ; for some dolomytes, 10-0 to 13-55 ; a crystallized dolomyte, of the Calciferous formation, 4 speci- mens, 1-89 to 2-53 ; 2 other specimens, 5-90 to 7-22 ; for the Medina argillaceous sand- stone, 2 specimens, 8-37 to 10-06 (T. S. Hunt, 1865). A square bar of Triassic building-stone from Runcorn, England, 1-92 inches square and 14-92 high, being half immersed in a can of water, the water rose to the top by capillarity in 2V hours, taking in 4 ounces of water; and the same stone made in the form of a siphon, emptied a can of its water. The pore space was nearly ^ of the stone. (M. Reade, 1884.) 1. Flow of underground waters. In regions of massive or schistose crystalline rocks of close texture, there is no proper flow unless there are vertical fissures ; and then the water will descend to the bottom of the fis- sures, and there remain, or push off laterally if the space admits of it. But if the rocks are uncrystalline stratified kinds, the water flows downward along the surface of the less pervious layer, and soaks more or less through the others. Subterranean waters often come out on the faces of bluffs, and indi- cate the position of the more impervious layers by a belt of foliage above, kept green by the exuding moisture ; or they form springs or streamlets at the base of bluffs ; or they feed pools or lakes ; or make springs off shores below tide level. In regions of loose sand-beds and gravel-beds they generally find, at a depth of a few yards or scores of yards, a hard layer hardened by deposits of iron oxide or otherwise (called in popular language hard-pan}, which carries along the accumulating waters, and becomes a source of supply to the numerous wells of a village or city ; and the same hard layer, if sloping seaward, will afford water by boring, even out in a bay. In the deep sand deposits of the southern side of Long Island, where the seaward slope of the surface for the 6 miles to low- tide level is 1 : 265 feet, there is a water -plane 206 DYNAMICAL GEOLOGY. below, which slopes 1 : 425 feet, or 12 \ feet per mile. The discharge of water at sea level is so large, although dependent solely on the rains, that the city of Brooklyn, containing nearly a million inhabitants, has derived from it its supply of water through a series of reservoirs, constructed a little above the sea level. The water-plane is not that of a hard-pan layer. Its position has been determined by well-digging. Out of the 42| inches of rain (snow included) which annually falls, nearly 40 per cent becomes ab- sorbed and subterranean. The Brooklyn engineer, Mr. T. Weston, observes that these subterranean waters supply the small streams of the surface with the chief part of their water, and discharge a large amount into the sea ; and after a careful survey of a part of this southern slope, east of Brooklyn, 73-64 square miles in area, he reported that the water supply from the surface streams was, on an average, 22 per cent of the precipita- tion, or 30,000,000 gallons a day ; that 15 per cent additional came out along the shores of the bays ; and that at least 40,000,000 gallons per day might be obtained in reservoirs by proper arrangements. Mr. Weston holds that the water- plane is the upper limit of a water region which extends from this plane downward to and below the sea level, and that there is no hard-pan layer underneath. Friction and capillarity in the sands give it its height. A coral island but ten feet high and a few hundred yards wide, and consisting of coral rock up to the water level with coral sands above, generally yields, on digging down to the surface of the coral rock, a sufficient supply of water for its inhabitants, and all of it has come from the rains. The fresh water, moreover, is sufficient to exclude, by its sea- ward pressure, all ingress of salt water. If this is true on a coral island, the subterranean waters derived from the rains over larger lands should be very great. Moreover, the salt waters of the ocean do not penetrate far into the basement of a continent. An island may receive sea water to its center at some unascertained depth below the sea level; but not so a continent. 2. Force of flow. The force of the flow of subterranean waters is due to gravity, like the flow of surface waters. There is everywhere hydrostatic pressure, varying directly with the height of the supply, minus the loss by friction and capillarity. The height may be that of the neighboring hills, or of distant mountains, according to the range of the sloping rock-layers along which the water descends. It may be that of lakes small or large, for these bodies of water have the double duty of supplying above-ground and under-ground streams. While the hydrostatic pressure varies with the height of the water-supply, the extent of the region served by a single source will depend on the area of that source. Professor Edward Orton, of Columbus, Ohio, has proved that the hydro- static pressure in the Findlay oil-region, and also in Indiana, where the bor- ings descend to the Trenton limestone, reaching it at various depths to 1000 feet or more below the surface, is determined by the waters of Lake Superior. The level of the lake is 600 feet above tide level; and by adding this height to the number of feet at which the Trenton lies, in any case, below tide level, and calculating the hydrostatic pressure on this basis, he has found that it cor- responds closely with the actual gas pressure at each boring. He holds that this hydrostatic pressure determines the gas pressure in other regions ; and WATER AS A MECHANICAL AGENT. 207 187. hence that the pressure is rarely, if ever, due, as has been supposed, to the pressure of confined gas. The facts exhibit on a grand scale the influence of a large elevated lake on the conditions of subterranean pressure. Wherever subterranean water flows between nearly impervious sloping layers, so that it is confined to a given channel, it is like the water in a long inclined tube ; and on opening a hole through the overlying material it will rise in a jet, owing to the hydrostatic pressure. The height of the jet so produced is that of the source, diminished by the loss from friction and the resistance of the air ; it may be hundreds of feet. In the annexed cut (Fig. 187), ab represents a water-supporting layer; 6c, the boring ; and cd, the jet of water. Such wells are called Artesian wells, as they were first made in the district of Artois, in France. They are now an important means of securing water for irrigation and other purposes in various parts of the world. By this means abundant water is now obtained even on the seacoast region of New Jersey, from Cretaceous and Tertiary strata, and over various parts of the dry regions of Montana, Colorado, and Nevada, where arid sands have been covered thereby with foliage. But if the rocks are porous throughout, with no impervious layers, boring is of no avail. Borings in regions of metamorphic or crystalline rocks gen- erally prove failures unless a chance bed of decomposed rock extending down from the surface should be reached ; for such rocks have been consolidated and crystal- lized while under heavy pressure. Where slates are vertical, a horizontal boring across the bedding may give a constant stream ; but such a source is a small one. 3. Denudation ; Transportation. Subterranean rivers have sometimes large size, especially in limestone regions, where excavation is easy, as ex- plained on page 130, under Chemical Geology. Those of the caverns of Kentucky and Indiana have their cascades, like ordinary rivers, and may be navigated for long distances. Into such caverns rivers sometimes enter and become "lost rivers;" while from others issue great streams, whose source is unknown. The cave of Adelsberg, 22 miles northeast of Trieste, has its river ; and the Jura Mountains send forth streams to day- light full grown. The work of denudation and transportation is like that above ground, although less supplied with materials for transporta- tion and wear. Subterranean waters do much efficient work in a quiet way by the trans- portation of sand along the course of streamlets that have their outlet at the base of bluffs. The undermining of centuries in this way may make chambers that lead to the sinking of masses of the land, and determine lines of surface drainage. Section illustrating the origin of Artesian wella. 208 DYNAMICAL GEOLOGY. 4. Landslides. Subterranean waters sometimes produce disastrous re- sults by adding their weight to loose or porous deposits and so occasioning landslides. Landslides are of three kinds : (a) The mass of earth on a side-hill, having over its surface, it may be, a growth of forest trees, and, below, beds of gravel and stones, may become so weighted with the waters of a heavy rain, and so loosened below by the same means, as to slide down the slope by gravity. A slide of this kind occurred, during a dark, stormy night, in August, 1826, in the White Mountains, back of the Willey House. It carried rocks, earth, and trees from the heights to the valley, and left a deluge of stones over the country. The frightened Willey family fled from the house, to their destruction. The house remains, as on an island in the rocky stream. (&) A clayey layer, overlaid by other horizontal strata, sometimes becomes so softened by water from springs or rains, that the superincumbent mass, by its weight alone, presses it out laterally, provided its escape is possible, and, sinking down, takes its place. Near Tivoli, on the Hudson River, a subsidence of this kind took place in April, 1862. The land sunk down perpendicularly, leaving a straight wall around the sunken area, 60 or 80 feet in height. An equal area of clay was forced out laterally underneath the shore of the river, forming a point about an eighth of a mile in circuit, projecting into the cove. Part of the surface remained as level as before, with the trees all standing. Three days afterward, the slide extended, partially breaking up the surface of the region which had previously subsided, and making it appear as if an earthquake had passed. The whole area measured 3 or 4 acres. (c) When the rocks are tilted, and form the slope of a mountain, the softening of a clayey or other layer underneath, in the manner just explained, may lead to a slide of the superincumbent beds down the declivity. In 1806, a destructive slide of this kind took place on the Rossberg, near Goldau, in Switzerland, which covered a region several square miles in area with masses of con- glomerate, and overwhelmed a number of villages. The thick outer stratum of the moun- tain moved bodily downward, and finally broke up and covered the country with ruins, while other portions were buried in the half-liquid clay which had underlaid it and was the cause of the catastrophe. Similar subsidences of soil have taken place near Nice, on the Mediterranean. On one occasion, the village of Roccabruna, with its castle, sunk, or rather slid down, with- out destroying or even disturbing the buildings upon the surface. Besides (a) the transfer of rocks and earth, landslides also cause (b) a scratching or planing of slopes, by the moving strata and stones ; (c) the burial of animal and vegetable life; (d) the folding or crumpling of the clayey layer subjected to the pressure, where the effect does not go so far as to produce its extrusion and destruction ; while the beds between which it lies are only slightly compacted or are unaltered; and (e) depressions of the surface which may become lake-basins. Fig. 188 is a reduced view of WATEK AS A MECHANICAL AGENT. 209 a layer thus plicated, from the Quaternary of Booneville, N.Y. Vanuxem illustrates the facts there observed by him, with this and other figures (N. Y. Geological Report), and attributes the plications to lateral pressure while the layer was in a softer state than those contiguous. In parts of the shores of western Patagonia, 18 g where the soil is always wet, the soil-cap is always slipping downward over the basement rock ; and it carries along not only its cover- ing of trees and shrubbery, but also a "moraine profonde" of rocks, stones, tree-trunks, peat and mud, denuding the hills, filling valleys, and feeding the ocean. (R. W. Coppinger, 1881.) Areas on the Falklands, called " stone rivers," , . , . . ._ TT ri _. Plicated clayey layer. Vanuxem. may nave the same origin. (W. Thomson.) Soil-cap movements and land-slips sometimes dam up valleys and make lakes. But loading with waters is only one of the methods of producing such movements. Amount of absorbed water within the earth. The amount of absorbed water in the earth has been increasing from the time of the earth's consoli- dation. The thickening of the supercrust, by the addition of sedimentary strata, has been attended by a continued addition to the amount. Ejected igneous rocks take in water on cooling. Other sources of augmentation are the making of hydrous iron oxides through oxidation, of clays through the decomposition of feldspar, and of gypsum and other hydrous minerals. If the thickness of the supercrust over the continental portion of the globe average 10 miles, and the average volume of moisture in the forma- tions, both metamorphic and unaltered, be 2-5 per cent, the whole amount of water absorbed and confined would be -fa of 10 miles, or about 1300 feet in depth, for the area of the continents. The deposits over the oceanic basins have relatively little thickness. Whatever reasonable allowance be made for them, the whole loss to the ocean waters, in depth, from this source, will not exceed 800 feet. The confined water of the rocks, while a feeble agent of change at the ordinary temperature, is one of immense importance when much heat is present. II. THE OCEAN AS A MECHANICAL AGENT. The working agencies of the ocean of a mechanical kind are, as has been stated, those of (1) the tidal wave ; (2) the wind-made waves and currents ; and (3) earthquake waves. Besides these agencies, the sun's heat, by vary- ing the temperature and density of the water, affects the ocean's movements. In mechanical work, the waters of the ocean have an advantage over fresh waters in being of greater specific gravity by -fa to -fa. They have also the important quality of depositing sediment more rapidly, because less viscous, owing to the saline condition of the waters. A fine sediment, DANA'S MANUAL 14 210 DYNAMICAL GEOLOGY. which takes 10 to 14 days to settle in pure water, settles in 14 to 18 hours in a solution of common salt (W. H. Sidell, 1838). A fine clayey precipitate goes down in a solution of the strength of sea water in 30 minutes, which in pure water would take as many days (W. H. Brewer, 1883). Since the chief part of oceanic work requires the presence of rock-mate- rial, depth of water is a condition of prime importance. It is only within shallow depths that the waters come extensively into working contact with rocks ; only in the shallow belt where water and rocks are together along the emerging line that the greatest amount of force is generated for work. Being at a depth of 500 feet in the ocean is not as complete removal from oceanic forces as being 500 feet above it, but the geological results produced at this and greater depths are relatively small. As explained beyond, there are wide differences between the work of the upper 10 fathoms along shores, and that of the depths from 10 to 100 fathoms ; of greater depths along the sides of the oceanic basin when reached by marine currents ; and of depths from 100 fathoms to abyssal depths, remote essentially from all currents. It is therefore obvious that the era in geological history when the ocean carried on the greatest amount of rock-making was that of general con- tinental submergence at shallow depths, with a scattering of emerged rocky ridges or areas. This was the condition of the earth through the Paleozoic eras ; and, to a large extent, through Mesozoic time. The condition was in striking contrast with the later and present state, in which the continents have only a narrow margin of shallow water. This fact should be kept in mind when comparing ancient geological events with modern. The time of the greatest amount of ocean work was that of the least amount of river work. CHARACTERISTICS OF THE WORKING AGENCIES. 1. The Tidal Wave. The tidal wave moves as a force wave, and has a mean height, along coasts where least influenced by the land, of less than a foot. The height on the projecting capes of continents is 1 to 2 feet, but along intervening coasts commonly from 4 to 12 feet, and in bays and straits, 15 to 18 feet or more. Along the east coast of North America, southern Florida, Cape Hatteras, and Nantucket are the dividing points between a " Southern," "Middle," and "Eastern" Bay (Bache). The height is 1 to 1 feet at southern Florida, 2 at Cape Hatteras, and 1 at southeastern Nantucket ; but in the Southern Bay at Savannah it is 7 feet ; in the Middle Bay, at New York, it is 5 feet ; in the Eastern, at Boston, 10 feet. Up deep bays, when the tide enters between strongly converging coast lines, the wave increases much in height. At the Bay of Fundy, an unusu- ally long wave enters and reaches a height of 40 feet, and even 60 to 70 feet at the highest tides ; the advancing wave is like a moving water-fall . of majestic extent, but without foam. At the entrance to the Bristol Channel, WATER AS A MECHANICAL AGENT. 211 England, the maximum height is 18 feet, and within it, at the mouth of the Severn, 45 to 50 feet. In Long Island Sound (Fig. 189), which is about 100 miles long, the tide outside, at Block Island, is but 2 feet ; but inside, at New London, it is 3 feet ; at the mouth of the Connecticut, 4 ; at New Haven, 6; at Bridgeport, 7; and off Hewlett's Point, near Hell Gate, where it meets the inflowing tide of New York Bay, 7-|- feet. The map shows further, by the cotidal lines over the Sound, that the time of the passage from Block Island to Hewlett's Point is about 4J- hours ; and that, at the fourth hour, it is high tide almost simultaneously along the whole inside coast. The height of the tide is depressed somewhat by high atmospheric pressure, but the amount of depression is not yet pre- cisely ascertained. 189. Long Island Sound, | Long Island, and the Atlantic Border with Depths along Bathymetric ines in fathoms ; Cotidal inea m Long Inland Sound; the under-water Channel of Hudson River, Coast Survey Charts 73JOO When the tide enters straits by two passages, progress in either direction depends on depth and obstructions, and leads to meeting at different heights. At Batscham, in Tong-king, the waves, coming from the China and India seas, meet bringing opposite but nearly equal changes in the water level, and the result is almost no perceptible tide. The tidal wave of New York Bay meets that of the Sound at varying heights, causing violent currents at Hell Gate ; 212 DYNAMICAL GEOLOGY. and at each ebb, on an average, 448,000,000 cubic feet pass from the Sound westward. Again, where the tide up a large river is detained at the head of a gradu- ally contracting estuary by sand-bars with only narrow passages, it some- times moves up the river all at once in one or a few great waves, producing what is called an eager (or bore) ; as at the mouth of the Hoogly (one of the mouths of the Ganges), on the Tsien-Tang in China, and on the Amazon. In the Tsien-Tang, at the equinoxes, the wave moves as a foaming wall of water, 20 feet or more high and four or five miles broad, and thus it passes Hang- Chau-Fu at a rate of 25 miles an hour, dying out about 80 miles above. The change from ebb to flood tide is almost instantaneous. (Macgowan, 1855.) At the large northern mouth of the Amazon, the pororoca, as it is there called, passes up the stream in three or four closely following waves, each 15 to 20 feet high. As soon as the previous tide stops running out, the approaching wave is seen as a white line on the eastern horizon ; onward it comes with rumbling sounds (imitated in the word pororoca) that grow louder and louder ; finally it rushes forward over the top of the long wall, like an endless cataract, in quick pursuit by the other waves ; and continues up the river for 70 or 80 miles, or two thirds of the way to Macapa. (J. C. Branner, 1884.) Rivers with open mouths receive the tidal wave quietly and carry it as far within as high-tide level goes, the movement being communicated to the water of the river, and the salt water following for part of the distance, and ending as an under-current. It extends up the Amazon to Obidos, nearly 500 miles ; up the Hudson to Troy, 150 miles, two waves being in the river .at once; up the Connecticut to Hartford, 50 miles. Rising above the level of the wells along the coast and the outlets of subterranean streams, it raises their waters, so that such wells also have their tides. In seas more or less shut in from the ocean and outside of the general course of the tidal wave, the tides are small. In the Mediterranean, for example, the tide is perceived only at the ends of bays, as at Venice in the Adriatic. In consequence of the tidal movement the sea has its flood-grounds, like rivers ; but the floods occur twice a day, with each recurring tide. At some places in the Pacific, owing to the conjunction of tidal waves, high water occurs uniformly at 12 h., and low at 6 h. This is the case at Tahiti, where the tide has a height of 1 to \\ feet. The author governed himself accordingly in his excursions at low water over the coral reefs. 2. Winds : Wind-made Waves and Currents. As the great currents of the oceans the Atlantic and others are attributed by many to the action of the regular winds, these currents may here come under consideration as well as those made by storm-winds. But the currents made by the storm-winds, that is, the littoral currents and the WATER AS A MECHANICAL AGENT. 213 attendant waves, are the efficient agents, because they act directly against and along the coasts, and have great power. Storm-winds, as stated on page 159, have often a velocity of 60 to 10() miles an hour. They have built up, by drift-sands alone, the east side of the Bermuda reefs to a height exceeding 200 feet, while the regular winds have not raised the side of the coral reef facing them above high-tide level. They have made similar drift-hills on the Bahamas, and over the Florida reefs. Waves rise in long lines transverse to the course of the winds, but with irregularities in the lines, owing to veerings and other variables in the driv- ing agent. Their height depends on the size of the sea, as well as on the winds, and in shallow water on its depth. But every seventh or eighth wave is often a maximum, it being a combination of two, one overtaking another. Waves have at times great height. The highest measured by Scoresby stood 43 feet above the intervening trough, or 21J feet above the mean water-plane or plane of rest. According to results obtained by the United States Hydrographical Department, the storm-waves of the North Atlantic have a maximum height of 44 to 48 feet, but ordinarily a height of 30 feet, and a length of 500 to 600 feet. But the depth of the action of waves is moderate. In a wave, each par- ticle of water moves in a circle about its center of rest, a circle of 21J feet radius in a wave of 43 feet. But these circles at a depth of only one wave-length have a radius 3-^ of that at the surface, and at a depth of two wave-lengths, 3 ^ ; so that if, for the 43-foot waves, the wave-length or the distance between the crest of two consecutive waves is 300 feet, the circle at a depth of one wave-length will have a diameter of ^ of an inch, and at two wave-lengths, y^j- of an inch. Consequently the move- ment of the heaviest waves in the open ocean is exceedingly slight, if appar- ent at all, at a depth of 100 fathoms. This depth is the probable limit of the movement of sand by wave-action, but not the limit of the action of currents. 3. Earthquake Waves. In an earthquake, the movement of the earth may be either (1) a simple vibration of a part of the earth's crust, or (2) a vibration with actual eleva- tion or subsidence. If submarine waves are produced, they have a forward impulse, and, in the second case, an actual forward movement or amplitude equivalent to the amount of change of level ; in each case, therefore, they are translation waves. The velocity of propagation varies as the square root of the depth, the number of miles per hour being 12*2 miles in a depth of 10 feet; 38-7 in that of 100 feet; 122-3 in that of 1000. An earthquake at Concepcion, Chile, set in motion a wave that traversed the ocean to the Society and Navigator Islands, 3000 and 4000 miles distant, and to the Hawaiian Islands, 6000 miles ; and on Hawaii it swept up the coast, tem- porarily deluging the village of Hilo. An earthquake at Arica, and other parts of southern Peru, August 14, 1868, sent a wave across the Pacific, west- 214 DYNAMICAL GEOLOGY. ward to New Zealand and Australia, northwestward to the Hawaiian Islands, northward to the coast of Oregon ; and this was repeated in May, 1877. 4. The Sun's Heat: a Cause of Varying Temperature and Density. Evaporation causes an increase in the proportion of salt in the ocean, or in its salinity, and thereby an increase *in density ; and this is under cer- tain conditions a potent cause of currents. The Mediterranean Sea affords an example. It has been estimated that this sea loses annually 60 per cent of its water by evaporation, and receives, through rivers and precipitation, about 30 per cent ; so that there is a deficit of 30 per cent which is supplied by the Atlantic through the straits of Gibraltar. It is consequently inferred that if the connection with the ocean were cut off, the sea would be reduced to a great basin with two intensely salt "Dead Seas," an eastern and a western. (It has been suggested that this may have been its condition dur- ing or since the Glacial period.) In consequence of this loss by evapora- tion, the water is -^ more saline than that of the Atlantic (page 49). On account of this condition the sea has an inward and outward current at Gib- raltar ; the latter carrying off the denser Mediterranean waters ; the former resupplying the loss resulting from both evaporation and the outflow. It has been calculated that the inflowing current is equivalent to a current eight miles wide, 600 feet deep, moving at the rate of 18*3 miles in 24 hours. The currents being reversed with the tides, this is the balance of the inflow over the outflow in the upper current. (Carpenter, 1872; Buchanan, 1883.) On the varying salinity of sea water, see page 121. MECHANICAL EFFECTS. 1. Tidal Wave and Currents. 1. The tidal inflow. Since the tidal wave becomes a translation wave on soundings, it thereby gains theoretically some power of transportation. But on open coasts the inflowing movement at the rate of a few feet only in six hours is too slow for much efficient work. Its feebleness as a geological agent can be best appreciated during a calm day on the seashore when, although the air and waters are seemingly at rest, the tide is nevertheless rising. The tidal wave in its landward movement follows the deeper parts of the bays and sounds, where friction is least, and with less velocity their coasts. It is therefore weak in sea-border work. This is well shown by the cotidal lines of Long Island Sound on the preceding map as laid down by Schott. These lines reach the coast of the Sound along its western half nearly at the same time. The tide enters the Sound along its bottom, as an " underrun," one and a half hours before the ebb of the surface waters has ceased (E. E. Haskell). The rising tide affords the wind-made waves a chance twice a day to ply their blows against cliffs and beaches at regularly changing heights, and thus WATER AS A MECHANICAL AGENT. 215 promotes abrasion on sea-borders in a way not possible on the shores of lakes. The flow up the coast and the tidal rivers sets back the river waters, gives them increased depth, and floods the tidal flats. Passing up large bays which gradually narrow inward, the mass of water becomes forced to quicker movement or greater height, or both, to keep time with the advance behind ; and in such cases, coasts, against which there is friction, may be worn, and if shallow, some stirring up of the bottom may be produced. And if, further, the waters are held back by obstructing banks until nearly at full tide before they move in, they may rush forward, as in the eager, with greater destruction. When the eager of the Tsien-Tang is approaching Hang-Chau-Fu, the boats along the shore are quickly rowed to the middle of the stream and placed with the bow to the wave ; they rise and fall as it passes, about 20 feet, and in a few minutes are back at their shore traffic, facts evincing that the waters are those of a wave, and not of a current. But along shores that obstruct the movement artificial embankments or dykes are often torn up. The eager or pororoca of the Amazon has the action of an enormous plunging wave. The forest-covered land, as Branner states, is torn up to great depths ; forests are uprooted and swept away, the trees left matted and tangled and twisted together upon the shore, or half buried in the sands, " as if they had been so many strings or bits of paper," and the region inland over which the flood has swept is loaded with the debris. Moreover, new islands of large size and new shoals and bars and channels are left behind it. Branner adds that this is the work of the tidal wave, not of a tidal current. 2. The outflow. By the inflow of the tidal wave a great body of water along a coast is raised some feet above low-tide level, and acquires thereby an amount of energy depending on the height of the tide. The energy is expended during the outflow in abrasion, transportation, deposition, overcom- ing friction, and in other ways ; and sometimes it is utilized for impounding a portion of the water at high tide, and making it turn a water-wheel for a mill or a pump. As has been remarked, it may become an important source of heat to man when coal-beds are burnt out. It is the source of tidal currents. The ebbing waters lie on the bottom of shallow bays and necessarily follow the lowest channels ; and they thus be- come divided into many workers, which may severally abrade or scour the bottom, though generally more or less combined in their work of transporta- tion and deposition. Along the deeper middle portion of Long Island Sound the mean velocity of the outflow is 2-8 feet per second, and of the inflow 3-2 feet (Haskell). The force of the outflowing waters through bays is augmented where rivers add to the depth, and also by the additions to the waters of a bay by storm-winds. The denuding or scouring action of the movement, added to that of the inflow, is manifest not only at harbor entrances, but also over the sea-bottom in its shallower parts. In Long Island Sound wherever there is any narrow- 216 DYNAMICAL GEOLOGY. ing by shoals or islands there is an increase of the depth and velocity, and consequently an increased denuding force. South of Norwalk (long. 73 23' W.), where the breadth is reduced one half by a projecting point of Long Island, the depth at center is increased from 15 to 32 fathoms. Again, south of Stratford (long. 73 6'), there is a shoal, and consequently a deepening to 27i fathoms. Again, to the eastward, south of the mouth of the Connecticut Biver, where the Sound is narrowing toward its obstructed entrance, the depth increases in 5 miles from 12-15 fathoms to 25-29 fathoms ; and then, in 40 miles, nearing the entrance, to 45,50, and 55 fathoms. The accessions of waters from the rivers give some aid in this deepening. Once outside, the depth of the waters diminishes ; but the channel made by the scour may be traced until Block Island is passed ; and the loops just south, of 30, 40, 50 fathoms in the bathymetric lines, suggest that it may extend in a wider form nearly to the 100-fathom line. However this may be, the sea-bottom channel indicated on the map southeastward of New York Bay, while rightly con- sidered the former course of the Hudson River channel during a period of sea-border emergence (D., 1857), probably owes its present depth out to the 40-fathom line, to the combined effects of drifted sands and the scouring action of the ebbing waters (D., 1890). In the discharge of a river into a salt-water bay, the fresh waters flow over the salt ; and in some cases so little commingling takes place that shallow streams, carrying little detritus, leave uninjured the marine life of the bottom. 3. Deposition usually takes place inside of bays or estuaries wherever there is an eddying of the waters or diminished velocity, as well as over tidal flats. There is deposition also at the entrance of the bay, when the tidal waters meet the sea outside, and spread and rapidly lose velocity : and at the ebb, this area of deposition may become prolonged into and up the bay. But part of the inside deposits are scoured away with the next outflow. Deposition off shore of the detritus made by the grinding of beach sands is only, to a very small degree, a result of tidal action. It is chiefly wave and current work. The making of ripples over sand-flats and shallow sea- bottoms is partly a result of the gentle tidal inflow or outflow ; but it is also the work of wave-and-current movements. The height of the tide fixes an upper limit to tidal flats and sand-bars in estuaries and bays by the limit it gives to deposition. But the seashore flats along some rocky shores are a result simply of the shearing action of the passing waves. 2. Wind-made Waves and Currents. 1. Their power. The waves that come in from the ocean and break heavily on the beaches and against the cliffs, are wind-made waves ; and those of great force are made and propelled by storm-winds. Their progress is land- ward ; and the break at summit takes place when the depth of water below the trough equals about one half the height of the wave. The wave ad- WATER AS A MECHANICAL AGENT. 217 vances, and rises in consequence of the diminishing depth. At the break- ing, or the collapse, of the wave, the waters are thrown forward, and dash, for the most part, up the shore, while the trough part of the wave flows off as the " undertow,' 7 followed down the beach by the returning water of the collapsed wave. Some features of the movement are well illustrated in Hawaiian surf-riding. The Hawaiian, swimming out with his plank, plunges beneath the first billow and rises beyond it ; then dives beneath another, and another, until he has passed one of the great billows. This he mounts, and, if rightly placed on it, rides to the beach with great speed. Should his plank not keep the right angle on the crest of the billow, the surf of the following wave will overtake him ; but this he would avoid by diving beneath it and swimming out farther for a fresh start. The work done by the wave-and-current agency includes abrasion of the most violent kind, as well as the gentlest, and transportation and deposition as extensive as coast lines and shallow sea-borders or seas. It is the agency that preserves to the continents the detritus of the discharging rivers, inas- much as waves work landward ; yet it has aid in this in the fact that sedi- ment drops in salt water in one fifteenth of the time required in fresh. On the borders of the Gulf of Mexico, according to A. Agassiz, river sediments do not extend out beyond the 100-fathom line, for at this depth there is always the usual sea-bottom life. Along the Atlantic border there are sedi- ments in deeper water, but this is because icebergs or icefloes have dropped there loads of gravel and sand. This agency also makes impossible the transportation of material from one continental land to another. If the fabled Atlantis were at the surface over the Dolphin shoal (page 19), the waves and currents would work about it and for it, and allow of no contributions to any outside land, and least of all to America the con- tinent supposed to have needed help. 2. Work of denudation. The waves bring to bear the violence of a cataract upon whatever is within their reach, a cataract that girts all the continents and oceanic islands. In stormy seas, they have the force of a Niagara, but with far greater effects ; for Niagara falls into a watery abyss, while, in the case of the waves, the rocks are made bare anew for each successive plunge. They work by impact, and with enormous force. They have also great abrading power added to impact, through the load of debris they take up and transport. Stevenson, in his experiments at Skerryvore (west of Scot- land), found the average force of the waves for the five summer months to be 611 pounds per square foot, and for the six winter months, 2086 pounds. He mentions that the Bell Rock Lighthouse, 112 feet high, is sometimes buried in spray from ground-swells when there is no wind, and that on No- vember 20, 1827, the spray was thrown to a height of 117 feet, equivalent to a pressure of nearly three tons per square foot. During a westerly gale in March, 1845, his dynamometer registered a pressure of 6083 pounds per square foot, which gives for the velocity per second, by the formula, *. (P being /6083 218 DYNAMICAL GEOLOGY. the pressure in pounds and 64 the weight of a cubic foot of sea water), x 32 ' 2 = 55-32 feet. The hydrostatic pressure due to a wave 20 feet 64 high is over (1280 Ibs.) half a ton to the square foot; the rest of the force comes from its velocity. Mr. Stevenson states that on one of the Hebrides a mass of rock of about 42 tons weight was gradually moved in a storm five feet ; with each incoming wave it was made to lean landward, and the back run uplifted it with a jerk, leaving it with little water about it. It is reported that at Unst, one of the Shetlands, walls were overthrown and a door broken open at a height of 196 feet above sea level. Geikie attrib- utes part of the effects of the impact to the compression of the air of cavities by the striking waters, and then its sudden expansion, with tearing effects ; and also to the rarefaction of air caused by the sudden withdrawal of the waters after a broad stroke, this leading to displacement of blocks or masses. He mentions the case of a securely fastened door at the Eddystone Light- house forced outward by the stroke of the outside surface by a wave ; and suggests that the principle may account for stones being started from their places in a solidly built stone wall. The water driven into crevices has great rending force. The heaviest waves exert little force against rocky cliffs, or the sea-bot- tom, below a depth of 15 or 20 feet. Their abrading action cannot, therefore, shear off cliffs, or wear away an island in the ocean, to a lower level. This principle is recognized in making defense walls of masonry against breakers by planting the wall out where the depth is 15 to 20 feet. Waves, as they march up a shore, sometimes throw stones to great heights. Geikie cites the report that during northwesterly gales the windows of the Dunnet Head Lighthouse, at the northern extremity of Scotland, 300 feet above high water, are sometimes broken by stones from the enormous breakers. In view of the force at work it is not surprising that, in regions like Cape Horn, or the coast of Scotland, where storms are common, cliffs should under- go constant degradation, be fronted by lofty castellated and needle-shaped rocks, and that the land should be pierced at times for blow-holes where layers of easy removal, or dikes or veins, face the breakers. The following figures from a memoir by Professor Shaler illustrate well some of the results. They represent scenes on the coast of Maine, near Mount Desert. Fig. 190 shows a detached rock on its march seaward; and Fig. 191 a pile of displaced masses as it was left at the base of a cliff before an ele- vation of the coast of 220 feet. All the processes of rock-destruction help in this work of degradation, the opening of rifts by intruding moisture, or by oxidation, or by change of temperature, or by growing plants and the decay of weak portions of the rocks. Under the incessant beating, every stroke tends to slip out of place masses, however large, that rest on a sur- face not perfectly horizontal. WATER AS A MECHANICAL AGENT. 219 The cliffs of Norfolk and Suffolk, England, afford an example of seashore encroachment that has long been under observation as the country is one of houses and cultivated fields. Lyell states that in 1805, when an inn at Sherringham was built, it was 50 yards from the sea, and it was computed that it would require 70 years for the sea to reach the spot the mean loss of land having been calculated, from former experience, to be somewhat less than one yard annually. But it was not considered that the slope of the ground was from the sea. Between the years 1824 and 1829, 17 yards were swept away, bringing the waters to the foot of the garden ; and in 1829 190. Rock detached by wave-action, Otter Creek, Mount Desert, Me. Shaler, '* there was depth enough for a frigate, 20 feet, at a spot where a cliff of 50 feet stood 48 years before. Farther to the south, the ancient villages of Shipden, Wimp well, and Eccles have disappeared. This encroachment of the sea has been going on from time immemorial. 3. Limit of wave-denudation ; Planation. Besides battering and degrad- 220 DYNAMICAL GEOLOGY. ing cliffs, wave-action makes shore-platforms, by shearing away the rocks of coasts down to a horizontal surface near low-tide level, and in the process cliffs are undermined and set back. These effects are produced where the rocks are of moderate firmness, where they are not too hard to yield rather easily to the waves, and not so weak as to be torn up by the gentler attack of low-tide movements. As the tide rises, the earlier waters quietly cover 191. Rocks detached by wave-action, Mount Desert, on an old beach at a height above the sea of 220 feet. Shaler, '89. the rocks. Then the waves move in ; but the rocks below are under protec- tion, and only those of the cliff or wall take the force of the blow. There is hence, in such cases, a level of no wear near low-tide level. The level of greatest wear is that of the stroke of the breaker at or above high tide. WATER AS A MECHANICAL AGENT. 221 This feature of wave-action, and the reality of a level of little or no wear above low tide, are well illustrated by facts observed by the author in 1840 on the coasts of Australia and New Zealand. ^ 2 * In Fig. 192 (representing the south cape at the en- trance to the harbor of Port Jackson, New South Wales), the horizontal strata mak- ing the base of the cliff, cut crosswise by joints, extend out in a platform a hundred yards wide. The tide rises and covers the platform ; and the waves, unable to reach Cliffs at entrance to Port Jackson, New South Wales, Australia. D., Note-book, '40. its rocks to tear them up, because of the protection thus afforded, drive on to batter the lower part of the cliff. The strata belong to the Sydney sandstone formation. At the Bay of Islands, New Zealand, there is a similar seashore platform, as illustrated in Fig. 193, represent- 193. ing an island in the bay called " The Old Hat." The rock here is a rather firm argillaceous sandstone without bedding. By elevation such shore-platforms become sea-border terraces. The Old Hat," New Zealand. D. '40. Another region of such shore-platforms is the Island of Anticosti in the Gulf of St. Lawrence. They have a width there of 100 to 150 yards (Verrill). The broad seashore platform of coral islands or atolls has the same origin (page 146). It occurs on both their leeward and windward sides, and varies little in surface from horizontally. Coral-made limestone, like other kinds, is of easy abrasion. As here shown, there is a limit to wave-abrasion. Under the circum- stances stated, it does not cut much below low-tide level Even an atoll stands its ground and grows in size in spite of the waves of a Pacific. Much less can wave action cut valleys into the land. Its province is to batter down cliffs, wear off headlands, and fill up bays. The largest blocks that are raised and carried up seashore are those that are forced along by earthquake ivaves. These waves commence their tearing work at depths that at other times are under the protection of the waters, and the waters, which had retreated from the shore to make the waves, advance to an unwonted height, and make deposits of what they have gath- ered at varying distances inland, according to their gravity, besides devastat- ing the country they cover. But the depth of their action probably does not exceed 30 feet. A ship afloat is -easily moved landward, more easily 222 DYNAMICAL GEOLOGY. than blocks of rock are torn from submerged strata. The earthquake of 1746, on the coast of Peru, carried a frigate several miles inland, besides deluging the seaport Callao, and the city of Lima seven miles distant. The following figures represent masses of coral limestone torn off from the margin of an atoll and thrown on the shore-platform. That of Fig. 194, was 10 x 6 x 6 feet in its dimensions, and that of Fig. 195 seven feet high and six 104. 195. Blocks on the shore-platform of atolls in the Paumotu Archipelago. D. '49. broad. The latter is attached solidly to the reef-rock, and is half cut through by wave action. Another mass on the shore-platform had a length of 15 feet. 4. Transportation and deposition; the making of beaches. Waves, as they rise on a shelving coast, take up and bear along detritus of all degrees of coarseness according to the velocity, and throw or wash it up the shore. Grinding work or corrosion is also ever going on. By such means they give the beach its material, and through the return of the waters, by which much of the finer debris is restored to the sea, its angle of slope. The materials are derived from the wear of cliffs and ledges above the beach; from the loose material of the bottom; from any corals and shells and other organic objects living in the waters ; and from the contribu- tions of marine currents as well as those of rivers whatever is at hand being used. The transported materials may be gathered from depths of 30 feet or more. In regions of high tides and stormy seas, the great, rapidly driven waves, as they move up the coast, may pick up large stones or produce them out of the rocks, and make stony beaches, or they may make a place too rough for a beach. But with lower tides, and away from the rocks, the beaches consist mostly of sand and gravel. Nine tenths of all the beaches between Florida and Cape Cod are sand-made. The slope of the beaches varies much in angle. It is 15 to 18 along the coasts of stormy seas and high tides, 7 to 10 along those of low tides, and 3 and less in sheltered bays. Deposition by the return-flow waters gives this part of the beach a straticulate structure parallel to the inclined surface (page 93). Since the waves go up and down the beach twice in each 24 hours, and gradually become stronger in flow and plunge as the tide rises, the beach is made to consist of : (1) The summit ground, of uneven surface. This is the receiving place for the coarser material, including stones, shells, etc., and also WATER AS A MECHANICAL AGENT. 223 for long lines of seaweeds, which the wash of the waters carries up the beach and has to leave because the sands of the upper and drier part take most of the waters off by absorption. Here and just below are often found accumu- lations of magnetic iron sand and garnet sand, which the return-flow was not strong enough to carry back down the beach with the other lighter sands. (See page 170.) (2) The beach-slope, the outer surface of the beach-formation, the stratification being parallel to it. When sand-made, its surface is marked with faint channelings of rills from the return-flow, and more faintly with wave-like outlines of the upward wash. (3) The under-wetter slope the continuation of the beach-slope downward beneath the water made by the undertow and perhaps coarser in material than the part above. It is the place for boring Mollusks, Sea-worms, and Crustaceans. Stones and coarse shells that may be dropped by the flinging breakers on the beach-slope are pretty sure to be carried back by the return-flow for another chance of trans- port, because the plane of rest is underneath them and not through their centers of gravity ; and for the same reason the stones of experimenters on beach-action usually go the unexpected way seaward. The grinding carried on over the beach reduces the sand to finer sand, and especially the grains of feldspar and of all minerals softer than quartz. The undertow carries these seaward, where the current distributes them over the shallow bottom. In this way deposits of fine earth, clay, or mud are forming near those of coarse sand or gravel. Tidal flats of mud or sand in estuaries, when lying exposed above low water, are likely to receive ripple- marks, foot-prints of passing animals, raindrop prints, mud-cracks, and to secure, when the tide turns, their burial beneath other sands and thus their preservation. Under the tearing action of the heavier seas, the summit- ground may be put temporarily into the beach-slope, or large portions of a beach may be torn away and reconstructed; and, since the volume of the return-flow would be at the same time augmented, the beach may become temporarily steeper and coarser. Along most windy shores it requires only one of the extraordinary storms that come at long intervals to destroy much of the work of a century. 5. Extension of beaches into points or spits, and barriers. A beach is, in the long run, essentially permanent in form and structure, unless a coast is undergoing change in level or in other respects. But in regions of frequent storms, the storm-made waves and currents give the sands a set or drift to leeward. When, in this way, the line of a beach reaches in its leeward extension a shallow bay, the drift of sands, still continuing, will build out a point where the current loses velocity against the stiller water of the bay ; or, if the water is not too deep, it will extend a barrier of beach-sand across the bay, cutting off an inner shallow portion from the ocean, leaving only a single oblique entrance, which the tides had kept open. By such means the south side of Long Island, and a large part of the Atlantic coast south of New York, has been supplied with its beach-sand barriers, and also, inside of the barriers, with a long range of sounds. 224 DYNAMICAL GEOLOGY. The map, page 211, affords illustrations of these barriers. Montauk Point has its "beach, and also its bluffs of sand and coarse gravel. Westward, the beach is continued on in a series of barriers, outside of a series of shallow bays, which extend all the way to Coney Island and New York Bay. The barrier is seldom over 600 yards in width, and is almost wholly bare, yet has stumps at places on the inner side. Moreover, the westward drift of the sands has shallowed the waters south of the western part of Long Island. The zigzags here in the 10- fathom bathymetric line show the direction of the wave-and-current movement. Part of the drifted sands of these beaches were supplied from the bluffs to the east- ward, but part are the gatherings of the waves from the sea-bottom below the beach and barrier, and a small part are from the feeble streams of southern Long Island. Along the New Jersey coast and farther south the beaches are usually half a mile to a mile in breadth, and many have an inner forest-covered belt. Sandy Hook 5 miles in length owes its existence to the drifting of the sands, and an accompanying inside current, continued through both the ebb and flow 196. of the tide, as long since explained by Bache. The drift of the Atlantic coast is here carried to the very margin of the deepest ship channel out of New York Bay. The hook-like shape of the extremity may be due to drift in the Long Island direction where that of the New Jersey direction is forced to stop. Fig. 196 is a map of the coast-region either side of Cape Hatteras (H). Along the coast south of New York the rivers carry out a large amount of detritus, which is widely distributed, but the coarser is gathered up by the waves to make the barriers. The position of the cape was probably determined by a cape of rocky ridges which is now submerged. Off the great Middle Bay of the Atlantic coast the storm-winds have their greatest velocity when blowing from the eastward as they do at the Bermudas ; and hence the course of the wave-and-current movement is toward New York Bay, both along southern Long Island westward and from Cape Hatteras northward. South of Cape Hatteras (H) the drifting is, for a similar reason, southwestward. oast-region of North Carolina; CK, Curri- tuck Inlet (to Currituck Sound) ; N, New Inlet; H, Cape Hatteras ; O, Ocracock Inlet; C, Cove Inlet; L, Cape Lookout. Examples of remarkable driftings of beach materials along the Atlantic coast are on record. A vessel, the " Sylph," was wrecked in 1814-1815 on the south side of Long Island, and materials from the wreck were drifted westward beyond Fire Island ; and 7 years afterward her rudder was found 20 miles west of where she was lost. In another case, coal from the cargo of a vessel wrecked on the south side of Nantucket was carried eastward and then northward, and the keeper of the lighthouse of the north cape, called Great Point, supplied himself from it with fuel for the winter ; and brick from another WATER AS A MECHANICAL AGENT. 225 vessel pursued the same course. Again, an anchor with 10 fathoms of chain attached, from a brig of 200 tons wrecked on Cape Cod near Truro, was drifted a mile and a half to the north in three weeks. These facts are from papers by Lieutenant C. H. Davis (1849, 1851). Such transportation is beyond the power of any currents ; it is the work of the dashing, lifting, and propelling waves. In the following example, the change of position 197. is connected with a change in the seasons. J. D. Hague states that at Baker Island (of coral), in the Pacific (0 15' X., 176 22' W.), this fact is well ex- hibited. In Fig. 197, I, I, I is the southwest point of the island, and R, R, R, the outline of the coral-reef platform, mostly a little above low-tide level ; its width, cd, 100 yards. In the summer season, when the wind is from the southeast, the beach has the outline s, s, s ; during the winter months, when the wind is northeast, the material is transferred around the point, and has the position w, w, to, having a width at ab of 200 feet. A vessel wrecked in sum- mer, and stranded at V, was transferred to V in the course of the month of November. (J. D. Hague, '62.) 6. Sand-bars at the entrances of harbors or mouths of tidal rivers. The material of the sand-bars which obstruct the entrances of harbors has two main sources : an inner, and an outer ; the former fluvial, the latter the wave- and-current driftings of the coast, which contribute so largely to sand-barriers. The positions of the bars depend much on the strength of the river current ; but also on the direction, form, and supplies of the wave-and-current move- ment produced by the storm-winds. A small stream is often blocked entirely by a sand-bar across its mouths, so that the waters reach the ocean only by percolation through the beach. But large streams make distant sand-reefs or barriers through the aid of the outflow, and keep open channels even in the face of the ocean. The depth of water over the sand-bars at the mouth of a large river or bay is, in great part, only 3 to 10 feet : a remarkable fact, considering the opposing forces at work the tidal outflow and inflow, and the plunge of the storm-made waves over the mobile sands. The sands lie along the area of rest between the contesting movements. New York Bay (map, page 211) affords an example. The contributions of river sediment come from the Hudson River and from small New Jersey rivers ; and the Hudson is mod- erate in its supplies, considering its length and size, because it has almost no tributaries for 60 miles, and small ones for 100 miles, owing to the westward dip of the Catskill strata and the barrier of the Palisades in the southern part. The wave-and-current supplies come from the direction of the Long Island and the New Jersey coasts ; for New York Bay is exceptional in lying to the leeward of both coasts. Under these circumstances, Sandy Hook, the sand-bars, and the barriers of the Long Island coast adjoining, have been accumulated. The outlining of the bars, and the positions of the three channels through them, are mainly due to the tidal outflow, which DANA'S MANUAL, 15 226 DYNAMICAL GEOLOGY. includes, besides the tidal waters of the bay and river, the river waters of the Hudson and of the New Jersey streams, with the important addition of the high-tide overflow from Long Island Sound ; and the southern channel into the bay is the deepest, apparently because the New Jersey streams empty into the lower bay nearly abreast of this entrance. Large tidal grounds about a harbor are more essential even than a great river for the best conditions of harbor entrances ; and any encroachment on the limits in New York Bay is carefully guarded against. The depth over the surface of the bars is mostly between 3 and 10 feet. 198. 199. ' ^'^M-'^H^v J/^/l ^-x^?* s (Qc$\ $&<** 10 16 C'4o so 3U * 15 M ' 25 21 21 21 21. 24 22 g X ^42 " 31 ?I "^ ^ " "H /* 1 '//IS 13 L.12 8 } i y/fc w v^ ^7t-?^;S 7 V\iB Mouth of Connecticut. Harbor of New Haven. Over the bars at the mouth of the Columbia Kiver, Oregon, occurs the same small depth. A vessel ran aground on the outer bar on July 18, 1841, and, after passing a night of calm weather, but of heavy and disastrous toss- ings as the waves of the Pacific rolled in during the progress of the rising tide, lay quiet at daybreak when the tide was out, fixed in the sands, with a belt of dry sand around her. The next day, she was an abandoned wreck. (D., Notebook, 1841.) The mouths of the Connecticut and Housatonic rivers, and New Haven Harbor, whose positions are shown on the map on page 211, afford excellent illustrations of this subject. The depths in the figures are in feet ; the lines mark depths of 6, 12, 18, and 24 feet. The mouth and sand-bars of the Connecticut Kiver are represented in Fig. 198. The river is the largest of New England, and supplies abundant water and much sediment WATER AS A MECHANICAL AGENT. 227 200. v^/liT \,-'A/ 24 28 "JLJLJL- 3 JHQ,.;

Quartz vein, Cheshire, Conn. D. Banded vein, at Godolphin Bridge, Cornwall. De la B. But granitic veins are sometimes banded, as in Fig. 305, in which 1, 3, and 6 are bands of quartz ; 2 and 4, bands having the structure of gneissoid granite, and 5 that of gneiss. Fig. 306 contains a two-banded vein of quartz. It illustrates the usual mode of origin of bands, showing that they are layers made by deposition against the two walls. It is also a vein of copper ore, the ore lying in the wider open portions of the vein. Figs. 307-309 represent otfyer banded veins, having the bands in two HEAT VEINS. 383 or more sets. Fig. 307 appears as if made up of two veins side by side, abcb one, and d another; two bands b are agate bands (uncrystallized quartz), and at c are two bands of crystallized quartz. The two sides of the fissure received simultaneously the deposition of agate, and then, over this, the layer of quartz in crystals. If a band or string of ore had been deposited between the two of quartz, as is common, this would have made it an ore-vein. But in the 309 b b d d Compound veins from Cornwall. De la B. figure, the large band d is ore, copper ore ; and to make it, the fissure was reopened along the wall to the left, and the ore introduced without any " gangue " material. Fig. 308 represents a triple vein, abba one, c a second, and dd the third ; and Fig. 309, a sextuple vein, or one that was opened six times for new vein-making. Each of the six parts is called a comb in miners' language. In one great vein, opened at Freiburg, the layer consisted of blende (ZnS), quartz, fluorite (CaF), pyrite, galena, barite, calcite, each two or three times repeated, the layers nearly corresponding on either side of the middle seam. The ore of veins occurs in one or several of the bands ; or is gathered along the center ; or collected in the broader portions or swellings of a vein, making nests ; or distributed through the gangue. Most quartz veins cutting through crystalline rocks are actually simple, though begun in each case by deposition against the walls. Gold-bearing veins are commonly ordinary quartz veins, but the gold is usually in minute, invisible scales through the quartz, though occasionally in threads of crystals, and "nuggets " or larger masses. In the case of the gold-bearing quartz, crushing, and then either washing or amalgamation, are required to obtain the gold. Gold-bearing quartz veins contain also more or less pyrite in which gold is often present profitably, and also often galena (PbS) and sphalerite or blende (ZnS). A region of chloritic or hydromica schist having interl animating and intersecting veins of quartz, in which occur some pyrite and galena, is almost always a gold region. The banded structure of many veins is one of the points in which veins differ from dikes. But they are often like dikes in having contact minerals in the walls of the veins, due to the same process which filled the vein. 334 DYNAMICAL GEOLOGY. 4. Making of Veins. In the making of veins, the material has usually been deposited against the walls ; and from the wall layer thus made there has been a thickening to the center. The work is, therefore, centripetal. The materials have been introduced either (1) from above, or (2) lat- erally, from the rocks adjoining some part of the fissure, or (3) from below. The filling of superficial cracks is done usually without aid from heat. But in most vein-making, heat has been required. 1. Superficial Vein-making, not requiring Heat. The shallow cracks of rocks, like those of mud-beds, and any cavities opening upward, may take in calcite, silica, or other ingredients from cold solutions, and make superficial veins. The process is mere deposition, and commonly without heat. In a similar manner cavities and caves have sometimes become filled. Or when a bed is slightly calcareous, permeating waters have taken into solu- tion some of the calcareous portion (calcite), and if cracks or fissures existed, have filled them with calcite. Siliceous solutions, in like manner, may make veins of quartz. So any solution made by oxidations or other means, may carry material into cracks and produce veins or veinlets. 2. Vein-making requiring Heat. Vein-making requiring heat is carried on in regions of hot springs in a superficial way. But in general, the process has gone forward in fissures permeating hot rocks, and the work of filling has been dependent on the heat and moisture the rocks afforded. These fissures, in the case of the majority of veins, have not descended to regions of fusion ; while in the case of other veins of even greater importance, as regards ore-production, they have reached fusion-depths and have let up melted rock. The veins of the first of these kinds are especially common in Archaean rocks ; while those of the second belong mostly to later time. Superficial Vein-making. Superficial vein-making is in progress at hot springs in Nevada, Cali- fornia, and elsewhere. Such springs, making solfatara areas, are usually in regions of former eruptions. In Nevada, at Steamboat Springs, according to J. Arthur Phillips (1879), fissures are being lined with a siliceous incrustation, while at the same time steam and gases, with boiling water, are escaping; and "they have been subjected to a series of repeated widenings," and become lined, to a thick- ness of several feet, with silica, which is in bands, amorphous and crystalline alternating, and contains some hematite, pyrite, and chalcopyrite. Accord- ing to Mr. Laur (1863), the silica of these fissures contains also traces of gold ; so that the facts exemplify, as he states, the essential points in the origin of auriferous quartz-veins. This view was presented by B. Silliman and W. P. Blake, in 1864, with reference to the banded quartz-veins (gold- bearing) of Bodie Mountain, north of Mono Lake, which are contact veins intersecting porphyry. At Clear or Borax Lake, as observed by Mr. Phillips, HEAT VEINS. 385 the siliceous deposits frequently contain pyrite and cinnabar (HgS) and the sulphur bank, which has there been formed through the heated vapors, has been worked as a mercury mine. J. D. Whitney described in 1865 a specimen of gold in cinnabar which was supposed to have come from near " Sulphur Springs," four miles south of Bear Valley, between Clear Lake and Colusa; and Mr. M. Atwood removed doubt as to the source of the specimen by rinding in a fissure at the place mentioned (as reported by Mr. Phillips) cinnabar overlaid by a brilliant deposit of metallic gold. Similar facts are reported by Le Conte (1882, 1883), from the Clear Lake region and Steamboat Springs. In the former, at "Sulphur Bank," occurs sulphur with cinnabar below (which is now worked), and also pyrite and gelatinous silica. Le Conte explains the occurrence of cinnabar (HgS) on the ground of its solubility in a hot solution of sodium sulphide (Na. 2 S), this alkaline sulphide resulting from the action of the sulphur gas on the rocks which contain a soda-lime feldspar, and its subsequent deposition. (For Le Conte on Vein-making, see Am. Jour. *Sc., 1882, 1883.) Becker sustains, by experiments (1887), the view that the metallic sulphides (HgS, FeS 2 , ZnS, and less easily Cu 2 S) are soluble in solutions of alkaline sulphides, and that they pass in vapors to be deposited in the veinlets and fissures of the rocks above. He observes that the Steamboat Springs are now depositing gold ; that gold is dissolved by a hot solu- tion of Na 2 S, and that 843 parts of a cold solution of Na 2 S will dissolve one part of gold. Deposition of the sulphides is occasioned by cooling ; by contact with acid waters these, according to Le Conte, descending from the surface where some of the sulphur in the gases makes sulphuric acid and aluminum sulphate ; and also by dilution. Becker pub- lished in 1888 a full report on the quicksilver mines of California. The following facts illustrate further mineral transformations. Daubree found, in the thermal waters at Bour- bonne-les-Bains, in the bottom of a part of which, in Roman times, bronze, silver, and gold coins had become buried, the following mineral species, derived from the alteration of the metal of the first two of these kinds of coins through the agency of the mineral waters, their temperature 140 F. : the copper ores, chalcocite (Cu 2 S), chalcopyrite (CuFeS 2 ), bornite (Cu 3 FeS 3 ), tetrahedrite, atacamite, cuprite (Cu 2 0), chrysocolla, native copper; the lead ores, cerussite (PbO.CO 2 ), anglesite (PbO.SO 3 ), galena (PbS), phosgenite, and pyrite. The bronze was found to consist of copper, tin, and lead, or of copper and zinc, with a trace of iron. The waters afforded, on analysis, chlorides and sulphates of the alkalies (Na 2 , K 2 , Ca, Mg), with bromides and carbonates of Ca and Fe, an alkaline silicate, with traces of arsenic, manganese, iodine, boron, lithium, strontium, caesium, rubidium, and, in exhalations, some H 2 S, N, and O. Similar results were observed by Daubree at the warm springs of Plombieres, Department of the Vosges. Veins made by heat in the Earth's Crust, without aid from deep-seated Igneous Ejections. The crustal heat may be that of the earth's crust either during, or not during, an epoch of metamorphism. Under this head are included most of the great and small granite veins of the world, the auriferous (gold-bearing) quartz veins, and all the common veins of metamorphic rocks. They some- times intersect the foliation, but very often follow it. Their formation was, in general, part of the results of metamorphic heat and conditions ; and the movements attending mountain -making, which produced the metamorphic 336 DYNAMICAL GEOLOGY. heat, were the source of the larger part of the fissures, and the origin of their great diversity in form and positions. The heat varied, therefore, from 212 F. and below, to, in extreme cases, the temperature nearly of fusion ; and it slowly declined as the epoch of metamorphism closed, thus making the same region to pass through conditions of high-grade heat and low-grade heat, and, therefore, through conditions for different sorts of veins. All the transfer and transformation processes through superheated steam engaged in metamorphism were at work in vein-making with like efficiency those of low heat for filling fissures with quartz, and those of higher for making feldspathic or coarse granitic veins, and other kinds. Moreover, the heat so derived continued long, and disappeared with extreme slowness ; so that the filling of veins was usually slow, and the crystalliza- tions going on had almost indefinite time for growing, and generally became coarse. The gigantic crystals of beryl, mica, and other species mentioned on page 331 were thus made. With the heat so widely diffused, it was not necessary that the opened spaces for veins should be continuous. An interrupted series of openings in the upturned strata, as well as the spaces between the leaves of slates and the thinner schists, would have become as readily filled by materials supplied from the rocks, as they would if they had been united along continuous fissures. The hot-vapor solutions, everywhere at work, would have varied their results according to the temperature, the moisture, and the kinds and con- tents of adjoining rocks. If the fissures penetrated rocks having veins or deposits of ore, or sparsely disseminated ores, the ores would be as readily transferred to the veins as the stony minerals ; and the hot vapors, widely distributed, might gather them in from a wide region either side of the fissure, whether at its lowest or highest depths. The vapors, being under great pressure, would find the fissures escape-ways, and the transfer of material would therefore begin as soon as they were opened. Veins of lead ore (galena), copper ores, tin ore, and other kinds are common in the same rocks that elsewhere have their granite veins. Moreover, veins would be likely to contain ores at their intersections with some of the rocks they cross when not at other intersections. As gold occurs commonly in quartz veins, and in those of the feebly crystalline schists, as chlorite schist and hydromica schist, no great amount of heat was required for their formation, and the rocks near by or below must have afforded the gold. Igneous rocks often have fissures intersecting them (due to contraction on cooling, or to subterranean action) and cavities (amygdaloidal) within them, that were filled, in vein-like style, from materials brought in laterally, and mostly while the rock was slowly cooling, as explained on page 298. The permeating hot moisture takes silica, alumina, soda, and lime from the feldspar of the rock, and makes zeolites (hydrous silicates, related to the feldspar) in the fissures and cavities ; and takes silica, lime, magnesia, and iron from the pyroxene to make, with some alumina, the dark green chlorite ; and sets free the excess of silica for making quartz crystals. HEAT \ 7 EINS. 337 The process decomposes the walls of the fissures or cavities to make the filling materials, the walls showing it by their decayed condition. The lateral source may be within an inch or a few inches of the place of deposition ; and still it well illustrates much of vein-making. Bitumen or mineral oil may also be taken in from carbonaceous shales, and deposited in the amygdaloidal cavities and fissures ; and to its presence J. Lawrence Smith attributed the reduction of the magnetite in igneous rocks to grains of native iron, and even the production of the great masses of native iron brought to the surface by basaltic ejections in Greenland. The term vesicle, as applied to a vapor-blown cavity in an igneous rock, has been put into Greek form in the word lithophysa (stone-bubble) by Kichthofen (1860), and applied especially to peculiar chambered cavities common in obsidian, its variety, lithoidyte, and in rhyolyte. They occur in great perfection, as flattened spheroids, in the region of the Obsidian Cliff, Yellowstone Park (Fig. 279, page 306). The following figures are from 310. 311. 313. Lithophysae of the Obsidian Cliff. Iddings. a memoir by J. P. Iddings (1888). Three of the lithophysas are shown, of natural size, in Fig. 310, and three others in section in Figs. 311, 312, 313. The rock containing the lithophysse commonly consists of alternating solid DANA'S MANUAL 22 338 DYNAMICAL GEOLOGY. and spongy layers as represented in Fig. 313, and the thin harder bands in this lamination or straticulation are persistent throughout the lithophysae ; as the figure shows they were sometimes arched in the making of the cavities, while often, on the other hand, they prevented the cavity from completing a circular form. The concentric partitions are fragile and consist mostly of minute crystals of quartz, feldspar, and tridymite ; and sometimes topaz and garnets are in the cavities. Richthofen regarded the lithophysse as made by expanding steam, like vesicles in ordinary lava, and the concentric partitions as having been thrown off in the progress of the expansion, and hence the name. Mr. Iddings points out close relation between the lithophysse and the associated radiate spherulites, and doubts the vesicular mode of origin. The following is a possible explanation. If the cavity made by vesiculation became at first filled with an aqaeo-igneous or jelly-like solution of the rock, the concentric shells may be a centripetal result, due to progress in cooling and loss of moisture from the outside. The process would first produce a deposition of crystals over the confines or wall of the cavity, and thus deprive the inside solution, adjoining this wall, of part of its mineral material ; then, the succession of shells might form inside in a manner analogous to that given for concentric rings on page 130. Johnston Lavis regards lithophysse as concretions growing radiately outward, and refers the spaces between the concentric shells to the liberation of vapor from moisture contained in the glass, this liberation taking place as the glass becomes changed to feldspar in solidification. Whitman Cross, who adopts the vesiculation theory, found beautiful but minute crystals of topaz and garnets in lithophysse of the rhyolyte, of Nathrop, Col. (1884, 1886). Iddings and S. L. Penfield have described (1885) yellow crystals of fayalite from those of the black obsidian at Yellowstone Park. Utah rhyolyte also has afforded topazes. Veins made by the aid of deep-seated Igneous Ejections. For the formation of veins through the heat of igneous ejections, the earth's crustal heat has been the agent, aided possibly by heat from local crushing and friction. The fissures at great depths may have had the heat required, without addition from mountain-making movements. The general steps of progress that is, the methods of transfer and formation of mineral material by heated vapors are the same that have been described. Fissures descending to regions of fusion are necessarily deep fissures, and for this reason the veins that have been made in connection with them include the richest of ore-bearing veins. The deep fissures let out liquid rock. But they were the means of opening a way for whatever vapors or solutions the melted rock through its heat, supplemented by the earth's crustal heat, might gather from the rocks, or their crevices, along the way up, or from the depths below. The copper veins of the Lake Superior region are an example ; and so are also the richest and the chief part of all the silver, lead, and copper veins of western America, from Fuegia on the south, along the western slope of the Andes to Central America, Mexico, Nevada, Arizona, Colorado, Utah, and Wyoming. The results differ not only according to the kinds of rocks below, but also the kinds along the upper part of the fissure : whether they are (1) of dif- ficult corrosion, or (2) of easy corrosion like limestones. HEAT VEINS. 339 1. The upper intersected rocks of difficult corrosion. These rocks are of any kinds not calcareous : as shales, sandstones, or other related fragmental kinds, or, but much less frequently, crystalline rocks. The famous copper mines south of Lake Superior are an example. The upper intersected rocks are sandstones, conglomerates, and tufas. The igne- ous rock is mainly of the basaltic type. The copper is native copper con- taining generally 3 per cent of silver, and occasionally speckled with silver. It occupies irregular fissures and cavities in the igneous rock, especially its amygdaloidal varieties, and also occurs in the adjoining sandstone. It some- times constitutes amygdules, has often a gangue of zeolites, or coats crystals of analcite and quartz-crystals, and thus it proves its contempora- neous origin with these materials. One great sheet of copper was 40 feet long, 6 feet wide, and 6 inches thick, and weighed, by estimate, 200 tons. The conditions show that the copper came up along with abundant moisture from some deep-seated source. In 1891, the mining at the Calumet and Hecla mine had gone down 4000 feet. It is probable that the deep-seated source was a region of veins in Archaean rocks along the line of the fissure or fissures holding chalcopyrite, the most common of copper ores. Another example is that of the remarkable Comstock lode, Nevada, along a faulted fissure now a deserted mining region. The igneous rock at the broad vein is of the basaltic type, and intersects a region of andesyte of Tertiary age. The ore deposit extends along the contact of the igneous rock with those it intersects. The gangue is mainly quartz. The ore is largely silver sulphides with some native silver and native gold, the last nearly half the value of the products. Hot vapors ascend the opening, and during the working it made the cooling of the air with ice necessary in order to reach the lower depths ; and finally the heat caused the desertion of the mine. By means of the vapors, the diabase and other adjoining rocks had become deeply decomposed to clay. The total yield up to July, 1880, was over 306 millions of dollars. (King, 1870; Becker, 1882 ; Hague and Iddings, 1885.) In other related veins, the rocks cut through by the upper part of the fissure vary in porosity and in other ways ; and some of the beds become impregnated with ores, while others receive little or none. Such impregna- tions are occasionally found where no igneous rock by which they could have been produced is in sight. The following sections, illustrating a case 314. 315. of this kind, are from a report made in 1879, by Kothwell and Crouch, on a district on Virgin River, in Utah, 250 miles south of Salt Lake. The formation containing the ore-beds (o) is probably Cretaceous (see Gilbert's 340 DYNAMICAL GEOLOGY. Hep., 158, 171, 1875). The ore is chiefly silver chloride or horn-silver. The rocks are sandstone, argillaceous sandstone, and shale. The ore-beds are usually clayey layers or shales, and the ore is most abundant when the clays contain vegetable remains. Eruptive rocks are not far away, and J. E. Clayton, in the same report, urges that hot vapors, derived either from the fissures of eruption, or from other wide-spread fracturings made by the erup- tive movements, were the chief source of the distributed ores. In southern Utah and in Colorado, according to J. S. Newberry, veins exist made of coarse gravel and stones, in which the stones have become coated with argentiferous galena and other ores, including silver chloride, that were received from below. They are worked for the silver. Examples are the Bassick and Bull Domingo mines near Silver Cliff, Col., and the Carbonate mine at Frisco, Utah. The large fissures were opened near the base of the mountains, where they became filled with the pebbles, stones, and bowlders of all kinds there accumulated, and yet received the ascending metallic solutions, and also siliceous solutions, which deposited at the Bassick mine much chalcedony among the stones. 2. The intersected rocks of easy corrosion. Many of the richest ore- deposits of the world occupy cavities in limestone made by the corroding action of solutions or vapors. The cavities were eroded usually along joints or fractures of the limestone. Examples occur in the Leadville region, Col- orado ; in the Wasatch and Oquirrh mountains, Utah ; at the Eureka mine, Nevada ; in Lake Valley, New Mexico ; in the Los Carlos Mountains, Mexico ; and elsewhere. The ores of these mines, as generally of others, are of two classes : (1) the original, and (2) the secondary mainly the latter. The original ores include galena (PbS), containing some silver and chalcopyrite, with sometimes pyrite and sphalerite (ZnS). Some of the secondary are silver chloride and bromo-chloride, made from the silver of the galena; lead sulphate, carbonate, phosphate (and less commonly vanadate and mo- lybdate), made from the galena; zinc silicate, made from sphalerite; and also iron oxide (hematite or limonite), made from pyrite and from iron in the limestone ; and manganese oxides, probably from the limestones. The following figures show the forms, at Leadville, of some of the cavities of ore in the corroded limestone (a blue Carboniferous limestone) underneath a sheet of porphyry, the latter being the igneous rock which carried up with it the ore and heated vapors. They are from the very valuable Report of S. F. Emmons (1886). The porphyry is also usually altered and often pene- trated for some distance with ore, and its decomposition has afforded part of the ore for the limestone cavities. Although the ore deposits are usually in a Carboniferous limestone at Leadville, the time of the outflow of the por- phyry and of the making of the cavities was not earlier than the Cretaceous period (Emmons). The similar silver-lead mines of all western America are probably likewise Cretaceous (chiefly the Laramie or later Cretaceous), or else Tertiary. At the famous Eureka Mine, eastern Nevada, where the rocks are all Paleozoic, the eruptions were Tertiary, according to Hague (1892), and mostly late Tertiary ; they were partly along old fault-planes of post-Carbonif- HEAT VEINS. 341 erous age, and partly through new fissures. The ores occur along the dikes, and also penetrate the limestones ; the ejection of the igneous rocks, andesyte and rhyolyte, was accompanied by the upward passage of the ores ; and the ores became much changed to secondary kinds by the action of the vapors. The latest eruptions of the region were of basalt. 316. 317. White Porphyry Gray Porphyry Blue Limestone Vein- Ore material Fig. 316, two Carbonate Hill sections, Leadville, showing cavities of ore in the inclined stratum of limestone, a, limestone; 6, porphyry; c, ore. Fig. 317, section at Printer Boy Hill mine; letters same signification. Emmons. The abundance of chloride and bromide of silver in these western mines makes it probable that sea water contributed to the ascending vapors, and that salt (NaCl) supplied the chlorine. .In the Cretaceous period, the mountain region was mostly submerged. The ores are supposed to have come from the igneous rocks. (Becker, Emmons.) This was probably true to a large extent in some cases, according to the facts afforded by the Kewee- naw copper region. The hot lavas carried much of the metallic material to the surface, and as cooling commenced, the ores were condensed in, or gath- 342 DYNAMICAL GEOLOGY. ered into fissures, and amygdaloidal and other cavities disseminated through the amygdaloidal rock ; and under such conditions they have been mined in. the Keweenaw copper region to the great depth mentioned. At Leadville, and other like regions, the liquid lavas were in part the carriers of the ores and vapors to the surface ; but the chief part of the concentration of the ores and the corrosion of the limestone may have taken place during the cooling of the lavas. The solid rocks of the globe take in their small percentage of moisture from the waters that become subterranean, and then hold it ; a flow of such waters downward through such rocks, and a draining out of their ores, cannot take place, except as complete decomposi- tion is produced ; and the small depth to which decomposition extends in most igneous rocks shows that the process is extremely slow. The processes of decomposition and concentration were long kept in progress by the vapors that continued to rise from below after the eruption had ceased. Finally, the infiltration into the vein, or vein-masses, of cold waters from above has carried on further the work of alteration and corrosion, and this work is still in progress. 3. Ore deposits of doubtful origin occurring in limestone. Great lead deposits occur in Paleozoic limestones of the Mississippi Valley in Wis- consin, northern Illinois, and Iowa, and in Missouri and bordering parts of Kansas and Arkansas. They occupy cavities or caverns in various lime- stones from the Cambrian to the Subcarboniferous. The mines of Wisconsin and Illinois are in the Galena limestone (or the upper part of the Trenton limestone) of the Lower Silurian; those of southeastern Missouri, in the Third Magnesiaii limestone, of Cambrian age ; those of southwestern Mis- souri, in the Keokuk limestone of the Subcarboniferous period, and to a small extent in the Cambrian ; those of central Missouri, chiefly in the Cambrian limestone, but partly in the Subcarboniferous limestone. The lead ore, galena, is associated with pyrite, marcasite ; the zinc ores, calamine (zinc silicate) and smithsonite (zinc carbonate); lead carbonate, malachite, barite, and in some places with black cobalt and an ore of nickel. The ore, in each of the regions mentioned, occurs in cavities or caverns in the different limestones. From the resemblance between the various deposits, it is concluded that the time of origin was the same for all, and not earlier than the Subcarboniferous period, the age of the latest of the limestones. As first made known in the geological report of Wisconsin by J. G. Percival (1858), the ore-bearing cavities follow the courses of the joints (or system of fractures) in the limestone, and are most extensive along the larger joints, which are sometimes the lines also of faults. This fact has been confirmed by later observations. In the Transactions of the St. Louis Academy of Science for 1875, A. Schmidt announced the conclusion that the ore-containing cavities in the Missouri limestones were made when the alterations of the galena took place, producing the associated minerals, and principally in the more porous HEAT VEINS. 343 part of the limestone stratum where limited above and below by cherty layers ; that the rock adjoining was largely converted into dolomite by mag- nesian solutions, and that this " dolomization " was an early step in the process, and aided in making the cavities ; that the ores often occur mixed up with chert or sand that were set loose by the decomposition of the lime- stone. There are two theories of origin, one deriving the ore from above, the other from below. The former is favored and the latter opposed by the absence of proof that the bodies of ore extend downward through the lime- stone vein-like, and that igneous action was concerned. The theory of filling from above encounters the objections that the ores of lead are not soluble, and could not have been carried into the cavities in solution by sea water, and that the gathering of galena from Archaean veins, once in .the regions, by abrading and transporting waters, is improbable, and does not account for the presence of the eroding agents which made the cavities. The other theory, which was suggested by Percival, and is advocated by Jenney (1893), makes the deposits similar in origin to the silver-lead deposits of Leadville and other Kocky Mountain localities. But the objections to it mentioned above exist; and so they do in the case of some Colorado ore deposits, where igneous action below is nevertheless believed to be probable. The making of the ore deposits is generally referred to the close of Paleozoic time, when the Appalachians were made ; but Jenney supposes it to have been at the close of the Cretaceous period, simultaneous with that of most Colorado deposits. In Derbyshire, England, the Subcarboniferous limestones contain similar lead deposits, and along with the ores are Permian fossils, proving that they originated not earlier than the Permian. The different modes of origin of ore-bearing deposits, above described, are the following. In the deeper veins the earth's interior heat has been accessory to special sources of heat. A. HEAT FROM CRUSTAL MOVEMENTS, AND NOT FROM IGNEOUS EJECTIONS OR HOT SPRINGS. (1) Regular veins. Mostly in metamorphic rocks. (2) Grouped interlaminar veins. Generally short, as the smaller auriferous quartz veins of gold regions, and some tin, copper and other veins. B. HEAT FROM IGNEOUS EJECTIONS, VAPORS, AND HOT SPRINGS. (3) Ore impregnating non-calcareous rocks. (4) Veins or groups of veins intersecting non -calcareous rocks. (5) The ores in veins intersecting calcareous rocks, and occupying cavities in them made by their corrosion. Often combined in the same region with 3. Besides these there are, of uncertain origin : (6) Cavities supposed to be in part previously made limestone caverns, as those of the Mississippi Valley. 344 DYNAMICAL GEOLOGY. The principal kinds of ore deposits that have no relation to veins are as follows : (1) Beds of iron ore called lirnonite, including marsh-made ores (page 128), sometimes containing also manganese oxide, cobalt oxide, and some black copper oxide ; (2) beds consisting of concretionary masses of clay iron-stone, the ore either hematite, limonite, or siderite, common in coal regions ; (3) beds of hematite and magnetite in inetamorphic and other rocks, which often stand vertical and look like veins, whence they are sometimes so called ; (4) auriferous gravel deposits along valleys, made by the degradation of schists that are intersected by veins of auriferous quartz. * 4. Sediment-filled fissures. Fissures have sometimes become filled with sand or gravel from the adjoining beds. Near Astoria, Oregon, occur several large sandstone veins of this kind. One of them, half a mile above that place (Fig. 318), is five feet wide, and extends the whole height of the bluff; it has two transverse faults, the upper one eight feet. The filling is granitic sandstone, like that of the inclosing rock. Another, 18 inches wide, is shown in Fig. 319; it is in the same rock two and one half miles above 320. 318. 319. Figs. 318, 319, sandstone veins, near Astoria, Oregon. D., 1849. Fig. 320, sandstone veins, south of Shasta Peak. Diller, 1890. Astoria. Fig. 320 represents similar sandstone veins from the coast region in California, south of Mount Shasta, described by J. S. Diller (1890). Diller infers, from his observation, that the fissures were filled from below by upthrust force during the progress of an earthquake. HYPOGEIC WORK. 345 VI. EARTH-SHAPING, MOUNTAIN-MAKING, AND THE ATTENDANT PHENOMENA: HYPOGEIC WORK. The preceding chapters on the origin of geological phenomena treat of the agencies by which rocks were made, denuded, crystallized, and filled with veins and ores. The subject of the present chapter is the nature and origin of the changes through which the earth has received its form and features, hypogeic work, of which the erogenic part is the most noticeable. It does not comprise the work of waters in giving mountain-like shapes to plateaus, and thus producing mountains of circumdenudation, or in making, by accumulation, hills of detritus ; nor the work of heat in building up vol- canic cones, the earth's mountains of igneous accumulation, or in making laccolithic domes or masses (laccoliths) mountains of subterranean igneous accumulation; for these operations have already been considered; but work that is consequent, whatever its source, on crustal and interior movements in the earth, as expressed in the term HYPOGEIC, from the Greek VTTO, beneath, and yfj, the earth. The attendant phenomena comprise fractures of the earth's crust and supercrust, dislocations, flexures, crystallization and alteration of rocks, rock-melting, and other effects. The facts and explanations here presented are supplemented in the fol- lowing pages on Historical Geology, and the chapter will be best under- stood if those pages have already been made familiar. ACTUALITY OF CHANGES OF LEVEL. All geological history testifies against the stability of the rocky crust of the globe ; and if the earth, as is believed, has cooled from fusion, abundant reason for this unstableness exists ; for the effects of the earth's slowly pro- gressing refrigeration reach backward indefinitely, and downward beneath all other agencies of change. But the evidence of instability, although the fact is so obvious, is beset with doubts as to amount and position, because of possible and actual varia- tions in the base from which measurements are -naturally made. This base is the water-line about the land. Hence, we have to consider the sources of variation in sea level. 1. Changes in the level of the sea-bottom. When water-made strata full of marine fossils are found at a height of 1000 feet above the sea, the evidence of a rise of at least 1000 feet appears to be plain. Yet, a lowering of the sea-bottom might produce the same result ; and it may, therefore, be a question whether in such a case part, or all, of the apparent upward change has not been so produced. So, also, by a reverse movement in the sea-bottom, an apparent subsidence might result. Here there is actual change of level, but it may be thousands of miles away from the land along which the change is made visible. Change so caused will affect all seacoasts alike; and in this fact a criterion exists for judging of its reality. 346 DYNAMICAL GEOLOGY. 2. Changes in the position of the earth's axis. If a change should take place in the position of the earth's axis, through changes of level in the earth's crust, the coast-lines of the earth would be throughout affected by the new adjustment of the water level. Physicists have very nearly relieved geology of this source of doubt, by the decision that an effective change of this kind is exceedingly improbable (page 255). 3. A change in the level of the land. By the law of gravitation, elevated lands attract, and thus draw the mobile waters of the ocean toward them to a height dependent on their mass and distance. Consequently the sea- margin of all coasts is more or less displaced, and much so, wherever the land mass adjoining rises high above it. It has been calculated that from this cause the sea level at the center of the Eurasian continental mass is about 2900 feet above the sea at its margin (R. S. Woodward) ; at the center of the Australian mass, about 400 feet (G. G. Stokes, 1849, 1887) ; of the great plateau of India, 1000 feet, but under the volcanic mountain of Maui, Haleakala, 10 in mean slope, only 10 feet. The facts make it evident that the water-line along nearly all coasts, and especially on the west coast of North and South America, must be very largely moved inland by the mountain chains ; and that, through geological time, changing levels have always been changing the water-lines. It is to be observed, furthermore, that this inland drawing of the ocean's water dimin- ishes the height of the mountains above the sea. The error is on the side of too little height. The piling of ice over the land in a glacier epoch has a like effect, but with material having about two fifths the gravity of the ordinary land material. Were the ice of a glacial epoch to be accumulated about the poles, and thus make a polar ice-cap or meniscus thousands of feet high, the ocean level would be changed through all latitudes to the equator. This cause has been thought sufficient to explain apparent subsidences in the hemisphere so capped. But since the change of water level from the equator to the pole would follow a geometric ratio, admitting of mathematical calculation, the accord- ance of the theory with actual facts is easily tested. In eastern America the subsidences closing the Glacial period supposed to be thus accounted for by Croll have no correspondence with the required heights. Moreover, observations have proved that there was no such polar ice-cap in the Glacial period. 4. Abstraction of water from the ocean. Further, the making of great continental accumulations of ice would lower the level of the ocean and tend to raise the apparent level of the land. With the above cautionary considerations in view, noting that the obser- vations about ice relate only to glaciated regions, that the error from the attraction of the land is on the side of too little height, and that sea-bottom changes of level affect all coast-lines alike, the following facts may be ac- cepted as proof of changing levels over the earth's surface. HYPOGEIC WORK. 347 EXAMPLES OF CHANGES OP LEVEL IN THE LAND. 1. Movements, up or down, are now going on along the coast of North America, Scandinavia, Greenland, and elsewhere. Alexander Agassiz states that at Tilibiche, in Peru, there is a coral limestone, 2000 to 3000 feet above the sea level, extending along for 20 miles, in which occur corals modern in aspect ; and that the existence, in Lake Titicaca, of eight species of a salt- water genus of Crustaceans, Allorchestes, suggests the presence of the sea over this region, 12,500 feet in height, at no very distant period. There is no proof of corresponding changes over eastern South America. 2. On the coast of Cuba, limestone strata, made in the sea off the shores, are now (according to W. 0. Crosby) at different levels up to a height of 1800 feet, and near Havana, over 1200 feet ; and on Jamaica (ac- cording to Mr. Sawkins), and Haiti (according to W. P. Blake), of 2000 feet. 3. In the early Tertiary, the European and Asiatic seas contained Num- mulites, and limestones were made of the multiplying disks. Now, those Eocene Nummulitic beds are at a height of 9000 feet in the Pyrenees, 11,300 feet in the Alps, 16,500 feet in the Himalayas in western Tibet, and a few hundreds only near Paris. 4. In the Cretaceous period, the region of a large part of the Rocky Mountains and of the Atlantic, Gulf, and Pacific borders of the continent were beneath the sea, but mostly near its surface ; and the marine life of the sea contributed to the forming of Cretaceous beds. Now, the marine beds, filled with Cretaceous fossils, are at a height of 10,000 to 11,000 feet in the Rocky Mountain region ; at a maximum height, on the Pacific border, of only 5000 feet ; in Alabama of 700 to 800 feet ; and in New Jersey not over 400 ; and in portions of the western mountain regions the beds are in great flexures. 5. In the Appalachian region, from the site of Albany, N.Y., to Ala- bama, at or near the end of the Carboniferous period, the surface was near the sea level, and the rocks, from the Cambrian to the Carboniferous, lay in a horizontal pile, the upper surface little emerged above sea level. Now, they are in mountain flexures, and heights of several thousand feet occur along the line. 6. All the world's mountains, excepting those of igneous formation, consist of rocks that were made chiefly in the sea ; and the highest of them reached their present level during the latest of the geological ages. And while some portions of the earth's surface were raised in later geological time 10,000 to 19,000 feet, other parts underwent little or no recognizable elevation. 7. Formations of all thicknesses to tens of thousands of feet bear evi- dence of the shallow-water origin of the successive beds ; and they thus prove that, while forming, a subsidence of extreme slowness was in progress over the great area; slow enough for the accumulation of the material in the surface waters by living growth if the beds consist of limestone, and by 348 DYNAMICAL GEOLOGY. water-action, if of sedimentary origin. The shallow-water origin of beds is so generally true that thick formations in almost all cases are proof that a slow subsidence, equal in amount to the thickness, was going on over the area during the deposition ; and also that without such a subsidence the making of thick strata or formations has rarely taken place. Such evidences of actual change of level are good, and have profound significance. Geology has thus proved that : 1. Unequal changes have been in progress simultaneously in different parts of the same continent. 2. The changes in level have usually gone forward with extreme slow- ness by the few inches or feet a century, though sometimes also by abrupt displacements. The former are termed secular changes, the latter paroxysmal. Another class of facts is represented by the following from Illinois : A section of the coal formation of Illinois, described by Worthen, con- tains 16 coal-beds, large and small, separated by fragmental beds and lime- stones containing abundant remains of marine life. The coal-beds indicate eras of emerged land, the marine fossils, intervening eras of submergence, and their number shows that at least sixteen alternations between the two con- ditions there took place in the Carboniferous period. Facts make it certain that the great Interior Sea of the continent communicated at that time freely with the ocean to the south. The same region thus went up and down, changing the dry land outline and the sea depths ; and the changes went on with extreme slowness, for coal-beds, as well as the much thicker marine beds, were slow in accumulation. Facts of similar import are afforded by all the successive formations, from the Cambrian upward, and alike on all the continents. In explanation of such changes it may be questioned whether subsidences over the sea-bottom may not have produced some or all of these oscillations in level. As far as evidence can be obtained, the changes were independent of movements in the ocean ; for the coal-beds of Illinois and those of Ohio and Pennsylvania do not show that uniformity of parallelism which this hypothesis requires. Further : changes of level are now in progress, both of the slow secular kind and of the sudden or paroxysmal. The following sketch represents a case in which a Roman temple has passed through a time of partial submergence below the level of the Mediterranean. The temple is that of Jupiter Serapis at Pozzuoli. It was originally 134 feet long by 115 wide ; and the roof was supported by 46 columns, each 42 feet high, and five feet in diameter. Three of the columns are now standing, and they bear evidence of submergence for a considerable time to half their height. The lower twelve feet are smooth ; for nine feet above this, they are penetrated by lithodomous or stone-boring shells, remains of which (a species now living in the Mediterranean) were found in the holes. The columns, when submerged, were consequently buried in the mud of the bottom for 12 feet, and were then surrounded by water nine feet deep. The pavement of the temple is now under water. Five feet below HYPOGEIC WORK. 349 321. it, there is a second pavement, proving that these oscillations had gone on before the temple was deserted by the Romans. It has been stated that, for some time previous to 1845, a slow sinking had been going on, and that since then there has been as gradual a rising. At the earthquake in 1819, about the delta of the Indus, an area of 2000 square miles became an inland sea ; and the fort and village of Sindree sunk till the tops of the houses were just above the water. Five and a half miles from Sindree, parallel with this sunken area, a region 50 miles long and in some parts 10 broad was elevated 10 feet above the delta. The natives call it, with reference to its origin, Ullah Bund, or Mound of God. In 1838, the fort of Sindree was still half buried in the sea; and, during an earth- quake in 1845, the Sin- dree Lake was turned into a salt marsh. In 1822, the coast along by Concepcion and Valparaiso, for 1200 miles, was shaken by an earthquake; and it has been estimated that the coast at Valparaiso was raised three or four feet. In February, 1835, an- other earthquake was felt from Copiapo in Chile, eastward beyond the Andes to Mendoza. Captain Fitzroy states that there was an elevation of four or five feet at Talcahuano, which was reduced by April to two or three feet. The south side of the island of Santa Maria, near by, was raised eight feet, and the north, ten feet ; and beds of dead mussels were found on the rocks, ten feet above high-water mark. The secular movements which have been observed are confined to the middle and higher temperate latitudes, and may be a continuation of the series which characterized the earlier part of the Quaternary age. In Greenland a slow subsidence is taking place. For 600 miles from Temple of Jupiter Serapis. 350 DYNAMICAL GEOLOGY. Disco Bay, near 69 1ST., to the Firth of Igaliko, 60 43', the coast has been sinking for four centuries past. Old buildings and islands have been sub- merged; and the inhabitants have had to put down new poles for their boats, the old ones standing, Lyell observes, "as silent witnesses of the change." On the North American coast, south of Greenland, from Labrador to New Jersey, it is supposed that similar changes are going on. G. H. Cook concludes, from his observations, that a slow subsidence is in progress- along the coasts of New Jersey, Long Island, and Martha's Vineyard, and has deduced, from the positions of buried stumps over large areas along the New Jersey coast, a rate of two feet a century. According to A. Gesner the land is rising at St. John, in New Brunswick ; sinking at the island of Grand Manan ; rising on the coast opposite, at Bathurst ; sinking about the head of the Bay of Fundy, where there are regions of stumps submerged 35 feet at high tide, and about Minas Basin, in Nova Scotia, except, perhaps, on the south side. On page 149 the reasons are given for believing that coral reefs and islands are proof of a slowly progressing subsidence, as first suggested by Darwin. On the physiographic chart, page 47, the line CCC, extending in an easterly direction from the Pelews, divides coral islands from those not coral. Over the area north of it, to the Hawaiian Islands, all the islands are atolls, excepting the Marquesas and three or four of the Carolines. If, then, the atolls are registers of subsidence, a vast area has partaken in it, meas- uring 6000 miles in length (a fourth of the earth's circumference), and 1000 to 2000 in breadth. Just south of the line there are extensive coral reefs; north of it the atolls are large, but they diminish toward the equator, and mostly disappear north of it; and, as the smaller atolls indicate the greater amount of subsidence, and the absence of islands still more, the line AA may be regarded as the axial line of this great Pacific subsidence. The amount of this subsidence may be inferred, from the soundings near some of the islands, to be at least 3000 feet. But as 200 islands have disappeared, and it is probable that some among them were at least as high as the average of existing high islands, the subsidence in some parts cannot be less than 5000 feet. This sinking probably began in the Tertiary era. During the progress of this subsidence, or since it ceased, there have been many cases of isolated elevation. The following are some examples from the Pacific: Oahu (Hawaiian Islands), 25 feet; Elizabeth Island, Paurnotu Archipelago, 80 feet ; Metia or Aurora, 250 feet ; Atiu, Hervey Group, 12 feet ; Mangaia, 300 feet ; Rurutu, 150 feet ; Eua, Tonga Group, nearly 500 feet; Vavau, 500 feet; Savage Island, 100 feet; Eota and Guam, of the Ladrones, 600 feet. More than 25 others have undergone some elevation. Off the New Guinea coast, some atolls have been raised to a height of 300 or 400 feet, and a central basin 100 feet deep, with vertical walls around, occupies the place of the old lagoon. HYPOGEIC WORK. 351 Thus the earth is still undergoing changes from paroxysmal movements and prolonged oscillations. The changes, while probably more restricted than in the ages of progress, are yet the same in kind. CHARACTERISTICS OF DISTURBED REGIONS AND MOUNTAINS. General Explanations. 1. The general range of effects. A disturbance, in geological usage, is an event in which rocks formations of wide extent are moved, and more or less fractured in the process. Over some great areas they have been shoved up or depressed with little variation from horizontality ; and over others there have been profound flexures and faults involving thousands of feet of strata throughout regions hundreds of miles wide and thousands long. Explanations and illustrations have already been given of upturned beds, flexures, faults, and flexure-faults (page 99), and of the metamorphism and vein-making, which have attended great mountain-making movements. The object of the present chapter isvto present all the various orographic phenomena in their relations as they occur combined in the structure of mountain ranges and systems of ranges, and to explain, so far as is at present possible, the origin of orographic movements and of the resulting structures. In the first place, some facts in- molecular physics of fundamental impor- tance as regards flexures, fractures, and faultings of solids, are here briefly illustrated, and then follow descriptive examples of several mountain-struct- ures, as a prelude to the discussion of the question of origin. 2. The flow of solids. Solid metal and rock, when under pressure, as first illustrated by Tresca, yield through molecular movement, and may thus become compressed, drawn out, flexed, and otherwise deformed. The yield- ing is very much like that in a bent bag of shot, through movements in the shot. In the case of metals, ice, and rocks of even texture, the change, if slow enough, may take place without fractures. In the bending of a mass of rock or ice by gravity, molecules of one side push the adjoining, and these others throughout the mass, until the adjustment is complete. Hence the density is nowhere changed. The flow of metals is now util- ized extensively in the shaping and punching of cold metal for various purposes in the arts. In experiments at the Stevens Institute, Hoboken, by Mr. David Townsend (Journal of the Franklin Institute for March, 1878), rectangular blocks of iron, accurately planed and measured (being made about 1-75 inches wide and thick, and 2-5 inches long), were punched cold through the center with a punch T 7 g of an inch in diameter. The core which came out (Fig. 323) was only J-i of an inch (instead of 1-75 inches = -f f ) long ; and yet, like the punched block, it was essentially un- changed in density. Mr. Townsend's experiments and measurements show that six tenths of the metal which had filled the hole had moved off lat- 352 DYNAMICAL GEOLOGY. erally, or in the direction of the width and length of the block ; and this lateral movement or flow had bulged the sides much more at bottom than at top, and most about the middle. At 322 v bottom the block was increased -^ in width and --$ in length. The block had been made of plates of iron welded to- gether, and these were bent downward as the punch passed in, the lower ones the least; and Fig. 322 shows the ap- pearance of the surface, after polishing and etching with acids, of a section through the middle, when the punch had entered 1J inches, and the core pro- jected an eighth of an inch. Such facts, together with those re- lating to the heat developed by friction, take the mystery out of the process of flexing rocks. 3 Fractures and displacements under pressure. The production of fractures through lateral pressure has been experi- mentally illustrated by Daubree. In one of his experiments he used an oblong square prism consisting of layers of Core out. Townsend. beeswax, and applied the force at the middle of the two ends after protecting them by small blocks or plates of the same cross-section. Fig. 324 repre- sents, half the natural size, the prism ready for the experiment. One of the results, after applying the pressure, is shown in Fig. 325 ; and another, after using a stronger pressure, in Fig. 326. In both, a flexure becomes the course of a fracture, and also of a fault ; and in 326 it is shown that the flexure-fault is not at the axis of the flexure, but beyond it, between the anticline and syncline. In Fig. 327 are shown 324. Punch at a depth of 1 inches. 323. Prism made of layers of wax of different colors, (x 3.) Daubree. two oblique fractures and faults, obtained in another trial. The fractures have their planes parallel as well as very oblique ; and the faults were made by a shove up along the oblique surface. So the greater fractures of mountain regions usually have like obliquity as well as parallelism, and HYPOGEIC WORK. 353 sometimes large displacements in the same upthrust way. The direction of dip of the plane of fracture, as the figures show, is, in the case of a synclinal 325. 326. bend, the reverse of that in the anticlinal. In subjecting to vertical pressure a square block of wax, having a breadth of five and a half inches and a height of about a foot, an oblique diagonal fracture was made with some bulging of the sides ; and, adjoining the fracture, as a consequence of the molecular movements in the bulging, fine rectangular cracks were produced, like a delicate net- work. Cubes of hard rock under vertical press- ure usually break off at the angles and edges, leaving two rounded cones with their apexes at the middle ; but a tabular block of limestone was reduced by Daubre"e to vertical prisms and plates. ' CHARACTERISTICS OF SOME TYPICAL MOUNTAIN RANGES. 1. The Appalachian Mountain Range. The structure of the Appalachian Mountains was first investigated by Professors W. B. and H. D. Kogers in connection with geological surveys of the States of Virginia and Pennsylvania; and their results (1842) gave many fundamental principles to orographic science. Fig. 328, A, B, sections of part of the belt in Virginia, by H. D. Campbell, afford a general idea of the system of flexures (1893). Each represents the rocks for a breadth of about 10 miles across the range, in Eockbridge and Bath counties. Between the two sections there is an interval of about eight miles. The numbering of the formations corresponds with that on page 410 ; the limestone areas are blocked, the shales ruled, and the sandstones dotted. Farther to the southeast, in the same line, there are closely crowded over- thrust flexures. In the construction of the mountain range from New York to Alabama (1) the whole Paleozoic series of strata to the floor of crystalline Archaean rocks in some parts 40,000 feet thick were involved in the system of flexures ; (2) the flexures are generally parallel to the axis of the mountain DANA'S MANUAL 23 354 DYNAMICAL GEOLOGY. range ; (3) the axis is usually nearly straight, but sometimes bends around through a large arc; (4) instead of one flexure for the range, or parallel flexures of like length, there is generally a succession along the mountain region, one rising near where another ends, making overlapping series. There is no crumpling of the beds, and no long intervals of horizontal beds alternating with the flexed. Some single flexures are 80 to 100 miles long ; and they vary in span from one mile or so to 20 or more. In the finer kinds of rocks flexures occur of a few inches or less, which are like wrinkles on the great rock-sheets. (5) The flexures have rarely the ridge line horizontal; and, in adjoin- ing flexures it often inclines in opposite directions, this being a mechanical effect in the process of warping. Further (6), the axial plane of a flexure is seldom vertical, the opposite slopes, in a transverse section, being unlike ; hence the flexures are mostly unsymmetrical, even when not overthrust flexures (page 103). Again (7), the flexures have the steeper side generally facing northwest, away from the Atlan- tic Ocean; at the same time they are by far the most numerous and close- pressed, and most generally overthrust, in the eastern part of the range, or the side toward the ocean. The mountains have consequently a front-and-rear structure, the front side facing the ocean. This flexing of rocks to such depths appears less incredible when it is noted (a) that the strata so treated were generally those of sedimentary formations ; (6) that they were, for the most part, only partially consoli- dated, the limestones excepted; (c) that all the rocks contained much moisture, and had their cohesion diminished thereby ; (d} that as the move- ment proceeded, heat was being generated by friction, which, if low in degree, made siliceous solutions that would diminish friction by the dissolv- ing action, and, if high, produced superheated vapor and a general softening of the flexing masses. Again (8), great upthrust faults, with displacements 10,000 to 20,000 feet or more, exist in the region of flexed rocks, and especially where the flexures are overthrust and close pressed ; and they are sometimes, if not generally, flexure-faults, with the thrust westward along the flank plane of the overthrust flexure. Professors W. B. and H. D. Rogers, in their ad- mirable paper on the Appalachians, observe that " the passage of an inverted fold into a fault is of common occurrence," and that some flexure-faults have, "in southwestern Virginia, a length of about 100 miles." They always occur on the northwest side of the flexure, as in the following figures taken from two of their sections ; and they begin, say these authors, with the thinning, or "disappearance of one or more of the groups of softened strata lying immediately to the northwest of the more massive beds." " The dislocation increases as it is followed along, until finally the lower beds (II) of the Lower Silurian are found resting directly on rocks of the Carboniferous series (X, XI)." These two sections are from the same fault, the first near its place of beginning, and the second, where the HYPOGEIC WOBK. 328. 355 IBack Creek //' Mill Mountain Back Creek Mountain -CoM.Sulphur Springs Waif Pasture River &? The Knob Jackson River ^-Little Calf Pasture River *Warm Springs W.arm Springs Mtn. Little North Mtn. Jump Mountain ill Littl.e Piney Mtn. Little Mare Mta. 356 DYNAMICAL GEOLOGY. condition is nearly that just stated, the lower beds (II) being in contact with the Devonian (VIII). In the former, III and V (Hudson Eiver and Clinton shales), of the flank of the anticline, are greatly thinned down (as compared with the thickness on the other side of the flexure). To the southwest the strata successively disappear until the condition in Fig. 330 329. III IV V VII V IV III 11 exists ; and then that in which II and XI, both great limestones, are in con- tact. But, as they state, the ingulfed strata may, in some places along the course, be found standing in isolated knobs between the two formations, II and XI. The Professors Rogers observed, as reported by Lesley, that the lines of faults of Virginia are continuous with flexures in Pennsylvania. Just beyond the cluster of great faults in the Appalachians comes the high plateau, or table-land, characteristic of the northwest border of the Appalachian Range. In East Tennessee it is called the Cumberland Table- land; Fig. 331, by Safford, represents it with the height proportionally 331. N. w. .S. E. Cumberland Table-land, Tennessee; c, Crab Orchard Mountain; 2, Cambrian; 3, 4, Lower Silurian (Calciferous and Trenton); 5, Upper Silurian; 7, Devonian (Black shale); 8, Subcarboniferous; 9, Coal measures. Vertical scale 2000 feet = 1 inch ; horizontal, 12 milea = 1 inch. much exaggerated. It is 2000 feet high, and 900 to 1200 above the Great Valley of East Tennessee (the low eastern part in the figure), which is the region of the great flexures and faults reduced to a valley by denudation. HYPOGEIC WORK. 357 The width is 40 miles for the higher part, and 25 to 30 for the lower western portion. Farther west is the central basin of Tennessee, a region of Lower Silurian rocks. Tennessee thus owes its grander features, its high eastern table-land, and its transverse plain beyond at a lower level, to move- ments attending the making of the Appalachian Mountains, and the denuda- tion which ensued. The Cumberland Table-land is continued northeastward through Virginia and Pennsylvania to southern New York and the Catskills ; and in this northern part it is over 4000 feet high, and fronts the Hudson River Valley with precipices of nearly 2000 feet. The Great Valley of East Tennessee becomes, as the Professors Eogers observed, the Shenandoah Valley in Vir- ginia, the Cumberland Valley in Pennsylvania, the Kittatinny of New Jersey, and the Newburg part of the Hudson River Valley in New York. This prolongation of prominent features, orographic and denudational, gives an individual character to the Appalachian Range. Lesley's colored geological map of Pennsylvania, the first in his geological atlas of counties, illustrates well the interlocking flexures in the rocks as they pass through the state, with the great table-land region on the west and north. The facts are displayed also on his topographical map of the state, a reduced copy of which is introduced on page 730. (9) The making of the Appalachian Mountains went forward after the close of the Carbonic era, and hence the mountains stand as a fitting time- boundary to Paleozoic history. (10) During all Paleozoic time, the pre- paratory work of making the rocks was slow in progress. Moreover, the deposition of the 30,000 to 40,000 feet of strata took place within a gradu- ally deepening trough, or geosyncline, the deepening so gradual that the deposition kept pace with it. The great trough had an area as long and wide as that of the future mountain range. The Paleozoic strata in it have consequently a thickness 20,000 to 25,000 feet greater than the same series of strata in Indiana and Illinois regions outside of the geosyncline. This depth is made certain by the fact that the Carboniferous marshes nowhere lay much above the sea level when the Paleozoic series was completing. (11) Facts indicate that the trough had some subordinate longitudinal flexures along its bottom; but still, as the diminution westward in the thick- ness of the beds shows, it was one trough. The knowledge of the Appalachian facts led Professor James Hall to sug- gest in 1859 that a similar trough of deposition preceded the upturning in all cases of mountain-making. It was the first statement of this grand prin- ciple in orography. 2. The Post-Triassic or Palisade System of Ranges in Eastern North America. The Palisade mountain system comprises eight to ten independent ranges. They occur at intervals over a region 1000 miles long, extending from Nova Scotia and Prince Edward Island on the north, southwestward to the 358 DYNAMICAL GEOLOGY. northern limit of South Carolina. The ranges are from 10 miles in length to about 350 miles ; and their general course is closely parallel to that of the Appalachian Mountains, even to its westward bend in Pennsylvania. They overlie Archaean or Cambro-Silurian rocks. The Connecticut River Range is 120 miles long ; and the " Palisade Range," extending from southern New York, on the Hudson, into Virginia, is 350 miles long. See, further, the account of the American Triassic under Historical Geology. The rocks are solely Triassic in age. The depth of the rocks of the ranges varies from 3000 to possibly 8000 feet. Facts prove that they were laid down in. each case in an independent, gradually deepening geosyncline. The strata, through the whole 1000 miles, are alike in their essentially fresh-water or brackish-water formation ; in the granitoid origin of the sand- stones and shales, as well as in their general system of structure. The dip of the beds is, with rare exceptions, monoclinal, and mostly between 5 and 25 in angle. In the Connecticut Valley, it is 5 to 25 eastward. In the Palisade belt, about the same westward. In two North Carolina belts, the eastern has eastward dip, and the western, westward. Flexures are local, and of rare occurrence. The only marked one that has been reported is a large syncline in the short Richmond basin. The rocks are much faulted. But this is not evident in large visible displacements along fractures, but in the striated or scratched surfaces over large areas, which indicate the slipping of bed on bed, and along the surfaces of the numerous small fractures ; sometimes all sides of blocks, even when they are no larger than the hand, are striated. All the Triassic areas have their lines of trap-dikes ; and the associa- tion of the igneous rocks with the stratified is so intimate and so extended that the two must have had in some way a common history. The ejection of some of the trap, moreover, preceded the later depositions of sandstone. The trap-ridges, which consist of a large trap-mass, generally 200 to 300 feet thick, underlaid, and partly overlaid, by sandstone, have usually a bold palisade-like front (page 804), of which the "Palisades" on the Hudson are an example, and the name Palisade System is, therefore, an appropriate name for the system of ranges. The facts indicate (1) a general unanimity of movement in a series of geosynclines or troughs that were wholly separated from one another in fcheir rock-making ; and (2) a disturbance that resulted almost everywhere in monoclinal uplifts of low angle, and was accompanied in most parts, now and then, or at the close, with fissure-ejections. There is hence a combina- tion in the Palisade System of eight or ten individual mountain ranges. In the nearly total absence of flexures, the ranges differ from the Appalachian Range, while like it in the preparatory geosyncline of deposition and in the occurrence of great faults. The Sierra Nevada Range is supposed to have been made at the close of the Jurassic, or a period later. HYPOGEIC WORK. 359 3. The Laramide Mountain System, including the Wasatch Range. The Laramide system of mountain ranges extends along the summit of the Rocky Mountains far northward into British America, and southward into Mexico. In British America, just north of Montana, the upturned belt lies east of the Archaean protaxis. In the United States it occupies the summit region of the mountains, between the line of the Wasatch Archaean and the Front Range or protaxis. Dr. G. M. Dawson states that, in British America, the belt of upturned rocks along the summit of the Rocky Mountains extends from Montana northwestward, with a small interruption, to the Arctic Ocean, which it reaches west of the Mackenzie delta. The rocks involved were those of all Paleozoic and Mesozoic time, Cam- brian beds making the bottom, and the Laramie, or the uppermost forma- tion of the Cretaceous, the top. The whole thickness of the series in British America, between 50 and 54 K, is 34,000 feet (R. G. V. McConnell, 1887), and in the region of the Wasatch, about 31,000 feet (C. King, 1878) ; as nearly as has been learned this was the final depth of the geosyncline in which the deposits were accumulated. The facts from British America, as reported by McConnell (1887) and Dawson ( 1886), are much like those of the Appalachian region. The following figures, by McConnell, from a point in the range not far from the line of the Canadian Pacific Railway, show the Cretaceous rocks 332 333 Cr (Cr, Cr) overlaid by the Cambrian (C), or the bottom beds of the Paleozoic, almost horizontally for a width of two miles ; and the describer states that the whole width of the overthrust of the Cambrian at this place is, by his estimate, seven miles. These Cambrian beds are overlaid on the west by Devonian beds (D), and by the Carboniferous (Cb f , Cb'), which have a fault (F) between them. The thrust is away from the ocean, as in the Appa- 360 DYNAMICAL GEOLOGY. lachian region of east Tennessee ; and other flexures in this part of the region are overthrust in the same way. In the western half of the disturbed belt Silurian and Devonian strata occur, and there is one fault in which the thrust is westward. Similar facts and sections are reported by Dawson from the country just south, between the parallels of 51 and 49. 335. Map of the Wasatch Mountains and adjoining part of Utah. Reduced from the large colored plate of the Atlas of the Fortieth Parallel Survey. To the south of this region, in western Wyoming, according to A. C. Peale (1877) and 0. St. John (1878), there are sections similar to those HYPOGEIC WORK. 361 described by McConnell and Dawson. Farther south, in Utah, stands the Wasatch Range of the same Laramide system. The accompanying map of the Wasatch is a reduction of the colored geological map in the Atlas of the Eeport of the Fortieth Parallel Survey under Clarence King, and the highly instructive facts here presented are from King's volume. The Wasatch Mountains extend for more than a hundred miles along the east side of the Great Salt Lake Valley. They face west with a bold front, rising abruptly from the plain to a height of 5000 to 6000 feet, which is 10,000 to 12,000 feet above tide level. At the western foot are Ogden, Uinta, Salt Lake City, and Provo. The eastern slopes are more gradual. East of its southern half stretch away the Uinta Mountains for 150 miles, a great east-west plateau, or table-land, feebly anticlinal in structure, and 10,000 to over 13,000 feet high. Only one fourth of its length is within the limits of the map. North of the Uinta Mountains there is the great "Wasatch Eocene basin," lettered W on the map, 5000 to 7000 feet above the sea level, and south of it the " Uinta Eocene basin," nearly 10,000 feet high, let- tered U. One remarkable feature of the Wasatch Eange is its backbone of Ar- chaean rocks along its western front, a mountain range of Archaean origin which stood there, submerged or emerged, through all the rock-making and mountain-making of Paleozoic and Mesozoic time, the prototype and model- ler of the later Wasatch Mountains. There are four Archaean areas in sight along the range, indicated on the map by the Nos. 1 to 4, and by a covering of small v's. Commencing at the north, Nos. 1 and 2 are short, but No. 3 has a length of 25 miles. Between No. 3 and No. 4, and nearly abreast of the Salt Lake City site, comes the great gap of 15 miles in the Archaean. South of the gap, No. 4 has a height of 11,295 feet, but just to the east of it is Clayton Peak, also Archaean, 11,889 feet. The rocks of the Wasatch Mountains include those of the long series from the Cam- brian to the Upper Cretaceous. The Cambrian areas are lettered C ; they are the black areas finely lined with white. The Carboniferous are lettered Cb (Cb 1 , Cb 2 , Cb 3 ) ; the Cretaceous, Cr (Cr 1 , Cr 2 , Cr 3 , Cr 4 ) ; the Silurian, S ; the Devonian, D ; the Triassic, Tr; the Jurassic, J. The distinguishing markings of these areas will be learned by means of the lettering. The flexures of these rocks in the structure of the Wasatch Mountains are not all the usual up-and-down flexures ; there is, besides, an in-and-out series between and about the Archaean summits, as well as upon them. They may be traced by following the courses of the black Cambrian areas. Com- mencing at Ogden, there is first an eastward bend toward Weber, then a westward, back to the summit of the mountains ; then, all the formations are gathered into an east-west trough, or syncline, which heads through the Gap, the strata that lie in the Gap dipping from the north and south toward its center. The head, or western termination, of the bend passed the summit, disastrously to the extremity of the flexure. South of the Great Gap, the Cambrian and the rest of the formations lie around Clayton Peak 362 DYNAMICAL GEOLOGY. and Archaean No. 4 ; and then the Subcarbonif erous limestone (Cb 1 ) bends over the summit, saddle-like, with some outcropping Devonian along the middle. It is a complex system of zigzags in the great 30,000-foot pile of rock formations. From the range of strata involved, and their thickness, it is apparent that the making of the mountain was preceded by an accumula- tion of strata from the top of the Cretaceous down to the Archaean ; and that the strata were slowly formed in a subsiding area, or geosyncline, like the strata of the Appalachians. The relation of the Wasatch to the Uinta Mountains is learned by following the out- cropping belts from near Weber southeastward to Echo, and thence to the Uinta. The whole series of beds, from the Cambrian to the uppermost Cretaceous (the Laramie, Cr 4 , finely cross-lined), is here included. The dips are eastward 45 or more to Echo, which has Cr* either side, where they are 20, and then northwestward to the top of the Uinta ; there is hence a syncline at Echo, and an anticline at the broad Uinta summit, where the dip is 4 to 5 north and south ; the rock, Cb 2 , is the middle Carboniferous. Over the neck between the Uinta plateau and the Wasatch Eange, there is a large area of igneous rock (trachyte) lettered /(the initial of fire, or the Latin focus), apparently a consequence of the enormous amount of warping in the great pile of rocks. Two other smaller trachytic areas exist to the north in the same line. The Wasatch and Uinta regions were, therefore, involved in a common system of profound movements, in which were flex- ures and warpings, with fractures deep enough to let out melted rock. Moreover, the country east of the Wasatch participated in the warp- ing; for the Cretaceous beds occurring over it have high dips, and are portions of flexures, or of upturned masses, that have become isolated by the large amount of denudation which the country has undergone, the excava- tions being not now visible only because they became filled by the depo- sitions of the Eocene Tertiary. The Uinta plateau, on the landward side of the Wasatch, has some relation in position to the Cumberland Table-land on the landward side of the Appalachians. The great Uinta mass, 20 by 150 miles in area, is divided by deep fractures into a few blocks which are only slightly displaced, as well illustrated by Powell. Seventy-five miles south of Great Salt Lake, where the Wasatch Mountains proper may be said to end, there commences the series of "high plateaus," which extends south- ward to the borders of the Colorado Canon. This plateau region is one of great faults, of few gentle flexures, and of monoclinal uplifts, with intersect- ing canons as a result of its denudation. The rocks are the same that make the Wasatch and Uinta Mountains, except that large areas are covered with igneous outflows. The following cut (Fig. 336), by Powell, represents a portion of the plateau region north of the Colorado Canon, with its flexures sometimes passing into faults. The Colorado River flows in Marble Canon. The heights look small, but the fault at W. K., the West Kaibab fault, is 2000 feet high ; at E. K., the East Kaibab, 3000 feet ; at T., the Toroweap fault, 700 feet ; at HYPOGEIC WORK. 363 H., the Hurricane fault, about 1800 feet, 336. becoming 6000 at the Virgen Eiver. And some of the plateaus exceed 11,000 feet in height. The long range of bluffs to the eastward, commencing above the letter E., is that of the Echo Cliffs ; and the upward bend is attributed to a fault of 3000 feet (Button). Ascending the plateaus facing the Grand Canon region, the Carboniferous rocks are left behind, and a rise made over outcrops of Permian, Triassic, Jurassic, and Cretace- ous rocks. At W. K., and to the westward, the faulting is a downthrow of the block next west, while east of it the displacement is a downthrow of the block next east. These plateaus south of the Wasatch Mountains take the place of the mountains, being results of the same post-Cretaceous disturbance. Mr. King, in his account of the Wasatch Mountains, recognizes the principle that Ar- chaean forms of surface determined the po- sitions of lines of disturbance or uplift in mountain-making areas of later time, and influenced also the kind and amount of dis- turbance. He observes that the Archaean ridge which makes the flank and partly the crest of the Wasatch Range was the means of locating there, by mechanical resistance, the great flexures. In other parts of the same region, where there are no Archaean elevations, the disturbance resulted only in "high plateaus." He suggests that the Uinta plateau may have been thus located, although very little Archaean rock is now in sight about it. To the eastward of Utah, through Col- orado, along the Elk Mountains, the San Juan Mountains, and the Park regions farther east, there are other more or less independent ranges of contemporaneous origin, and they are continued interruptedly into the northern part of New Mexico. The narrow upturned belt at the eastern foot of the Front Range of Colorado, described, from the beds near 364 DYNAMICAL GEOLOGY. Denver, first by Marvine (1873), is of the Laramide system ; and it is con- tinued south through Huerfano County, into New Mexico along by the Eaton coal-field (C. S. Hills). Still farther south upturned Cretaceous beds extend along the trans-Pecos region of western Texas, and thence into Mexico. But the limits of the several ranges and their relation to the Laramide system need further study. The sketch in Fig. 337, from the west slope of the Elk Mountains, in Central Colorado, shows a sigmoid twist in the stratification of the rocks, the highest in the series being the Cretaceous ; the warping of the strata is strikingly exhibited. W. H. Holmes has sections of flexures and flexure faults of the Elk Mountains in the Hayden Expedition Eeport for 1874, two of which are closely like the form obtained by Daubree in his experiments (Fig. 326, page 351) . 337. Upturned strata of the west slope of the Elk Mountains, Colorado. The light-shaded stratum, Jura-Trias; that to the right of it, Carboniferous; that to the left, Cretaceous. Hayden's Report. Igneous ejections attended the mountain-making in many parts of the upturned region, from Wyoming southward, and some volcanoes may date from this epoch. 4. Tertiary Orographic Movements along the Pacific Mountain border. 1. The great geanticline, At the close of the Cretaceous period the latest beds lay at or near the sea level; and after the making of the Laramide mountain-chain the region was still but little above this level. During the Tertiary era following, especially after the Miocene period, a gradual elevation of the mountain region went forward ; and now, as the result, the same Cretaceous strata in some parts of Colorado are 10,000 to 11,000 feet above the sea. From this level the height slowly diminishes to 4000 feet and less near the Arctic coast and to twice this in Mexico. The region thus placed these thousands of feet above the sea level probably included the whole of the Pacific mountain border, from the line of the Mississippi Valley to the Pacific coast line, and outside of this line for one or more scores of miles. The vast geanticline was made without correspond- ing flexures of the rocks ; there were only minor local bendings, upturnings, and faults. It was a very slow movement upward, continuing probably into the Quaternary. That it made little progress in Eocene time is proved by HYPOGEIC WORK. 365 the existence during this period of large freshwater lakes over the summit of the mountain region ; for much rise would have made slopes that would have drained the lakes (Hayden). The Wasatch and Uinta Eocene basins of Utah and Wyoming, lettered with TFs and U's on the map (Fig. 335), were two of these lakes. Miocene lake basins, farther to the east, show that even in Miocene time the progress was slow. Contemporaneously, similar movements were in progress over the other continents : along the Andes, affecting half, at least, of South America; the Pyrenees, Carpathian Alps and a large part of Europe j the Himalayas and much of Asia. 2. The Rocky Mountain geosynclines. The geanticline, above described, had made little progress when local geosynclines, or subsidences, commenced over the summit region of the mountains. The areas of the fresh-water lakes, referred to above, were the sinking areas ; and the sinking went forward, and concurrent deposition' of beds, until the troughs contained strata of Eocene Tertiary 8000 to 10,000 feet in thickness the earlier half in the Wasatch epoch and the later in the Green River. After these Eocene basins ceased to subside, more eastern Miocene and Pliocene geosynclines were formed. Moreover, an epoch of upturning and plicating took place, both after the laying down of the Wasatch beds and of the Green River beds ; and of up- turning, in some places, after the close of the Miocene depositions. These were local disturbances apparently quite independent of the great geanti- clinal movement, which was also in progress. Igneous eruptions. During these Tertiary movements the greatest of igneous ejections occurred over the Rocky Mountain region from its summit westward. It is supposed that a large part of the volcanoes of the world had their birth at the close of the Cretaceous and during the Tertiary era. 3. Faults in the Great Basin and elsewhere. The Great Basin has many bare ridges, 3000 to 5000 feet above their bases, standing in the great area of lakes and alluvium-like islands in a sea. These ridges trend north- ward. There are outcropping crystalline rocks in some of the ridges, but the rocks, according to King, are mostly Paleozoic, except west of the meridian of 117^ W., within 100 miles of the Sierra Nevada, where Triassic and Juras- sic rocks occur. The beds of the ridges are more or less upturned, often in great anticlines or synclines, or elsewhere in simple monoclines; but the island-like isolation of the ridges prevents a study of their stratigraphic rela- tions. King suggested that the more western of the ridges were perhaps part of the Sierra system, which dates from the beginning of the Cretaceous period, or the close of the Lower Cretaceous ; and that the more eastern were perhaps post-Carboniferous in epoch of disturbance. Among the Basin Ranges, according to King, great anticlines characterize the Agui Range, the Promontory, Gosiute, Egan, Peoquop, and Toyabe ranges ; the Humboldt Range, although having a nucleal axis of Archaean ; the Pinon Range, in which the anti- 366 DYNAMICAL GEOLOGY. cline is stated to be a magnificent arch of Cambrian, Silurian, and Devonian ; the Little Elko, Cortez, Shoshone, Pah-Ute, and other ranges. The same flexed condition of the beds is mentioned by I. C. Russell as existing in the ranges of the Oregon part of the Great Basin. The ranges of the Great Basin have many faults as well as flexures, as described by Gilbert in 1876; and these faults are generally downthrow faults. The following are two of his figures ; they illustrate two ridges made up of blocks displaced as described. The dip and the downthrow faults are in opposite directions. 338. East. Fig. 338, section of Pahranagat Range at Silver Cafion, southern Nevada, scale Timpahute Range, west of the Pahranagat, scale y3 Jjj n . Gilbert, '76. Fig. 889, section of Gilbert, in view of the great displacements by nearly vertical and largely downthrow faults, designated the system of mountain-forming movements the " Great Basin System." He shows that the displacements are along old fault planes, and also along new planes of fracture made in the course of the Tertiary era, and later. Great displacements along old and new fault planes have been shown to have taken place also in the high plateaus of Utah and in the Uinta Mountains, others in the Wasatch, and still others in the Sierra Nevada, which are referred to the Great Basin System. The fact of such move- ments extending into recent time has been urged by Powell, Gilbert, Rus- sell, Le Conte, Diller, and others. The ridges of the Great Basin, made thus of upturned and plicated rocks, have been assumed to be each limited by faults, and to have undergone up and down movements, and variously tilting displacements, and thus to have become in effect " monoclinal orographic blocks" in the " Basin System," each block making by itself a monoclinal mountain, even when not so in its bedding (Russell, 1885). In the ideal sections made to illustrate this hypothesis, the wide intervals of alluvium (that is, of buried and concealed rock) are represented as underlaid each by a block at lower level, or by the subterranean continu- ance of one sloping ridge to the next ; and the actual flexures or lines of bedding have been omitted, and monoclinal lines substituted. They are intended to exhibit the sup- posed structure. But until the stratigraphy of the ridges of the whole basin shall have been studied and sections of them represented, and the relations of each ridge to those lying on the same northward or northwestward line of strike shall have been thoroughly investigated, general stratigraphic conclusions cannot be safely drawn. HYPOGEIC WORK. 367 5. Foreign Examples of Tertiary Mountain-making. 1. The Alps. Among foreign mountain regions those of the Jura Mountains and the Alps the two combined in system have been most carefully studied. The former are much like the Appalachians in flexures, as first pointed out by H. D. Rogers. The Alps have far greater complexity. The able work of Heim on mountain-making, based on his study of the Toedi-Windgaellen group, gives a full exhibition of the structure in that part of the Alps, and lays down many principles in orography. The section on page 102, showing overturn folds, is reduced from one of Heim's sections. One of the overthrust folds in the region has put the beds upside down over an area of 450 square miles. 50,000 feet of formations of the Jurassic, Cretaceous, Eocene Tertiary and Miocene Tertiary, were upturned at the close of the Miocene period. Another remarkable section of overturn flexures in the Alps, worked out by Kenevier, is represented in Fig. 340. The Dent de Morcles stands between Profile of the Dent de Morcles. Tert. 1, Nummulitic Eocene Tertiary ; Tert. 2, Upper Eocene Tertiary, called the Flysch ; Cret. 1, the Neocomian or Lower Cretaceous; Cret. 2, theUrgonian, a higher division of the Lower Cretaceous. Scale, -K^TH for height and length. Renevier. Martigny and Bex on the east side of the Ehone. Cretaceous and Tertiary strata, making the top of the mountain, here lie upside down on Tertiary and older formations. One of the Tertiary formations, the Upper, is folded over on itself. The overturn is indicated in the figure by the lettering. The Cretaceous strata below the plane of the overturn are absent ; but above it there are two strata of the Lower Cretaceous. It is probable that Jurassic beds once made the top, and have been removed by denudation. As stated above, the Jura Mountains, northwest of the Alps, are part of the Alps mountain system. The following section (Fig. 341) illustrates the fact that the flexures are overthrust in a northwest direction, like that in the Dent de Morcles, as if the thrust-force came from the southeastward. This direction is not, like that in the case of the Appalachians, from the ocean, but totvard it. The thickening or the expanding of the beds in the summit of a steep 368 DYNAMICAL GEOLOGY. flexure, and the thinning, even to removal, of those of the flanks in close- pressed overthmst flexures, are two important points well illustrated in Figs. 118 and 119 on page 110, and in Fig. 120, representing the resulting 341. Section of the Jura Mountains, along a line extending northwestward from Geneva through St. Claude to Chaux du Dombiel. 1, Trias ; 2, Lower Jurassic ; 3, Upper Jurassic ; 4, Cretaceous ; 5, Tertiary. Scale, rcsW- P. Choffat, in Heira's Mech. Geb. 342. flexure-fault. Fig. 342 has a still greater displacement along the plane between the anticline and syncline, with a complete separation of the originally continuous beds, as the numbers on them show. This thinning and faulting are due to the friction between the overlying and underlying flexures during the overthrust move- ment. The facts teach that a regular unfaulted overturn flexure, like that represented in the part to the right of Fig. 91 (6), on page 103, is only an A flexure-fault from the Alps. Heim. ideal form. The Alps had been the scene of earlier mountain-making after both the Archaean and Carbonic eras. The chain of the Alps includes, therefore, (1) Archaean, (2), post-Carbonic, (3) post-Miocene ranges; and the Juras belong with the last in time. The proof that an upturning took place after the Carboniferous or Permian is shown in Fig. 340 ; the Jurassic beds (which include, at bottom, the Lias) rest unconformably on the Carboniferous, evincing that a time of upturning had intervened. In the Oriental Alps, the great upturning was post-Cre- taceous instead of post-Miocene. 343. Post-Nummulitic upturning in the Himalayas. La Fouche. 2. Post-Nummulitic upturning in the Himalayan Range. In the Upper Indus Valley, Middle Tibet, in the district of Zanskar, south of the Indus, Nummulitic limestone (Eocene Tertiary) constitutes the summit of a peak of the Singala, having a height of 19,000 feet. In the section (Fig. 343) the blocked area is the Nummulitic limestone, a blackish fetid rock ; the HYPOGEIO WORK. 369 folded dotted layers below are quartzytes, and the beds below, shales. (La Fouche, India Survey, 1888.) 3. Arctic upturned rocks. Flexures as a result of lateral pressure occur in the Arctic regions. On Grirmell Land, from Scoresby Bay to Cape Cress- well, in lat. 82 40' N., slates, limestone, grits, and quartzytes are in sharp folds, and often vertical, with the strike E.N.E. Feilden & De Ranee on the results of the Sir George Nares Expedition in 1875-76. For other examples of erogenic movements see pages 534, 808-812, under Historical Geology. CONCLUSION. Orographic work has been carried forward, in general, by means of flexures, fractures, and slips or faultirigs along fractures ; and the faults have largely been flexure-faults, that is, have been made in connec- tion with the production of more or less pronounced flexures. SUBORDINATE EFFECTS ATTENDING OROGRAPHIC MOVEMENTS. Among subordinate orographic effects are first, those incidental to the friction, and the heat thereby produced, namely : (1) part of metamorphism, (2) of vein-making, and (3) of volcanic phenomena subjects already con- sidered. Second, those incidental to the pressure : these are (4) variations in the characters of flexures ; (5) distortions of beds and of fossils ; (6) slaty cleavage or foliation; (7) joints. Third, (8) earthquakes. 1. Effects Incidental to the Pressure. 1. Variations in flexures. The characteristics of flexures have already been illustrated and explained (page 101). The pressure producing them encounters unequal resistance from inequality of mass in the pile of strata along the axis of the area of disturbance ; from unequal consolidation, or firmness, or rigidity, in the beds ; and also from friction against the floor of rock beneath. For these reasons flexures of the ordinary kind always have the ridge-line inclined, and are irregularly distributed along an area of disturbance. The Wasatch Mountains (Fig. 335) illustrate the influence, on the flexures, of the floor of rock underneath the moving strata, and show that a flexure may be made with its axis in the line of the pressure and be thrust forward end foremost. The minor flexing or wrinkling of beds, not uncommon in the fine slaty rocks and schists, is often occasioned by unequal yielding to pressure in the beds, unequal rigidity, unequal contraction ; and it may also come from feeble oscillations in the action of the moving force, and from the action of gravity on the highly upturned or vertical beds. 2. Distortions of beds and their fossils. The beds subjected to the enormous pressure were more or less yielding. Argillaceous strata are soft DANA'S MANUAL 24 370 DYNAMICAL GEOLOGY. and become compressed in the direction of the pressure, and extended at right angles to it; and other earthy beds have suffered more or less in a like way. But strata of quartz sands, not firmly cemented, have accommodated themselves to the pressure in part by rearrangements of the grains ; and those of limestone, and hard quartzyte, brittle rocks, mostly by fracturing, displace- ment, and recementation. The distortions of fossils vary according to the relation in position be- tween the planes of bedding or cleavage of the rock, and the axial plane at right angles, or nearly so, to the direction of pressure. The inequalities in the pressure and in the varying resistances to motion were a cause of a warp- ing of the beds on a large scale, which had its effects. Hence stretchings, slippings, and contractions of fossils are common in such beds. Some examples are shown in the following figures from a paper by D. Sharpe (1847, Q. J. G-. Soc.}, illustrating cases observed by him in a slate rock in Wales. They repre- sent two species of shells, the Spi- 344. rifer disjunctus (Nos. 1 to 4) and the Spirifer giganteus (Nos. 5 to 8). No. 1 is the natural fprm of 8. disjunctus ; the others are dis- torted. The lines zz show the lines of cleavage in the slate: 2 lay in the rock inclined 60 to the planes of cleavage, and is short- ened one half ; 3 lay obliquely at an angle of 10 or 15, and short- ened above the middle and length- ened below it ; 4 is a cast, the upper part pressed beneath that shown, while the lower is much drawn out ; 5 is like 3, the angle with the cleavage-plane being less than 5, and the lower part has lost its plications by the pressure and extension ; 6 has a similar angle to the cleavage-plane, but a different position ; 7 intersects the cleavage-plane at only 1, and its lower part is very much elongated. Compression, a sliding of the rock at the cleavage- planes, and more especially a spreading of the rock itself under the pressure, are the causes which have produced these distortions. All fossils are liable to become similarly misshapen under the same conditions. 3. Foliation, slaty structure. Koofing slates exemplify cleavage-struc- ture, or foliation. They are most common on the outskirts of regions of disturbance. Slaty cleavage often graduates into the foliated structure of hydromica and mica schists. The fact that slaty structure is not coincident with the bedding-planes was explained by Sedgwick in 1835, from observa- tions in Wales. Sorby first pointed out (1849) that the structure was due to the forcing of all flattened and linear particles into parallel planes, approxi- mately perpendicular to the pressure ; and that all air-cavities and particles of moisture are flattened likewise. He sustained his conclusions by. micro- scopic examinations, and by subjecting to pressure clay and scales of oxide of iron. Tyndall rendered beeswax, clay, and other substances, laminated HYPOGEIC WORK. 371 by simple pressure; and later Daubree, who experimented with clay and scales of mica, obtained a perfect schistose structure. The rolling and ham- mering of metals result in a laminated texture, which fracturing or acids may reveal, when not otherwise visible ; and several fine examples are fig- ured by Daubree in his excellent work on Experimental Geology. Mountain-making was going forward, and the work done was therefore on a large scale, producing at one effort slaty structure over areas of hundreds of square miles, with great uniformity of direction and high angle of pitch. Sedgwick recognized the approximate coincidence of the strike of the slates with the strike of the beds, or rather, as Professor Phillips stated it, with the direction of the main axis of elevation. The uniformity of product and evenness of surface are a consequence of the fineness and evenness of grains of the original argillaceous formation, and the regularity of the long-con- tinued pressure ; but partly also of the moderate degree of heat during the action of the pressure. Further : pressure has been proved to have produced a foliated, and even a schistose, structure in the granite-like rock, of igneous origin, called granulyte, and also in augitic and other igneous rocks. A slaty formation often contains fossils, and these indicate, to some extent, the degree of compression and distortion which the beds containing them underwent under the pressure. The fossils in Fig. 344 are from a paper on slaty cleavage. This subject has been treated mathematically by Professor Haughton (1846, 1857); and more recently by A. Harker (British Association, 1885). Slaty cleavage, or that characterizing roofing slates, passes gradually into the foliation of hydromica schist and mica schist, and thence into that of gneiss and gneissoid granite, suggesting that the latter may be due in these rocks to pressure. This has been confirmed by experiment and observation. But geological observation is required to settle any doubts that arise, rather than the microscope. In general, the foliation of mica schist and gneiss is not a result of pressure, but, on the contrary, of the original bedding of the formation. The evidence of this often appears in the occurrence of large variations in strike and dip in the planes of foliation, instead of the high angle and evenness character- izing slates ; in flexures of the sheets of rock, anticlinal or synclinal ; and in alternations of the sheets with those of limestone or other kinds of rock, such alternations hi connec- tion with low dips or flexures being good evidence that the sheets are true beds. Only the finer kinds of metamorphic rocks argillyte and hydromica schist often lose their bedding by the substitution of the cleavage structure through pressure. 4. Joints. Joints in rocks (see page 111) have various methods of origin. They are in part due to slow-acting pressure on the outskirts of a region of disturbance. The pressure may act with little or no warping of the beds. That this is often the case is indicated by the general parallelism in the joints. But in other cases warping or torsion is strongly marked, as Daubree has shown. Daubree has illustrated the effects of torsion on the courses of joints by subjecting plates of ice to the action. He obtained, as one of his results, with a plate nearly a yard long, the fractures shown on a much reduced scale in Fig. 345. Fig. 346 shows a portion of one of the plates one fourth of the natural size. (It is from a photograph, and hence 372 DYNAMICAL GEOLOGY. 346. 345. the reflections from the surfaces of fracture give a false appearance of ridges along the fractures.) Daubree draws attention to (1) the approximate parallelism of the lines, and yet their slight divergence ; (2) the crossing of one set of lines by an- other nearly at right angles, anti-parallels, as he calls them ; (3) the fact that the lines are in groups ; (4) the fact that joints may be an instantaneous effect ; (5) the very important fact that the force pro- ducing the joints did not act at right angles to either set, but at the extremity of a bisectrix to the angle of intersec- tion of the two sets ; and (6) the fact that the slower the action of the force and the larger the plates, the nearer the approach to parallelism between the lines in each set. Fract- ures made by torsion might be left open when those from direct pres- sure would remain closed. Other instruc- tive figures are given in his work on Experimen- tal Geology. Joints may also be due to the vibrations of earthquakes (Crosby), and to changes of temperature (pages 260, 264). 2. Earthquakes. An earthquake is a series of vibrations begun in some region of local dis- turbance in the earth's crust, and propagated upward and outward from this place as a center. Slight tremors may be produced by falls of large rock- masses, where undermining has been carried on. But true earthquakes come, for the most part at least, from one or the other of the following sources of disturbance : (1) Vapors suddenly produced, causing ruptures and friction; or, com- monly, (2) sudden movements or slips along old or new fractures. Earthquakes due to the former of these methods are common about vol- canoes. At the Hawaiian Islands, shakings that are destructive over the island of Hawaii at the moment of some of the more violent eruptions do Lines of fracture produced in a plate of ice (GG) by slight torsion, (x ^ a .) Portion of a plate of ice showing its fract- ures (x|). From a photograph. HYPOGEIC WORK. 373 not often affect the island of Oahu, a depth of 500 fathoms of water, the least depth between the two islands, being sufficient to stop off the vibrations. Milne states that Japan, a country noted for volcanoes, averages, some years, an earthquake a day ; and that in two years, in north Japan, 154 out of 387 shook an area of less than 50 miles, and a few of the larger shocks, an area of about 150 miles. Earthquakes of the second mode of origin may occur in all regions, vol- canic or not. They have their origin mostly in the vicinity of mountain regions where old fractures most abound. The vibrations may be begun in a slip of a few inches, or feet, but when there has been a succession of slips, up and up for 10,000 feet and more, as in the faults of the Appalachians, earthquakes of inconceivable violence must have resulted. Earthquake vibrations have been supposed to be due to wave-like movements in the interior liquid mass of the globe, and Professor A. Perrey of Dijon concluded that the greatest number of earthquakes occurred at the season of the syzygies in each lunar month, synchronous with the tides in the ocean. But if the earth is solid throughout, the facts have another explanation. The observations of Professor W. H. Mies on the gneiss of a quarry at Monson, Mass. , show that even the solid rocks are in some places under a strain ; for he states that bendings, sudden fractures, and expansions of the rock often take place; masses, before their ends are detached, become bent upward at middle ; and one mass, 354 feet long, 11 wide, and 3 thick, was an inch and a half longer after it was detached than before, showing a strain which was greatest in a direction from north to south an effect due to compression by the pressure the rocks had been subjected to, and a consequent expansion in a transverse direction. All are familiar with the crackling sounds occurring at intervals in a board floor of a house, arising from change of temperature, especially in winter in a room that is heated only during the day ; and with the more common sounds of similar char- acter from the jointed metallic pipe of a stove or furnace, given out after a fire is first made, or during its decline. In each case, there is pressure or tension, accumulating for a while from contraction or expansion, which relieves itself, finally, by a movement or slip at some point, though too slight a one to be perceived ; and the action and effects are quite analogous to those connected with the lighter kind of earthquakes. The earthquake of Lisbon, in 1755, which threw down the greater part of the city, and in six minutes caused the death of 60,000 persons, disturbed an immense area, it being felt at Algiers and Fez as severely as in Spain and Portugal, in the Alps, Great Britain, on the Baltic, and in northern Germany. The effects from sea- waves were of wide extent, but such waves may be propagated across an ocean from the vibrations of a coast region. An earthquake on the 4th of January, 1843, reported upon by Professor H. D. Rogers (1843), "was felt from the seacoast of Georgia and South Carolina to and beyond the western frontier military posts, and from the latitude of Natchez to that of Iowa, a distance in each direction of about 800 miles ; and there are reasons," Professor Rogers adds, "for believing that its actual extent was much greater. Its course was from N.N.W. to S.S.E., and its rate of progress about 2800 to 3000 feet a second, and equable in rate. The Charleston (S.C.) earthquake of August 31, 1886, which threw down many buildings in the city, was felt from the Carolina coast, Georgia, and central Florida, northward to southern New England, and across New York to Ontario in Canada, and westward to eastern Louisiana, Arkansas, Missouri, and Iowa, an area 800 miles wide by 1000 miles from north to south. Its course was the reverse of that of 1843. It was scarcely appreciable in sea disturbance. 374 DYNAMICAL GEOLOGY. Volcanoes stand on lines of fractures in the opening of which their existence began ; and subsequently, through geological time, slips up or down may have occurred along such fractures in the earth's uneasy crust, independent of local action, producing earthquakes, and, perhaps, also initiating eruptions. The Mediterranean area is one of the earth's fire regions, from its eastern to its western limit, and its borders are noted for the relative frequency of earthquakes ; and these earthquakes, in the majority of cases, are independent of action in the volcanoes of the era. This is true also, according to Milne, of the greater earthquakes of Japan. The New Zealand Tarawera eruption of 1883, which blew out with explo- sive violence for a day or two, was followed, three days after it had subsided, by an outbreak in White Island, an active volcano in the Bay of Plenty, and, two months later, by a violent eruption on the island of Ninafou in the Tonga group. The three volcanic regions are on the same island line of the ocean, the northeast or New Zealand line, which is one of the most marked in the Pacific. It may be that this succession of disturbances was due to a slight movement from north to south along the old fracture-plane, through the opening of which the range of islands began its existence. The -central region of an earthquake vibration, which may have con- siderable breadth or length, or have the course of a long fissure, is called the epicentrum. The rock-waves move off from it in all directions, but often most forcibly in one. The waves are: (1) waves of compression, or conden- sation, in which the vibrations are normal to the origin, or in the direction of the movement of the wave ; and (2) waves of distortion, or transverse waves. The sounds of earthquakes are attributed by Milne to preliminary tremors preceding the principal shock, which have the more rapid movement required to produce sound. The amplitude of the wave varies from less than a millimeter to possibly a foot. But destructiveness depends more on rate of vibration than on am- plitude. Milne observes that the greater the initial impulse, the greater the speed of propagation ; and, as the propagation widens radiately, the velocity of propagation decreases, the period usually becoming larger. C. Davison (1891) traces several earthquakes of Great Britain to slips along faults. He observes that from the central portions of the slip-area will come, as a rule, the vibra- tions of largest amplitude and longest period, and from its margin, and especially toward the surface, minute vibrations of a period so short that they 'may be perceptible only as sound. He thus explains the fact " that the sound-area is not concentric with the dis- turbed area, and the sound- focus is nearer the surface than the rest of the seismic focus " ; and also, "the fact that, in great earthquakes, the sounds are heard only within a compara- tively small area immediately around the epicentrum." Liability to slips, and therefore to earthquakes, diminishes with the progress of time. Kinds of rocks have great effect on the propagation. Milne obtained in Japan, for velocities of propagation, from 200 feet per second to 630 feet ; Mallet obtained, for sand, a rate of 825 feet, and for granite, of 1665 feet; Newcomb and Dutton, in the Charleston earthquake, made out a rate of 17,000 feet per second, without any indications of variation in the speed ; H. L. Abbott in his observations on explosions at Hallet's Point in 1876, HYPOGEIC WORK. 375 4500 to 20,000 feet per second ; and Fouque found the velocity in granite 9200 feet per second. The position of the epicentrum is ascertained by noting the-direction of throw of over- turned columns, walls, houses, the converging lines pointing to the region of the surface vertically over the epicentrum. An oblique thrust is most effective in overthrowing objects ; and the particular belt-line around the central region along which the waves are most destructive is called the meizoseismic curve, and lines of equal disturbance, isoseis- mic curves. Such curves are far from circles. By means of evidence from fractures in walls and overturned objects, R. Mallet in- ferred the angle of emergence of the wave, and so calculated the depth of the center of disturbance. From 26 observations of the Neapolitan earthquake of 1857 he deduced a depth of 6^ miles. C. E. Dutton, in his paper on the Charleston earthquake, assumes that the total disturbance is inversely as the square of the distance from the center of disturbance. By noting, in the Charleston earthquake, the circle about the epicentrum at which the total effect diminished most rapidly on going from the epicentrum, he deduced depths of 8 and 12 miles for two distinct centers of disturbance. The instruments by which the earthquake movements are detected (seismoscopes) , measured (seismometers^ , and recorded (seismographs), are of many kinds. Those which experience in Japan has proved to be most accurate are the so-called Duplex pendulum ; the Bracket seismographs of Chaplin, Ewing, Gray, or Milne ; and conical pendulums. The geological effects of earthquakes are small, while those of the causes which produce earthquakes are large. Vibrations loosen rocks and may tumble them down precipices, as they tumble down houses and walls. Occasionally they produce some rotation in the objects moved where the object is not equably attached below. They may fracture the rocks and ground in the re- gion of greatest disturbance. They often occasion the drying up of springs. In Calabria, in 1783, fissures were made that were over a mile long, 100 feet wide, and 200 feet deep. In the Charleston earthquake of 1886, and also in that of 1892 at Quetta, in British Baluchistan, described by C. Davison, railway lines were bent ; and in the latter case, on removing the bent rails for repair, the new lines had to be cut 2| feet shorter than the old ones, owing to a permanent displacement. But these rending effects and the uplifts, and other results attending them, are effects rather of the deep-seated cause of the vibration and the fracturing. Besides these effects, earthquakes may destroy life in the sea, by impact, as a blow on the ice of a pond will stun or kill the fish. They may also throw the ocean over the land in waves of 30 to 100 feet, carrying in the animals of the sea, and, in these modern times, man's boats and ships, besides lifting and bearing far inland sea-bottom rocks and sand, and great masses of coral rock on the shores of coral islands (page 222). Further: if a mountain-system of the length of an America were making, like the post- Cretaceous Laramide System, and a like system cotemporaneously in the other America, sea-borders, continental seas, and land-borders the world over might be mostly stripped of life by earthquake waves. Or, if the mountain systems in progress were of less extent, like the post-Paleozoic, a hemi- sphere might experience the devastations, and austral land-borders and sea-borders escape. 376 DYNAMICAL GEOLOGY. ORIGIN OF THE EARTH'S FORM AND FEATURES. This embraces first, the origin of the shape of the earth's mass ; second, the origin of continental plateaus and oceanic depressions, and of all move- ments in the earth's crust through geological time not involving erogenic work ; and, third, the origin of the movements producing the upturning of formations and the making of mountains. The first of these subjects, geogenic work, pertains to astronomy. The movements referred to under the second, by which wide changes of level have occurred without special orogenic results, except displacements along old or new fracture-planes, have been termed by G-. K. Gilbert epeirogenic, or continent-making (1890). The work included under the third head is orogenic. 1. GENERAL CONSIDERATIONS BEARING ON THE EARTH'S FORM. 1. Solidification of the earth. The earth solidified from the center out- ward. This conclusion is established on the evidence that pressure raises the fusing point of rocks. The globe was, therefore, never in a state of complete liquidity. According to Clarence King, experiments made for him by C. Barus with reference to the question as to the earth's rate of cooling (see page 1026), lead collaterally to the conclusion that the depth of the liquid exterior of the globe has at no time exceeded 50 miles. The study of meteorites has led some astronomers and writers on the constitution of the globe to the opinion, in view of the iron in these bodies, and the fact that their place in the solar system is to a large extent near that of the earth, that the earth's interior con- sists, for the greater part, of iron. This view is favored, also, by the high percentage (10 to 14) of iron oxide in most igneous rocks ; the existence of much native iron in doleryte at Disco Island, Greenland ; and the occurrence of the greatest of iron-ore beds of the world in the oldest rocks, the Archaean. Platinum, gold, silver, and copper are heavier metals ; but it is remarkable that they are not brought up among the constituents of erup- tive rocks, as iron is, but are obtained from the supercrust and its veins : as if these metals, in consequence of being in vaporizable combinations, or those of comparatively little spe- cific gravity, were near the surface of the fused globe, while below these were the iron and whatever, under the conditions, could form alloys with it. If the earth is two thirds iron, or iron to within 500 miles of the surface (without much increase in the density of the iron downward), and the rest were made chiefly of basaltic, or dolerytic, material, it would have about its present specific gravity, 5-5. The complete solidification of the earth is held to be its present condition by most physicists who have recently discussed the subject. This implies that the crust that was formed over the surface of the liquid stratum by cooling had continued to thicken until the whole was solid. The evidence favoring the earth's essential solidity has been obtained by investigating mathemati- cally the amount of deformation which the sphere, if a liquid mass enveloped in a thin crust, should undergo during its revolution ; and also the effect of such tidal movement in the earth's mass on the height of the oceanic tides. Kelvin concludes, on these grounds, that the earth must have an effective rigidity at least as great as that of steel (1862, 1872). G. H. Darwin has HYPOGEIC WORK. 377 sustained the same conclusion, stating that " if it were true that the earth is a fluid ball coated with a crust, that crust must be of fabulous rigidity to resist the tidal surgings of the subjacent fluid" (1888). At the same time, according to the same authority, the weight of the water of a high flood-tide probably occasions, owing to the elasticity of the crust, " a local elastic yield- ing along the coast-line of continents"; and " there is reason to believe that such flexure has actually been observed by a delicate form of level on the coast of the Bay of Biscay." Newcomb favors the same conclusion in a paper discussing the cause of the periodic variations of latitude (1893). 0. Fisher, of Cambridge, England, questions the above conclusion from the tides (1892). Basing his mathematical calculations on an investigation by Darwin of the tides upon a yielding earth according to the canal theory, he obtains the result, that the height of the tide for a liquid earth would be only a fifth less than that for a rigid earth, and suggests, as the difference is so small, that the existing tides may have just the height appropriate to a liquid interior. He observes, further, that the heat generated within the earth by the tides in the earth's mass from their commencement calcu- lated by Darwin to be sufficient " to give a supply of heat, at the present rate of loss, for 3560 millions of years " would have been only to a small extent expended or wasted, and that, through convection currents, it keeps the liquid layer in fusion, and prevents the crust from growing thicker. Other considerations have led Fisher to make the thickness of the crust about 18 miles. The conclusion of Fisher is objected to by G-. F. Becker, on the basis of calculations which lead him to the conclusion that "for a fluid earth the canal theory and the equilibrium theory give the same result, viz.: no relative tide." He adds, that "on any theory of the tides, the ex- istence of semi-diurnal tides indicates an earth presenting great resistance to deformation" (1893). 2. Earth-shaping. Whether solid to the surface or not, the earth is believed to be so far fluid-like in its mass as to admit of adjustments to gravitational pressure through molecular flow, if not through a liquid layer, and to owe its shape primarily to the principle of gravitational equilibrium, as if liquid. This view of adaptation to gravitational pressure was rec- ognized geologically by Herschel in his Appendix to Babbage's Ninth Bridge- water Treatise (1837), where he attributed changes of level to "changes in the incidence of pressure on the general substratum of liquefied matter which supports the whole," and argued therefrom that the rise in level going on in Scandinavia might be caused by the accumulation of sedimentary deposits over the adjacent ocean bed. The earth's interior liquidity was then gen- erally admitted. In 1888, C. E. Dutton proposed the term isostasy for " the condition of equilibrium to which gravitation tends to reduce a planetary body irrespective of whether it be homogeneous or not," that is, whether solid to the surface or partly liquid beneath it, and whatever its constitution. The rate of adjustment to changing load would necessarily be very slow in a solid globe, in which 'it could take place only through molecular flow in 378 DYNAMICAL GEOLOGY. the mass, while it might be comparatively rapid if a liquid layer existed beneath a thin crust a flotation crust, as it has been called. Darwin has remarked that through molecular movements the earth's spheroidal form might change with change of rotation. But what is the minimum limit in a solid globe, to rate of adjustment that is, to the rate at which resistances from cohesion and other causes can be overcome no known facts have even approximately indicated. Effects should, in any case, lag behind the cause of change, whether they are those from the deposition or removal of a load. There are, however, facts that seem to imply a somewhat easy adjust- ment. Many low coasts over which sediments are borne to the sea border are known to be slowly sinking ; as, for example, the coast of New Jersey, where the rate, according to G. H. Cook, is two feet a century. This sink- ing, and that of other parts of the Atlantic border, is attributed by Cook to gravitation in the sediments. W. J. McGee, in a paper of 1892, has brought together many facts from various coasts, mostly adjoining the mouths of rivers, bearing in the same direction. On the Netherland coast, the rate of sinking, according to Girard, is 0-09 to 0-75 meter per century, and 0-26 meter since 1732. But actual sinking is not a legitimate isostatic effect. The subsidence on such coasts corresponding to the amount of contributed sediments (not exceeding it) is not indicated by the amount of sinking, for the sinking is in excess of it. Other facts are more decisive. A boring on the southeast coast at Atlantic City, 1398 feet deep, extended through beds, as stated by J. C. Smock, which were proved by the fossils to be Miocene ; Turritella plebia occurring, according to Heilprin, at 450 feet, and Perna maxillata at 760 feet, of which depth 265 feet are surface gravels and 265 beyond are of doubtful reference. But at Asbury Park and Ocean Grove, farther north, wells afforded the Upper Greensand with Terebratula Harlani and other Upper Cretaceous fossils at a depth severally of only 270 and 280 feet below tide level, and the Lower Greensand at 365 and 382 feet. The facts indicate a very slow rate of subsidence at Asbury Park since the Cre- taceous period, and much less slow at Atlantic City, which is 80 miles south of Asbury Park and only 40 from the north cape of Delaware Bay. A boring on the coast of Texas passed through 3070 feet of shore deposits, without reaching, according to the investigations of G. D. Harris, beyond the Miocene. The deposits down to a depth of 458 feet are pronounced Quaternary. Beyond, to the 1511-foot level no Tertiary fossils were found and all of them may still be Quaternary. Between 1511 and 2153 feet, the deposits were Upper Tertiary as shown by fossils ; and between 2153 and 2920 feet, Upper Miocene. In the lower 150 feet, clays and sands were found without fossils. Similar facts are reported from the delta of the Ganges and other regions. These proofs of rather rapid subsidence along coasts are regarded by many as not inconsistent with the idea of a solid earth. Others have used them as strong evidence of a thin notation crust over liquid rock. But a "flotation crust" has its difficulties. The fact that there are high mountains anywhere is one of them. Against this objection it is urged that HYPOGEIC WORK. 379 mountains may have great cavities beneath them, through a parting and open- ing in the crustal terranes underneath, when they were elevated ; and it is stated in corroboration that by means of the plumb-line it is proved that the Himalayas have not the density of a solid mass. So also some volcanic peaks have been proved by pendulum experiments to be hollow. If volcanic mountains generally were shells over a cavity that was emptied in making them, the fact that they could stand on a thin crust would be no marvel. But the pendulum experiments of E. D. Preston at the Hawaiian islands have shown that this is not so. He found, in 1892, that Haleakala, on east Maui, 10,000 feet high, has a density of 2-7, or that of the mass of rocks at the surface ; and that Mount Kea, on Hawaii, nearly 14,000 feet high, while hollow above, the density there being only 2-1, has a density below of 3-7 (page 290). Yet these mountains stand, and, no doubt, under adjusted gravitational pressure; but how so, if on a thin crust, is an unsolved mystery. Isostasy is earth-shaping in its action, without being mountain-making. It has been in all time conservative of existing conditions of equilibrium. Subsidences made by loads have caused elevations somewhere around the subsided region; but the mean level, according to the principle, must have been retained. Loads over the bed of a Mexican Gulf should cause, in accordance with it, a subsiding, but not a deepening, for the subsidence just equals the load ; and on the border of the ocean they should cause a subsid- ing of the coast region, and not a sinking; for the subsiding could not exceed the filling contributed. The ice of the Glacial period, which covered a large part of northern North America and Europe to a depth of one or more thousand feet, was a load laid over the surface by moist aerial currents ; and to this load has been attributed by Jamieson (1865), Warren Upham, and others, the succeeding subsidence of the same glaciated regions, or that of the Champlain period. (See further, page 1020). 3. Continental plateaus and oceanic depressions. According to the prin- ciple of gravitational equilibrium, the earth's greater unevenness of surface, exhibited in the existence of oceanic depressions and continental plateaus, should be an expression of some difference in the density of the rocks. Perhaps the fact that the prevailing rocks of the oceanic volcanoes are basaltic, and of the continental, andesytic and trachytic, explains how it is that the oceanic crust is made the denser. The difference in the mean den- sities of the basaltic and andesytic rocks is about one tenth. The depres- sions, on this view, were made in the earth's cooling. This origin of the oceanic basins was suggested in 1860 by Archdeacon J. H. Pratt, in his memoir on the Figure of the Earth, where he attributes the existence of continents and these basins to unequal contraction, refers the formation of mountains to lateral pressure, and concludes that " the crust beneath the oceans is of greater density than the average portions of the surface" ; that is, that where the contraction was greatest the density of the rock material below is greatest, and proportionally so. 380 DYNAMICAL GEOLOGY. Since the mean height of the present continents is about 2000 feet, and the mean depth of the oceans 12,000 feet, and since the continental areas were already outlined and partly emerged, during later Archaean time, this mean depth of the oceanic depressions must also have been then acquired; and only an addition of 1500 to 2000 feet was needed to give the continents their present mean altitude. Of this, more than one half was added in the Tertiary and Quaternary. 2. OROGENIC WORK, OR THE MAKING OF MOUNTAINS. 1. In ordinary mountain-making, the rock material to be made into the mountain range has comprised a thick, conformable series of sedimentary strata, resting upon an uneven floor of upturned and usually crystalline rocks which were part of the underlying earth's crust. The Appalachian and Laramide strata were laid down on an Archaean floor; the Palisade beds of the Triassic, from New York southwestward, on one that was partly Archaean and partly consisted of Archaean and Cambro-Silurian ter^ ranes combined. The great facts to be explained in a theory of mountain-making relate (1) to the preparatory geosyncline or trough and its load of strata for the mountain structure ; (2) to the mountain-making events ; the upturning, flexing, and faulting of the strata, and all other effects of the movements in progress. On any theory of origin, such mountain ranges are syndinoria, as they have been termed by the author, from the Greek for syndine, and opos, mountain, they having had their beginning, as first recognized by Hall, in a preparatory geosyncline of accumulation. The geosyncline occupied the area of the future mountain range. It was slowly formed, while the crisis of upturning was relatively short. For the Appalachians the geosyncline, judging from the thickness of the included beds, had a maximum depth of 40,000 feet; for the Laramide Kange, north of Montana, 34,000 feet (Mc- Connell) and for the Wasatch portion, 31,000 feet (C. King) ; for the Alps, at the close of the Miocene, 50,000 feet (Heim) ; for the Australian Alps, 35,000 feet (Hector) ; for the Palisade ranges, 3000 to 5000 feet. The subsidence in the case of the Appalachian Range occupied all of Paleozoic time ; of the Wasatch Range and other ranges of the Laramide system, all of Paleozoic and Mesozoic time, which means many millions of years for each. Again, there is the remarkable fact that the subsidence has not always been continuous, but sometimes alternated with emergences, or ceased for long periods. In the case of the Ouachita Mountains, Arkan^ sas, whose history runs parallel with that of the Appalachians, there was a cessation through the whole of the Upper Silurian and Devonian, for these eras are unrepresented by rocks. Moreover, the area of the geosyncline, as the deposits show, varied, as the ages passed, in width ; varied in the posi- tion of the belt of maximum subsidence, from one side to the other, or from one part to another ; varied in the depth of water in which the deposits HYPOGEIC WORK. 381 were made, and in the courses and character of the transporting currents and waves. Further, the making of the geosyncline must have been attended in each case by a pushing aside of the rock material in the earth's mass existing beneath it, and an upward bulging, or a geanticline, over the region adjoining on one side or the other. The more prominent theories of mountain-making now current are (1) the Gravitation Theory and (2) the Contraction Theory. 1. The Gravitation Theory. The Gravitation Theory was brought forward in its simplest form by James Hall in 1859. According to it, the making of the preparatory geosyn- cline, in the case of the Appalachians, was due to the gravitation of the accumulating sediments, in accordance with the principle explained by Her- schel, whose views he cites ; and the making of the flexures over the region was due to the same cause ; that is, to the subsidence and not to heating from below. In the same paper, the general conclusion already referred to is drawn that a geosyncline of accumulation, like that of the Appalachians, is a necessary preliminary in all cases of mountain-making. In 1847, Bab- bage published the important principle (included in a paper read before the Geological Society of London in 1834) that in deepening accumulations of sediments, heat rises from below into the pile as its depth increases, as ex- plained on page 258, and that the subterranean heat causes changes of level through the expansion and contraction of the rocks. T. Mellard Reade, after a study of the expansion of heated rocks of dif- ferent kinds, adopting the views of Herschel and Babbage, attributes flexures, and other effects attending mountain-making, not merely to the heat from below indicated by the rising isogeothermals, but also to additional heat at intervals from a succession of intrusions of igneous rocks consequent on the conditions. He styles his theory "the origin of mountain ranges by sedi- mentary loading and cumulative recurrent expansion," recurrent because of the successive igneous intrusions. He found for the rate of expansion of average rock 2-75 lineal feet per mile for every rise of 100 F. The igneous intrusions are said to occur generally along the axis or axes of the range in process of construction. The principle that loading causes subsidence of the crust has been supplemented by C. King (1876) with its apparent complement that unloading by denudation causes elevation, he holding at the same time that these effects take place in a solid globe. The elevation of the Rocky Mountain area, during Tertiary time, is accordingly attributed by him to the removal, through denudation, of a vast amount of material from the vicinity of the Colorado canon, and from other parts of the mountains. With regard to the view of King, and especially this example under it, Le Conte has observed that the weight of the rock material elevated in the rise of the great mountain area to a height of 4000 to 11,000 feet was vastly larger than the amount lost by denuda- 382 DYNAMICAL GEOLOGY. tion, and adds that the denudation could not have produced any result until the elevation had made some progress. The theory supposes the isostatic condition of the globe ; and if this was the condition in Cretaceous time before the elevation began, the elevation never could have taken place without force from some real source. In accordance with the above, the evaporation of the flooded Great Salt Lake (called Lake Bonne ville), which, in the middle of the Quaternary era, had reached a depth of 1000 feet, has been suggested by G. K. Gilbert as the cause of the inequality of height in different parts of the terrace that marks its old coast-line. The change of level indicated is stated to be about 200 feet. The pressure of 1000 feet of water, or that removed by evaporation, is equivalent to 450 pounds to the square inch. The theory implies a molec- ular transfer (as the waters disappeared in the Middle Quaternary) from the outside region to that beneath the lake. The explanation is put forward by Gilbert with the statement that further investigation is required before the view can be regarded as estab- lished. The difficulty with the Gravitation Theory in its best form is that it does not supply the amount of pressure, and of contraction or expansion, which is required by the facts. This is true of Reade's theory, even with the recurrent work of igneous intrusions. In the case of the Appalachians the width of the geosyncline from S.E. to N.W. is less than 250 miles. The ratio of maximum depth to width is about 1 to 40, or that of a trough as wide as this printed page and one ninth of an inch deep. The depth of the strata, 40,000 feet, gives for the temperature at the bottom of the geosyncline (supposing the rate of downward increase to be 1 F. for each 50 feet of descent) 800 F. Conse- quently an expansion of 2-75 feet for 250 miles of width and for each 100 F. amounts to 5500 feet, or a little over a mile. Lesley makes the actual shortening over the breadth of the geosyncline in Pennsylvania, in con- sequence of the flexures, to be 44 miles, and Claypole 88 miles. The dis- crepancy is too large to be removed by questioning either estimate. Many of the single folds would use up several times the 5500 feet. So it is in other cases. In the Laramide Kange, of southern British America, a thickness of the rocks in the geosyncline of 34,000 feet, and the width of the trough about 150 miles, give for the tem- perature of the bottom about 700 F. ; and the expansion, under these conditions, would be only 2900 feet for the whole width. The displacement horizontally of one of the several faults, according to McConnell, is 7 miles, or nearly 13 times the maximum allowed for the range by the theory under consideration. In the Juras, Heim found the contraction by flexures to be 3 miles, or one fourth, for the distance between Lake Geneva and Saint Claude ; and in the eastern Jura to be 4 miles in a breadth of 7 miles. There is the further objection to the theory that in a trough, having the depth only a thirtieth or a fortieth of the breadth, the expansion would act nearly equally in all directions; so that while longitudinal ridges might prevail, transverse should be common instead of uncommon. But the ex- panding effects from the heat of successive igneous intrusions are to be added, according to the theory, ridges thus succeeding ridges. In the case of the Appalachians, there were no igneous intrusions along the chief part HYPOGEIC WORK. 383 of the axis of disturbance, and none in the Laramide Eange of British America, and the same is true in a large part of mountain-making. In the Wasatch the igneous effusions were a final effect, not an agent of change. Moreover, the pressure from any igneous intrusions, or their power of com- pression, is feeble. Plastic rock is little better for pressure than any pasty material ; when extruded it is hurried out of the way by the compression of any other agent, or escapes, if it can, by gravity. When it cannot escape, it bulges up the overlying beds and makes laccoliths (page 301), and this is almost its limit of mechanical work. The heat also is wholly inadequate for plicating and faulting rocks in mountain-making style, whether the liquid rock be granitic or of any other constitution ; the laws as to heating and cooling are the same for all kinds. 2. The Contraction Theory. 1. TJie source of lateral pressure. The source of the pressure accord- ing to the contraction theory is the contraction of the earth's crust as a con- sequence of cooling. The theory was suggested by Descartes in his Principia Philosophice in 1644, and by Newton in 1681, and was adopted in geology by James Hall, of Edinburgh, in 1812, and advocated by De La Beche in 1834. The contracting crust derives the lateral pressure from the cooling and solidification that is going on underneath it the crust being forced to adapt itself to an interior which is becoming smaller by the earth's gradual refrigeration. Mountain-making, according to the theory, is a con- sequence largely of the earth's shrinkage. The author's contributions to the subject, including also that of the Origin of Con- tinents and their Features, appeared first in the years 1846, 1847 and 1849, and were continued in 1856 and 1873. The development of the structure of the Appalachians through Virginia and Pennsylvania by the Professors Rogers afforded the first geological demonstration in favor of the contraction theory ; and the results they published, although leading the investigators at the time to a theory based on forced movements in the earth's liquid interior, underneath a thin crust, afforded the author illustrations of the views in his early papers. Since the earth has oceanic basins and continents of diverse dimensions and features, this lateral pressure would work with direct reference to conti- nental lines, and generally have its shoving and relatively resisting sides in epochs of orographic work. If the pressure acted thus unequally from the two opposite directions, it would make inequilateral mountain structures, or those having a front-and-rear character, like the Appalachian Range. Moreover, the movements would have their limits determined by, or re- lated to, the lengths of continents, or great continental regions, and, in this respect, they accord with the actual characters of mountain chains. The Laramide system, over 4000 miles in length, along the western continental border of North America, is an example ; and perhaps another 4000 miles 384 DYNAMICAL GEOLOGY. along a line farther west should be added for South America. The agent for such results must be the earth in its entirety. 2. Location of the lateral pressure. The surface layer of the globe in which the pressure acts has recently been shown to be thin. In the cooling and contraction of the crust, the lower part of the cooled portion, enveloping the uncooled nucleus that had not begun to lose its heat or contract, could not contract without breaking, and, therefore, the cooling would put it into a state of tension, which would result in the opening of fractures. For if a layer undergoing contraction is united to a non-contract- ing or less-contracting layer, the contraction would necessarily produce ten- sion and fractures. Thus the cooling crust must be made up of an inner portion in a state of tension and an outer in a state of lateral pressure, and the two portions are separated by a level of no strain. The outer is the effective part in orogeny. The lateral pressure within it is greatest at the surface, and diminishes downward. The thickness of the effective layer depends on the length of the time that has elapsed since the solidification of the earth at surface the time when the strain was initiated. It was esti- mated by Mellard Eeade as only two miles (1886). It has been mathemati- cally discussed first by C. Davison, and afterward by G. H. Darwin and M. P. Rudski, who sustain the contraction theory of mountain-making. Davison made the thickness (1887, '89) 2-17 miles, supposing the elapsed time to be 100,000,000 years; and Darwin (1887), two miles, for the same elapsed time, adding that "the depth is proportional to the time since consolidation." Davison, in a later "calculation (1894) based on the supposition that the coefficient of dilatation is not constant, as he before had assumed, but increases with the temperature," arrives at the more favorable conclusion that, after 100,000,000 years, "the depth of the surface of zero-strain would be 7-79 miles." He says further, that "if the material of the earth's interior be such that the conductivity and coefficient of dilatation are greater in it than in the surface rocks, or if initially the temperature increased with the depth, the above figure must be still further increased " ; and adds, in conclusion, "that, consequently, calculations as to the alleged insufficiency of the contraction theory to produce mountain-ranges are at present inadmissible." It is therefore safe to assume, in view of the dependence of mountain plications on lateral pressure, that the thick- ness was fully sufficient for the orographic results ; and even in late Archaean time great enough to make Archaean mountains of 8000 to 10,000 feet, such as the Adirondack and Black Mountains must have been before subjected to denudation. Darwin states at the close of his paper (which follows Davison's in the Philosophical Transactions), after deducing that contraction vanishes at a depth of 2 or 3 miles : " Thus, in 10,000,000 years, 228,000 square miles of rock will be crumpled on the top of subjacent rocks. The numerical data with which we have to deal are all of them subject to wide limits of uncertainty, but the result just found, although rather small in amount, is Such as to appear of the same order of magnitude as the crumpling observed geologically. HYPOGEIC WORK. 385 The stretching and probable fracture of the strata at some miles below the surface will have allowed the injection of the lower rocks amongst the upper ones, and the phenomena, which we should expect to find according to Mr. Davison's theory, are eminently in accordance with observation. It therefore appears to me that his view has a strong claim to acceptance." Further, Mr. Darwin cited, in 1892, the recent calculations of Rudski of Odessa, which showed that if the initial temperature of the sphere be not uniform through the mass, that is, if, as in the case of the earth, the initial temperature increased from the surface to the center, the level of no strain lies deeper than he had made it. As to the actual depth thus indicated he made no statement. (Phil. Mag., Sept., 1892.) 3. Tlie process of mountain-making according to the Contraction Theory. The making of the preparatory geosyncline, with its included series of strata, was slow in its progress. As it included, in the case of the Appalachians, all of Paleozoic time to the close of the Carboniferous, the rate of subsidence the depth being 40,000 feet was, if the time was 40,000,000 years, about 1 foot in 1000 years ; if 10,000,000 years, 1 foot in 250 years. The rate, on either supposition as to the elapsed time, was so slow that the subsidence may have been a result of the loading of the area with the sediments. Yet it can- not be asserted that lateral pressure in the crust was not concerned ; for if it was the prime cause of movements at the crisis, it could hardly have been dormant through the long preceding ages when the trough was in progress. The subsidence went forward, so far as can be discovered, without much dis- placement of the beds within them, beyond such as were due to unequal compression by gravitation, drying, and some solidification. The pile of beds had great breadth as compared with its depth, and varied much in thick- ness, owing to irregularities in the Archaean floor beneath, and to varying rates in the progress of the subsidence. Limestones indicate much slower movement downward than coarse sediments of like thickness ; and inter- calated beds of coal prove that long periods of slight emergence were among the alternations. When the mountain-making crisis was at hand, the temperature at the bottom of the deposits was already high from the rise of the geothermals with the increase of thickness. With a thickness of 40,000 feet, and the rate of increase of temperature downward 1 F. in 50 feet, it would be 800 F. But the rate was probably as rapid as 1 F. in 40 feet or less, making the temperature at bottom 1000 F. or higher. At either temperature the trough would have been greatly weakened below, as first explained by Herschel. In a letter addressed to Lyell, dated February, 1836, and in another to Murchi- son, dated November, 1836, which are published in the Appendix to Bab- bage's Ninth Bridgewater Treatise (1837), he presents, besides the view that heat will rise from below into an accumulating series of strata, as had been done by Babbage, the suggestion that " the thicker the deposit, the hotter will its lower portions tend to grow, and if thick enough they may grow red- hot, or even melt. In the latter case, their supports, being also melted or softened, may wholly or partially yield under the new circumstances of pres- D ANA'S MANUAL 25 DYNAMICAL GEOLOGY. sure, to which they were originally not adjusted; and the phenomena of earthquakes, volcanic explosions, etc., may arrive." These results are favored by the fact that the deposits were not half consolidated, and, there- fore, little able to resist the pressure. In the consequent collapse from the continued pressure, the included strata would be necessarily shoved up out of place, flexed in anticlines and synclines, and traversed by great oblique fractures, as Daubree's experiments illustrate, which would become the courses of displacements, all on a scale of magnitude comporting with the thickness of the accumulated formations. The flexures were not flexures of the earth's crust, but of the supercrust, or the beds in the geosyncline. The work was slow in progress ; for the great flexures in such mountain-making are produced without obliterating or seri- ously obscuring the stratification. In the great forced movement, if the pressure on the two sides of the trough was unequal, as was commonly the fact, the beds were shoved from the side of strongest pressure, or thrust, toward the opposite. Consequently the flexures became crowded and steepest on the former side, and the over- thrust flexures and upthrust blocks were thrust toward the other side. Hence the resulting mountain range and its flexures are inequilateral. In the case of the Appalachians, the thrust was strongest on the side toward the ocean. Further : on the side of least pressure, the mountain range often declines into elevated plateaus, with feebly undulating or horizontal stratification, as exemplified, on the landward side of the Appalachians, in the Cumberland plateau and its continuation northward; in the Uinta Mountains and the high plateaus of Utah on the landward side, and to the south, of the Wasatch. In the narrow troughs of deposition of eastern North America, the flexures often fail to indicate inequilateral pressure. After a mountain-birth there has commonly succeeded a time of relaxed lateral pressure ; and then occurred adjustments, largely by gravitation, in the moved masses or faulted blocks making chiefly downthrow displace- ments, besides producing new fractures and faults. Such displacements have taken place especially in the region of mountain plateaus, where the pressure was least. Illustrations of the steps in the contraction process of mountain-making have been above derived mostly from the Appalachian Range. They may be found almost equally apposite in most of the mountains of the world, as the examples already given prove. The Taconic Range, on the borders between New England, and New York and Canada, has the same general characteristics as the Appalachian, with the addition of the universal meta- morphism of the beds of sandstone, shale, and limestone. Its preparatory geosyncline was on a parallel line with the northern part of the Appala- chian; and the two were deepening and taking in deposits together until the close of the Lower Silurian, when the Taconic mountain-making crisis came. The rocks of the range are, therefore, only those of the Cambrian and Lower Silurian. It is probable that this mountain belt extends through HYPOGEIC WORK. 387 Virginia southwestward, along a series of Taconic geosynclines that ended in the making of a series of Taconic ranges, on a line east of the Appala- chian Range. See further, pages 531, 532. 4. Geanticlines corresponding to the geosynclines. It is not always easy to identify the one or more geanticlines that the sinking of a geosyncline may have produced. In the case of the Taconic and Appalachian ranges little doubt exists. When the Taconic Range was completed, already a low geanti- cline had risen above the continental sea, making two large islands between southern Ohio and Alabama, one over the region of Cincinnati and part of Kentucky, and the other in the same line over Tennessee. The region, often called that of the Cincinnati uplift, was first identified as a Middle Silurian emergence by J. S. Newberry and J. M. Safford. Moreover, an eastern geanticline also showed itself ; for the whole Atlantic border from New York southwestward through Virginia and beyond became emerged at the same time, and continued so, with probably increasing height through the Upper Silurian, Devonian, and Carboniferous eras, when the making of the Appalachian Range took place ; and also after this, through the Triassic and Jurassic periods until the Middle Cretaceous ; for through all this time no beds with marine fossils were formed over this great area. The contraction theory of mountain-making, as is seen, appeals to an all- pervading force that must have been at work from the time the earth first had a solid exterior. Already in later Archaean time it had made Archaean mountain ranges ; and it is manifest, from succeeding events, that through- out all time one system of evolution was in progress. Moreover, the theory has the virtue of explaining the facts, which is not true of the gravitation theory. No other adequate explanation has been proposed. If the calcula- tions of physicists do not give a sufficient depth for the results to the " level of no strain/' then the calculations may be believed to be in error until some other adequate cause of the great faults and flexures has been brought forward. 5. Relations of mountain ranges to denudation. Carving, gouging, and leveling through denudation go on very rapidly in elevated regions of even a moderate amount of rain, and have gone on through long ages since the rocks were made, so that the original forms of the anticlines and synclines of mountain ranges have disappeared, generally leaving ridges where synclines once existed. Yet the geologist may still have little difficulty in tracing out the plica- tions, even if the region over which they extend is now a level plain. The investigator looks for evidence of folds in change of dip. If, on his way westward over a region, he finds eastward dips changed to westward, he has passed the axis of an anticline ; and if, going farther, he finds westward dips changed to eastward, he sees proof that he has reached the axis of a syn- cline. Complexities are added by the great faults, making difficulties which can hardly be surmounted without the aid of fossils. From the facts presented in the above review of the structure of moun- 388 DYNAMICAL GEOLOGY. tain ranges, the reasons for the directions of drainage courses over such regions are easily understood. The prevailing courses are longitudinal as regards the range ; not because synclinal troughs are longitudinal, for these, in the case of bold flexures, are not ordinarily the courses of river valleys ; but for the more general reason that the flexures and faults in the range are longitudinal. The greater valleys are made along anticlines, because of the profound longitudinal fracturing of their summits, in consequence of the tension produced by the upward bending of the strata. This leaves the intervening synclinal belt as the course of the mountain ridges. Besides, the synclinal strata come under extreme pressure during the flexing process, and may have derived by this means greater durability. If the rocks of the range are crystalline schists and limestone, the limestone yields easily to denudation, and would determine in general the course of the drainage channel. But among uncrystalline rocks, limestone is harder than shale and some sandstone. It has been stated that in a region of upturned rocks, as that of the Appalachian Range, the flexures are made in series along a few parallel lines, and sometimes in a succession of groups ; and consequently that those of different lines often overlap at their extremities. Hence, along these intervening or overlapping portions the strata are irregularly warped and fractured, and thus weakened. Here, consequently, erosion should be easy, and transverse or oblique courses of drainage would result. Great mountain ranges and systems have been shown to have one or more curves in their courses. The Appalachian Range, for example, changes from its south-by-west course in New York to west-southwest in Pennsyl- vania, and then leaves this state with a south-southwest course, which to the southward veers again to west-southwest. Here is another cause for trans- verse lines of drainage ; for such a range usually diminishes in height over its more nearly meridional or more latitudinal part. In the Appalachians the lower part is along the latter ; and here, as Lesley's map of Pennsyl- vania shows (page 730), the range is crossed by the Susquehanna. Finally, along a region of a number of close-pressed folds, having great longitudinal fractures with displacements, a drainage valley may take great width. If the plications or monoclines over an extended area have small dip, then the broad synclines and the depression between monoclines or lines of displacement may become the courses of streams. Epeirogenic movements that give a height of many thousands of feet to large continental areas add these thousands to the elevation of the moun- tain ranges along the region; and hence, besides causing flows of water down the gentle slopes, they produce a vast increase of precipitation and denuda- tion about the summits, and make the streams great rivers. Over the in- terior of continents such movements may cause undulations or warpings of the surface, which occasionally reverse the flow of rivers, or unite inde- pendent river systems into one, or make depressions that become the basins of lakes. HYPOGEIC WORK. 389 6. Ranges, Systems, Chains, Cordilleras in North America. From the explanations given it is apparent that a mountain range includes all the mountain ridges made over the area and border of a single geanticline. The Appalachian is an example 900 miles long ; it comprises many ridges, but these are made by denudation. Ranges are the individuals or units in mountain structures. A mountain system includes all ranges in a region made in different, more or less independent, geosynclines at the same epoch. Besides the birth of the Appalachian Range at the close of the Carbonic era, there was also the birth of an Acadian Eange, from Newfoundland through Nova Scotia, and probably to Ehode Island. Here are two simultaneously made ranges on the Atlantic border, and they may be regarded as parts of an Appalachian mountain system. Again, in western Arkansas, the upturned Paleozoic rocks constitute the Ouachita Mountain range, which, as L. S. Griswold has suggested, pertains to the Appalachian Mountain system, the axis of uplift conforming to the southern portion of the latter in Tennessee and Missis- sippi. As another example, the Wasatch Mountains constitute one of the Laramide ranges. But the mountains to the north of Montana, in British America, described on pages 359-60, were evidently made over another trough in the same line, and correspond to another Laramide range. So there are others, and as many as there were independent or partially independent Laramide troughs along this line in the Kocky Mountains; and all the mountain ranges originating from these troughs make up the Laramide Mountain system of North America, over 4000 miles long. A mountain chain is a combination of mountain systems, or mountain belts of different epochs. On the Atlantic side, there is, along the Appalachian belt, a combination consisting of the Appalachian system of post-Carbonifer- ous age, the Tacoriic system of Middle Silurian age, and an Archaean system ; and the Palisade mountain system, of Jurassic age, may be added. Together they constitute the Appalachian Chain. In the Rocky Mountains, the main Rocky Mountain Chain of British America, which, as has been stated, is continued southward along the Wasatch Range, includes an Archaean system and the Laramide or po'st- Cretaceous system. The chain is not continued in sight, south of the Wasatch; but the line is an important geological boundary, it being the western limit of the Cretaceous formation, and the eastern of the Great Basin. The Front Range of Colorado, as it is called, is the course of another Archaean system and also of other Laramide uplifts, and, therefore, of another summit chain, which may be called the Colorado Chain. Again, nearer the coast, the mountain belt which includes the Sierra Nevada of California, the Cascade Range of Oregon and Washington, the long Coast Range of British Columbia, as it is called by G-. M. Dawson, together with the range to the south, 1000 to nearly 5000 feet high, along the California peninsula, are parts of a Sierra chain, combining ranges or systems of ranges, of Archaean and later time. In like manner there is a 390 DYNAMICAL GEOLOGY. Coast chain commencing to the south in the Coast ranges of California, and continuing along the islands of British Columbia, and on the sea border beyond to Mount St. Elias. Finally, the combination of two or more chains makes a Cordillera, as the term is used in South America for the Andes. Accordingly, the Coast and Sierra chains together with the chains of the Eocky Mountain summit constitute the Cordillera of the Rocky Mountains. In South America the term cordillera is used not only for the Andes as a whole but often also for one of its long ridges or ranges or chains. The combined mountain systems of the whole Pacific border of North America were first called a Cordillera by J. D. Whitney. By the above definitions, range, system, chain, are no longer interchange- able terms, dependent for their use on extent or complexity of mountain regions, but have fixed significations. Study of a mountain range. Since an individual mountain range has great magni- tude, and commonly great complexity through its long series of involved flexures and faults, and through the excavating work of running waters, investigation requires a long and searching study of the structure as a whole, that is, as an individual. The geological examination of a single ridge of a range may afford conclusions as to the fact of upturnings, flexures and faults and may obtain evidence as to the force concerned, and perhaps settle the question of the foliation, or bedding, of the schists of the ridge, if any are present. But it can afford no general conclusions as to the range ; and a petrological investigation would accomplish still less. A single section across the range would afford facts, but no general results ; for the flexures may vary every few miles, new faults appear and other rocks come out to view. The student should make his sections not merely in one, or a dozen transverse lines, but in as many lines as possible in all directions, studying positions of strata, and noting the changes they undergo from ridge to ridge until the connection of each ridge with every other in the general system of warping has been ascertained. Further, this study should be carried on until the true limits of the mountain individual as far as possible are ascertained. And if the range is more or less metamorphic, the belt of maximum metamorphic change should be studied out, and the fringe of diminishing change, on one or both sides. A ridge of upturned rocks, whether Archaean or of later date, is almost invariably evidence of the existence, in the region, of a mountain range 100 to 1000 miles long, or more ; and this should be assumed to be a fact until the contrary is proved. With the completion of the investigation there will be little further reason for ques- tionings about the fact of pressure and movements as a source of dynamical effects ; and if the beds are metamorphic, none as to the source of the heat that produced the meta- morphism. But it remains for petrology to complete the work by investigating the special characteristics of the metamorphic changes, their relations to the positions of the beds, the minerals due to the original metamorphism and the results of later changes, besides other points in the history, for light upon which geology is dependent on its kindred science. Further, a mountain range being a very large individual, a length of a thousand miles and breadth of more than a hundred being common, three such individuals cannot exist on a single area of 50 miles square. When, therefore, indications of three or more periods of upturned rocks are announced, as indicated, by unconformabilities in any limited region of upturned crystalline or uncrystalline rocks, Archaean, or others, it is quite certain that the unconformabilities are in part only unconformities through faults, or overlaps, or erosion, which have little epochal significance. HYPOGEIC WORK. 391 In addition, it should be remembered that the unconformabilities between the upturned rocks of a mountain and those underlying are usually confined to the mountain region. A score or so of miles to one side, the rocks may often be found resting beneath the same strata, perhaps horizontally, with perfect conformability between them. The unconform- abilities are on this account none the less important as time -boundaries in geological history. When, in consecutive epochs of mountain- making, the upturned strata of the later epoch have been thrust up against those of the earlier, by force acting in the two cases from the same direction, the two sets of strata will have more or less nearly the same strike. But their unconformability may possibly still be proved (1) by difference in dip ; (2) by difference in kinds of rocks, when the rocks are studied over a long belt in the line of strike ; and (3) by fossils, if the beds are fossiliferous. But when the strata are metamor- phic, and fossils are therefore absent, the difficulties are great. Examples occur in western Connecticut and eastern New York, where the metainorphic Taconic rocks come into con- tact with Archaean. The first and second of the above criteria may still be available, though with great uncertainty ; the second may be used especially when the two sets of strata differ in grade of crystallization or metamorphism, or in the presence of some dis- tinctive mineral masses, as of metamorphic beds of iron ore. The belt should, further, be traced along the range of outcrops in order to find, if possible, a region where there is a bend in the strike ; for at such a bend the two sets of strata probably would not be found to bend alike ; and to make the investigation complete, all possible strikes and dips should be measured and plotted on a large map of the region. Special care is needed in order that unconformity produced by a fault is not mistaken for true unconformability or that in the bedding. 3. GENERAL RESULTS OF OROGRAPHIC WORK. 1. Effect of orographic work on the earth's circumference. Faults and plications are a measure of the shortening of the earth's circumference that has taken place in an orographic crisis. During the ages of preparation, the amount of shortening in the making of the geosyncline has been small ; for the slowly accumulating strain reduces widths only by the difference between the shallow arc and its chord. But at the collapse, as already shown, the amount has been a score or more of miles : 74 for the Alps (Heim) ; 44 for the Appalachians in Pennsylvania; 25 for the Laramide Range in British America (McConnell). The line of the Appalachian Range is transverse to a zone of the globe having a N.W.-S.E. direction ; and the Taconic Range and the Acadian of Nova Scotia and New Brunswick widen this zone northward. The short- ening of the earth's circumference for all these ranges was not east-and-west, but in the direction of this zone. In this zone the Archaean nucleus is to the northwest; but to the southeast lies the Atlantic, in its long range between North and South America. In western America, where the mountains made range northwestward instead of northeastward, the shortening was in the direction of a zone N.E.-S.W. in course. It was the same zone of the globe that includes the Alps. The whole amount of shortening on the Atlantic border was probably not over 50 miles along the course of the zone; and on the Pacific border for the Laramide and other systems later than the Archaean, not over 75 miles. 392 DYNAMICAL GEOLOGY. 2. TJie mountain chains and volcanoes of the continents mostly confined to their borders. The facts on these points are briefly mentioned on page 32 and beyond. The situation of the chains on the continental borders, so well exhibited in North America, and the position of the greater mountain- mass of this continent, greater by 25 times, on the borders of the larger ocean, have manifestly a cause that is in some way connected with the mutual relations of the border region and the oceanic basin adjoining. The author has explained these features (1847, 1873) on the view (1) that the lateral pressure at work was lateral thrust chiefly from the oceanic direction against the continental borders (the landward side of the border region being the side of least pressure or greatest resistance); and (2) that since the oceanic area was depressed below the level of the continental, the thrust was in a small degree obliquely upward. If the crust in which the strain exists has only five miles of depth, there is still stronger reason in favor of this expla- nation, and for accepting it also as accounting for the making of the greater mountain-mass on the side of the widest ocean; for width of ocean, not depth, is the important element. The view explains equally the abundance of border volcanoes. 3. Great mountain uplifts in the later part of geological time and also great igneous ejections. The fact that the highest and broadest of moun- tains and the chief part of the mass of the continents were lifted above the ocean mostly after the Cretaceous period is one of the most marvelous in geological history. After the crust had become stiffened by the thickening, plication, and solidification, and partly the crystallization, of the strata of the supercrust, the chief movement in mountain regions, caused by the ever-continuing lateral pressure, was an upward one, and then mountain chains received through epeirogenic movements their great heights. Under the same cir- cumstances, moreover, igneous ejections and volcanoes reached their maxi- mum at the close of the Cretaceous and during the Tertiary. In correspondence with the great continental geanticlines of the Tertiary and later time, there should have been oceanic geosynclines, for the material constituting the rising mass could have had no other source than the crustal mass beneath the oceans. On this point there is the great fact of the sub- sidence over the central Pacific, described on page 349, of which the coral islands are a monumental record. Its area was hardly less than 6000 miles in length, and the breadth, reckoning only from the Hawaiian to the Friendly Islands, over 2500 miles. Such a subsidence fully meets the demands of the Pacific-border geanticline of North America. It suggests, also, that the other great mountain-masses, uplifted during the Tertiary and Quaternary, among them the lofty Andes and the still loftier Himalayas, derived a supply of material by a like method from beneath the oceans. Under this compensating relation, the two great movements become one epeirogenic evenly, and, therefore, the combined result of one comprehensive cause. 4. North America a type-continent. Among the continents, North HYPOGEIC WORK. 393 America best exhibits typical continental growth, because it stands by itself between the two oceans, free from other lands on the east, south, and west. In this it is greatly in contrast with Europe and Asia. In all its structure it shows that its orographic courses were outlined at its incep- tion, and that its features were gradually developed from age to age, in accordance with the foreshadowed system. The Archaean protaxes have almost the lengths of the adjacent continental borders, and the systems of ranges of later elevation, on the Atlantic and Pacific sides, have parallel courses and like extent. They are not irregularly distributed groups or knots of mountains, but elevated lines in the continental structure, orderly placed according to principles and forces that were already at work in Archaean time. Hock-making went forward under like comprehensive methods with the mountain-making. When Archaean time closed, North America comprised a great Interior Continental or Mediterranean Sea, partially separated by the protaxes from the continental-border seas on the Atlantic and Pacific ; and, besides, there were, in some parts of the borders, parallel troughs or basins between Archaean confines. Through the following ages, these seas were doing their various work in rock-making, bringing first to a finish, and emergence with orographic aid, the eastern half of the continent ; and then giving a like degree of progress and emergence to the western half ; and, finally, under a comprehensive agency, carrying the whole area, from east to west, to completion. 5. The earth an individual in development. The system of feature-lines, displayed in the islands of the Pacific, is virtually that of a hemisphere, for nearly half of the equator lies between the ocean's eastern and western limits. It may be rightly taken, therefore, as the system of the globe. All north-and-south lines are subordinate lines in this system. There is no network of pentagonal lines of dislocation (De Beaumont), or of tetrahedral lines (William L. Green, 1857-1887), or of dodecahedral lines, as urged by E. Owen, of Indiana, in his later paper on the earth's features (1888); for the existence of continental regions and oceanic basins implies local differences in the nature of the material over the sphere, when surface cooling began, that made such lines of symmetry impossible. Instead, the actual physiog- nomy includes long parallel ranges of lines, often bending in great curves, with transverse lines nearly at right angles, and a reference in all to the positions and forms of the continental and oceanic areas. The island chains of the Pacific, 1000 to 5000 miles long, are separated by underwater valleys, reaching in some cases to depths of 28,000 feet, or over 40,000 below the highest island summits. The system of feature-lines of the oceans is exhibited also by the continents, but with irregularities incident to the forms, positions, and consequent resistances of the nucleal land-masses. System through regular progress is abundantly proved, but the special causes determining the details of the system are not yet all understood. The following are some of the points awaiting explanation : 394 DYNAMICAL GEOLOGY. (1) The gathering of the dry land, the continents, the earth's individ- ualities, and arenas of progress, mostly toward the north pole, and of the waters as largely toward the south pole, the great cause of continental differ- ences in the system of progress. (2) The attitude of the continents on the globe, each mass having the broader extremity to the north and narrowing southward a fact which Bacon, in his Novum Organum, set forth as a problem for solution. (3) The zigzag arrangement of the northern and southern continents, South America having its center 40 east of that of North America, and Australia, as far east of that of Asia. (4) The separation of the northern and southern continents by a volcanic belt that girts the sphere. (5) The two systems of courses in the grand feature-lines of the conti- nents and oceans nearly at right angles with one another, the more equatorial and most prevalent varying between N. 60 W. and N. 70 W., but curving to N. 30 W., and the transverse system with correlate variations. (6) The existence of a greater mean depth in the western half of the Atlantic and Pacific Oceans than in the eastern half, notwithstanding the fact that the continental border adjoining the west Pacific is a region of high mountains with many volcanoes in the continental islands, and that the border adjoining the west Atlantic has the lower mountains of North America and no volcanoes. These characteristics of the earth necessarily date from the beginning of solidification ; and the first the existence of a larger part of the continental masses in the northern hemisphere and of the oceanic area in the southern may have involved the others. For, if the alleged excess of density in the crust beneath the oceans is owing to the prevalence of basaltic rocks, the crust of the oceanic basin would have remained in fusion after that of the continental had generally cooled through an era long enough for a loss of 300 to 500 Fahrenheit, a fact that would have determined differential conditions and consequences at the first cooling of the earth's crust. The zigzag arrangement of the continents has been attributed to torsion ; and the belt of volcanoes that girts the world has been pointed out as the belt of maximum torsion, and the courses of the earth's feature-lines as consequences in part of the pressure or tension attending torsion ; and thus an explanation that reaches deeply into the subject of origins has already been presented. W. L. Green (1875 and 1877), in The Vestiges of a Molten Globe, sug- gested the idea that the mass of the continental plateaus, occupying the northern hemisphere, caused, during the incipient stage of the first formed crust, a retardation in the rotation of this part of the floating crust, and thereby "a shearing strain . . . between the crusts of the northern and southern hemispheres," and hence a yielding to this strain along the earth's great volcanic belt ; remarking that thus " South America became separated from its northern half continent, and pushed toward Africa," while Asia, in HYPOGEIC WORK. 395 the northern hemisphere, was crowded westward on to Europe and Africa, leaving Australia to the eastward. Daubree, in 1880, explained the same characteristics of the sphere by reference to torsion in the crust during its contraction, and referred to the facts as according with his experiments described in his Experimental Geology. W. Prinz published a paper in the Annuaire de V Observatoire Royal de Bruxelles for 1891, in which he points out the resemblances between the great continental torsion courses of the earth, and the lines that have been observed on some of the planets. The western outline of North and South America shows well the obliquity of one of the greater torsion courses and movements. On the following diagram, Fig. 347, it is the outline to the left. Parallel with this, as Prinz explains, and about 90 to the eastward, 347. Oblique courses in the earth's grander outlines. Prinz. there is another, that of the western coast of Africa, continued northwest- ward to Greenland ; and 90 farther eastward, there is a third, following the course of the western side of Asia, from the Urals and Spitzbergen to western Sumatra and Australia. A fourth is also supposed by him to be indicated in the middle of the Pacific, nearly 90 more to the eastward, where the great central chain of islands in the ocean bends northward, and crosses the equa- tor in the Marshall Islands. Prinz shows further from published maps that similar oblique lines have been observed on Mars (Fig. 348), and less dis- tinctly on Venus and Jupiter. Finally, he states that M. Duner, by means of the spectroscope, has been able to determine that in the sun the 75th 396 DYNAMICAL GEOLOGY. degree of latitude makes a complete revolution in 38-6 days, while the equator revolves in 25'5 days. The fact of torsion appears thus to be sustained for the other planets as well as for the earth. 348. Oblique feature-lines on Mars. Prinz. Prinz introduces, in closing, the diagram in Fig. 349 to illustrate the general scheme of torsional movements. He implies that such movement may have begun in the incipient stages of surface consolida- tion, whenever the continen- tal and oceanic areas began to be differentiated, and that in the process a cleavage structure was produced that determined the system of fractures in the earth's sur- face, and thereby the system in the earth's feature -lines. But he adds that the solu- tion of all the questions that arise demands the profound- est knowledge of celestial mechanics, as well as much experiment, and a complete discussion of the records in the earth's structure. Historical geology adds greatly to the interest of geomorphic work, by presenting in detail the connection of mountain-making movements with the preparatory stratigraphic events, and also by bringing out to view the bear- ings of these great topographical changes on the physical conditions of the earth, and their influence on biological distribution and progress. PAKT IV. HISTORICAL GEOLOGY. SUBDIVISIONS IN GEOLOGICAL HISTORY AND METHODS OF CORRELATION. NATURE OF SUBDIVISIONS IN THE HISTORY. IN the study of geology, there is often an expectation to find strongly drawn lines between the eras and periods, or the corresponding subdivisions of the rocks ; but geological history is like human history in this respect. Time is one in its course, and all progress one in plan. Some grand strokes there may be, as in human history there is a begin- ning in man's creation, and a new starting-point in the advent of Christ. But all attempts to divide the course of progress in man's historical devel- opment into periods with bold confines are fruitless. We may trace out the culminant phases of different periods in that progress, and call each culmi- nation the center of a separate period. But the germ of the period was long working onward in preceding time, before it finally came to its full develop- ment and stood forth as the characteristic of a new era of progress. It is all one progress, while successive phases stand forth in that progress. In geological history, the earliest events were simply physical. While the inorganic history was still going on (although finished in its more funda- mental ideas) , there was, finally, the introduction of life, a new and great step of progress. That life, beginning with the lower grades of species, was expanded and elevated, through the appearance of new types, until the introduction of Man. In this organic history, there are successive steps of progress, or a series of culminations. As the tribes, in geological order, pass before the mind, the reality of one age after another becomes strongly appar- ent. The era of Mammals, the era of Reptiles, and the era of Coal-plants oome out to view, like mountains in the prospect, although, if the mind should attempt to define precisely where the slopes of the mountain end, as they pass into the plain around, it might be greatly embarrassed. We note here the following important principles: First. The reality of an era in history is marked by the development of some new idea in the system of progress. 397 398 HISTORICAL GEOLOGY. Second. The beginning of the characteristics of an era is to be looked for in the midst of a preceding era ; and the marks of the future coming out to view are prophetic of that future. Third. The end of an era may come, either after the full culmination of the idea or phase, or earlier, at the commencing prominence of a new and grander phase in the history. It may be as ill-defined as the beginning, although its prominent idea may stand out boldly to view. Thus the era of Coal-plants was preceded by the occurrence of related plants far back in the Devonian. The era of Mammals was foreshadowed by the appearance of mammals long before, in the course of the Reptilian era. And the era of Reptiles was prophesied in types that lived in the earlier Carboniferous era. Such is system in all history. Nature has no sympathy with the art which runs up walls to divide off her open fields. Fourth. Mere length of time, without culminating or characterizing events beyond that of rock-making, is not a criterion of value in the subdividing of geological history. CORRELATION OF THE RECORDS. The chronological order is that demanded, as in any history. The first object is, accordingly, to ascertain which are equivalent strata, or those of the same geological horizon, and where in the chronological succession each stratum belongs. As even the shorter divisions of geological time have in general been of very long duration, the equivalent or correlate strata of distant regions can- not be known to be precisely synchronous in origin. A long time, measured by thousands of years, may in fact have intervened between the commence- ment of beds that are most alike in all those points by which age and equiv- alency are determined. Huxley, in view of the impossibility of determining true synchronism, proposed to designate by the term homotaxial (from the Greek 6//,os, same, and rais, order) those strata, in regions more or less widely separated, that have apparently the same relative position in the geological series. Difficulties. The following are some of the difficulties encountered in attempts to ascertain the true chronological succession : 1. The stratified rocks of the globe include an indefinite number of lime- stones, sandstones, shales, and conglomerates ; and they occur horizontal and displaced ; conformable and unconformable ; part in America and part in Europe, Asia, and Australia ; here and there coming to view, but over wide areas buried beneath soil and forests. Moreover, even the same bed often changes its character from a sandstone to a shale, or from a shale to a limestone or a conglomerate, or again to a sandstone, within a few miles or scores of miles, and sometimes within a few rods; or, if it retains a uniform composition, it changes its color so as not to be recognized by the mere appearance. In the United States, many a sand- SUBDIVISIONS IN GEOLOGICAL HISTORY. 399 stone in New York and Pennsylvania is of cotemporaneous origin with a limestone in the Ohio and Mississippi valleys. Some rocks in eastern New York are not found in the western part of that state, and some in the central and western part not in the eastern. 2. In all periods, sand-beds, mud-beds, clay-beds, pebble-beds, and lime- stone-beds have been simultaneously in progress over different parts of the globe ; and, if a period is known in geology as solely a period of limestone, it is because science has not yet discovered where the beds of sand, mud, or pebbles were being deposited while the limestone was making over its regions. The idea of a period of sandstone-making, or of limestone-making, is therefore an absurdity ; for sand deposits are local ; a short distance off, there may have been, in all times, as now, mud deposits. Still, it is true that, over continental seas, the prevailing depositions have sometimes been of limestone material, and sometimes of mud or sand ; yet this has been true for certain great regions in the seas of a continent, rather than for all its seas at once. 3. Again, a stratum of one era may rest upon any stratum in the whole of the series below it, the Coal-measures on either the Archaean, Silurian, or Devonian strata ; and the Jurassic, Cretaceous, or Tertiary on any one of the earlier rocks, the intermediate being wanting. The Quaternary in America in some places rests on Archaean rocks, in others on Silurian or Devonian, in others on Cretaceous or Tertiary. 4. In addition, denudation and uplifts have thrown confusion among the beds, by disjoining, disarranging, and making complex what once was simple. Amidst all these sources of difficulty, how is the true order ascertained ? Means of correlation. The following are the means employed : 1. Order of superposition. When strata are little disturbed, vertical sections give the true order in those sections ; and so also may outcrops of inclined strata over the surface of a country. In using this method by superposition, several precautions are necessary. Precaution 1. Proof should be obtained that the strata have not been folded upon one another, so as to make an upper layer a lower one (see page 104), a condition to be suspected in regions where the rocks are much tilted. Precaution 2. It should be seen that the strata 350. under examination are continuous. A fault in the rocks may deceive ; for it makes layers seemingly continuous which are not so. Faults are common in regions of upturned rocks and may occur when the dip is slight. In some cases, beds forming the upper part of a bluff (as ab, Fig. 350) have settled down bodily (c) to the bottom, so as to seem to be continuous with the older ones of the bottom (as c with d). In other cases, caverns in rocks have been filled through openings from above, and the same kind of mistake made. 400 HISTORICAL GEOLOGY. When the continuity can be established, the evidence may sometimes lead to unexpected results. For example, it may be found that a coal-bed, followed for some miles to one side or the other, is continuous with a shale, and both are actually one layer ; that a sandstone is one with a limestone a few miles off ; that an earthy limestone full of fossils is identical with a layer of white crystalline marble in a neighboring district ; or that a fossi- liferous shale of one region is the same stratum with the mica schist of another. Precaution 3. Note whether the strata overlie one another conformably or not, that is, conformably as regards bedding. Precaution 4. Remember that, where one bed overlies another conform- ably, it does not follow necessarily that these beds belong to consecutive periods, as has been above explained. The criterion mentioned, order of superposition, unless connected with others, gives no aid in comparing the rocks of distant or disconnected regions. For this purpose, other means must be employed. 2. Color, texture, and mineral composition. These characteristics may sometimes be used to advantage, but only within limited districts and always with distrust. There were at one time in geology an "old red sandstone" and a " new red sandstone " ; and, whenever a red sandstone was found, it was referred at once to one or the other. But it is now well understood that color is of little consequence, even within a small geographical range. Mineral composition has more value than color, especially when it is not one of the common kinds. But it is usually to be disregarded. One inference from the mineral constitution of a stratum is safe ; that is, that a stratum is more recent than the rock from which its material was derived. Hence, an imbedded fragment of some known rock may afford important evidence with regard to the age of the containing stratum. But the presence of such a fragment does not prove that a long time intervened ; the imbed- ding may have happened in the same period in which the earlier beds of the formation were made. The beds made and consolidated in modern time are often torn up by the waters and put into new beds in some other place. Coral limestones of recent seas are often conglomerates of the recent coral limestone. Limestone breccia is sometimes formed out of the blocks at the foot of a bluff of limestone from which the blocks had fallen. 3. Although mineral composition is ordinarily unsafe, it has value when two or more conformable strata of constant mineral characters accompany one another. Such evidences may prove identity for hundreds of miles. The association of schist, limestone, and quartzyte from central Vermont to Connecticut and beyond, with only small gradational changes in each of the rocks, serves to identify the Taconic series through its wide distribution. 4. Fossils. The criterion for determining the chronological order of strata dependent on kinds of fossils takes direct hold upon time, and, there- fore, is the best ; and, moreover, it serves for the correlation of rocks all over the world. The life of the globe has changed with the progress of time. Each SUBDIVISIONS IN GEOLOGICAL HISTORY. 401 epoch has had its peculiar species, or peculiar groups of species. Moreover, the succession of life has followed a grand law of progress, involving under a single system a closer and closer approximation in the species, as time moved on, to those which now exist. It follows, therefore, that identity of species of fossils proves approximate identity of age. Equivalency is sometimes shown in an identity of species ; more often in a parallel series of nearly related species ; often by an identity or close rela- tion in the genera or families ; often also in some prominent peculiarity of the various species under a family or class. Through a comparison of fossils, it was discovered that the Chalk forma- tion exists on the Atlantic border of the United States, although the region contains no chalk; that the Coal formation of North America and that of Newcastle, England, belong in all probability to the same geological age ; and so on. The progress in life has not consisted in change of species alone. The species of a genus often present, in successive periods, some new feature ; or the higher groups under an order or class some modification, or some new range of genera, so that, even when the species differ, the habit or general characters of the species, or the range of genera or families represented, may serve to determine the era to which a rock belongs, or at least to check off the eras to which it does not belong. Thus Spirifer, a genus of mollusks, which has a narrow form in the Silurian, has often a very broad form in the course of the Devonian and the Carboniferous ages. Ganoid fishes, which have vertebrated tails through long ages, have their tails not vertebrated in after time. Trilobites become wholly extinct at a certain epoch in their his- tory. These are examples of a principle availed of in multitudes of cases presenting minor differences. Much aid is derived also from the canon brought forward by Agassiz in the first volume of his Poissons Fossiles (1833, pages 208-270), and con- sidered at length in one of the chapters in his Natural History of the United States (i. 112, 1857) : that, under the various tribes, the geological succession of species often corresponds in some of the more general characteristics with the succession of phases in the development of living representatives of those tribes. In other words, geological succession and modern embryologi- cal succession have near parallelisms. Agassiz says, in his work on Fossil Fishes (vol. i, page 169) : " J'ai deja eu plus d'une fois occasion de faire remarquer la grande analogic qu 'il y a entre certain es formes embryoniques, qui sont passageres dans le developpement des individus, et les caracteres constans d'une foule de genres de differentes families, qui n'ont que peu de representans dans la creation actuelle, ou qui sont completement eteints." In his work on the Natural History of the United States, on page 112 of the chapter on "the Parallelism between the geological succession of animals and the embryonic growth of their living representa- tives," Agassiz states the principle as follows : "The phases of development of all living animals correspond to the order of succession of their extinct representatives in past geological time." DANA'S MANUAL 26 402 HISTORICAL GEOLOGY. In illustration : the vertebrated tails of the ancient Ganoids is one ex- ample, since this feature is a characteristic of the young of living Ganoids, and also of some other living fishes. The cartilaginous skeleton of the ancient Ganoids is another embryonic feature. The stem of the ancient Crinoids occurs in the young of the related Comatula. The Mastodon, as regards its teeth, says Agassiz, and in some other points, is embryonic in its relations to the Elephant. Paleontologists of skill derive a degree of prophetic power through the aid of the canon. The shells of Ammonites have been shown by A. Hyatt to afford an excellent illustration of the principle. Noting that the coiled shell contained within it all the forms it had passed through from the embryo stage to the adult, he proved by his studies of the shells of different genera that the embryological succession corresponded in a general way with the geological succession, and hence that the position in the geological scale of any new species was approximately determinable from its form. It is obvious that through the knowledge thus obtained stratigraphical doubts may often be removed. Moreover, where direct paleontological observation has ascertained in particular cases the steps of progress in the development of organs, as, for example, those of the teeth in Mammals, the facts become a basis for further use in the same direction. But decisions on such grounds have to be made with great reserve ; since there were often, throughout paleontological his- tory, retrograde steps in the various tribes of species, and, not unfrequently, in some organs when the general progress was upward. Man stands at the head of Mammals, and yet, as regards his teeth, he is below the Monkeys, and related to the earliest Tertiary Mammals. By the methods which have been above described, great progress has been made in arranging the rocks of the different continents in a chronologi- cal series. North America has large blanks in the series which in Europe are filled. In this and other ways the countries of the world are contribu- ting to a general system of life history. Precautions in the use of fossils for correlation. Precaution is required for the following reasons : 1. The difference in species attending difference of conditions in climatCj soilj etc. In the same regions, during any era, the species of the land differ from those of the waters ; those of fresh water from those of salt ; those of the surface or shallow waters from those of deeper ; those of warm waters from those of cold, whether at the surface or in the deep ocean where oceanic currents make differences of temperature ; those of warm or dry lands from those of cold or wet ; those of clear open seas from those of muddy waters or near muddy seashores ; those of rocky bottoms from those of muddy ; etc. Hence, an ancient rock made in a clear sea, as a limestone, will necessarily contain very different fossils from a rock that was made of mud, although they were formed at the very same time, in the same waters, and within a hundred miles of one another. Even a hundred yards may be all that separates widely different groups of species. Again, a rock made SUBDIVISIONS IN GEOLOGICAL HISTORY. 403 in fresh waters will differ in its fossils still more widely from that made synchronously in salt waters ; a rock made in shallow waters from one made at great depths ; a rock made in the tropics from one made in the temperate zone or the arctic, provided the zones at the time of the making differed as they do now in climate. Hence, a very considerable difference in the fossils of rocks is consistent with their being contemporaneous in origin. ?. As a consequence of the above facts, or the dependence of life on food, temperature, and other physical conditions, migrations in species or faunas will take place whenever there is a marked change in the waters; it may be for a few miles or many. Barrande, first in 1852, pointed to examples of such migrations in his " Colonies," as he styled them ; cases of advanced occurrence locally of a fauna that afterwards disappeared, but later became the prevailing fauna of a region, which he explained by migra- tion, implying, as Geikie observes, that "particular species appeared with the conditions favorable to their spread and disappeared when these ceased." The case is the same when the fauna of a bed, which has apparently become extinct, has recurrences in an overlying stratum whenever there is a recur- rence of the kind of deposit. In and out the species go with the changing conditions. Hence, as H. S. Williams has said, " the actual order of faunas met with in a vertical section is not necessarily expressive of biological sequence, but only of the sequence of the occupants of that particular area." Such recurrences of species are likely to be met with in all regions where fine shales, coarse shales, argillaceous sandstones, quartzose sandstones, with or without limestones of varying purity, are in alternation. 3. The difference in the time at which species or groups have begun to exist in different regions. The several continents may not have been exactly parallel, in all the steps of progress in the life of the globe. Certain families may have commenced a little earlier in one than in another ; or again, one conti- nental sea or region, over a continent, may have received some of its species by migration from another, long after their first appearance. Here is a source of doubt : what may be due, on one side, to special continental idiosyn- crasies in condition or history, and, on the other, to migrational distribu- tion, is always to be carefully considered. An example of the doubts and difficulties which may be thus occasioned is afforded by the Cretaceous and Tertiary formations of North America and Europe. Fossil plants of the Rocky Mountain Cretaceous have been pronounced Tertiary by European paleontologists who judged from comparisons with European Tertiary species ; and yet the animal fossils of associated beds made it certain that they were Cretaceous : and the query has thence arisen whether the European plants may not be the successors of emigrants of Cretaceous American species which, through this means, became characteristic in Europe of a post-Cre- taceous period, or, whether the differences are not indigenous to the sepa- rate continents. 4. The difference in the time at which species or groups of species of differ- ent regions have become extinct. In one region, changes may have caused 404 HISTORICAL GEOLOGY. speeies or genera (or higher groups) to disappear, while, in another sub- jected to the same conditions or causes of catastrophe, the same species, or at least the same genera (or higher groups), may have continued on through another period. Genera or Families may have become extinct sooner on one continent, or part of a continent, than on another ; or in one ocean, or part of an ocean, than in another. Again, catastrophes may affect the shallow borders of an ocean, and not reach to a depth of a hundred fathoms. 5. The absence of fossils from a formation, or their extreme fewness, even when the formation is thousands of feet thick, is no evidence as to the paucity of life in the era. The absences may be owing to local conditions ; or to the trituration of fossils to the finest of particles which infiltrating waters could wash out ; or to the waters of the region having been fresh. A case in the later Paleozoic is that of the Devonian Catskill Red sand- stone 3000 to 4000 feet thick, whose fossils are very few brackish-water or fresh-water species. When formed, the seas of the world contained as large and varied a fauna as in the period of the great Devonian limestones or that of the Subcarboniferous Crinoidal limestones. Such blanks need explana- tion ; for the equivalent fossiliferous can hardly be absent from the whole of a continental area. 6. The inferior value of plants to animals as tests of geological age of equivalency is generally admitted. It appears to be true also that marine fossils are entitled to greater weight than terrestrial or fresh-water species excepting the fossil Vertebrate. But the evidence from Vertebrates is always surest when fortified by that of Invertebrates. The difficulties are not often sources of final doubt when the conclusions are based on the general range of animal types characterizing an era. Should a Trilobite be hereafter discovered in any Cretaceous rocks of the world, it would lead no one to suspect those rocks to be Paleozoic, because the asso- ciated species would be sufficient to settle the question of age. Among metamorphic rocks, the outcrops of the rock should be followed into the region of feeble metamorphism where traces of fossils may possibly be found. By studying the relations of the associated rocks as to bedding, and proving conform ability and continuity, the discovery of a few fossils in one stratum of the series at a single locality may settle the question of age approximately for a whole formation hundreds of miles in length. SUBDIVISIONS OF GEOLOGICAL TIME. General basis of subdivisions. In view of the principles explained in the preceding pages it follows that 1. The grander divisions of geological time should be based, in a com- prehensive way, on organic progress, independently of events connected with rock-making and disturbances of the crust. Examples of such divisions are those of the four primary divisions, the Archaean, Paleozoic, Mesozoic, and Cenozoic. SUBDIVISIONS IN GEOLOGICAL HISTORY. 405 2. Subordinate divisions should recognize the same criterion, but should depend for their limits, as far as practicable, on physical breaks or events registered in the rock-series, and on abrupt transitions in kinds or groups of fossils. Since the latter are dependent on physical changes, they are a con- venient criterion when characterizing large areas. 3. When subordinate divisions of the higher grades have been estab- lished on any continent, or part of a continent, these divisions should be recognized and adopted as nearly as possible in the study of other regions, and their limits determined if possible by means of the fossils ; for only in this way can the history of different regions be brought together into one sys- tem. For example : the Permian period, recognized and defined in European geological history, should have its place in American geological history, however intimately the beds and their fossils in America may blend with those of the Carboniferous period. So also the Devonian of Europe should be recognized and have like limits, as nearly as may be, in the Devonian of America. A degree of fixedness in the higher subdivisions and their names is necessary to prevent confusion in the literature of the science and the frustration of its great purpose, the production of a comprehensive earth-history. 4. Inferior subordinate divisions so far depend on local conditions, that those of different continents, and even of distant parts of the same continent, generally require, in the first study of a region, special designations to avoid assumptions of closer relationships or equivalency than can be made out. The different continents, and often also unlike regions of the same continent, have had their special histories. The periods and epochs of America and Europe are not in general the same in limits, and much less so in rocks. The Devonian subdivisions are different on the two continents ; and it is far from certain, also, that the commencement assigned to the Devonian in North America is synchronous with that in Europe. In the Carboniferous, Rep- tilian, and Mammalian eras the American epochs differ from the European. There is much diversity between the subdivisions in New York and those of the Mississippi valley, and still greater between these and the subdivisions of the Pacific slope and border. Even in Pennsylvania the formations fail of many of the subdivisions that are prominent in New York. Hence in the study of a new region it is necessary at the outset to make arbitrary subdivisions of its formations, such as may seem most convenient and natural, and give them local names. These names have at first only a note-book value. When the relations of the beds to those recognized in other regions have been ascertained through fossils, the facts begin to take their places in the general geological history of the country ; and should the correlation be complete, the local names may give way to those generally accepted elsewhere. It is of the highest importance to remember that state boundaries are only political limits, and not, ordinarily, at least in America, true geographi- cal or geological limits ; and if the subdivisions of one state which have 406 HISTORICAL GEOLOGY. already received local names extend into the adjoining, the introduction of new names in the latter is a wrong to the science. 5. In all cases, the characteristics of the species and the beds should be carefully scrutinized, lest abruptness due to local migrations (as those caused by slight changes of depth or currents and kinds of sea-bottom) should be mistaken for abruptness of real importance. Physical and Organic Breaks. Prominent among the events influencing the rock-structure and life of a continent is that of mountain-making. The Appalachian Mountains stand as a grand time-boundary between the Paleozoic aeon and the Mesozoic ; and cotemporaneous orographic movements make a like limit in European geology. Moreover, it was attended by the most remarkable of organic breaks. The Taconic mountains mark the close of the Lower Silurian, an epoch of abrupt change in North America; and parallel disturbances occurred in Britain and Europe. The Laramide or post-Cretaceous mountain system along the Kocky Mountains is another such boundary for America, separating Mesozoic and Cenozoic time, though not as complete in the attendant organic break as in the physical. But it so happens that no corresponding event occurred at this time in Europe, the orographic movements most nearly synchronous taking place after the com- mencement of Cenozoic time. Nevertheless, th organic break at the close of the Cretaceous period is even greater for Europe than for America. Such a fact seems to show that there was some other catastrophic event concerned ; but its nature is yet to be studied out. Part of the breaks referred to above were limited in their effects to the hemisphere including America, Europe, northern and middle Asia, and northern Africa. The opposite hemisphere, that of India, Australia, and South Africa, has been more or less independent, although the two were alike in many characteristics ; and owing to this, the boundary closing Paleozoic time, so strongly marked in the geological history of Europe and America, cannot be satisfactorily denned in the latter. The coal period is of later date than that of Europe and America, it occurring in the Permian, and the Permian period blends with the Triassic. Such orographic time-boundaries are registered not only in the rocks that are upturned, but also in unconformabilities between them and the succeed- ing rocks. It is important to note, however, as already stated, that the unconformability exists only in upturned regions. A short distance away, the succeeding beds will be found lying conformably over the same kinds that are upturned in the mountains ; moreover, the organic break there may be less pronounced, and in more distant regions it may fail altogether. The unconformability is, however, none the less important as a time-boundary, for orographic upturnings have been events of great geographical extent after long ages of preparation. The Subdivisions. The several grades of subdivisions of geological time are named (1) ^Eons, (2) Eras, (3) Periods, (4) Epochs; and the corresponding terms applied to the formations are Series, Systems, Groups, SUBDIVISIONS IN GEOLOGICAL HISTORY. 407 Stages. For intermediate divisions sub is prefixed to the name of the division next above. Still lower subdivisions are termed zones, and receive special designations from a characteristic fossil. Subdivisions of zones, corresponding to the vertical distribution of species, have been recently called hemerce, from the Greek for day. In place of any of the above terms, the word time may be used in its usual sense whenever it is thought convenient. It is substituted beyond for the word ceon. I. ARCHAEAN TIME. The beginning of Archaean time was without life ; but before it closed conditions had been reached that admitted of the exist- ence of protophytic and protozoic life. II. PALEOZOIC TIME. Characterized by the more ancient kinds of life, closing with the period of the great Coal formations of Europe and America, so named from TroAaio's, ancient, and wrj, life. III. MESOZOIC TIME. The life of mediaeval types or kinds ; closes with the period of the Chalk or Cretaceous formation, so named from /xros, middle, and ^OM/. IV. CENOZOIC TIME. The life of more modern types, continuing to the present time, so named from KCUVOS, recent, and a>rj. The term Paleozoic was proposed by Sedgwick in 1838, and preferred and adopted by Murchison the same year in place of his own name Protozoic, it "involving no theory." For the terms Mesozoic and Cenozoic, and the upper limit of the Paleozoic, the science is indebted to Professor John Phillips, of Oxford, England. Cenozoic is sometimes written Cainozoic or Kainozoic. But in English, derivatives from the Greek diphthong at become ce or e, as in Ethiopia, Eolian, Egypt, Etna, ether, hematite ; and K becomes c, as in center, circle, calyx, camel, and multitudes of other words. Lyell's names for divisions of the Tertiary, namely, Eocene, Miocene, Pliocene are examples of both cases, the ce in each being K, joint, and a-oris, foot). But the typical Worms and the Arthropods are alike in consisting of a series of segments, each normally having its nervous ganglion ; and in this fundamental feature, which is more important than their differences, both sections are far removed from Mollusks and Brachiopods, which are non- articulates, the body and its appendages having no joints. On this account the old division of Articulates still has importance. The relations of Insects are even closer, structurally and embryologically, to Worms, than to Crustaceans, notwithstanding their jointed limbs. This relation of Insects to Worms is shown by the resemblance of the larves to Worms ; while Crustaceans, by the same evidence, are proved to be most nearly related to the precursors of Worms. The grander divisions of Invertebrates are as follows : ARTICULATES. 1. ARTHROPODS. a. The terrestrial or Tracheate species : 1. Insects ; 2. Myriapods; 3. Arachnids. b. The aquatic or Branchiate species : 4. Limuloids ; 5. Crustaceans. , WORMS. NON-ARTICULATES. 3. MOLLUSKS; 4. MOLLUSCOIDS (including Brachiopods an* Bryozoans). The non-segmented Worms might here make another subdivision. {5. ECHINODERMS. 6. CCELENTERATES, including Hydrozoans (or Medusae and Hydroids), and Actinozoans (or Polyps). 7. SPOXGIOZOANS, or the animals of the Sponges. 8. PROTOZOANS, Amceboids, Rhizopods, Radiolarians, Monads, and other Flagellates, etc. 1. Arthropods. The TRACHEATES have spiracles (breathing-holes), a vascular system for inside air- circulation, and one pair of antennae, or none ; they include Insects, Myriapods, Arachnids. The BRANCHIATES have gills for the aeration of the circulating fluid, or perform this function through the general surfaces of the body or its foliaceous appendages. The spe- cies are Crustaceans, Limuloids, and Pycnogonids. 1. Insects. Having the body in three parts, that is, a distinct head, thorax, and abdomen ; and only three pairs of legs : as Hymenopters (Ants, Bees, Wasps) ; Lepidopters (Butterflies, Moths) ; Coleopters (Beetles) ; Dipters (Flies) ; Neuropters (Dragon-flies, May-flies) ; Orthopters (Grasshoppers, Locusts, Cockroaches) ; Hemipters (Cicada, Squash-bug, Aphis); Thysanura (Podura, Lepisma). 2. Myriapods. Having a worm-like form, regularly articulate body, and numerous pairs of legs; part have the body flattened, and one pair of legs to a segment or somite, the Chilopoda, which include the Scolopendra and other Centipeds ; and others have the body nearly cylindrical, and two pairs of legs to a segment, the Diploopoda, which include the lulids and other Millepeds. 420 HISTORICAL GEOLOGY. 3. Arachnids. Having the body in two parts, cephalothorax and abdomen (but in the lowest, Mites, only one, the abdomen and thorax not separate segments) : as Spiders, Scorpions, Mites, Ticks. 4. Limuloids. Limuloids are a nearly extinct tribe of species, related more nearly to the Arachnids than to Crustaceans. The only species in American waters is the Limulus polyphemus, or Horse-shoe, common on the coast of southern New England and to the southward. Limuloids differ from Crustaceans in not passing through the Nauplius stage in embryo- logical development ; in having no antennae corresponding to the first pair in Crustaceans ; and in having the two antennae of the second pair chelate ; that is, terminating in pincers, and used for conveying food to the mouth, a degenerate service for sense-organs. A Paleozoic group, under the tribe of Limuloids, includes the Eurypterids aquatic species having the long, jointed body of a Caligus among Crustaceans, but occasionally several feet in length. For figures, see pages 556, 623. They have two antennae, like the Limulus, or none, and, moreover, the basal joints of part or all of the legs are the ani- mal's jaws. Although aquatic species, they are related to the Scorpions, a division of Spiders. See further, page 513. 5. Crustaceans. The class of Crustaceans is divided into : (1) Decapods (so-named from the Greek for ten-footed}, as the Crabs, Lobsters, Shrimps, usually having 5 pairs of feet. (2) Tetradecapods (named from the Greek for fourteen-footed), as the Sow-bugs and Sand-fleas. (3) Entomostracans, irregular in number of feet, and usually without a regular series of abdominal appendages. 376-385. ARTICULATES. (1) Worms: 376, Arenicola marina, or Lob-worm (x). (2) Crustaceans: 377, Crab, species of Cancer; 378, an Isopod, species of Porcellio; 379, an Amphipod, species of Orchestia; 380, an Isopod, species of Scrolls (x ) ; 381, 382, Sapphirina Iris; 381, female; 382, male (x 6); 383, Trilobite, Calymene Blumenbachii ; 384, Cythere Americana, of the Cypris family (x!2); 385, Anatifa, of the Cirriped tribe. In an early stage of development, many young Crustaceans have a 6-footed free- swimming form, called a Nauplius, 2 of the feet being functionally antennas and 4 of them legs, the third pair afterward becoming jaws. All Entomostraca pass through this Nauplius stage, and also a few of the higher kinds. Among the Decapods, Crabs are called Brachyurans, from the Greek for short- tailed, the abdomen being small and folded up under the body ; the Lobsters and Shrimps, BRIEF REVIEW OF THE SYSTEM OF LIFE. 421 Macrurans, from the Greek for long-tailed, the abdomen being rarely shorter than the rest of the body. Among the Tetradecapods, Figs. 378, 380 represent species of the tribe of Isopods (a word meaning equal-footed), and Fig. 379 of that of Amphipods (feet of 2 kinds). Fig. 378 is the Sow-bug, common under stones and dead logs in moist places. Fig. 379 is the Sand-flea, abundant among the seaweed thrown up on a coast. Under Entomostracans, the Cyclops group (Copepods) includes very small species having a shrimp-like, or Caridoid, form, as in Fig. 381. Sometimes the male and female differ much in form : 382 is male, and 381 female of Sapphirina Iris ; ab is the cephalotho- rax, and bd the abdomen. In the Cypris group, the animal is contained in a bivalve shell, as in Fig. 384, and they are hence called Ostracoids. In the Phyllopod group, the form is either Caridoid, approaching Cyclops, or like Daphnia or Cypris; but the abdominal appendages or legs are usually foliaceous and excessively numerous : the name is from the Greek for leaf-like feet. The Ostracoid Phyl- lopods are multiplicate species (that is, excessive in number of body segments or limbs) of the tribe of Ostracoids, and the Caridoid kinds often resemble multiplicate species of Copepods. In the Cirriped or Barnacle group, the animal has usually a hard, calcareous shell, and is permanently attached to some support, as in the Anatifa (Fig. 385) and Barnacle. The animal opens a valve at the top of the shell, and throws out its several pairs of jointed feet looking a little like a curl, and thus takes its food, whence the name, from the Latin cirrus, a curl, and pes, foot. The Anatifa has a fleshy stem, while the ordinary Barnacle is fixed firmly by the shell to its support. Barnacles are common on the rocks of the seacoast between high and low tide. The young Cirriped or Barnacle is a free-swim- ming Ostracoid, much like Fig. 384 in form, but, on passing to the adult stage, it drops its bivalve shell, and commences the sedentary life of the species, and the hard, permanent, calcareous shell of the animal is then formed. As with other Crustaceans the animal periodically casts its skin with progress in size, but not the hard calcareous shell about the body. The shell of ordinary Crustaceans is not calcareous, but chitinous, and more or less flexible ; the Cirripeds are an exception as regards this outer shell, but not in the integument over the legs and body within this shell. The composition of the chitinous covering of a lobster is given on page 73. Trilobites are Paleozoic Crustaceans related to the Isopods. They have the general form of an Isopod, the higher division of the Tetradecapods, and were placed near this group, with a query, by the author in 1852. But they are Phyllopod-like or multiplicate species, with the exception of a few of embryonic relations. Like the Isopods, and unlike spe- cies of Apus, and most other Entomostracans, they undergo no metamorphosis. Trilobites are represented in Figs. 383, 386, and 387-391. In the Trilobite, the shell of the head-portion (ab, Fig. 383) is called the buckler; the tail (or properly, abdominal) shield, when there is one (Fig. 383, d), the pygidium. The buckler (a&) is divided by a longitudinal depression into the cheeks or lateral areas, and the glabella or middle area (Figs. 383, 386) . The cheeks are usually divided by a suture extending from Dalmaniteg HaU8manni . the front margin by the inner side of the eye to either the posterior or the lateral margin of the shell. In Fig. 383 (Calymene BlumenbacMi) , this suture terminates near the posterior outer angle. The glabella may have a plane sur- face, or be more or less deeply transversely furrowed (Fig. 383), and usually has only three pairs of furrows. The suture running from the anterior side of the eye forward or out- ward, and from the posterior side of the eye outward (s in Fig. 386), is the facial suture; a prominent piece on the under surface of the head, covering the mouth, is called the 422 HISTORICAL GEOLOGY. hypostome. The eyes may be very large, as in Dalmanites (Fig. 386), Phacops, and Asa- phus (Fig. 689), or small, as in Homalonotus ; or not at all projecting, as in Trinucleus (Fig. 692) ; and may also differ in position in different genera. 387 387-391. TRIARTHRUS BECKII. Figs. 387, 388, specimens with antennae and portions of cephalic and thoracic ap- pendages (x 2) ; 389, portion of antennae (xlO); 390, posterior half, with remains of feet (x2); 391 a, one of ttie jointed appendages (x 6) ; 391, one of the feet. Matthew. Specimens of Trilobites are almost always without appendages of any kind. Evi- dence of pairs of slender limbs extending the whole length of the body were first observed in a specimen of Asaphus platycephalus, by Billings, in 1870 ; and later, in 1883, in another American species, A. megistos, by Mickleborough. New proof was announced by Walcott, in 1876, 1877, and 1881, from slicings of some hundreds of specimens of a species of each of the genera Calymene and Ceraurus; who reached the conclusion that there were four pairs of slender appendages to the head-portion, and a series along the whole under surface to the extremity of the pygidium or abdomen. He also obtained evidence that the thoracic legs had at bases a branch (epipodite), and that they carried also an appendage in the form of slender filaments, some of which were spiral, which he described as probably branchial. Mr. Walcott also gives figures of what he regards as the fossil ova of the Trilobites. These results have been in the main confirmed and made more definite from specimens of Triarthrus Beckii, found by W. S. Valiant, and described, in 1893, by W. D. Matthew, some of which are represented in Figs. 387-391, from Matthew's paper. In addition to the existence of legs, the specimens figured show that Trilobites had slender antennae of the first pair (Figs. 387, 388), consisting of short joints (Fig. 389); and that the slender, bifid, jointed feet were, in part at least, natatory organs, probably, by plumose setse (as is indicated in Fig. 388 and others). The presence of a second pair of antennae is probable, but none is indicated. The specimens were from a thin layer in the Utica shale near Rome, Oneida County, New York. Later investigations of specimens from the same locality, by C. E. Beecher (1893, 1894) have ascertained that the abdominal appendages are branchial, as in modern Isopods ; he has also made out the precise form and other characters of the thoracic limbs, show- ing that each consisted of a seven-jointed leg, and a long natatory appendage. (See page 512 for figures.) The following table exhibits the homologies, as regards segments and their appendages, of different types of Crustaceans. indicates the absence of a segment, and the Koman numerals above, the normal number of the segments in the cephalothorax and abdomen. BRIEF REVIEW OF THE SYSTEM OF LIFE. 423 CEPHALOTHORAX. ABDOMEN. I , 1. DECAPODS Pedunc. (Crab). eyes. 2. TETRADECA- PODS. II III 2 pairs of antennae. 2 pairs of antennae. iv v vi vn vm ix x xixn xmxry inmivvvi 6 pairs of mouth 5 pairs of feet, organs. 6 pairs of abdominal appendages. 4 pairs of 7 pairs of feet, mouth organs. 6 pairs of abdominal appendages. 3. CYCLOPS. 2 pairs of antennae. 3 pairs one 4 pairs of 000 of pair natatory mouth feet. feet, organs. usually no appendages except to last segment. 2. Worms (Vermes). Worm-like in form, consisting of many segments not always distinct, without jointed legs, though often furnished with tubercles, lamellae, or bristles. Examples : the Earth- worm, marine Annelids, Leeches. Among the Annelids or higher Worms, the Arenicola, or Sand-worm family, includes species that burrow in the sands of seashores ; Fig. 376 represents the A. marina, or Lob-worm, which is common on European and American shores, and grows to the size of the finger. One species of Eunice has a length of 4 feet. They are supposed to be related to the Scolithus of the Cambrian (Potsdam Sandstone). Species of Tubicolce, of the Serpula tribe, live in a calcareous or membranous tube, and have a delicate branchial flower, often of great beauty, near the heads. The tubes often penetrate corals, and the branchial flower comes out as a rival of the coral polyps around it. The Rotifers are generally made a subdivision of the Worms. They are minute species, having 3 to 6 body segments ; 1 or 2 simple eyes ; a pair of jaws ; disks, situated anteriorly, which are edged with movable cilia in place of limbs. Many have, in appearance, the cephalothorax and jointed abdomen of an Entomostracan, and in this and other ways show a relation to Crustaceans. They are supposed by Lankester to have comprised the precursor species of Annelids, Crustaceans, Limuloids, and other Arthropods ; and others compare the forms of some with the embryos of Mollusks, Molluscoids, and Holothurians, relations that would make the group the Embryonoid division of the higher Inverte- brates. For figures of Rotifers and references see article ROTIFERS in the Encycl. Brit. The Helminths, or Intestinal Worms, need no especial remarks in this place, as they have no geological importance. 3. Mollusks. Mollusks consist essentially of a soft, fleshy bag containing the stomach and viscera, without joints or jointed appendages. They were named Mollusks from the Latin mollis, soft. They have on either side a thin fold of the skin of the back, called the mantle or pallium (from the Latin for cloak), which serves to inclose a cavity between it and the body, where are the gills (branchiae) or aerating organs. The mantle varies from very large to nearly obsolete ; and in some (the Pulmonates or land-snails) it is a covering for an internal lung-like organ of respiration. The ventral surface anteriorly has sometimes a firm, fleshy projection which serves as a foot for locomotion, as in the Clam, or for their attachment by horny fibers, as in the Mussel. Again, it is sometimes spread out flat, making a large, flat foot or ventral surface for locomotion, as in the Gastropods ; or it has the anterior part divided into a pair of wing-like paddles, as in the Pteropods ; or into 4 424 HISTORICAL GEOLOGY. or 6 pairs of arms furnished with tentacles, suction-disks, or horny claws, as in the Ceph- alopods. The subdivisions are as follows : 1. Cephalopods. Free-swimming; having 4 or 5 or more pairs of arms arranged about the mouth (Fig. 392), so named from Ke$a\-i}, head, and irovs, foot. Some, like the Nautilus, have an external chambered shell, and others (Squids) only an internal bone or pen. Rhyncholites, sometimes found as fossils, are the hawkbill-like jaws of the species of Ammonites. The subdivisions are: the Tetrabranchs, or 4-gilled species (Fig. 401), including the Nautili and Ammonites, and the Dibranchs, or 2-gilled species, which never have an external chambered shell, and include the large Devil-fishes and the Argo- naut, or Octopods ; the Cuttle- fishes and Squids, or Decapods (Fig. 392). In the latter group, one pair of arms is very long, and there is an internal horny 392. The Calamary or Squid, Loligo vulgaris (length of body, 6 to 12 inches) ; t the duct by which the ink is thrown out; p the " pen." or calcareous bone (shell) some- times called the pen (Fig. 392, p) situated in the back. One spe- cies of the Newfoundland seas has the body 15 feet long and the long arms about 35 feet. The Sepia, from its ink-bag, affords the brown paint called sepia; and its "pen" is the spongy cuttle-fish bone used to supply lime in bird-cages. 2. Pteropods. Free-swimming species, having for the purpose of locomotion (Fig. 400), a pair of paddle-like plates near the head ; shell, when present, often slender, conical, thin, and glassy, but also of other shapes, and rarely spiral (Limacina). Named from irrep6f, wing, and TTOVS. 3. Scaphopods. The foot adapted for burrowing. Shell tubular, conical, or oblong, slender, as in Dentalium. Named from o-wa^os, digging, and irovs. 4. Gastropods (Cephalophora). Head prominent and furnished with eyes and usually tentacles (Fig. 399) ; the mouth with a rasp-like tongue ; the foot, for locomotion, a broad, flat, ventral surface, whence the name of the group (from yacrr^p, the venter) ; shell, a dorsal secretion, usually spiral, but in Chiton, a jointed symmetrical shield ; in some, conical ; sometimes wanting. Includes the Snails (Fig. 399) among land species, and the spiral shells of fresh and salt water, often called Univalves ; also species without shells, some of which (Nudibranchs) have the gills in flower-like groupings on the back. The mantle varies much in extent, reaching (at the will of the animal) as far up the outside of a shell as the surface is highly polished. Besides the eyes of the head, several species of Naked Mollusks of the genus Onchidium have eyes over the back ; and these eyes, unlike those of other Invertebrates, are like the eyes of Vertebrates in structure, a layer of rods and cones forming the outer layer of the retina, and the general arrangement of the parts being Vertebrate-like (Semper, Animal Life, 1881, page 371). 5. Lamellibranchs (Figs. 396-398). Include the Clam, Oyster, and other " bivalves." They have no eye in the head portion, and no projecting head (whence called Acephals}, and no teeth or denticles in the mouth. The foot in many is a tough, keel-shaped, or flattened muscular projection ; but sometimes it is small and spins horny fibers (byssus) for attachment to rocks, and sometimes (as in Oysters, etc.) it is wanting. They have a bivalve shell, the valves situated either side of the body, and articulated together above between the umbones. The valves show, inside, the impressions of one (at 2, Fig. 398) or BKIEF KEVIEW OF THE SYSTEM OF LIFE. 425 two (1, 2, Figs. 396, 397), rarely more, adductor muscles, and also an impression of the mantle or pallium, which is concentric with the lower and hinder margin of the shell in integripallial species, and has a sinus posteriorly in sinupallial species. The mantle is large, concealing the body, with the two sides either free at the lower edge, or not con- 393-401. MOLLUSKS, Figs. 393-401. (1) Brachiopods : 393, Terebratula impressa, of the Ob'lyte; 394, Lingula on its stem. (2) Jiryozoans : 395 (x 8), 395 a, genus Eschara. (3) Lamellibranchs : 396, 397, 398, the Oyster. (4) Gastropods: 399, Helix. (5) Pteropods : 400, genus Cleodora. (6) Cephalopoda: 401, Nautilus (xj). nected (as in the Oyster, etc.), or else grown together into a sac (Venus, Mya}-, and in the latter case usually having the sac terminate behind in two tubes, as in My a, Solen, one incurrent, for receiving water, to the gills, and food, and the other excurrent. Imper- fect eyes or eye-spots exist in the mantle of some species. Gills are usually lamellar organs (whence the name, Lamellibranchs) situated between the mantle and the body. In a few boring species, the shell includes, or is followed by, a long, calcareous tube, which may be 1 to 2 feet long in Teredo, the timber-borer. 4. Molluscoids. 1. Brachiopods. Brachiopods (Figs. 393, 394, and 402-430) have a bivalve shell, and in this respect are like the Lamellibranchs or ordinary bivalves. But the shell, instead of covering the right and left sides, covers the dorsal and ventral sides. More- over, it is symmetrical inform, and equal, either side of a vertical line ab, Fig. 407. The valves, moreover, are almost always unequal ; the larger is the ventral, and the other the dorsal. There is often an aperture at the beak (near 6, Fig. 393), that in the young state and often through the adult gives exit to the pedicel, by means of which the animal is fixed to some support. Species having the two valves hinged together are called Articu- late Brachiopods, and those that are hingeless are the Inarticulate. Some of the genera of the former group are Orthis, Orthisina, Spirifer, Ehynchonella, Strophomena, Penta- merus, Terebratula; and some of those of the latter are Lingula, Lingulella, Obolus, Obolella, Discina, Crania. Brachiopods have a pallium, but no independent branchial leaflets ; and a pair of coiled fringed arms, which in some cases may be extruded, whence the name Brachio- pod, meaning arm-like foot. For the support of these arms, there are often bony processes (Figs. 402, 406, and 409). These calcified arm-supports, when present, are 2 thin lamellae, attached to the interior of the dorsal valve ; they are short and curved in the 426 HISTORICAL GEOLOGY. Rhynchonellse (Fig. 411); are extended toward the front of the shell, and bent back and united, forming a loop, in Terebratula, Magellania, etc. (Figs. 403, 404, and 402); or are extended forward and coiled in variously shaped spiral coils, as in Spirifer, Atrypa, etc. (Figs. 405, 408). In many extinct genera (Orthis, Strophomena, etc.) there are no calcified arm-supports. These arms are covered with vibrating cilia, which serve to keep up a current of water over or through the branchial cavity of the animal. A few of the species are represented in Figs. 402-430 : 402-421. BBACHIOPODS. Fig. 402, Magellania flavescens ; 403, loop of Terebratula vitrea ; 404, id. Terebratulina caput- serpentis; 405, Spirifer striatus; 406, same, interior of dorsal valve; 407, Athyris concentrica; 408, 409, Atrypa reticularis, the latter dorsal valve; 410, Rhynchonella psittacea, showing the spiral arras of the animal; 411, id. dorsal valve; 412, id. ventral; 413, Strophomena planumbona; 414, id. dorsal valve; 415, id. ventral; 416, Plectambonites transversalis; 417, id. dorsal valve; 418, id. ventral; 419, Orthis stria- tula; 420, id. dorsal valve; 421, id. ventral. BRIEF REVIEW OF THE SYSTEM OF LIFE. 422-430. 427 Fig. 422, Productus aculeatus, dorsal view ; 4'J3, Producing seiuireticulatus, veutral view ; 4:i3 a, section of Pro- ductus, showing Ihe curvature of the valves; 424, Cbonetes latus, opposite views; 425, Calceola sanda- lina (a Coral with lid, resembling a bivalved Brachiopod) ; 426, Crania antiqua; 427, Discina (Discinisca) lamellosa, side view; 428, id. showing foramen; 429 a, b, Sipbonotreta unguiculata, opposite views; 430 a, b, Obolus Appollinis. Brachiopods are among the oldest of fossils. The animals have been shown by Morse to have close relations to the Annelids, though not multiplicate like them, but when adult without distinct segments. 2. Bryozoans (Polyzoans). Bryozoans, or Moss-animals (so named with reference to the moss-like corals they often form), look like Polyps, owing to the series of slen- der ciliated organs surrounding the mouth, as represented in Figs. 395, 395 a ; 395 is magnified about 8 times ; and 395 a represents the animal showing its stomach at s, and the flexure in the ali- mentary canal, with its termination alongside of the mouth. The coral consists of minute cells either in branched, reticulated, or incrusting forms. They are often calcareous ; and such were com- mon in the Silurian, and still occur. Eschara, Flustra, fietepora, are names of some of the genera. The Oysters in the market often have their shells encrusted with large groups of the minute cells of Bryozoans. Fig. 431 represents a membranous species (called Gemellaria loricata) ; b is the moss- like coral, natural size ; and a a portion of a branch, enlarged, showing the cells. 431. BBYOZOAN, Gemellaria loricata. 5. Echinoderms. Echinoderms, while eminently radiate in the adult stage, in the young have bilateral symmetry ; and a few species never get beyond the form of the young. The exterior is more or less calcareous, often furnished with spines. They have distinct nervous and respiratory systems and also a complete digestive system. The name alludes to the spines over the surface in a prominent part of the species, and is from echinus, a hedgehog. The following are the subdivisions : 1. Holothurioids (Sea-slugs, Sea-cucumbers). Having the exterior soft, and through- out extensile or contractile, and the body elongated ; mouth at one end surrounded by a wreath of branched tentacles. 428 HISTORICAL GEOLOGY. 2. Echinoids (Sea-urchins) . Having a thin and firm hollow shell, covered externally with spines (Fig. 441) ; form, spheroidal to disk-shape ; the mouth below, at or near the center, as the Echinus. Fig. 441 represents an Echinus partly uncovered of its spines, showing the shell beneath, and 432 another, wholly uncovered. The shell consists of polyg- onal pieces, in 20 vertical series, arranged in 10 pairs, except in species of the Paleozoic. Five of these 10 pairs are perforated with minute holes, and are called the ambulacral series (a in Fig. 441 represents one pair) ; and the other 5, alternating with these, are called the inter-ambulacral (&). The inter-ambulacral areas have the surface covered with tubercles, and the tubercles bear the spines, all which are movable by means of muscles. The ambulacral have few smaller tubercles and spines, or none ; but over each pore (or rather each pair of pores) the animal extends out a slender fleshy tentacle or feeler, which has usually a sucker-like termination and is used for clinging or for loco- motion. In Fig. 432, the inter-ambulacral areas are broad and the plates large, but the ambulacral are narrow and the plates indistinct. The wow^-opening is situated below, at the center of radiation of the plates. The anal opening in the Regular Echinoids (Fig. 441) is in the opposite or dorsal area or center of radiation. Around the dorsal area there are 5 minute genital openings. In the Irregular Echinoids constituting a large group the anal opening is to one side of this dorsal center of radiation, and often on the ventral or under surface of the animal. In Fig. 432, for example, the anal opening is marginal instead of central, while the genital pores are around the dorsal center, as in the Eegular Echinoids. To one side of the dorsal center in the Regular Echinoids, there 432-434. 434 ECHINODERMS. Fig. 432, an Echinus without its spines, the Clypeus Hugi of the Oolyte; 433, the living Pentacrinus caput-raedusse of the West Indies (x ) ; a,b, c, d, outlines of the stems of different species of Pentacrini; 434, plates composing the body of the Crinoid, Batocrinus longirostris. is a small porous prominence on the shell, often called the madreporic body, from a degree of resemblance in structure to coral. In some of the Irregular Echinoids, this madreporic body is in the center of dorsal radiation. The ambulacral areas are sometimes equally perforated throughout their length. But in other cases only a dorsal portion is conspicuously perforated, as in Fig. 432, and, as this portion has in this case some resemblance to the petals of a flower, the ambulacra are then said to be petaloid. A large part of Echinoids have a circle of 6 strong, calcareous jaws in the mouth ; in a portion of the Irregular Echinoids there are no jaws. 3. Asterioids ( Star-fishes') . Having the exterior stiffened with articulated calcareous granules or pieces, but still flexible ; form star-shaped or polygonal ; the viscera extending BRIEF REVIEW OF THE SYSTEM OF LIFE. 429 into the arms ; mouth below, at center ; arms or rays with a groove on the lower side, along which the locomotive suckers protrude through perforated plates ; eyes at the tips of the arms. Ex., the Star-fish, Fig. 442. 4. Ophiuroids (Serpent- Stars'). Having a disk-like body with a star-shaped mouth beneath, and long, jointed, flexible arms, which sometimes subdivide by forking, but never bear pinnae, and have no grooves along the under side, nor eyes at the slender tips. The viscera do not extend into the arms ; the ovarial openings are slit-like, between the bases of the arms ; and there is no anal orifice. The disk part is homologous with the whole of an Asterioid. 5. Crinoids (including Comatulids}. Like ordinary star-fishes in having flexible arms or rays ; but the calcareous secretions of the rays and body constitute a series of closely fitting solid pieces, and the viscera are confined to the body portion. The rays are 435-444. 44d RADIATES. Figs. 435-444. 1. Polyps : Fig. 435, an Actinia; 436, a Coral, Dendrophyllia ; 437, a Coral of the genus Gorgonia. 2. Hydrozoans : 438, a Medusa, genus Tiaropsis; 439, Hydra (x 8) ; 440, Syn- coryne. 3. Echinoderms : 441, Echinus, the spines removed from half the surface (x ) ; 442, Star-fish, Palaeaster Niagarensis ; 443, Crinoid, Encrinus liliiformis ; 444, Crinoid, of the group of Cystoids, Cal- locystites Jewetti. often very much subdivided, and bear pinnae, in which the generative organs are situated. The species are mostly fossil, and are among the earliest in geological history. A few kinds still live in the ocean mostly below 20 fathoms, some at great depths. There are 3 tribes of Crinoids : 1. The Brachiates (Encrinites) . Having a radiate structure, and arms proceeding from the margin of the disk ; also generally a stem, consisting of calcareous disks, by which, when alive, they are attached to the sea-bottom or some support, so that they stand in the water and spread their rays, like flowers, the mouth being at the center of the flower. Crinoids are represented in Fig. 443, Fig. 433, and Fig. 30 on page 58. The second and third are living species from the West Indies, found at depths below 20 fathoms. The rays open out, when alive, and then the animal has its flower-like aspect. The little pieces that make up the stem, looking like button-molds, are either circular, as in Fig. 443 a, or 5 sided, as in Figs. 433 a, 6, c, d. Under the Crinidea fall the Comatulce (Antedon, etc.), which are free when adult, but have jointed cirri proceeding from the back surface for attachment. 430 HISTORICAL GEOLOGY. 2. The Blastoids (Pentremites, etc.). Having a symmetrical ovoidal body, with 5 petal-like ambulacra meeting at the summit, without proper arms, and attached by a stem like that of the Encrinites. 3. The Cystoids (from the Greek for a bladder}, Fig. 444. Arrangement of the plates not often regularly radiate. Arms, when present, proceeding from the center of the sum- mit instead of the margin of a disk ; in some, only 2 arms ; in others, replaced by radiat- ing ambulacral channels, which are sometimes fringed with pinnules. In ancient Crinoids, the arms are not generally free down to the base, but there is a union of their lower part, either directly or by means of intermediate plates, into a cup- shaped body or calyx (as in Fig. 443, and also Figs. 995, 999, under the Subcarboniferous period, page 640). In Fig. 434, the plates of one of these cups, in the species Batocrinus longirostris H., are spread out, the bottom plates of the cup being at the center. The plates, it is seen, are in 5 radiating series, corresponding to the 5 rays or arms of the Crinoid, and between are intermediate pieces. The 3 plates numbered 1 are called the basal, as the stem is articulated to the piece composed of them ; 3, 3, 3 are the radial ; 4, 4, supra- radial ; 5, brachial, situated at the base of the arms ; 7 are immediate plates, called inter- radial ; 8, another intermediate, the inter-supraradial. Sometimes, in other Crinoids, there is another series of plates, at the junction of the plates 1 and 3, called sub-radial. Finally, the anal opening of a Crinoid is situated toward one side of the disk, it being lateral, as in the Echinoid in Fig. 432; and the intermediate group plates numbered 10 are called the anal. In the Cystoids, the aperture is generally lateral and remote from the top, as in Fig. 444, while the arms often come out from the very summit. The Cystoids are also peculiar in what are called pectinated rhombs (see Fig. 444) ; that is, rhombic areas crossed by fine bars and openings ; the use of them is uncertain, though they are probably connected with an aquiferous system and respiration. 6. Coelenterates. The Ccelenterates are distinguished from Echinoderms by the existence of only one opening to the digestive system, the mouth. Moreover, the tentacles and other parts are never normally a multiple of 5, but either of 4 or 6 ; of 4 in Hydrozoans and 4 or 6 in Polyps. 1. Hydrozoans (Acalephs, Medusae, Jelly-fishes, Hydroids). Having the body, in the adult stage, usually nearly transparent or translucent, looking jelly-like ; and internally a stomach-cavity, with radiating branches. Ex., the Medusa, or Jelly-fish (Fig. 438), which generally floats free, when in the adult stage, with the mouth downward. The Hydra and allied species are here included. Most marine Hydroids at times produce sexual buds, which, in many species, break away and become free jelly-fishes. Many of the Hydroids make corals, and hence are common as fossils. Fig. 439 represents a Hydra enlarged, with a young one budded out from its side. Some species of the group those of the Sertularia tribe form delicate chitinous corals, such as are represented in Fig. 445, in which each notch on the little branchlets corresponds to the cup-shaped cell from which an animal protrudes its flower-shaped head, (a is the Sertularia abietina; 6, S. rosacea; and a', 6', portions of branches enlarged.) The interior cavities HYDROZOANS. Figs, a, a', Sertularia abie- tina; b, b', 8. rosacea. BRIEF REVIEW OF THE SYSTEM OF LIFE. 431 of each animal communicate freely with the tube in the stem ; and in this they differ from Bryozoans, whose groups have no tubular axis. The ancient Graptolites (some of which are represented on page 610) are supposed to have been of this nature. Others secrete calcareous corals of large size, and are called Millepores (because the minute cells from which the animals protrude are like pinpunctures in size, and very numerous over the surface of the coral). The Millepores are common in the West Indies and other coral seas. The minute animals of a Millepore have nearly the form represented in Fig. 440, which represents a species of another genus, called Syncoryne. There are hence stony corals made by Polyps, by Hydrozoans, and by Bryozoans ; and others that are made by sea-plants, as explained beyond. 2. Actinozoans, Anthozoans, or Polyps. Fleshy animals, like a flower in form, having above (Figs. 435, 436) a disk, with a mouth at center, and a margin of tentacles ; internally, a radiated arrangement of fleshy muscular plates ; and living for the most part attached by the base to some support. Ex., the Actinia, or Sea-Anemone, and the ani- mals of ordinary corals. There are two groups of coral-making Polyps : 1. ACTINOIDS (Zoantharia) (Figs. 435, 436), which make the ordinary corals. The rays or tentacles of the Polyps are naked, that is, without a fringe of papillae. In the Madreporaria, the number of tentacles is a multiple of 6 ; in the Cyathophylloids or Tetra- coralla, a multiple of 4. The coral is secreted within the Polyps, and not outside as in the case of shells. It is usually covered with radiate cells, each of which corresponds to a separate Polyp in the group. The calcareous rays or septa are made in the spaces between the fleshy partitions in the interior of the Polyp. The material is calcium carbonate (limestone) ; and it is taken by the Polyp from the water in which it lives, or from the food it eats. 2. ALCYONOIDS (Alcyonaria} (Fig. 437), or those of the Gorgoniaand Alcyouium corals. The rays of the Polyps are 8 in number, and fringed. Fig. 437 represents a part of a branch of a Gorgonia (Sea-Fan), with one of the Polyps expanded. The branch consists of a horn-like axis and a fragile crust. The crust is partly calcareous, and consists of the com- mon tissue (coenenchyma) by which the Polyps are united together ; the axis is secreted by the inner surface of the crust. The precious coral used in jewelry comes from the shores of Sicily and some other parts of the Mediterranean, and belongs to this Alcyonoid division. It is related to the Gorgonias, but the axis is red and stony (calcareous) instead of being horny ; and this stony axis is the coral so highly esteemed. A few species make calcareous corals much like those of the Actinoids without any separate crust. 7. Spongiozoans. 1. The Sponges (Porifera) are mostly complex groups of animals, having internal membranes composed of ciliated cells resembling the collared Flagellate Protozoans. Some simple sponges are of one Zooid only. The groups secrete, excepting in one tribe, the gelatinous Sponges, or Halisarcoids, a framework (1) of horny fibers, or (2) of horny fibers set with siliceous spicules ; or (3) of siliceous spicules or fibers ; or (4) of calcar- eous spicules or fibers. Of these 4 kinds, the first are the Corneous Sponges of com- merce; the second, the Corneo- siliceous, a harsh and more brittle kind; the third, the Siliceous ; the fourth, the Calcareous or Calcispongice. Some of the forms of the spicules of the corneo-siliceous and siliceous sponge-spicules are shown in Figs. 446-460, by Hinde. All these spicules were found by Hinde in powder filling a single small cavity in flint from Norfolk, England. All are much enlarged. The Hexactmellid Sponges are siliceous and have the framework made up of spicules with rays crossing at right angles, making it 6-rayed at the crossing ; they are mostly from great depths ; Tetractinellids are 4-rayed. But simple forms accompany the more complex. The Sponges occur at all depths in the ocean and are very various in shape. 432 HISTORICAL GEOLOGY. The hexactinellid sponge Euplectella (Vemis's Elo wer-Basket) , Fig. 29, page 57, which looks as if made of a network of spun glass, comes from a depth of 50 fathoms in the East Indies. The fossil Diclyophyton and Euphantcenia are related to Euplectella, as shown by Whitfield. Sponges are mostly marine ; but a few, like the Spongillce, grow in fresh water and contribute siliceous spicules to peat and other swamp deposits. The death and decay of Sponges adds largely to the silica of the sea-bottom. 446-460. 45T 458 SPONGB-SPICULES. Figs. 446-449, Geodia or allied; 450, Globostellate spicule, near Geodia ; 451, Stel- letta; 452, Carterella; 453, 454, Tetractinellid spicules ; 455, Ventriculites, Hexactinellid; 456, Ragadinia annulata ; 457, Tisiphonia ; 458, the same? ; 459, Racodiscula ; 460, Plinthosella squamosa. Figs. 450, 453, 454 (x 10); 456 (x68); others (x34). Hinde. 8. Protozoans. Among Protozoans only the Khizopods and Radiolarians have prominent importance. 1. Rhizopods (Foraminifers) . Species mostly minute, often forming shells; the shells, with few exceptions, not larger than the head of a pin : but the groups sometimes having the shape of disks an inch in diameter, and occasionally of large massive forms. They have usually calcareous shells called Foraminifers (from foramen), and these have contributed largely to the formation of limestone strata. They consist of 1 or more cells ; and the compound kinds present various shapes, as illustrated in Eigs. 461-474. The arrangement in a group is usually alternate or spiral. Others make a shell or test by the agglutination of grains of sand or other material. Figs. 461-474 RHIZOPODS, much enlarged (excepting 473, 474). Fig. 461, Orbulina universa ; 462, Glo- bigerina rubra; 463, Textularia globulosa Ehr. ; 464, Rotalia globulosa ; 464 a, Side-view of Rotalia Boucana ; 465, Grammostomum phyllodes Ehr. ; 466, a, Frondicularia annularis ; 467, Triloculina Jose- phina; 468, Nodosaria vulgaris; 469, Lituola nautiloides; 470, a, Flabellina rugosa ; 471, Chrysalidina gradata ; 472, a, Cuneolina pavonia ; 473, Nummulites nummularius ; 474 a, b, Fusulina cylindrica. All but the last two magnified 10 to 20 times. BRIEF REVIEW OF THE SYSTEM OF LIFE. 433 475. Globigerinae, with Diatoms, from a deposit off Alligator Reef (x 15). A. Agassiz. Fig. 461 is a 1-celled species ; the others are compound, and contain a number of exceedingly minute cells. A few are comparatively large species, and have the shape of a disk or coin, as Fig. 473, a Nummulite, natural size ; the figure shows the interior cells of one half : these cells form a coil about the center. Orbitoides is the name of another genus of coin-like species. Fig. 474 a is a species of Fusu- lina, a kind nearly as large as a grain of wheat, related to the Nummulites ; 474 b is a transverse view of the same. This is one of the ancient forms of Rhizopods, occurring in the rocks of the Coal formation. Rhizopods of the genus Globigerina and other forms have been already mentioned (page 144) as the chief constituents of the calcareous ooze or mud making much of the sea-bottom. Fig. 475 repre- sents an aggregation of Globigerinse with Diatoms, found at a depth of 880 feet, off Alligator Reef, near the south coast of Florida, as figured by A. Agassiz. Each Rhizopod cell is occupied by a separate animal or zooid, though organically connected with the others of the same group or shell. The animal is of the simplest kind, having no mouth or stomach, and no members except slen- der processes of its own substance, which it extrudes through pores in the shell, if it have any. The name Rhizopods comes from the Greek for root- like feet, in allusion to the root-like processes they throw out. Some of the species not secreting shells (as in the genus Amoeba} have been seen to extemporize a mouth and stomach. When a particle of food touches the surface, the part begins to be depressed, and finally the sides of the depression close over the particle, and thus mouth and stom- ach are made when needed ; after digestion is complete, the refuse portion is allowed to escape. The shells of some Rhizopods do not con- sist of distinct cells : the aggregate living mass secretes carbonate of lime, without retaining the distinction of the zooids. This is the case, as Carpenter has observed, in the Nummulite- like genus Orbitolites. Some species make large coral-like masses instead of small shells. 2. Radiolarians (Polycystines). Se- crete siliceous shells which are symmetrically radiate or circular. Three species, from the Barbados, are represented in Figs. 476 to 478. Fig. 476, Lychnocanium lucerna Ehr. ; Fig. 477, Eucyrtidium Mongolfieri Ehr. ; Fig. 478, Halicalyptra fimbriata Ehr., the first two magnified 100 diameters, the last about 75. From these deeply concave forms, there are gradations in one direction to disks with con- cave centers, and to flat disks, both with plain and pointed borders, and in the other direction to elongate, conical, and spindle-shaped forms. Others have the shape of a flattened* cross; another is an open diamond, with narrow diagonals and periphery. The disks have a concentric, and not a spiral, structure, and thus are unlike those of Nummulites. The annexed figure represents a minute spherical species of Radiolarian a jelly-like globule bristled with spicules which sometimes beclouds the water in the Pacific and East Indian seas (Sphcerozoum orientale D.). DANA'S MANUAL 28 476. 477. 478. 476, Lychnocanium lucerna ( x 100) ; 477, Eucyr- tidium Mongolfieri (x 100) ; 478, Halicalyptra fimbriata (x 75). 479. 434 HISTORICAL GEOLOGY. VEGETABLE KINGDOM. A cell with its contents is the fundamental element of a plant, and the simplest and lowest plants are the microscopic unicellular kinds ; that is, those made of a single cell, or a few in a series, as the lower ALG.E and lowest FUNGI. From these, the grade in species rises through larger Algae, and other kinds consisting of cellular tissue, as the FUNGI, HEPATICJE, and MOSSES, to those which contain also vascular tissue, but subordinately to the cellular as the FERNS, EQUISETA, LYCOPODS. The kinds thus far mentioned are Cryptogams, or the Flowerless plants. The remaining plants, or those producing true flowers and seeds, are called Phceno- gams. They consist of cellular tissue and woody fibers ; and also, of vascular tissue in the larger part of the species. PH^ENOGAMS. Phsenogams are divided into two sections, on the basis of the structure of the embryo or seed, and the growth. In the Exogens, the embryo consists of two or more parts called cotyledons. Further, as the name Exogen implies (it signifying growth by the out- side), there is, after the first year, with rare exceptions, an annual addition of a layer of woody tissue between the wood and bark. In a section of an exogenous stem more than a year old, the wood has, consequently, rings of growth. In the Endogens, the seeds consist of a single cotyledon. Besides, there are no rings of growth, and no separable bark ; growth goes forward mainly by the pushing out of buds at the extremity of the stem or of its branches. The structure of the wood is said to be endogenous. 1. Exogens. Exogenous species are of two divisions called Gymnosperms and Angiosperms. 480. Cycas circinalis, 1. Gymnosperms. In this inferior division of the Exogens, the seeds are naked and there is no stigma. The fruit often consists of a cone made of scales with the seeds beneath the scales. They are called Gymno- sperms (from the Greek for naked seed) in allusion to the naked or uncovered state of the seed. The inferiority to other Phaenogams is manifested not only in the simple character of the flower, but also in the wood, which contains no vascular tissue, and this inferiority accords with the fact that they preceded geologically other Phse- nogams. The inferior division, that of Cycads, is now few in species, but for- merly included a large part of the com- mon forest trees. The Cycads (with the related Zamise) are peculiar in combining the structure and fructifi- cation of the Gymnosperm with the habit of a Palm, and the method of uncoiling the leaves as they are devel- oped which belongs to Ferns. The BRIEF REVIEW OF THE SYSTEM OF LIFE. 435 483. 481. 482. wood of the modern tree has a very large pith abounding in starch, surrounded by one or more rings of wood, each the result of several years' growth. The ordinary "Evergreen" trees, as the Pine, Spruce, Arbor Vitae, Yew, belong to the second and higher subdivision, the Conifers, so-called because the flowers and fruit ordinarily have the form of cones. In the Pine family the fruit is a cone ; but not so hi the Yews. The Salisburia, or Ginkgo, a tree with short and broad, somewhat fanlike leaves, is generally referred to the Yew family, though having some relations to the Cycads. The woody fiber of the Conifers is marked with circular disks as in Figs. 481, 482 ; fossil woods of the order may thus be distinguished, and genera may often be distinguished by their ar- rangement. Another aberrant group, the Gnetacece, in- cludes the genera, Gnetum, Ephedra, and Wei witschia ; and the last, of which only one species exists, and that in Africa, approaches the Angiosperms, in its flower, "the staminal flower con- taining a rudimentary ovule." But it has the broad strap-like leaves of the ancient Cordaites, and also, as the Fig. 483 shows, the winged form of fruit characteristic of the Carboniferous Cardiocarpus. 2. Angiosperms. The higher Exogens, or the Angiosperms, have the seeds covered ; the flowers perfect, the wood consisting largely of vascular tissue as well as woody fibers. Examples are the Maple, Elm, Apple, Chestnut, Rose. 2. Endogens. The Endogens are represented by the Palm, Rattan, Smilax, Grasses, Orchids. A section of a woody stem, as that of a Rattan (a species of Calamus) or Smilax, shows the ends of woody fibers and ducts. The leaves are parallel-veined instead of net-veined, and not toothed, and the parts of the flower are commonly in threes. Circular disks on the woody fibers of Conifers. Fig. 483, Welwitschia mirabilis, showing trans- verse section of fruit, with the outline of the fruit finished in dotted lines. CRYPTOGAMS, OR FLOWERLESS PLANTS. 1. The Higher Cryptogams, or Acrogens. The Acrogens consist of cellular tissue with more or less of fibro-vascular tissue, and are capable of upward growth, whence the name from fapov, top, and yewaw, grow. The lowest species have special interest in the geological history of plants. They are called Rhizocarps (root-fruited) from the position of the fruit at the base of the stem, or at the root. The figures represent, half the natural size, species of three of the very few forms now existing. They show the position of the nuts, and the unlikeness of the species in habit to most Cryptogams. Fig. 486, of Salmnia natans, represents a section of the plant showing only one of the pairs of leaves in the floating plant. 436 HISTORICAL GEOLOGY. The other principal divisions of the Acrogens are the following : (1) Equiseta, or Horse-tails. The existing species have hollow- jointed, slender stems ; the leaves arranged in whorls at the nodes ; and the cone-like fructification at the ends of the stems. Ancient species grew with stout trunks to a height of 30 feet or more. (2) Lycopods, or Ground-Pines. The Lycopods have many leaves, with the habit of 484. 485. RHIZOCARPS. Fig. 484, Pilularia globulifera, with fructification; 485, Marailea quadrifolia, with an enlarged view of the nut; 486, Salvinia natans, part of plant. All half the natural size, Luerssen. a Spruce or Pine ; they are small plants now, but in the Coal era grew up as trees, 30 to 90 feet in height. (3) Ferns. Modern Ferns sometimes make trees 20 to 30 feet high. 2. The Lower Cryptogams. The Lower Cryptogams consist of cellular tissue alone, are: The principal groups 1. Mosses. Green, terrestrial plants having delicate leaves along the slender stems ; limited to a few inches in the height of the living part of stems. Closely related to the Mosses are the Hepaticce, or Liverworts. 2. Lichens. Dry plants, of gray, brown, and black colors, making fronds without leaves, which spread over the surfaces of rocks, the outer bark of trees, etc. 3. Fungi. Succulent plants, gray to brown in color, and never green ; without foliage ; grading down to Molds, which consist of strings and groups of cellules, and to Bacteria and other microscopic, free-swimming, unicellular kinds. 4. Algae, or Seaweeds. The water-plants are green to brown in color, and contain more or less chlorophyl. They graduate downward from ordinary seaweeds to micro- scopic, free-swimming, unicellular kinds. Of like grade with the unicellular species are other kinds having the form of threads or groups of threads, each thread consisting of a series of cells. The lowest groups include the species of Protococcus, of which P. nivalis is red and gives the red color to the snow or ice in some Alpine regions. The Diatoms BRIEF REVIEW OF THE SYSTEM OF LIFE. 437 having siliceous shells are others. A few species are represented in Figs. 487-493. Another group is that of Desmids, which consist of one or a few greenish cells, and secrete little or no silica. They are related to the common Conferva (frog-spittle) of fresh-water pools. Other calcareous kinds take delicate branching forms, as the Corallines ; or more stony forms, like those of Corals, but destitute of surface cells, as the Nullipores ; or sponge-like or concretion-like forms, as the cal- careous Algse of the Yellowstone Park. Some 487. related to the last-mentioned occurring in warm waters secrete silica. There are also the minute Coccoliths over the ocean's bottom in deep or shallow waters ; they are so named from the Greek for seed and stone. 488 488-493. Figs. 487-493, DIATOMS highly magnified; 487, A group of fossil Diatoms; 488, Pinnularia peregrins, Richmond, Va. ; 489, Pleurosigma angulatum, id.; 490, Actinoptychus senarius, id. ; 491, Melosira eul- cata, id. ; a, transverse section of the same ; 492, Grammatophora marina, from the salt water at Stoning- ton, Conn.; 493, Bacillaria paradoxa, West Point. The common leathery seaweeds of the seacoast, or the Fucus division, include the Sargassum of the Atlantic, the air-cavities in which enable it to float. CEPHALIZATION, A GENERAL PRINCIPLE BEARING ON AND GRADE IN THE ANIMAL KINGDOM. SYSTEM Since an animal has, typically, an anterior nervous mass or ganglion determining the position of the head, and antero-posterior conditions in growth, a greater or less subordi- nation to the head in the arrangement of its organs should naturally be looked for. Degree of structural subordination to the head and of concentration headward in body-structure, is referred to under the term Cephalization. The principle is illustrated in the class of Crustaceans, with special clearness and large distinctive characters, on account of the fewness of the species and their size. Some preliminary explanations are here first given respecting Worms, and then the facts from the class of Crustaceans. 1. Worms. An example of a low decephalized condition among Articulates exists in the Tape-worm, Tcenia solium, one of the lowest of the so-called Worms. It grows and elongates by the multiplication of segments (by budding), until their number is sometimes several hundred, the new segments forming successively just behind the head. The head has its very small nervous ganglion, from which slender nerves pass backward ; so that in growth and nerves it is an individual. But it has no mouth, and the body no stomach or intestine. Instead of this, each segment is so far complete in its individuality that it takes its independent nutriment, and has its own reproductive system ; and if separated from the rest of the series, it has all that is required for propagating the species by ova. Here 438 HISTORICAL GEOLOGY. decephalization and a multiplicate or nearly limitless segmentation are extreme. There is no lower extreme, except in that of the compound mass of the sponge or the polyp, where -a head fails entirely. In the higher typical Worms, the Annelids, the many segments of the body have a separate nervous ganglion as an enlargement of the nervous cord, or pair of cords, that passes posteriorly from the cephalic ganglion, giving it a degree of independence. But the head has its mouth, and the body its intestine and reproductive system, so that the structure is one in system of growth and reproduction. Yet the number of body-segments varies greatly, it being not often fixed even for the species of a genus ; and all of the segments behind the head participate alike essentially in the work of locomotion. The body structure in Worms is, therefore, multiplicate, and greatly decentralized, and loco- motion is of the diffuse kind. Moreover, jointed limbs are wanting. 2. Crustaceans. Crustaceans contrast strongly with the Worms, high or low. (1) The body consists of a head (which, as in other animals, includes the mouth as well as the organs of the senses), a thorax furnished with limbs, and an abdomen. (2) The number of body-segments, in typical species, is limited, instead of being multiplicate, it not exceeding 20; 6 of these segments pertain to the abdomen, and 14 to the thorax and head. On differences in the arrangement and functions of the parts of the structure, exemplifying degrees in cephalization, is based the accepted system of classification in Crustaceans. This system subdivides the typical species into (1) Decapods, or the 10-footed, and (2) Tetradecapods, or the 14-footed ; and each of these tribes into two subordinate groups, Brachyurans and Macrurans for the former, and Isopods and Amphipods for the latter. Decapods and Tetradecapods. In the Decapods (1) the head includes 9 body- segments the 3 anterior bearing the organs of the senses, the eyes, and 2 pairs of antennae, and the remaining 6, the jointed mouth organs ; and (2) the thorax, comprising the remaining 5 segments of the cephalothorax, bearing 5 pairs of feet. In the Tet- radecapods, the head corresponds to only 7 body-segments, and has, therefore, but 4 pairs of mouth organs, while the thorax includes 7 segments and bears 7 pairs of feet. In other words, the anterior 2 pairs of feet of the Tetradecapods are pairs of mouth organs in the Decapods. There is thus a transfer forward of legs to the mouth series on rising from the Tetradecapod tribe to the Decapod. It is a case of concentration headward in the structure, or of higher cephalization. The two tribes also differ in the mean size of the animals, Decapods having, on an average, 100 times the bulk of Tetradecapods. We pass now to the two subdivisions of the Decapods and Tetradecapods. Brachyuran and Macruran Decapods. A Macruran Decapod, as exemplified in a Lobster, Prawn, or Shrimp, has (1) an elongate, loosely compacted body, with the abdomen nearly as long as the cephalothorax, and in some species several times longer ; (2) the abdomen is the most powerful organ in locomotion ; (3) the thoracic feet are feeble in locomotion ; (4) the outer mouth organs are foot-like, free, and long ; (5) the antennae are sometimes a foot or more long. The Brachyuran, as the common Crab, has, on the contrary, (1) a short body, it being seldom longer than broad ; (2) the abdomen in males is very small and narrow, it doing no service in locomotion, but, instead, lying confined in a groove on the under side of the body, so that the animal is almost comprised within the first 14 of the normal 20 segments of the Crustacean ; (3) the thoracic feet, or those of the posterior 5 of these 14 segments, are the sole organs of locomotion ; besides (4) the mouth organs are small, and closely stowed away together within, or over, a shallow cavity, which is covered by the outer pair, as an operculum ; and (5) in harmony with the general com- pactness of structure, the antennae are very small, seldom exceeding an inch in length. BRIEF REVIEW OF THE SYSTEM OF LIFE. 439 Between the Macrurans and the Brachyurans there is the grand distinction that the former are long extended posteriorly, and urosthenic, as regards locomotion (or strong in the posterior extremity, that is, the abdomen), while the latter have short bodies, gathered in closely and compactly behind the cephalic ganglion, and are podosthenic, thoracic feet being the only locomotive organs. In rising from the Macruran to the Brachyuran there is a forward transfer in the general structure and in the locomotive function, and thus a great rise in degree of cephalization. Under each of these two types of Decapods a wide range of grade is structurally indi- cated, illustrating degrees in cephalization. Isopod and Amphipod Tetradecapods. The Isopods and Amphipods are brachyuran and macruran Tetradecapods, for the series of Tetradecapods is closely parallel with that of the Brachyurans and Macrurans among Decapods. The Isopods have a compact body, a short abdomen, which is not used in locomotion, with relatively short antennae, while the Amphipods have a longer body more loosely put together, usually long antennae, an elongate abdomen, and the abdomen is the chief organ of locomotion that by which the little animal makes its leaps. Here, again, the lower are the urosthenic and decephalized species, the higher the podosthenic and more cephalized species. Entomostracans. Below the Tetradecopods come the Entomostracans. A part of the Entomostracans are multiplicate species, the Phyllopods ; and in this character, both in the Entomostracans of Decapod and of Tetradecapod relations, they show out the ancestral worm, and thereby low-grade cephalization. The structure is eminently primitive and was especially characteristic of early Paleozoic Articulate life. Besides these there are the simply defective forms among Entomostracans, representa- tive of different stages in embryonic development. Defective forms of similar character occur even among the Macruran Decapods ; for some of the inferior shrimp-like species have one or two of the posterior segments of the thorax without legs, or even wanting ; and in such species (called Schizopods), the thoracic legs have the form characterizing a young stage in development. But among the Entomostracans, the defective stage appears in more extreme forms. The limbs are partly natatory ; the mouth organs are often either pediform or natatory, or of more abnormal forms ; and the abdomen has no appendages except ovarian attached to the basal portion and a caudal pair pertaining to the sixth segment. The preceding remarks on the bearing of the principle of cephalization on system and grade in Crustaceans cannot be true for one branch of the Animal Kingdom without hav- ing a wide significance. See, for other examples, Historical Geology, pages 721, 723. This subject has much interest in connection with the successional lines in the animal life of the globe which geology has brought to light. But the preceding remarks are not to be understood as intimating anything with regard to the origin of species. There was no such reference in the author's first presentation of the views in 1852. 1 At that time the idea of evolution by natural causes had scarcely an advocate ; for Darwin's work did not appear until 1859. Neither are the facts now to be regarded as adding to the causes of derivation. This much, however, may be learned from them : 1. Whatever the natural causes or methods concerned in evolution, organic conditions have determined lines, limits, and parallel relations, in accordance with the principle of cephalization. 2. In the evolution of the animal kingdom a " tendency upward " is a necessary con- sequence of the presence of a cephalic nervous ganglion or brain. - 1 Report on Crustacea of the Wilkes Expl. Exped. around the World, 1618 pp., 4to, with a folio Atlas of 96 plates. In the papers on cephalization published in the American Journal of Science, eleven to twelve years later, and subsequently a summary in 1876, the principle of cephalization was illustrated by reference to other classes of animals ; but the speculative conclusions added in those papers are not all in accord with the author's present judgment. I. ARCH^AN TIME. SYNONYMY. Primitivgebirge, Urgebirge, Lehmann, 1756, Werner. Urformation. Ur- gneissformation. Azoic Rocks, Murchison and De Verneuil, 1845, Russia in the Urals, i. 10. Fundamental Gneiss, Lewisian Gneiss, and later, Laurentian Gneiss, after Logan, Murchison. Mona Series, De La Beche, Geol. Obs., p. xxxii, 1851, for crystalline rocks of Anglesea, etc. Azoique, D'Orbigny, Pal. et Geol., 1851. Azoic System, J. D. Whitney, Rep. of Foster and Whitney, Geol. Lake Superior Land District, Part ii., pp. 8-35, 1851, the system comprising rocks north of Lake Superior, others south of the lake, also others in the Adirondacks, etc. Laurentian and Huronian, Logan, 1852, 1854. Azoic (following Whitney, with Logan's subdivisions), first edition of this Geology, 1863. Archaean, D., Amer. Jour. Sc., viii. 213, 1874, and second edition Geology, 1875. Eozoic, J. W. Dawson, 1875. Crystallophyllian, Belg. Geologists of the Internat. Congr. Geol., 1885. Archaean time commences geologically with the earth as a solid globe, or one having at least a solid exterior ; for only the conditions of such a globe are within reach of geological investigation. By following the lead of ascer- tained law in physics and chemistry, and the suggestions of astronomy, and also such analogies as are afforded by later geological history, some probable conclusions may be drawn with reference to earlier time. But this is not the place for their discussion, except so far as to state the principal steps of progress. The following is a general view of the natural subdivisions of Archaean time. I. The Astral aeon, as it has been called, or that of the fluid globe having a heavy vaporous envelope containing the future water of the globe or its dissociated elements, and other heavy vapors or gases. II. The Azoic aeon. Without life. 1. The LITHIC ERA : commencing with the earth a solid globe, or at least solid at the surface; the temperature at the beginning above 2500 F. ; the atmosphere still containing all the water of the globe (amounting to 200 atmospheres, according to Mallet, 1880), all the carbonic acid now in limestone and that corresponding to the carbon now in carbonaceous substances and organic sub- stances (probably 50 atmospheres), all the oxygen since shut up in the rocks by oxidation, as well as that of the atmosphere and of organic tissues. The time when lateral pressure for crustal dis- turbance and orographic work was begun ; when " statical meta- morphism" or that dependent on heat of a statical source, the earth's mass and the vapors about it, began. 2. The OCEANIC ERA : commencing with the waters condensed into an ocean over the earth, or in an oceanic depression, with finally some emerging lands, the temperature perhaps about 500 F., if the atmospheric pressure was still 50 atmospheres. The first of tides and the beginning of the retardation of the earth's rotation. Oceanic waves and currents and embryo rivers begin work about 440 ARCHAEAN TIME. 441 the emerged and emerging lands ; the large excess of carbonic acid and oxygen in the air and water a source of rock-destruction ; before the close of the era, the formation of limestones and iron- carbonate by chemical methods, removing carbonic acid from the air and so commencing its purification ; the accumulation of sedi- ments without immediate crystallization or metamorphism, and thereby the beginning of the earth's supercrust. III. The Archaeozoic aeon. Life in its lowest forms in existence. 1. The ERA OF THE FIRST PLANTS : Algae, and later of aquatic Fungi (Bacteria), commencing with the mean temperature of the ocean at possibly 150 F., since plants now live in waters up to and evsn above 180 F. Limestones formed from vegetable secretions, and silica deposits from silica secretions ; iron-carbonate, and perhaps iron oxides formed through the aid of the carbonic acid of the atmosphere and water ; large sedimentary accumulations, where conditions favored, thickening the supercrust. 2. The ERA OF THE FIRST ANIMAL LIFE : mean temperature at the beginning probably about 115 F., and at the end 90 F., or lower ; limestones and silica deposits formed from animal secretions ; deposits of iron-carbonate and iron-oxides continued ; large sedi- mentary accumulations. The sedimentary or stratified beds of Archaean time are the oldest and most obscured parts of the geological record. Sooner or later in the Arch- aeozoic era "dynamical metamorphism" began, or metamorphism dependent on heat from a dynamical source, that is, heat generated by movements in the thickening crust, aiding the heat still in the earth's mass, or statical heat. Thereby, during a crisis of upturning, the thick accumulations of sediment became metamorphic or crystalline ; but the statical heat was still so great that the temperature was easily made that of fusion, and conse- quently the fusing of fusible sedimentary beds took place and outflows through openings or fissures of granite, syenyte, dioryte, gabbro, and other like rocks, derived severally from granitic, syenytic, diorytic, and gabbronitic or related sediments ; but deep-seated igneous effusions may not have been common, for strains in a thin, rather hot supercrust might extend little below it, and, moreover, igneous ejections from a deep-seated source and through volcanoes reached their maximum in the later part of geological time. Although these eras are not marked off in the rocks, there are facts enough to prove that they represent, in a general way, the system of progress in Archaean time. Millions of years must have elapsed during the cooling from over 2500 F. to 500 F. ; a very long era during that from 500 F. to 150 F. ; and another long era during that from 150 F. to 115 F. ; and still another during that from 115 F. to 90 F. Archaean time was long, immensely long. 442 HISTORICAL GEOLOGY. The subdivision of Archaean time into Azoic and Archaeozoic, here used, is the same as that of the edition of 1874, except that Archaeozoic is substituted for Eozoic. The limit- ing temperature of Archseozoic time is doubtful for several reasons, and especially because of the uncertainty as to the destructive excess of carbonic acid in the air and waters, and, therefore, as to the possibility of the existence of life. There is reason to believe that during the progressing consolidation, and long after- ward, when the heat was too great for the existence of limestones, the lime now in the limestones of the globe was, to a large extent, combined with silica, making silicates and especially the lime-soda feldspars, labradorite and oligoclase, the soda being that now in the ocean's waters minerals that may be made artificially by fusing together the ingredients ; and, consequently, that rocks of the basalt and dioryte types, which con- tain these feldspars, were among the most common. Pyroxene was present through the whole era, but hornblende only in the later part ; for pyroxene is easily made at the high temperature of fusion, but hornblende only under aqueo-igneous action at the lower temperature of 800 to 1000 F. The lime silicates would have used up a large part of what is now free silica or quartz, and hence the igneous rocks would have been, to a great extent, without quartz, and, in this respect, like the most of those that come up from the earth's depth through volcanic eruptions. In fact, most volcanic rocks are por- tions of the Archaean mass constituting the earth's interior. Such being the prevailing rocks of the crust, the sedimentary beds would have been largely of like constituents. On the condition of the primeval globe, see further Ebelmen, 1855 ; Bischoff, 1863 ; T. S. Hunt, 1867, 1880. On subdivisions of Archaean time, D., 1892. NORTH AMERICA. DISTRIBUTION OF ARCHJEAN AREAS. Archaean areas, or those whose surface rocks are of Archaean age, and which indicate, therefore, the probable position of the dry land at the close of Archaean time, have their widest distribution in the more northern por- tions of the continents of North America, South America, and Europe. In North America they cover a very large area, situated mostly north of the Great Lakes and the St. Lawrence River, which is approximately V-shaped in its southern part, as shown in the accompanying map. The white areas on the map represent the probably emerged land over the great Archaean continental sea. The great northern area has been estimated to contain more than 2,000,000 square miles. From the region of the Great Lakes a broad arm stretches northeastward to Labrador and beyond, and another, 2000 miles long, northwestward to the Arctic shores. Hudson Bay, 800 miles from north to south and 600 in greatest breadth lies between the arms of the V. The eastern arm of this early dry land of North America has a course nearly parallel to the existing eastern coast-line of the continent, and the western as nearly to the mean direction of the western coast-line. The map is 011 Mercator's projection. The course of the Mississippi River and the outlines of lakes are inserted merely to mark positions. The Archaean area extends south of British America into northern New York, the Adirondack region being a portion of it, and also south of Lake Superior into northern Michigan and Wisconsin. AKCH^EAN TIME. 443 Besides the nucleal area of the continent, there are other areas lying in ranges or chains that are approximately parallel to the arms of the nucleal V. On the Atlantic border, northeastward in general trend. On the Atlantic border there is the long Appalachian protaxis (page 24), extending interrupt- edly from Canada south of the St. Lawrence, along the higher land of Ver- 494. Map of North America at the close of Archaean time, showing approximately the areas of dry land. mont ; eastern Berkshire in Massachusetts ; Putnam, Orange, and Rockland counties in New York, and Sussex in New Jersey, making the Highland Range, which crosses the Hudson between Fishkill and Peekskill ; consti- tuting some ridges in southeastern Pennsylvania; thence continuing south- westward along the " Piedmont " belt, and through Virginia and North Carolina, constituting in the latter state the Black Mountains ; thence into South Carolina and Georgia. It is marked A on the map. To the northeastward, over New England to Newfoundland, there are other parallel ranges, bounding broad valleys or basins, as follows : (1) To the east of the Connecticut valley, at intervals, from Canada to Connecticut. 444 HISTORICAL GEOLOGY. (2) Farther east, from near Chaleur Bay, on the Gulf of St. Lawrence, through New Brunswick, southwest to the coast of Maine (including the Mount Desert rocks) and into eastern Massachusetts. (3) The Acadian Eange, along western Newfoundland and central Nova Scotia; then sub- merged off the coast of Maine and Massachusetts ; then over southeastern Massachusetts, and probably along Long Island. (4) A central Newfound- land range, which may have had a submarine extension along Sable Island and the shoals about it, east of Nova Scotia. (5, 6) Two other ranges farther east. The Acadian is the longest of these Archaean ranges ; it is the chief eastern belt of the Archaean on the Atlantic border, and is strictly the Acadian pro- taxis. Its partial submergence is not in doubt ; for besides indications of this along the sea-bottom south of Nova Scotia, there is proof of subsidence of several hundred feet in the fiords of Maine and the coast; in the Bay of Fundy, in Massachusetts and Narragansett bays, and in Long Island Sound. The combination of the Acadian and Appalachian protaxes deter- mined the existence of the great " Middle Bay " of the Atlantic Coast (page 210), and in the region of their junction lies the bay of New York with the mouth of the Hudson. Thus the foundations were laid in Archaean time. On the Pacific border, northwestward in general trend. The chief Archaean ranges on the Pacific border are the following : (1) The Kocky Mountain protaxis, or the " backbone " of the mountains. It extends northward and westward nearly to 53 N., in the Peace Kiver region, and is represented be- yond in isolated areas. It bends eastward 250 miles south of 49 N., and then extends southward and westward through Colorado into New Mexico. The region of the bend, whence go off eastward and westward several of the large rivers of the continent, is the locality of the Yellowstone Park. Along the west side of the Wasatch Kange, near Salt Lake, the Archaean areas appear to be parts of a western spur of the protaxis, nearly in a line with the part of it in British America. To the westward are other nearly parallel Archaean ranges, in the Great Basin ; along the Sierra Nevada in California and in the Sierra Madre of western Mexico; and probably in the Coast and Island belts of British America. In addition, isolated areas occur east of the Kocky Mountain chain in the Black Hills of Dakota, the Iron Mountain region of Missouri, and in central Texas. Thus the oldest land areas marked out well the outlines of the continent. There is a landward bend in Pennsylvania of the Appalachian protaxis, like the landward bend of the Kocky Mountain protaxis, and the two bends are not much south in latitude of the southern end of the nucleal Archaean area of the continent; as if connected in origin with the absence farther south of outcropping Archaean. Archaean rocks are the prevailing rocks of the portions of Greenland free from its covering of ice, and they make a large part also of Baffin Land, on the opposite side of Baffin Bay. ARCHAEAN TIME. 445 SUBDIVISIONS OF THE ARCHAEAN TERRANES, AND THE ROCKS. Subdivisions. Two subdivisions have general acceptance : I. THE LAURENTIAN. Logan, Rep. GeoL Canada, for 1852-53; named from the Laurentide Mountains. II. THE HURONIAN ERA. Huronian of Logan and Murray, Rep. GeoL Can., for 1853-4-5, in the special report for 1854 ; Esquisse du GeoL du Can., 1855. " Huron Cupriferous Formation " of the north shore of Lake Huron, Rep. GeoL Can., for 1847-8. Part of Agnotozoic, Irving, 1887, the Keweenaw group of the Agnotozoic being referred beyond to the Paleozoic. Part of Algonkian, Walcott, 1889 ; a name proposed as a substitute for Agnotozoic, and so accepted by geologists. The subdivisions were based, according to Logan, on relations of uncon- formity in bedding between the Huronian and Laurentian terranes. The Huronian areas recognized were situated along the north shore of Lake Huron, and at points on the north and east shores of Lake Superior. Archaean rocks vary from massive crystalline kinds, like granite, syenyte, dioryte, and massive gneisses, to the thinnest of schists ; and include, also, limestone, quartzyte, and some uncrystalline sandstone and other fragmental beds, besides large beds of iron ore. The Laurentian division in the vicinity of the lakes was observed to comprise the more massive kinds ; and the Huronian, the thinner schists, as mica schist, chlorite schist, with quartzyte. With this distinction in view, the Huronian was made to include also an area south of Lake Superior extending from Marquette, Mich., westward, containing the large beds of iron ore of that region; and this conclusion has since been sustained by evidence proving their unconformability to the Archaean terranes beneath. But most other references of areas to the Huronian that have been made are reasonably questioned, because it is now known, as stated on page 458, that the distinction based on kinds of rocks is not a safe cri- terion of geological age. Among metamorphic Paleozoic rocks, massive, thick-bedded and thin-bedded schists are associated in the same formation ; and so it is, beyond doubt, in the Huronian, and even in the Laurentian. Still, the thinner schists of the Archaean are to a much larger extent Huronian than Laurentian ; and all the uncrystalline Archaean strata are Huronian. The beds of iron ore have so great thickness in some regions, that the Archaean has been called the Iron Age in the earth's history. The localities of Huronian described by Logan with special detail in the Canadian Geological Report of 1863 are as follows : (1) to the west of the Mississaga River, north of Lake Huron ; (2) to the eastward, in the vicinity of White Fish and Sturgeon rivers ; (3) near Lake Temiscaming, 15(Tmiles northeast of the last locality ; and a few miles from Michipicoten Island, north of Lake Superior. The iron-bearing rocks south of Lake Superior about Marquette and to the westward are referred to the same period on the colored map in the octavo Atlas accompanying the Report, published in 1863, after inves- tigations by Murray. 446 HISTORICAL GEOLOGY. Murray refers to the Huronian also diorytes, slates, quartzytes, and conglomerates, that occur in the peninsula of Avalon, southeastern Newfoundland, and describes, from the upper division, a fossil of uncertain relations which he names Aspidella Terra-novica, and also a worm burrow referred to the genus Arenicolites. The gneisses of the region he calls Laurentian. The structure and relations of the Huronian along the iron-bearing belt from Mar- quette to Penokee in Wisconsin (including the Penokee-Gogebic range, and the Menominee iron region) have been studied with care by Irving and Van Hise. Van Hise and Pumpelly have recognized a subdivision of the Huronian north and south of the lakes, on the ground of a stratigraphical break, into Upper and Lower Huronian. In most cases, kinds of rock have had chief importance in the subdivision of the Archaean. T. S. Hunt proposed the division of the Archaean (commencing below) into Laurentian, Norian, Arvonian (of Hicks), Huronian, Montalban, Taconian. The Montal- ban includes the White Mountain micaceous gneiss ; and the Taconian, the rocks of the Taconic series now known to be of Paleozoic age. C. H. Hitchcock in his Report on the geology of New Hampshire, adopts the subdivisions, beginning below : Laurentian, Mon- talban (or Atlantic, including granites, gneisses, etc.), Labradorian, and Huronian. A. C. Lawson, from his Canada studies about the Lake of the Woods, Rainy Lake, and else- where, has divided the terranes above the Laurentian into the Coutchiching (mica schists and gneisses) and Keewatin (thinner schists with conglomerates and some iron ore), and to the two united he has given the name Ontarian ; the term Huronian is not used. A. Winchell arranges the Marquette iron region below the true Huronian in a group called the Marquettian. The Laurentian Gneissic group underneath is made 88,000 feet thick. N. H. Winchell refers the original Huronian beds on the north shore of Lake Superior to the Lower Cambrian ; and makes the Archaean of Minnesota to include three divisions : (1) the Laurentian gneiss and related rocks ; (2) the Vermilion schists, partly hornblendic schists (equivalent to the Coutchiching of Lawson) ; (3) the Keewatin schists, which are iron-bearing. The Animikie beds, consisting of chlorite schist, slates, sandstones, and small beds of iron ore, having in general small dip, have been referred to the Huronian by Logan, Irving, and Van Hise, but to the Cambrian by Selwyn, Winchell, and others ; and Selwyn has announced the discovery in it of markings which, according to G. F. Matthew, are tracks much like the tracks of an animal found in the Middle Cambrian of St. John, New Brunswick. The Mesabi Range with its large beds of iron ore is made Cambrian by Winchell. The Archaean rocks of central Texas are divided by T. B. Comstock (1890) into the Burnetan and Fernandian, corresponding apparently to the Laurentian and Huronian. The latter section is described as containing large beds of magnetite. Overlying beds in which no fossils have been found he calls Eparchaean. M. E. Wads- worth has announced (1892) the following subdivisions of the Archaean in northern Michigan: (1) Cascade, (2) Republic, (3) Mesnard, (4) Holyoke, and (5) Negaunee formations ; 2 and 3 corresponding to the Lower Marquette, and 4 and 5 to the Upper. Van Hise, in 1893, proposed to restrict the term Laurentian to granite-gneisses a petrological distinction ; and gave to a supposed second division of the Archaean, the term Mareniscan, derived from the name of a township in Michigan. A bibliography of the American Archaean to 1884, with various notes, is contained in the "Azoic System," by Whitney and Wadsworth, pages 331-566 of vol. vii. of the Bull. Mus. Comp. Zool., Cambridge, 1886. A full bibliography, coming down to 1892, is pub- lished in the Report on the " Archaean and Algonkian," by C. R. Van Hise (1892), con- stituting Bulletin No. 86 of the U. 8. Geol. Survey. The latter work contains brief abstracts of the publications noticed, a full exposition of the views entertained, and the author's own conclusions at length. The distinguishing characteristics of the subdivisions proposed by Hunt, Lawson, and others are given in this Report with much fullness ; and all investigators of Archaean terranes should have a copy of it at hand. The subject is in an unsettled state, with wide divergences in opinion among investigators. ARCHAEAN TIME. 447 i Algonkian formation. The Algonkian formation (Agnotozoic of Irving) is made by its describers to include the Huronian of Logan, north and south of the lakes, and some of the so-called Huronian in other regions. Its rocks (1) comprise the thinner schists, semi- crystalline slates, quartzytes, and uncrystalline fragmental and shaly rocks ; and (2) they are of pre-Cambrian age. The supplanting of the older name, Huronian, by the newer is not sustained by any rules of nomenclature. It has been given a wider range by includ- ing under it the Keweenaw copper-bearing sandstone formation, which lies unconformably on the Huronian, and this change of limit was one reason for the change of name. T. B. Brooks first recognized the " Keweenawian " as a distinct system of rocks (1876) ; Irving called it Keweenawan. If Archaean instead of Paleozoic, it marks a Keweenawian period in the long Huronian era. The Keweenaw formation is without fossils, and hence is of uncertain age ; but its relations appear to be probably Paleozoic, as explained beyond. Some of the localities of Algonkian observed by Walcott are the following : (1) the tilted beds of quartzytes and siliceous slates at the base of the Wasatch series, lying con- formably beneath the Lower Cambrian ; and (2) strata beneath the Cambrian in the Eureka District and elsewhere in Nevada, where there is the same conformability. The beds are described as very thick and as affording no fossils ; but the conformability to the Cambrian suggests the query whether the beds are not lowest Cambrian. (3) At the base of the walls in Grand Canon of the Colorado, lying unconformably beneath Upper Cambrian beds, up- turned beds of sandstone, shale, and limestone, named by G. K. Gilbert, the Tonto group. The presence of fossils in some of the Tonto beds (including remains of a Stromatoporid, a Trilobite, and a Hyolithes, and a Discina-like shell) shows that part, at least, of the Tonto group is not Algonkian, and renders it probable that all is Paleozoic. (4) In central Texas, Llano County, beneath Upper Cambrian strata and over the Archaean, a formation which is called the Llano group. (5) Part of the Huronian of southeastern Newfoundland, described by Murray, which Walcott states is unconformable to the overlying Olenellus beds. (6) Below the Potsdam series in the Adirondacks. These are some of the local- ities of the so-called Algonkian formation. The facts respecting the Algonkian are reviewed hi Van Hise's Report of 1892, men- tioned above ; also briefly, on some localities, in Walcott' s Correlation of the Cambrian, U. S. Geol. Survey, Bulletin No. 81, 1891. Kinds of rocks. The more characteristic kinds of Archaean rocks are coarse granites ; thick-bedded gneisses, especially hornblendic varieties, sye- nytes, diorytes, and pyroxeuic varieties of these rocks ; the granite-like rock of the basalt type, called gabbro ; and each of these rocks under gneissic and thin-schistose varieties. Zircon-syenyte is rather common. There are also chrysolite rocks and chrysolitic varieties of some of the above kinds ; and with them, serpentine rocks, the serpentine being a result of the alteration of chrysolite or pyroxene and possibly of some other mineral containing magnesia. Crystalline limestone (usually dolomyte or magnesian limestone) is common in some regions ; and it often contains large crystals of apatite (calcium phosphate) and the pale yellow mineral, chondrodite (a fluorine- bearing magnesium silicate), supposed to be peculiar to the Archaean, besides many other minerals. There are also in the Laurentian series, but less abundantly, horn- blende schist, mica schist, hydromica (or sericite) schist, chlorite schist, and quartzyte. 448 HISTORICAL GEOLOGY. The massive rocks (whether Laurentian or Huronian) are generally igneous ; but, most probably, for reasons already stated, metamorphic igneous to a greater extent than deep-seated igneous. The granite and syenyte often contain great masses and long broken strips of schists, or constitute dike-like intrusions. Figures 495, 496 of portions of the rocks at Burntside Lake, in northeast Minnesota, are from A. Winchell's Field Studies in the Archuean Rocks of Minnesota. In these examples, granite and mica schist are the two rocks combined. In other figures, syenyte has the place of granite, and the schist is a hornblende schist. 496. Mica schist (the lined areas) and granite ; at m the two intimately mixed. Surface, 12 feet square. A. Winchell, '87. Mica schist and granite. Surface, 12 feet square. A. Winchell, '87. Often the massive rock contains only isolated blocks ; and from this con- dition there are all gradations to those represented in the figures. The rock fragments are not widely scattered, like those torn from the walls of a fissure by ascending lava, but often are still nearly in their original lines. In cases like those above described, the conclusion seems unavoidable that the extrusion of the melted rock followed closely on a general fracturing of the beds that are now schist, and that this could have happened only at an epoch of metamorphism, during the progress of a great upturning, when some one or more of the strata in a thick series of formations became fused by the excessive heat, and was forced up into fissures or spaces opened in the flexed and fractured unfused strata. The liquid did not make the fractures, but these being made, it flowed in and filled all crevices. In other places, described by Winchell, and especially in the vicinity of Saganaga Lake, the granites and the associated gneiss contain rounded peb- bles every rod or two, two to six inches in diameter ; and at one locality the pebbles, though not in contact, were " in such abundance as to constitute a ARCHAEAN TIME. 449 real conglomerate," giving evidence of "attrition," "fragmental accumula- tion," and subsequent metamorphism. The rounded stones were four to five inches through, and consisted of crystalline augitic and other rocks. In the recognized Huronian areas on the north shore of Lake Huron, and in the Penokee-Marquette belt, south of Lake Superior, extending from Wisconsin into northern Michigan, the rocks are quartzyte, siliceous schist, sandstones, conglomerates, micaceous and chloritic slates, chloritic greenstone, dioryte ; and in Wisconsin there is a cherty limestone at the base, and carbonaceous as well as graphitic shales above. A common feature of Archaean rocks, or at least of their veins, is the frequent occurrence of minerals containing rare elements, as niobium, tantalum, lanthanum, thorium, yttrium, zirconium, caesium, rubidium, and others. The following minerals are common in Archsean rocks, or their veins: nephelite (elseolite), cancrinite, sodalite, spinel, chryso- beryl, danburite, amblygonite, spodumene, petalite, microlite, gadolinite, cryolite, besides others. But garnet, mica, andalusite, cyanite, staurolite, are less common than in later crystalline rocks. Chondrodite is usually, if not always, Archsean. In the Kent-Cornwall ridge, west of Kent, Conn., and in the high land east of Tyringham, Lee, and Pittsfield, Mass., occur chondroditic limestones, like that of Sussex County, N.J., and at a locality east of South Lee, near the junction of the Archaean rocks with the Cambrian quartzyte, masses of chondrodite occur as large as the fist. One of the most characteristic features of the Archsean is the occurrence of great beds of valuable iron ore, some of them 100 to 400 feet thick. They are found of great thickness in Canada, northern and southeastern New York, northern New Jersey, and the region south through Virginia to Georgia; in the Penokee-Marquette belt, south of Lake Superior; the Missouri Iron Mountain region; also in Utah, Wyoming, Colorado, New Mexico, and Arizona, and elsewhere. The ores are usually magnetite, hematite, and titanic iron, of bright, lustrous kinds; and in one region, in Sussex County, N.J., it is a zinc- manganese iron ore, called franklinite, mixed with disseminated zinc oxide 497. 498. 499. Northern Michigan, Whitney. Essex County, N.Y. Essex County, N.Y. Kmmons. Emmons. and zinc silicate. But, besides these kinds, there is also iron carbonate or siderite. Figs. 497 to 499 show some of the positions of the ore-beds in metamorphic schists, the black beds i being the ore-beds, and the ore magnetite or hematite. In Fig. 497, the ore-beds (of northern Michigan) are between beds of DANA'S MANUAL 29 450 HISTORICAL GEOLOGY. chlorite schist and dioryte, and have jaspery bands. In 497, 499, from Essex County, N.Y., the associated rock is gneiss, and the ore-bed is interlaminated with quartz. At one Essex County mine, the ore-bed is 150 feet thick ; at the Cranberry mine, on the borders of North Carolina and Tennessee, 400 feet. Grains of calcium phosphate (apatite) are often disseminated through the ore. Iron carbonate is associated with the oxides south of Lake Superior. It occurs only sparingly to the eastward in Michigan, south of Lake Superior, at the Marquette mine, but more abundantly to the westward in Wisconsin. The metamorphism of the beds, correspondingly, is least to the westward. The carbonate is the ore originally laid down, and the hematite and magne- tite are results of metamorphic change, in which the carbonic acid was ex- pelled. In eastern Canada and along the Archaean pro taxis, southward through New York, New Jersey, and beyond, the carbonate is wholly absent, the iron ores being magnetite, hematite, or titanic iron. Moreover, the thickness of the ore-beds is far greater and the metamorphism of the region is of higher grade, thick-bedded, massive, and schistose, crystalline rocks prevailing. Notwithstanding these differences, the eastern iron-bearing series may be Huronian, and unconformable to adjoining Laurentian, but the evidence of this has not been obtained. The same belts have their thick beds of crystalline limestone, often chondroditic, and in this respect rocks of the Appalachian protaxis differ from those of the Lake Superior region. The course of the Appalachian chain was the region in later time of thick sedimentary deposits, great upturnings, intense metamorphism, while, cotemporaneously, little change was in progress over the Mississippi Valley ; and it may be that the same kind of difference distinguished the two regions in Archaean time. STRUCTURE, THICKNESS, AND ORIGIN OF THE ROCKS. As is implied in the preceding descriptions, part of the rocks are massive, as granite, syenyte, dioryte, gabbro ; and a large part are schistose and dis- tinctly stratified ; and into the schistose the massive often graduate. The alternations of ore-beds with schists, quartzyte, limestones, in sections like those figured above, are evidence of strati- fication, and, therefore, of the succes- sive formation of the beds, whether now crystalline or not. The quartzytes are old sandstones; the limestones deposited beds interstratified limestone, St. Lawrence of ii mes t0ne, either of organic or chemical County, N.Y. Kmmons. origin ; and the schists are fragmental beds in a metamorphic condition. In Fig. 500 a stratum of limestone, I, is overlaid by strata of gneiss, a, a, and steatyte, b. Such sections could be multiplied indefinitely. The following, by Logan, Fig. 501, which is partly ideal, but not untrue, represents white granular or crystalline limestone, a, many times folded and interstratified with gneiss and quartz rock, b ; and the limestone has been traced over the same region (Grenville and the adjacent country, Canada), in the linear and curving bands of a series of great ARC H^E AN TIME. 451 flexures. The facts prove that the beds were laid down horizontally over large continental areas, and that denudation in Archaean time, making sediment, was carried on by the ocean along its margins or over partly emerged rocks, and by streams over the land, as it is now. The streams were short in that time of contracted lands, yet well supplied with water 501. under the hot climate. The thickness of the rocks indicates that the amount of deposition and rock-making was enormous. The waters of the small streams and of the ocean owed much of their efficiency to the carbonic acid they contained, this gas being everywhere in excess. Moreover, under these conditions, the formation of beds of iron ore along the shallow margins of the sea and in the shallow waters of the land would have been necessarily one of the great features of the later part of Archaean time ; for the decom- posing iron-bearing rocks would have readily yielded their iron to the attack- ing carbonic acid. Moreover, organic deposits of silica may have accompanied the ore-beds in the basin. A thickness of 30,000, 50,000, and 80,000 feet has been attributed to the formations piled up in one series or region. If this means 50,000 feet or more in a single geosyn- clinal area before an upturning, the estimate is to be doubted, for the difficulties of correct measurement of flexed rocks are great. In most cases the facts as to the faults and flexures present cannot be ascertained. A thickness of 50,000 feet of uncrystalline sediments in a geosyncline, during even the later part of Archaean time, militates against all calculations as to the Archaean rate of increase downward in the earth's temperature ; for if the rate were 1 F. for 10 feet of depth, as Thomson has calculated, the bottom of such a geosyncline would have had a temperature of 5000 F. ; or if 1 F. for 25 feet, it would still have had a temperature sufficient nearly for the fusion of basalt. ARCHAEAN MOUNTAIN-MAKING. The stratified rocks of the Archaean are almost everywhere upturned, and generally at high angles, the dip usually being between 30 and 90. Only portions of the Huronian are nearly horizontal. Moreover, as repre- sented in Fig. 501, they are commonly in flexures, from a few yards to miles in span. Such flexures, whenever they occur, are evidence that great upturn- ings had taken place of the Appalachian kind. The crystallization of the rocks, or their metamorphisrn, was an accompanying result. The rocks of the earliest Paleozoic often lie over them nearly or quite horizontally, as illustrated in the accompanying figure (Fig. 502) from Logan, representing a section from the northern or Canadian side of the Adirondacks. Upon the flexed Archaean rocks lie (2) the Potsdam sandstone of the Cambrian, 452 HISTORICAL GEOLOGY. and (3, 4a, 46) overlying Lower Silurian strata. Such sections of Cambrian strata over the upturned Archaean are proof that the mountain-making in the region preceded the Cambrian era. It is probable that the Adirondacks were made at the close of Archaean time. They were, from the first, great mountains, for the highest of the summits, Mount Marcy, now stands 5000 feet above the Cambrian seashore, or the lowest Cambrian beds, and this is the height remaining after long ages of denudation. For the original height, 8000 feet above the Cambrian tide-level can hardly be too high an estimate. 502. From the south side of the St. Lawrence iti Canada, between Cascade Point and St. Louis Rapids: 1, gneiss ; 2, overlying Potadam sandstone; 3, calciferous sand-rock; 4a, Trenton limestone; 46, Hudson slates. Logan. The fusion of beds by the heat in the lower and hotter part of the geo- syncline would have made, by the escape of the liquid rock alone, fissures, veins of igneous rock in the metamorphic region, and also inclosures of the broken schists of the upper and less heated part of the mass (page 448). Such igneous eruptions are of the same age as the metamorphism. How many epochs of upturning occurred in the course of Archaean time is unknown. In the vicinity of lakes Huron and Superior (and probably also farther east) there was one at the close of the Laurentian period. Over the Archaean area of New Jersey, and of Orange and Putnam counties in New York, there are several long belts of Cambro- Silurian rocks, occupying what were originally valleys of Archaean time, having the northeastward trend of the rocks. They are fossiliferous in New Jersey, and partly metamorphic in Putnam County, N.Y., north of Peekskill. They once spread more widely over the Archaean Highlands, and, perhaps, covered the whole when the Coal-measures were finished, as considered probable by J. P. Lesley. The upturning the beds have undergone took place in spite of resistance to fracture or compression in the underlying Archaean rocks. SUBSEQUENT ALTERATIONS OP ARCHAEAN ROCKS. Archaean rocks have in many places undergone changes in their minerals. They were made at higher temperatures, under greater atmospheric pressures, and with slower rates of cooling, than ordinarily obtain now at the earth's surface ; and these changed conditions, and especially those due to heat from orographic movements, have occasioned alterations in some constituents. Many Archaean rocks that are now hornblendic were originally pyroxenic. Since other pyroxene rocks have remained unchanged, some circumstances must have intervened to commence the alteration ; and it may be that it was a heating up of the rocks to 1000 F., through fracturings, faultings, and crushings attending earth-movements or mountain- making. Besides the above-mentioned change, chrysolite, pyroxene, hornblende, and ARCHAEAN TIME. 453 other minerals have been converted into serpentine ; pyroxene into rensselaerite, a variety of talc ; nephelite into gieseckite ; spinel to hydrotalcite. Another change is that of mag- netite to hematite ; for the great beds of hematite sometimes contain octahedral crystals now consisting of hematite, which, when formed, were octahedrons of magnetite. In the ore-beds of the Huronian the layers of ore, jasper, or other materials are often much broken and displaced. The grains of apatite are sometimes more abundant along one side of an ore- bed than the other, or have some reference to the depressions in which the ore lies (Browne, 1889). The dioryte underlying the ore-bed has been altered in many places to a soft clayey material, feeling soapy, resembling the fluccan of a vein. The underlying rock is sometimes that of a dike, but whether consisting of dioryte or diabase, it is, in general, probably, as Hunt held, a rock of sedimentary origin. As dioryte and diabase were very abundant rocks, sediments made from them would have then been com- mon. The broken and otherwise displaced condition of the ore-beds, and the rearrange- ments of the ore in any depressions that were made, would have been a consequence, under the results of wider disturbance, of the important fact that in the change of the carbonate to hematite or magnetite, there is a reduction in the former of one third in bulk, and in that of limonite to the same ores, a reduction of one half or more, so that large spaces would have been opened, favoring large displacements. The subsequent changes, alluded to above, probably occurred at some later epoch of regional disturbance, in the course of which movement was produced along the plane of the ore-bed. Under the action of the heat from friction siliceous and other solutions would have been formed anew and mineral changes have taken place. LIFE OF ARCHAEAN TIME. Although fossils, according to present knowledge, are absent from Archaean rocks, or are of questionable character, the existence during the later part of the Archaean of aquatic life in its simplest forms is rendered almost certain by the fact that the temperature of the waters was favorable to it, and by the occurrence among the stratified rocks of beds of limestone ; by the abundance in many limestones, and other rocks, of graphite, which constitutes 20 per cent of some layers in Canada ; and the presence in the Huronian of carbonaceous shales or slates containing 40 per cent of carbonaceous mate- rials. The life belonged to that division of Archaean time which is desig- nated, on page 441, the Archaeozoic aeon ; and the Huronian rocks represent the latter part of this aeon, if not the whole of it. PLANTS. Graphite crystallized carbon has been made in many later rocks by the alteration of coal-beds ; as at Worcester, in Massachusetts, in Rhode Island, at St. John in New Brunswick, where ferns among the coal- plants have been found in the state of graphite, in Ayrshire, Scotland, and in Bavaria. Even anthracite has been observed in the Archaean rocks of Arendal, Norway. Dawson has remarked that it is scarcely an exaggeration to maintain that the quantity of carbon, in the form of graphite, in the Archaean rocks of Canada is equal to that in similar areas of the Carbonifer- ous system. It is reasonable to conclude, therefore, that although graphite may also be produced by heat, that of the Archaean was largely of organic origin, like that of later rocks. The metamorphism of shales containing carbonaceous materials derived from vegetable, if not also animal, tissues, 454 HISTORICAL GEOLOGY. has converted the carbon into graphite. The little-altered Huronian beds of Wisconsin still contain much carbonaceous material, as remarked by Brooks and Chamberlin. The former stated, in 1876, that " the considerable amount of carbon distributed through the Huronian indicated much organic life, and leads to the hope that" those imperfect fucoidal impressions reported by Julien, in the second volume of the Report on the Geology of Michigan, may not prove delusive. The earliest plants were, beyond doubt, Algae, water species, which grow, like most plants, by taking carbon from carbonic acid ; and after these, the microscopic Fungi related to the Bacteria (Microbes), which take their car- bon for growth chiefly from organic products ; for these minute plants are essential to the process of decay of organic matters and also to the produc- tion of many mineral changes, as already explained. The chert of the limestone in the Penokee belt of Huronian, and the jasper associated with the iron ore of the belt, consist partly of opal-silica, and are probably from silica-secreting Algae (Irving, Van Hise). It is proba- ble that plants related to those that are now secreting limestone and silica in the hot waters of Yellowstone Park, below temperatures of 185, were already doing geological work in the making of limestones and silica deposits during the later Archaean. One species of supposed " seaweed" has been named Archceophyton Newberrianum by N. L. Britton. The specimen, from a New Jersey crystalline limestone, consists of graphite arranged in narrow parallel stripes, with a regularity that suggests organic origin ; but the arrangement may well be an effect of the pressure attending metamor- phism. ANIMALS. With regard to animal life, the supposed fossil, Eozoon Canadense of Dawson, is regarded by some as proof of the existence of Rhiz- opods (Foraminifers), while others believe it to be of mineral origin. It occurs in coral-like masses which are sometimes several feet in diameter. Fig. 503 represents, natural size, a section of a specimen from Grenville, Canada. The white bands are the calcareous layers supposed to have been secreted by a layer of the Rhizopods, while the dark bands correspond in position to the layer of Rhizopods, and are made up of mineral mate- rial (serpentine generally, sometimes pyroxene, loganite, etc.) that, after the death of the animals, filled the cells. Dilute muriatic acid removes the lime- stone, and opens the rest to examination. Localities occur in the third or Grenville stratum of limestone near Grenville, and in the Petite Nation Seignory ; also in Burgess (where the calcareous part is dolomite), and at the Grand Calumet, in a limestone whose place in the series is not determined ; and at Tudor in Hastings County. Eozoon has also been reported from Archaean rocks in Bavaria 503. Eozoon Canadense. Dawson. ARCHAEAN TIME. 455 and named E. Bavaricwn; also from Saxony, Bohemia, Hungary, and Pargas in Finland. The specimens of Eozoon were first supposed to be Stromatopora corals (Logan's Hep. Geol. Can., 1863, page 49), and afterward announced as Rhizopod in structure by Dawson ; and this conclusion has since been sustained by W. D. Carpenter and others. But Eozoon specimens have also been examined microscopically by good observers, among them King and Rowney, and Mobius, who have not found the supposed foraminiferal characters. Quite recently, in 1891, the Tudor specimens were examined by J. W. Gregory with this conclusion. Doubts are excited also by the close resemblance in structure to specimens that are of mineral origin ; by the unequal thickness of the calcareous layers and the interstices ; and by the fact that serpentine of later formations has afforded similar forms. It is objected to on the ground that this mineral is often minutely interlaminated with fibrous serpentine or some other mineral, showing that the soft amorphous material, as it solidified, sometimes contracted and divided into thin laminae, leaving spaces between to receive depositions of any kind ; in the Eozoon the infiltrating material was usually calcareous. Notwithstanding the imperfection of the evidence, the existence of Rhizopods and other Protozoans before the close of Archaean time is gen- erally believed. The calcium phosphate (apatite) of the rocks, which is common in some limestones, is also supposed to be of organic origin, because a constituent of organic tissues and of some shells. Its abundance also in the iron ores favors this view, inasmuch as the beds of ore are believed to be marsh pro- ductions. But the phosphate is distributed in grains through many igneous and other crystalline rocks, and the evidence may only prove that it was present in solution in the sea-waters of the era. Above the grade of Protozoans, the type which is most likely to have existed in the later Archaean is that of Kotifers ; for there is good reason for believing, as stated on page 423, that from this group passed off independent successional lines of species to Worms, Limuloids, Crustaceans, and terres- trial Arthropods, and probably also to Bryozoans, Brachiopods, and perhaps other tribes. ECONOMICAL PRODUCTS. The chief economical products of the Archaean terranes are : (1) Gold, platinum, diamond ; (2) Iron ores ; (3) Copper, and other ores ; (4) Corun- dum or emery ; (5) Graphite ; (6) Architectural materials, especially granite and marble ; (7) Apatite or calcium phosphate for fertilizing purposes ; (8) Feldspar for porcelain-making ; (9) Mica for the doors of lanterns, stoves, etc., and various other uses ; (10) Zircon and monazite. The iron ores are among the most valuable. They sometimes contain too much titanium ; and occasionally the proportion of disseminated grains of apatite affects their value. This mineral may be distinguished by its green- ish or grayish color and by its being soft enough to be scratched by the point of a knife-blade. The American corundum (A1 2 3 ) comes mostly from North Carolina and Georgia. A mass weighing 400 tons was formerly obtained in the rocks of Chester County, Pennsylvania. The mineral is ground up and used for emery, it being the same compound as emery, but in a purer form. 456 HISTORICAL GEOLOGY. ARCK&AN TIME IN OTHER COUNTRIES. South America has its northern region of Archaean rocks between the equator and the Orinoco, which would probably have a much larger super- ficial area but for the great alluvial and Tertiary area of the Amazon and other rivers, which bound it for 150 miles on the north and two to three times this width on the west. Archaean ranges also occur in Brazil, and in different parts of the chains of the Andes. In the continent of Europe the great Archaean region is the Scandinavian, or that covering the most of Sweden, Norway, Lapland, and Finland. The rocks also occupy a large part of the northern half of Scotland and the Outer Hebrides; portions of western Ireland, at Donegal and Gal way, and of eastern, in Wicklow ; at St. David's, in southwest Wales ; in Anglesey, off northwest Wales ; in western England, in the Malvern Hills ; and probably on the south coast of Devon and Cornwall. They also cover areas in Saxony, Bavaria, and Bohemia; in Brittany, Vosges, and the Central Plateau of France. Crystalline rocks cover, according to Blanford (1879), very large areas in India. " More than half of Peninsular India is taken up by the eastern gneissic series." They extend, with scarcely an exception, from Cape Comorin to Colgong on the Ganges, 1400 miles. The mean breadth of the area is 350 miles. There are also in the peninsula a northwestern area, the Arvali ; and, to the north of the Vindhyan plateau, the Bundel- khand area. But it is not certain that all are Archaean. Besides these, there are also large areas of semi-metamorphic rocks. The main Himalayan range has a gneissic or granitic axis, but the limits are not yet laid down ; and in the Zanskar range, its continuation to the northwest, there is a center of gneiss. But the precise relations of these and other gneissic ridges to the later formations has not been ascertained. The rocks of Scotland, Norway, Sweden, and other Archaean regions are much like those of North America in general constitution, and in the range of the associated minerals ; and in Scandinavia there are great iron ore beds. The massive gneisses of the Hebrides and northern Scotland were called the Lewisian group by Murchison (1858), after the island of Lewis in the Outer Hebrides. Like the massive and the thick-bedded or foliated rocks, which contain the iron ore beds of Scandinavia, they have been pronounced on petrological grounds to be of igneous origin. But, for reasons already stated, they are in all probability, wherever igneous, metamorphic-igneous, or the result of fusion attending metamorphic work. The foliation of the gneisses and other rocks represents, in general, on this view, true bedding. The iron ore beds are the best of evidence of metamorphism. The crystal- line rocks east of the " Great glen " in Scotland include thin schists and quartzyte with gneiss, and have been called the Grampian group by H. Hicks, and later the Dalradian group by Geikie ; it is supposed to be younger than the Lewisian. ARCHAEAN TIME. 457 The crystalline rocks of St. Davids, in Wales, have been described by Dr. Hicks as of three periods : (1) the Dimetian; (2) the Arvonian; and (3) the Pebidian. Geikie concluded, after an examination of the region, that the Dimetian rocks are intrusive granite ; the Arvonian, " quartz-porphyries " connected with the granite; and that the Pebidian rocks are tufas and diabases belonging to the lowest Cambrian. Dr. Hicks's view that the St. Davids rocks are partly Archaean is favored by the presence in the vicinity of fossiliferous Cambrian. It is now adopted by Geikie. In the Torridon district, northwestern Scotland, a thick formation of red- dish and brownish sandstones, wholly uncrystalline in texture, but upturned to a high angle, lies unconformably both upon Archaean gneisses and under- neath strata of Lower or Olenellus Cambrian. The reported thickness is 4000 to 8000 feet. As they are unfossiliferous, it remains doubtful whether the Torridon sandstone, or " Torridonian group,' 7 should be referred to the later Archaean, or to the earliest Paleozoic. Murchison referred them to the Cambrian. OBSERVATIONS ON THE ARCH^AN. 1. Relations of the North American Archaean areas to the continent. The position and form of the nucleal Archaean of the continent, and of the parallel ranges on either side, reaching out to the oceans, prove that the continent was not only outlined, but also marked off as regards its grander features in Archaean time. This is established also by the great thickness of meta- morphic rocks ; for rocks of sedimentary or detrital origin are not made except where there are emerged, or nearly emerged, rocks to be a source of material; and even a slight submergence makes the amount of decay, and of detritus produced, small. Further, the existence of the continents, emerged or at shallow depths, is evidence, as explained on page 380, that the oceanic basin also was denned by the close of the Archaean, and had nearly its present mean depth of 12,000 feet. The facts thus prove that the scheme of progress, even to minor details, dates from the beginning. In the very inception of the continent, not only was its general topography foreshadowed, but its main mountain chains appear to have been begun, and its great intermediate basins to have been defined. The evolution of the grand structure lines of the continent was hence early commenced, and the system thus initiated was the system to the end. Tracing out the development of the American continent, from these Archaean beginnings, is one of the main purposes of geological history. 2. Correlation of Archaean subdivisions. Names of Archaean subdivisions are multiplying over the world wherever Archaean rocks are studied. The uncrystalline terranes are safely put at the top of the series in the particular region where they occur ; but, as already remarked, they may be the equiva- lents of crystalline kinds in another more mountainous region. 458 HISTORICAL GEOLOGY. With the more crystalline terranes correlation is extremely difficult. This is owing to the absence of fossils ; to the uncertain value of the cri- terion based on kinds of rocks ; and to the fact that no subdivision admits of being traced to any great distance, except the kind which depends on unconformity in bedding. Since this kind of unconformity is a consequence of an orographic upturning, and mountain ranges have usually great length, it will theoretically exist for long distances. Subdivisions based on other kinds of unconformity, and on the characters of the rocks, are the most common, and are necessarily of only local value. The study of a region with reference to unconformity in bedding involves a complete investigation of the positions of the planes of bedding, or foliation, wherever the rocks are exposed to view. The beds of iron ore and the graphite-bearing schists of Wisconsin are proved to belong to the later part of Archaean time the Huronian ; and this is probably true for the associated Archaean beds and schists, whether massive, gneissic, or thin schists, and hence beds of iron ore are a great help in correlation. The beds of limestones may yet be found to give aid in the same direction. The study of the Archaean rocks has difficulties, but not so great as are implied in the term "Basement Complex," sometimes used for the more crystalline kinds, an expression that sounds like a wail of despair on the part of those that use it. 3. Source of the material of later fragmental rocks. The Archaean rocks, and rocks made from them, are the main source of the material of sub- sequent non-calcareous fragmental rocks. Volcanic eruptions have added a little to the supply ; chemical depositions also a little ; and the siliceous secretions of the lowest orders of plants and animals have contributed silica to some extent; but all these sources are small compared with those of the Archaean terranes. Even the limestones have derived much of their material from the same source, through the dissolving waters. The areas were well distributed over the continent for supplying, through the help of the ocean, mud, sand, and gravel for the deposits that were in progress as the next era opened better even than is now apparent, since many once exposed are now covered, especially along the sea-borders, where the later rocks have often great thickness. And their contributions have continued ever since to be used in rock-making, both directly and through the strata which had been made from them. 4. The first of living species. Science has no explanation of the origin of Life. The living organism, instead of being a product of physical or chemical forces, controls these forces for its higher forms, functions, and purposes. Its introduction was the grandest event in the world's early history. It is probable that the first species were of the simplest kinds ; that the animals were devoid of special organs of sense, and of motion, excepting AECH^AN TIME. 459 short, hair-like processes ; and of nutrition, beyond at the best a cavity for digestion. But the principles inaugurated were those fundamental to all life. Some of them are as follows : 1. The subordination of chemical and physical forces to the control of living conditions. 2. Germ-development, by which, from a germ-cell, a structure of various functions becomes evolved, and is carried to an adult or germ-producing stage, when new germs are produced for another cycle of development. 3. Death of the adult, a fundamental stage in the cycle, the institution of life involving the introduction of death. 4. In the case of animal life, dependence on living food for growth a principle that pervades the animal kingdom from its lowest species to Man. 5. As a consequence of growth and germ-development in animals, the initiation of two diverse moral forces, which later became a power in the world: (a) the affiliating influence, arising out of the relation of parent to progeny; (6) the antagonistic, self-asserting influence, arising from the necessity of food. Each element had reinforcements from other appe- tites or conditions in animal life. II. PALEOZOIC TIME. SUBDIVISIONS. The higher subdivisions of Paleozoic time are as follows : 1. Eopaleozoic Section. I. CAMBRIAN ERA. II. LOWER SILURIAN ERA. 2. Neopaleozoic Section. I. UPPER SILURIAN ERA. II. DEVONIAN ERA. III. CARBONIC ERA. Paleozoic time is naturally divided into two sections at the break between the Lower and Upper Silurian. This boundary line is marked in the history by an epoch of mountain-making in eastern North America and western Europe, and by a somewhat abrupt transition in the animal life of the seas. These sections are here named by using prefixes to the term paleozoic derived from the Greek T)W?, dawn, and veos, new. The first of these sections, the Eopaleozoic, was characterized by the fact of almost universal seas over the continental area, and of universal marine life, and also by the more specific Paleozoic fact, that marine Invertebrates, or the species of the inferior division of the Animal Kingdom, were dis- played under nearly all their grander types before the close of this section of Paleozoic time ; and also that the highest division of the Animal King- dom, Vertebrates, was represented by species of the inferior type of Fishes. The second of the sections, the Neopaleozoic, was characterized by the gradually increasing extent of v dry land over the continental area, and the covering of the emerged surface with land plants, and finally with great forests ; and also by the multiplication of terrestrial species of animal life among Invertebrates, and finally among Vertebrates. With the progress of the era, Cryptogams, plants of the lower division of the Vegetable Kingdom, reached their culmination in grade, size, and diversity of kinds; and the superior division of the Vegetable Kingdom, Phaenogams, was represented by species of the inferior type of Gymnosperms. The Eopaleozoic section was, biologically, following Agassiz's method of designation, the time of the E-eign of the Invertebrates, and prominently of Trilobites ; the Neopaleozoic, in its Upper Silurian and Devonian eras, the time of the Eeign of Fishes,, and in the Carbonic era, that of the Keign of Amphibians. The first real progress in correlating the Paleozoic rocks of North America and Europe was made through the labors of the geologists of the survey of the State of New York, and those of Murchison, Sedgwick, De Verneuil, and others abroad. But, in this 460 PALEOZOIC TIME. 461 work, American geology owes much to De Verneuil for liis "note" of 64 pages in the Bulletin of the Societe Geologique de France, iv., 1847, " On the Parallelism of the Paleo- zoic Formations of North America with those of Europe," which is followed by a list of the species of fossils common to the two continents, and of the rocks in which they occur, with critical remarks respecting each species; and to the paper of D. Sharpe, " On the Fossil Mollusks from the Paleozoic Formations of the United States," contained in the collections of C. Lyell, Q. J. G. Soc., 1848. AREAS OF GEOLOGICAL PROGRESS. Archaean geography, as has been explained, largely determined the areas of later geological progress, and the character of continental geography through all the ages. The prominent points in North American geography, besides the fundamental one of the Archaean nucleus, are the denning of the two great Archaean chains of islands or island ridges, the Appalachian pro- taxis on the east, the Rocky Mountain protaxis on the west (page 24). By this means a vast Interior Continental Sea was divided off from an Atlantic border region on the east, and a Pacific border region on the west, the former (reckoning to the 100-f athom line, or the steep border of the Atlantic depres- sion) averaging 300 miles in width, but becoming three times this in the latitude of Newfoundland ; the latter, 1000 miles in mean width. Besides this, the shorter Archaean ranges of the Atlantic border region to the north (see the map) divide the surface into a parallel series of broad channels or troughs, all of which open northward into the St. Lawrence valley region. 1. The Champlain and St. Lawrence channel : between the northern part of the protaxis and the Archaean lands ; on the west stand the Adirondacks, and on the north the Canada Archaean. 2. The Connecticut valley channel, or trough, along the CoDnecticut valley, and reaching Long Island Sound at New Haven Bay, Conn. 3. The Maine-Worcester channel : covering Maine and western New Bruns- wick and extending down to Worcester, Mass. ; apparently fading out south- ward. The fiord of the Thames Eiver, from Norwich to New London, Conn., lies in its course. 4. The Acadian channel : extending from St. Lawrence Bay and western Newfoundland over eastern New Brunswick and much of Nova Scotia, with the Bay of Fundy between, as the remains of this part of the depression ; thence southeastward along and off the coast regions of Maine to Massachu- setts Bay, and over eastern Massachusetts to Narragansett Bay, on the Atlantic border. 5. The Exploits River channel of central Newfoundland, and two others to the eastward. The importance of these channels, or troughs, becomes strongly pronounced in the course of Paleozoic history. Over the Pacific border region the areas are less plainly indicated than 462 HISTORICAL GEOLOGY. over the Atlantic, because the western half of the continent is so generally covered with Mesozoic and Cenozoic rocks. Paleozoic rocks are the prevailing kinds exposed to view over the eastern half of the North American continent, excepting along the borders of the Mex- ican Gulf and of the Atlantic south of New York. The older formations of the series, as the map on page 412 illustrates, lie near the Archaean area, not far north or south of the northern boundary of the United States ; and the newer formations outcrop in succession southward, the Carboniferous covering much of Pennsylvania and other States. Fig. 504 is an ideal section of the Paleozoic rocks of New York, along a line running southwestward from the Archaean across the state to the coal 504. Carbonic. Devonian. Upper Silurian. Lower Sil. Camb. region of Pennsylvania. It shows the relative positions of the successive strata, bringing out to view the fact that the areas over the region are only the outcrops of the successive formations. This is all the section is intended to teach ; for the uniformity of dip and its amount are very much exagger- ated, and the relative thickness is disregarded. Along the Appalachians the older Paleozoic rocks occur in long belts parallel with the axis of the range, because of the great upturning of the formations that took place at the close of the Carboniferous, when the mountains were made. EOPALEOZOIC SECTION. CAMBRIAN ERA. STN. Cambrian, Sedgwick, Eep. Brit. Assoc., 1835. Cambrian (Murchison's Lower and Upper Silurian being made higher divisions of the Paleozoic series), Sedgwick, Q. J. G. Soc., 1846, page 130. Cambrian (Murchison's Lower Silurian being included under it), Sedgwick, Q. J. G. Soc., 1852, page 147. Lower part of Lower Silurian, Mur- chison, Q. J. G. Soc., 1852, page 173; D'Orbigny, GeoL, 1851. Cambrian, Lyell, Elements GeoL, 2d ed., 1841 ; 5th ed., 1855; Geikie, Text-book of GeoL, 1879, 1885; Lapparent, Tr. de GeoL, 1883; Seeley and Etheridge, Man. GeoL, 1885 ; Prestwich, GeoL, 1886 ; E. Kayser, Lehrb. geol. Form., 1891. Primordial or lower division of the Silurian System, Stage C, Barrande, Syst. Silurien de Boheme, 1852. Cambrian or Primordial, a subdivision of the Lower Silurian, this GeoL, 1874, 1880; C. Vogt, GeoL, 2d ed., 1866; Credner, GeoL, 6th ed., 1887. PALEOZOIC TIME CAMBRIAN. 463 Potsdam Sandstone, New York Geol. Survey, 1842. Primal Sandstone, H. D. and W. B. Kogers. Upper Taconic, fossiliferous slates of Georgia, etc., E. Emmons, 1844, 1846 (not in the Taconic System of 1842) . History of the terms Cambrian and Silurian. The terms Cambrian and Silurian recognize the united labors of Murchison and Sedgwick in the first careful study, in Great Britain, of the older fossiliferous rocks of Paleozoic time. The two eminent English geologists worked together in some of their earlier investigations. The memoirs of that period, "Communications on Arran and the north of Scotland, including Caithness (1828) and the Moray Firth, others on Gosau and the eastern Alps (1829-1831) ; and still later, in 1837, a great memoir on the Paleozoic strata of Devonshire and Cornwall, and another on the coeval rocks of Belgium and north Germany, show the labors of these intimate friends combined in the happiest way the broad generalizations in which the Cambridge professor delighted, well supported by the indefatigable industry of his zealous companion." l In 1831, they were both at work " without concert " on the borders of Wales, Murchison chiefly on the English side and in southern Wales, and Sedgwick beyond the bound- ary in north Wales. Sedgwick had earlier investigated somewhat similar rocks in the Cumbrian Mountains. By 1834, Murchison had laid down his grand divisions of Ludlow, Wenlock, Caradoc, and Llandeilo, and had referred the first two of them, on the ground of the wide difference in fossils, to the Upper Silurian, and the latter two to the Lower Silurian. In 1835, the terms Cambrian and Silurian appear together in a combined paper presented by the two authors to the first meeting of the British Association. Silurian had been announced by Murchison nearly two months before in the July number of the Philosophical Magazine. In 1838, each put forth more fully his results : Sedgwick, in a paper read before the Geological Society, giving the distribution and character of the rocks, with but little notice of the char- acteristic fossils ; but Murchison, before the close of the year, in a quarto volume of 800 pages copiously illustrated with figures of fossils and geologi- cal sections, entitled the "Silurian System." Murchison's work and his names of subdivisions came into immediate use in all countries, and were recognized in all geological treatises. Gradually it came to light that the Lower Silurian of Murchison com- prised rocks and fossils of the age of the Upper Cambrian; and also that the fossils from beds of still lower level differ little in general type from those of the Lower Silurian. Thus geologists, with Murchison's book in hand, were led to use the term Lower Silurian for the fossiliferous Cambrian. No fall account of Sedgwick's Cambrian fossils was published before 1852 to 1855, and not even lists of species before 1843. In 1846 Sedgwick made his first protest against the absorption of the Cambrian by the Lower Silurian of Murchison ; and in 1852 the controversy, thus begun, ended in his claiming the whole of the Lower Silurian as Upper 1 Professor John Phillips, Nature, Feb. 6, 1873. 464 HISTORICAL GEOLOGY. Cambrian, and in Murchison's expressing his satisfaction that geologists and paleontologists everywhere, in America as well as in Europe, had already adopted, through the use of his publications, his subdivisions and terms. Later, after collections of Cambrian or Primordial fossils had been much enlarged through new discoveries, the names Cambrian and Lower Silurian became accepted for successive divisions of the Paleozoic series. The term Cambrian is derived from the old name of Wales, and Silurian from the tribe of Silures, which inhabited southeastern Wales and Mon- mouth, England. For a more detailed history of the terms Cambrian and Silurian, see the Am. Jour. Sc., xxxix., 1890 ; also Murchison's Life by A. Geikie, 1875. AMERICAN. SUBDIVISIONS. 3. POTSDAM period, Reports New York Geologists, 1838, 1842. UPPEB CAMBRIAN, Walcott. LATER CAMBRIAN. 2. ACADIAN period, Dawson, Acad. Geol., 1868. MIDDLE CAMBRIAN, or Paradoxides zone, Walcott, 1887. Named Acadian from the locality at St. John, New Brunswick. 1. GEORGIAN period, 1886; LOWER CAMBRIAN or Olenellus zone, 1887, C. D. Walcott, Bull U. S. G. S. Keweenawian, T. B. Brooks, Am. Jour. Sc., xi. 206, 1876; Keweenawan, Chamberlin, 1883; Irving, 1887; Keweenian, A. Winchell, 1886. ROCKS KINDS AND DISTRIBUTION. General Distribution. The Cambrian rocks rest upon the upturned Archaean terranes, and usually outcrop along the borders of Archaean areas. In eastern North America they occur, adjoining the Archaean nucleus, on one or both sides of the Appalachian protaxis, from Canada to Alabama, and occupy parts of some, if not all, of the channels or troughs of Archaean con- fines from the Adirondacks to the eastern limits of Newfoundland. They are in part beach-made and wind-made sandstones, or offshore limestones, or slates or schists that originally were mud beds ; and the layers often bear ripple-marks, shrinkage cracks, worm-burrows, and, in some places, tracks of animals. Similar relations to the Archaean exist at various localities of the Lower Cambrian over the continent, to the far west. They, are found about Ar- chaean outcrops in Texas and South Dakota, and along the Eocky Mountain protaxis in British America and the United States, and also farther west in Nevada ; and occasionally they are reached, over the Pacific slope, by the canon cuts of rivers thousands of feet in depth, as in that of the Colorado. The accompanying sketch of a portion of the " Pictured Rocks " in the Lake Superior sandstone, near Carp River, Michigan, illustrates the usual PALEOZOIC TIME CAMBRIAN. 465 unconformability between the Cambrian beds and the Archaean, exempli- fying the fact that the upturned Archaean made the bottom of the Cambrian seas, over which the great sandflats, or other sand depositions, were made. The view also shows that the Cambrian beds had been slightly tilted since their formation. 505. Unconformability at Carp River, Chippewa County, Mich. J. D. Whitney. The fossiliferous beds in eastern Newfoundland of the Lower Cambrian consist of shales, sandstones, and conglomerates, of shallow water origin, and are hence evidence that the Cambrian continent stretched eastward as far as the existing continent. It probably had the Pacific for its western border ; for through the investigations, principally of C. D. Walcott, out- crops have been discovered over the Rocky Mountain border to points within 500 to 400 miles of the Pacific coast ; and further investigation is likely to carry the discoveries as far west as Archaean ridges exist. In the Lower Cambrian region of South Mountain, southeastern Penn- sylvania, west of the Susquehanna and in the adjoining part of Maryland, the Cambrian series overlies unconformably, according to the study of the rocks, and the region, by Gr. H. Williams and C. D. Walcott, beds and dikes of various igneous rocks, as basalts and rhyolytes, and also tufaceous accu- mulations of the same origin (1892, 1894). The Keweenaw Group, probably Lower Cambrian. No allusion is made above to the Keweenaw group, because it was a local formation. It occupies a belt of country on the south side of Lake Superior, covering Keweenaw Point, where it is best displayed, and extending from thence westward. It is called the copper-bearing sandstone formation from its characteristic rocks and its noted copper mines. But the feature of greatest geological DANA'S MANUAL 30 466 HISTORICAL GEOLOGY. significance is the igneous origin of a large part of the formation. Sheets of basic igneous rocks, partly amygdaloids, with others of felsyte, porphyry, and granite, are interstratified with the sandstones and conglomerates, and the latter are largely made of water-worn detritus of like igneous origin. The beds are wholly unmetamorphic to the bottom, and hence there is nothing in them to prove that the formation is Archaean. At the same time, no fossils have been found to prove it Cambrian. Still, inasmuch as it overlies unconformably the upturned Huronian, it must be of sub- sequent origin ; and as no Cambrian rocks occur in Wisconsin older than the Middle Cambrian, it is reasonable to suppose that it may represent the Lower Cambrian. The absence of fossils may be owing to the region's having been under fresh water, or to the igneous action. The copper veins of the Kewee- naw region have been discussed on page 341, under the head of Veins. It is important to note, however, that the igneous effusions which accom- panied the deposition of beds below the Lower Cambrian in southeastern Pennsylvania and the adjoining borders of Maryland, are similar, as Williams remarks, to the rocks of the Keweenaw series not only in kinds, but also in the presence of much metallic copper. Walcott and Williams conclude that the eruptions in the two areas were simultaneous and alike pre-Cambrian. Bearing of the facts connected with the distribution of the Cambrian on questions as to the upturning preceding the era. From the facts observed in connection with the distribution of the Cambrian over the Archaean of northern New York and Canada and in Archaean troughs to the eastward, it appears to follow that the mountain ranges in eastern America that were made at the close of the Archaean, and that stand as the time-boundary between the Archaean and Paleozoic, include the Adirondacks, the Appa- lachian protaxis, and other more eastern ridges ; and that these mountains consist, in part, if not largely, of rocks that were laid down as sediments during the long Huronian era, though now crystalline or metamorphic and in part massive crystalline. The disturbances closing Archaean time do not appear to have extended their effects alike over the whole surface of the continent, but to have produced their chief uplifts along the mountain borders ; that is, in those regions in which the most extensive mountain- making occurred in later time. Over the Continental Interior, the Huronian sediments were thinner, the upturnings at the epoch of disturbance less prominent, and the metamorphism feebler, where not wholly wanting. Walcott has classified the areas of geographic distribution of the surface outcrops of the Cambrian strata as follows (Bull. 81, U. S. G. ., page 358) : A. Atlantic or Eastern Border Province : a, Eastern or Nova Scotia Basin; 6, South- eastern Newfoundland, Eastern New Brunswick and Massachusetts Basin ; c, Interior Deposits of Gaspe, Quebec, Maine, New Hampshire, Vermont, Massachusetts. B. Appalachian or Interior Eastern Border Province. C. Rocky Mountain or Western Border Province. D. Interior Continental Province: D 1 , Central Interior, or Upper Mississippi and Missouri ; D 2 , Eastern Interior, or Adirondack of New York and Canada ; D 3 , Western Interior, or Dakota, Wyoming, etc. ; D 4 , Southwestern Interior, or Arizona and Texas. PALEOZOIC TIME CAMBRIAN. 467 Eastern Border Region. In southeastern Newfoundland, on Manuel's Brook, occur shales, with some limestone, overlying a conglomerate, in all 400' ; above occur beds with the Paradoxides fauna, and below it, within 40' of the conglomerate, species of the Olenellus fauna; the former occurs also at Topsail Head and on Conception Bay (Walcott). In the Acadian trough, Lower Cambrian fossils are reported from the north side of the Straits of Belle Isle, at L'Anso au Loup, and on the opposite coast at Canada Bay, Labrador ; Middle Cambrian, as gray and black shales, in New Brunswick, near St. John, with also Upper Cambrian beds ; in eastern Massachusetts ; the Lower Cambrian at Nahant, and in Bristol County, near northeastern Rhode Island, and the Middle Cam- brian at Braintree, where a thick conglomerate, much flexed, underlies 500' to 1000 7 of slate. Continental Interior Region (west of the Appalachian protaxis). Along the Green Mountain region in Vermont and Massachusetts, among the rocks of the Taconic series, a great quartzyte formation, having intercalations of hydromica and mica schist and occa- sionally ottrelite schist, has been shown by fossils to be in part or wholly Lower Cam- brian. The Sillery sandstone of Logan, in Canada, is part of the quartzyte formation. The limestone (white marble), adjoining the quartzyte on the west, has afforded Lower Cambrian fossils to the eastward and northward of Rutland. The continuation of this limestone belt, in Massachusetts, called the Stockbridge limestone, is too highly crystalline for fossils ; it may be in part Cambrian. West of the Taconic limestones in central Ver- mont, Lower Cambrian is represented by the red sandrock of the region. In north- eastern Vermont, at Georgia, magnesian limestone, 1000' thick, is overlaid by a great thickness of shales ; at Highgate the same limestone is 1200' thick. The reddish, mottled " Winooski limestone," of the Georgia Cambrian, is worked for marble at Swanton. West of the New England line, Lower Cambrian occurs in Washington County, New York, near Bald Mountain and elsewhere ; in the western part of Rensselaer County, at Troy, in shales and limestone and at Schodack Landing ; at several places in Dutchess County, at Stissing Mountain, where Middle Cambrian fossils also occur. West of Lake Champlain, about the Adirondacks, the Potsdam sandstone, chiefly Upper Cambrian, has a thickness in St. Lawrence County of 60' to 70' ; in St. Lawrence valley, of 300' to 600' or more ; in Warren and Essex counties, of about 100'. But in Dresden, Washington County, it occupies a depression at a height of 912' above Lake Champlain. A lower portion of the sandstone, according to Walcott, is Middle Cam- brian. In New Jersey, Sussex County, at Hardistonville, Olenellus occurs in sandstone, and other Cambrian fossils in the Magnesian limestone near Franklin Furnace, and north of Franklin Furnace Pond (C. E. Beecher). Foerste has found the Olenellus fauna in the same region, and also south of Sparta Junction, northeast of Long Pond ; and he has traced it south west ward into eastern Pennsylvania ; he shows that the quartzyte of the region, instead of being Potsdam Upper Cambrian, is mostly Lower Cambrian as in Ver- mont (1893). The Lower Cambrian has been traced by Walcott from New Jersey southwestward across Pennsylvania. In southeastern Pennsylvania, west of the Susquehanna, over parts of York, Adams, Franklin, and Cumberland counties, about South Mountain, east of the river in Lancaster County, and in adjoining parts of Maryland, the Lower Cam- brian includes a great thickness of quartzyte with overlying shales or slates and limestone ; and besides these rocks there are, in South Mountain, large flows of basaltic and rhyolytic rocks. In Virginia, fossiliferous shales of the Lower and Middle Cambrian occur near Natural Bridge and Balcony Falls. W. B. Rogers states, in connection with a contribution on the geology of Virginia to Macfarlane's Geological Railway Guide (1879), that the "Potsdam or Primal Group, where complete hi Virginia, includes, besides the Potsdam sandstone proper, the ferrife- 468 HISTORICAL GEOLOGY. rous shales next above, and the slates, shaly grits, and conglomerates, below, this formation. It is exposed on the western slope and in the west flanking hills of the Blue Ridge, through much of its length, often, by inversion, dipping to the southeast, in seeming conformity beneath the older rocks of the Blue Ridge, but often, also, resting unconformably upon or against them." These statements are cited from the Reprint of the Annual Reports of 1835-1841, and Other Papers on the Geology of the Virginias, by the late W. B. Rogers, 1884. In Tennessee, the Lower Cambrian comprises the u Chilhowee " sandstones of Safford, and beneath these, probably, the Ocoee conglomerates and sandstones. West of Cleveland, in east Tennessee, it includes the lower part of the Knox sandstone of Safford (the Rome sandstone of Hayes, in Georgia), and the thick formation of limestone and shales below ; while the central and upper portions of the Rome sandstone are Middle Cambrian. The same succession occurs near Knoxville. The Upper Cambrian is probably represented by the lower 2000' of the Knox dolomyte. The typical New York fauna of the Upper Cam- brian has not been recognized along the Appalachians in Pennsylvania, nor to the south- west. Lower Cambrian fossils have been observed in the lower part of the Rome sandstone near Rome, Ga., and in the limestones and shales of the Coosa series, in Coosa valley, Alabama, north and south of Cedar Bluff. In northwestern Michigan and Wisconsin, south of Lake Superior, the Lake Superior sandstone, on the borders of the lake, rests unconformably on the Keweenaw formation, and is referred to the Cambrian. A broad area of Upper and Middle Cambrian with fossils skirts the Archaean area on the east and south, and consists of crumbling sandstone and arenaceous shale, with, in some places, much green sand (glauconite), and thin beds of limestone ; the maximum thickness is 1000'. The quartzyte occurring in isolated hills in the drift-covered region of Wisconsin in Barren County, and at Baraboo in Sauk County (the Baraboo quartzyte), is made Huronian by Chamberlin and Irving, but Lower Cam- brian by N. H. Winchell. At St. Croix River, the horizontally bedded Upper Cambrian rests on upturned red beds, which are Middle or Lower Cambrian, and are continuous with the pipestone quartzyte of southwestern Minnesota, where Lingulse have been found; in this quartzyte, the pipestone bed (Catlinite), used for making pipe bowls by the Indians, is a layer of red argillaceous sandstone about a foot thick ; the rock passing south into Iowa is the "Sioux quartzyte" of C. A. White, and extends 10 miles into Dakota to Sioux Falls. With regard to the fact of unconformability with the Archsean at Carp River, Pro- fessor J. D. Whitney states, in a letter to the author of Nov. 7, 1893, that " nothing could be clearer" ; that u along the shores of Carp River and throughout the adjacent region, the sandstone strata are recognized as overlying the well-characterized beds of a much older formation which I designated as the 'Azoic Series.' At Carp River the nearly horizontal unaltered sandstone strata abut against and overlie the vertical edges of a well-marked quartzyte." The Lower Magnesian series of Missouri, excepting the First, or Upper, lime- stone of the series, and the underlying Saccharoidal sandstone, is Cambrian. It consists of alternating strata of dolomyte and sandstone. This Lower Magnesian series of Missouri is the Ozark series of Broadhead. The Keweenaw beds were described by Foster and Whitney in 1850, 1851, and referred to the age of the Potsdam or Cambrian. The more recent reports are by Irving (1880, 1883, 1885) and Chamberlin (1883) ; and, with special reference to copper mining, by M. E. Wadsworth in 1880. The series consists of an upper division, consisting of ordinary sand- stone and shales, free from igneous material, made 15,000' thick by Irving, and a lower division, 25,000' to 30,000' thick, made up of detrital and igneous rocks, but chiefly the latter. Chamberlin gives the same aggregate thickness, 45,000'. The igneous rocks are doleryte (diabase) with porphyritic and amygdaloidal varieties, gabbros, and also acid rocks as felsyte, felsyte-porphyry, and others. (For a full account of the rocks, see Irv- ing, Report U. S. G. S., v., 4to, 1883.) As estimates of the thickness of upturned rocks PALEOZOIC TIME CAMBRIAN. 469 are always more or less doubtful, the above figures can be considered at the best as only ap- proximations. To the great thickness estimated there is the additional source of doubt referred to on page 451, under the Archaean. For if 45,000', the temperature in the bottom beds would have been 1800 F., supposing the increase of temperature downward to have been 1 F. in 25 feet of descent, or only twice as great as now ; and if 35,000', it would have been 1500 F., high enough for the complete metamorphisin of the lower beds in the series. And yet there is no metamorphism. The Animikie group, of slates, sandstones, quartzyte, etc., on the north shore of Lake Superior, at the east end of Minnesota, about Grand Portage Bay and beyond, has inter- calations of doleryte (diabase), gabbro, and other rocks, much like those of the Keweenaw formation. Supposed tracks or trails of marine animals, mentioned on page 446, are the only fossils yet found. The Cambrian age of the formation is considered probable by many geologists. The igneous intrusions are regarded as laccolithic by Lawson, and as related in time to those of the Keweenaw formation. Eastern Eocky Mountain slope. The Cambrian beds of the Black Hills are red sandstone and with fossiliferous limestone above, pertaining to the Upper Cambrian. In central Texas, the beds of the Llano formation of Walcott are confined to Llano and Burnet counties ; they rest on upturned beds referred to the Algonkian by Walcott (page 447). Rocky Mountain region and Pacific slope. Lower Cambrian beds occur in the Rocky Mountains of British America, on the Vermilion and Kicking Horse passes. At Cotton- wood Canon in Utah, the great section of the Wasatch has at bottom 3000' of quartzyte, and above this 250' of hard shales, affording Lower Cambrian fossils, some of them identical with eastern species ; then succeed Lower Silurian beds, the Upper Cambrian being absent. Above Ophir City, in Oquirrh Mountain, fossils occur in a limestone over sandstone, the whole 2300' thick. In Nevada, according to Walcott, in the Eureka dis- trict, a section of conformable high-dipping beds 7700' thick, contains below (1) 1500' of quartzyte ; (2) 3050' limestone, with Lower Cambrian fossils in the lower 500'; (3) 1600' shale, and above this 1200' of limestone, 350' of shale affording Upper Cambrian fossils at bottom. In the Highland Range, 125 miles south of the last, are 1450' of limestone and shales overlying 350' quartzyte which are Lower Cambrian, and above these, 3000' of massive limestone which are Upper Cambrian. Other sections occur east of Pioche ; at Silver Peak ; at the south end of the Tim- pahute Range. In Arizona, at the Grand Canon of the Colorado, 3000' to 5000' deep, underneath horizontal Carboniferous and Subcarboniferous beds, the lower the u Red Wall Group " of Powell, lie horizontally 700' to 800' of shales and sandstones, the Tonto group of Gilbert, made Upper Cambrian ; the highly tilted beds beneath are referred by Walcott to the Algonkian. In S. E. California, Inyo Co., Lower Cambrian (Wale., 1894). For an extended review of the Cambrian of America see Bull. 81, U. 8. G. S. (1892), by C. D. Walcott, to whom the science is indebted for the discovery of the larger part of the facts. LIFE. The life of the Cambrian, so far as known, was marine. The plants were Algae (seaweed). The animals thus far made out from the fossils are all Invertebrates. They include Sponges, Corals, Hydrozoans, Echinoderms, Worms, Brachio- pods, Mollusks of the divisions of Lamellibranchs, Pteropods, Gastropods and Cephalopods ; and also, among Arthropods, Trilobites and other Crusta- ceans. All these groups, excepting that of Cephalopods, were represented in the earliest of the three divisions of the era. 470 HISTORICAL GEOLOGY. 1. LOWER CAMBRIAN. 1. Protozoans. No Rhizopod remains have been detected, unless small concretion-like nodules, concentric in structure, occurring crowdedly in a Cambrian limestone in Nevada, are of this nature. They may belong to the genus Girvanella (Walcott). See page 501. 2. Sponges, Corals, Graptolites. Fig. 506 represents one of the Lower Cambrian sponges, Leptomitus Zittelli of Walcott, from Georgia, Vt. Figs. 507, 508 are of corals, though supposed, when described, and until investigated microscopically by Hinde, to be Sponges. Fig. 507 represents the Archceocyathus profundus of Billings, and 508, 508 a, views of Spirocyathus 506-509. 506. 507. 508. 609. 508 a. SPONGE. Fig. 506, Leptomitus Zittelli. CORALS, 507, Archaeocyathus prof undue; 508, Spirocyathus Atlan- ticus (i) ; 508 a, transverse section. GRAPTOLITB, 509, Climacograptus (?) Emmonsi. Figs. 506, 509, Walcott ; 507, 508, Billings. Atlanticus Billings. One of the early Graptolites (so called from the Greek ypauebecensis. All from Dawson. membrane. Only the finest of sediments were therefore adapted to their preservation. The forms with one row of cells, or one-edged (Monoprio- nidse), are represented by the Loganograptus (Figs. 604-606) and species of 604-609. 605 GRAPTOLITES. Fig. 604, Loganograptus Logani, branches broken off ; 605, portion of a stem ; 606, same, more enlarged ; 607, 608, Phyllograptus typus ; 609, the supposed young of a Graptolite. Hall. other genera. They occur either in long, flat, notched threads spreading from a center (Fig. 604), or in simple forms; but most specimens are only frag- PALEOZOIC TIME LOWER SILURIAN. 499 610. ments of branches of the slender polypary. The diameter of the form Fig. 604, when living, and having its arms of full length, may have been 15 to 20 inches. Figs. 607, 608 represent a species of the two-edged forms (Diprio- nidae), that is, those having cells along both margins. Besides Graptolites, there were massive Hydrozoan corals, of the JStroma- topora type, related, it is supposed, to the modern Millepora. Under Echinoderms, there were Crinoids and Cystoids, and also the earliest known of American Star- fishes (Fig. 610). Among the Brachi- opods, a common species is the Orthis (BilUngsella) grandceva (Fig. 611). Gastropods, of flat or short spiral forms, like Figs. 612-614, of species of the genus Ophileta and Madurea, were common, and some were of large size. The genus Platyceras continued on from the Cambrian. There were also spiral forms of the genera Pleu- rotomaria, Murchisonia, Holopea (Fig. 615), and others of the Bellerophon family. The shells of Cephalopoda in the Cal- ciferous beds occur of many and varied forms, and some are over a foot in length. Those of the genus Orthoceras are straight or slightly curved. In 0. primigenium of Vanuxem, first described from the Mohawk Valley, N.Y., the septa, as shown in Fig. 618, are closely crowded. A curved species is represented in Fig. 620, Cyrtoceras (?) Vassarinum from Dutches s County, N.Y. 612-616. Stenaster Huxleyi (x 4). Billings. Orthis (Billings- ella) grandseva. QASTBOPODS. Fig. 612, 612 a, Ophileta complanata (1), opposite sides; 613, O. levata (1); 614, 0. uniangulata (1); 615, Holopea dilucula. OSTBACOID CRUSTACEAN: 616, Leperditia Anna enlarged, side view; 616 a, same, upper view ; 616 b, several of the shells, natural size. Figs. 612, 612 a, Whitfleld ; 613, 614, 615, Hall ; 616, 616 a, 6, T. R. Jones. There were also coiled species, both the open-coiled of the genus Lituites, and others that were close-coiled, Nautilus-like. Lituites (?) imperator B., Philipsburg, Canada, had a diameter of 10 inches. 500 HISTORICAL GEOLOGY. 617-620. Trilobites existed of the Cambrian genera Agnostus, Dicellocephalus, Pty- choparia, Bathyurus (seven species or more), and Bathyurellus (Figs. 621-624), and also of the genera Illcenus, Asaplius, Ceraurus (Cheirurus), Amphion, Ampyx, which have here their first American species. An Ostracoid, or bivalve Crusta- cean, is represented much enlarged 617- 620. in Fig. 616 (a profile view in 616 a), and several of natural size in the rock in Fig. 616 b. Characteristic Species. 1. Spongiozoans. Beceptaculites ele- gantulus B. (Fig. 597) was a hollow sponge, with the thickness to the inner tube about half an inch ; tubes passed from the outer to the inner surface, which opened inward. The species from Little Metis (Figs. 599- 603) occur in beds that contain also the Brachiopod Linnarssonia pretiosa B. (Daw- son, Trans. Roy. Soc. Canada, 1889). The stem of Protospongia mononema (Fig. 600) is of doubtful reality, according to Hinde. 2. Hydrozoans. The characteristic Cal- ciferous forms, besides those figured, are Phyl- lograptus Anna H. , Tetragraptus bryo noides H., T. fruticosus H., Didymograptus exten- sus H., all of the vicinity of Quebec. The Cryptozoon proliferum H.(1884), from Green- field, Saratoga County, N.Y., and C. Steeli, Seely and Br. , another species from Vermont, if really organic, perhaps belong here. 3. Echinoderms. Stenaster Huxley i B. (Fig. 610), having a breadth of 5 lines, is from Point Rich, Newfoundland. 4. Molluscoids. Fig. 611, Orihte (Bil- lingsella} grandceva B. ; Lingula acuminata, Camarella calcifera B. ; C. varians B. (also from Newfoundland); Clitambonites. 5. Mollusks, a. Lamellibranchs. Eu- chasma Blumenbachii B., Newfoundland ; Tellinomya Angela B. 6. Gastropods. Ophileta compacta S., a fine species from Canada, is H inches across ; Pleurotomaria Calcifera B., from near Beauharnois, Canada; P. gregaria B., St. Ann's, island of Montreal, Canada, extremely abundant ; Maclurea matutina H., from New York and Canada ; Murchisonia Anna B. (a long turreted shell, approaching the M. bellicincta, Fig. 675), St. Ann's, the Mingan Islands; Eccyliomphalus priscus Whitf., a large open- coiled shell from Fort Cassin, Vt. c. Cephalopods. Orthoceras Ozarkense Shum. is from the Magnesian limestone, Ozark County, Mo.; Lituites (?) Farnsworthi B., a species partly coiled, and nearly 5 inches in its longer diameter, and L. imperator B. , are from the upper part of the Calcif erous sand- CEPHALOPODS. Figs. 617, 618, Orthoceras primige- nium; 619, Kionoceras (Orth.) laqueatum ; 620. Cyrtoceras (?) Vassarinum. Figs. 617, 618, 619^ Hall ; 620, W. B. Dwight. PALEOZOIC TIME LOWER SILURIAN. 501 rock of Philipsburg, Canada East; Piloceras Canadense B., from the Mingan Islands, north of Anticosti Island; P. Wortheni B., from western Newfoundland. Nautilus pomponius B. is from Philipsburg ; N. ferox B., Mingan Islands, is referred by Hyatt to the genera Plectoceras and Litoceras, there being no true species of Nautilus in Paleozoic rocks. At Philipsburg, Fort Cassin, and in Newfoundland, the fauna included also, accord- ing to Hyatt, species of the genera Sannionites (Fischer, Hyatt), Endoceras Hall, and Actinoceras Bronn (= Ormoceras Hall). On Hyatt's review of the genera of Fossil Cephalopods, see Proc. Boston Soc. Nat. Hist., xxii., 253, 1883. 621-624. 623. 621. 622. Figs. 621, 622, Bathyurus Saffordi; 624. 5, Bathyurellus nitidus ; 624, Bathyurus (?) crotalifrons. Figs. 621-623, Billings ; 624, Dwight. 6. Crustaceans. Among Trilobites, Bathyurus Saffordi B. (Figs. 621, 622) is com- mon in Canada, and occurs also in Newfoundland and Idaho ; B. crotalifrons at Rochdale, N.Y. ; B. armatus, Quebec and Saratoga County, N.Y. ; Ptychaspis speciosa, Ptychoparia Calcifera, P. Hartti, are other Saratoga County species. Bathyurellus nitidus B. (Fig. 623) is from Cow Head, Newfoundland. None of these species occur in the Trenton. The Calciferous fossils reported by S. Calvin from the Lower Magnesian limestone of Iowa are Metoptoma alta Whitfield, Straparollus Claytonensis Calvin, S. pristiniformis Calvin, Raphistoma Pepinense Meek, H. multivolvatum Calvin, Holopea turgida Hall, Orthoceras primigenium V., 0. Luthei Calvin. 2. Chazy Epoch. In the Chazy limestone occur small concretion-like forms (Fig. 625) hav- ing the structure represented in Fig. 626, which are supposed by some to be of vegetable origin, and by others, a Sponge or the secretions of Hydro- zoans. The Corals of the period include Cyathophylloids, a tribe that dates from the early Cambrian ; massive columnar Corals of the genus Colum- naria; and species with quadrangular cells, of the genus Tetradium this name, from the Greek for four, re- ferring to the form of the cells (see Fig. 707, page 511, for a Trenton species). One of the Cystoids is represented in Fig. 628, and the body of a Crinoid in Fig. 627. The stem is wanting in each. Xi';;S:iV;'fe:S;* Fig. 626, Girvanella ocellata; 626, interior enlarged. Seely. 502 HISTORICAL GEOLOGY. 1. Molluscoids. Fig. 630 shows a branching coral-like species of Bryozoan, Sulcopora fenestrata H., and Fig. 629 one of the reticulate kinds, Subretepora 627-638. 639. CBINOIDS. Fig. 627, Palseocrinus striatus; 628, Malocystites Murchisoni. MOLLUSCOIDS. 629, Subretepora incepta; 630, Sulcopora fenestrata; 631, Orthis costalis; 632, Strophoraena plicifera; 633, Ehynchonella plena. MOLLUSCS. 634, Maclurea magna; 635, M. Logani (x J); 635 a, operculum of same; 636, Scalites angulatus; 637, Bucania rotundata. CRUSTACEANS. 638, Leperditia Canadensis, var. nana. Figs. 627, 628, Billings; 629-634, and 636, 637, Hall; 635, 635 a, Salter; 638, T. E. Jones. incepta H. ; and Fig. a for each is an enlarged view of the surface. Some of the common Brachiopods are Orthis costalis H. (Fig. 631), Strophomena (?) plicifera, H. (Fig. 632), and Rhynchonella plena H. 2. Mollusks. Figs. 634 to 637 show the forms of various Gastropods; 634 is the very abundant Mac- lurea magna; it is often eight inches in diameter. Fig. 635 is a view of another species which shows also the operculum closing the aperture ; and 635 a is the separated operculum. Fig. 637, Bucania rotun- data, is related to Bellerophon. 3. Crustaceans. Ostracoid Crustaceans of the spe- cies Leperditia Canadensis (Fig. 638) are common. Several Cambrian genera of Trilobites, Dicellocephalus and others, had disappeared, Bathyurus had lost the prominence it had in the Calciferous era, and the genera Illcenus, Asaphus, Ceraurus, Amphion, were continued on with new species. Fig. 639 represents the pygidium of an Amphion. Arnphion Canadensis. Billings. 1. Rhizopods. Girvanella of Nicholson and Etheridge (1878), made by them doubt- ingly Foraminiferous, includes, according to its describers, Strephochetus (Figs. 625, 626) PALEOZOIC TIME LOWER SILURIAN. 503 of Seely (1885), who referred it to the Sponges, and Siphonema of Bornemann (1886), who placed it among the Algae. It is made a calcareous Alga by Rothpletz (1891). 2. Spongiozoans. Eospongia (Astylospongia) Bcemeri B. and E. varians B. occur at the Mingan Islands. 3. Actinozoans. Columnaria incerta B. and C. parva B. ; the Cyathophylloid, Streptelasma expansum H. ; Monticulipora patula B., M. adhcerens B., from Canada. 4. Echinoderms. (1) Crinoids. Palceocrinus striatus (Fig. 627), the body, show- ing the five radiating ambulacral grooves at top ; Blastoidocrinus carcharidens B. (2) Cystoids. Malocystites Murchisoni B. (Fig. 628) has the body nearly spherical (whence the name, from the Latin malum, an apple), the ambulacral grooves irregularly radiating; M. Barrandi B., Palceocystites tenuiradiatus B., which is common, and has been identified but doubtfully, from crinoid stems from crystalline limestone of West Rut- land (Am; Jour. Sc., III. iv. 133) ; also P. Dawsoni B., P. pulcher B., P. Chapmani B., from Canada. 5. Molluscoids. Other species are Bafinesquina incrassata H., which continues into the Trenton Strophomena (?) plicifera H., Rhynchonella acutirostris H., B. altilis H., Bafinesquina fasciata H., in the Upper Chazy ; Lingula Lyelli B., L. Huronensis B., etc. ; Orthis imperator B., a species nearly 1 inches across. NOTE. Hall proposes (1892) the generic name Bafinesquina for the species of Stro- phomena of the type of S. alternata, restricting the name Strophomena to resupinate species like S. planumbona. He applies the name Leptcena to forms like S. rhomboidalis, and restores Pander's generic name Plectambonites to species commonly known as Leptcena, as L. sericea and L. transversalis (Hall, Pal. N. Y., vol. viii., Genera of Paleozoic Brachi- opoda, 1892). 6. Mollusks. (a) Lamellibranchs. Cypricardites (Vanuxemia) Montrealensis B. a species nearly 1 inches long. (&) Gastropods. Besides the species figured, other common kinds are Baphistoma planistrium H., Pleurotomaria biangulata H., P. antiquata H., Bucania sulcata (Bucania differs from Bellerophon only in having the outlines of the spire show externally on either side). Metoptoma dubia H., Platyceras auriformis H. (c) Cephalopods. Orthoceras rectiannulatum H., also found in the Birdseye lime- stone ; O. tenuiseptum H., septa very thin and rather crowded ; O. velox B., Montreal, Mingan Islands; O. diffidens B., Mingan Islands; 0. Allumettense B. (which is also a Black River limestone species). 7. Crustaceans. The Trilobites, Illcenus Arcturus H.; Asaphus obtusus H., A. (Iso- telus) canalis Conr., New York and Canada, A. marginalis H., and also Quebec group of Newfoundland. Bathyurus Angelini B.; Ceraurus Satyrus B., at Montreal. The earlier genera, Dicellocephalus, Crepicephalus, Menocephalus, Bathyurellus, Loganellus, Nileus, are not represented, so far as known, in the Chazy or later periods. The Ostracoids, Leperditia Canadensis Jones, Fig. 638, from Grenville, Huntley, and elsewhere in Canada ; L. amygdalina Jones, from near L'Original, Canada. In the gorge of the Kentucky River, near the mouth of Cooper's branch, Ulrich reports a limestone stratum (150' thick) as affording the Chazy species Maclurea magna, Baph- istoma planistrium, Bhynchonella dubia H., Sulcopora fenestrata, Leperditia Canadensis, with Orthis subcequata Conr. a Trenton species, Orthoceras explorator B. a Quebec species and 0. furtivum B. a Calciferous species ; with also species of Bathyurus, Dalmanites, Pterotheca, and the Trenton Bryozoan Mitoclema cinctosum Ulr. Other species described by Billings, in Can. G. Bep. of 1863, are Monticulipora (Sten- opora) fibrosa ; Bhynchonella orientalis, Camarella varians, C. longirostris, Orthis platys, 0. borealis, O. Porcia, O. acuminata, 0. disparilis Con. (from the Chazy and Trenton) ; Pleurotomaria calyx, P. docens ; Illcenus globosus, I. Bayfieldi, Sphcerexochus parvus (from the Chazy and Black River), Harpes antiquatus. 504 HISTORICAL GEOLOGY. 2. TRENTON PERIOD. 1. Trenton Epoch. PLANTS. Two of the forms referred to Algae or Seaweeds are here repre- sented. They are much like the so-called Fucoids of earlier and later time; but whether of vegetable origin is questioned. 640. 641. ALG.E. Fig. 640, Buthotrephis gracilis ; &41, B. succulens. Hall. Specimens of supposed terrestrial plants have been reported from the Cincinnati beds of Ohio and Kentucky ; but no certain evidence from fossils of vegetation over the land had been found up to the year 1894. 642. 643. SPONGE. Brachiospongia digitata. Beecher. ANIMALS. 1. Spongiozoans. A large branching Hexactinellid Sponge, Brachiospongia digitata, from the Trenton of Kentucky and Tennessee, is represented in different positions in Figs. 642, 643. The number of short branchings varies from 8 to 12, and specimens having 12 are sometimes 10J inches in diameter. 2. Hydrozoans are represented by Graptolites (647, a) and Stromatoporids. 3. Actinozoans comprise Cyathophylloid Corals like Fig. 644, Streptelasma comiculum H. ; and tabulate Corals as Columnaria alveolata H., the term tabulate referring to the horizontal partitions seen in vertical sections of the columnar cells (Fig. 645). PALEOZOIC TIME LOWER SILURIAN. 505 There were also many of the minutely columnar Corals, of the Monticuli- pora family, differing from Ohcetetes, to which genus they were formerly referred in having the columns separable. Prasopora lycoperdon, Fig. 646, is a hemispherical species, having the structure shown in Fig. 646 a ; others are branching and foliaceous forms. The branching Corals which form the crystalline points called "birdseyes" in the Birdseye limestone are 644-651. RADIATES. Fig. 644, Streptelasma corniculum; 645, Columnaria alveolata; 645 a, surface showing cells; 646, Prasopora lycoperdon ; 646 a, transverse section of same ; 647, portion of Diplograptus amplexicaulis ; 647 a, same enlarged ; 648, Palaeaster matutinus ; 649, Taeniaster spinosus ; 650, Taxocrinus elegans ; 651, Pleuro- cystites filitextus. Figs. 644, 645, Hall ; 646, 647, Meek ; 648-651, Billings. referred to the genus Tetradium, distinguished by its four-sided cell with four points within it, as in Fig. 707, page 511. These peculiar fossils were first called Fucoids by Conrad, and later named Phytopsis cellulosa by Hall, the generic name referring to the resemblance to plants. 4. Echinoderms include true Crinoids (Fig. 650), Cystoids (Fig. 651), Asterioids, under which are true Starfishes (Fig. 648), and the Ophiuroids or Serpent-star (Fig. 649). 5. Molluscoids. Three species of the Trenton Bryozoans are represented on the next page from a memoir by Ulrich (1893); Fig. 652, of a Stictoporella, represents the retiform frond of natural size, and 653, a portion between two of the spaces much enlarged, showing the cells. Fig. 654 is a jointed branch- ing form from Ottawa, Canada, natural size, and 655 represents three joints much enlarged. On page 507 are figures of common Trenton Brachiopods of the genera and species named underneath. The figures are mostly from specimens 506 HISTORICAL GEOLOGY. obtained in the beds of Cincinnati of the Hudson period, and in part differ somewhat in habit from those of the Trenton limestone. 652-655. 652. 653. BKYOZOANS. Fig. 652, Stictoporella cribrosa (1) ; 653, same (x 18) ; 654, Arthroclema Billingsi (1) ; 655, A. cornutum (x 7). Ulricli. 6. Mollusks. Some of the Lamelli- branchs are figured in Nos. 670-672, and also 709-712 (page 511) ; and Gastropods in Figs. 673-681. Fig. 673 represents a Ra- phistoma-y 674, 675, species of the genus Murchisonia ; 677, 678, a Belleroplion in different views ; and 679-681, species of the related genus Cyrtolites, symmetrical shells of swimming Mollusks, related to the modern Atlantis (Heteropods). Pteropods were represented by species of Pterotheca, and of Conularia; in the latter, the shell admits of some movement along vertical sutures (Fig. 682). A few of the shells of Cephalopods are represented on page 508 : Fig. 683, Orthoceras junceum H. ; the cross-lines representing the partitions or septa, and Fig. a, a transverse section, showing the position and size of the siphuncle. Fig. 685, part of the shell of Actinoceras Bigsbyi of Bronn (1837); the whole length of the shell when entire was over a foot; the view is of a section showing the large beaded siphuncle within ; 686, Cyrto- ceras subannulatum D'Orb. ; and 687, 688, species of Trocholites, T. undatus and T. Ammonius of Conrad. In another genus, Endoceras, from the Black River limestone, some specimens have a diameter exceeding a foot, and a PALEOZOIC TIME LOWER SILURIAN. 507 length of 10 or 12 feet. They were the largest and most powerful animals of the seas ; but they must have been much encumbered in locomotion by the long bulky shell. 656-669. BEACHIOPODS. Figs. 656, 657, Orthis (Platystrophia) biforata ; 658, O. occidental ; 659, O. testudinaria ; 660, O. tricenaria ; 661, Leptaena (Plectambonites) sericea ; 662, Leptsena rhomboidalis ; 663, Strophomena (Eafi- nesquina) alternate ; 664-666, Rhynchonella capax ; 66T, 66T a, Cyclospira bisulcata ; 668, Schizocrania filosa ; 669, Lingula quadrata. Figs. 656-666 from Meek ; 66T-669, from Hall. 670-682. 671 LAMELLIBEANOHS. Pig. 670, Pterinea Trentonensis; 671, Ambonychia bellistriata; 672, Tellinoinya nasuta. _ GASTROPODS. Fig. 673, Eapbistoma lenticulare; 674, Murchisonia Milleri ; 675, M. bellicincta ; 676, Helicot- " oma planulata; 677, 678, Bellerophonbilobftus; 679, Cyrtolites compressus ; 680, 681, C. (?) Trentonensis ; 682, a, b, Conularia Trentonensis. Figs. 670, 671, 677-682, Hall ; 672, Billings ; 673, 675, Meek ; 674, 676, Salter. 508 HISTORICAL GEOLOGY. The genus Orthoceras had many later species. But Endoceras, of which there are over twenty described American species, began in the Canadian and ended in the Trenton period. 683-688. CEPHALOPODS. Fig. 683, a, Orthoceras junceum ; 684, 0. olorus (x%) ; 685, Actinoceras Bigsbyi; 686, a, Cyr- toceras subannulatum D'Orb. ; 68T, Trocholites undatus ; 688, T. Ammonius. Figs. 683-687, Hall ; 688, D. 7. Crustaceans. Trilobites were of varied forms and many new genera ; Asaphus, a Calciferous genus, holds on ; and so also Illcenus, Ceraurus, and Bathyurus; the latter two have their last species in the Trenton. Fig. 689 represents Asaphus platycephalus, from Trenton Falls, N.Y., which is often 689-693. 690 CBUSTAOKANS. Fig. 689, Asaphus (Isotelus) platycephalus (x %) ; 690, a, Calymene callicephala ; 691, Lichas Trentonensis ; 692, Trinucleus concentricus ; 698, a, 6, Leperditia fabulites (natural size). 689, 691, Hall; 690, 692, Meek ; 698, T. K. Jone* PALEOZOIC TIME LOWER SILUKIAN. 509 eight inches long ; Calymene (Figs. 690, a) is still more common, 690 a showing it rolled up, as is often the case (like a modern Oniscus among Crustaceans); 691, zLichas; 692, Trinucleus concentricus (the name referring to the three prominences on the head, and its fillet-like border) ; all are found at Trenton Falls. Another common Trenton species is the Ceraurus pleurexanthemus Green. Fig. 694 represents an under view of the shell the ex- uvia of the Trilobite. Walcott states that out of 1160 specimens found by him, only 50 lay with the back upward, a natural con- sequence of their being mere empty exuviae, as they would be likely to float like a boat, with the concavity upward. Crustaceans of the Ostracoid tribe are not rare. A Leper ditia is represented in Fig. 693. 8. Fishes. Remains of Fishes, the earliest known Vertebrates, OCCUr TKiLOBrra.-Fig. 694, Ceraurus pleurexanthemus, under in rocks Of the Trenton period. surface, natural size: 2, the hypostome; 4,5, occipital __.. , . , , depression and cavity ; a, b, c, d, depressions in the The discovery was announced by 8hell of the thorax . e> free pleune mlcottj , 75 Walcott in 1891. The fossils are abundant in sandstone near Canon City, Col. Most of them are the plates and scales of Ganoids, the largest about half an inch across. Of 695-697. 695. 695 a. 097 a 697. BEMAIXS OF FISHES. Fig. 695, Astraspis desiderata, dermal plate; 695 a, id. (x 3); 696, Eriptychius Ameri- can us (x 4) ; 697, 69T a, Dictyorhabdus priscus, supposed notochord. Walcott. 510 HISTORICAL GEOLOGY. these plates, two, represented enlarged in Figs. 695, 695 a, are referred to Placoderms (see page 417), the group which comprises the oldest Fishes previously known, those of the Upper Silurian and early Devonian. The scales, Fig. 696, have the markings of a typical Ganoid, much like those of the genus Holoptychius, a form not found hitherto in beds earlier than the Middle Devonian. Besides these, there are remains (Figs. 697, 697 a) of what are supposed to be the ossified sheaths of the notochord of a species of the Shark tribe related to the Chimaera (page 416). The beds affording these remains of Fishes contain many other fossils that are referred to the Lower Trenton, and are overlaid by others carrying Upper Trenton fossils. 2. Utica and Hudson Epochs. Graptolites abound in the shales of the Utica and Hudson groups, especially the former. Thirty species or more have been described from the Utica slate, and some of these are represented in Figs. 698-702. 698-703. GRAPTOLITES. Fig. 698, Lasiograptus (Diplograptus) mucronatus; 699, Ccenograptus gracilis ; 700, Clima- cograptus bicornis ; 701, 701 a, Diplograptus pristis ; 702, Dicranograptus ramosus. ASTERIOI i>. Fig. 703, Palaeaster Jamesi. Figs. 698-702 from Hall ; 703, J. G. Anthony. Corals occur of several genera. Favistella, Fig. 704, is a massive Coral, with crowded stellate cells. Halysites, Fig. 705, grew in vertical plates, in- tersecting one another ; in a transverse section the cells look like the loops of a chain, whence the common name chain coral. Another Coral grew in PALEOZOIC TIME LOWER SILURIAN. 511 clustered stems, Fig. 706, with the cells above stellate. A species of Tetra- dium, T. fibratum of Tennessee, is represented in Fig. 707. Minutely columnar Bryozoan corals of the Monticulipora tribe were very numerous, 70 or 75 species having been described from the Cincinnati beds. 704-708. 70S Fig. 704, Favistella stellate ; 705, Halysites gracilis ; 706, Sarcinula (?) obsolete ; 707, a, Tetradium fibratum ; 708, Glyptocrinus decadactylus. Hall. The Echinoderms included Crinoids and Cystoids of several kinds. Fig. 708 represents a fine Glyptocrinus, one of the most common ; and Fig. 703, a remarkable Star-fish from the Cincinnati beds, Palceaster Jamesi D. Two other fine Star-fishes from the same locality (P. Dyeri Meek and P. magnificus 709-712. LAMELLIBRANCHS. Fig. 709, Avicula demissa ; 710, Ambonychia radiate; 711, Modiolopsis modiolaris (x f) ; 712, Orthodesma parallelum. Hall. Bryozoan corals also are com- 713. Miller) have a diameter of about six inches, mon in the Cincinnati beds. The Brachiopods are nearly the same as in the Trenton. Lamellibranchs are rather common, they being usually more abundant in shales and shaly sandstones than in lime- stones. Some of the kinds are shown in Figs. 709-712. Of the Gastropods represented on page 507, Figs. 673-675 are also Hudson group species ; and the same is true of the Lituites ^Trocholites} Ammonius, Fig. 688. Of Cephalopods, the Cincinna>i beds 'have afforded 13 species of Orthoceras, 5 o| Endoceras, 4 of Lituites, and 10 of other genera. Head-shield of Triar- thrus Beckii. 512 HISTORICAL GEOLOGY. The Trilobites include Asaphus platycephalus, Fig. 689; a still larger species, A. megistos Locke, over a foot long, the Calymene of Fig. 690, Lichas of Fig. 691, and Trinudeus of Fig. 692. The most common species is the Triarthrus Beckii, and the remains usually found are simply the head-shield, represented in Fig. 713. The 714. i 715. 716. TBILOBITES. Fig. 714, Triarthrus Beckii, nat. size; 715, a to t (x 3), young of same, at different stages of growth ; a , the youngest stage (x 15). Fig. 714, Beecher ; 715, a to i, Walcott. nearly entire Trilobite, having its tentacles and many of its legs protruded, found as yet at but one locality on the continent, near Rome, N.Y., is shown in Fig. 714, from a sketch by C. E. Beecher. Less perfect speci- mens, from the same place, as figured by Matthew, are represented on page 422. The legs of the left and right sides of Fig. 714 are from two different specimens, bub are not in any respect " restored." Each has, as made known by Beecher, two branches, and one of them is fringed, and thereby natatory in function. The natatory branch is strictly an append- age to the basal joint of the other branch, which is the true leg. In Fig. 716 A the fringe is removed to show the articulations ; in 716 B the limb is in its entire state. Beecher's observations make certain the close relations of Trilobites to Isopod Crustaceans, as stated on pages 421, 422. 717. Fig. 716. A, B, leg of Triarthrus Beckii (x 12) ; A, leg with the setae removed to show the articulations, en, the main stem of the leg (endopodite); ex, the natatory branch (exopodite). Beecher. Embryonic form of Triarthrus Beckii (x 80). Beecher. PALEOZOIC TIME LOWER SILURIAN. 513 718. CIRRIPEDB. Fig. 718, Turrilepas Cana- densis, a single plate (X 5). Under Fig. 715 are figures of the young Trilobite at different stages of growth, as made out by Walcott all magnified three times excepting a 1 , which is the stage a magnified 15 times. In this young stage the thorax has but one thoracic segment, and this has a short spine on the back ; the following five segments are abdominal. The other figures (b to i) have an increasing number of thoracic segments. Walcott figures 12 of these stages of growth below the adult, and nine are here reproduced. Beecher has observed a still younger stage having no thoracic segment, represented, mag- nified 30 times, in Fig. 717. Other genera of Trilobites of this epoch are Ceraurus, Acidaspis, Proetus, Dalmanites, and Cyphaspis. Besides Ostracoids of several genera, there were also the first known species of the Barnacle or Cirriped tribe the Turrilepas Canadensis Woodward. The specimen figured (Fig. 718), rep- resenting one of the pieces of the shell, was from near Ottawa, Can- ada. The Utica slate has afforded the first speci- mens of the Eurypte- rids species remotely related to Crustaceans, and peculiar in having five pairs of large legs projecting either side of the head whose basal joints serve as jaws (page 556). Fig. 719 rep- resents a leg of one of the pairs ; and as it is half the natural size, the whole animal was probably more than a foot long. Its fringe of spines aided it in swimming, and perhaps also in securing its food. Entire specimens of other species of the tribe are shown on pages 556, 564. Characteristic Species. 1. Trenton Epoch. 1. Spongiozoans. Eeceptaculites Oweni H., characteristic of the Galena limestone, with H. globularis H., It. lowensis Owen. Astylospongia parvula Bill., near Ottawa City, Canada ; Brachiospongia digitata (Fig. 642) is from a paper by C. E. Beecher, which is illustrated by 6 plates, published by the Peabody Museum of Yale College. The species was first described and figured by Troost in 1839 ; named Scyphia digitata by D. D. Owen in 1858, and Brachiospongia Koemerana by Marsh in 1867. Beecher also describes in the same paper two other species of Sponge under the generic name Strobilospongia ; they occur with the preceding. The most recent observations of Rauff make the supposed relations of the Receptaculites to the Sponges very doubtful. 2. Actinozoans. Fig. 644, Streptelasma corniculum H., 8. profundum Con., Trenton limestone; S. apertum B., Black River limestone. Fig. 645, Columnaria alveolata Goldf., Black River limestone, and Trenton ; C. Halli Nicholson, Kentucky ; C. calicina Nicholson, DANA'S MANUAL 33 Fig. 719, Leg of Echinognathus Cleveland!. Walcott. 514 HISTORICAL GEOLOGY. from Kentucky ; Figs. 646, 646 a, Prasopora lycoperdon ; Halysites catenulatus or related, Galena limestone, and in Canada; Tetradium columnare H., Tennessee. 3. Hydrozoans. Fig. 647, Diplograptus amplexicaulis H., New York and Tennessee ; 647 a, enlarged ; Climacograptus ; Stromatocerium pustulosum Saff., Tennessee. Soleno- pora compacta B., Canada, eastern New York, Kentucky, looks like a pebble, and a limestone made largely of them resembles a conglomerate. It occurs abundantly at Pleasant Valley, in Dutchess County, N.Y. (D wight). 4. Echinoderms. Fig. 648, Palceaster matutinus H., of the Trenton ; 649, Tceniaster spinosus B. ; the Crinoids, Taxocrinus elegans B. (Fig. 650), Agelacrinus Billingsi Chap- man, Grlyptocrinus decadactylus H., Kentucky, Schizocrinus nodosus H., Heterocrinus Canadensis B. ; also species of genera ffybocrinus, Porocrinus, Palceocrinus ; and the Cys- toids, Comarocystites Shumardi M. & W., Missouri, C. punctatus B., Canada ; Dendrocrinus. retractilis Wale., Trenton Falls, Calceocrinus Barrandei Wale., ibid. ; Merocrinus typus Wale., ibid., locrinus crassus H., ibid. ; Fig. 651, Pleurocystites filitextus B., Amygdalo- cystites, Kentucky. 5. Molluscoids. (or) Bryozoans. Species of Stictopora and Ptilodictya (related to Figs. 629, 630) are common ; Clathropora flabellata H. ; Stomatopora arachnoidea H. (&) Brachiopods. Figs. 656, 657, Orthis biforata Schl. ; 658, O. occidentalis H. ; 659, O. testudinaria Dalm. ; 660, 0. tricenaria Con., O. disparilis H., 0. subquadrata H. t and others ; 661, Leptcena (Plectambonitcs} sericea Sow. ; 662, Leptcena rhomboidalisWilc. ; 663, Strophomena (Rafinesquina) alternata Con., S. incrassata H. ; 664-666, Rhynchonella capax Con. ; 667, 667 a, Cyclospira bisulcata Emm. ; Zygospira modesta Say ; 668, Schizocrania filosa H. ; Crania scabiosa H., Galena limestone ; 669, Lingula quadrata Eichw. , and other species ; also species of Orbiculoidea, Trematis, etc. 6. Mollusks. (a) Lamellibranchs. Tellinomya alta H., Wisconsin, etc. ; Am- bonychia attenuata H., Wisconsin, and others ; Conocardium immaturum B., Black River limestone, Ottawa ; Modiolopsis faba H., M. superba Bill., Wisconsin, etc.; Cypricardites Niota H., Wisconsin, C. rectirostris. (&) Gastropods. Fig. 673, Raphistoma lenticulare Emm., very common; Pleuro- tomaria subconica H., and other species; 674, Murchisonia Milleri; 675, M. bellicincta H., often 4 inches long, M. gracilis H., M. tricar inata H. ; 676, Helicotoma planulata Salter, Canada, Cyclonema bilix Con., Ophileta Owenana M. & W., Galena limestone; 67 7, Bellerophon bilobatus Sow., common; 678, same, side view; 679, Cyrtolites com- pressus Con. ; 680, 681, Cyrtolites (?) Trentonensis Con. ; species of Metoptoma, a genus which began in the Cambrian, Holopea, Trochonema, Eunema, Subulites, etc. Maclurea magna (Fig. 634) , Trenton of middle Tennessee (Safford) ; Chiton Canadensis B. is a Metoptoma, Black River limestone, Canada. (c) Pteropods. Pteropods were represented by the earliest known of the straight, slender shells called Tentaculites ; T. incurvus of Shumard is from Trenton beds in Missouri and T. Sterlingensis and Oswegoensis of M. & Worthen and T. Eichmondensis of Miller, from the Cincinnati group. There were also Conularise, and species of the Theca family. Fig. 682, Conularia Trentonensis H. ; Pterotheca attenuata H. ; Theca parviuscula H., Wisconsin ; Hyolithes, frequently having septa within in the smaller extremity. (d) Cephalopods. Fig. 683, Orthoceras junceum H. ; 0. anelhtm Conr., (Cycloceras anellum of Hyatt) ; 684, O. olorus H. ; 685, Actinoceras Bigsbyi of Bronn is Ormoceras tenuifllum of Hall, from the Black River limestone ; good specimens show a transverse row of foramina in each of the subdivisions of the beaded siphuncle, common in the Black River limestone ; Endoceras proteiforme H., Gonioceras anceps H. Endoceras (K^>CIJ, horn, and evdov, within) has a concentric structure of cone within cone in the siphuncle. Fig. 686, Cyrtoceras snbannulatum D'Orb. ; a, a transverse section; Fig. 687, Trocholites undatus Hyatt = Lituites undatus Hall, from the Black River limestone, referred to PALEOZOIC TIME LOWER SILURIAN. 515 Trochoceras of Barrande by Foord, and named T. Halli Emm. ; Fig. 688, Trocholites Ammonius Hall, from the Trenton, at Middleville, N.Y. Whiteaves has described and figured several species of the Orthoceras family from Manitoba, from the vicinity of Winnipeg Lake and elsewhere (1891). 7. Worms. Serpulites dissolutus B., Trenton, Canada; Salterella Billingsi Saff., Tennessee. 8. Crustaceans. Fig. 689, Asaphus platycephalus DeKay ; Fig. 690, Calymene calli- cephala Green ; Dalmanites (Phacops) callicephalus H. ; Fig. 691, Lichas Trentonensis Con.; L. cucullus M. & W., Illinois; Fig. 692, Trinucleus concentricus Eaton; Ceraurus pleurexanthemus Green ; Illcenus crassicauda Wahl. , New York and Illinois ; /. Taurus H. Other genera are Bathyurus, Triarthrus, Acidaspis, Encrinurus, Harpes, Proetus. Fig. 693, Leperditia f abilities Con., New York, Canada, and Tennessee; L. armata Wale. ; L. Canadensis Jones ; Beyrichia bella Wale., Trenton Falls. 9. Vertebrates. For Walcott's account of the discovery of the remains of Fishes in the Trenton of Colorado see Bull. Geol. 3oc., iii., 153, March 15, 1892. It was announced to the Biological Society of Washington, at a meeting, February 7, 1891. The remains were first found in the Harding sandstone, near Harding quarry, within a mile of Canon City. They also occur in Helena Canon, 18 miles to the north-northeast. The section at the latter place, above the Archaean gneiss, consists of 22' of arenaceous limestone with thin layers of chert, containing Upper Cambrian fossils ; 51' of a similar rock, with Cal- ciferous species, of the genera Ophileta, Straparollus, etc. ; 101' of sandstone the Hard- ing sandstone containing the plates of Placoderms and Lower Trenton fossils ; 110' of massive arenaceous limestone ; a thin band of Carboniferous limestone. The section is repeated many times in the canons, removing all doubt, says Walcott, as to the strati- graphic position of the Harding sandstone. There are no strata of the Upper Silurian or Devonian series at either of the localities. The characteristic species of the Galena limestone include Receptaculites Oweni H., Haly sites catenulatus, Lingulela lowensis Owen, Clitambonites Americanus Whitf., Mur- chisonia major H., Fusispira ventricosa H., F. elongata H., Maclurea cuneata Whitf., M. subrotunda Whitf. 2. Utica and Hudson Epochs. Figures representing the supposed terrestrial plants described by Lesquereux from the rocks of the Cincinnati group near Cincinnati, O., and Covington, Ky., are contained on page 198 of the last edition of this work. Dr. Newberry, after an examination of the specimens, published the same year his opinion against them. 1. Spongiozoans. Cyathophycus reticulatus Wale, and C. subsphericus Wale, from the Utica slate, Oneida County, N.Y. Trans. Albany Inst., x., 18, 1879. Species of Pasceolus, Astylospongia, Microspongia, Receptaculites, Brachiospongia. 2. Actinozoans. In the Hudson beds, Favistella stellata H., Fig. 704 ; several species of Columnaria ; Cyathophylloids of the genus Petraia, as in the Trenton ; also of the genus Zaphrentis, Z. Canadensis B. ; Halysites gracilis H., Fig. 705, from Green Bay, Wis. ; Sarcinula? obsoleta H., Fig. 706; Tetradium fibratum Saff., from Tennessee, etc., Figs. 707, 707 a T. cellulosum, the Birdseye species from Kentucky. 3. Hydrozoans. The species of Graptolites figured on page 510 are a few from the large numbers afforded by the Utica and Hudson shales. The specimens for figures 699, Cosnograptus gracilis, and 702, Dicranograptus ramosus, besides others, were from the Normanskill shales near Albany. The age of these shales has been questioned by Lap- worth on paleontological grounds (Trans. Hoy. Soc. Canada, iv., pages 167-172). The New York State geologists have considered the beds to be equivalent to the Hudson River, or the Utica shales, or to both. Lapworth refers the Graptolites to his " Ccenograptus zone " of Llandeilo age, equivalent to the Black River and Trenton limestones. The same beds 516 HISTORICAL GEOLOGY. at Cincinnati, holding Ccenograptus gracilis and three other species of Normanskill Grap- tolites, also contain Triarthrus Beckii and other characteristic Utica species (Ulrich, Am. GeoL, i.). 4. Echinoderms. Among Crinoids, Fig. 708, Glyptocrinus decadactylus H., not uncommon in New York, Ohio, Kentucky, and other states ; also Dendrocrinus Cin- cinnatiensis Meek, and species of the genera Heterocrinus, Porocrinus, Carabocrinus, Reteocrinus, Canistrocrinus, Stenocrinus, Ohiocrinus, locrinus, Anomalocrinus, Mero- crinus. Fig. 703 represents a large Star-fish from the blue limestone of Cincinnati, as figured by J. G. Anthony, the original of which was 4 inches across. There are also Cystoids of the genera Agelacrinites, Lichenocrinus, Hemicystites, all sessile species, and in this respect Actinia-like ; also Star-fishes of the genus Palceaster, etc. 5. Brachiopods. The figures of Brachiopods on page 507 are from specimens obtained in the Cincinnati beds. Other characteristic species are Lingula quadrata, Crania scabiosa, Zygospira modesta. 6. Mollusks. (a) Lamellibranchs. Cypricardites Sterlingensis M. & W. (6) Gastropods. Murchisonia Milleri H.; Cyrtolites ornatus Con., near Fig. 679 ; C. imbricatus M. & W., Illinois ; C. carinatus Miller and others ; Cyclonema bilix Con. ; C. Cincinnatiense Ulr., etc. ; Pleurotomaria Ohioensis H., etc. ; Cyclora parvula H. ; also species of the genera Trochonema, Helicotoma, Metoptoma, etc. (c) Pteropods. Species of Tentaculites, T. tenuistriatus M. & W., and T. Oswegoensis M. & W., from Illinois, in the Cincinnati group ; Theca parviuscula, H. ; Conularia for- mosa M. & D. ; C. Trentonensis H. (d) Cephalopods. Some of the species, besides those figured, are Orthoceras ampli- cameratum H. ; O. coralliferum (4 inches broad) ; 0. transversum Miller ; Gompho- ceras eos H. & Whitf., from Cincinnati; Actinoceras (Ormoceras) crebriseptum Hall; Endoceras proteiforme H. ; Trocholites Ammonius. 7. Crustaceans. Asaphus platycephalus ; A. Canadensis Chapm. Ostracoids occur of the genera Leperditia, Cytheropsis, Beyrichia, Primitia. Some of the genera and species from the Cincinnati beds are the following : Cceno- graptus gracilis H., Fig. 699 ; Dendrograptus gracillimus Lesq. ; D. tenuiramosus Wale. ; Dicranograptus ramosus H., Fig. 702 ; Diplograptus Whitfieldi H. ; D. spinulosus H. ; Climacograptus typicalis H. ; species of Zaphrentis ; Inocaulis arbuscula Ulv. ; the Tren- ton species, Glyptocrinus decadactylus; Heterocrinus Canadensis; H. geniculatus ; species of Palceaster, Protaster, Codaster ; of Lingula, Strophomena, Orthis, Rhyncho- nella, Crania ; Tellinomya alta ; Fig 709, Avicula demissa ; Ambonychia radiata ; species of Lyrodesma, Modiolopsis, Orthodesma; Conularia Trentonensis, C. formosa M. & D., Fusispira terebriformis, Endoceras proteiforme, Cyrtoceras ornatum ; Trinucleus concen- tricus, Calymene Christyi H., Dalmanites breviceps H., Proetus parviusculus H. ; species of Primitia, Beyrichia, Leperditia, Cytheropsis. In the Eureka district, Nevada, according to Walcott, the Pogonip limestone, which rests on the Cambrian and is 2700' thick, contains in the lower part a mixture of Potsdam and Silurian species ; the genera Dicellocephalus, Agnostus, Ptychoparia being largely devel- oped, and some species identical with Wisconsin Potsdam species ; and with these are Acrotreta gemma and some other Calciferous species ; but above the middle of the Pogo- nip beds the characteristic Cambrian features are absent, and there occur the genera Heceptaculites, Monticulipora, Pleurotomaria, Maclurea, Cyphaspis, Bathyurus and Asaphus ; and still higher the genera Orthis, Strophomena, Cyrtolites, Orthoceras, Endo- ceras, Tellinomya, Amphion, Ceraurus, Asaphus, Leperditia, Beyrichia, which appear to indicate the horizon of the Lower Trenton, or the Chazy. Between the Pogonip limestone and the Devonian there are 500' of Eureka quartzyte and 1800' of Lone Mountain lime- stone, and only Halysites catenulatus has been found here. See Walcott, U. S. G. 8. Hep., 4to, 1884. PALEOZOIC TIME LOWER SILURIAN. 517 720. The fossils discovered by A. Wing in the Taconic formation in the limestone of cen- tral Vermont were from many localities, and were more or less perfectly determined by Billings of Canada (Am. Jour. Sc., xiii., 1877). Some of them are Pleurotomaria stami- nea, Pleurocystites tenuiradiatus, Crinoidal disks, and large specimens of Maclurea from West Rutland ; Trinucleus concentricus from Hubbardton ; from East Cornwall, Ste- nopora fibrosa, S. Petropolitana, with species of Orthis, Strophomena, Rhynchonella, and Orthoceras, pronounced Trenton by Billings ; north and south of East Cornwall, Rhynchonella beds containing pygidia of Trilobites, a large Maclurea, Bathyurus Saffordi; at Bascom's Ledge, 3 miles west of south of West Cornwall, Asaphus canalis, Bathyu- rus conicus, Maclurea matutina, made Calciferous by Bil- lings ; east of Shoreham, Bathyurus extans, Columnaria alveolata, Trinucleus concentricus; in southern Bridport, Asaphus canalis, Bathyuri, Maclurea matutina ; in Orwell, Petraia profunda (?), Stenopora fibrosa, and 8. Petropo- litana, Heceptaculites Neptuni ; at Ellsworth Ledge, 2 to 3 miles west of Middlebury, a large Orthoceras, Bathyurus Saffordi, and from higher beds B. Angelini, Asaphus canalis, Maclurea, Orthis, Leperditia, Crinoidal stems; 2 miles north of Middlebury, the slightly curved Orthoceras, here figured, natural size, having 40 to 52 septa to an inch (1877); and half a mile to the northwest a large Maclurea. For an account of the discoveries of Dwight and others, see the references already given, page 495. The discoveries of Walcott were among the latest, and as they were made in the typical quartzyte of Vermont almost down to the Massachusetts line, also in the Eolian limestone just west, in Bennington, Vt., Williamstown, Mass., and in eastern New York, and in other localities in western Vermont and eastern New York, and thus covered all the Taconic formations, the demonstration became complete that the Taconic series is simply a combination of the Cambrian and Lower Silurian. EUROPEAN. The Lower Silurian series of Great Britain comprises, commencing below, the following groups : 1. The Arenig group (Sedgwick, 1852) : slates and flaggy sandstones which rest comformably on the Tremadoc slates of the Upper Cambrian. The beds occur in North and South Wales, and have a thickness of 2500 feet in the latter. The stiper stone beds of Shropshire are here included, and the upper part of the Skiddaw slates. In Merionethshire, North Wales, the volcanic rocks of this period include a lower series of ashes and con- glomerates, in some places 3300 feet thick ; a middle group of felstones and porphyries 1500 feet thick ; and an upper series of fragmental deposits 800 feet. 2. The Llandeilo flags : sandstones and shales of Llandeilo in Caermar- thenshire, Wales, where first described by Murchison (1834). In West- moreland and Cumberland, or the Lake District, the volcanic deposits of this period, but beginning in the Arenig and continuing through the Bala, Orthoceras primigenium ? 518 HISTORICAL GEOLOGY. cover an area of not less than 550 miles and have a thickness of about 8000 feet ; the rocks are felsytes, andesytic and other lavas, and volcanic tufa. 3. The Bala (Sedgwick, 1838), or Caradoc group (Murchison, 1839): con- sisting of shales, flags, and sandstones, with some limestone. The Caradoc rocks in Shropshire are about 4000 feet thick, while the Bala, in the Bala district, Merionethshire, have a thickness of only 1100 to 1200 feet, and the chief limestone stratum is only 20 or 30 feet thick near the middle. The Coniston limestone, the equivalent of the Bala, has a thickness of 200 feet. The Upper Coniston beds are Upper Silurian. In Caernarvonshire, northwestern Wales, great eruptions took place in this period, making eruptive accumulations 6000 to 8000 feet thick. The rocks are porphyries, felsytes, andesytes, besides diabases. Ireland, also, had its eruptions. 4. The Lower Llandovery group. The beds have a thickness in South Wales of 600 to 1000 feet, but they are absent from North Wales. They consist of shales, flags, sandstones, and conglomerates. The Upper Llando- very is closely related to the Lower in rocks and fossils. The two were separated, and the former made the base of the Upper Silurian, by Sedgwick in 1853, who called them the May Hill sandstones. This arrangement is adopted by Geikie. The thickness of the Lower Silurian rocks of Wales has been estimated at 25,000 feet. But over a fourth of this is owing to volcanic contributions, which, as they are of an extraordinary source, should be set aside in compar- ing the thickness of the sedimentary beds of different regions with reference to elapsed time. In the south of Scotland the thickness is over 16,000 feet. It is not possible to make out a precise parallelism between the British and American strata. Approximately the Arenig group represents the Cal- ciferous ; the Llandeilo flags, the Chazy; the Bala and Caradoc, the Trenton; and the Lower Llandovery, the Utica and Hudson beds. The Lower Silurian and Cambrian formations of Norway, Sweden, Russia, and Bohemia, which rest upon Archaean rocks, have but little thickness 1000 to 2000 feet ; and, adding what denudation may have carried away, 4000 or 5000 feet would be a large estimate for the original amount. In northern and northwestern France, or Normandy and Brittany, Lower Silurian rocks occur in a much upturned condition. The gr&s Armoricain is a sandstone, according to Barrois, of the age of the Chazy and Trenton limestones. Below it, and also above it, are shales or slates, and those above may represent the remainder of the Lower Silurian. They are found, also, of similar character in the Asturias, northern Spain, and in the Pyrenees. In Bohemia, the Lower Silurian of the basin of the Prague is the Stage D, or 2d Fauna, of Barrande. It consists of shales, with some quartzyte and conglomerate below, and has a thickness of about 3000 feet. In southern Sweden (Scania), the beds are mostly shales, many of the beds Graptolitic, with some limestone ; and are divided into a Lower, Middle, PALEOZOIC TIME LOWER SILURIAN. 519 721. and Upper Group; and the Christiania district, a Lower Group of Grapto- litic shales with sandstone, and an Upper, consisting largely of limestone with some shales. LIFE. PLANTS. The figure here given has great interest on account of its representing a specimen of a Lower Silurian plant above the level of a sea- weed. It is from the Skiddaw slates. A. Nicholson, the discoverer, described it as a seaweed (Buthotrephis Hark- nessi), and this it may still be. But Dawson refers it, with reason ap- parently, to the Marsileacese, at present fresh- water plants of the higher Cryptogams. As the group of leaves resembles the whorl on the stem of an Equisetum, he named the genus Protan- milaria, the name implying a relation to the genus Annularia of this tribe. ANIMALS. The following are figures of a few other fossils. Orthis jlabellulum(Fig. 722) occurs in the Bala limestone. Orthis elegantula (Fig. 723) ranges from the middle of the Lower Silurian (Coniston limestone) to the Wenlock of the Upper Silurian. The Crania (Fig. 724) is from the Bala. Asaphus Powisi (Fig. 726) and Ampyx nudus (Fig. 728) are Llandeilo Trilo- bites, and Illcenus Davisi (Fig. 727) occurs in the Bala limestone. Fig. 729 represents the telson or caudal segment and appendage of a large Ceratiocaris, C. Angelini, from the upper member of the Lower Silurian in 722-728. 726 Protannularia Harknessi. BRACHIOPODS. Fig. 722, Orthis flabellulum ; 723, O. elegantula; 724, Crania divaricata. LAMELLIBBAJSCH. 725, Conocardiuin dipterum. TRILOBITES. 726, Asaphus Powisi ; 727, Illsenus Davisi ; 728, Ampyx nudus. Sweden. The length of this Crustacean in its entire state must have been fully one foot. 520 HISTORICAL GEOLOGY. The earliest of known fossil insects is from Graptolitic slates in the upper part of the Lower Silurian of southern Sweden. It is a Hemipter, and is named by Moberg Protocimex Siluricus (1892). 729. Telson of Ceratiocaris Angelini, nat. size. Jones and Woodward, '88. Characteristic Species. Great Britain. Arenig group. The Skiddaw slates of the Arenig group abound in Graptolites of the genera Diplograptus, Climacograptus, Didymograptus, Phyllograptus, Dendrograptus, etc. Other prominent genera and species of the group are : Orthis calli- gramma, Obolella plicata, Lingulella Davisi; Pleurotomaria, Ophileta, Raphistoma ; Bellerophon, Conularia Homfrayi, Orthoceras; Agnostus, ^Eglina grandis, Ogygia, Asaphus Homfrayi, Ampyx Salteri; also the new genera Trinucleus, Ulcenus, Barrandia, Calymene, Phacops, Placoparia, Homolonotus. Llandeilo flags and Lower Bala. Graptolites of the same genera as in the Arenig; also Halysites catenulatus, Monticulipora favulosa, Favosites fibrosus ; Actinocrinus, Echinosphcerites, Crlyptocrinus, Palceaster ; Acrotreta, Crania, Leptcena, Strophomena, JKhynchonella ; Modiolopsis, Ctenodonta, Palcearca, Pleurorhynchus (Conocardium), Ophileta compacta, Murchisonia bellicincta, Euomphalus, Loxonema, Pleurotomaria; Orthoceras, Endoceras, Piloceras ; Ogygia Buchii, Asaphus tyrannus, A. Powisi, Ampyx nudus, Barrandia, Trinucleus, Acidaspis Jamesii, Lichas, Ulcenus, Homalonotus, Cheiru- rus, Phacops, Calymene Blumenbachii, ^Eglina mirabilis. Bala beds, Caradoc sandstone, and Coniston limestone. Monticulipora frondosa M., Favosites fibrosus, Heliolites-interstinctus, Halysites catenulatus, Cyathophyllum, Petraia ; Leptcena rhomboidalis, Orthis biforata, O. calligramma, O. flabellulum, O.porcata, 0. elegantula, Atrypa imbricata, Leptcena (Plectambonites) sericea, Crania divaricata ; Murchisonia, Holopella, Trochonema, Raphistoma, Cyclonema, Bellerophon bilobatus, B. nodosus, B. carinatus (which three species occur also in the Lower and Upper Lland- overy) ; Orthoceras vagans, 0. annulatum, O. Barrandii (the three continuing into the Lower Llandovery) ; Endoceras, Lituites, Cyrtoceras, Trocholites, Piloceras; Ulcenus, Phacops, Cheirurus, Lichas, Acidaspis, Ampyx, Agnostus, Harpes, Remopleurides, Caly- mene Blumenbachii, C. Allportiana, Sphcerexochus mirus. Lower Llandovery group. Favosites fibrosus, Halysites catenulatus, Heliolites inter- stinctus, Petraia bina, Orthis Bouchardi, Atrypa, Meristella subundata, StricTclandinia lens, Ehynchonella tripartita, Spirifer plicatellus, 8. exporrectus, Strophomena arenacea, Pentamerus oblongus, P. undatus, P. globosus (the three occurring in the Lower and Upper Llandovery) ; Ulcenus Bowmani, Cheirurus bimucronatus, Trinucleus concen- tricus, Proetus Girvanensis. Lower Silurian beds occur in the south of Scotland, and also in the northwest Highlands. But in the latter region there is a striking resemblance in fossils, as pointed out by Salter, to forms in Canada and New York the species includ- ing Orthoceras arcuoliratum, Orthis striatula, Ophileta compacta, Murchisonia gracilis, M. bellicincta, and also species of Maclurea, Eaphistoma, and others of American type. Moreover, at the same time, the species of northwestern Scotland differed from those of England and Wales. From these facts it is evident that troughs with Archaean confines had the same importance on the British or European border of the Atlantic as on the North American side. We may conclude also that the barrier between northwestern Scot- PALEOZOIC TIME LOWER SILURIAN. 521 land and the areas to the south and southeast, which could have made its fauna more American than British, must have had great length. According to Etheridge, the Lower Silurian of Great Britain, up to 1885, had afforded 161 species of Hydrozoans, 47 of Actinozoans, 5 of Crinoids, 23 of Cystoids, 6 of Asterioids, 174 of Brachiopods, 18 of Bryo- zoans, 80 of Lamellibranchs, 19 of Pteropods, 67 of Gastropods, 21 of Heteropods, 66 of Cephalopods, 188 of Trilobites, 31 of Entomostracan and Phyllopod Crustaceans; no Eurypterids, no Insects, no Fishes. Scandinavia and Russia adjoining. The area of metamorphic mostly Archaean rocks covers, besides the Scandinavian peninsula, the country to and including the White Sea and thence southwest to the Gulf of Finland, thus inclosing entirely the Gulf of Bothnia. The Cambro-Silurian borders this region at the North Cape ; also north of St. Petersburg and south of this place westward along the south side of the Gulf of Fin- land to the Swedish islands of Gotland and Oland in the Baltic, and the adjoining east coast of Sweden. Then, over the interior of Scandinavia, there is a large area on the west side of the mountains from above Trondhjem to the shores south of Bergen ; and east of the mountains about Ostersund and Christiania, and also at some other points. The beds have in general a thickness of from 1000' to 2000'. There are in Finland, Stage B (the first) , Graptolitic beds containing Lingula, Siphonotreta, Obolus, the limestones contain- ing Megalaspis, Orthis (O. parva}, Orthoceras, Porambonites, Asaphus, Ceraurus, Ampyx, Phacops; in Stage C, Echinosphcerites, Orthoceras; and above, Orthis (O. lynx}, Poram- bonites, Pleurotomaria, Ceraurus, Phacops ; Stage D, with Strophomena, Lichas, Ceraurus, Phacops ( Chasmops) Stage E, with Leptcena (L. sericed), Strophomena (S. deltoidea), Orthis (O. testudinaria~) , Phacops, Encrinurus, Cybele; Stage F, with Orthis, Strophomena (S. expansa}, Bellerophon (B. bilobatus}, Phacops, Ceraurus, Encrinurus. France. The Armorican sandstone of Brittany afforded Lebesconte and Barrois: 3 Trilobites ; only 4 Brachiopods, and those of the Lingula family ; over 30 Lamellibranchs, a Bucania, and 3 Ceratiocarids, but a poor representation of the fauna of the period, because of the impurity in the waters which a sandstone formation indicates. Barrois refers the beds to the age of the Chazy and Trenton limestones of the United States. The Ceratiocarids include: Ceratiocaris, Myocaris lutsaria Salter and Trigonocaris Lebes- contei Barrois. The Lower Silurian rocks of Portugal have afforded a very large Trilo- bite of the genus Lichas. It is named Lichas ( Uralichas) Eibeiroi. The total length is estimated to be 560 mm., and 385 mm. without the caudal spine, which is 175 mm. long. (Corara. des Trav. Geol. du Portugal, Fauna Silurica, Lisbon, 1892.) This is the longest Trilobite described; it exceeds 2 feet in length. Paradoxides regina, described by Matthew from the Cambrian of New Brunswick, was estimated to have a total length of 450 mm. Bohemia. The Lower Silurian of Bohemia is divided by Barrande into 5 sections. They afford Trilobites of the following genera. (The numbers in parentheses show in which of the 5 sections they occur ; and the and + , that the genus had species also in preceding or later time.) Agnostus (+ 1, 5), Acidaspis (1 to 5+), ^Eglina (1 to 5), Amphion (1), Ampyx (5 + *),Areia (2, 5), Arethusina (4 -f ), Asaphus (1 to 5), Barrandia (1), Bohemilla (1), Calymene (1 to 5 +), Carmon (1, 5), Ceraurus (1 to 5 +), Cyphaspis (6 -f ), Dalmanites (1 to 5), Dindymine (1 to 5), Dionide (1, 3, 5), Harpes (1 + ), Har- pides (1), Homalonotus (2 to 5), lUcenus (1 to 5+), Lichas (1, 5+), Ogygia (1, 5), Phacops (4, 5-f), Phillipsia (5), Placoparia (1, 2), Proetus (1, 5+), Remopleurides (5), Sphcerexochus (5 +), Telephus (4, 5), Trinucleus (1 to 5), Triopus (2). In Asia, Silurian beds of the Tibetan Himalayas, described by Salter and Blanford, have a thickness of 6000', and afford species of Heliolites, Ptilodictya; Leptcena, Stro- phomena, Orthis, Ctenodonta; Holopea, Cyclonema, Trochonema, Raphistoma, Pleuro- tomaria, Murchisonia, Bellerophon, Theca; Orthoceras, Cyrtoceras, Lituites ; Calymene, Sphosrexochus, Lichas, Ceraurus, fllcenus, Asaphus, but no American or European species. 522 HISTORICAL GEOLOGY. From western China, Richthofen has reported Orthis calligramma, Leptcena (Plectam- bonites} sericea, Spirifer radiatus, Atrypa reticularis, Favosites fibrosus, Heliolites inter- stinctus, Haly sites catenulatus, etc. In southern Australia, in Victoria, Lower Silurian beds, made 35,000' thick by Mr. Selwyn, have afforded various Graptolites of the common Lower Silurian genera. ECONOMICAL PRODUCTS OP THE LOWER SILURIAN FORMATIONS. Lead Ore, Galena. The Galena limestone of Wisconsin and the adjoin- ing states on the south and west derives its name from the valuable lead deposits which it contains. Similar deposits occnr in the Lower Silurian limestones of Missouri (though not at present profitable like those of the Cam- brian and Subcarboniferous limestones of that state) and also in Arkansas. The large Joplin mines of Missouri are in the Subcarboniferous. On these deposits see under " Veins/' page 342. None of them, as there stated, are of Lower Silurian origin, but of some later, unascertained date. Mineral Oil and Gas. Mineral oil and gas come from the decomposition of animal or vegetable materials, when buried and under close confinement from the atmosphere. The Trenton limestone and the Utica and Hudson shales have long been known to afford mineral oil, especially since the early reports on the subject by T. S. Hunt, who rightly referred these substances to organic materials buried in the limestone or shale at the time of their formation (1861, 1866). The black color of the Utica shale is due to car- bonaceous substances, and oil is easily obtained by heating ; and in Colling- wood, Canada, there were formerly works for the purpose, 30 to 36 tons of shale yielding 250 gallons of crude oil (at a cost of about 14 cents per gallon) an amount corresponding to about 3 per cent of the rock (Hunt). At Manitoulin Islands, also, petroleum was early procured by boring. Whitney obtained 21 per cent from the shale of Savannah, 111. ; 11 to 16 per cent from that of Dubuque ; and 12 to 14 per cent from that of Herkimer County, N.Y. The oil has been found in Orthocerata at Pakenham, Canada, and in fossil Corals at Watertown, N.Y. The distillation process was long since thrown aside in consequence of the free supplies of the liquid oil through Artesian borings ; and among the productive rocks are some of the Lower Silurian. The idea, now fully sub- stantiated, that the oil and gas are usually to be obtained along anticlinals, was announced in 1861 by T. S. Hunt, and independently by E. B. Andrews. In Ohio and eastern Indiana the Trenton limestone affords both oil and gas abundantly, but chiefly the latter. The region is within the underground range of the Cincinnati anticline, and the principal Ohio localities are at and near Findlay, 150 miles north of Cincinnati, on the axial part of a portion of the anticline, where it has a local upward bulge or bend; and to this upward bulge in the axis the Findlay region appears to owe its gas-confining power. The borings descend 1100 to 1200 feet to the Trenton limestone, and only 15 to 25 feet, or, in some parts, 50 feet, into the rock, a greater depth usually being only sparingly productive. The Findlay wells yielded, in 1886, PALEOZOIC TIME LOWER SILURIAN. 523 at the rate of 20 to 25 millions of cubic feet of gas per day, and half the whole amount came from a single well, the Karg well. One boring in the vicinity, at Bairdstown, yielded 4,000,000 cubic feet per day when 9 feet down in the limestone, and 12,400,000 when 17 feet down; and the tools " refused to descend deeper, dancing in the well like rubber balls." (Orton, Rep. Econ. G. Ohio, 1888.) The rock pressure in some parts has been found to equal 650 pounds to the square inch : in the Findlay field it is about 450 pounds ; in the Indiana field about 320 pounds. Owing to the pressure, the gas, as it is confined in the Trenton limestone, is greatly condensed, its volume, if the pressure equals 320 pounds to the square inch, being about J-th of that after escape. The productive limestone, as stated by Orton, is in all cases dolomyte. In the Findlay region the composition was found to vary from a ratio, for the calcium and magnesium, of 1 : 1 to that of 2 : 1. The marsh conditions under which dolomyte is formed are favorable for the gentle trituration or mace- ration of organic materials, and their inclusion in the deposits so made. It is found, also, by Professor Orton, that the limestone is porous, and is thus enabled to contain the oil or gas. Since the conversion of calcyte to dolomyte causes a diminution in bulk of ^ to ^ (page 134), the pores, which are a result of the change, should give the rock great containing capacity equal, says Orton, to the actual amount afforded. The amount of marsh gas (ordinary illuminating gas) in the mineral gas of Findlay is about 92-5 per cent ; and with this are 2 per cent of hydro- gen, 0-3 of olefiant gas, 3-5 t>f nitrogen, and about 0-5 per cent each, of oxy- gen, carbonic acid, and carbonic oxide, and 0-2 of hydrogen sulphide. In the region of Lima, Ohio, the limestone yields oil. Salt water, also, comes up in some borings. In the borings water is excluded by tubing. The pro- duction of the wells is often greatly increased by lowering torpedoes con- taining from 20 to 160 quarts of nitro-glycerine to the bottom of the well and exploding them by means of a piece of iron called a " go-devil," which is dropped down the hole and strikes a fulminating cap on the torpedo. The whole process is termed " shooting " a well. The explosion shatters the rock and opens fissures. Thus the area of supply is extended and the yield of oil or gas increased. In Indiana the natural gas territory adjoins the eastern, or Ohio, boundary for about 65 miles, and has an average width of 50 miles. The porous layer, according to A. J. Phinney, is 1 to 20 feet thick, and lies beneath a non-porous outer layer of the limestone, 1 to 15 feet thick ; and the rock is sometimes so open-textured that air may be freely blown through it, and it will absorb -^ or even 1 of its weight of water. In 1890, the aggregate daily flow of the Indiana gas wells was 779,525,000 cubic feet. (Phinney, U. S. G. S. Rep.) The Trenton limestone has afforded no gas or oil in Kentucky or Pennsylvania. Marbles. The Chazy affords black marble in the vicinity of Lake Cham- plain. The Taconic crystalline limestone yields white and clouded statuary 524 HISTORICAL GEOLOGY. and ornamental marble in West Rutland, Dorset, Pittsford, etc., Vt. ; archi- tectural marble in Lee, Mass., Canaan, Conn., Westchester County, N.Y., and in Pennsylvania ; the Trenton, a beautiful mottled brown and reddish brown marble in east Tennessee in Hawkins County and Knox County ; the lighter spots in it are delicate Corals (Monticulipora, Stenopora, etc.). Iron ore. The valuable iron ore, limonite, occurs in great beds along the junction of the Lower Silurian limestone and the overlying Hudson shales in all the states on the line from Vermont to Alabama, and in many places it is worked for the iron. But the ore is a result of the decomposition of the rocks long subsequent to the Lower Silurian era (page 126). GENERAL OBSERVATIONS ON THE LOWER SILURIAN. ROCKS. It is a point to be noted that, during the Lower Silurian, the rocks of the Continental Interior over the Mississippi Basin were chiefly limestones; and that in the Trenton period the limestones extended in great force to and beyond the Appalachian protaxis. There is no evidence of their origin at abyssal depths. The beds were mostly made in clear waters near the sur- face, as in modern coral seas, and at moderate depths, probably not exceeding a few hundred feet. Magnesian limestones prevail below the Trenton, and occur to some extent within this formation; and such limestones (dolo- mytes) are strong evidence of a sea-marsh condition during their origin, or of shallow sea-border flats, as explained on page 133. Such an origin also explains that fine trituration of all the calcareous relics, which made the magnesian limestone so generally unfossiliferous. CLIMATE. No proof that a marked diversity of zones of climate prevailed over the globe is observable in the fossils of the Cambrian period, or of any part of the Lower Silurian era, so far as yet studied. The difference between the polar regions and the parallel of 40 was probably not greater than between cold temperate and warm temperate. It has been inferred that some differ- ence in zonal temperature exists from the closer resemblance of fossils of northwestern Scotland to those of Canada (page 572) than to those of Eng- land, and the existence of the Gulf Stream of the Cambrian Atlantic is sug- gested by G-. F. Matthew. The following species, common in the United States, and occurring at least as far south as Tennessee, have been found in the strata near Lake Winnipeg: Strophomena (Rafinesquina) alternata, Lep- tcena (Plectambonites) sericea (?), Maclurea magna, Raphistoma lenticulare, Calymene callicephala, Monticulipora lycoperdon, Receptaculites Neptuni. The mild temperature of the Arctic waters is evident from the occurrence of the following species on King William's Island, North Devon, and at Depot Bay, in Bellot's Strait (lat. 72, long. 94) : Monticulipora lycoper- don, Orthoceras moniliforme H., Receptaculites Neptuni De France, Actino- PALEOZOIC TIME LOWER SILURIAN. 525 ceras crebriseptum H., besides Maclurea arctica Haughton, a species near M. magna of the Chazy. Moreover, the formation of thick strata of limestone shows that life like that of the lower latitudes not only existed there, but nourished in profusion. BIOLOGICAL PROGRESS. 1. General Progress. During the Lower Silurian era progress in animal life was marvelously great. Before it closed, nearly all the grander divisions of marine invertebrates were represented. And these grand divisions were displayed under nearly all their subdivisions. The Actinozoans were repre- sented by Alcyonoids and Madreporids, as well as by Cyathophylloids ; La- mellibranchs, by Monomyaries, related to the modern Avicula and Pecten ; Heteromyaries, related to Modiola and Mytilus ; Dimyaries, both of the Integripallial section related to Area and Nucula, and of the Sinupallial section related to Cypricardia and Tellina; Pteropods, by more types and much larger species than now exist; Gastropods, by the species of the Trochus and Pleurotomaria types ; Trilobites, by many new genera ; and in addition there were Eurypterids of large size. Besides all these, there were Fishes, the first of Vertebrates. The chief divisions of marine Invertebrates supposed to be absent are : Crustaceans above Entomostracans, that is, the typical Tetradecapods and Decapods ; the Dibranchs, or Squids and Cuttles, among Cephalopods ; the Echinoids among Echinoderms, and the Actinoids, or modern type of Corals, among the Actinozoans. The exhibition of marine Invertebrates was, therefore, very wide in range and far advanced in grade. There was diversity enough to have afforded material for quite a full work on Inverte- brate zoology. But, in addition to life in the waters, there was already life over the land, and life, also, that could fly, and so bring the air above the land into new service. The water-margins and moist places of the growing continents were green with acrogenous plants that gave promise of future forests. Insects, as the one specimen reported proves, were common almost every- where. Hemipters are the so-called "Bugs" and Aphides. They are incomplete in metamorphosis, like other low-grade Insects, and, therefore, are a kind that might be among the earliest in geological time ; but until the discovery in 1892, no fossil Paleozoic species had been reported. It has already been remarked that terrestrial animal species rarely become fossil- ized; among the rarer of these are Insects, and of the rarest are Myriapods and Spiders, and those Insects that do not frequent water-margins. Myria- pods were probably part of the terrestrial population, and perhaps, but less probably, Spiders. 2. Culmination of the types of Graptolites, Cystoids, Pteropods, Trilobites, and Ostracoids. The Graptolite, Cystoid, Pteropod, Trilobite, and Ostracoid types appear to have reached, in the Lower Silurian era, and passed, their time of highest display. 526 HISTORICAL GEOLOGY. Barrande, in his review of the Trilobite Fauna of the Paleozoic, which he published in 1871, made the total number of Cambrian and Silurian species then known 1500 ; and those subsequently introduced, in the Devo- nian and Carboniferous eras, about 200. He states that in the Cambrian period the number of species known was 252 in 28 genera ; in the Lower Silurian, 886 species in 52 genera, eight of these genera being of Cam- brian origin; then in the Upper Silurian his third Fauna there were 482 species in 20 genera, but only three of these 20 genera were of Upper Silurian origin, the rest already existing in the Lower Silurian. The number of known Cambrian species of Trilobites has been increased since 1871 by more than 200 ; and besides, a larger number of the genera are now known to date from the Cambrian. But still Barrande's conclusion remains right that the Lower Silurian was the era of maximum develop- ment of Trilobites. In North America, the Lower Silurian beds add 215 species and 30 genera of Trilobites ; the Upper Silurian only 81 species and three genera ; and of these three, two occur in Europe. The type for awhile was the highest of the seas ; but that of Cephalopods, of later introduction, had passed it in size, grade, and power before the Lower Silurian era closed. Such facts give strong characteristics to the Lower Silurian, and exhibit its contrast to the Upper. The Hydrozoans, Actinozoans, and Bryozoans, which usually produce, by multiplication, compound groups of branching and other forms, and show thereby their low grade among species, are rare fossils in the Cambrian as simple individuals, and are wholly unknown in compound groups, although such groups are indicative of low grade, and the Bryozoans are the lowest of the Molluscoids. But in the Lower Silurian era the compound forms after the commencement of the Chazy period were common, and were emi- nently so during the Trenton period. Ulrich states, after an investigation of the Bryozoans of Minnesota (a few of his figures are reproduced on page 506), that the contributions from them of calcareous material for the Lower Silurian limestones of that state were twice as great as those from the Brachiopods (Rep. L. Sil Bry. Minnesota, 1893). UPTURNINGS AT THE CLOSE OF THE LOWER SILURIAN. AMERICAN. General quiet of the Lower Silurian era. The strata of the Lower Silu- rian in eastern North America appear to have been laid down, one over the other, without intervening dislocations. Through the era there were extensive oscillations in the water level, for this is indicated by the varying limits of the formations, as well as by changes in the kinds of rocks ; and the exposed beds of one period probably suffered much by denudation before the next were deposited. But these oscillations resulted in no great upturn- ings of the rocks. The era was one of quiet progress in sedimentary PALEOZOIC TIME LOWER SILURIAN. 52J deposition from the beginning of the Cambrian to the close of the Lower Silurian; and it was a very long era, possibly as long as all time that has since elapsed. Mountain-making finally ensued, producing, among its effects, the Taconic Mountain Range along western and northwestern New England, and also the Cincinnati geanticline, besides uplifts in Nova Scotia and New Brunswick. Moreover, there is probable evidence that the Taconic Range at the north was but one of a series along the Atlantic border. The Taconic Range and system. Some account of the Taconic Range has been given on pages 386, 387. There were great flexures, great faults, and general metamorphism. Fig. 730 represents a section, by Selwyn, extending, near Quebec, from Montmorenci Falls on the northwest and crossing the north channel of the St. Lawrence to Orleans Island. 730. N.W. II III S.E. Faulted and plicated rocks from Montmorenci Falls to the island of Orleans and beyond. Vertical scale, 500 feet = 1 inch ; horizontal scale, 1 miles = 1 inch. Selwyn. The falls are to the left at F, and I marks the line of one fault. To the left of this fault-line are Archaean rocks overlaid horizontally by 50 feet of Trenton limestone. To the right of it there are Lower Silurian rocks, in a plicated condition, from the Calciferous and Chazy (Quebec group, /, /, /) at the bottom, through the Trenton limestone (a, a, a) to the Utica and Hudson shales (c, c, c), the upper of these rocks making the bottom of the north channel of the river. To the right, at II, there is a second fault, the main fracture ; and at III, a third fault. Between the two is Orleans Island, the beds numbered 6 containing Utica G-raptolites ; and 1 to 5, those of the so- called Levis formations of the Quebec group of the age of the Calciferous and Chazy. From this region faults continue in a south-by-west direction, through Vermont and eastern New York. They are conspicuous in Vermont, at Snake Mountain, in Addison County, and also south of Shoreham, where the red sandrock rests on Hudson shales (Wing) ; and in New York at Bald Mountain, and elsewhere in Washington County, near Rhinebeck on the Hudson, and in Dutchess County ; and also in New Jersey, a mile west of Otisville, and at the Lehigh Water Gap (G. H. Cook). Fig. 731 represents the fault at Snake Mountain, as given by A. Wing (1877). To the right of F is the south end of the ridge of Cambrian red sandrock, called Snake Mountain ; to the left are Lower Silurian formations 528 HISTORICAL GEOLOGY. in an overthrust flexure, with the Hudson slates (d) lying in the syncline. The fault extends for many miles to the north and south. 731. a b a FAULT AT SNAKE MOUNTAIN, VT. F, fault ; a, Trenton limestone ; 6, Chazy limestone ; c, Cambrian ; d, Hud- son shales. A. Wing. The great western fault of eastern New York, as described by Walcott, enters New York from Vermont in Hampton, Washington County, and extends south- south west to the Rensselaer County boundary line, passing through Argyle to Bald Mountain in Greenwich and beyond. In the fault, as in those of Vermont, the Lower Cambrian strata are upthrust westward over the Silurian. Fig. 732 represents a section of Bald Mountain, as viewed from the south. According to it the plane of the fault dips at the low angle 732. Section of Bald Mountain, the profile as seen from the south. Ch, Chazy limestone ; E, Calciferous ; X, 8, shales. Walcott. of 25. To the right are the Cambrian beds, and to the left, the underlying Chazy and Calciferous, and in other localities the Trenton and Hudson for- mations. Another similar fault, of like westward thrust, and on a nearly parallel line, lies three to four miles farther eastward ; and a third, still more to the eastward. The amount of displacement at Bald Mountain is stated to be between two and three miles. For a map of the Taconic limestone belts, as now existing in part of eastern New York and the associated schists and quartzytes of western Massachusetts and Connecticut, reference may be made to a description of the region in the author's papers of 1880, 1881, and 1885, 1887. The chief belts lie to the west of the Green Mountain Archaean protaxis, and continue west of it into eastern New York, and also, after an interruption, in belts that cross Hudson River into New Jersey and beyond. The largest belt is that of Eolian limestone (or marble) of Vermont, and the Stockbridge lime- stone of Berkshire, Mass, (so named by E. Hitchcock), lying to the eastward of the main Taconic Ridge. It passes by the east side of Mount Washing- PALEOZOIC TIME LOWER, SILURIAN. 733. 529 LIMESTONE AREAS OF DUTCH ESS WESTCH ESTER AND PUTNAM COUNTIES NEW YORK AN DOT PART OF WESTERN CONNECTICUT WITH THE ARCH/EAN or PUTNAM CO. AND THE PALISADE TRAP RANGE, .... 5 , . 10 M. a Limestone X~ Archaean &k Palisade Trap 'S MANUAL 34 530 HISTORICAL GEOLOGY. ton, in southwestern Massachusetts, into Canaan and Salisbury in north- western Connecticut. The accompanying map (Fig. 733) illustrates the character and positions of the belts of limestone (horizontally lined areas), which extend southward in eastern New York and from Canaan and Salisbury in Connecticut. The area covered with V symbols is mainly Archaean. It is a continuation of the New Jersey Highlands (a part of the protaxis) ; it crosses the Hudson, between Peekskill and Fishkill, N.Y. West of the Kent Belt of lime- stone there is an area of gneiss and other schists and some limestone of Archaean age, between borders of Taconic schists and quartzyte. The cross- lined area, west of the Hudson, is the Palisade belt of trap. At the northeast corner of the map, in Canaan (a town lying mostly to the north of the northern limit of the map), the southern part of the great Stockbridge belt divides. The chief branch extends southwestward into eastern New York, and then southward to Dykemans, where it ends against the Archaean, after an interval of mica schist. Just west of the Taconic Eidge are other belts of limestone. The first of these is a western portion of the limestone belt of Stockbridge and West Stockbridge ; for the limestone east of the Taconic Ridge dips under the schist of the mountain, and comes again to the surface, through a synclinal flexure ; the character of the syn- cline is illustrated for the Mount Washington region, in Fig. 103, page 105. In further illustration of the synclines of the Taconic Range, Figs. 734, 735 are here introduced. Fig. 734 represents the general structure of Grey- 734. Taconic synclinal mountains of crystalline limestone overlaid by mica or hydromica schist. Fig. 734, Greylock, Emmons. 735, Mount Eolus in Dorset, Vt. Hitchcock. lock, the Taconic Mountain of northwestern Massachusetts (the blocked areas are limestone) ; and Fig. 735, Mount Eolus, Vt., a different phase of the syncline, in which the mountain consists mainly of limestone. All the western belts of limestone have similar relations to the schists. On the map they are shown to extend southwestward, with one or two interruptions, into and through Dutchess County, N.Y., and to and beyond the Hudson River, as above stated. The other narrower branch, which begins in southern Canaan (just beyond the north border of the map), as shown by Percival, extends southward, and passes Kent. Farther eastward, there is still another outcrop of this same limestone, owing to a syncline, in a belt that passes by New Milford. Southward from the extremities of these two belts (see the map) a series of smaller limestone belts is continued through Westchester County, N.Y., PALEOZOIC TIME LOWER SILURIAN. 531 into New York (or Manhattan) Island. The limestone, which is everywhere crystalline, or is a marble, contains abundantly the same accessory minerals in southern Massachusetts and Connecticut, as in Westchester County and New York Island ; namely, tremolite and white pyroxene. In this respect the Taconic limestone is widely different from the Archaean limestones of the protaxis in Massachusetts, and of outcrops in the Kent-Cornwall Kidge, west of Kent, these being chondroditic (p. 67). Two of the Westchester belts, near Peekskill, extend northward up the Archaean Highlands of Putnam County. They lie in what were originally valley-depressions in the Archaean, although not valleys now. Their beds are much upturned, although confined so closely by the Archaean ; and they are metamorphic, but of the lighter kind characterizing the corresponding beds on the north border of Peekskill. To produce the upturning, the inclosing Archaean rocks must have been thrust forward either along frac- tures, or molecularly. The metamorphism apparently indicates that the beds once had great thickness over this part of the Highlands. The Taconic series of rocks, and series of upturnings, appear therefore to extend all the way from the St. Lawrence valley to New York City. They are situated mostly to the west of the Archaean protaxis ; but, in Canaan, the more eastern branch, described above, passes to the eastward of it, leaving part of the Archaean area on the west ; and it is this eastern branch that continues on through Westchester County. The east and west positions of part of the limestone belts of Westchester County, just south of the Archaean of Putnam County, indicate that, in the upturning, the schists and other Taconic rocks were forced up against the essentially stable Archaean area. The T-shaped symbols on the map indicate the strike and dip of the rocks, and show that the limestone and schists, referred to the Taconic series, are conform- able in strike. The Taconic upturning is known to have occurred not later than the close of the Lower Silurian era from the fact that Upper Silurian rocks are not present in the series, but actually overlie the Lower unconformably in some localities; as at Becrafts Mountain, near Hudson, N. Y. ; on St. Helens Island and Beloeil Mountain, near Montreal, where the Lower Helderberg beds cover unconformably Lower Silurian slates ; and near Lake Memphremagog, where the Niagara limestone occurs with its characteristic fossils, and also beds of Devonian Corals. Again, on the eastern side of the Green Mountains, in the Connecticut valley, there are unconformable Devonian beds at Bernardston, Mass., and Upper Silurian at Littleton, N.H. The earlier of the formations of the Upper Silurian are very thin in the eastern part of the state of New York, and this is apparently owing to the previous emergence of the Green Mountain area, shallowing the waters to the eastward. The schists, which are argillyte and hydromica schist in Vermont, are mica schist, chlorite schist, and gneiss in Massachusetts, and coarser mica schist and gneiss in West- Chester County. The probability that the upturning was continued southward through 532 HISTORICAL GEOLOGY. 736. Virginia has been sustained by the discovery, in 1892, of Crinoids, by N. H. Darton, in the slate quarries of Arvon, Buckingham County, Va. A figure of one of the species is here given from Darton's paper. Walcott states that the species are allied to those of the genera Schizocrinus, Heterocrinus, and Poteriocrinus, and are of either Trenton or Hudson age. It will be seen on a map that the Westchester belt and the Buckingham County locality are so related in position that the latter may have been a part of a long Westchester Taconic Eange, which passed just west of Philadelphia and Baltimore, and may have included South Mountain, Pa., and other ridges beyond, to the east of the protaxis, the Appalachian Range being to the west of the same. This would make the Taconic Range of western New Eng- land one in a great Taconic system of mountain ranges. Eruptive rocks. Rocks that came up melted, probably at the time of the Taconic disturbance, exist south of Peekskill, N.Y., spread widely over much of Cortland County, and also occur on Stony Point on the opposite (west) side of the Hudson River. The rocks cut through Lower Silurian limestones, and hence are not from the crystalline dates of f n ejection; but they may be. of much Buckingham County, Va. Darton, '92. J J J later origin. They are rocks of unusual kinds, being noryte, chrysolitic hornblendyte and pyroxenyte, coarse dioryte, and a granite-like rock in which the feldspar is oligoclase. The rocks were described by the author in 1880, 1881, and by G-. H. Williams in 1886. The long strips of schist and limestone in the igneous rocks appear to prove, as the author stated in his paper, that these eruptive rocks are partly or wholly metamorphic-igneous, produced by the fusion of Cambrian or Lower Silurian rocks during the period of upturning and metamorphism. A dike cutting through the Hudson beds of the Blue Mountains, of west New Jersey, near Beemerville, is probably of the same age. The Beemerville rock also is a rare kind an Elseolite-syenyte (B. K. Emerson, 1882). Many "trap dikes" cut through the Taconic formation in the vicinity of Lake Champlain which may be of cotemporaneous origin (Kemp and Masters, 1893). The Cincinnati geanticline. Cotemporaneously with the disturbances above described the low geanticline was formed, called the Cincinnati uplift (page 537), making two islands, one over part of Ohio, eastern Indiana and Kentucky, and the other over Tennessee, as reported by Safford, Newberry, and Orton. The general course of the upward bend of the crust was north- PALEOZOIC TIME LOWEK SILURIAN. 533 easterly, nearly parallel with the Appalachians. But at the north, in Ohio, it extends northwesterly, and has also a northeastern branch in the direction of Findlay, Ohio, toward Lake Erie. That this was the time of the uplift is proved by the absence of Upper Silurian and Lower Devonian beds over the region, these formations thinning out toward the axis, where the Cincinnati limestone is the surface rock ; and, in Tennessee, as Safford states, by the Devonian black slate resting directly on the Lower Silurian beds. The line of the axis presents now no conspicuous topographical feature; but the direction of the draining streams, which follow the strike of the strata on either side, indicates that it once formed a watershed that gave the initial bearing to their flow. The part of the arch about Cincinnati has been more deeply and extensively removed than farther north, though higher now than elsewhere, and, therefore, " this probably was originally the highest part of the arch within the limits of the state of Ohio." According to K. Bell, of the Canada survey, the geanticline is continued northward across the west end of Lake Ontario to Lambton, in Ontario, Canada, and perhaps beneath Lake Huron, but its emergence to this distance is not proved. This range of broad islands and shallows had great influence on the rock-making of later Paleozoic time a view first recognized by James Hall in 1859 (Pal. N. Y., iii.). Upturnings in Nova Scotia and New Brunswick. Unconformability between the Upper Silurian and Lower Silurian rocks has been observed in Carleton County, N.B., just north of the boundary near Metapedia Lake, and also on Lake Temiscouata, and elsewhere (L. W. Bailey); and in Nova Scotia at Cape St. George, Arisaig, Lochaber, and from Kerrowgane down the East Kiver of Pictou, and north of Sunderland Lake. But through this epoch there was comparative quiet north of Gaspe in the northern part of the St. Lawrence Gulf ; for the great limestone forma- tion of Anticosti, which was begun in the Lower Silurian era, continued its unbroken progress through the whole prolonged era of revolution, and after- wards far into the Upper Silurian era. EUROPEAN. In America the disturbances closing the Lower Silurian were confined to regions of very thick depositions, and mountain-making was the final result of the upturning. Over central New York and farther west in the Conti- nental Interior, the beds of the Lower and Upper Silurian eras follow one another without any marked unconformability. Cases of intervening erosion may be found; for every period loses by erosion a large part of its depo- sitions in the supply of material for the beds of the following period ; but no case occurs of horizontal deposition on upturned Lower Silurian strata. In Europe the facts are similar. Over the Continental Interior of Europe, which includes all European Russia up to the Archaean mountains on either side, and the surface south to the foot hills of the Alps, the Upper Silurian beds lie conformably on the Lower Silurian. The cases of unconformability 534 HISTORICAL GEOLOGY. are found in western England and Wales, where the strata claim a thickness exceeding 20,000 feet independently of ash-ejections. The Upper Lland- overy and other Upper Silurian beds rest upon the upturned edges of the Lower Llandovery, Caradoc, or other inferior strata. ">In one district, between the Longmynd and Wenlock Edge, the base of the Upper Silurian rocks is found within a few miles to pass from the Caradoc group across to the Lower Cambrian rocks." (Geikie, p. 672.) Another remarkable region of disturbance is that of the northwest Highlands of Scotland, along the chain of mountains between Eriboll and Ullapool. For some distance east of this region, according to the investi- gations of Hicks, Lapworth, Peach, Home, and others, the Silurian and Cambrian rocks, which overlie the Archaean, are much plicated, and the plications, on nearing it, become overthrust flexures, often flexure-faulted, with the thrust westward. Then commences over the wide region a series of nearly horizontal thrust-planes of great extent, along which the Archaean and overlying formations are thrust westward, in some places for ten miles. Besides minor shovings, there are three maximum thrust-planes which overlap so as to carry the formations over one another, pile them to a great thickness, and produce a series of extensive unconformabilities between Archaean, Cambrian, and Lower Silurian terranes ; and undisturbed Lower Silurian limestone is often the base of the pile, with Archaean rocks above. The thrust-planes look like planes of bedding, and were long so considered. Under the enormous amount of friction along the lower thrust-plane, the materials at the bottom of the moving mass were sometimes folded over and curved under it as well as abraded or crushed ; and, in addition, through the aid of the heat generated, sheets of sericite schist were made along the plane out of the abraded feldspar, and layers of other foliated metamorphic rock out of other material, the strike of the foliation being more or less parallel with that of the thrust-plane. In some cases the softer pebbles of a Cambrian conglomerate (made of pebbles of quartz, gneiss, dioryte, granite) are drawn out so as to form "thin lenticular bands of mica or hornblende schist flowing round the harder pebbles of quartz-rock " ; and at one place Cambrian sandstones have been converted into schists containing mica, and quartzytes merge into quartzose sericite schists. The fossiliferous Silurian limestones below the thrust-plane are not generally altered, but in some places have been ren- dered crystalline. (Q. J. G. Soc., 1884, 1888, the latter giving full references to earlier writers on the subject.) In northern Ireland, where the Lower Silurian and Cambrian beds have a thickness of more than 7000 feet, there are evidences of metamorphism in portions of the beds, while others still retain their fossils, and mark their Siluro-Cambrian age. The Upper Silurian beds above are undisturbed and unaltered. Geikie states that the crystalline schists of the Scottish High- lands are prolonged over northern Ireland to Galway Bay, which makes the disturbed region 400 miles long. PALEOZOIC TIME UPPER SILURIAN. 535 The Ural Mountains include long ranges of upturned and more or less crystalline Lower Silurian rocks, but it remains undetermined whether or not there is unconformability with the Upper Silurian beds. Of the 204 species of fossils in 68 genera, found in the Lower Lland- overy beds, 104 species in 45 genera still exist in the Upper Llandovery. (Etheridge.) NEOPALEOZOIC SECTION. In contrast with the EOPALEOZOIC part of geological history, when vast continental seas prevailed, a condition well styled thalassic, 1 both as regards geography and life, the NEOPALEOZOIC was the time of the in- creasing emergence of the land over large areas, and the emergence also of life in various forms, until in eastern North America a great semi-continent existed, over 1000 miles wide, which was covered with grand forests and other vegetation, and populated by Amphibians and Reptiles of ancient kinds, and by the largest of Insects, besides other inferior terrestrial Invertebrates. UPPER SILURIAN ERA. SYNONYMY. Upper Silurian, Murchison, Phil. Mag., vii., July, 1835; Hep. Brit. Assoc., Aug., 1835; Silur. System, 1838. Upper part of Silurian, Sedgwick, Rep. Brit. Assoc., 1835; Proc. G. Soc., 1838; Q. J. G. Soc., Jan., 1846. Silurian, Sedgwick, Q. J. G. Soc., 147, 1852 (the Lower Silurian being made Upper Cambrian); Lapworth, G. Mag., 1879, p. 13 ; H. B. Woodward, Geol. Eng. and Wales, 1887. Murchisonian, D'Or- bigny, Pal. et Geol., ii., 301, 1851. Bohemien, A. de Lapparent, Tr. de Geol., 1883. NORTH AMERICAN. J SUBDIVISIONS. ( 3. Upper Pentamerus epoch. 3. Lower Helderberg U Sha i y lim e s tone epoch. Period. ( ^ Lower Pentamerus epoch. 2. Onondaga Period. Salina beds, Water-lime, Tentaculite limestone. ( 3. Niagara epoch. Shale and limestone. 1. Niagara Period. < 2. Clinton epoch. Clinton group. ( 1. Medina epoch. Oneida and Medina beds. The map on page 536 (Eig. 737) presents a general idea of the dry land of North America at the opening of the Upper Silurian. The shore line of the time was not far outside of the Archaean limits (indicated by the dotted line), showing that the growth of the continent had been mainly along its Archaean borders. There was an extension of the land over the 1 With Homer, the Qd\aff 740 and 741 represent Lamellibranchs ; and 742, 743, Gastropods, the last a Bucania. PALEOZOIC TIME UPPER SILURIAN. 545 Tracks, probably of a Sea-worm, are represented by Fig. 744. These tracks cover large surfaces of the Medina sandstone, and are occasionally found in the Oneida conglomerate. They are simply impressions, the material being 745. 744. Fig. 744, Harlania Kalli ; 745, Cruziana (Kusophycus) bilobata (x 2). Hall. sandstone, and without structure internally, except the occasional occurrence of parallel or concentric layers, due to deposition in the depressions. Fig. 745 represents another form of track supposed to be of Molluscan origin. The following figures represent Corals, a Bryozoan, and a Graptolite of the Clinton group: Figs. 746, 747, one of the common Cyathophylloid Corals 74C 749 750 CORALS, GRAPTOLITE, BRYOZOAN. Figs. 746, 747, Zaphrentis bilateralis ; 748, a, Palaeocyclus rotuloides; 749, a. Monticulipora ; 750,'a, Graptolithus Clintonensis. Hall. of the genus Zaphrentis, the latter a view from above ; 748, a small disk- shaped Coral; 749, a minutely columnar coral-shaped Bryozoan of the genus Monticulipora; 750, a Graptolite; 750 a, an enlarged view of the same. Other Clinton fossils are shown in Figs. 751-760. A finely reticulate Bryozoan of the genus Fenestella (Fig. 751) is represented enlarged in 751 a. Fig. 752 is that of the characteristic Brachiopod, Pentamerus oblongus, and opposite views of the hinge end of the cast of the interior are given in Figs. 753, 753 a. Figs. 754, a represent the Brachiopod, DANA'S MANUAL 35 546 HISTORICAL GEOLOGY. Atrypa reticularis, which continues on through the Devonian; Fig. 756, a Chonetes a genus of the Productus family. There were also species of Orthoceras. Besides these, Figs. 759, 760 represent tracks probably of Mollusks. The Cruziana (Rusophychus), called also Bilobites (Fig. 745), is a large 751-760. ^ilpiPs iw Isis^ Iff Ipf - 'SSI: m MOLLUSKS. Figs. 751, a, Fenestella prisca ; 752, Pentamerus oblongus ; 753, a, part of casts of the interior; 754, a, Atrypa reticularis ; 755, o, Hyattella congesta ; 756, Chonetes cornutus ; 757, Avicula rhomboidea ; 758, Cyclonema cancellatuin ; 759, track of a Lamellibranch (x) ; 760, track of an Annelid ? (x). Hall. species, the figure being reduced one half; other related kinds from the Clinton are narrower, and six to eight inches long. The Cephalopods include Orthoceras desideratum; also species of the genus Discosorus of Hall, near Actinoceras in its broad beaded siphuncle, but having a shorter shell, more rapidly tapering and slightly curved ; the species D. conoideus extends into the Niagara epoch. Trilobites occur of the genera Calymene, Dalmanites, Ceraurus, Illcenus, Homalonotus and others, and some kinds are identical with Niagara species. The remains of Fishes, reported from the Clinton beds of Pennsylvania, are a small portion of a spine referred to a Shark, named by Claypole Onchus Clintonif together with fragments of what appear to be fish scales and plates. The spines from British Upper Silurian beds, on which the genus Onchus was established, are now regarded as portions of the telsons of species of Ceratiocaris ; and the American may be of similar relations, but this is not deemed probable. See under the Onondaga period, page 556. Remains of a Fish, Diplaspis Acadica Matthew (1888), are found at West- field, in southern New Brunswick, in Silurian shales that underlie Niagara beds, and are supposed to be of the Clinton group. The same beds contain " myriads " of the Ceratiocaris pusilla of Matthew., PALEOZOIC TIME UPPER SILURIAN. 547 A few of the many Corals in the Niagara group are represented in the following figures, 761-766. Fig. 761 is one of the Cyathophylloids or cup Corals ; 762, a Favosites, a columnar, tabulate Coral, so named from favus, a honeycomb, in allusion to its columnar structure ; 763, a chain Coral, or 761 COBALS. Fig. 761, Chonophyllum Niagarense ; 762, a, Favosites Niagarensis; 763, Halysites catenulatus; 764, 765, Heliolites spiniporus ; 766, Stromatopora concentrica. Hall. species of Halysites, mostly imbedded in the limestones ; 766, a Stromatopora, a calcareous Hydroid, the lines showing the edges of the very thin, barely distinguishable layers. Figs. 767-770 are the forms of some of the common Crinoids and Cystoids. In Fig. 767 the arms clustered about the mouth of the Crinoid are perfect. Fig. 768 has the box-like body of a Cystoid, to which group it is related. It 767-770. CBINOIDS. Fig. 767, Ichthyocrinus tevis ; 768, Caryocrinus or natus ; 769, a, 6, c, Stephanocrinus angulatus ; 770, Troostocrinus subcylindricus. Hall. had slender arms, three to four inches long, fixed to the top of the box, which were very fragile and are seldom preserved. The stem is sometimes found six to eight inches long. The genus Stephanocrinus, Fig. 769, includes Crinoids with short delicate arms. Among Cystoids, Callocystites Jewetti, Fig. 444, page 429, is very common. Besides the above forms, the Niagara group has afforded the first of the 548 HISTORICAL GEOLOGY. Blastoids, or Bud-crinoids, which, like the typical Cystoids, have no free arms, and usually are pentagonal in form. A species from the Niagara lime- stone of Ohio is represented, without its stem, in Fig. 770. BBACHIOPODS. Fig. 771, Leptsena rhomboidalis ; 772, Plectambonites transversalis ; 773, a, Atrypa nodostriata ; 774, Meristina (Whitfieldella) nitida; 775, Anastrophia interplicata; 776, a, Rhynchotreta cuneata; 777, a, 6, Atrypina disparilis ; 778, o, Orthis biloba ; 779, a, Spirifer Niagarensis ; 780, a, Sp. sulcatus. Hall ; except 778, Meek. Some of the characteristic Brachiopods of the Niagara group are repre- sented, natural in size, in Figs. 771 to 780 all very abundant species. 781-784. LAMELLIBRANCHS AND GASTROPODS. Fig. 781, Megalomus Canadensis ; 782, Avicula emacerata ; 788, Plfttjr- stoma Niagarense ; 784, a, Platyceras angulatum. Leptcena rhomboidalis, Fig. 771, is one of the long-lived species as it began in the Trenton period and continued on, with little change, through the Devonian. PALEOZOIC TIME UPPER SILURIAN. 549 Lamellibranchs are not numerous, a common fact with limestones. One of them from the Coralline limestone, and also from Guelph in Ontario, is shown in Fig. 781 ; another more common form, an Avicula, in Fig. 782. Figs. 783, 784 are of two Gastropods, the latter also a Clinton group species. A Pleurotomaria (P. solarioides), from the Guelph limestone, has a diameter of four inches. There were also Conularice of unusual size. Cephalopods include species of Orthoceras, Actinoceras, Discosorus, Huronia, Gomphoceras, Trochoceras. The following figures, 785-789, are the forms of some of the Niagara Trilobites, all reduced one half or more. The Lichas Boltoni (Fig. 786) has sometimes a length of seven inches, and the Homalonotus (Fig. 787), remark- able for its small eyes, even a greater length. The Catymeue Niagarensis is very similar to the G. callicephala of the Trenton period (Fig. 690). 785-789. 785 TBILOBITKS. Fig. 785, Dalmanites limulurus (x J) ; 786, Lichas Boltoni (x J) ; 787, Homalonotus delphino- cephalus (x |) ; 788, Illaenus loxus (x |). CRUSTACEAN. 789, Beyrichia symmetrica; 789 a, same, natural size. Hall. Ceratiocarids, among Crustaceans, occur of large size. The telson, or tail-spine, of one from western New York, Ceratiocaris Deweyi, is over six inches long, indicating a length for the Ceratiocaris of nearly two feet, or as great as that of C. Angelini (Fig. 729). Characteristic Species. 1. Medina Epoch. Fig. 744, Arthrophycus Harlani H. (1853) = Harlania Halli Gcepp. (1852) = Fucoides Harlani Con. (1838). Fig. 739, Lingula cuneata Con. ; Atrypa ( Whitfleldella) oblata H. ; 740, Modiolopsis orthonota Con. ; 741, M. primigenia Con. ; 742, Pleurotomaria litorea H. ; P. pervetusta Con.; 743, Bucania trilobata Con., different views ; Oncoceras gibbosum H. ; Orthoceras multiseptum H. 2. Clinton Epoch. PLANTS. Buthotrephis gracilis H., B. ramosa H. A Lycopod (or Fern) has been reported from Ohio by E. W. Claypole (1878). It is of doubtful nature. 550 HISTORICAL GEOLOGY. ANIMALS. 1. Hydrozoans. Fig. 750, Graptolithus Clintonensis H. 2. Actinozoans. Figs. 746, 747, Zaphrentis bilateralis H. ; Favosites favosus, Favi- stella favosidea H., Palceocyclus rotuloides H., Gannapora junciformis H., Halysites escharoides Lamk., H. catenulatus, species of Cyathophyllum, Streptelasma, Aulopora, Diphyphyllum. 3.- Echinoderms. Caryocrinus, but rare. 4. Molluscoids. (a) Bryozoans. Fig. 751, Fenestella prisca Lonsdale ; PtUodictya, Stictopora, many species. (6) Brachiopods. Species of Lingula, Orthis, Plectambonites, JRhynchonella, Spiri- fer, Chonetes, and Pentamerus ; Fig. 752, Pentamerus oblongus Sow. ; some specimens are twice the size of the figure ; the interior of the shell is shown in Figs. 753, 753 a ; Figs. 754, a, Atrypa reticularis Linn. ; Figs. 755, a, Hyattella congesta Con. ( = Cama- rella congesta) ; Fig. 756, Chonetes cornutus. 5. Mollusks. (a) Lamellibranchs. Fig. 757, Avicula rhomboidea H. ; A. emacerata Con., Tellinomya machceriformis H., abundant. (&) Gastropods. Fig. 758, Cyclonema cancellation H. ; Bucania trilobata of the Medina also occurs here, besides other Gastropods. 6. Crustaceans. Homalonotus delphinocephalus, Calymene Clintoni Van. , C. Niaga- rensis, Ceraurus Niagarensis H., Phacops trisulcata H. (a) Ostracoids, or Bivalve Crustaceans. Fig. 789, Beyrichia symmetrica H., showing one of the valves; 789 a, same, natural size; B. spinosa H., Lockport. (b) Ceratio- carids. Ceratiocaris Deweyi H., specimens of the caudal spine, formerly supposed to belong to a Fish, and named Onchus Deweyi. Onchus Clintoni of Claypole is from the Iron Sandstone stratum of Perry County, Pa. (1884, 1885) ; that it belonged to a Fish is not certain. 7. Eurypterids (Limuloids). Eurypterus prominens H. Among the Clinton species are the following from the Lower Silurian : Orthis (Platy- strophia) biforata, Leptcena (Plectambonites) sericea, Bellerophon bilobatus, Calymene callicephala. The following are known in Europe : Orthis biforata, Atrypa reticularis, Coslospira (Atrypa) hemisphcerica Munch., Spirifer radiatus Sow., Pentamerus oblongus. 3. Niagara Epoch. 1. Spongiozoans. Astrceospongia, Astylospongia, Palceomanon of Rcemer in Tennes- see, in the upper part of the Niagara (or Meniscus) limestone ; Astrceospongia meniscus is the most.abundant. (Sil. Faun. W. Tenn., 1870.) 2. Hydrozoans. Dictyonema, common; Fig. 766, Stromatopora concentrica Goldf. 3. Actinozoans. Fig. 7Ql,Chonophyllum Niagarense H. ; Streptelasma calyculus H., Astrocerium venustum H., masses often 2 or 3 feet in diameter ; Strombodes gracilis Bill. ; 762, Favosites Niagarensis H. ; F. Gothlandicus Lamk., F. venustus H. ; 763, Halysites catenulatus Linn., H. escharoides Lamk., H. agglomeratus H. ; 764, Heliolites spiniporus H. ; 765, an enlarged view, showing the 12-rayed cells, and the interval of a cellular char- acter separating them, both of which are distinguishing characteristics of the genus Helio- lites; H. interstinctus Linn., H. pyriformis Guettard, Syringopora retiformis Bill., S. multicaulis H., Aulopora precia H., A. repens. 4. Echinoderms. Fig. 767, Ichthyocrinus Icevis Con., Lockport, sometimes twice as large as the figure ; 768, Caryocrinus ornatus Say, New York, Wisconsin, and Tennessee, named from Carya, the hickory-nut ; 769, fitephanocrinus angulatus Con., Lockport ; a, part of the stem, enlarged ; 6, joint ; c, base of the body, showing the 3 pieces of which it consists ; species of Melocrinus, Eucalyptocrinus decorus Phillips, New York, Kentucky, Tennessee; Camarocrinus Saffordi H., Tennessee; Lecanocrinus, etc. Also Fig. 444 (page 429), the Cystoid, Callocystites Jewetti H. ; Apiocystites elegans H., A. Canadensis, and A.. Huronensis of Billings, from Anticosti. Troostocrinus subcylindricus H. and PALEOZOIC TIME UPPER SILURIAN. 551 Wh., from the Niagara beds of Ohio, Fig. 770. The Star-fishes, Palceaster Niagarensis H., Glyptaster occidentalis H. 5. Molluscoids. (a) Bryozoans. Many species of delicate Corals of the genus Fenestella, resembling Fig. 751 ; Trematopora, and other genera. (&) Brachiopods. Fig. 771, Leptcena rhomboidalis Wilck. ; 772, Plectambonites transversalis Dalman ; Stro- phomena depressa Sow. ; 773, Atrypa nodostriata H., the Niagara form of this species ; 773 a, same, side view ; A. reticularis Linn. ; A. rugosa H. ; 774, Meristina ( Whitfield- elld) nitida H. ; 775, Anastrophia interplicata H. ; 776, a, Ehynchotreta cuneata Dalm. ; 777, a, b, Atrypina disparilis H. ; 778, Orthis (Bilobites) biloba Linn., 778 a, same, enlarged ; 0. elegantula Dalm., 0. hybrida Sow., Nucleospira pisiformis H. ; 779, Spirifer Niagarensis Con., 779 a, same, side view ; 780, a, Sp. sulcatus His. ; Pentamerus oblongus (Fig. 752), a Clinton group species, abundant in the Niagara limestone of the Mississippi basin ; Pentamerus occidentalis H., from the Guelph. 6. Mollusks. (a) Lamellibranchs. Fig. 781, Megalomus Canadensis H., from the Guelph, Canada ; 782, Avicula emacerata Con. ; Orthonota curta H. (6) Gastropods. Fig. 783, Platystoma Niagarense H. ; 784, Platyceras angulatum H. ; Murchisonia bivittata H., M. macrospira H., Subulites ventricosus H., Pleurotomaria solarioides H. (c) Pteropods. Conularia Niagarensis H., C. longa H., Lockport. (d) Cephalopods. Orthoceras annulatum Sow., 0. rectum Worthen, Orthoceras (Kionoceras Hyatt) strix Worthen ; Phragmoceras parvum H. and Whitf ., Huronia Bigs- byi Stokes, H. vertebralis Stokes, Gomphoceras Wabashense and G. angustum Newell, Pentameroceras mirum Barrande, Ascoceras Newberryi B., Hexameroceras delphicolum Newell, etc., Lituites Marshi Hall, Trochoceras costatum H., T. notum H.,T. Desplain- ense McChesney. 7. Crustaceans. Fig. 785, Dalmanites limulurus Green ; 786, Lichas Boltoni Bigsby ; 787, Homalonotus delphinocephalus Green, one specimen 7 inches long and 5 broad ; 788, Illcenus loxus H. ; Calymene Niagarensis H. , near Fig. 690 ; Ceraurus Niagarensis H. ; Proetus Stokesi Murch., at Lockport. The following genera and species of fossils have been identified in the Niagara beds of Littleton, N.H. : Favosites basalticus, F. Gothlandicus, Syringopora, Stromatopora, Halysites near catenulatus, Zaphrentis, Leptcena rhomboidalis, Stropheodonta, Pentamerus Knightii, Trematospira multistriata H., Pleurotomaria, Dalmanites limulurus abundant. In the Anticosti beds there are Cephalopods of the genera Orthoceras, Cyrtoceras, Oncoceras, Ascoceras, and Glossoceras ; and Trilobites of the genera Asaphus, Calymene, Illcenus, Phacops, Dalmanites, Encrinurus, Harpes, Lichas, etc., and among these Asaphus megistos and Calymene Blumenbachii. A section of the Anticosti group, or that of Anticosti Island, on the north side of the St. Lawrence Bay, opposite Gaspe, is particularly described by Logan in the volume of the Canadian Survey for 1863 (pages 298-310), and the fossils in its successive parts are enumerated from determinations by Billings, and also, where new, described by the latter. The following are some of the species common to the Niagara and Clinton groups : Halysites catenulatus (Fig. 763). Avicula emacerata (Fig. 782). Caryocrinus ornatus (Fig. 768). Orthonota curta. Eucalyptocrinus decorus. Modiolopsis subalata. Lingula lamellata. Ceraurus Niagarensis. Orthis elegantula (Fig. 723). Homalonotus delphinocephalus (Fig. 787). Leptsena rhomboidalis (Fig. 771). Calymene tuberculosa. Pentamerus oblongus (Fig. 752). Calymene Niagarensis. Rbynchonella neglecta. Dalmanites limulurus (Fig. 785). Atrypa reticularis (Fig. 754). Illsenus loxus (Fig. 788). Spirifer radiatus. 552 HISTORICAL GEOLOGY. Foerste reports the absence of several Clinton fossils from the Clinton beds along the borders of the Cincinnati geanticline in Ohio and Indiana that occur in New York (B. S. JV. H., 1889). According to Salter, a number of species of the Upper Silurian, and probably of this part of it, have been observed in Arctic rocks on the shores of Wellington and Barrow Straits and on King William's Island, lat. 72 to 76 ; Halysites catenulatus, Orthis elegantula, Favosites Gothlandicus, Leperditia Baltica Hisinger, species of Calophyllum, Heliolites, Cystiphyllum, Cyathophyllum, Syringopora, with Pentamerus conchidium Dalm., Atrypa reticularis, etc.; and, at the southern extremity of Hudson Bay, Penta- merus oblongus, Atrypa reticularis, etc. Trochoceras boreale Foord is from Wellington Channel. Between 79 and 82 5', the expedition of Captain Nares obtained, accord- ing to Etheridge, Corals of the genera Halysites, Favosites, Heliolites, Favistella, Zaph- rentis, Amplexus, Cyathophyllum, and Arachnophyllum, and Trilobites of the genera Bronteus, Calymene, Encrinurus, and Proetus, with Brachiopods of Pentamerus, Ehyn- chonella, Chonetes, Atrypa, Strophomena. About Lake Winnipeg, also, Upper Silurian fossils have been found. See Am. Jour. Sc., II., xxi. 313, xxvi. 119 ; III., xvi., 1878. The beds of northern Maine, about Square Lake, described by C. H. Hitchcock, have afforded both Niagara and Lower Helderberg fossils, and many of them are made new species by Billings. The Niagara beds of the vicinity of Cobscook and Penobscot bays, Maine, contain, besides Niagara fossils, some of the Clinton group ; the latter, in Penobscot Bay, are mostly confined to the lower half, but many Niagara species occur with them. (Shaler, 1886 ; Dodge and Beecher, 1892.) 2. THE ONONDAGA PERIOD. ROCKS KINDS AND DISTRIBUTION. The Onondaga period embraces two somewhat unlike formations ; one, the Salina beds of shales and marlytes, or the Salt group, the source of the brines of central New York and of rock salt in the western half of the state, as well as in Ontario and Ohio ; the other, the Water-lime group, in general an impure limestone, along with the overlying Tentaculite limestone. Each was of shallow water origin, and partly marsh-made ; but the former was produced under conditions suited for the deposition and storing of salt from the sea water. This classification was first proposed by D. Sharpe, in 1847. The following sections (Figs. 790, 791, from Hall), taken on a north-and- south line south of Lake Ontario, show the relations of the Onondaga beds (6, a, 6) to those above and below, they being underlaid in one section (Fig. 790) by the Niagara beds (5 c), Clinton (5 6), and Medina (5 a), and overlaid in the other (Fig. 791) by rocks of the Upper Helderberg (9), Hamilton (10 a, 10 6, 10 c) and Portage group (11), the Lower Helderberg being there absent. The rocks spread eastward to the Hudson Kiver valley, the Water-lime occurring as a thin stratum even east of the river in the base of Becrafts Mountain, near Hudson, N.Y., and also in Mount Bob, a few miles farther north, in each case resting on the upturned Hudson formation. They increase in thickness westward. They extend beyond New York over much of Ohio, cross Ontario to Lake Huron and northwestward to Mackinac in PALEOZOIC TIME UPPER SILURIAN. 553 Michigan, and thin out in Wisconsin. They also cross Pennsylvania south- westward. They have not been observed in Missouri, Iowa, or elsewhere in the Mississippi valley. They are absent from the Black Hills of Dakota, 790. 5a 10 c 10 b 06 y 10 a Sections illustrating the relations of the Onondaga beds. Hall. and nothing definite is known of their occurrence over the Rocky Mountain region, or the Great Basin, or in California, or any part of the Pacific Coast region. The group is 100 to 200 feet thick south of Albany in the Helderberg Mountains, 800 in Onondaga County, central New York, 1500 at Ithaca, 1600 in central Pennsylvania, 600 in northern Ohio, and only 100 in southern Ohio. The two formations, the Salina and Water-lime, are not consecutive strata, but more or less cotemporaneous, the Water-lime being thin where the Salina beds are thickest. Salina Group. The rocks of the Salina group are mostly reddish shales or marlytes, with little limestone, which is usually dolomyte ; or alternations of shales with thick beds of limestone. In either case, gypsum and rock salt are often present. The outcrop of the formation extends as a narrow belt across New York State, extending from the Helderberg Mountains south of Albany, westward, passing just north of Sharon Springs, Syracuse, and Batavia to the Niagara River above the Falls, where the thickness is but 300 feet. From this belt it dips southward beneath the higher beds of the Upper Silurian and Devonian, becoming 1000 feet below the surface in 25 miles nearly south of Batavia, and 1500 feet in 33 miles. At Syracuse the thickness of the formation is about 600 feet ; at Ithaca, 30 miles south of the belt, it is 1230 feet. In western Ontario, Canada, on Lake Huron, about Goderich, the thickness is over 1400 feet, the lower 600 feet consisting of limestone, shale, and salt, and the rest of dolomyte ; and to the south, near Cleveland, Ohio, there are 750 feet of shale, limestone, and rock salt beneath 800 feet of dolomyte. Salt springs occur in many parts of New York, west of Syracuse and Tully. Those around Onondaga Lake led, first in 1825, to the sinking of wells 70 feet to 75 feet deep at Salina, for the manufacture of salt by evapo- ration. Rock salt appears to have been first discovered in New York, in Bristol, Ontario County, at a depth of 1200 to 1300 feet ; but the discovery 554 HISTORICAL GEOLOGY. that attracted attention was made when boring for gas or oil, in 1878, in Wyoming County, a dozen years after the discovery at Goderich, and ten years before that near Cleveland, Ohio. By evidence from borings, rock salt is now known to occur in New York at depths of 800 to 3000 feet or more, over an area measuring 150 miles from east to west, and 60 to 65 miles in width if extending only to the Pennsylvania boundary. The northern limit of the area is near Morrisville, where 12 feet of salt were found, and near Leroy, 100 miles west of Syracuse, where a bed 40 feet thick exists. To the south, in Livingston and Wyoming counties, beds of salt occur at depths of 1000 to 2500 feet, and they have an aggregate thickness of 50 to 100 feet, some beds of pure salt being 40 to 80 feet thick. At Ithaca, the several beds of salt have together a thickness of 250 feet ; they alternate with shale between depths of 1900 feet and 3130 feet. At Goderich, six beds 6 to 35 feet thick were passed in a boring 1617 feet deep ; and other localities occur within 40 miles to the north, east, and south. Near Cleveland (at Newburg) there are four beds 5 to 50 feet thick in a range of beds 500 feet thick, between 2000 and 2500 feet below the surface. The evidence shows that the Goderich basin is independent of the New York, as pointed out in 1876 by T. S. Hunt. How it is related to the Cleveland basin is not positively known. The strata are non-fossiliferous ; but as they include beds of limestone, this is probably owing to loss of shells and other relics by trituration through the gentle movements of the water. The beds abound in mud-cracks, and other evidences that they were made as mud-flats or bottoms in shallow water. The facts are believed to prove that the region through which the salt beds extend was an area of great salt marshes or flats, or in other words " salt-pans," over which sea water, admitted at intervals from the interior continental sea, evaporated and deposited salt. The fineness of the material of the shales is such as would be produced by the gentle ripplings of such waters. The gypsum in the beds sometimes constitutes layers, but oftener parts of layers, or imbedded masses, as illustrated in the following figures (from Hall); but the most of the gypsum is connected with the overlying Water- lime beds. The lines of stratification in the beds sometimes run through the gypsum, as in Fig. 792; and in other cases the layers of the shale are bulged up around the nodular masses (Fig. 793). In all such cases, the gypsum was formed after the beds were deposited, by the action of sulphuric acid on an imbedded mass or bed of limestone, converting Ca0 3 C into gyp- sum (hydrous lime sulphate = Ca0 4 S 4- 2 H 2 0). It may be now forming. Sulphur springs, emitting sulphuretted hydrogen, are common in New York, and especially about Salina and Syracuse. Dr. Beck describes several, and mentions one, near Manlius, which is " a natural sulphur bath, a mile and a half long, half a mile wide, and 168 feet deep, a fact exhibiting in a strik- ing manner the extent and power of the agency concerned in the evolution of the gas" and showing, it may be added, that the effects on the rocks PALEOZOIC TIME UPPER SILURIAN. 555 below must be on as large a scale. These sulphur springs often produce sulphuric acid, by the oxidation of the sulphuretted hydrogen. There is a noted acid spring in Byron, Genesee County, N.Y., first noticed by Amos Eaton (Am. Jour. Sc.j xv., 1829), whose waters Beck showed to have a specific gravity of 1-113. The laminae which pass through the gypsum unal- tered, as in Fig. 792, are those which consist of clay instead of limestone. 793. .ueas ol'gypsuin (g) in limestone and calcareous siiaies. Hall. The gypsum is usually of an earthy variety, of dull gray, reddish and brown- ish, sometimes black, colors. That all the gypsum of the formation had this source is reasonably questioned. It may have been in part a deposit from the same sea waters that supplied the salt. Water-lime Group. The Water-lime rock, so-called because it is a hydraulic limestone, is an impure, thin-bedded magnesian limestone of usually a drab color. It some- times contains a little petroleum. It owes its hydraulic character to its impur- ities, as explained on page 79 (under Rocks). The group has, in general, the distribution above given for the Onondaga series. In the Helderberg Moun- tains it is about 150 feet thick, and nearly the same in the central part ; but farther north, near Oriskany Falls in Oneida County, it runs out. It con- tains much gypsum, and quarries of it are worked near Syracuse, and also in Cayuga and Genesee counties. In Northern Ohio, where the Onondaga series has a thickness of 600 feet, it contains layers of shale ; and gypsum is abun- dant at Gypsum, 10 miles west of San dusky. Hydraulic cement is made extensively from it in Ulster County, N.Y., at Rosendale near Rondout, whence the oft-used name "Rosendale cement," but not in Ohio, where the limestone is not suited for it. The presence of chert is one cause of the unfitness of the beds for the purpose. In the New York report by Vanuxem, the salt group between Oneida Creek and Cayuga Lake is stated to consist of (1) red shales with green spots, 1' to 500' thick; (2) the Lower Gypseous shales, light green and drab, alternating with No. 1 near the plane of junction ; (3) beds containing two ranges of gypsum in masses, and often containing hop- per-shaped cavities due to crystallized salt, the Vermicular limerock of Eaton ; and (4) im- pure limestone containing "Epsomites," or vertically grooved surfaces formerly supposed to have been made by the crystallizing of Epsom salts (the Stylolites, mentioned above). In middle Pennsylvania there are 700' of red shales, overlaid by 700' of variegated shale and 200' of gray shale (Claypole). The thickness of the formations overlying the Salina near the New York and Pennsylvania boundary is so great that no borings have yet penetrated to them. On the salt and gypsum industries of New York, see the Report of F. J. H. Merrill, Bull. N. Y. State Mus., iii., 1893, which contains maps showing the distribution. 556 HISTORICAL GEOLOGY. A dike of a chrysolitic eruptive rock, altered to serpentine, intersects the Salina group at Syracuse (though now concealed from view), which was first described by Vanuxem in 1839, and by Beck in 1842, and has recently been studied and explained by G. H. Williams (Am. Jour. Sc., 1887). 794-797. LIFE. The fossils that have been supposed to occur in the lower beds of the Salina group in New York are referred to the Niagara group, and those at the top are Water-lime species. Eegarding the Water-lime beds of Ohio as synchronous with the Salina and Water-lime of New York, the fossils of the Water-lime stand for those of the Onondaga period. But they are few in number, the limestone having originated, as its fine texture and impurity show, in shallow waters, under their gentle triturating action, and differing in origin from the Salina beds in having had more open connection with the Interior Continental Sea. Unquestioned remains of Fishes are among the fossils, and also the first of American terrestrial species, a Scorpion. Some of the characteristic fossils of the Water-lime are represented in the annexed figures. Fig. 794 is the more common species of Tentaculites of the Tentaculite limestone, and 795 is the same enlarged. It is regarded Figs. 794, 795, Tentaculites gyracanthus ; O.-L 5,1^11 ~f Q CTY , Q H -pf /l TTSo- 7Q 796, Leperditia alta; 797, Eurypterus RS th6 Sne11 O a Smali ^ ter OpO Sp. cyclopterus, Platyceras ventricosum, Dalmanites pleuropteryx. 3. UPPER PENTAMERUS. Pentamerus pseudogaleatus, Bhynchonella ventricosa, E. nobilis H. 820 820-82o. Acidaspis tuberculata, Fig. 820, upper view of head of an adult (1|) ; 821, segment of thorax (,l) ; 822, pygi- dium of adult (x ) ; 823, pygidium of young (x 3|) ; 824, dorsal view of larva (x 80) ; 825, profile view of same (x 30). Beecher. Atrypa recticularis and Leptcena rhomboidalis of the Niagara are supposed to be the only species that are continued into the Lower Helderberg. Some of the genera are as follows : 1. Spongiozoans. Stromatopora, very common in the Lower Pentamerus, con- stituting in some places a bed 3 or 4 feet thick. Also Ischadites, Hindia, Heceptaculites infundib u I iform is. 2. Actinozoans. Streptelasma, Zaphrentis, Michelinia (begins), Favosites (of which F. Helderbergice is often a foot across), Aulopora. 3. Echinoderms. Lepadocrinus, Anomalocystites, Sphcerocystites, Melocrinus, Cor- dylocrinus, Edriocrinus, Homocrinus, Coronocrinus, Protaster (P. Forbesii H.). 4. Brachiopods. Orthis (many species), Strophomena (Leptcena of Hall, 1892), Stropheodonta, Chonetes (2), Mhynchonella (numerous species), Pentamerus, Eatonia, Anastrophia, Spirifer (very many, some with dichotomizing ribs, a feature especially of later time), Cyrtina, Trematospira (several species), Meristella, Atrypa, Eensselceria. 5. Mollusks. Lamellibranchs. Aviculopecten, Mytilarca, Megambonia, Cypricar- dinia, Conocardium. Gastropods. Platyceras, Platystoma, Holopea, Loxonema, Murchisonia, Pleuroto- maria, Strophostylus, Euomphalus, Bucania. Cephalopods. Orthoceras of several species, Oncoceras ovoides H., Cyrtoceras. Pteropods. Conularia, Tentaculites, and Hyolithes. 6. Crustaceans. Besides those mentioned, Bronteus, Homalonotus, Cyphaspis, Proetus. The Ostracoid genera, Leperditia, Beyrichia, ^Echmina. The Lower Helderberg beds, near Eastport, southeastern Maine, include Favosites cervicornis, Leptcena rhomboidalis, Chonetes Novascoticus, ^Rhynchonella Wilsoni, Atrypa reticularis, Orbicluoidea tenuilamellata, Spirifer sulcatus, Orthis elegantula, Avicula naviformis, Calymene Blumenbachii, Homalonotus Dawsoni, Conulites Jlexuosus, Tenta- culites distans, Beyrichia lata, and others (W. A. Rogers). PALEOZOIC TIME UPPER SILURIAN. 563 For a list of 163 Upper Silurian species found at Arisaig, Nova Scotia, see H. M. Ami, Nova Scotia Inst. Sc., 1892. In this paper Ami remarks on the relations of the fossils that "they are much closer to the Ludlow rocks of Kendal, in Westmoreland, England, than to either the Upper Silurian species of Anticosti, of Ontario, or those of the state of New York." The species range from the Medina to the Lower Helderberg. Hall remarks that many Niagara species have their nearly related or representative species in the Lower Helderberg : thus, Orthis elegantula is represented by 0. subcarinata and 0. perelegans ; 0. hybrida by 0. oblata and O. discus ; 0. punctostriata by O. tubu- lostriata; Spirifer Niagarensis by 8. macropleurus ; S. sulcatus by 8. perlamellosus ; 8- crispus by 8. cyclopterus ; Strophomena (Orthothetes) subplana by 8. (O.) Wool- worthana. So also Pentamerus fornicatus of the Clinton is represented by P. galeatus. FOREIGN. The rocks of the Upper Silurian are widely distributed over the globe, though less universal than those of the Lower Silurian. They occur in Great Britain, Scandinavia, Eussia, Germany, Bohemia, and Sardinia, and in Asia, Africa, and Australia. They seem on a geological map to cover but small areas, but only because they are concealed by later formations. The rocks in Great Britain where best displayed are subdivided as follows : 1. May Hill (Gloucestershire) Sandstone, or Upper Llandovery group. Sandstones, with some arenaceous limestone ("Pentamerus limestone"), which terminate above in the Tarannon shales. American Equivalent, the Medina and Clinton groups. 2. Wenlock Group. Consists of (1) the Woolhope beds, limestone and shale; (2) Wenlock shale; (3) Wenlock or Dudley limestone. Amer. Equiv., the Niagara shale and limestone. 3. Ludlow Group. Consists of (1) the Lower Ludlow rock; (2) the Aymestry limestone ; (3) the Upper Ludlow ; (4) Tilestones. Amer. Equiv., the Onondaga and Lower Helderberg groups. These subdivisions are well exhibited in Shropshire or western England and in eastern and southern Wales. Between the Tilestones and the Ludlow are one or two thin bone-beds consisting of remains of Fishes and Crustaceans. In North Wales, and in Westmoreland, Cumberland, southern Scotland, and southwestern Ireland, the beds are mostly grits and shales, and are much upturned, with the subdivisions not distinct. The Wenlock group is repre- sented by the Denbighshire grit in North Wales, and the Coniston grits in Cumberland. The thickness is stated to be from 3000 to 5000 feet. Upper Silurian beds outcrop : in Russia over a large area south of the Gulf of Finland ; in southern Sweden ; about Christiania and some points to the north in Norway; in the Bohemian basin near Prague, where Barrande's formation E corresponds to the Niagara and Onondaga periods, and his F, G, H. approximately to the Lower Helderberg and Oriskany; in the Fichtelgebirge ; and the upper section only in the eastern Hartz, where the 564 HISTORICAL GEOLOGY. beds are the Hercynian of Beyrich; and under this name are placed, by Barrois, beds occurring at Erbray in the Lower Loire. They have been identified also in Sardinia, India, China, Australia, New Zealand, and the Argentine Republic. LIFE. The Wenlock and Ludlow beds abound in fossils, especially the former, which represent nearly the American Niagara group. Evidence of British land plants occurs in the Ludlow beds ; the earliest of British Fishes species of Pteraspis and Cephalaspis in the Lower Ludlow; the earliest of Scorpions, in the Upper Ludlow and the Upper Silurian of Gothland, Sweden. 826-831. 831 Fig. 826, Omphyma turbinata; 827, Cystiphyllum Siluriense; 828, Crotalocrinus rugosus; 829, Pentamerus Knightii; 830, Grammysia cingulata; 831, a, Pterygotus bilobus. 826, 827, from Edwards and Haime; 828, Murchison ; 829, Brown; 830, Naumann ; 831, Salter. LAND PLANTS. The Pachytheca of Hooker is supposed to be the spores or sporangia of a terrestrial plant (Q. J. G. Soc., xxxviii., 107, 1882). The Denbighshire grits of the Wenlock of North Wales have afforded the Nema- tophyton of Dawson, having loose tubular cells within, supposed to be from a tree of large size, but now admitted to be a Seaweed. The earliest of well- defined ferns has been described by Saporta for the schists of Angers, which PALEOZOIC TIME UPPER SILURIAN. 565 are referred to the Middle Silurian. It is a portion of the frond of a Neuropteris. ANIMALS. The genera of Corals, Crinoids, Brachiopods, Trilobites, and of other classes are to a large extent the same as in America. A Crinoid of an unusual form is represented in Fig. 828, a Crotalocrinus ; Corals, in Figs. 826, 827 ; a common Pentamerus, in Fig. 829. Trilobites are common, as in the American rocks. Some of the species are represented in Figs. 832-841. Figs. 832, 835, and 838 are of species from the Wenlock ; Figs. 833, 834, 836, 837, 839, and 840 range below, and all but 840 above, the Wenlock. Fig. 831, from Salter, is that of a large Limuloid, of the genus Pterygo- tus, from the Wenlock beds. It shows well the chelate termination of the antennae, but it is imperfect in wanting the four pairs of slender legs which. 832-841. Fig. 832, Sphaerexochus minis ; 833, a, Cheirurus bimucronatus ; 834, a, Encrinurus punctatus ; 835, E. variolaris ; 836, a, Phacops Downingii ; 83T, Acidaspis Brightii ; 838, A.. Barrandii ; 839, Cyphaspis megalops ; 840, Proe- tus latifrons ; 841, Hemiaspis limuloides. Figs. 832 to 840, after Murchison ; 841, after Woodward. are situated between it and the large posterior pair (see page 623). The jaws in the figure, one of which is separately shown in Fig. 831 a, are the basal portions of the posterior legs. Fig. 841 represents the Hemiaspis limuloides of Woodward, a form inter- mediate between a modern Limulus and the Eurypterids; the genus has species in both the Wenlock and Ludlow beds. A Ceratiocaris of the Ludlow group is shown in Fig. 842. Fig. 845, a spine (referred to a genus of Sharks, Onchus), is supposed to be from a Ceratiocaris. The first of Amphipod Crustaceans, Necrogammarus Salweyi, is reported from the Ludlow. A Scorpion has been found in the Upper Ludlow beds of Lesmahago in Lanarkshire, Scotland, and in beds of nearly the same age in Gothland, Sweden ; the latter is named the Palceophonus nuntius by Torell and Lind- 566 HISTORICAL GEOLOGY. strom, the generic name meaning the ancient murderer. Both specimens have traces of spiracles, showing them to have been terrestrial species. 842. Ceratiocaris papilio. Salter. The wing of an insect, Palceoblattina Douvillei of Brongniart, has been found in the sandstone of Jurques in northwestern France, and for the pres- ent it is the oldest known insect. Its relation to the Cockroaches, which is thought probable by Brongniart, is questioned by Scudder, a Neuropteroid character being thought more probable. The sandstone is of the age of the May Hill sandstone of England, at the bottom of the Upper Silurian. Jaws of Annelids of several species have been described by Hinde from the Wenlock and Ludlow groups. Fish-remains occur especially in the bone-bed below the Tilestones, and also in the Tilestones. Fig. 843 represents a head-shield of Pteraspis Bariksii Huxl. & S. Fig. 844 is the head-shield of a Cephalaspis so named from the Greek for a shield-like head. A complete animal, but different in species, and from the Devonian, is shown in Fig. 980 ; and Fig. 846 repre- sents probably part of the jaw-bone of a Cephalaspis. Fig. 843, Pteraspis Banksii, head-shield ; 844, Cephalaspis Murchisoni, inside of head-shield ; 845, spine of Onchus tenuistriatus = Ceratiocaris tenuistriata ; 846, part of jawbone of Cephalaspis(?) ; 847, shagreen pieces (?), Thelodus parvidens. Murchison. Fishes of the Shark tribe are supposed to be indicated by spines, teeth, and portions of the shagreen, or skin ; but all are doubtful. A number of Upper Silurian Fishes have been described from the rocks of Russia and Bohemia, including species of Coccosteus and Pterichthys, and the fin-spines of Sharks. PALEOZOIC TIME UPPER SILURIAN. 567 Characteristic Species. 1. Upper Llandovery. Petraia, species of Favosites, Heliolites, Syringopora, Holy- sites, Omphyma, Palceocyclus, Actinocrinus, Palceechinus, Tentaculites ornatus, Cornu- lites serpularius, Ccelospira Scotica, Ehynchonella neglecta, Meristella angustifrons, Stro- phomena arenacea, S. compressa, Pentamerus oblongus, P. caudatus, Stricklandinia lens, S. lyrata, Orthis lata, O. calligramma, 0. elegantula, Lyrodesma cuneatum, Pterinea sub- Icevis, Murchisonia angulata, M. articulata, Cyclonema quadristriatum, Euomphalus ala- tus, Haphistoma lenticulare, Holopella obsoleta, Conularia, Calymene Blumenbachii, Encrinurus punctatus, Illcenus Thomsoni, Proetus Stokesi, Phacops Stokesi; also Trinucleus concentricus, Lichas laxatus, Acidaspis, etc. 2. Wenlock Group. Petraia bina, Cyathophyllum truncatum Linn., Favosites Goth- landicus, F. fibrosus, Halysites catenulatus, H. interstinctus, Syringopora bifurcata, Cysti- phyllum Siluriense (Fig. 827), Stenopora fibrosa, Ptilodictya scalpellum, and many other Bryozoans ; Eucalyptocrinus decorus, Actinocrinus simplex, Crotalocrinus rugosus (Fig. 828), Marsupiocrinus ccelatus, Atrypa reticularis, Orthis elegantula, Ehynchonella Wilsoni, It. nucula, Pentamerus galeatus, Leptcena rhomboidalis, Spirifer elevatus, S. sulcatus, Nucleospira pisum, Obolus Davidsoni, Turrilepas* Modiolopsis complanata, Conocardium cequicostatum, Pterinea retroflexa, Grammysia cingulata (Fig. 830), Orthoceras, Lituites, Actinoceras, Tentaculites ornatus, Acidaspis coronata, A. hamata, Calymene tuberculosa, Homalonotus delphinocephalus, Lichas Anglicus, Phacops caudata, Encrinurus variolaris. 3. Lower Ludlow. Palceasterina primceva, Protaster Sedgwickii, P. hirudo, Om- phyma turbinata, Ehynchonella Wilsoni, JR. navicula, Cyrtia exporrecta, Spirifer crispus, Strophonella euglypha, Atrypa reticulans, Lingula lata, Pentamerus galeatus, Orthonota ajftnis, Loxonema sinuosum, Orthoceras Ludense, 0, annulatum, Phragmoceras, Lituites giganteus, Calymene Blumenbachii, Phacops caudata, P. longicaudata, Proetus latifrons, Acidaspis Brightii, Lichas Anglicus, Homalonotus delphinocephalus, Cyphaspis megalops, Hemiaspis sperata. 4. Aymestry Limestone. Tentaculites ornatus, Cyathophyllum truncatum, Penta- merus Knightii (Fig. 829), Atrypa reticularis, Shynchonella Wilsoni, E. navicula, E. Stricklandi, Lingula Lewisii, L. lata, Strophonella euglypha, Meristella ( Whitfieldella) didyma, Chonetes striatellus, Bellerophon dilatatus, B. trilobatus, Lituites giganteus, Orthoceras tenuiannulatum, Pterinea Sowerbyi, P. hians, Calymene Blumenbachii, Homalonotus delphinocephalus, Phacops caudata. 5. Upper Ludlow. Lingula minima, L. lata, Orbiculoidea rugata, Atrypa reticularis, Ehynchonella Wilsoni, Orthis elegantula var. orbicularis, O. lunata, Stropheodonta Jilosa, Strophonella euglypha, Chonetes striatellus, C. latus, Orthonota angulifera, Platyschisma helicites, Holopella obsoleta, H. gregaria, H. conica, Cyclonema corallii, Murchisonia corallii, Bellerophon carinatus, Orthoceras bullatum, Homalonotus Knightii, Encrinurus punctatus, Phacops Downingii, Calymene Blumenbachii, Ceratiocaris, Dictyocaris, Entomis, Beyrichia, Leperditia, Eurypterus, Pterygotus bilobus (Fig. 831), Slimonia, Stylonurus. Fishes from the Lower Ludlow include only Scaphaspis (Pteraspis) Ludensis ; from the Upper, mostly from the bone-bed, Cephalaspis ornata, C. Murchisoni, Plectrodus mirabilis, P. pleiopristis, Pteraspis Banksii, P. truncata, Scaphodus Ludensis, Thelodus parvidens, Thysetes verrucosus, and others. There are, also, in the same rocks Coprolites from some of these Fishes, containing fragments of the shells of the Mollusks and Cri- noids on which they fed. Remains of Fishes have also been found in the upper part of the Upper Silurian of Russia and Bohemia. Ctenacanthus Bohemicus Barr, abundant in Stage G. The Hercynian fossils of the Hartz and Erbray have closer analogy with those of the Lower Helderberg than with those of the Upper Helderberg, but they also have close 568 HISTORICAL GEOLOGY. analogy with the Oriskany in the large number of species of Platyceras, Spirifer, and Strophomenids. ( J. M. Clarke, on the Hercynian Question, 42d Rep. , Eep. N. Y. State Mus., 1889.) All writers have made the Limuloids of the Middle and Upper part of the era good evidence of equivalency. But there are large species in the Lower Silurian ; and, more- over, they may have lived in brackish or fresh waters, as some facts render probable, so that they really have very little chronological value. According to Barrande, the following are characteristic species of his subdivisions, E, F, G, H, of the Upper Silurian of the Bohemian basin : E. Graptolitic slates, passing above into limestone, corresponding to the Niagara period. Many Graptolites : Halysites catenulatus, Leptcena rhomboidalis, Atrypa (Dayia) navicula, Pentamerus Knightii, Bhynchonella, Spirifer, Orthis. Many species of Ortho- ceras, and others of Cyrtoceras, Gomphoceras, Trochoceras, etc. ; Calymene, Phacops, Lichas, Cyphaspis, Illcenus, Cheirurus, Acidaspis, Proetus. F. A dark limestone, cherty above : Favosites Gothlandicus, F.fibrosus ; Orthis palli- ata, Atrypa reticularis, A. comata, Pentamerus galeatus, Bhynchonella, Spirifer, Leptcena Verneuili; Phacops, Lichas, Bronteus; Tentaculites, Goniatites. G. A cherty or impure limestone, with an intermediate shaly layer: Atrypa reticu- laris, Pentamerus ; Tentaculites ornatus ; Lituites, Goniatites, Orthoceras Midas ; Phacops fecunda, Dalmanites Hausmanni, Bronteus, Cheirurus Sternbergi, Proetus, Harpes. H. Shale and sandstone: Leptcena, Orthoceras, Lituites, Goniatites, Phacops fecunda, Proetus, Tentaculites. In Russia, on the Baltic, south of the Gulf of Finland, the four subdivisions, G, H, I, K, have afforded the following species : G. Rhynchonella affinis, Strophomena pecten, Orthis Davidsoni, Pentamerus borealis, Leperditia Keyserlingi, Phacops elegans. H. Dolomytes and Coral limestone : Syringopora bifurcata, Favosites Gothlandicus, Haly- sites, Pentamerus oblongus. I. The Lower Oesel Zone, dolomytes = Wenlock : Euom- phalus funatus, Orthoceras annulatum, Spirifer crispus, Orthis elegantula, Leptcena transfer salis. K. The Upper Oesel Zone, limestones : Pterinea retroflexa, Chonetes striatellus, Spirifer elevatus, Beyrichia tuberculata. In New South Wales occur Favosites Gothlandicus, Heliolites inter stinctus, Calymene Blumenbachii, Encrinurus punctatus, Phacops caudata, Atrypa reticularis, Strophomena pecten, Pentamerus Knightii, P. oblongus, Meristella tumida, Orthoceras ibex. American Upper Silurian Species Occurring Elsewhere. Halysites catenulatus, Niagara, Great Britain (Llandeilo, Wenlock, Aymestry), Norway, Sweden, Russia, Eifel. Heliolites pyriformis, Niagara, Great Britain (Wenlock, Ludlow), France, Sweden, Russia, Eifel. Favosites Gothlandicus, Bohemia. Eucalyptocrinus decorus, Niagara, Great Britain (Wenlock), Scandinavia. Orthis elegantula, Clinton, Niagara, Great Britain (Wenlock, Ludlow), Gothland. Orthis hybrida, Niagara, Great Britain, Gothland. Orthis biloba, Niagara, Great Britain (Wenlock), Gothland. Plectambonites transversalis, Anticosti, Great Britain (Wenlock), Gothland. Leptcena rhomboidalis, Trenton, through Upper Silurian, into Devonian, Great Britain (Wenlock, Ludlow), Sweden, Russia, Belgium, Eifel, France, Spain. Strophomena rugosa, Niagara, Helderberg, Great Britain (Wenlock, Ludlow), Gothland, . Russia, Eifel. Spirifer crispus, Niagara, Great Britain (Llandeilo, Wenlock), Gothland. Atrypa reticularis, Clinton, Niagara, Helderberg, Great Britain (Wenlock, Ludlow), Gothland, Bohemia, Russia (Urals, Altai). PALEOZOIC TIME UPPER SILURIAN. 569 Ccelospira Scotica, Clinton, Great Britain (May Hill). Hhynchonella bidentata, Niagara, Great Britain (Wenlock). Hhynchotreta cuneata, Niagara, Great Britain (Wenlock), Gothland. Ehynchonella Wilsoni, Niagara, Great Britain (Wenlock). Rhynchonella Stricklandi. Pentamerus galeatus, Helderberg, Great Britain (Wenlock, Ludlow), Eifel. Pentamerus brevirostris, Niagara, Great Britain (Devonian). Pentamerus oblongus, Clinton, Niagara, Great Britain (Wenlock). Pentamerus Icevis, Great Britain (Wenlock). P. Knightii, Great Britain (Ludlow). Anastrophia interplicata, Great Britain. Bellerophon bilobatus, Trenton to Clinton, Great Britain (Wenlock). Orthoceras annulatum, Clinton, Niagara, Great Britain (Wenlock, Ludlow). Orthoceras virgatum, Niagara, Great Britain. Calymene tuberculosa, Niagara, Great Britain (Bala, Wenlock, Ludlow), Sweden, Norway, Bohemia, France. Homalonotus delphinocephalus, Clinton, Niagara, Great Britain (May Hill, Wenlock). Proetus Stokesi, Niagara, Great Britain (Wenlock). Trinucleus concentricus, Trenton, Hudson, Great Britain (May Hill). Tentaculites ornatus, Water-lime, Great Britain (May Hill, Ludlow). Arctic American Upper Silurian Species Occurring Elsewhere. Stromatopora concentrica, Great Britain, Eifel. Halysites catenulatus, Great Britain, Norway, Sweden, Russia, United States. Favosites Gothlandicus, Great Britain, Sweden, United States. Favosites polymorphus, Great Britain, France, Belgium, Eifel. Receptaculites Neptuni, Great Britain, Belgium, Eifel, United States. Orthis elegantula, Great Britain, Gothland, Russia, United States. Atrypa reticularis, Great Britain, Gothland, Urals, Altai, United States. Pentamerus conchidium, Gothland. Encrinurus Icevis (?), Gothland. Leperditia Baltica, Gothland. The number of Lower Llandovery (top of Lower Silurian) species that are known to pass into the Upper Silurian in Great Britain is 104 in 45 genera, out of a fauna of 204 species in 68 genera (Etheridge). Devonian Relations of the Loicer Helderberg Fauna. This subject has been ably discussed by J. M. Clarke, in the 42d Annual Report of the New York State Museum, 1889, under the title "The Hercynian Question." The terms Hercynian shales and Hercynian fauna were first given by E. Kayser, in a paper on the oldest Devonian formations of the Hartz Mountains, to the second of four for- mations in the region the " Unterer Wieder Schiefer" of A. Roemer. It contains the oldest fauna of the Hartz, and was pronounced by him the oldest or lowest Devonian, and also the equivalent of Barrande's Upper Silurian divisions, F, G, H. Clarke gives the following summary of the history of Hercynian ideas : "A. ROEMER, in 1843, regarded the fauna in the Hartz, in its typical development, as Upper Silurian ; but subsequently made the Cephalopod facies and Brachiopod facies thereof represent distinct faunas, the former Devonian, the latter Silurian. Beyrich, in 1867, believed the two faunas of Roemer one, and suggested their equivalence to the Bohemian F, G, H, and their relation to the Devonian. KAYSER, in 1878, demonstrated their unity and Devonian character and regarded them as the lowest Devonian, and as representing a calcareous 570 HISTORICAL GEOLOGY. facies of the Coblenzian fauna of the Rhine, and paralleled them with the Bohemian faunas of F, G, H, taken in their entirety ; in 1880 he regarded them as a lower (not lowest) Devo- nian fauna and still as a calcareous facies of the Coblenzian ; but in 1884 he appears to have resumed his original position as to the age of the Hercynian, and modified his conception of the parallelism with the Bohemian fauna by removing from his equivalent the lower portion of F. ... BARROIS, in 1889, made the Hercynian lowest Devonian, but dif- fered from Kayser (1878, 1880), in regarding it, not as a calcareous facies of the Spirifer- sandstein or Coblenzian, but as such a facies of the older Gedinnian, considering the Bohemian G as its equivalent." Kayser concluded further that the Lower Helderberg formation of America was Hercynian, that is, lowest Devonian, contrary to the views of Barrande, who had made it Upper Silurian, and the equivalent of the three divisions in his Bohemian system just mentioned. In his recent Lehrbuch (1891), Kayser leaves the Water-lime in the Upper Silurian. Some of the alleged Devonian characteristics of the Lower Helderberg are : its many species of Dalmanites of the D. Hausmanni type ; its species of Phacops, of the type of P. fecunda, and of Homalonotus, of the type of H. Vanuxemi ; the occurrence of many species of Platyceras; the special Devonian features among several genera of Brachiopods and Lamellibranchs. On the contrary the formation is unlike the Hercynian in containing no Goniatites, and like the Silurian in including several species of Cystideans. Mr. Clarke presents in his paper a full account of the discussion ; and while he unhesitatingly refers the Oriskany formation to the Devonian, on the ground of its fauna, he leaves the question as to the Lower Helderberg without a decision. No attempt is made to compare the American fauna with that of the Ludlow beds of England, which is really the typical fauna of the later part of the Upper Silurian the limits of the Devonian and Silurian having been first laid down by Murchison and Sedgwick. GENERAL OBSERVATIONS ON THE UPPER SILURIAN. GEOLOGICAL AND GEOGRAPHICAL CHANGES DURING THE UPPER SILURIAN. NORTH AMERICAN. In the region of the Appalachian geosyndine. As in the Lower Silurian, the successive formations have their greatest thickness along the Appalach- ian geosyncline, and at the same time limestones were the prevailing rocks of the continental interior. The thickness of the argillaceous beds and sandstones of the East indicate that during the Niagara period the deepening of the geosyncline amounted, in Pennsylvania, to at least 1500 feet in the Medina epoch, over 2000 in the Clinton, 1500 in the Niagara and Onondaga, and 500 in the Lower Helder- berg, in all 5500 feet. In the Onondaga period, the subsiding area extended up into New York, west of its center ; for it was there that the Onondaga beds were formed to a thickness of 1000 feet, with evidence in many parts of shallow-water origin. In the Lower Helderberg, and in the following Oriskany periods, the greatest thickness of the beds was in the eastern half of the state. No sediments for rock-making over the continent from the Atlantic Ocean. - Although the Champlain channel between the St. Lawrence seas and those of New York was again opened wide during the Lower Helderberg period, it PALEOZOIC TIME UPPER SILURIAN. 671 still gave no passage to coarse sediments; for the rocks formed over the channel were mainly limestone. So again, over the continental border from New York to Georgia, since Upper Silurian rocks are unknown along the border region, no sediments were supplied to the interior sea across this border from the Atlantic. Upper Silurian beds may exist there beneath the Cretaceous or Tertiary formations, or in the sea bottom outside ; but if so, the broad region of Archaean making the protaxis, without Upper Silurian beds, lies between. The Continental Interior received no Atlantic sediments. It has further been shown that the Upper Silurian formations of New England and eastern Canada and Newfoundland were in general made, not on the borders of the open ocean, if so at all, but within the limits of channels or bays bounded by Archaean ridges, or ridges of Archaean and Lower Silurian rocks. Of Pacific sea-border beds belonging to the Upper Silurian nothing has come to light. In the Arctic regions the rocks occupy a large basin or area, quite distinct from that of the Continental Interior. Its limits are unknown. Influence of the Cincinnati geanticline. The influence on the eastern interior sea of this barrier of emerged land and shallow seas was strongly marked. Owing to changes in level that were in progress, shifting the areas of deepest water, large changes were made from time to time in the courses of the tidal movements, in the character of the depositions, the clearness or foulness of the water, and accordingly in the character of the life. With clear, deep waters, life of great variety abounded and limestones were formed ; but with sediment-laden waters, or waters half freshened by contri- butions from the land, the living species were only those that could survive under such adverse circumstances. Abrupt variations in the rocks and the life become thus intelligible. It is hence easy to understand that a Niagara epoch might be followed, through a wide shallowing of the seas, by a region of immense salt-pans (evaporating sea-border flats) over a large part of New York, making the Salina group of rocks, while to the eastward, southward, and west- ward a tide-washed region existed, that of the Water-lime group, free from saline deposits because the tides had access; and that fresh-water and brackish-water flats, containing species of Eurypterids, might well have been a feature, at the same time, of the sea borders. Then the occur- rence of a slight subsidence would account for clearer seas again, for a restored fauna, and the making of Lower Helderberg limestones, and also for the extension of the limestones over eastern New York to Montreal in the St. Lawrence Channel, and southward over western New Jersey and part of Pennsylvania. Such salt-evaporating basins are due to local condi- tions and cannot be a universal feature of a period. Large shallow-water and emerged areas over the continent characteristic of the Upper Silurian era. The absence of Upper Silurian formations from much of the region west of the Mississippi, and their thinness where present, 572 HISTORICAL GEOLOGY. is a remarkable feature of the era. Even in the Laramide Eange of southern British America, McConnell found the Upper Silurian series only 1500 feet thick ; and in the Wasatch Eange, according to King, the thickness of the whole Silurian is but 1000 feet. The era began, as the Medina rocks show, with shallow waters over central New York, and probably large, emerged areas east of the Mississippi as well as west. In its progress through the Clinton epoch there were still shallow waters and emerging lands ; for the extensive beds of iron ore, ranging far south and west to Wisconsin, are evidence of great seashore flats through long intervals over much of the eastern half of the continent. In the Niagara epoch there were somewhat deeper and purer waters over the Interior Continental Seas, but the areas were not of very wide extent, and the epoch closed through the coming on of another period, the Onondaga, in which again great seashore flats pre- vailed, with feeble submergences or emergences where any occurred. The length of this period of great briny flats and salt deposits which were 100 miles or more long in the state of New York, and twice this to Goderich, on Lake Huron cannot be estimated; for thinness of rocks means nothing as regards elapsed time where a region is undergoing no oscillations of level, or only those of extreme slowness. The prevailing characteristic of the continent during the early and middle Upper Silurian, that of shallow seas and emerging seashore flats, continued on, with little change, through the closing Lower Helderberg period; for the formations are unknown over the Mississippi basin and farther west, and have their greatest extent along the region of the progressing Appalachian geosyncline, and its temporary prolongation northward through the Hudson and Champlain depressions to Montreal. The period of briny fiats unfavorable to aquatic life. Only two species of the Niagara fauna, the widely ranging Leptcena rhomboidalis and Atrypa reticularis, are known to occur in the Lower Helderberg beds, although the epoch which intervened was only one of muddy, briny flats. But the remark applies only to eastern North America, for nothing has been ascertained with regard to the Onondaga and Lower Helderberg faunas for the larger part of the continent. No upturning s at the close of the Upper Silurian. The era appears to have passed and ended quietly. It had slow and gentle oscillations in level, like other geological eras, but it was marked with no great upturning in its progress, and with none at its close. The Lower Helderberg formation graduates into that of the opening Devonian, and if transferred to the Devonian, the statement would still hold true. The eastern continental border related in life to the European. In Canada and New England the formations of the Upper Silurian have not yet been so fully distinguished and described that the succession of events for this part of the continental border can be deduced. But the fact that the region was distinct from the Interior Continental region has been well made out from the Upper Silurian fossils, by Salter and Billings, who state the following facts : PALEOZOIC TIME UPPER SILURIAN. 573 In the beds of this region of the Cambrian and Canadian periods there are Salterella rugosa Billings, closely like the Scottish ; S. Maccullochi Salter ; Kutorgina cingulata B., said by Davidson and Hall to occur in the Lingula flags; Acrotreta gemma B., very near A. subconica Kutorga; four species of Piloceras, a genus described from Scotland, but not known in the United States; Holometopus Angelini B., very near H. limbatus Angelin, of Sweden; Nileus macfops B., N. scrutatus B., N. ajfinis B., all closely allied to N. armadillo Dalman; Harpides Atlanticus, very near Angelin's H. rugosus of Sweden. In beds of Hudson age there are Ascoceras Cana- dense B., A. Newberryi B., and Glossoceras desideratum B., not found in the United States. In the Upper Silurian there are, as shown by Salter, the British species, Rhynchonella Wilsoni Sow., Grammysia triangulata Salter, G. cingulata His., Platyscliisma helicoides Sow., Platyceras Haliotis Sow., Bellerophon expansus Sow., B. carinatus Sow., Orthoceras bullatum Sow. (?), O. ibex Sow., Homalonotus Knightii Konig, Phacops Downingii Salt. ; to which Billings adds Rhynchonella Stricklandi Sow., and Lituites Ameri- canus B., very near, if not quite identical with L. giganteus Sow. Billings, who furnished the above list of species, adds that, through the Cambrian and Canadian periods, there is a decided European tinge in the life, but in the Trenton period its character was peculiarly American. Then in the Hud- son epoch there was again a European tinge, which increased in strength through the Upper Silurian. H. M. Ami has given (1892) a list of 163 fossils from the Upper Silurian beds of Arisaig, Nova Scotia, and states that a closer relation exists between the fauna and that of the Ludlow rocks of Kendal in Westmoreland, England, than with either the Silurian rocks of Anticosti, Ontario, or New York. EUROPEAN. The endogenous growth of the European continent during the Upper Silurian era is manifest, though of less regular progress than that of North America. The Upper Silurian formations over the British Isles were not on the outer Atlantic border, but on the opposite side of a border region of Archaean and Lower Silurian rocks, and this inner side continued to be the region of growth to the end. Moreover, there appear to have been two or three confined and parallel troughs. In Scandinavia and Russia, part of France and the Spanish peninsula, the same is true. All the Upper Silurian rocks of Russia are the work of an Interior Continental Sea, wi^h- out oceanic aid ; and this great Interior Sea extended south and west over Hungary and Austria to Bohemia and the Alps. The Mediterranean Sea is related to the continent like the West Indies and Mexican Gulf to America. The progress through the era was in general quiet ; for the Upper Silu- rian rocks are conformable in superposition. They are horizontal, or very nearly so, over the great interior region in Russia and elsewhere. Nearer the ocean, in England, the rocks to a considerable extent pass regularly upward 574 HISTORICAL GEOLOGY. into the Devonian. But in the western part in Wales, and in the Lake region to the north, they lie unconformably beneath the Old Red Sand- stone (Devonian), proving thereby that an epoch of local mountain- making in that region closed the period. Similar evidence of disturbance exists in Ireland. BIOLOGICAL PROGRESS. The records of the Upper Silurian era add to the terrestrial fauna the earliest of Arachnids, or Spiders, in the form of Scorpions, and additional species of Insects. The former are in the successional line of the Euryp- terids, whose earliest species is Lower Silurian ; the Insects are structurally in the line of the Myriapods, although no antecedent species of Myriapod is yet known. The Cockroaches are Orthopters, and species of imperfect metamorphosis, like the Hemipters. The relations of the above-mentioned groups are illustrated in the course of the General Observations on the Paleozoic, on pages 721, 722. Among marine Invertebrates, the era is marked by a large diminution in the number of species and genera of Graptolites and Trilobites Lower Silu- rian characteristics ; by an abundance of Cystoids and Orthids also Lower Silurian in aspect ; by an increase in the number and size of the Brachiopods of the families of Spiriferids, Pentamerids, and Productids Devonian char- acteristics ; by an increase in the Pteropods of the Conularia type ; by an increase in the number of Gastropods of the Platyceras (Capulus) type, and in the number of species and genera of Polyp-corals, Crinoids, and Asterioids which also look toward the Devonian; by an increase in the number and variety of Eurypterids and Ceratiocarids facts having the same bearing. Still more marked is the advance from Entomostracans to Tetradecapod Crustaceans ; and far beyond this is the appearance of Insects. It is re- markable that the first remains of Scorpions should have been found in Europe and America in rocks of very nearly the same age. But it may be that earlier specimens are yet to be found. Fishes, the only Vertebrates of the Upper Silurian, were represented by Placoderms, the mail-clad type that first appeared in the Trenton Period of the Lower Silurian, and possibly also by Selachians. But no remains of other Ganoids have yet been found in the beds, although reported from the Trenton. Rarity in fossils of lime-secreting aquatic species is not common. Remains of Chimseroids, mostly cartilaginous species, also are absent. CLIMATE. There is no evidence that the climate of America was roughened by frigid winds, or that the ocean was much modified in temperature by polar currents. The species living in the waters between the parallels of 30 and 45 were in part the same with, or closely related to, those that flourished between the parallels of 65 and 80. (See page 544.) From this life thermometer we learn only of warm or temperate seas. PALEOZOIC TIME DEVONIAN. 575 DEVONIAN ERA. SYNONYMY. Old Red Sandstone Series (from the rocks in Scotland), British Geologists before 1839. Devonian system, Sedgwick and Murchison, in a paper on the Classification of the older rocks of Devonshire and Cornwall, Ann. Phil, April, 1839. Old Red Sand- stone, or Devonian system, Lyell, Elements of GeoL, 1841. Devonian, of later geologists, Systeme Devonien, or Pe'riode Devonienne, Beudant, D'Orbigny, Lapparent. Devonische Formation, of the Germans. Devonic, International Congress of Geologists. As the era of the Upper Silurian passed quietly into that of the Devonian, no mountain range marks the interval between them, and no abrupt transition is apparent in the rocks or in the world's fauna. The Devonian was emi- nently a transition era as regards land vegetation, but the culminant time of aquatic Vertebrates Fishes. The land population was low grade, it com- prising only Myriapods, Spiders with the related Scorpions, and Insects ; and not the higher Insects, since there were no conspicuous flowers over the land. Terrestrial Mollusks also may have been in existence, but evidence of this has not yet been reported. The Devonian seas contained, in general, similar Invertebrate forms to those of the Silurian, but with proportionally fewer Trilobites, a profusion of Corals and Brachiopods, along with new forms of Cephalopods in the Goniatites and related species. NORTH AMERICAN. GENERAL FEATURES OF THE CONTINENT. The map of North America, representing its condition at the commence- ment of the Upper Silurian, gives a good general idea, so far as has been learned, of the continental seas and land at the opening of the Devonian era. There is the same uncertainty, or error, it may be called, with regard to the emerging lands over the Western Interior and Rocky Mountain region; the map fails to indicate them, because the limits of such areas have not been fully ascertained. These limits will in part always remain in doubt, unless deter- mined by deep borings; because absence of formations from the region of outcrops about Archaean mountains is far from being proof of absence beneath the plains between the mountains, or 50 miles or so distant from the mountains. It is, however, almost certain that in the Devonian era the Silurian island, covering much of Missouri, extended southward and westward over a large part of Arkansas and Texas, and beyond, as referred to on page 537. The Silurian islands of Tennessee and the Cincinnati region (C and T on the map, page 536) were still islands. A marked feature of the Continental seas is the half-confined Northeast Bay, of the Eastern Interior; and it has special importance in this era, since a large part of the described Devonian beds were deposited within it and owe to its varying conditions their charac- teristics. 576 HISTORICAL GEOLOGY. UPPER, OR LATER DEVONIAN. SUBDIVISIONS. {2. CHEMUNG EPOCH : that of the Chenrnng group, N. Y. Geol Reports, 1842, 1843. 1. PORTAGE EPOCH : that of the Portage group, N. Y. Geol Reports, 1842, 1843. 2. HAMILTON EPOCH: that of the Hamilton beds with the Tully limestone in places at top, N. Y Geol. Reports, 1842, 1843. 1. MARCELLUS EPOCH : that of the Marcellus shales (with the Goniatite limestone near the bottom), N. Y Geol. Reports, 1842, 1843. 2. CORNIFEROUS EPOCH : that of the Cornif- erous and Onondaga limestones, N. Y. Geol. Re- ports, 1842, 1843. 1. SCHOHARIE EPOCH: that of the Schoharie grit and Cauda-galli grit, N. Y Geol. Reports, 1842, 1843. That of the Oriskany sandstone, N. Y. Geol. MIDDLE DEVONIAN. 3. Hamilton Period. LOWER, OR EARLY DEVONIAN. 2. Cornife- 1 rous Period. | 1. Oriskany J Period : | The Devonian formations commence in eastern North America with sandstones. Then follows a great continental limestone, the Corniferous. This limestone has in the Devonian era, therefore, a position corresponding with that of the Niagara limestone in the Later Silurian. Above the lime- stone there is a great thickness of shales and sandstones with but little lime- stone. To the eastward, in New York and Pennsylvania especially, the sea border deposits of coarse sands, gravel, and pebble beds, of great thickness, which were in progress during the Upper and partly the Middle Devonian, make now red sandstone and conglomerate, and constitute what is called the Catskill formation. These beds have been heretofore regarded as mainly of subsequent origin to the Chemung, and have been referred to a period follow- ing it, called the Catskill period; but, as explained beyond, they are now believed to be a cotemporaneous formation parallel in its deposition with that of the off-shore and deeper waters of the Chemung period, or Chemung and Hamilton periods, to the westward. Over the Eastern Interior region limestones constitute the chief part of the beds of the earlier half of the era, and black shale, of moderate thickness, those of the later beds. The three divisions of the Devonian, the Early, Middle, and Later, have been named by H. S. Williams (1894), respectively, the Eodevonian, Meso- devonian, and Neodevonian. The term Erian is applied to the Devonian of North America by iawson. PALEOZOIC TIME DEVONIAN. 577 1. ORISKANY PERIOD. ROCKS KINDS AND DISTRIBUTION. The Oriskany sandstone in eastern North America has nearly the limits and distribution of the Lower Helderberg formation. It occurs over the eastern half of New York, between Cayuga Lake and Albany, and reaches northward to Oriskany Falls, northeast of Utica, having a thickness seldom exceeding 20 or 25 feet. It overlies the Lower Helderberg in Becrafts Mountain, and abounds in fossils. It extends southward along the Appalachian region, with increasing thickness, being 200 feet or more at Port Jervis, 150 to 200 feet along the western border of New Jersey, and eastern of Pennsylvania, and of still greater thickness in western Maryland (at Cumberland), West Virginia, and Virginia. It occurs also in eastern Canada, at Gaspe, and in Maine along the Gaspe-Worcester trough, over Parlin Pond and the northern part of Moosehead Lake, where it is reported to be several thousand feet thick (C. H. Hitchcock). It is found also in Ontario, west of Niagara, and in southern Illinois, where, in Union and adjoining counties, its maximum thickness is 250 feet. The rock is usually a rough calcareous sandstone, or arenaceous limestone, becoming, where weathered, porous and full of holes, from the dissolving away of its many fossils by percolating waters. It is sometimes cherty lime- stone, a pebbly sandstone, and in part a shale. In its distribution, its great abundance of fossils, and its usually calcareous or semi-calcareous character, it is widely different from the grits which follow it, and bears a close relation to the Lower Helderberg series of impure limestones. At Becrafts Mountain the beds represent the Lower Oriskany, and the rock is a hard, cherty, arenaceous limestone. A similar rock exists at Port Jervis. A sandstone containing what appear to be Oriskany fossils has been observed by C. W. Hayes in the highly disturbed region of northern Alabama, in Frog Mountain, between Weisner and Indian mountains. It rests on Lower Silurian and Cambrian unconf ormably ; but the unconformability, though extensive, is described as due to overlap. No intervening Upper Silurian beds occur in the region. The Clinton group (Kockwood beds) exists to the south, but not at that locality (1891, ? 94). The geological connections of the Oriskany are with the Lower Helder- berg formation, its beds thickening to the eastward as in the Lower Helder- berg. It is, however, pronounced Devonian in its fauna and flora, and hence belongs in the Devonian era. LIFE. The Oriskany fauna, although the rocks are rarely pure limestones. included a few Crinoids, of the genera Melocrinus, Mariacrinus, Technocrinus, Edriocrinus, etc. , common fossils in western Maryland, but not in New York ; some Cystoids; numerous Brachiopods, of which the two represented DANA'S MANUAL 37 578 HISTORICAL GEOLOGY. BBACHIOPODS. Figs. 848, a, Spirifer arenosus ; 849, Kensselseria ovoides. on this page are characteristic ; among Gastropods, a dozen or more species of Platyceras; Conularim, one, C. lata, over five inches long; a few Ortho- cerata; Trilobites of 848 a 849. the genera Homa- lonotus, Dalmanites, and others. The Homalonotus major, of Whitfield, had a length exceeding 15 inches, and a breadth of 5 inches. Dal- manites dentatus, of Barrett, has the front ornamented with a range of large trian- gular teeth, and is the earliest species of this type of Dal- manites. Acidaspis tuberculata occurs here and also in the Shaly limestone of the Lower Helderberg. With the close of the Oriskany period, the Lower Helderberg conditions of the Eastern Interior ended. The deposits no longer thickened to the eastward. Hall remarks on the close relation of the Oriskany fauna in central New York to that of the Lower Helderberg, but in other regions, especially in Ontario and Maryland, to that of the overlying Upper Helderberg. The true Oriskany sandstone or Hipparionyx fauna of New York comprises 45 species (Schuchert), which are chiefly large Brachiopods, Lamellibranchs, and Gastropods, with an almost total absence of Corals and Crustacea. In contrast with this, Beecher and Clarke have shown that the Lower Oriskany fauna of Becrafts Mountain and to the southward contains more than 120 species, of which 15 are Trilobites and about 10 are Corals, and the whole fauna is transitional, showing the pas- sage of the Lower Helderberg fauna into typical Lower Devonian. I. C. White concluded, from his observations in eastern Pennsylvania (1882), that the beds were accumulated on the borders of the seas in which the Lower Helderberg lime- stones were at the same time forming in clearer waters, thus making it one with them in period of origin. The beds of the latter often pass directly into the Oriskany, as if they constituted it. In Virginia there is the same close relation to the Lower Helder- berg. It is to be observed, on the other hand, that the beds of Becrafts Mountain overlie those of the Lower Helderberg. At the Delaware Water Gap the rock is largely a shale ; in Maryland, a crumbling sandstone, from loss of its calcareous part ; at Gaspe" , a limestone, with probably a part of the underlying sandstone beds, a Eensselceria having been found 1100' above the base of the sandstones. Oriskany fossils are reported also from the head of Tobique River in New Brunswick. The Nova Scotia strata of this epoch occur at Nictaux and on Moose and Bear rivers. They include a thick band of fossiliferous iron ore, which is an argillaceous deposit at Nictaux, but, owing to partial metamorphism, is magnetic iron ore, and partly specular, on Moose River. The Oriskany beds of New York are described in the N. Y. Geol. Sep. of Vanuxem and Hall, in Hall's Pal. jRep., vols. iii. and iv. ; by PALEOZOIC TIME DEVONIAN. 579 Beecher and Clarke in the Am. Jour. Sc., 1892 ; of eastern Pennsylvania, by I. C. White in Penn. Geol. Hep., G 6, 1882 ; of Illinois, in the Geol. Hep., 111., by Worthen, vol. iii. ; of Canada, in Can. Geol. Rep., 1863, and also in later Annual Reports. Among the Brachiopods of the Oriskany occur the genera Orthis, Stropheodonta, Leptcena, Hafines- quina, Chonetes, Leptostrophia, Meristella, Cyrtina, Spirifer, Hhynchonella, Centronella, Cryptonella ; also the genera Hensselceria, Eatonia, Leptocoelia, which are more largely developed in the Oriskany than in any other period. Orthis hipparionyx = Hipparionyx proximus, /Spirifer arenosus, S. arrectus, Leptoccelia flabellites, Cyrtina rostrata, Eens- selceria ovoides are characteristic species. The Illinois beds, of cherty limestone, have afforded Anoplia nucleata, Hhynchonella speciosa, Eatonia peculiaris, Leptoccelia flabellites, Newberria Condoni, Amphigenia elongata, Strophostylus ? cancellatus, Platyceras spirale, and other species. At Becrafts Mountain, the species include, according to C. E. Beecher and J. M. Clarke, six species of Dalmanites, two of Phacops, a Homalonotus, Cyphasphis, Proetus, Acidaspis ; a Cirriped of the genus Turrilepas; corals of the genera Zaphrentis, Homingeria, the Crinoid Edriocrinus sacculus. The unusual number of Trilobites for the Oriskany indicates apparently clearer waters along the Hudson River valley than to the westward along central New York. The Lower Helderberg species obtained are Acidaspis tuberculata of the Shaly limestone, a Cyphaspis, two Dalmanites, and a Phacops of L. H. type ; Tentacu- lites elongatus / Orthis perelegans, and O. oblata ? of the Shaly limestone ; Leptostrophia Becki, Trematospira multistriata, of the Shaly ; a Ccelospira, Anastrophia ; Eatonia medialis, of the Shaly ; a Zaphrentis, Shaly in type. The Devonian forms are Dalmanites phacoptyx (known previously only from .the Upper Helderberg of Ontario), a Phacops, Leptostrophia perplana, a Chonetes ?, Hemitrypa ?, Fenestella celsipora of the Corniferous. At Parlin Pond, in western Maine, there occur Hensselceria ovoides, Lepto- ccelia flabellites, Spirifer arrectus H., S. pyxidatus H., Stropheodonta magniflca H., Hhyn- chonella oblata H., Orthis musculosa H., Dalmanites pleuropteryx, etc. (Billings). See, further, on the relations of the Lower Helderberg, Oriskany, and Devonian faunas, the remarks on page 569. 2. CORNIFEROUS PERIOD. The Corniferous period includes two epochs, the SCHOHARIE and the CORNIFEROUS. To the former belong the Cauda-galli grit and the Schoharie grit, now considered cotemporaneous formations; to the latter, the Cor- niferous limestone. ROCKS KINDS AND DISTRIBUTION. The rocks of the Corniferous period in New York have their greatest thickness in the region of the Eastern Interior Sea, along the Appalachian belt. The Cauda-galli grit, a dark gritty slate, thickens toward the Hudson, being 50 or 60 feet thick in the Helderberg mountains, and 100 to 150 feet east of the Hudson Eiver in Becrafts Mountain, near Hudson ; and the Schoharie grit is best displayed in the eastern counties of New York, Albany, Greene, and Schoharie. Neither formation is found to extend far west over the Oriskany beds of western New York and Ontario. The Cauda-galli, like many seashore deposits, is almost destitute of fossils ; but the Schoharie beds abound in them, and they are closely related to those of the following Corniferous epoch. The Corniferous limestone so called by Eaton, with reference to the hornstone or flint often imbedded in it (from the Latin comu, horn) extends 580 HISTORICAL GEOLOGY. from near the Hudson in eastern New York, westward through the state, and at the Niagara River forms the rapids at Black Bock. Thence, it is con- tinued westward through Ontario to Ohio, across northern Ohio, and to Mackinac in northern Michigan. It thus passes beyond the limits of the Eastern Interior Sea into the Central Interior, where it is widely distributed, occurring in Indiana ; in great force at the Falls of the Ohio, just east of New Albany and Louisville ; also in Illinois and Kentucky ; in eastern Iowa, near Davenport, as a bed of gray to buff limestone 150 feet thick, resting on Niagara and Trenton; and in Missouri. The limestone is commonly light gray to bluish or buff (lightest, which means purest, to the west) ; occasionally it is blackish and rough from the abundance of hornstone masses, which are left projecting by surface wear. Much of the rock abounds in corals, like many reef-rocks of modern coral seas. It exhibits its coral-reef character grandly at the Falls of the Ohio, where the corals are crowded together in great numbers, some standing as they grew, others lying in fragments, as they were broken and heaped up by the waves, branching forms of large and small size mingled with massive kinds of hemispherical and other shapes. Some of the cup corals (Cyathophylloids) are six or seven inches across at top, indicating a coral animal seven or eight inches in diameter. Hemispherical compound corals occur five or six feet in diameter. The various coral-polyps of the era had, beyond doubt, bright and varied coloring, like those of the existing tropics ;. and the reefs were therefore an almost interminable flower-garden. In the Canada-New-England region a limestone made up of corals occurs on Lake Memphremagog, between Vermont and Canada, showing that coral reefs flourished there also ; and other localities exist to the eastward. At Gaspe, a thick limestone formation underlies 7036 feet of Devonian sand- stone ; and about 800 feet of the limestone with 1000 feet or so of the overlying sandstones are referred to the Corniferous period. Over the western part of the Continental Interior, beyond the Mississippi, at Paleozoic outcrops, the Carboniferous beds often rest directly on the Lower Silurian, or the Cambrian, with nothing of the Devonian between. This is so at the Black Hills, in Dakota, and in central Texas, and east of the Front Eange, in Colorado. Farther west, in the Eureka district, there are 6000 feet of Devonian limestone (Hague). In the Wasatch Mountains the Devonian is made by King 2400 feet thick, the lower 1000 feet consisting of the "Ogden quartzyte," and the part above this being the lower portion of the " Wasatch limestone," whose total thickness is 7000 feet. Just north of Montana, in British America, there are 1500 feet of Devonian limestone. In California, Devonian limestone and shales occur east of the Sacra- mento in Siskiyou and Shasta Counties (Diller and Schuchert). In the northern part of British America Devonian rocks occur along the Mackenzie River (F. B. Meek, from the collection of R. Kennicutt) ; but the fossils yet observed are those only of the Hamilton and later Devonian, PALEOZOIC TIME DEVONIAN. 581 so that the presence of Corniferous rocks is doubtful. The recent map of the Canadian survey makes a Devonian belt (with Carboniferous beds) to come down from the far north, along by the summit of the Rocky Mountains, into the United States. The Corniferous limestone in some places abounds in mineral oil. The oil wells of Enniskillen, western Canada, are from this rock, according to T. S. Hunt (1863) ; large areas are covered with the inspissated bitumen. At Eainham, Canada, on Lake Erie, shells of Pentamerella arata are some- times rilled with the oil ; and in other localities Corals of the genera Hellopliyllum and Favosites have their cells full, in some layers of the limestone, while empty in other layers. The facts, with regard to the distribution of the Devonian formations in North America, the history of geological discovery in connection with them, their geological relations and distinctive features, are clearly and fully presented by H. S. Williams, in Bulletin No. 80 of the U. S. Geol. Survey, and partly from personal observation. Interior Continental and Appalachian region. The Cauda-galli grit in New York is a drab or brownish argillaceous sandstone, often shaly and crumbling. From eastern New York it continues along the northwestern boundary of New Jersey, and the eastern of Pennsylvania, where it is a gritty slate, and is in some places 400' to 500' thick. The Corniferous limestone in New York consists of two members, the gray Onondaga limestone, or lower part, and the darker Corniferous, or upper. But the two alternate with one another, and no distinction is now recognized. The limestone is sometimes oolytic. Its thickness, as found where boring for oil and salt, is commonly 100' to 160'; at Ithaca only 78'. Along the Delaware, south of Port Jervis, N.Y., to the New Jersey boundary, the thickness is about 250' ; the flint nodules are from an inch to a foot in diameter, and often contain shells and remains of Crinoids. In Ohio it occurs on both sides of the Cincinnati geanticline, and also along the shores of Lake Erie. On Kelleys and Middle islands, in this lake, the beds have the characters of old coral reefs, like those at the Falls of the Ohio. It corresponds, it is supposed, to the whole Upper Helderberg period ; two divisions are made out, the lower, named the Columbus, or Sandusky, and the upper, the Delaware limestone. In Missouri, siliceous and sandstone layers alternate with the limestone. Rocky Mountain and Pacific border regions. In the Eureka district, the thickness, according to A. Hague, is 8000' ; the lower, 6000', limestone (see page 592) ; and the rest, shales. Lower Devonian fossils exist in the lower part for at least 500', and Upper, in the upper portion ; but no subdivisions could be marked off. The Eureka district appears, therefore, to be the center of one of the extra thick Devonian basins, like those of the Appalachian region, and Gaspe of eastern Canada, on the St. Lawrence Gulf. How far south or north the thick beds continue is not known. To the north, in the Tucubit Mountains, Devonian occurs. In Arizona, in the Kanab Canon (1121 W.), the whole Devonian is only 100' thick (Walcott). In the Wasatch region, the " Ogden quartzyte " is referred to the Devonian, by King, who found it at Ogden Canon 1200' to 1400' thick, at Cotton wood Canon 1000', and at some points in Middle Nevada 800' to 900'. In the Wasatch Mountains, the lower 1400' or more of the overlying Wasatch limestone (7000' thick) is Devonian, it affording fossils of the Upper Helderberg, Genesee, and Chemung. See King, Geol. 40th Par., page 236. In the Laramide range of the southern part of British America occur 1500' of Devonian limestone (McConnell). 582 HISTORICAL GEOLOGY. LIFE. PLANTS. Among Algae, or Seaweeds, the most remarkable is the Spi- rophyton Caudagalli. Fig. 850 represents a fragment of the plant. The broad blade of the seaweed grows spirally about the central axis, much like that of the erect Alaska seaweed, Thalassophyllum clathrus. The Nema- tophyton (Dawsoii), Fig. 851, is a tree-like Fucoid. The specimen was found in the lower part of the Devonian of Gaspe, Canada, where the stems are 852. Fig. 850, Spirophyton Caudagalli ; 851, Nematophyton Logani (x|) ; 852 o, 6, c, fruit of Charse? Figs, from Hall, Dawson, and Knowlton. sometimes three feet in diameter. The presence of Charce, water-plants of simple cellular structure (inferior to Mosses, but Equiseta-like in habit, and now common in marshy places), has been rendered probable by the discovery (first made by F. B. Meek) of minute calcareous fossils resembling their fruit (spore-cases) (Figs. 852 a, b, c,), in the Corniferous limestone of Ohio, and in the cellular chert at the Falls of the Ohio, near Louisville. The hornstone, or chert, in the Corniferous limestone, as shown by M. C. White, is full of microscopic plants from -^-^ to -^ of an inch in diameter ; and with them occur sponge-spicules and teeth of Annelids. Fig. 853 : a to e are Xanthidia, spore-cases of Desmids (page 437) ; /, g, conferva-like filaments, made of a series of cells ; i, a Diatom. Besides these there are siliceous spicules of sponges, Figs, j, Jc, I, m, n; and o, p represent portions of jaws of Annelids. The mass of the hornstone was probably made out of siliceous sponge-spicules and Diatoms. PALEOZOIC TIME DEVONIAN. >83 The higher Cryptogams, or Acrogens, are represented by Lycopods, or Ground Pines, Ferns, and Equiseta. To the Lycopod tribe are referred species of PsUophyton, similar to those of the Oriskany period ; portions of the plant are shown in Figs. 854 a, 6, and 853. MICROSCOPIC ORGANISMS IN HORNSTONE. Figs, o-i, Protophytes ; j-n, spicules of Sponges ; o, p, Annelid jaws. its fructification in c, d. They were one to three feet high. The species differ from the common Ground Pine in having the leaves on the stems nearly wanting, and also in having the axis made up of scalariform vessels, and the spore-cases (fruit, c, d) usually in pairs on short pedicels. 854-857. 855 -04 LYCOPODS. Figs. 854 a, 6, Psilophyton princeps ; c, d, same, fruit ; 855 a, Lepidodendron Gaspianum (1) ; 6, same, showing surface scars of lower part of stem. FERNS. Fig. 856, Sphenophyllum vetustum (1) ; 857, stem of tree fern, Caulopteris antiqua (x J). Figs. 854, 855, Dawson ; 856, 857, Newberry. The Corniferous limestone of Ohio has afforded the Ferns, Figs. 856 and 857, described by Newberry. The latter is part of the trunk of a tree fern 584 HISTORICAL GEOLOGY. of the genus Caulopteris ; and G. advena Newb. is the name of another species. The trunks of both are three to four inches in diameter. Newberry states that these tree ferns probably grew over the region of the Cincinnati uplift then an island (C, map, page 412 or 536). Spores and spore-cases (sporangites) have been reported from the lime- stone of Ontario County, N.Y. As described by J. M. Clarke they are -^^ and -$ of an inch in diameter ; he suggests that they may be from Rhizocarps (the lowest of Acrogens) of the genus JSalvinia (p. 436), and they are referred to the species Protosalvinia Huronensis of Dawson. ANIMALS. The Upper Helderberg period was eminently, as has been stated, a coral-reef period, but besides corals, it abounded also in species of other tribes of invertebrate life characteristic of Paleozoic time. 1. Sponges. The existence of Sponges is indicated by the presence of their siliceous spicules in the hornstone, two slender forms of which are shown in Figs. 853 j, Jc, and others in I, m, n. Besides, there are species of Astrceospongia and Hindia. There are also several species of Stromatopora, and the last known in America of Receptaculites. 858-864. POLYPS. Fig. 858, Zaphrentis gigantea; 859, Z. Rafinesquii ; 860, Phillipsastrea Verneuili ; 861, 861 a, Cyatko- phyllum rugosum ; 862, Favosites Goldfussi ; 863, Syringopora Maclurii ; 864, Romingeria cornuta. Figs. 858, 860, 862, Edwards and Haime ; 859, 861, Meek ; 863, Yandell and Shumard ; 864, Billings. 2. Polyp-corals. Figs. 858 to 864 represent a few of the many Corals: 859 shows the radiated cup-shaped termination to which the name Cyatlw- phylloid (from *ua0os cup, and ., xxiv., 1882 (on Turrilepas). Dithyrocaris Belli Woodw. (Geol. Mag., 1871) is from Gaspe". Some of the characteristic Marcellus fossils are : Productella truncata H., Orbiculoidea minuta H., Leiorhynchus limitare H., Chonetes mucronatus H., Leiopteria Icevis H., Pleu- rotomaria virgulata H., Styliolina fissurella H., Orthoceras subulatum H. The Iowa Hamilton has afforded species of Megistocrinus, Taxocrinus. Synbatho- crinus, Pentremites ; Orthis suborbicularis H., O. Vanuxemi H., 0. lowensis, 0. ince- qualis, 0. prava, Stropheodonta arcuata H., S. nacrea H., S. reversa H., S. demissa, S. perplana, Productus dissimilis H., Productella pyxidata H., P. subalata H., Productus Shumardianus H., Spirifer Hungerfordi, S. Whitneyi H., S. fimbriatus Con., 8. bimesia- lis H., S. asper H., S. Parryanus H., S.pennatus Owen, S. Marionensis Shumard, Cyrtina umbonata H., C. triquetra H., Gypidula occidentalis H., Atrypa aspera, A. reticularis, Euomphalus cyclostomus H. 4. CHEMUNG PERIOD, OR LATER DEVONIAN. ROCKS KINDS AND DISTRIBUTION. The Chernung Period includes (1) the PORTAGE epoch, represented by the Genesee shale below, and the true Portage group above ; and (2) the CHEMUNG epoch. The Catskill group, which has usually been made to repre- sent a third epoch, is mainly, as stated on page 576, the sea-border part of the Upper Devonian. The Genesee shale, at the base of the Portage, is black and bituminous, like the Marcellus shale, and rather sparingly fossiliferous. It is 100 to 150 feet thick in central New York, along Cayuga Lake, where it overlies. PALEOZOIC TIME DEVONIAN. 60S the Tully limestone, and 25 feet on Lake Erie, and 200 to 300 in west central Pennsylvania. Along one or two levels there are great numbers of large and small calcareous concretions which are often septate (page 97), so as to make the concretions look a little like the backs of turtles. In western New York a layer of bituminous limestone, six inches to two feet thick, occurs near the middle, which is mostly made up of shells of a Pteropod, the Styliolina fissurella Hall (Fig. 916), and is called the Styliolina lime- stone. With it occur remains of fossil fishes, Dinichthys, Palceoniscus, and other species. The Portage group, of New York (so named from the village of Portage, Livingston County, N.Y.), outcrops along a wide belt extending eastward from the south shore of Lake Erie. It is well displayed about the south end of Cayuga and Seneca lakes. Its beds are shales and flags, or shaly sandstones, the Naples group, and, above these, the Portage sandstone, which has relations to the Chemung. The rocks have a thickness of 1000 feet on the Genesee River, and 1300 to 1400 near Lake Erie. The rocks are in general very sparingly fossiliferous. They abound in ripple-marks and mud-cracks, and the sandstones are often cross-bedded. But a portion in central New York, called the Ithaca group, prominently displayed on the Cascadilla and Fall creeks, near Ithaca, abounds in fossils. According to H. S. Williams, the fossils, which are largely Brachiopods, have near relations to those of the Chemung group, and also about as close to Hamilton species ; and as they are overlaid by 5QO or 600 feet of sandstones, mostly barren, but containing some Portage species, they are referred to the Portage group. They are the only part of the beds that give much knowledge of the life of the period ; and this is imperfect, as Trilobites, Corals, Crinoids, and other species of purer waters, are absent. In eastern central New York, in Delaware, Otsego, and Chemung counties, there is a sandstone formation, the Oneonta sandstone of Vanuxem, which resembles the Catskill beds ; but it is overlaid by beds containing Portage fossils ; and in some places, Chemung species. It indicates the existence, at these localities, of Catskill conditions during the Portage and Chemung epochs, if not also during part of the Hamilton period. (H. S. Williams.) On the distribution of the Oneonta beds, see Darton, Am. Jour. Sc., 1893. In central and western Pennsylvania the limit between the Portage and Chemung is not clearly ascertained. The thickness of the two in Monroe County, eastern Pennsylvania, is about 2500 feet ; Fulton County, south central Pennsylvania, about 3600 feet, of which 400 are referred to the Portage. Along the south shore of Lake Erie, the lower part of the " Ohio shales " is referred to the Portage, and the rest to the Chemung. Near Cleveland, 0., the thickness of the " Ohio shales " is about 1350 feet, and farther west, at Elyria, 950 ; but at Wellsville on the Ohio, 2600 feet. The Chemung beds in New York are a continuation of the Portage, with little change in the rocks, except that they are slightly more arenaceous, and of a lighter color, but with a great change in the abundance of fossils and 604 HISTORICAL GEOLOGY. in their kinds. They cover a large part of southern and western New York. The layers bear the same evidences of shallow waters as the Portage, and are often cross-bedded from the sweep of the currents of probably the tidal ebb and flow. The thickness south of Cayuga Lake is stated at 1500 feet, and in Chautauqua County, bordering Lake Erie, 950 feet. At Panama, in this county, about a dozen miles from the western border of New York, the Chemung rock is a hard, quartzose " flat-pebble " conglomerate, its pebbles, which are mostly of quartz, being commonly flat. The rock near Panama stands up in bold bluffs and walls, with intersecting passages and isolated towers, making the place one of the so-called " Kock-cities " of western New York. The conglomerate is 200 to 300 feet below the top of the fossiliferous Chemung of that region. The rocks dip southward gently, and in the north- western counties of Pennsylvania are succeeded by the shales and sandstones of the Waverly group containing a different fauna. The thickness of the group is greater over northern and central Pennsyl- vania, along the Appalachian area, becoming 2000 to 8000 feet ; but, like the Portage, it diminishes rapidly westward, where it passes outside of this area. The Upper Devonian is represented over the larger part of the Central Continental Interior by a "Black shale," a stratum 10 to 200 feet thick, carbonaceous, but not always black. At Burlington, Iowa, it includes some limestone. It indicates nearly uniform conditions of level over a great extent of surface, but with variations only between salt or brackish and fresh waters. Its fossils are mainly small Brachiopods, Ceratiocarids, and Fishes. The Catskill group so named from the Catskill Mountains of eastern New York consists of sandstones, often passing into conglomerates, with some shale. The beds are usually red, but occur also of greenish and other shades. They are rarely fossiliferous; and the few animal fossils found are those of Fishes, Eurypterids, and some fresh-water Lamellibranchs. A prevailing red color, and no marine fossils, are its accepted characteristics ; but these are poor criteria for separation chronologically from the Chemung. Hall was the first to show that they were in part Chemung. H. S. Williams has recently referred the whole to the Upper and Middle Devonian, and speaks thus of its relation in position over the state of New York to the rocks of these periods : " In the G-enesee section in western New York, the whole of Devonian time is recorded without any trace of the Catskill formation ; it is neither above, below, nor within the Chemung. One hundred miles eastward, the section running through Cayuga Lake shows at the close of the Devonian, after the cessation of the Chemung fauna, a Catskill formation several hundred feet thick. Another hundred miles eastward, across Otsego County, the section contains (1) rocks of the Catskill formation for the upper third of the Upper Devonian; below these (2) a sparsely fossiliferous zone of Chemung probably its lower part, and (3) a modified Ithaca fauna; then (4) the Oneonta formation, which is but a detached zone of the Catskill; next (5) a fauna intermediate between that of the Ithaca and the typical Hamilton, underlaid by (6) the Hamilton formation of the PALEOZOIC TIME DEVONIAN. 605 Middle Devonian. Still farther east, along the Hudson Eiver valley, the Catskill formation occupies the whole of the Upper Devonian interval." The beds show that the region of their depositions was invaded here and there at times by fresh waters from the bordering hills. In the Catskill Mountain region the Catskill rocks are to a large extent the summit rocks and have a thickness there of 3000 feet. Marking them, as is usual, by their coarse sandstone character and red color, they extend southwestward into Pennsylvania, along the course of the Appalachian trough, from Port Jervis, N.Y., to Fulton County, and have a reported thickness, in this part of the state, of 4500 to 7000 feet ; 3430 at Port Jervis, 4000 to 5300 in Monroe County, Pa., 7544 near Mauch Chunk, 6000 in Perry County, and 3900 in Fulton County. In Fulton County, Chemung fossils have been observed in the so-called Catskill beds by J. J. Stevenson, through the lower 900 feet, reducing the thickness of the so-called Catskills at that point to 3000 feet. West of the above-mentioned line, the reported thickness diminishes; in southwestern Bedford County, it being bat 2000 feet, and only a few feet in western Somerset County. Eastern New York and Pennsylvania continued to be for a long time a sea- border region, undergoing the subsidence required for thousands of feet of sea- shore deposits, because here lay the border of the Appalachian geosyncline. The Portage group was early called the Nunda group, from this early name of the village of Portage, situated on the banks of the Genesee River, where the beds occur. The Genesee shale is finely displayed at the opening of the gorge of the Genesee at Mount Morris ; and it also forms high cliffs above the Tully limestone along the borders of Cayuga and Seneca lakes. The concretions occurring in the rocks sometimes contain min- eral oil, and a soft substance looking like spermaceti. The region of the Portage beds in New York is famous for its waterfalls. On the Genesee River, the group includes, above the Genesee shale, (1) the Cashaqua shale, and the Gardeau shale and sandstones, the Naples beds of J. M. Clarke ; and (2) the Portage sandstones. The Portage beds of western Pennsylvania are so deeply buried that their thickness is unknown ; the drillings for oil do not reach down to them. The Ithaca group abounds in ripple-marks, mud-cracks, calcareous concretions, and cone-in-cone forms. It is referred by Hall to the Chemung series. Prosser has deduced from the many drillings in western New York, and the observa- tions of Hall, H. S. Williams, and others, the following section for the region not far west of the Genesee River, near Rochester : Feet Feet Wolf Creek Conglomerate . 300 Salina? (to 4000' d.) ... 600 Chemung (to 1450' depth) . 1150 Niagara and Clinton ... 250 Portage ........ 900 Medina ........ 1158 Genesee shale ...... 100 Hudson, Utica ..... 598 Hamilton (to 3200' d.) . . - 750 Trenton (to 6960' d.) ... 954 Marcellus shale ..... 50 Calcif erous ? (to Archaean ?) . 137 Corniferous Lower Helderberg? 1 . . . . / In Pennsylvania, in Perry County, the Chemung is 3300' thick, and the Catskill 6000' (Claypole) ; but the latter contains in its lower third some Chemung fossils. In Columbia 606 HISTORICAL GEOLOGY. County, where the Catskill is made 4500' thick, 2300' to 2443' are referred to the Cheraung and Portage (I. C. White). Above lies a transition Catskill-Chemung group of 1000', regarded as transitional because they are so in color, and contain some Chemung fossils ; and to the west, the true Catskill group wholly disappears ; that is, the rocks have nothing of the Catskill characteristics. In Prosser's section in Monroe County, Pa., referred to on page 594, he found the beds to correspond to the Portage, Oneonta, and Chemung, through a thickness of 3050', and to include the Chemung beds of White, and the overlying Starucca sandstone, 600', New Milford shales, 100', and the Delaware flags, 1200'. Above come the Montrose shales and the so-called Catskill beds, the last consisting of the Honesdale sandstone, the Cherry Ridge group, 325', the Elk Mountain sandstone and shale, 200', and the Mount Pleasant, 1150', Red shale, 300' ; about 2000' in all. The "Black shale" of the Central Interior occurs in Indiana, at the Falls of the Ohio, with Genesee shale fossils at its base ; in Kentucky, 200' thick in the northeast part, and diminishing southwestward. In Illinois it is 40' to 60' thick, the thickest along the Ohio ; it contains a Genesee Lingula. In Tennessee, through much of the state, it is 100' thick and less. Owing to denudation, it is not found in central Tennessee. In Ar- kansas and Missouri, its equivalent, the Eureka shale, is 0' to 50' thick. In Ohio, the Ohio shales include the Cleveland shale, Erie shale, and Huron shale of Newberry ; a belt of it, 10 to 20 miles wide, and several hundred feet thick, stretches across Ohio from Lake Erie to the Ohio Valley, and is noted for its calcareous and ferruginous concretions ; the lower part corresponds to the Huron shale, and the upper beds to the Cleveland shale. At its base, or directly below it, Hamilton fossils have been found ; but above, a few Portage and Chemung species. The Cleveland shale has afforded many remains of Fishes. The Perry sandstones of southern New Brunswick are .mentioned on page 594. The yellow sandstone at Pine Cove, Muscatine County, Iowa, and the Ro'ckford shale "belong near the base of the Chemung. In a paper by Darton (1893) it is proposed to adopt the name Catskill for the period including the Chemung and Portage. But, as has been shown, it has not the fossils that would entitle it to such a position. In fact, the name Catskill has no right to a place in the time series. Its introduction was from the first an error. In the Arctic regions, on the eastern part of the north coast of Grinnell Land, at Dana Bay, occurs an area of rocks containing Productus mesolobus or costatus, a Spirifer, etc., which are referred by the authors to Devonian (Feilden & De Ranee, Q. J. G. $., xxxiv., 1878) ; but these fossils are Carboniferous. An interesting excursion in eastern New York, for the study of the Devonian series, may be had by going to Catskill Village, and passing westward over the hills at the base of the Catskill Mountains. Over the Hudson River slates lies the water-lime of the Middle Upper Silurian ; then the successive subdivisions of the Lower Helderberg. Beyond lies the Corniferous limestone of the Lower Devonian ; then the Marcellus shale and Hamilton sandstones. Moreover, the flexures of the rocks are instructive. See W. M. Davis on the Little Mountains, Appalachia, 1882, page 20. Rondout, N.Y., on the Hudson River, affords a section from the Hudson beds to the Corniferous inclusive, part quite fossiliferous, and the line of a great fault above the Hudson beds, and is another good place for the geological student. See W. M. Davis, Am. Jour. 8c., 1883, vol. xxvi. The Devonian series of the Pahranagat Range, central Nevada, is 3000' thick, and is fossiliferous. It ~ests on the Silurian. For notes on the Upper Devonian of the Eureka district, see pages 589, 592. Mineral oil and gas. The upper part of the Upper Devonian is the -chief source of the mineral oil and gas of Pennsylvania. The drillings PALEOZOIC TIME DEVONIAN. 607 descend to a coarse oil-yielding porous sandstone called an oil-sand; and on reaching it, the oil, if the well is successful, usually rises to, or above, the surface ; or if a gas well, the gas comes out with great force. The number of different oil-sands in a region is one to three; they are confined to about 300 feet in thickness of the beds, and each is 20 to 60 feet, or more, thick. The productive counties lie in a belt, nearly northeastward in course, from Greene County, in the southwest part of the state, to McKean County, on the northern border ; and they pass this border into Alleghany County, N. Y., and also on the south, into Monongalia County, W.Va. See map, page 731. In the counties from Warren to Washington the oil-sands are within 400 feet of the summit of the Devonian ; in the part of the belt more to the northeast, in McKean County, and in New York, they are in its lower part, or between 1200 and 1800 feet of the summit. The latter is a high region, the surface 1800 to 2600 feet above the sea level. The wells often let up much salt water from different levels. Frequently water rises with the oil or gas, making the well valueless unless tubing to the bottom will exclude the water. The oil-sands are coarse, open-textured sandstones so open in texture that they are able to hold a vast amount of oil in the spaces between the grains. All the oil-bearing regions are also gas-producing ; but the well is available for gas only when the latter comes to the surface free from oil as well as water. Moreover, the gas is abundant, according to I. C. White, only where the rocks passed through in the drilling lie in a low anticline. The open-textured sandstones are possibly sandstones that have lost the finer material between the grains by percolating waters. As some of the Chemung beds are more or less calcareous, they may originally have been calcareous sand-beds, and have become porous by the removal of the calcareous part ; but this is only conjecture. The oil is usually projected in jets, and the power has been shown to be Artesian, or hydrostatic, by I. C. White, in agreement with Orton's view for the Trenton limestone gas of Ohio and Indiana. A well near Kane, in McKean County, Pa., drilled to a depth of 2000 feet, in 1878, but abandoned because of the small yield of oil, became afterward a water-and-gas geyser, gas and not steam being the moving agent. Fig. 925 is from a photograph received in 1879 by the author from C. A. Ashburner, accompanying a description by him of the geyser. The well at that time threw up a column of water and gas, at intervals of 10 to 15 minutes, to heights varying from 100 to 150 feet. On August 2d four successive jets had heights of 108, 132, 120, and 138 feet. When the gas of the columns was lighted at night, "the antagonistic elements of fire and water were promiscuously blended, at one moment the flame being almost extinguished, but only to burst forth the next instant with increased energy and greater brilliancy." Mr. Ash- burner explains the action thus : " The water flows into the well on top of the gas until the pressure of the confined gas becomes greater than the weight of the superincumbent water, when an explosion takes place, and a column of water and gas is thrown to a great height." The gas comes 608 HISTORICAL GEOLOGY. 925 - from the deep-seated rock that has yielded also the oil, and some higher tem- perature than that of the surface was needed for its production. At a depth of 1415 feet in the drilling a very heavy "gas vein" was struck, and this was- the chief source of the gas. Ashburner remarks further that several other wells in the oil-regions have had similar gey- sers ; and as early as 1833, in the valley of the Ohio, a salt well threw jets of water and gas, at intervals of 10 to 12 hours, to heights of 50 to 100 feet. The original source of the oil is sup- posed, by most writers on the subject, to have been a Devonian shale, like the Genesee or Marcellus, below the level of the Chemung beds, from which it- was evolved by a slow process of distil- lation. The conditions necessary for oil, on this view, are (1) a primary source of the oil ; (2) strata to receive and hold it ; and (3) overlying deposits to prevent its escape to the surface and consequent dissipation. These three conditions are fulfilled by (1) a deep- seated carbonaceous rock containing abundant organic remains; (2) an over- ty in g porous stratum; and (3)super- incumbent shales, slates, etc. These statements also apply to gas production. Slight subterranean movements attending the making of the Appalachian Mountains to the east and south- east would have produced some heat, and so have caused oil to escape from the shales; and the .vaporized oils would have risen until they were some- where condensed either in confined places in or among the rocks, or still higher in the open air (Peckham, 1884). I. C. White regards the source as- organic materials within the sand-beds. -gas geysen The oil wells of western Pennsylvania yielded, in 1891, 31,793,477 barrels of the crude oil, or petroleum. Of this, 5,452,418 barrels were from the Bradford district, McKean County, and 10,317,258 from Alleghany County, the county of which Pittsburg is the capital. In the same year, the yield of Alleghany County, N.Y., adjoining the northern end of the Pennsylvania belt, was 1,121,574 barrels; and that of West Virginia, adjoining the southern end, 2,406,218 barrels. The total yield of the United States in 1891 was 54,291,980 barrels. Ohio produced 17,740,307 barrels, making the yield for Pennsylvania and Ohio together 49,533,784 barrels. But the oil of Ohio was nearly all from the Lower Silurian Trenton limestone this formation affording 17,316,000 barrels; the Berea grit,, which is referred to the Subcarboniferous, supplied only a few hundred thousand barrels- PALEOZOIC TIME DEVONIAN. 609 A barrel equals 42 gallons. The yield of Pennsylvania in 1859 was 2000 barrels ; in 1860, 500,000 barrels; in 1870, 5,260,234 barrels; in 1880, over 26,000,000 barrels. In 1892, the yield was over 4,000,000 barrels less than in 1891. For a report on the oil and gas regions of Pennsylvania, with maps, see Rep. I 5, of the Penn. Geol. Surv., by John F. Carll, 1890 ; and for Ohio, Rep. vol. vi., on Economic Geology, by E. Orton, 1888 ; and for Kentucky, Rep. by E. Orton, 1891 ; and for Statistics, Mineral Resources of the U. S., by D. T. Day, 8vo. ; U. S. G. S., volumes for 1891 and 1892, issued in!893. 926-930. 929. 927. 926. Fig. 926, Archaeopteris Halliana ; 927, A. minor ; 928, Aneimites obtusus ; 929, Sigillaria Vanuxemi ; 930, Lepl- dodendron Chemungense. Figs. 926, 930, Hall ; 927, 928, Lesquereux ; 929, Vanuxem. DANA'S MANUAL 39 610 HISTORICAL GEOLOGY. LIFE. PLANTS. In the Portage the remains of land plants are rare. There are stems of species of Lepidodendron L. Chemungense and L.primcevum; of Lycopodites and Knorria; of Cyclostigma C. affine Dn. ; of Calamites Bornia inornata Dn.; of Tree-ferns, Asterochlcena (Asteropteris) Noveboracensis Dn., from Milo, N.Y. ; and woods of Gymnosperms, as Cordaites (formerly Dadoxylon} Clarki Dn. Sporangites ($. Huronensis) occur in the more bitu- minous portions of the Genesee shale. 931. Dictyo-cordaites Lacoei, Dawson (1): a, venation of leaf ; 6, fruit enlarged. Dawson, '89. The Chemung land plants discovered include those of the Portage and others. Some of them are represented on page 609. Figs. 926, 927, 928 show portions of plants from the Chemung of Gilboa, K Y. ; 928, from the Catskill beds of Montrose, Pa. ; 929, from Pottsville, Pa., and Franklin, N.Y. The PALEOZOIC TIME DEVONIAN. 611 Pottsville specimen of Aneimites obtusus Lx. (Fig. 928) was over a foot across. A Tree-fern also, Caulopteris Lockwoodi Dn., has been obtained at Gilboa. Fig. 929 represents a Sigillaria from the Chemung of Owego, N.Y., and 930, a Lepidodendron from Elmira, N.Y., the latter with very small leaf-scars. In the specimen of Fig. 929, the upper part shows the scars as they appear on the inner surface of the bark. Specimens of L. Gaspianum, of the Lower Devonian, and some other species, have also been found in the Chemung beds of New York ; and L. corrugatum of Dawson in the Chemung of Ohio, and also at the base of the Carboniferous near Pottsville, Pa., and in Vir- ginia. The Gaspe species accompanying the Pterichthys Canadensis, and indi- cating thereby that the beds are Upper Devonian (Dawson), are Archceopteris Gaspiensis Dn., Aneimites obtusus Lesq., and Rhacophyllum Broivnii Dn. Fig. 931 represents a remarkable plant from beds in Wyoming County, Pa., referred to the lower part of the Catskill series. Dawson regards it as belonging to the Cordaites group, under Gymnosperms. The fruit enlarged is shown at b. The black shales of the Upper Devonian in New York, Canada, Ohio, and elsewhere, like those of the Lower Devonian, abound in Sporangites (page 596). The facts show that the simple plants the Rhizocarps were, as Dawson states, very abundant in the waters. Dawson speaks of the spores as " dispersed in countless millions of tons through the Devonian shales of Canada and the United States," and as being the source of their black color and their oil-yielding character. ANIMALS. 1. Spongiozoans. The network hexactinellid Sponge, Dicty- ophyton tuberosum of Conrad, occurs in the Chemung, where there are also other species of the genus. Uphantcenia Chemungensis of Vanuxem is another peculiar glass Sponge of the Chemung, found near Owego, N.Y., first referred to the Sponges by Whitfield. 2. Corals and Crinoids. These are not common in the Portage or Chemung group. Some calcareous beds of the Chemung have afforded Corals of the geneva, Zaphrentis and Heliophyllum (near H. Halli of the Hamilton); also remains of Crinoids, showing that these animals were absent from the Upper Devonian only because the con- ditions of the New York and the bordering seas were unfavorable ; they were back when the seas were again of sufficient purity. 3. Molluscoids. Some of the few Genesee and Portage Brachiopods are represented in Figs. 933 to 936. In the lettering underneath the cut the letters G. SPONGE. Dictyophyton and P. are initials of Genesee and Portage. Besides tuberosum. the genera represented in the figures, Chonetes and Productella are also prominent. 932. 612 HISTORICAL GEOLOGY. Brachiopods were far more numerous in the Chemung beds than in the Portage. The figures 939 to 942 represent common species ; 941, an Atrypa of ornate type, like the young of A. reticularis; 940, a species of Productella. 933. 933-938. 934. BBAOHIOPODS. Fig. 933, Spirifer laevis (P.) ; 934, Leiorhyncus quadricostatum (G.) ; 935, Lingula spatulata, (x 3) (G.) ; 936, Orbiculoidea Lodensis, (x 2)(G.). LAMELLIBRANCHS. Fig. 937, Lunulicardium fragile (G. and P.); 938, Glyptocardia speciosa (G. and P.). Hall, except Fig. 934, King. 4. Mollusks. Lamellibranchs were few in the Portage, but very numerous in the New York and Pennsylvania Chemung beds, outnumbering all other Mollusks. Hall describes 252 Chemung species, and only 11 from the Portage and Genesee beds, with 174 from the Hamilton. Figs. 939, 940, 943, 944, 945, represent some common forms. A compressed specimen of a New York Catskill species is represented in Fig. 948. It has the form of a freshwater Unio, and the name Amnigenia, of Hall, alludes to its suspected freshwater habitat. It is from the " Oneonta sandstone " of Chenango and Otsego counties, N.Y., and has been found also in the Catskill beds of Bedford County, Pa. The " Black shale " of Ohio and the states west and south, which repre- sents the Genesee with more or less of the Portage and Chemung beds, is remarkable for the great rarity of fossils. In Ohio the lower beds have afforded the Portage species : Chonetes scitulus, Ooniatites complanatus, Coleo- lus acicula, Styliolina fissurella ; and the upper and middle portion, the Chemung species: Leiorhynchus mesacostale, Spirifer disjunctus, S. altus; also species of Lingula and Orbiculoidea. Southern Indiana has afforded Lingula spatulata, Discina (Schizobolus) truncata, Chonetes lepidus, Leiorhyn- chus quadricostatum (Genesee species), L. limitare (a Marcellus sp.), Styliolina fissurella. Fossil plants also are rare ; but wood of Gymnosperms, referred to Dadoxylon and Cordaites, is found in it. In most parts of the shale, Sporangites are in great abundance, S. Huronensis of Dawson, -^ to -3-^5- inch in diameter. Gastropods are few in both the Portage and Chemung beds. The prolific genera of the earlier Devonian, Platyceras and Platystoma, have a number PALEOZOIC TIME DEVONIAN. 613 of species. The genera having the most of the species are Loxonema, Cydo- nema, and Bellerophon. Conularice are not uncommon. 939-947. 939. 943. 944. BBACHIOPODS, Chemung. Figs. 939, 939 a, Khynchonella contracts ; 940, 940 a, Productella lacrymosa ; 941, Atrypa hystrix; 942 a, 6, Spiriferdisjunctus. LAMELLIBRANCHS. Fig. 943, Aviculopecten duplicates ; 944, Pterinea Chemungensis ; 945, Leptodesma lichas. GASTROPOD. Fig. 946, Bellerophon maera ; 947, Bactrites acicula. From Hall. 948. LAMELLIBBAKCH, Catskill. Amnigenia Catskillensis. Vanuxem. Cephalopods are few, except under the genera Goniatites and Orthoceras. The thin Styliolina limestone bed in the Genesee shale contains several 614 HISTORICAL GEOLOGY. species of Goniatites and Orthoceras, and a few other species. The Naples beds, in the Lower Portage, have afforded the first of American species of 949-953. 949. 953. 954. Fig. 949, Clymenia Neapolitans, of New York (x 4) ; 950, profile of same ; 951, transverse section near beginning of 5th whorl ; 952, same at end of 1st, 2d, 3d, and 4th whorls ; 953, form of the suture at 2$ revolutions. J. M. Clarke. Clymenia (Fig. 949), a genus related to Nautilus, but having the siphuncle dorsal (Fig. 951). Fig. 954 represents Goniatites intumescens (G. Patersoni Hall) of the same beds ; it occurs also in the Ithaca group. The so-called Catskill beds contain no remains of marine Mollusks of any kind, except occasionally such as are regarded as Chemung, and as indications that the beds are Chemung. 5. Crustaceans. Trilobites have not a re- corded species from the New York Portage ; and in the Chemung occur only Phacops nupera H., doubtfully, and Cyphasphis Ice-vis H., Phacops rana and Dalmanites (Cry- phceus) Boothi. But conditions were more favorable in Ohio, and a Chemung fauna, according to Herrick, has afforded the follow- ing species : Proetus minutus Hk., P. prcecursor, P. doris Winchell, P. auric- ulatus H., Phcethonides occidentalis Hk., P. spinosus Hk., and others. Phyllopod Crustaceans were of various forms and species in the Portage, Goniatites Patersoni Hall. PALEOZOIC TIME DEVONIAN. 615 and besides these, there are the first of true Shrimps, or Macrural Decapod 965-958. 958. 957. POBTAGE. Fig. 955, Mesothyra Ocean! ; 956, Dipterocaris penna Dsedali ; 957, D. Procne ; 958, Palseopatemon Newberryi. Fig. 955, Hall ; 956, 957, J. M. Clarke ; 958, Whitfield. Crustaceans, Palceopalcemon Newberryi of Whitfield (Fig. 958). Phyllopod genus Echinocaris of the same author there are a number of species ; and the related Me- sothyra Oceani of Hall (Fig. 955) had a length and breadth of more than 10 and 5 inches. Figs. 956 and 957 represent carapaces of two other Phyllo- pods. The specimen of Palceopalcemon was found in Ohio, in the lower part of the Ohio shale. 6. Limuloids. The lower beds of the Portage and Upper Chemung have afforded species of Euryp- terus. Also a few abdominal segments of great size, which have been made the basis of the species Stylo- nurus Wrightianus, supposed to have been two feet long. Of Catskill Eurypterids, one gigantic species, Sty- lonurus excelsior H., has been described from imper- fect specimens found in the Catskill beds of Delaware County, N.Y., and Wyoming County, Pa. The cara- Under the CHEMTJNG. Fig. 959, Protollm- ulus Eriensis, ventral side. H. S. Williams. 616 HISTORICAL GEOLOGY. pace is nearly 10 inches square, the toothed-edge of the mandible 1J inches long, and the whole length probably over 4 feet (Hall). In addition, a 960-962. 960 a. 960. PLACODERMS. Fig. 960, Bothriolepis Canadensis (x J), dorsal view; 960 o, id. ventral view ; from Whiteaves; m. v., middle ventral plate; a. m. v., anterior middle ventral; a. v., anterior ventral; p. v., posterior ven- tral; 961, terminal part of pectoral limb of a Bothriolepis (Cope); 962, plate of a Bothriolepis (Leidy). 963. 964. COOCOBTEID FISHES. Fig. 963 restored ventral plates of Holonema rugosum (x J), from H. 8. Williams; 964, restored ventral plates of Phlyctaenaspis Acadica of Whiteaves (x ), from Traquair. species, related apparently to Limulus (Fig. 959), has been found in the PALEOZOIC TIME DEVONIAN. 617 Chemung of Erie County, Pa. It is the Protolimulus Eriensis of H. S. Williams. 7. Vertebrates. Remains of Placoderms, of the brachiate type, or re- lated to Pterichthys, have been found in Ohio and in the Catskill sandstone of New York and Pennsylvania, and nearly perfect specimens (Figs. 960, 960 a) of one species, Bothriolepis Canadensis of Whiteaves, at Scaumenac Bay (in Baie de Chaleurs), New Brunswick. Fig. 960 is a view of the dorsal shield, and 960 a, the ventral, both reduced to a third of the natural size ; and 960 shows also the probable outline of the posterior extremity, which has been added to Whiteaves's figures from the form in Pterichthys. Fig. 961 represents, natural size, the finger-like termination of a fore limb of possibly the same species, described by Cope, which was found at Mansfield, 965. 965-969. 966. DIPNOAN FISHES. Fi?. 965, Dinichthys Hertzeri, front view of jaws (x ^); 966, ventral plates (x^,): 967. palate tooth of Dipterus Sherwoodi ; 968, id. of Ctenodus Nelsoni : all from Newberry. Fig. 969, Pliaueropleuron curtum (x|), from Whiteaves. Tioga County, Pa., with remains of Holonema. Fig. 962 represents a plate of Bothriolepis from the Catskill beds. No remains of the posterior scaly part of the body have been observed in connection with specimens of the American species of Bothriolepis, though occurring in Scotland with those of Pterichthys. 618 HISTORICAL GEOLOGY. The Coccosteus family was represented by species of large size. The ventral plates of two are represented on page 616. Fig. 963 is Holonema rugosum of Claypole; as determined by H. S. Williams, the central plate in the ventral shield (m. v.) has a length of 8^ inches. The specimen figured is from the Oneonta sandstone, near Oxford, N.Y. In the related species, Fig. 964, from Campbelltown, New Brunswick, the central plate is but one inch long. 970-974. 970. OANOIDS. Fig. 970, Glyptolepis Quebecensis (xf); 971, Eusthenopteron Foordi (x|); 972 , scale from a species of Holoptychius ; 973, tooth, id. ; 974, Chirolepis Canadensis. Figs. 970, 971, 974, Whiteaves ; 972, 973, Leidy. The Dipnoans, or "Lung-fishes," were represented by gigantic species called by Newberry Dinichihys and Titanichthys, from their size and formi- dable dental armature. The species of Dinichihys, to which Figs. 965, 966 PALEOZOIC TIME DEVONIAN. 619 pertain, were described from specimens found in the Cleveland shale of Ohio. Fig. 965 shows the form of the upper and lower jaws in natural position of Dinichthys Hertzeri. To represent the natural size, the figure should have a breadth of 45 inches. Fig. 966 is the ventral shield. It resembles that of Coccosteus, and also that of Bothriolepis. A still larger species is the Titaniclitliys Clarki of Newberry, in which the head was four feet or more broad, the lower jaw a yard long. This jaw was shaped posteriorly like an oar blade, and anteriorly was turned upward like a sled-runner. Dinichthys Oouldi of Newberry had enormous eyes surrounded by sclerotic plates. The Phaneropleuron of Whiteaves (Fig. 969) is a smaller Dipnoan from the Upper Devonian at Scaumenac Bay, New Brunswick. Figs. 967, 968 rep- resent the palate teeth of two Dipnoan s ; such teeth, and the brachiate pec- toral and ventral fins are special Dipnoan characteristics. 975-977. SELACHIANS. 975, Cladodus sinuatus (x J) ; 976, tooth of C. Clarki ; 977, C. Fyleri (xf ). Tigs. 975, 976, Ckypole ; 977, Newberry. Fig. 970 represents a Ganoid of Crossopterygian type as indicated in this figure by the thickened finger-like medial portion of the pectoral fin a structure better exemplified in Fig. 969. A scale of a related genus, Holoptychius, is represented, of natural size, in Fig. 972, and a tooth, referred to the same genus by Leidy, in Fig. 973. (See also page 625 for a figure of a nearly complete specimen of another species.) The genus Eusthenopteron of Whiteaves (Fig. 971) has special interest on account (as the name implies) of the supports with which the fins are provided, answering to the pectoral and pelvic arches of higher Vertebrates a, the pectoral, and 6, the pelvic (only two bones of which are preserved) ; and also the similar and even larger supports for the anal fin at c and for the posterior dorsal at d, with a 620 HISTORICAL GEOLOGY. like arrangement, but less perfectly, for the lower part of the caudal fin. They gave the posterior part of the body great strength for sculling. It is further to be observed that the open space along the center of the vertebral column indicates a persistent notochord (cartilaginous), the spinous processes being the only calcareous portions of the column. Fig. 974 represents a Canada species of Chirolepis, a genus of the family Palseoniscidse. Palceo- niscus Devonicus of Clarke is another Devonian Ganoid, from the Portage of New York. The species, Figs. 970, 971, 974, are from Scaumenac Bay. /Selachians, or Sharks, were represented not only by fin-spines and teeth, but also, in the Cleveland shale of Ohio, by impressions or remains of the nearly entire body. Two speci- 978. mens of the latter are shown, much reduced, in Figs. 975, 977. The largest yet found, Cladodus Kepleri, had a length of six feet. Newberry's figure of C. Fyleri, in his Paleozoic Fishes of North SELACHIAN. -Fig. 978, Acanthodes affinis; a, scales, America, gives it a length of natural size, whiteaves. 22 inches. It is referred to a new genus, Cladoselacha, by B. Dean. The tooth, Fig. 976, is of the species Cladodus Clarki of Claypole. Kemains of a species of another genus, Acanthodes, related to the Sharks, but having minute square or rhombic scales, has been found at Scaumenac Bay. A small specimen is represented in Hg. 978. Other species of the genus have been reported from New York and Pennsylvania. Characteristic Species. Genesee shales. Orbiculoidea Lodensis, Discina truncata, Lingula spatulata (also Portage), Chonetes lepidus (also Hamilton), Amboccelia umbonata (also Ham. & Mar.), Leiorhynchus quadricostatum, Strophalosia truncata (also Marcelltis), Lunulicardium- fragile (Marcellus to Portage), Cardiola (Glyptocardia") speciosa (Ham. to Chemung), Styliolina fissurella, Tentaculites gracilistriatus (also in the Marcellus), Orthoceras subu- latum (also Marcellus), Goniatites complanatus (also Upper Ham. and Portage), G. dis- coideus (Marc., Ham. also), G. intumescens ( = G. Patersoni} (also Portage and Chemung). Portage group. Amboccelia umbonata, Grammysia subarcuata, Lunulicardium fragile, L. acutirostrum, L. ornatum, Cardiola speciosa, Styliolina fissu rella, Bellerophon natator, Coleolus acicula, Tentaculites gracilistriatus, Orthoceras pacator, Goniatites complanatus, G. intumescens, G. bicostatus, G. sinuosus. Ithaca beds (noted for the number of Brachiopods) . Lingula spatulata, Atrypa reticularis, Spirifer mesacostalis and S. mesastrialis, Cryptonella eudora, Stropheodonta mucronata, Ehynchonella pugnus, R. eximia, Productella speciosa, Leiorhynchus mesa- costale, Orthis impressa, Chonetes setigerus, C. scitulus, Crania ; Lunulicardium fragile, Schizodus quadrangularis, Palceoneilo filosa, species of Leptodesrna and Aviculopecten, Grammysia subarcuata, Tentaculites spiculus, Orthoceras bebryx, 0. fulgidum. Spathio- caris Emersoni Clarke, of the Portage, is described and figured in Am. Jour. Sc., xxiii., 1882. The Palceopalcemon was first described by Whitfield, in Am. Jour. Sc., xix., 1880. The Naples beds, in the Portage, containing the Clymenia (Fig. 949), have afforded also, according to J. M. Clarke (1891, '92), Palceoniscus Dzvonicus Clarke, Acanthodes PALEOZOIC TIME DEVONIAN. 621 priscusCl, Conodonts, Echinocaris Whitjieldi CL, E.? Beecheri Cl., Spathiocaris Emersoni Cl., species of Entomis, Goniatites intumescens Beyrich, and many other species of the genus, Orthoceras pacator Hall, and other species of 0., species of Bactrites, Bactrites? acicula, Hyolithes, Tentaculites gracilistriatus, Styliolina fissurella Hall, species of Macrocheilus, Platystoma, Pleurotomaria, Loxonema, Bellerophon, Leptodesma, Leiopteria, Grammysia, Macrodon, Nucula, Ungulina, Lunulicardium, Cardiola (Cardiola retrostriata abundant), Pholadella, Lingula, Chonetes, Aulopora, Melocrinus Clarki Williams, also species of fossil wood. The Styliolina limestone, in the Genesee shale below, contains the first representatives of the Naples, or G. intumescens, fauna ; in it, Dawson has identified Dadoxylon (Cordaites") Clarki, Cladoxylon mirabile Unger. The fauna and flora are related to that associated with Goniatites intumescens in Europe. (J. M. Clarke.) Chemung beds of New York and Pennsylvania. Dictyophyton tuberosum ; Orthis Tioga, 0. impressa, Stropheodonta Cayuta, Productella lachrymosa, P. hirsuta, Rhynchonella contracta, Leiorhynchus sinuatum, L. mesacostale, Spirifer disjunctus, Ambocwlia umbonata var. gregaria, Athyris Angelica; Aviculopecten duplicatus, Ptennea Chemungensis, Ptychopteria Sao, P. falcata, Leptodesma spinigerum, Goniophora Che- mungensis, Schizodus Chemungensis, Grammysia subarcuata, G. communis, Sphenotus contractus, Prorhynchus nasutum ; Tropidocaris bicarinata, Echinocaris socialis. For descriptions of Chemung fossils see Pal. N. Y., vols. iv., v., vii., viii. (C. E. Beecher.) Lamellibranchs of the Middle and Upper Devonian. The total number of species of Lamellibranchs described and figured by Hall in vol. v. of the Palaeontology of New York is 458 ; and of these 195 occur in the Hamilton beds, and 263 in the Chemung. The principal genera to which they are referred, and the number of species in each, are as follows H. signifying Hamilton, and C., Chemung : Actinopteria (H. 7, C. 10), Aviculopecten (H. 13, C. 16), Conocardium (H. 4, C. 2), Cypricardinia (H. 2, C. 1), Edmondia (H. 0, C. 7), Glossites (H. 1, C. 7), Goniophora (H. 7, C. 4), Grammysia (H. 15,-C. 9), Leda (H. 4, C. 0), Leiopteria (H. 12, C. 3), Lep- todesma (H. 2, C. 55), Lunulicardium (H. 7, C. 6), Microdon (H. 4, C. 2), Modiomorpha (H. 10, C. 7), Mytilarca (H. 2, C. 8), Nucula (H. 9, C. 5), Nuculites (H. 5, C. 0), Ortho- nota (H. 4, C. 1), Palceanatina (H. 0, C. 4), Pal&oneilo (H. 10, C. 10), Panenka (H. 12, C. 3), Paracyclas (H. 4, C. 5), Prorhynchus (H. 0, C. 3), Ptennea (H. 1, C. 10), Ptychopteria (H. 0, C. 22), Schizodus (H. 3, C. 8), Sphenotus (H. 5, C. 5). E. D. Cope has announced (1892), from the bed containing Fish remains, of Chemung age, in Mansfield, Tioga County, Pa., besides Holoptychius Americanus, the species Bothrio- lepis nitida Leidy, Holonema rugosum Clayp., Ganorhynchus oblongum Cope, Holoptychius giganteus Ag. ; in Leroy, Bradford County, Pa., the bed probably Chemung, H. rugosus, H. horridus Cope, H. filosus Cope ; at a neighboring locality, Bothriolepis minor Newb., Coccosteus macromus Cope, and fragments of Osteolepisor Megalichthys. Phaneropleuron curtum of Whiteaves (Fig. 969) has been made by Traquair into a new genus, named Scaumenacia, on the basis of a slight difference, in the dorsal or dorso-caudal fin, between it and the original Phaneropleuron of Huxley. Plates of the large pterichthyoid fish, Holonema rugosum, have been found in the red sandstones of the Oneonta group, near Oxford, N.Y. (See Proc. A. A. A. S., vol. 39, 1890, page 337. Also, Am. Geol, vol. vi., page 226.) The minute teeth, long of doubtful ownership, called Conodonts, now regarded as the teeth of Annelids, occur of several species in the Genesee shales of Erie County, N.Y., at North Evans, including the following described by Hinde (Q. J. G. Soc., 1877): Prioniodus angulatus, P. acicularis, P. armatus, P. spicatus, P. erraticus, Polygnathus dubius, P. nasutus, P. princeps, P. palmatus, P. punctatus. A plate is devoted to figures of Conodonts (PI. 57), in Ohio Pal., ii., 1875. Additional Devonian plants. The following are some of the species of St. John, New Brunswick ; those that occur also at Gasp6 are marked with an asterisk, and those also in New York or farther West, with a dagger. 622 HISTORICAL GEOLOGY. Psilophyton pri nceps Dn.*t(Fig. 854, page 583), Lepidodendron Gaspianum Dn.,(Fig. 855), Sigillaria palpebra Dn., Stigmaria perlata Dn., Cordaites Robbii t (Fig. 896), Archce- opteris Jacksoni (Figs. 898, 899), Neuropteris polymorpha Dn. (Fig. 897), N. Dawsoni Hartt (leaflet over six inches long), jSphenopteris Hitchcockiana Dn., S. Hceninghausi Brngt., S. Hartti Dn., Callipteris pilosa Dn., Hymenophyllites Gersdorfi Gopp., H. obtusilobus Gopp., Alethopteris discrepans Dn., Pecopteris preciosa Hartt, species of Trichomanites, Calamites radiatus Gopp. (Fig. 900), C. cannceformis Schlotheim, Astero- phyllites acicularis Dn., A. latifolius Dn. (Fig. 901), Sphenophyllum antiquum Dn. ; Dadoxylon Ouangondianum Dn., besides fruits of Gymnosperms, of the genera Cardio- carpus and Trigonocarpus. A Gymnosperm fossil wood, from Schoharie County, N.Y., has been named Or- moxylon Erianum by Dawson. At Perry, Me., occur Lepidodendron Gaspianum Dn., Leptophlceum rhombicum Dn., Archceopteris Jacksoni Dn., A. Halliana, A. Rogersi Dn., A. (Cyclopteris) Browni Dn., Caulopteris Lockwoodi Dn., Anarthrocanna Perry ana Dn., Stigmaria pusilla Dn., and others, there being very few of the St. John species. Some species are the same that occur in Subcarboniferous beds. See, for descriptions of plants, in addition to Dawson's publications, also C. F. Hartt in Bailey's New Brunswick Geol. Bep., 1865 ; Lesquereux, Report on Goal Flora of Pennsylvania, and another on Indiana; Newberry's Ohio Reports, and other publications, etc. FOREIGN. The Devonian beds in the British Isles comprise the Old Eed sandstone of Scotland; the same in southeastern Wales and the adjoining region of Herefordshire in England, and of some parts of Ireland ; and areas of slates and limestone in Devon and Cornwall, or southeastern England. The fossil- iferous Devon areas suggested the name for the beds. The more northern of the Scottish areas (a) stretches in a south- southwest direction, from the Shetland and Orkney Islands, along the west coast of Scotland into Loch Ness ; it has for part of its western boundary the northern Highland Archaean region of Scotland along which must have run a western shore-line in the Devonian sea. (b) Nearly parallel with this northern area, another crosses central Scotland from Stoneham to the Firth of Clyde ; and farther south, beyond a Carboniferous belt, is still another interrupted line ; and this central trough of chiefly Devonian .and Carboniferous rocks, about 50 miles wide, is in the line of the area of Car- boniferous beds (mostly Subcarboniferous), and outcrops of Devonian, which occur over western Ireland, (c) A third area is . that of eastern Wales and the country adjoining; it has the Siluro-Cambrian region of Wales as its western border ; and its continuation southwestward embraces the Carbonif- erous area of South Wales ; thence, the combined Devonian and Carboniferous area extends over Devon and Cornwall. The northeastward and eastward continuation of this third area to the North Sea is under the cover of Triassic and later rocks, except where Carboniferous beds outcrop. Borings have been supposed to prove the presence of Devonian shales and sandstone to the eastward, under London, at a depth of about 1000 feet, Etheridge identifying the fossils Spirifer disjunctus, Rhynclionella cuboides with species of Orthis, Chonetes, and Edmondia. PALEOZOIC TIME DEVONIAN. 623 979. The Old Red sandstone is the rock of all the areas excepting that of Devon and Cornwall. It consists of red, purplish, and brown sandstones, coarse and fine, passing to a conglomerate and also to bituminous flags. It shows by its coarse and varying features, by the absence of fossiliferous beds bearing shells, corals, and other invertebrate remains, and by the presence here and there of relics of Fishes and Eurypterids, that its origin was much like that of the Catskill Red sandstone of eastern America a roughly made sea-border formation, in waters that suffered in purity from the contri- butions of streams from the bordering hills. The American Devonian has abundant life beyond the Catskill sandstone area ; and in the British seas the beds of Devon are as prolific as the Chemung, Hamilton, and Corniferous of eastern America. The Old Red sandstone of Scotland (called Old Red in contrast with the New Red or Triassic) is reported to have the extraordinary thickness of 10,000 to 16,000 feet. It is divided into an Upper and Lower division, by a plane of unconf ormability above the level of the Caithness flags (A. Geikie). Besides sand- stones the central basin of Scotland includes a great thickness (6000 feet) of igne- ous rocks f elsy te and f el- syte porphyry, doleryte and other kinds ; now forming, as Geikie states, chains of hills, as in the Pentland, Orchir and Sidlaw ranges. They occur interstratified with the ordi- nary beds, several thousand feet above the base of the Devonian, and indicate a long period of ejections. The ba- sins of the Cheviot Hills and of Lome also had their vol- canic ejections. The Old Red sandstone is remarkable for its Eurypterids. A Pterygotus is represented in Fig. 979, P. Anglicus, which has a length of six feet more than three times that of any Crustacean now living. Other common genera are Eurypterus and Stylonurus. An Ostracoid, Estheria, is abundant in some places. A gigantic Isopod Crustacean, the Prcearcturus, has been described by Woodward (1870) from the Old Red sandstone of Herefordshire. EUBYPTERID. Fig. 979, Pterygotus Anglicus ; a, eye; /, appendages ; 1 to 13, numbering of segments. 624 HISTOKICAL GEOLOGY. Modern Isopods are seldom over two inches long. The basal joint of a leg of the Praearcturus was three inches long, and three quarters of an inch 980-983. 980. PLA.CODERMS. Fig. 980, Cephalaspis Lyelli (x|); 980 a, same, with pectoral fins in place; 980 6, c, scales; 981, Coccosteus decipiens, side view; 981 a, dorsal plates; 982, Pterichthys Milleri (x|) ; 983, Pterichthys cornutus. Figs. 980, 981, Agassiz ; 981 a, 983, Traquair ; 982, Pander. PALEOZOIC TIME DEVONIAN. 625 through. Two species of Myriapods have been described from the lower Old Red sandstone of Forfarshire, Scotland, Kampecaris Forfarensis Page, and Archidesmus MacNicoli Peach. The Fishes of the Old Red sandstone have come mostly from bituminous flags in northern Scotland and North Wales, and include species of the Placoderm genera Cephalaspis (Fig. 980), Pteraspis, Cyathaspis, Auchenaspis, Holaspis; Aster olepis, Pterichtliys (Figs. 982, 983), Bothriolepis, Coccosteus (Fig. 981); also the Dipnoan genera, Dipterus, Phaneropleuron ; and the true Ganoids, Holoptychius, Glyptolepis, Dendrodus, Cheiracanthus. The Cephal- aspids are absent from the Upper Devonian of Scotland. 984-985. 984 984 a. 985 a GANOID. Fig. 984, Holoptychius (x) ; 984 a, a scale. DIPNOAN. 985, Dipterus macrolepidotus (x J) ; 985 a, a scale. The Devon beds have an estimated thickness of 10,000' to 12,000'. They afford a large variety of Corals, Brachiopods, and other species, a number of them related to those of the American Devonian. 1 The Lower, Middle, and Upper divisions are: (l)the LOWER or LYNTON group of sandy slates and grits, affording Actinocrinus tenuistriatus, Favosites cervicornis,Orthisarcuata, 0. granulosa, Spirifer canaliferus, S.hystericus, S.lcevicostatus, Streptorhynchus umbraculum, Chonetes Hardrensis ; (2) the MIDDLE or ILFRACOMBE group of slate and grits, with beds of limestone, containing several species of Crinoids ; many Corals, including Heliophyllum Halli, Cynthophyllum c&spitosum, species of Favosites, Acervidaria, etc.; Stromatopora of several species ; Atrypa reticularis, A. Icevis, A.aspera, Ehynchonella cuboides, Merista plebeia, Orthis striatida, Spirifer curvatus, S. disjunctus, String ocephalus Burtini, Streptorhynchus crenistria, Strophomena rhomboidalis, Platy- ceras vetustum, species of Euomphalus, Loxonema, Murchisonia ; Goniatites, Orthoceras, Cyrtoceras ; Tentaculites scalans; Phacops latifrons, P. granulata, and also species of Bronteus, Harpes and Ceraurus (3) UPPER, including Pickwell Down and Pilton beds, 1 In the following lists of foreign species, the new generic names of Brachiopods, recently introduced by Hall and Clarke in their revision of the subject, are not inserted, as they are not yet in use in anv foreign work on geology or paleontology. DANA'S MANUAL 40 626 HISTORICAL GEOLOGY. containing many Crinoids and Brachiopods : Pentremites ovalis, Athyris concentrtca, Spirifer decussatus, S. Urii, Orthis plicata, O. parallela, 0. interlineata, Productus prcelongus, Streptorhynchus crenistria ; with several species of Clymenia, Goniatites, Orthoceras also Phacops latifrons, etc. Among the Devonian plants of Ireland, in beds that contain also remains of Coccos- teus and Glyptolepis,. there are Cyclopteris Hibernica Forbes, Sphenopteris Hookeri Baily, S- Humphriesiana, Catamites radiatus Br., Lepidodendron Veltheimanum Sternb., Knor- ria acicularis Gopp., Cyclostigma minutum Haughton, C. Kiltorkense Haughton, and other species. The whole number known of species of Fishes from the Lower Devonian of Great Britain, as stated by Etheridge in 1885, is 88, 4 species of Onchus being ex- cluded ; in the Middle Devonian, 2 ; in the Upper, 28. The only genera common to the Lower and Upper are Pterichthys, Asterolepis, Holoptychius and Platygnathus. Of the 577 species in the fauna, 50 pass up into the Carboniferous. In the Ardennes, on the borders of France and Belgium, there is the west border of a broad Devonian area which crosses the Rhine north of Mayence with bold features along the river, and extends to Nassau and Westphalia. The Lower, Middle, and Upper divisions are named(l) the Rhenan, (2) the Eifelian, and (3) the Famennian. In the region of the Ardennes the Lower consists, according to Gosselet, of (1) the Gedinnian, about 2500' thick, containing Homalonotus, Tentaculites, Spirifer Dumonti ; (2) the Taunusian, about 1800' thick, with Pleurodictyon, Lcptcena Murchisoni, L. laticosta ; (3) the Coblenzian, about 8000' thick, with Strophomena depressa, Grammysia Hamiltonensis ( = bisulcata) ; and at top, Spirifer cultrijugatus, Calceola sandalina (the latter, perhaps, Eifelian). The Middle or Eifelian^ over 3000' thick, includes the Calceola slates, and above these the Givet lime- 986-987. 987. CEPHALOPODS. Fig. 986, Clymenia Sedgwicki ; 986 o, dorsal view of septa ; 987, Goniatites retrorsus. Fig. 836, D'Orbigny ; 98T, Vogt. stone (Givetiari) or Stringocephalus beds ; the former containing Phacops, Sronteus, Orthis striatula, Productus subaculeatus, Pentamerus galeatus ; the latter, Stringocephalus JSurtini, Heliolites porosus, etc. The Upper or Famennian, over 2500', consisting of the Frasnian shales and limestone below, and the Famennian shales and Sandstones of Condros above, with Atrypa reticularis, Orthis striatula, Spirifer Verneuili (S. disjunctus*) , Clymenia, Archceopteris Hibernica, Sphenopteris Jlaccida. The Devonian outcrops also to the northwest in the Boulonnais, in Brittany -and the Vosges, and to the eastward, in the Harz and Thuringia. PALEOZOIC TIME DEVONIAN. 627 In the Eifel, the three divisions, the Bhenan, Eifelian and Famennian are well developed. The Ehenan contains Dalmanites, Phacops latifrons, Spirifer cultrijugatus, etc. The Eifelian consists below of the Calceola beds, with C. sandalina and Spirifer cultrijugatus, and above, of the Stringocephalus beds. The Famennian, or Upper Devonian, consists of (1, or below) the Cuboides shale with dolomytic beds, containing Ehynchonella cuboides, Spirifer glaber, S. Verneuili, S. Urii, Atrypa reticularis, Athyris concentrica, Productus subaculeatus, Camarophoria formosa; (2) Goniatite bed, with Goniatites retrorsus (Fig. 987) , G. primordialis, Orthoceras sub- flexuosum, Bactrites gracilis, Pleurotomaria turbinea, Cardiola retrostriala, Cypridina serrato-striata ; (3) the Cypridina shale, with C. serrato-striata (Fig. 989) and Posido- nomya venusta. Similar subdivisions occur in Westphalia and Nassau, the Fichtelgebirge, and other areas of Germany. In the Thuringian Forest and the Fichtelgebirge, the Upper Devonian con- tains in the Clymenia and Orthoceratite limestones, Clymenia Icevigata, C. undulata, 988-989. 989 a. CBTTSTACEANS. Fig. 988, Arges annatus of the Eifel ; 989, slate, from Weilburg, containing Cypridina serrato- striata, natural size ; 989 a, same enlarged. Vogt. Goniatites retrorsus, G. intumescens, Orthoceras interruptnm, Gomphoceras, Cyrtoceras, Athyris concentrica, Ehynchonella cuboides, Bronteus grandis, and other species, besides remains of Calamites, Lepidodendron, Stigmaria, Aporoxylon. In Russia (the Continental Interior of Europe) the Devonian beds cover a large area, and are nearly horizontal. The western areas include only Middle and Upper Devonian. Below are limestone and red marls; and above, limestone and shales with some sand- stones, having partly the character of the Old Red sandstone of Scotland, and like that containing, says Murchison, remains, of Fishes as almost the only fossils. Pander has described species of Coccosteus, Osteolepis, Dipterus, and Diplopterus from the Middle, and Holoptychiits nobilissimus, Pterichthys major, and Asterolepis from the Upper. The Lower, Middle, and Upper Devonian occur in the Urals, through nearly the whole length of the range. In South America, Devonian beds occur over the Highlands of eastern Bolivia, Lower and Middle Devonian (D'Orbigny, M. D. Forbes, Steinmann); in the region of Lake Titicaca, Lower Devonian (Agassiz and Garman) ; in Brazil, in the province of Para, north and south of the Amazon, 200 to 400 miles from the coast, Lower, Middle, and Upper Devonian (O. A. Derby, and others) ; in the Falkland Islands (Darwin). In the vicin- ity of the Amazon, on its north rise, Hamilton beds include species of the genera Vitulina, Tropidoleptus, JRetzia, and others, described by Rathbun, and one variety of Discina Lodensis Hall. Ulrich reports, from eastern Bolivia, species of the genera Leptoccelia, Vitulina, and Tropidoleptus, besides others, and states that the first of these three genera occurs also in the Devonian of the Falkland Islands and of South Africa, and that the second is also South African. (For remarks on the distribution of these and other genera, see 628 HISTOKICAL GEOLOGY. Address of H. S. Williams, Am. Assoc., 1892.) The Ida shales of Bolivia are Corniferoub, and the Huamampampa sandstone is Hamilton. In southwestern China Richthofen obtained from the Devonian beds the wide-range fossils Pentamerus galeatus, Atrypa reticularis var. desquamata, Merista plebeia, Spirifer Verneuili ( = disjunctus), Orthis striatula, Productus subaculeatus, titrophalosia pro- ductoides, Ehynchonella cuboides, E. pugnus, Aulopora tubiformis (China, iv., 75). Australian Devonian beds of the Itydal District, and to the north and south of it, have afforded the species Cyathophyllum Damnoniense, Favosites reticulatus, F. fibrosus, Heliolites porosus, Chonetes Hardrensis, Orthis striatula, Ehynchonella pleurodon, R. pugnus, E. cuboides, Atrypa reticularis, Spirifer Verneuili, and also the plant Lepido- dendron (W. B.Clarke, On. Sedim. Form. N.S.W., 4th edit., 1882). The Devonian occurs also in Queensland, and near Bathurst in Tasmania. GEOLOGICAL AND GEOGRAPHICAL PROGRESS DURING THE DEVONIAN. AMERICAN. In the Devonian era, as in the Upper Silurian, the great rock formations that are open to investigation were the work of the Interior Continental waters. Progress was still, in the main, endogenous, or within the Interior Sea. No Paleozoic rocks, later than the Lower Silurian, have yet been re- ported from the Atlantic border, along the coast region of New Jersey and the states southward. The confined condition of the Eastern Interior Sea, or Bay, had, with the progress of the era, an increasingly profound influence on the nature of the successive formations. The bay had its northwest passage over Michigan open, but not the northeast passage to Canada. The Devonian, as has been shown, began, like the Silurian, with beach and sea-border deposition, sparingly fossiliferous, marking off the coast-line on the north and northeast, and an off-shore bay-like formation the Schoharie bearing evidence of abundant life. But these rocks had acquired little thickness before the commencement of the Corniferous limestone formation, or rock coral-reef, when clearer waters, with growing Corals, Crinoids, Trilobites, and other species of the purer seas, were in great profusion, and spread from near the Hudson to Missouri and Iowa. The waters reached north to Mackinac, the head of a great Michigan bay of the era, but appear not to have covered northern Illinois or Wisconsin. Moreover, the Canada and New England seas also had their coral reefs. It is remarkable that this coral-reef rock is not recognized over Pennsyl- vania and to the southwest. The Eastern Interior Sea had open connection with the Central Interior by the northwest. As to the southern entrance, nothing is known. At the close of the Early Devonian the evidences of clear seas the Corals and Crinoids, with most of the attendant life disappear, migrating no one knows whither. Depositions of silt, mud, and sand prevail to the east- ward with various alternations and but thin intercalations of limestone ; and so it was also over the Central Interior, except sparingly in the Hamilton PALEOZOIC TIME DEVONIAN. 629 period. With the variations in the fineness, or other characteristics of the beds, as H. S. Williams has illustrated, the species vary. The fine shales of the Marcellus and Genesee shales have few and small species, owing to some unfavorable conditions ; and, in part, the species are repeated in each later return of the beds to fine shales. With the coarser sand-beds of the Hamilton and Chemung, life abounds; but Brachiopods and Lamellibranchs predominate, especially in the latter, where Trilobites fail completely. With beds of intermediate character, as those of the Portage, life is much less abundant than in the Chemung except at one time of change to beds allied to those of the Hamilton and Chemung (the Ithaca beds), when the life takes a character resembling that of the latter period. A thin lime- stone stratum in some cases indicates by the species an approximation again to the clearer waters of the Corniferous. There are thus alternations in living species correlatively with alternations in kinds of deposits. The species evidently migrated in the direction in which the conditions were favorable to them. The faunas of each stratum are not strictly faunas of epochs or periods of time, but local topographical faunas. After the Cor- niferous period, Corals, Crinoids, and Trilobites still flourished somewhere, as before ; but they are absent from the Central Interior until the Carbo- niferous age opens. The condition producing the Genesee shale in New York appears to have spread westward over Ohio, and to have invaded the Central Interior through Michigan, Indiana, the southern half of Illinois, and southward to Tennessee; and to have continued to prevail over this great region through the remainder of the Devonian era with but little change. The area was mud-making, with more evidence of fresh-water or brackish-water life than of marine conditions, and it probably had its extensive shallow lagoons and bayous in which lived the great Ganoids and Eurypterids. During the Later Devonian, in the Eastern Interior Sea, the Catskill sandstone to the northeast a shore and off-shore formation of the Interior Continental Sea reached a thickness of 3000 to 7545 feet (I. C. White), because it lay within the range of the Appa- lachian geosyncline. If the condition of the Atlantic border, its sounds and bays, with their varying depths and fortunes, and of off-shore deeper waters and depositions and fresh-water inlets, be taken as a type of the conditions and depositions that existed in several successions within the Eastern Interior Sea, no difficulty will be found in finding a reason for all the variations in wave action, in tidal and current action, in depth, in purity of waters ranging off to over-fresh or over-salt conditions, which may be needed to explain the geological and biological facts of the Middle and Later Devonian. The effects of tidal currents appear to be marked in the Chemung beds of western New York and Pennsylvania, and eastern Ohio. The strata of coarse conglomerates occurring among the sand-beds appear to be due to their action. The tidal waters, which, in their rounds, converged from the south and west toward the head of the Eastern Interior Bay, with increasing height 630 HISTORICAL GEOLOGY. as they advanced, may have made their ebb or their flow over this more western part of the bay-like channel ; and, by their rapid movement, have produced the assorting of the gravel and the accumulations of large stones or pebbles; and they may also, by some variation in their route, as time passed, have made pebble deposits locally at different levels. Such rapid tidal flows, causing the stones in shallow waters to slip over one another with each return of the current, would tend to make them flat, as in the Panama conglomerate, and not round as in ordinary round-pebble con- glomerates, the latter being work of plunging waves along a beach and of strong currents. BIOLOGICAL PROGRESS. The progress of the systems of life through the Devonian era was con- tinued into and through the following era without any abrupt transition, and the review of the subject is given for both eras after the account of the Carbonic era. UPTURNING OR MOUNTAIN-MAKING AT THE CLOSE OF THE DEVONIAN. Through nearly all of North America, where Devonian and Carboniferous rocks occur together, the two formations pass into one another continuously, as if one in series. But in eastern Canada at Gaspe, in Maine, and in Nova Scotia, and at Perry in southern New Brunswick, as reported by Dawson and Logan, there was an upturning of the Devonian and inferior beds, so that the overlying Carboniferous rests upon them unconformably. Dawson makes the unconformability general for the Acadian Provinces. The upturning and crystallization of the Devonian and Upper Silurian beds of the Connecticut valley, as well as of those of Lake Memphremagog and the St. Lawrence valley, may have been a part of the events of this epoch. But it is equally possible and probable that the upturning took place at the close of Paleozoic time. In Great Britain, Kussia, and Bohemia, some evidences of upturning between the Devonian and Carboniferous have been observed, and not in central and southern France. But all these cases are small exceptions to the general fact that the Lower Carboniferous and the underlying rocks are conformable almost the whole world over. The epoch of transition was not an epoch of general disturbance. There were extensive oscillations of level; but for the most part they involved no violent upturnings. The following era opens with a period of marine formations ; and the beds accu- mulated, in most regions where they occur, are a direct continuation of the deposits of the Devonian. PALEOZOIC TIME CARBONIC. CARBONIC ERA. SYNONYMY. Carboniferous and Permian periods, Lyell (Elements of Geol., 1839), and other British geologists, German geologists, and D'Orbigny, 1851, in France. Carbo- niferous age (Permian included), Dana, Man. Geol., 1st edit., 1863, 2d edit., 1874, 3d edit., 1880; Le Conte, Elements of Geol., 1877, and later; A. Winchell, Geol. Studies, 1886. Permo-Carboniferous, Dawson, Suppl. Acad. Geol., 1878. Carboniferous, Permo-Carbo- niferous, W. M. Fontaine and I. C. White, on Permian Plants of W. Va. and Penn., 1880. Permo-Carbonifere, Lapparent, Tr. de GeoL, 1883. Permo-Carbonic, Portuguese Commit- tee Internal. Congr. Geol., 1886. Carbonic (Permic or Permian included), E. Renevier, Tableau des Terrains Sedimentaires, 1874, Int. Congr. Geol., 1886. This first great coal-making era in the world's history commenced, both in Europe and America, with an extensive submergence of the land and a consequent formation of marine terranes of great thickness over parts of the continental areas. It passed its culmination during a long period of gen- tle oscillations in the surface, causing successive, more or less wide, emer- gencies and submergencies, the former favoring the growth of boundless forests and jungles, the latter burying the vegetable debris arid other terres- trial accumulations beneath marine or fresh-water deposits. It declined through a period in which the Carboniferous marshes gradually disappeared, as the sea regained its place over the land ; but again to retreat, as Paleozoic time ended, and the making of the Appalachian Mountains the next great event in North American history was commenced. The occurrence in Europe of alternating conditions like those of eastern North America is part of the evidence that the coal formations of the two continents were essentially cotemporaneous in origin. Facts from the fossils sustain this conclusion. They lead to the following subdivisions of the era: SUBDIVISIONS OF THE CARBONIC ERA. 3. PERMIAN PERIOD. Part of New Bed Sandstone or Poikilitic group of J. Phillips (the rest Trias). Lower New Ked Sandstone or Magnesian limestone group, Lyell, El. GeoL, 2d edit, 1841. PERMIAN, Murchison, Leonh. u. Bronn'sJahrb., 1841, Phil. Mag., xix. 417 ; Murchison, de Verneuil, and Keyserling, Geol. Russ., 1845 ; Lyell, El. Geol, 3d edit., 1851. Permisches System, Geinitz, 1848, 1858. Part of Mercian (the rest Triassic and Jurassic), T. McK. Hughes, Proc. Cambr. Phil. Soc., iii. 24. Dyas, J. Marcou, Dyas et Trias, Gen&ve, 1859, H. B. Geinitz, 1861, 1862 (Murchison's Permian having been made by him to include a small part of the Trias in Germany, though not of that in England). 2. CARBONIFEROUS PERIOD. The Coal-measures, with the underlying Mill- stone Grit. Carboniferous period of Lyell, Murchison, and other English geologists (the Mountain limestone commonly included). 632 HISTORICAL GEOLOGY. Carboniferien, Calcaire Carbonifere et Terrain Houiller, E. de Beaumont, D'Orbigny. Carboniferous Period, Dana, Man. GeoL, 1st. edit., 1863 and later. Pennsylvania!!, H. S. Williams, U. S. GeoL Surv., Bull. 80, 1891. 1. SUBCARBONIFEROUS PERIOD. Mountain, or Carboniferous, limestone, the lower division of the Carboniferous system, Murchison, Lyell, etc. Lower Carboniferous. Lower part of the Systeme Carboniferien, Calcaire Carbonifere, D'Orbigny, Lapparent. Bergkalk, Untercarbon. Subcarboniferous, D. D. Owen, Rep. Geol. Wisconsin, Iowa, and Minnesota, 1852 ; Dana, Man. GeoL, 1863 and in subsequent editions. Subcarbon, Steinmann and Doderlein, Elem. d. Pal., 1888. Mississippian, H. S. Williams, U. S. GeoL Surv., Bull. 80, Correlation of the Devonian and Carboniferous, 1891. Eocarboniferous, H. S. Williams, Journ. GeoL, Chicago, 1894. The comprising of the Permian period and the Carboniferous in a common era is questioned by some geologists. In North America the Permian beds are a direct continuation of the Carboniferous, and from the general absence of vertebrate and invertebrate fossils they are scarcely separable in most regions except through a careful study of the fossil plants. Such a study, made for Pennsylvania and Virginia in part by Lesquereux, but with completeness by Fontaine and I. C. White, has afforded satisfactory proof, as they state, that the Permian is fully represented in eastern America, and that the period is here only a continuation of, or a closing addition to, the Carboniferous period. There is the same evidence from the plants and also from the nearly universal conformity in the stratification of the two formations as to the close relations of the two periods in Europe, and this is sustained paleontologically, as these authors remark, " by the investiga- tions of Weiss, Grand' Eury, and others." The other continents were not so well supplied with coal-making areas as North America and Europe. South America has the rocks over part of its great interior, with little of the coal, and is in this respect like the western half of North America. Asia has much coal of the Carboniferous period in northern China. But in India, or southern Asia, the chief coal era began in the Permian and con- tinued into the Triassic ; and the same was true for southwestern Africa, and the southern continent, Australia. The fact that one of the world's hemi- spheres was not concurrent in its geological movements with the other, mentioned on page 406, is here exemplified. It has afforded some strength to the argument that the Permian period should not be united to the Carboniferous. But the distinctions that exist can be recognized and ap- preciated for lands about the Indian Ocean, without interfering with the chronological subdivisions which best accord with the facts in the others where these subdivisions were first laid down. PALEOZOIC TIME CARBONIC. 633 NORTH AMERICA. TOPOGRAPHY. The topography of the continent at the commencement of this era is approximately represented on the accompanying map, Fig. 990, on which the dotted lines over the surface, marking river courses, outlines of lakes, etc., are to be taken only as indicating positions. The chief change since the commencement of the Upper Silurian (page 536) is in the eastern portion or that of the Eastern Interior or Great Northeast Bay, which, at the opening of the coal era, was a complete bay in outline, reaching northeastward to the 990. Map of part of North America at the commencement of the Carbonic era. boundary of northeast Pennsylvania. It was in fact a double-headed bay, a branch passing northwestward from the Pennsylvania portion or bay (P), over Michigan, and making thereby a Michigan Bay ( M) . The Cincinnati Island (C) became part of the mainland, while the Tennessee was submerged. In addition, the Connecticut valley trough and the St. Lawrence valley trough were probably above the reach of salt water, or, at least, were not subsiding troughs, for no Carboniferous rocks occur within them; they were probably the courses of fresh-water streams. But the Gaspe- Worcester trough must have been an open channel, southward to Worcester at least, and the Acadian trough, from western Newfoundland to Narragansett Bay, was a still larger 634 HISTORICAL GEOLOGY. channel, in coal-making times, as is proved by the coal-beds in Newfound- land, Nova Scotia, and New Brunswick on the north, and in Ehode Island and a part of eastern Massachusetts on the south. The Western Interior, Rocky Mountain, and Pacific Border regions of the continent were largely covered by the Mediterranean Continental Sea, so that the western part of the map for the Upper Silurian era, on page 536, answers sufficiently well for this portion of the continent in the Carbonic era. SUBDIVISIONS. PENNSYLVANIA. ( The Upper Barren 3. Permian Period, -j , _ ( Measures. 4. Upper Productive Measures. 3. Lower Barren Meas- ures. 2. Lower Productive Measures. 1. Pottsville Conglom- . erate, or Millstone Grit. MISSISSIPPI BASIN. Permian beds. 2. Carboniferous Period. 1. Subcarboniferous Period. 2. Mauch Chunk group of Lesley. Umbral of Kogers. 1. Pocono group of Lesley. Vespertine of ^ Kogers. 2. Coal- measures. 1. Millstone Grit. 4. Chester, or Kaskas- kia group. 3. St. Louis group. c Warsaw. 2 ' Sa S e } Keokuk. grOUp ' (Burlington. 1. Kinderhook group. The Subcarboniferous rocks of the Mississippi basin are mainly great limestone formations. The term Subcarboniferous was first applied to them by D. D. Owen in his Quarto Keport, of 1852, on the Geology of Wisconsin, Iowa, and Minnesota. In this report (page 90) he divides the Carboniferous rocks of Iowa into "(1) the great calcareous formation at the base, (2) the coal-bearing strata in the middle, and (3) heavy beds of sandstone at the top," and gives (on page 92) a section of the " Subcarboniferous limestones." On the following page he presents a " table exhibiting the analogy between the Carboniferous limestones of Yorkshire, England, and those of Iowa," thus applying the term, in effect, to the corresponding rocks of Great Britain and Europe. The preposition sub is here used in the same sense as in substructure; and the great limestone formations of the Mississippi basin make a grand substructure for the coal-measures or the beds of the Carboniferous period. The term Mountain limestone, used for the British rocks, and for awhile employed in the United States, is not applicable to limestones of the plains. PALEOZOIC TIME CARBONIC. 635 GENERAL DISTRIBUTION OF THE ROCKS OF THE ERA. The geological map on page 412, though small, is sufficiently detailed to give a general idea of the distribution of the Carboniferous and Subcar- boniferous areas of the eastern part of the continent. The former are distinguished by doubly cross-barred marking ; the latter, which border these, by singly cross-barred, with a cross in the small squares. The several areas of the two combined formations are as follows : I. The Acadian : covering part of western Newfoundland, of Nova Scotia, and of New Brunswick. II. The Rhode Island: covering part of Rhode Island, and extending northward and eastward into Massachusetts. III. The Worcester area : about Worcester, Massachusetts. IV. The Michigan area : occupying the larger part of Michigan between the southern half of Lake Huron and Lake Michigan, having the coal- measures over its central portion. V. The Pennsylvania- Arkansas area : stretching in a zigzag way over 25 degrees of longitude and 12 of latitude ; first, from the southern border of western New York, and a line just south of Lake Erie, to Alabama and Mississippi; then, northward and westward to Illinois and Iowa; thence southward and westward again to Arkansas and Texas. At the western limit commences the "Western Interior Sea," where the Carboniferous strata pass out of sight beneath those of the Cretaceous. The coal-measures of this area are mostly in three parts, underlaid and connected by the Subcar- boniferous. These parts are thus separate, either because never united, or more probably because of the removal of the coal-measures that once covered the intermediate Subcarboniferous beds. VI. Over the Western Interior and along the summit region of the Rocky Mountains, but without coal, and mostly as a limestone wherever there are outcrops. VII. Along parts of the Great Basin, being a constituent of many of the mountain ridges; also in the Sierra Nevada, and in other portions of the Western border region. VIII. In the Arctic regions, along a wide belt between the parallels of 72 and 821, northeast in course, from Banks Land on the west to Grinnell Land on the east, and reaching beyond the latter to 83, nearly the most north- ern point of Arctic exploration. Also on Spitzbergen and Bear Island. The Coal-measures, or the areas of the Carboniferous period, have a smaller range, and the productive Coal-measures, a still smaller. Of the above eight regions, only numbers L, II., IV., and V., to the east of the meridian of 100 W., are coal-producing ; but the Arctic beds of Grinnell Land afford coal, which may be available whenever the seas shall become navigable. The term Permo-Carboniferous is sometimes used for the beds of the Car- boniferous and Permian periods of central and eastern North America, because they make an essentially undivided series. 636 HISTORICAL GEOLOGY. 1. SUBCARBONIFEROUS PERIOD. ROCKS KINDS AND DISTRIBUTION. The Subcarboniferous period, like several other periods of the Paleozoic, is noted for extensive limestone formations with thin shales and sandstone over the Central Continental Interior, or the area of the Mississippi basin ; for sandstones and shales, with little limestone, along the Eastern Interior region, especially its northern bay-like portion ; and, like all the preceding periods after the close of the Lower Silurian, for no deposits yet known over the Atlantic continental border south of the latitude of New York. The peculiarities of the Eastern Interior are attended by another distinctive feature: The limestones of the Mississippi basin abound in fossils, especially Crinoids, Brachiopods, and Corals ; and, owing to the Crinoids, they are often called Crinoidal limestones ; while the fragmental rocks to the eastward con- tain fewer fossils, and almost all of these are of different species from the western, except where limestone occurs in the series. Owing to the wide differences in the rocks and fossils, there is much difficulty in bringing the beds of the two distant regions into parallelism. The rocks of the lower of the two groups in Pennsylvania, the Pocono, are mainly beds of hard gray sandstone and conglomerate; and those of the upper, the Mauch Chunk, reddish shales and shaly sandstones. In south- western Pennsylvania a thin bed of siliceous limestone makes the top of the Pocono, and a similar layer occurs also in the upper shales. The enduring Pocono sandstone is 800 feet thick near Pottsville, Pa. It extends northeastward, capping at many points the high northern plateau of the state ; and it also stretches southwestward, making the summit, in Bedford County, of the Alleghanies, where it is 1400 feet thick holding its place against denuding agencies. It is supposed, by Lesley, to constitute some hundreds of feet of the higher peaks of the Catskills. The overlying Mauch Chunk shale is a fragile rock and was easily swept off by denuding waters from the Pocono floor. Its thickness is stated to be 3000 feet at Pottsville. The two formations thin down to 600 feet, in southwestern, and 300 feet in northwestern, Pennsylvania. The thickness of the limestone layers of the Eastern Interior increases in West Virginia; and in the southwest counties of Virginia becomes rather abruptly over 2000 feet thick. Farther south, in Tennessee and Alabama, siliceous beds and cherty limestones make the chief parts of the formation, and they once covered the Silurian limestone basin of central Tennessee. Some thin beds of coal occur in the upper formation, and one in southwest Virginia, near New Biver, is worked. In Ohio, about 600 feet of shale and sandstone are overlaid in some parts by 15 to 20 feet of limestone. In Michigan, the beds are chiefly shales and limestones, with less than 70 feet of limestone in the upper part. The limestones of the Mississippi basin, with the included shales and sand- PALEOZOIC TIME CARBONIC. 637 stone, constituting the Mississippian group of Williams, have an aggre- gate thickness in southwestern Illinois of 1200 to 1500 feet. They thin out northward in this state before reaching Eock Island County ; and beyond, the coal-measures rest on the Devonian. These limestones extend in part into Iowa, Indiana, Kentucky, Missouri, and southward into Texas. The Kinder- hook group extends far into Iowa; but after its deposition a long retreat of the shore line took place before the Burlington beds, the first part of the Osage group, were deposited ; and this retreat was continued after the deposit of the Burlington group. But before the St. Louis epoch began there was a sub- sidence, allowing of an advance again northward, as the northward extension of the beds shows. There is thus unconforinability by overlap of the St. Louis limestone over the underlying beds, as stated by C. A. White (1870, Eep. Iowa). The subdivisions of the Mississippian group in Illinois and the adjoining parts of the Central Interior area are arranged as follows by C. K. Keyes (G. S. A., 1892): 1. The Kinderhook Group. This group was so named by Meek and Worthen (1861). The "Lithographic limestone," "Vermicular sandstone and shales," and " Chouteau lime- stone " of Missouri, are three rather persistent divisions. The term Louisiana, from a place in Pike County, Mo., is used by Keyes in place of Lithographic, and Hannibal shales for Vermicular sandstone and shales. The "Louisiana" limestone is 60' thick in Missouri. The Hannibal shales are reported from Iowa, as well as Missouri, with a thickness of 70' to 150' or more. The Chouteau is a fine buff-colored limestone, 10' to 15' thick at Hannibal and Louisiana, 100' or more at Sedalia, in Missouri, and perhaps 50' at Burlington, Iowa. The Goniatite limestone of Rockford, Ind., was referred to the horizon of the Chouteau by Meek. The larger part of the " Knobstone group " of sandstones and shales (partly calcareous), which makes the eastern border of the Carboniferous area of Indiana, is referred to the Kinderhook. 2. The Osage Group. The subdivisions of the Osage group so named by H. S. Williams are: (1) Lower Burlington, (2) Upper Burlington, (3) Keokuk, with the "geode-bed" and the Warsaw shales and limestone. The Lower Burlington is described as having Crinoids of delicate forms ; the Upper, of stouter forms ; the Keokuk, of still coarser and larger kinds, massive in construction. The geode-bed is a bed of blue shale, 30' to 35' thick, containing thin layers of limestone. The geodes are sometimes 2' in diameter ; they contain within : quartz crystals, agate, crystals of calcite, dolomite, and often pyrite, sphalerite, millerite (in hair-like needles, or tufts of needles), besides other minerals. An extermination of a large part of the Keokuk species occurred at the close of the epoch. 3. The St. Louis Group. The St. Louis limestones were so named by Shumard from the evenly bedded limestone of St. Louis, Mo. They are oolitic 3 miles above Alton. The northern limit in north-central Iowa, near Fort Dodge, is the evidence of the north- ward return of the shore line for several hundred miles beyond the limit of the Keokuk, and here the beds are fossiliferous marls. In St. Genevieve County, Mo., the thickness of the beds is over 300', and it is still greater to the southeastward. The rock at Spergen Hill, Ind., is of this division. 4. The Chester or Kaskaskia Group. This group includes limestone, in three or four beds, with intercalated shale and sandstone, aud sandstone below ; it is occasionally 800' thick. It comprises the " Pentremital " limestone, and the "Upper Archimedes" limestones, called also the "Kaskaskia" limestone. The stratum of sandstone at the 638 HISTORICAL GEOLOGY. bottom is the ferruginous sandstone of Shumard. The sandstone is regarded by C. R. Keyes as having been made while a final retreat of the shore line was in progress. He names it the " Aux Vases" sandstone. The section of the Subcarboniferous at Burlington, Iowa, includes : (1) of the Kinder- hook, 50'+ of clay shale ; (2) 20'- 30', soft shaly sandstone ; (3) gray impure limestone, often oolitic below, 9'- 13'; (4) fine sandstone, 6'; (5) gray oolyte, 4'; (6) buff limestone, 5', of the Lower Burlington ; (7) brown and gray encrinal limestone, 27'; (8) buff calcareous and siliceous shales, with thin limestone layers and chert, 23', of the Upper Burlington ; (9) gray encrinal limestone, somewhat cherty, 30'; (10) impure limestone with chert nodules and seams, 20' (Keyes). The Keokuk exposures include about 100' of Keokuk below and above Warsaw and St. Louis beds. Keyes has further reported (Dec., 1892) the discovery, in northeastern Missouri, of a bed of the Kinderhook limestone, containing its typical fossils, and these chiefly Mollusks, intercalated in the overlying Burlington group, where typical in its fauna, and this chiefly crinoidal, and without a change in lithological characters or the purity of the limestone beds. It shows, as Keyes observes, that the Kinderhook and Burlington stages were not wholly successive as regards time ; that after the Burlington group had made progress, the Kinderhook species still existed, for a while at least, outside of their former limits, but ready to return when the conditions favored. In Missouri, the whole thickness of the Sub- carboniferous limestone is 1150'. In Indiana, the " Knobstone," below the Keokuk, has a thickness in some places of 500', the Keokuk of 100', the St. Louis of 330', and the Chester of 75'; the latter consists of sandstones alternating with limestones. In Lawrence County, an irregular bed, or series of pockets, of porcelain clay, ranging to 6' in thickness, lies at the top of the Chester limestone, over a bed of iron ore. About a third is of pure white color. It has been called indianaite; with it occurs the mineral allophane. In Michigan, the Subcarboniferous consists of four groups of strata, according to A. Winchell: (1) or lowest, 173' of grit and sandstone, called the Marshall Group; (2) 123' of shale and sandstone, the Napoleon Group ; (3) 184' of shale and marlyte, with some limestone and gypsum, the Michigan Salt-group ; (4) the Carboniferous limestone, 66' thick. This limestone is well exposed at Grand Rapids. The Marshall group is made the equivalent, in part, of the Kinderhook; and the limestone, at the top, the equivalent of the Chester and St. Louis groups. In Ohio, the Subcarboniferous beds comprise the Waverly group. In northwestern Pennsylvania, the Subcarboniferous is in the main equivalent to the Waverly. I. C. White has recognized three divisions : (1) the Oil-creek group, the equiva- lent, it is believed, of the Pocono ; (2) Meadville group ; and (3) Shenango group. In Warren County, the Panama conglomerate is more than 200' below the top of the Che- mung, and may be recognized by abundant remains of Ptychopteria. The Waverly con- sists of shaly sandstones in its lower third, followed by a conglomerate (= Sub-Olean ?) above which are thin-bedded buff sandstones. In West Virginia, the Lower Subcarboniferous occurs along the middle portion of the main Alleghany Mountains, from the Potomac southward. In Greenbrier County, near the White Sulphur Springs, it includes a stratum of limestone 822' thick, with 1260' of shales and sandstone. The limestone to the north, in Monongalia County, was found by Meek, through its fossils, to be the probable equivalent of the Chester group. In middle Tennessee, according to Safford, the Siliceous group consists, commencing below, of (1) the Protean beds, cherty and argillaceous, with some limestone, 250' to 300', and (2) the Lithostrotion or Coral beds, an impure cherty limestone, the equivalent of the St. Louis limestone, about 250' thick. The Upper member is limestone, 400' thick on the northern borders of the state, an& 720' on the southern. These two divisions occur also in eastern Kentucky. The Upper member also extends into the northeast corner of Mississippi, where it is overlaid by Cretaceous beds (Hilgard). At Huntsville, Ala., PALEOZOIC TIME CARBONIC. 639 Worthen found it to consist principally of gray limestone, partly, oolitic, partly cherty, with some shaly beds, in all about 900'. The larger portion of the series yields Chester fossils ; but characteristic forms of the St. Louis group mark the age of the lowest 250' to 300'. In Nova Scotia and New Brunswick, the Subcarboniferous rocks are : (1) the Horton series, consisting of red sandstones, conglomerates, red and green marlytes ; and, above these, (2) the Windsor series, consisting of thick beds of limestone, full of fossils, with some red marlytes, and beds of gypsum, affording the gypsum exported from Nova Scotia and New Brunswick. Thus the upper part is calcareous, as in Ohio, Tennessee, and West Virginia. The estimated thickness is 6000'. To the north, toward the Archsean, the limestones fail ; and, instead, the rocks are to a greater extent a coarse conglomerate. To the south, limestones prevail. The best exposures of the lower or Horton series are at Horton Bluff, Hillsborough, and other places in southern New Brunswick. In the lower part of these Subcarboniferous beds, as in those of Virginia, there are, on a small scale, "false" Coal-measures, and, in one instance, a bed of erect trees, under- clays, and thin coal seams ; and the same beds contain numerous remains of fishes. The fish-bearing shales of Albert Mine, New Brunswick, are of this period (Dawson) . Rocky-Mountain and Pacific-border regions. Over large portions of these regions, the limestones of the Subcarboniferous have not been distinguished from those of the following period. In most cases their recognition only waits for the more careful study of the fossils ; but, at many points, these appear to be wanting. They have been identified in the Elk Mountains, and other ranges of the crest chain of the mountains in western Colorado ; on the eastern slopes of the Wind River Mountains, in Wyoming. In Montana, at "Old Baldy," near Virginia City, tiiere are fossils of the Chester group, and probably the Lower Subcarboniferous beds are also present (Meek). In Idaho, near Fort Hall, Bradley found masses of limestone filled with minute shells, many species of which Meek has identified with forms characteristic of the oolitic beds of the St. Louis group, at Spergen Hill, Ind. LIFE. PLANTS. The vegetation of the period included species of Lycopods of the genera Lepidodendron, Sigillaria, Knorria ; Ferns of the Devonian genera, Archceopteris, Neuropteris, fiphenopteris, Odontopteris, with spe- cies also of the new genera Alethop- teris, Lesley a ; Equiseta of the genera Calamites, Sphenophyllum, and Aste- rophyllites; and Cycads, under Gym- nosperms, of the genus Cordaites ; and among the fossil fruits, those of Cordaites, and probably some of Conifers of the Yew family. ANIMALS. 1. Spongiozoans. Several sponges have been described of the genera Palceacis (which has deep cup-like cavities), Physospon- gia, etc. Hexactinellid sponges are common in the beds at Crawfords- ville, Ind. The chert, which occurs in many beds, abounds in sponge spi- cules. 991. 991 a. POLYP-CORAL. Fig. 991, portion of the Coral, Litho- strotion Canadense ; 991 a, vertical view of the same. Meek and Worthen. 640 HISTORICAL GEOLOGY. 2. Actinozoans, Echinoderms. The animal life was remarkable for the abundance of a species of Lithostrotion, represented in Fig. 991, and for a great profusion and diversity of Crinoids. This Lithostrotion is often colum- nar in the external form of parts of masses (as shown in Fig. 991 a), although essentially a massive coral. Among other Corals the old genera Zaphrentis and Cyatliopliyllum have their species, but not Favosites, Michelinia, Gysti- phyllum, Dipliypliyllum, Sarcinula, and others that were common in the De- vonian. Species of Lithostrotion have been found in the Arctic lands between Point Barrow and Kotzebue Sound. 992-1003. ECHINODERMS. Fig. 992, Scaphiocrinus Missourieasis ; 993, Actinocrinus proboscidialis ; 994, Dorycrinus unicornis ; 995, Woodocrinus elegans ; 99 X 6, Batocrinus Christyi ; 997, Platycrinus Saffordi ; 998, the proboscis of Batocrinus longirostris ; 999, Pentremites pyriformis ; 1000, 1000 a, P. Godoni ; 1000 a, top view ; 1001, portion of the shell of Archseocidaris Wortheni ; 1002, spine of A. Shumardiana (x 2); 1002 a, base of spine ; 1003, id. of A. Norwoodi. Figs. 992-995, 99T-1003, Hall ; 996, Swallow. The number of species of Crinoids described from the American Sub- carboniferous limestone exceeds 650. Some of the forms are represented in Figs. 992 to 1000, but mostly wanting the arms and stem, as is common with these fragile species. Fig. 995 represents the perfect body of Woodocrinus elegans, with the arms closed together, and, below, a few segments of the pedicel, which, entire, may have been a foot long; 992 is a Scaphiocrinus, with the arms broken. In Poteriocrinus Coxanus Worthen, t{ie arms are six inches long, and the breadth of the expanded Crinoid must have been nearly PALEOZOIC TIME CARBONIC. 641 a foot. Figs. 993, 994, 996, 997 are the bodies of different species of Crinoids without the radiating arms. The Crinoids often have a long or short pro- boscis-like projection, at the center above, which is made of stout calcareous pieces like the body, out is tubular; it is seen broken off in Figs. 993 and 996; and Fig. 998 represents one separate from the body of a Batocrinus (near that of Fig. 996), showing the calcareous pieces constituting it. Fine figures of the Subcarboniferous Crinoids, illustrating the wonderful diversity of forms among them, are contained in the Illinois, Iowa, and Ohio geologi- cal reports. In some species the length and form of the proboscis (which contains the anal or excretory tube, not that to the mouth) are very re- markable. Two species of Pentremites, armless bud-shaped, five-sided species, of the tribe of Blastoids, eminently characteristic of the Subcarboniferous, are rep- resented in Figs. 999, 1000. 1004. 1005. ECHINOIDS. Fig. 1004, Oligoporus nobills (x ) ; 1005, Melonites multiporus, view of top (x 2). Meek and Worthen. Echinoids were of large size, and were unlike modern species in the excessive number of vertical series of plates between the ambulacral areas. One species (Fig. 1004) has 5 series of these plates, instead of the normal or modern number, two. In Archceocidaris (a portion of a shell of one species of which is shown in Fig. 1001), the spines with which the shell was bristled were (as in modern species of Cidaris) of large size and few (like Fig. 1002 in form), as the large prominences over the shell (Fig. 1002 a) indicate; but in Fig. 1004 they were very small. Fig. 1005 is a top view, enlarged, of Melonites multiporus. One very large slab in the Yale Museum, from St. Louis, Mo., contains 11 Melonites to a square foot. The generic name alludes to the resemblance in form to a melon. 3. Molluscoids. Of Molluscoids, the screw-shaped Bryozoans, species of Archimedes, Fig. 1006, are characteristic. The screw has lost the larger DANA'S MANUAL 41 642 HISTORICAL GEOLOGY. 1006. 1007. part of the .blade, the part that carries, on its under surface, the cells occupied by the animals, as illustrated in Figs. 1007 a and 1007 b. Brachiopods were numerous, especially of the genera Productus (Fig. 1013), Chonetes (Figs. 1012, 1015), Spirifer (1010, 1014), Athyris, Dielasma and Rhynchonella. There were also species of the Lower Silurian genus Orthis (Fig. 1008), but none of Stropheodonta, Merista, Meristella, so well rep- resented in the Devonian. 4. Mollusks. Among Mollusks, Lamelli- branchs were common. Under Gastropods, the genus Bellerophon, which first appears in the Cam- brian ; the Lower Silurian genera, Euomphalus, Murchisonia, Pleurotomaria, and the Upper Si- lurian Platyceras, Loxonema, and Macrocheilus, which had many Devonian species, were still well represented. The shells of Platyceras are often attached to a Crinoid, like those of a modern Crepidula to an oyster. Cephalopods were of many kinds under the old genus Orthoceras; and Discites, Goniatites, Gyroceras, had their species. Nautilus (Endolobus of Hyatt) spectabilis M. and W., from the Chester limestone, was two feet in BRYOZOANS. Figs. 1006, 1007 a, 6, Archimedes Wortheni (1007 a and 10076, xf). Hall. 1008 1008-1015. 1011 1014 BEACHIOPODS. 1008, Orthis Michelini var. Burlingtonensis ; 1009, Spiriferina spinosa ; 1010, Spirifer increbes- cens ; 1011, Eumetria Verneuiliana ; 1012, Chonetes Illinoisensis ; 1013, Productus punctatus ; 1014, Spirifer biplicatus ; 1015, 1015 a, Chonetea ornatus. Figs. 1008-1011, Hall ; 1012, Koninck ; 1013, Meek ; 1014, 1015, Swallow. diameter; Orthoceras nobile M. and W., of Illinois, was five to six feet long, and a foot in diameter; and Gyroceras Burlingtonense Owen, five inches in diameter. The species represented in Figs. 1016, 1017 are from the Goniatite bed of Rockford, Ind. PALEOZOIC TIME CAKBONIC. 643 5. Crustaceans. TriloUtes were of twenty or more species, all small prini- looking forms, of the Devonian genera Proetus, Phcethonides, and the related, but low-featured, Carboniferous genera Griffith! des and Phillipsia. Half of the twenty species are of the genus Phillipsia. The other Crustaceans known from the beds are Phyllopods and Ostracoids; and the shells of a Beyrichia make the chief part of the material of a layer four feet thick, north of Pella, Iowa. 1016. 1016 a. 1017. CEPHALOPODS. Fig. 1016, Goniatites Oweni; 1016 a, id., outline, showing direction of septa; 1017, G. (Pro- lecanites) Lyoni ; 1017 a, id., direction of septa. Hall. 6. Insects. Remains of Insects, and other terrestrial species, are neces- sarily rare in marine deposits, and no species have yet been reported. 7. Vertebrates. Vertebrates were represented by Ganoids and Selachians, as in the Devonian, but with apparently no Placoderms. There were also the first yet known of Amphibians. The remains of Selachians are teeth and fin-spines. The teeth are either of the pavement kind, allied to those of the living Cestracion (or Port Jack- son Shark), and to Myliobatis (or Eagle Ray), or of pointed and triangular form, more or less resembling some of the modern type referred to the Hybodont and Petalodont families. Of the pavement-mouthed forms, the Cochliodonts, which have a large massive plate on either ramus of the jaw, were numerous in the Subcarbo- niferous. One of these plates is represented, natural size, in Fig. 1018, from Worthen's Illinois Report; and the form for the whole jaw in a foreign species is shown one third the natural size in Fig. 1019. Over 50 species are described from the Illinois limestone. The Psammodonts, having the inner surface of the jaw covered by flat rectangular plates, nearly as in Myliobatis, have over a dozen Subcarboniferous species of the genera Psammodus and Copodus. A Petalodont tooth, Petalodus curtus, has been reported from the 644 HISTORICAL GEOLOGY. Keokuk limestone. The Cestracionts (see page 416), with a rough, uneven pavement, were represented by species of Helodus and Orodus. Some of the sharp-pointed teeth of Hybodonts are shown in Figs. 1020-1022 (Newberry and Worthen) . 1018. 1019. TEETH OF CESTRACIONT SHARKS. Fig. 1018, Cochliodus nobilis ; 1019, C. contortus (x ). Fig. 1018, Meek ; 1019, Agassiz. Fin-spines of Sharks are various in size and form. One, of Ctenacanthus, has a length of a foot; and others, now broken, were probably 6 inches longer ; they indicate fins of large size, and therefore the existence of great Sharks. 1020. 1021. TEETH OF SHARKS. Fig. 1020, Carcharopsis Wortheni ; 1021, Cladodus spinosus ; 1022, Orodus mammillaris. Newberry. Amphibians are known from their footprints on a layer of the Mauch Chunk shale near Pottsville, in Pennsylvania, as described by Isaac Lea. A reduced view of the slab is shown in Fig. 1023. There is a succession of six steps, along a surface little over five feet long; each step is a double one, as the hind-feet trod nearly in the impressions of the fore-feet. The prints were hand-like; that of the fore-foot five-fingered and four inches broad; that of the hind-foot somewhat smaller, and four-fingered. That the Amphibian was therefore large, is also evident from the length of the stride, which was thirteen inches, and the breadth between the outer edges of the footprints. PALEOZOIC TIME CARBONIC. 645 eight inches. There is also a distinct impression of a tail, an inch or more wide. The slab is crossed by a few distinct ripple-marks (eight or nine inches apart), which are partially obliterated by the tread. The whole sur- face, including the footprints, is covered throughout with rain-drop impressions. Tracks of Sauropus primaevus (x J). I. Lea. We thus learn that in the region about Pottsville a mud-flat was left by the retreating waters, perhaps those of an ebbing tide, covered with ripple- marks; that the ripples were still fresh when a large Amphibian crossed the flat ; that a brief shower of rain followed, dotting with its drops the half-dried mud ; that the waters again flowed over the flat, making new de- posits of detritus, and so buried the records. The records were opened and deciphered in 1849 by Dr. Lea. Char act e ristic Species . PLANTS. In the Subcarboniferous of Pennsylvania occur, according to Lesquereux, Archceopteris obtusa Lx., and A. minor Lx. (both found in the Chemung of the Devonian) , A. Bockschiana Gopp.; remains of Lepidodendron, as L. corrugatum Dn., and Stigmaria minuta Lx. ; in Illinois, in the Chester group, the Ferns Megaphyton protuberans Lx., Caulopteris Wortheni Lx., Alethopteris Helena? Lx., Neuropteris capitata Lx., Pseudope- copteris anceps Lx., Rhacophyllum flabellatum St., Sphenopteris cristata St., Megalopteris fasciculata Lx. ; also Lepidodendron costatum Lx. , L. turbinatum Lx., L. obscurum Lx., L. Veltheimanum St., L. Wortheni Lx., Stigmaria anabathra Corda, S. minor Gopp., S. umbonata Lx., Knorria imbricata St., Calamites Suckovi Bngt., Asterophyllites equiseti- formis Schl. , and others. In the Chester group of Indiana, according to Collett, occur Stigmaria, Lepidodendron aculeatum St., L. diplostegioides Lx., L. forulatum Lx., Lepidostrobus, Knorria, Neurop- teris biformis, Alethopteris, etc. One specimen of Lepidodendron had portions of the leaves attached to the stem, which were 12 to 14 inches long, though only from one eighth to one fourth of an inch in width. In the Subcarboniferous of Nova Scotia and New Brunswick, Dawson has made out the following species: FERNS Cyclopteris Acadica Dn. , Cardiopteris, Hymenophyllites ; LYCOPODS Ptilophyton plumula Dn., the last of the genus, Lepidodendron corrugatum Dn. (near L. Veltheimanum of Europe), L. tetragonum St., L. obovatum St., L. dichoto- 646 HISTORICAL GEOLOGY. mum St., L. aculeatum St., also Stigmaria ficoides Brngt., Cordaites borassifolius St., Dadoxylon antiquum Dn. The metamorphic Carboniferous region of Worcester, Mass. , where the slates are mica schist, have afforded I. H. Perry specimens of Lepidodendron (Sagenaria) acuminatum G6pp., as identified by Lesquereux {Am. Jour. Sc., xix., 1885). It is doubtful whether the plant is Subcarboniferous or Carboniferous. See, further, Pa. G-eol. Rep., No. P. ; III. Geol. Hep., vols. ii. and iv. ; Ind. Geol. Rep. for 1883 ; Damson's Hist. Plants, 1888, etc. ANIMALS. 1. Rhizopods. Endothyra Baileyi H. occurs in the St. Louis limestone of Indiana. 2. Spongiozoans. The hornstones of the limestones in Illinois and Indiana abound in microscopic spicules of sponges, with a few Desmid-like forms similar in general to those of the Corniferous limestone (page 583) (M. C. White). Palceacis (Sphenopterium} obtu- sus M. & W., Keokuk limestone, P. Cuneiforms M. Edw., St. Louis limestone. In the Keokuk occur many Hexactinellid sponges of the genera -Hydnoceras, Physospongia, Phragmodictya. 3. Actinozoans. Fig. 991, Lithostrotion Canadense Castelnau, St. Louis 1. ; L. pro- liferum H., St. Louis group; Zaphrentis spinulosa E. & H. ; Z. minas Dn., West Kiver, Pictou ; Cyathophyllum Billingsi Dn., Nova Scotia. 4. Echinoderms. (a) Blastoids : Fig. 999, Pentremites pyriformis Say, Kaskaskia 1. ; 1000, P. Godoni Defr., ibid., and 50 other species of this and the related genera Granato- crinus and Troostocrinus. (6) Crinoids. Fig. 992, Scaphiocrinus Missouriensis Shum., St. Louis 1. ; 993, Acti- nocrinus proboscidialis H., Burlington 1. ; 994, Dorycrinus unicornis Owen & Shum., ibid. ; 995, Woodocrinus elegans H., ibid.; 996, Batocrinus Christyi Shum., arms broken off, ibid. ; 998, proboscis of Batocrinus longirostris H., ibid. ; 997, Platycrinus Saffordi Troost, side-view, Keokuk 1. The most prolific locality of Crinoids, as yet known, is Burlington, Iowa, where over 350 species, representing over 50 genera, were collected by Mr. C. Wachs- muth, besides 6 Echinoids, 4 Asterioids, and 1 Ophiuroid. Many of them are described by Hall in his Iowa report of 1858. The Keokuk beds of Crawfordsville, Ind., have yielded 50 species. The genera most numerously represented are Actinocrinus, Cyathocrinus, Dichocrinus, Batocrinus, Platycrinus, Poteriocrinus, Scaphiocrinus, and Zeacrinus. (o) Echinoids. Fig. 1001, Archceocidaris Wortheni H., St. Louis 1. ; 1002, A. Shumar- dana H., St. Louis 1. ; 1003, plate of A. Norwoodi H., Chester 1. ; 1005, Melonites mul- tiporus 0. &N., St. Louis 1. ; 1004, Oligoporus nobilis M. & W., Burlington 1. Figs. 1004, 1005 are from Worthen's Report on the Geology and Paleontology of Illinois. (d) Asterioids and Ophiuroids. Worthen and S. A. Miller have described (in III. Rep., vii., 1883), from Illinois, Compsaster formosus, Chester limestone; Cholaster pecu- liaris, ibid., and the Ophiuroid Tremataster disparilis, ibid. 5. Molluscoids. (a) Bryozoans. Fig. 1006, Archimedes Wortheni H., being a portion of the spiral axis, with the reticulated expansion of the spiral worn off. Fig. 1007 a, a por- tion of the reticulated expansion, magnified and showing the upper surface. Fig. 1007 b, the under or cell-bearing side of the same. (6) Brachiopods. Kinderhook : Spirifer Cooperensis Swallow ; 8. Marionensis, Chonetes ornatus Shum. (Fig. 1015), 1015 a, surface enlarged, Lithographic and Chouteau limestone, Mo. ; 1014, Spirifer biplicatus H. Burlington 1. : 1008, Orthis Michelini L'Eveille (var. Burlingtonensis H.), Spirifer Meeki, S. Logani, Productus Flemingi Sow. Keokuk 1. : Actinoconchus planosulcatus Phill., 111., Chonetes planumbonus M. & W., Iowa, Camarophona subtrigona M. & W., 111., etc., Spirifer Keokuk H. St. Louis 1. : Productus scitulus M. & W., 1011, Eumetria Verneuilana H., Warsaw, Spiriferina spinosa N. & P., Warsaw, Lower Archimedes, Mo. Chester 1. : 1010, Spirifer increbescens H., Kaskaskia PALEOZOIC TIME CARBONIC. 647 limestone, Spirifer glaber var. contractus M. & W., 1009, Spiriferina spinosa ; 1012, Chonetes lllinoisensis W., Productus parvus M. & W. (c) Lamellibranchs. Kinderhook 1. : Cardiopsis radiata M. & W. Burlington 1. : Aviculopecten Burlingtonensis M. & W., Iowa. Keokuk 1. : Aviculopecten Oweni, A. oblon- gus, A. amplus, of M. & W., 111. St. Louis 1. : Myalina concentrica M. &. W., Nucula Shumardana H., Warsaw, Idaho, N. nasuta H., ibid., Conocardium Meekanum H., ibid. Chester 1. : Pinna Missouriensis Swallow, 111., Myalina angulata M. & W., 111., Schizodus Chesterensis M. & W., 111. (d) Gastropods. Kinderhook 1. : Straparollus lens H., Goniatite bed, Ind., Bellero- phon cyrtolites H., ibid. Burlington 1. : Platyceras reversum H., Iowa. Keokuk 1. : Pleurotomaria Shumardi M. & W., 111., Platyceras equilaterale H., Iowa. St. Louis 1. : Dentalium venustum M. & W., 111., Straparollus similis M. & W., Spergen Hill, Ind., S. Spergensis H., ibid. 6. Vertebrates. Fishes. The species of American Subcarboniferous Fishes have been described mainly by Newberry, Newberry and Worthen, and St. John and Worthen in the Ohio and Illinois Geol. Reports. The species described by Newberry and Worthen, from Illinois specimens, include 16 of Hybodonts, 26 of Petalodonts, 52 of Cestracionts, with 9 of fin-spines and Psammodonts. St. John and Worthen have added over 50 species of Cochliodonts, a dozen of Psammodonts, and over 20 kinds of fin-spines (III. Geol. Rep., vol. vii., 1883). Fig. 1018, tooth of Cochliodus noUlis N. & W., 111. ; 1021, Cladodus spinosus N. & W., St. Louis 1., Mo. ; a, section of the same ; 1020, Carcharopsis Wortheni Newb., Huntsville, Ala.; 1022, Orodus mammillaris N. & W., Warsaw, 111. The Subcarbo- niferous at Ogden has afforded a tooth of a species of Dendrodus. 2. CARBONIFEROUS PERIOD. Since the Carboniferous .period, or that of the Coal-measures, was a period largely of marshes, as it opened the land gradually became emerged; and the first rocks that were laid down bear evidence, in many regions, of the change of condition by their beach-like character. Other evidence of the transition epoch exists in erosions over the Subcarboniferous rocks, making a surface of hills and depressions for the reception of the later depositions. Part of this irregularity may be the work of denudation before the Subcarboniferous period had closed; but other parts are referred to the time of emergence. ROCKS SUBDIVISIONS, KINDS, AND DISTRIBUTION. The most prominent subdivisions of the Carboniferous formations are those of (1) the Millstone grit, or the Great conglomerate, named, in Penn- sylvania, the POTTSVILLE CONGLOMERATE; and (2) the COAL-MEASURES. THE POTTSVILLE CONGLOMERATE. The conglomerate beneath the coal-measures is generally a hard gritty siliceous rock, made of quartzose gravel or sand a rock that was literally a millstone grit early in the century. It has a thickness of 800 to 1700 feet in the center of the Anthracite region of Pennsylvania, but thins northward in this state to less than 300 feet in the Wilkesbarre region, and westward to 200-300 feet. Its lower part spreads northward into western New York and constitutes there the " Olean conglomerate " of Alleghany and Cattaraugus counties, the rock of " Rock City," 25 to 60 feet thick. It extends westward 648 HISTORICAL GEOLOGY. through Ohio, Kentucky, Indiana, and beyond ; but is mostly a sandstone, where present, in the Mississippi basin. But even there, beach-like features are often observed. Like the coal-beds of the Coal-measures the formation was only approximately at a common level. In part of western Pennsylvania the Pottsville conglomerate contains one or more coal-beds. Just above the Sharon conglomerate, the base of the Pottsville series in Mercer County, Pa., one coal-bed is two to four feet thick, and has long been worked. The same bed is mined also in Ohio. A bed of similar character occurs in the conglomerate of Kentucky, Tennessee, and Alabama, and that of Alabama affords excellent coal. These coal-beds, with their alternating beds of shale, prove that slow and varying changes of level were in progress, but that for prolonged intervals portions of the surface lay quiet until deep accumulations of vegetable debris had been made in the marshes. The fact of a general parallelism in the movements over Europe and America favors the view that the changes in level and in deposits were a consequence, in a general way, of oscillations in the sea level, that is, in the crust of the sea bottom ; but at the same time there were other variations in level which were dependent on local conditions and movements over the continents. THE COAL-MEASURES. The Coal-measures in Pennsylvania are divided into (1) the LOWER PRO- DUCTIVE MEASURES, (2) the LOWER BARREN MEASURES, (3) the UPPER PRODUCTIVE MEASURES. Above the last there are the Upper Barren Measures, corresponding to the Permian. Over the great Appalachian- Arkansas area, the three great Carboniferous or Coal-measure regions are, as shown on the map, page 412, (1) the Appalachian, extending from northern Pennsylvania to Alabama, and having the Anthracite region as a detached portion in eastern Pennsylvania; (2) the Illinois-Indiana) east of the Mississippi, extending south into Kentucky; and (3) the Iowa-Texas, west of the Mississippi. The Appalachian area spreads west into Ohio, eastern Kentucky, eastern Tennessee, and northern Alabama. In Tennessee, the Cumberland Table- land has the Coal-measures for the top, and a substructure of Subcarbonifer- ous rocks, 1000 feet or more thick, for the rest of its height. In Alabama, the western portion, constituting the large Warrior coal-fields, is a continuation of the Cumberland Measures, with an extension far westward nearly to the Missis- sippi line Mississippi having only a small patch of Subcarboniferous beds. It is probable that the Coal-measures of Tennessee, and those of Alabama, originally spread across what is now the Mississippi valley and joined the area of southern Missouri. The Carboniferous areas are generally much broken, especially so in Pennsylvania and along the Appalachians to the southwest of this state. The following map, by Lesley, illustrates in a general way the condition in Pennsylvania. The Anthracite coal is in narrow isolated strips to the east- PALEOZOIC TIME CARBONIC. 649 ward, among upturned rocks ; and the Pittsburg coal at the west end of the state, although among nearly horizontal rocks, also has its outlying patches. Oeological investigation has proved that the two distant areas were once 1024. Map of part of Pennsylvania, showing the coal areas of the state, in black; the Anthracite beds east of the Susquehanna, and the Bituminous beds to the westward. united and that the coal once covered 10 times its present area. " Broad Top" in southwestern Pennsylvania is shown by Lesley to be a fragment of the Pittsburg coal-bed, about 80 square miles in area, left in the general denudation of the Appalachian region. 1025. Section of the Panther Creek Anthracite basin at Nesquehoning tunnel. Figs. 1025 to 1027 represent sections of portions of the Anthracite region, showing the character of the flexures that led, through denudation, to the breaking of the coal-beds into nearly parallel belts. Fig. 1025 is a vertical 650 HISTORICAL GEOLOGY, section from the heart of the Anthracite region, between Nesquehoning Valley on the west (left in section), and Mauch Chuuk. It is from the- Report of C. A. Ashburner, of the Geological Survey of Pennsylvania. The length is about 1200 yards (the scale of the figure being 1000 feet to the inch). The flexures to the west have their summits pushed westward 40 beyond the vertical. The folded rocks consist of beds of Anthracite, and intervening strata of shale and sandstone ; and the Anthracite beds include the great "Mammoth bed" (lettered at its outcrop E, E, 1 E 2 ), which is 13 to 27 feet thick, and the bed F (outcropping at F, 1 F, 2 F, 3 F, 4 F 5 ), 11 to 20' feet thick, besides one of eight to nine feet. The Mammoth bed " is doubled on itself at E 1 . Fig. 1026, from Lesley, is from the Anthracite 1026. Section on the Schuylkill, Pa.; P, Pottsville, on the Coal-measures (14). Lesley. region of Pottsville, about 30 miles south of west of Mauch Chunk. All the- Paleozoic formations from the bottom of the Paleozoic (2) to the last, the Carboniferous (14), are here flexed together: No. 2 being Cambrian; 3, Canadian ; 4, Trenton ; 5, Niagara ; 7, Lower Helderberg ; 8, Oriskany ; 9, Corniferous; 10, Hamilton; 11, 12, Upper Devonian; 13, Subcarbonifer- ous ; 14, Carboniferous. Fig. 1027, from H. D. Rogers, in which the flexures 1027. Section of the Coal-measures, half a mile west of Trevorton Gap, Pa. H. D. Rogers. are more gentle, is from Trevorton Gap, 45 miles west of Mauch Chunk. The whole Anthracite region has been thus upturned. Constitution of the Coal-measures. Beds of sandstone, shale, clay, and limestone, with occasional beds of coal, and a bed of fire clay commonly beneath the coal-bed, make up the Coal-measures. About one foot in 40 of the total thickness is usually good coal ; but in the Upper and Lower Productive Measures, the proportion is larger, rising to one foot in 20. The following tables, 1 A, 1 B, 2, 3, 4, derived from the reports of the recent Pennsylvania Survey (1, 2, and 3, by J. J. Stevenson, and 4, by H. M. Chance) will give a general idea of the many coal-beds in the series in western Pennsylvania, from the Upper Barren series to the Lower Productive Measures, and of their alternating beds of sandstone, shale, limestone, fire clay, and iron ore : PALEOZOIC TIME CARBONIC. 651 1. Upper Barren Series, or Permian Beds. A. DUNKARD CREEK MEASURES, GREENE COUNTY (SOUTHWESTERN COUNTY OP PA.), ABOUT 700 FEET. Beneath 80' of concealed beds including some limestone : Limestone 10', sandstone 50', limestone 4', shale 80' 144' Sandstone 30', shale 12', limestone 2', sandstone and shale 80' 124^ Nineveh coal-bed If Sandstone 100', limestone 2', biturn. shale 1', sandstone 36' 139^ DunTcard coal-bed 1|' Sandstone and shale 30', limestone 3' 33' Limestone 2 '-5', sandy shale 70', limestone 6'-15' 78'-90' Coal, local bed If Shale and iron ore 10', sandstone 31', limestone 2|', sandstone 19'-30' 62|'-73^ B. WASHINGTON GROUP, MAXIMUM THICKNESS 400 FEET. Sandstone 40', Upper Washington limestone 30' 70' Jolleytown coal-bed 1 Middle Washington limestone 15', sandstone 40' 65' Sandstone and shale 20', limestone 8', sandstone and shale 60' 88' Bituminous shale or coal-bed 1' Lower Washington limestone 20' Washington coal-bed 10' Laminated sandstone 12' Little Washington coal-bed. .. 1' Limestone 20', shale 6' 26' Waynesburg " B " coal-bed~. 1' Limestone 8', sandstone 30' 38' Waynesburg "-4" coal-bed , 2' 2. Upper Productive Coal Series or Monongahela River Series, Maximum 494 feet. Shale 0'-12', Waynesburg sandstone 70' 70'-82' Waynesburg main coal-bed 6' Sandstone and shale 60', limestone 5', sandstone 20', fire clay 3'. ... 88' Uniontown coal-bed l'-3' Sandstone and shale 60', limestone and shale 18', sandy shale 40', limestone and shale 55' 173' Sewickley coal-bed l'-6' Sandstone and shale 25', limestone 18', sandstone 10' 53' Redstone coal-bed l'-6' Shale 0'-12', Pittsburg Upper sandstone 40', limestone 10' 50'-62' Pittsburg coal-bed 5'-12' Fire clay 3' 3. Lower Barren Coal-measures (in Westmoreland County, Pa.}, 654 /ee. Limestone 6', shale 10' (underneath 3' fire clay and Pittsburg coal) 16' Coal-bed 1' Shale 10', limestone 3', shale 25' 38' Coal 1^ Shale 35', Connellsville sandstone 60' (not persistent), limestone 5' 100' Coal-bed 1' Clay 9', Morgantown sandstone 50', limestone 4' 63' 652 HISTORICAL GEOLOGY. Barton coal-bed 1' Shale 100', Crinoidal limestone 4', shale 30' 134' Coal-bed 2' Shale and sandstone 35', black limestone 4', shale 60' 99' Coal-bed l'-2' Shale 30'-50', with Mahoning sandstone (divided sometimes into Upper, Middle, and Lower), with thin layers of shale and lime- stone, and sometimes a thin coal-bed, in all 195 %' in Ligonier Valley, varying to 75' and less elsewhere 75'-195| ; 4. Lower Productive Coal-measures, or Alleghany River Series, W. Pa. Freeport Upper coal, E 2'-4' Fire clay 2'-6', shale with ore, Freeport Upper limestone, shales, sandstone ... 25'-40' Freeport Lower coal, D 2'-7' Fire clay H'-4', Freeport Lower limestone 42'-50' Kittanning Upper coal, C 1 H'~ 5 ' Fire clay 2'-4', Johnstown cement-bed, shales 2'-8' Coal 0'-2' Fire clay 0'-2', shales and slate 30'-40' Kittanning Middle coal, C 1 |'-3' Fire clay, shales, sandstone 35'-40' Kittanning Lower coal, B 3'-7' Fire clay 4'-8', sandy shales \ sometimes r 50'-60' Clarion coal, A > Clarion j l'-2' Fire clay 2 '-10', shales * sandstone I 20'-30' BrooTffoille coal, A 0'-4' Fire clay, brick clay O'-IO' POTTSVILLE CONGLOMERATE. These sections show many alternations of sandstone, limestone, and shale, with the several coal-beds, but without giving the many minor changes. Sections from the Anthracite region afford the same alternation of coal- beds with beds of sandstone (or conglomerate) and shale, but without even thin layers of limestone. But the coal-beds and the various rocks reach a much greater thickness, all being on a grander scale in this central part of the Appalachian area. The " Mammoth " coal-bed (numbered E by the 'Geological Survey) attains a maximum thickness of 50 feet; and then, above 200 to 300 feet of sandstone x (or conglomerate) and shale containing two or three thin coal seams, comes the Red Ash Bed (F), 16 to 24 feet; and above another such interval, a third great bed (Gr), 15 to 16 feet; and so on. But these thicknesses are not constant, the minimum in each of these beds in other localities (mining shafts) being half the above or less. The thickness diminishes not only westward, but rapidly also northward. At Carbondale, it is, for the whole Coal-measures, only 300 feet, and for the included coal-beds less than 20 feet. Near Wilkesbarre, the thickness is about 867 feet, with 85 feet of coal-beds, or about one foot of coal to 10 of rock. In the western Middle Anthracite field, the total at Hammond is 1512 feet, with 83 of coal-beds. Near Pottsville, in the southern field, the total PALEOZOIC TIME CARBONIC. 653 thickness is 3251 feet, and that of the 27 coal-beds, 154 feet, a ratio of 1 : 21. Of the 27 coal-beds, numbers 19 and 20 (counting from below), together 23 feet thick, but separated by 15 feet of shales in all 47 feet correspond in position to the " Mammoth " bed. The facts relating to the Anthracite region are given in detail, with magnificent maps in folio, by Ashburner, in hi& Report of the Pennsylvania Geological Survey. The Coal-measures of western Pennsylvania continue to decrease in thickness as they spread northward. Beyond Ohio, in Illinois and Indiana, a region wholly independent in its coal areas, as shown by the Ohio and Pennsylvania geologists, the Coal- measures are less than 1200 feet in thickness ; and a considerable portion of the intervening beds consists of limestone. The accompanying rocks may be of marine origin, brackish water or fresh ; and limestones with their many fossils are usually marks of marine origin. The coal-beds are not all coal. They have commonly layers of shale or shaly coal at intervals ; and sometimes so many that the bed is worthless. A bed may change in the course of a few miles to a dirt-bed, or the carbo- naceous material may wholly fail. The Pittsburg, at Pittsburg, Pa., is 10 feet thick; but it is made up of one foot, at bottom, of coal with pyritiferous shale ; 5 to 6 feet of good coal; and, above this, shale and coal, left as the roof for working, though sometimes including one or two feet of pure coal. It borders the Monongahela for a long distance, the black horizontal band being a con- spicuous object in the high shores, and in some places contains seven or eight feet of good coal. It extends into West Virginia and Ohio, over an area at least 225 miles by 100. It varies in thickness, being 12 to 16 feet in the Cumberland basin; 6 feet at Wheeling; 5 to 8 feet in Morgan, Athens, and Meigs counties, Ohio ; 5 to 6 feet at Pomeroy, where it is the " Pomeroy " bed ; 6|- to 91 feet in West Virginia, at Morgantown. But, according to I. C. White (1891), it fails nearly or wholly to the southwest of Pennsylvania, over part of West Virginia and Ohio, along a belt north-and-south in course, and 30 to 50 miles wide. Layers of clay -ironstone are often in the series, as the sections show, making parts of beds of limestone, shale, or coal, or intervening between them ; and abed of fire clay generally underlies a coal-bed. The coal chiefly of vegetable origin. The clay-bed beneath the coal, often called the underclay, generally contains fossil plants, and especially the roots or under-water stems of Lepidodendrids and Si gillarids, called Stigmarice; it is often the old dirt-bed, or the bed of earth over which the plants grew that commenced to form the coal-bed. It was either this, or the clayey bottom of the plant-bearing marshes or lakes. In some cases, trunks of trees rise from it, penetrating the coal layer and rock above it. The Nova Scotia coal region abounds in erect trunks, standing on the old "dirt-beds," as illustrated in Fig. 1028. The rock capping a coal-bed may be of any kind, for the rocks are the 654 HISTORICAL GEOLOGY. result of whatever circumstances succeeded ; but it is common to find great numbers of fragments or trunks of trees and ferns in the first stratum. The shaly beds often contain the ancient ferns, spread out between the layers with all the perfection they have in an herbarium, and so abundant that, 1028. Section of Coal-measures at the Joggins, Nova Scotia (with erect stumps and stems, a, b, c, d, in the sandstone, and rootlets in the underclays). Dawson. however thin the shale be split, it opens to view new impressions of plants. In the sandstone layers, broken trunks of trees sometimes lie scattered through the beds. Some of the logs in the Ohio Coal-measures, described by Dr. Hildreth, are 50 to 60 feet long, and three in diameter. At Carbondale, in Pennsylvania, a forest of Calamites, or tree-rushes, was cut through in opening an inclined tunnel through sandstone to the underlying coal-bed, and the trunks, or rather their fragments, were so numerous that they were used as a foundation for a tramway for transporting the coal out of the mine. In the walls crowds of other stems of the old jungle were left. Lesquereux refers the species of Calamites to C. Suckovi and (7. approxi- matus. He also states that in the roof-shale of the coal-bed at Carbondale, Pa., there was found an impression of the bark of a Lepidodendron, two feet wide and seventy-Jive feet long. Andrews mentions that thousands of the trunks of the Fern, Pecopteris arborescens Schloth., are found in the shale over the Pomeroy coal-bed; and at one place the trunk of a Sigillaria was traced by him for more than 40 feet. In Kentucky, at Paints ville, the stony bottom of the river is an irregular mosaic work made of cross-sections of trunks of Sigillaria which stand crowded together in the position of growth (Lesquereux). One trunk is 22 inches across, showing that the region was the site of a forest. Such facts are common. These facts are enough to prove the vegetable origin of coal. But Ferns, Lepidodendra, and other plant-remains are often spread out in perfection within the coal-beds, and sometimes in the solid masses of anthracite. They occur also in the textureless cannel coal, as at Breckenridge, Ky., where the coal "is marked through its whole mass by stems and leaves of Stigmaria and Lepidodendron rendered distinct by infiltration of sulphuret of iron" (Lesquereux). Further, the coal is often penetrated with the tissues and spores of the plants. Even the solid anthra- PALEOZOIC TIME CARBONIC. 655 cite has been found to contain vegetable tissues. On examining a piece partly burnt, J. W. Bailey found that it was made up of carbonized vegetable fibers. Figs. 1029, a, b are from his paper on this subject. He selected specimens which were imperfectly burnt (like Fig. 1029), and ex- amined the surface just 011 the borders of the black portion. Fig. 1029 a represents a number of ducts, thus brought to light, as they appeared when moderately magnified ; and Fig 1029 6, two of the ducts, more enlarged ; the 1029 6. 1029. Figs. 1029, a, 6, Vegetable tissues in anthracite ; 1030, Spores and part of a Sporangium, in bituminous coal'of Ohio (x TO). Figs. 1029, Bailey ; 1030, Dawson. black lines being the coal that remained after the partial burning, and the light spaces silica. The ducts were one tenth of a millimeter (about four thousandths of an inch) broad. Dawson reports like results from bituminous coal. The spores and sporangites, or spore-cases, of the Lycopods (Lepidoden- drids) and other Acrogens, abound in the coal to such an extent in some places, that it has been suggested that mineral coal was made mainly out of them. While, as Dawson has shown, this inference is not sustained by facts, such spore-cases are very common in most coal. Fig. 1030 represents, much magnified, the surface of a piece of Ohio bituminous coal, showing a fragment of a spore-case and many of the spores. The spore-cases vary in size, from a tenth to a hundredth of an inch, and in the coal they often have an amber- yellow color. Dr. Dawson states that he has a specimen of Pennsylvania anthracite full of spore-cases, but that the Pictou coal is remarkably free from them. Animal materials have also contributed to the coal, though sparingly. For animal decomposition also yields carbonaceous material ; and animal life was so abundant in the waters that the contributions in some places may have been important. The great number of fossil fishes in some very carbonaceous or bituminous shales has led to the suggestion that fish-oil may have been the sole source of the oil or gas yielded by the shales. It is not 656 HISTORICAL GEOLOGY. improbable that it was a prominent source, since the same process which will convert vegetable tissues into coal or mineral oil (page 124), will pro- duce a like result from animal oils. Equivalent coal-beds in the series. Since the coal marsh area of Pennsyl- vania, eastern Ohio, Kentucky, and West Virginia was in all probability essentially continuous, it is reasonable to look for the beds over the areas that are of equivalent age. It has been found difficult, however, to make out even the relations between those of eastern and western Pennsylvania ; that. is, of the Anthracite and Pittsburg regions. The related West Pennsylvania, and Ohio beds are more easily correlated. But any parallelism between the beds of Pennsylvania and those of Illinois and other states of the Mississippi valley, unless in the Lower Coal-measures, is improbable. Coal-measures. Full details with regard to the Bituminous Coal-measures of western Pennsylvania, West Virginia, and partly of Ohio, will be found in a Report by I. C. White, constituting Bulletin 65 of the U. S. Geological Survey. The following are facts- from eastern Pennsylvania : In the Panther Creek basin at Tamaqua, where the total thickness is 2168', the lowest coal-bed is the Lykens Valley coal, 6' thick, within the Pottsville conglomerate. 240' above- is the A coal-bed, 16'; 115' higher, the B coal-led, 9'; 235' higher the C coal-bed, 8' (with a thin bed between) ; and then, 122' above the last, the Mammoth bed, including beds D,, 12', and E, 24', and another between of 5', together with 45' and 48' of intervening rock. 211' higher comes the F, or Lower Red Ash coal-bed, 10'; 55' higher, the Bony coal-bed^ 4,'; 46' higher, the G, or Upper Red Ash coal-bed, 6'; 84' higher, the Washington coal-bed,. 3'; 92' higher, the Jock coal-bed, 7'; and then 4 coal-beds of 2' each in the next 150'; 158' higher, the First Upper Red Ash coal-bed, 4'; 106' higher, the Second Upper Red Ash coal-bed, 3'; 63' higher, the Third Upper Red Ash coal-bed, 1'. From the Mammoth to the Lykens valley coal-bed the coals are of the White Ash group ; the remainder are divided into the Upper and Lower Red Ash groups, along a plane below the third coal-bed from the top. In the Pottsville basin, between the Mammoth and Lykens Valley coal-beds, there are 7 coal-beds ; and one, 660' above the Lykens, called the Buck Mountain coal-bed, is 8' thick. The Wilkesbarre section gives widely different results. In western Pennsylvania, the Coal-measures have their greatest thickness at the West Virginia line, midway in Greene County, Pa. ; and from this point there is a thinning westward to about one third. Passing into Ohio, the interval between the Pittsburg and Uniontown coal decreases north- ward from 200' to 60' or less (Stevenson). The Pottsville conglomerate in Mercer County, Pa., afforded I. C. White (Pa. Rep. Q, 3, 1880) the following section : Homewood sandstone 50', shales 5', iron ore 2', limestone 2|' 59^' Coal, Upper Mercer , 2%' Shales 25', iron ore 2', Lower limestone 2|', shales 10' 39' Coal, Lower Mercer 2%' Shale 10', iron ore 1', shales with Upper Connoquenessing sandstone.. 66' Coal, Quakertown 2' Shales, Lower Connoquenessing sandstone 30', Sharon shales 30' 100' Coal, Sharon 4' Fire clay and shale 5', Sharon conglomerate 20' 25' The thickness of the Coal-measures in Ohio is about 1250': the Lower Productive 250', with 7 coal-beds ; the Lower Barren, having the Mahoning sandstone at its base, 500'; PALEOZOIC TIME CARBONIC. 657 Upper Productive, 200'; Upper Barren, 500', but much reduced from the original thickness by denudation ; the total number of coal-beds is 13 ; the mean thickness of the lower 7 is 4i'; of the upper 6, 4'. Bed No. 1, called the Brier Hill, Massillon, or Jackson coal, is 3' to 6' thick, and is supposed to be No. A of the Pittsburg section ; No. 6, the Upper Freeport, 3' to 12' thick ; No. 8, 4' to 8' thick, the Pittsburg coal-bed, at the top of the Lower Barren Measures ; and No. 11, 1|' to 4' thick, the Waynesburg coal-bed (Newberry). In Indiana, the Coal-measures cover an area of about 7000 square miles over the western part of the state, are 800' to 1000' thick, and include 10 coal-beds varying from 1' to 11' in thickness (Collett). In Illinois, the total thickness is 600' to 1000', and the number of workable coal-beds 6, and of other thin seams, 6. The thickness of the former is nearly 20' (Worthen). Near Morris, and elsewhere, in northeastern Illinois, there is a single bed of coal with clay &bove and below. Four miles to the southeast of Morris, sandy shales of the Coal-measures contain concretions which have made the place famous because of the many kinds of Ferns, Insects, Spiders, Myriapods, rare Crustaceans, and even Amphibians, which have been found in the concretions the specimens having been in many cases the nuclei. No marine fauna has been found in them. In southwestern Kentucky, the Coal-measures north of Pine Mountain are 1650' thick, and contain 9 workable beds of coal ; and farther east they are still thicker. The Coal-measures spread northwestward over southwestern Iowa, where they have a maximum thickness of 600', and a thickness of coal-beds of about 8', as in Illinois. The Coal-measures extend northward beyond the limits of the upper beds of the Subcarbonif- erous limestone. At Davenport, on the Mississippi, a boring found a thickness of 30', and the beds resting on the Devonian Corniferous limestone. In Arkansas, the area of the Coal-measures is about 1000 square miles, and the mean thickness of the coal-beds is estimated at 3'. The isolated coal area of Michigan covers about 6700 square miles, and the beds have a thickness of 300' or less. At East Saginaw, this 300' includes the underlying Parma white sandstone 105', and the overlying Woodville brown sandstone 79 feet ; and in the intermediate shales and sandstone there is one bed of coal 3' to 4' thick (Winchell). In Alabama, the Coal-measures cover 5500 square miles. There are 3 areas, the Warrior, the Cahaba, and the Coosa. The first contains nine tenths of the whole area. The thickness near Tuscaloosa, where the beds disappear beneath more recent formations, is about 3000'. The number of coal seams is about 35, of which 15 are over 2' thick, and 6, of 4' and over. The beds become thinner to the northwest. The lowest of the coal-beds are those in the Pottsville conglomerate. The Rhode Island Carboniferous covers the most of the southern part of the state, and extends northward, through Providence, to the northern border: there it passes into Norfolk County, Mass., and thence eastward, through Bristol County, to Plymouth County. The exact limits, east, west, and north, have not been made out, the stratifica- tion of the rocks being much obscured by displacements or flexures and metamorphism. There are conglomerates and slates which are supposed by Hitchcock and Jackson to be a part of the formation. The quartzose conglomerate outcrops at Newport and elsewhere, and forms a bold feature in the landscape at " Purgatory," 2 miles east of Newport, and at the "Hanging Rocks." The stones vary in size from an inch to a foot or more. Associated with the slate there are beds of limestone. The principal points where coal outcrops are near Providence, Cranston, Bristol, Portsmouth, Valley Falls, Cumberland, and Newport (a thin bed outcropping on the coast) , in Rhode Island ; and in Raynham, Wrentham, Foxboro, and Mansfield, in Massachu- setts. The beds are much broken and very irregular in thickness, owing to the upturning and flexures the formation has experienced, and the coal is an exceedingly hard anthra- cite, because of the metamorphism, and to some extent is graphitic. Still, the slates often contain fossil plants, part of which are identical in species with those of Pennsylvania. DANA'S MANUAL 42 658 HISTORICAL GEOLOGY. Near Portsmouth, at Aquidneck, three beds are reported to exist, 2' to 20' thick, and at Case's, one of the three is 13' thick ; at Providence, one, of 10'; at Valley Falls, five, 6' to 9'; at Cumberland, two, 15' to 23'; near Mansfield, several, with the maximum thickness 10'. The earliest opening was made at Case's, near Portsmouth, in 1808. At Worcester, Mass. , an independent coal area, there are mica schists and graphitic slate, with remains of a species of Lepidodendron. Cape Breton, Nova Scotia, New Brunswick. A large part of Cape Breton and the northern half of Nova Scotia, and more than two thirds of New Brunswick, are covered by the coal formation. The chief of the coal mines are in Nova Scotia, in the Pictou, Colchester, and Cumberland districts. In New Brunswick, the formation is thin and yields little coal. At the Joggins, in the Cumberland district, the beds, according to Dawson, rest on 3000' of Subcarbonif erous beds, have a thickness of 13,000', and are made up of sandstone, conglomerates, shales, and impure limestone. Of the whole, 5000' to 6000' pertain to the conglomerate or Millstone grit, 4000' to the Lower Coal-measures, and 3000' to the Upper, a large portion of which is regarded by Dawson, on account of the fossils, as Permian. In the series, there are 76 dirt-beds and coal-seams, indicating as many levels of verdant fields or marshes. Each dirt-bed is a clayey layer with stumps of StigmarisB and other plant remains ; but only 15 contain any coal. The main coal-bed at the Joggins is only 5' thick, with a foot or so of clay along the middle. The Permian at Pictou has a thickness, according to Fletcher, of 1146', but on John River, near the boundary of the Colchester district, 8107'. For a detailed report on the Pictou and Colchester districts, by Fletcher, see Can. Geol. Rep. for 1890-91. The Millstone-grit portion includes thick beds of coarse gray sandstones, containing prostrate trunks of Coniferous trees in its upper and middle parts, with red and com- paratively soft beds in its lower ; many layers of coaly shale occur throughout, but no coal-beds. At Pictou, where the beds dip 20 or more, the mean thickness of the main coal-bed is 38'; of another, 159' below, 15' ; and 280' below this occurs the McGregor seam 12' thick. The total thickness of the Carbonifererous is about the same as at the Joggins (Dawson). A Carboniferous formation without coal is the great fact for the western half of the continent. Beyond the Mississippi, near the meridians of 97 to 101 W., the formation, as it extends westward, becomes increasingly thinner in its coal-beds and passes beneath the Triassic, Cretaceous, and Tertiary beds of the eastern Rocky Mountain slope. The formation makes its first reappearance at the surface at about 104 W., in the Black Hills of Dakota ; but it comes up destitute of coal, and is a limestone formation 400' thick, including a middle portion of sandstone, 75' thick. Moreover, through the region of the Rocky Mountains farther west, and also northward through British America, wherever the Carboniferous is to be seen, the rock is a barren limestone, or limestone and sandstone. It is widely distributed as a surface rock at the base of Archaean ridges and elsewhere, has its largest continuous area in Arizona, is widely distributed over the Great Basin in Nevada, occurs also in Utah and Montana, whence it extends northward beyond the United States boundary along the summit region of the mountains. The deposition of Mesozoic, Cenozoic, and lacustrine beds, and the extensive ejection of igneous rocks over the vast region of the United States, between the meridian of 105 W. and the Pacific, have left little of the Paleozoic formations in sight. Along the summit region the beds rest on Silurian or Cambrian beds. The Carboniferous is the surface rock at the Grand Canon of the Colorado. It there comprises the Aubrey limestone, as the summit portion of the lofty walls, 835' thick ; below this, the Aubrey sandstone, often having cross-bedded layers for 1455'; and then the " Red- wall " limestone, having a thickness of 970' ( Walcott), in all 3260'. The lime- stones are more or less cherty and in part shaly or arenaceous, and the upper contains some gypsum. A portion of the lower limestone, of undetermined thickness, contains Subcarbonif erous fossils. PALEOZOIC TIME CARBONIC. 659 In the Wasatch, the Carboniferous beds are about 13,000' thick, the Upper Coal- measure limestone 2000' thick ; below this is the Weber quartzyte, 6000'; and then 5000' of the Wasatch limestone, the lower part of which contains Subcarbonif erous fossils. The Carboniferous formation in the Eureka basin, Nevada, has a total thickness not far from 10,000', of which the Weber conglomerate comprises 2000', and a quartzyte at the base, 3000'. The upper member is only 500' thick, but has a thickness of 2000' to the north- west. (Hague.) In California, Carboniferous beds, consisting partly of limestone, occur in the Sierra Nevada along a broad belt west of, and nearly parallel to, its axis. They extend inter- ruptedly, says Whitney (1866), from Shasta County, near Pitt River (40 45' N. where limestone of the period was first identified by Trask in 1855) through Plumas County, southwestward, to the Tahichipi valley, more than 500 miles. The limestone occurs at intervals interstratified with the argillyte, mica schist, and siliceous slates of the auriferous series, and disappears at times, as Whitney states, by graduating into calcareous sand- stones and the siliceous slate. The fossils obtained by Trask near Bass Ranch, comprising species of Fusulina (Fig. 1069), a Lithostrotion hardly distinguishable from L. mammillare, and other kinds, were referred by Meek, with much expressed doubt, to the Subcarbo- nif erous; and Gabb suggested the same conclusion for the fossils of the limestone at Pence's Ranch, 80 miles to the southeastward. H. W. Turner reports Fusulina from Kite's Cove, Mariposa County, and, from other parts of the same interrupted limestone belt, in Calaveras and Amador counties, and at different points in Plumas County. It is probable that the rocks are partly at least of the Carboniferous period. Carboniferous rocks occur also in the Klamath Mountains and Coast Range, according to Fairbanks and Diller. But they have not yet been identified in Oregon and Washington. They exist in British Columbia, in some parts of the Coast region, and are extensively distributed over the interior plateau, extending northward as far at least as the Peace River region, in latitude 55-56 N. In the Arctic regions, Carboniferous beds are reported from Melville Island, at Cape Dundas, Bridgeport Inlet and Skene Bay ; Baring Island at Cape Hamilton ; Byam Martin Island ; and on Bathurst at Schomberg Point and Graham Moore Bay. The line of outcrops of the beds runs E.N.E. They are accompanied by clay ironstone in nodules, as is usual in coal regions (Haughtoii). For notes on the Carboniferous areas of the Arctic regions, see, further, G. M. Dawson, Hep. Geol. Canada, for 1886. In Mexico, Carboniferous limestone, representing the Carboniferous period, or the Carboniferous and Permian periods, has been observed in some of the ridges and mountains of Coahuila and Nuevo Leon (Frazer and Hall), and also on the borders of Mexico and Guatemala ; also, in Nicaragua, with overlying Permian and underlying Silurian and Devonian (Crawford, 1890). In South America, the Carboniferous beds have great extent in Brazil, in the Amazon valley, as great as the North American Carboniferous, but they afford no coal (Derby, Am. Jour. Sc., xvii., 1879). The following probable correlations are based by Lesquereux on the distribution of the species of coal-plants : Coal A, which exists within the Pottsville conglomerate, or Millstone grit, at the basis of the Coal-measures, or its equivalent plant- bearing beds : at Shamokin, Lehigh Summit, lower bed at Trevorton, Broad Top, in Pennsylvania ; at Massillon, Ohio ; at Union Mines, in Crittenden County, Kentucky. Coal B, Archbald, Pa. ; Spring Creek, Ind. ; Union, Greenup, and Carter counties, Ky. ; Murphysboro, Mazon Creek, Morris, 111., in shale over coal. Coal B or C, Carbondale, Pa. ; Cannelton, Pa. ; Clinton, Mo. Coal C, Archbald, Shamokin, Pittston, at Boston mine, etc. ; Eugene, Vermilion County, Ind. 660 HISTORICAL GEOLOGY. Coal D, Carbon Hill, Pittston, Pa. ; Vermilion County, Ind. ; Duquoin and St. John, 111. Coal D or E, Sullivan County, Ind. ; Hopkins and Christian counties, Ky. Coal E, Mammoth bed at Pottsville, Pittston, Yatesville, Pa. ; Nelsonville and Cosh- octon, Ohio ; Stark and Peoria counties, 111. Coal E and F, Wilkesbarre, Pa. ; Nelsonville and Coshocton, Ohio. Coal F, Plymouth, Pittston, and Maltby, Pa. Coal G, Olyphant, Plainsville, Gate and Salem veins, Pottsville, Pa. ; Pomeroy, Ohio. At Cannelton, Pa., the number of species of plants obtained from the coal-bed of the B or C horizon, according to Lesquereux, is 140 ; at Mazon Creek, 111., from the bottom of the coal-bed B, 150 species, and adding those from the overlying clay-bed, 200 species ; and if the species from the same bed at Murphysboro be added, with others the bed affords in Missouri, the number mounts up to 250 species, which is a very large flora for one coal-bed level. The whole number of plants thus far described from the American Coal-measures, the Permian portion included, is 900. 3. PERMIAN PERIOD. ROCKS KINDS AND DISTRIBUTION. It has been stated that the Upper Barren Measures of Pennsylvania and West Virginia, having a thickness in Monongalia* County of 1044 feet, were of the age of the Permian period, though continuous in bedding with the strata below. Similarly, the upper beds clayey beds, sandstones, with some impure limestones in the Coal-measures of Kansas, Missouri, Illinois, Nebraska, and Texas, are referred to the Permian. The same is true for an upper part of the Coal-measures of Nova Scotia, New Brunswick, and Prince Edward Island. The evidence of Permian age consists in the presence of remains of plants, Mollusks and Vertebrates, like those of the foreign Permian. Permian beds have also been identified in the region of the Colorado Canon in Arizona and Utah, where 845 feet of limestone and shales containing gypsum, overlying Carboniferous limestone, are referred to this period. In the Wasatch, the beds have a thickness of 600 feet. Permian beds were identified in the San Francisco Mountains by Marcou in 1853 ; and in the Guadalupe Mountains, New Mexico (a white limestone), by B. F. Shumard in 1858. About the Colorado Canon they have been studied by Walcott (in 1880) and others. The rock in the Wasatch is the " Bellerophon limestone " described by King (1878). Permian was identified in Nova Scotia by Dawson in 1845 ; in Kansas, by Meek, Swallow and Hawn, in 1858 ; in Illinois, by Worthen, in 1858 ; and soon after in Missouri and Nebraska by Meek ; in Pennsylvania and West Virginia, by Fontaine and I. C. White, in 1880. Cope's observations in Illinois and Texas were made in 1875, and later; C. A. White's, in Texas, in 1889. On the Kansas Permian, see, further, Prosser's paper of 1894. The Texas Permian occupies the western portion of the Carboniferous area. North of the Brazos River the lower beds, in the Wichita^of Cummins, are red clays and sand- stones, with some impure limestone at top. The fossils described by C. A. White are from this part of the series, and so also the Vertebrates described by Cope. Above are the so-called Clear-Fork and Double Mountain division, and then come the Dockum beds, different in rocks and fossils, which are referred to the Triassic. PALEOZOIC TIME CARBONIC. 661 ECONOMICAL PRODUCTS. Coals, Iron Ores, Clays, and Salt of the Carboniferous and Subcarboniferous Formations. 1. Coal. Coal occurs of three kinds: (1) Anthracite, or stone coal; (2) ordinary Bituminous, sometimes distinguished as " cubical coal," in view of its natural fracture ; and (3) Cannel coal, the dull textureless bituminous coal, breaking irregularly, with a conchoidal fracture, and only occasionally con- stituting parts of coal-beds. Excepting the cannel, the coals have distinctly, on a cross-fracture, a faint banding, due to a straticulate structure or bedding, and are rarely laminated unless very impure. The blocks into which bitumi- nous coals break have probably been made by the strains to which the coal- bed had been subjected ; they are not those of crystallization. The bituminous coals which soften in the fire and cake over are called caking or cementing coal ; and those which burn without caking, the open- burning coals. The " Block coal " of Ohio, Indiana, and the neighboring states, is of the non-caking kind, that most convenient for furnaces and open fires. The caking coals are prepared for metallurgical purposes by conversion into coke by partial combustion under cover (in ovens), which drives off the volatile matter. In the best process there is a loss usually of 20 to 35 per cent of weight, and an increase in bulk and hardness. At the same time the coal loses about half its sulphur. The first of the following tables gives the results of analyses of coals, and also of peat, showing the amount of the several constituents ; and the second, the amount of fixed carbon, and of volatile hydrocarbons (gas, oil) afforded, and besides, the water and ash, or impurities. The flame given out in a fire is that of the burning gas as it escapes. This gas is almost wholly a compound of carbon and hydrogen, or a hydro- carbon ; but it includes a little carbonic oxide (carbon monoxide), which has a bluish flame ; and in the case of anthracites, which have very little volatile matter apart from the moisture, this gas is the chief one. But anthracites shade down into the semi-bituminous, and the flame varies consequently from bluish to yellow. Cannel coal (called in Scotland Parrot coal) affords usually the most volatile hydrocarbons, and is valuable for gas making ; and it will be much used for its yield of mineral oil or petroleum whenever the oil-wells give out. It occurs in Ohio and Indiana, and still more abundantly in eastern Ken- tucky, where Breckenridge is a noted locality. The amount of impurity in them is often large, and the beds frequently contain remains of Fishes, Crustaceans, and some other fossils, which is not true of the ordinary bitumi- nous coal. The fossils appear to be almost solely those of fresh waters. Linton, Ohio, is a locality famous for its Fishes and Amphibians, its cannel coal affording 50 species or more. The Subcarboniferous beds of New Brunswick, in some parts of King's, Albert, and Westmoreland counties, afford a semi-asphaltic material called 662 HISTORICAL GEOLOGY. albertite, looking like bitumen or asphalt, but not readily fusing like it in a candle. It occupies rents in the rock, instead of constituting layers. A similar substance, called grahamite, occurs under similar conditions in the Coal-measures of West Virginia, 20 miles south of Parkersburg. It is partly columnar in fracture at right angles to the walls of the vein. Both are sup- posed to have been made from the oxidation of mineral oil. 1 Anthracite, Pennsylvania Carbon 90-45 Hydr. 2-43 Ox. 2-45 Nitr. Sulph. Ash 4-67, Analysts Regnault. 2 Anthracite, Pennsylvania 92-59 2-63 1-61 0-92 2-25, Percy. Anthracite South Wales 92-56 3-33 2-53 1-58, Regnault* 4 Caking Coal Kentucky 74-45 4-93 13-08 1-03 0-91 5-00 Peters 5. 6 Caking Coal, Nelsonville, Ohio . . Caking Coal, South Wales.. 73-80 82-56 5-79 5-36 16-58 8-22 1-52 1-65 0-41 0-75 1-90, 1-46, Wormley. Noad. 7. 8 Caking Coal, Northumberland . . Non-caking, Kentucky 78-69 77-89 6-00 5-42 10-07 12-57 2-37 1-82 1-51 3-00 1-36, 2-00, Tookey. Peters. 9. 10. 11. 1?, Non-caking, "Block Coal," Ind. Non-caking, Brier Hill, Ohio. . . . Non-caking, S. Staffordshire .... Non-caking Scotland 82-70 78-94 76-40 76-08 4-77 5-92 4-62 5-31 9-39 11-50 17-43 13-33 1-62 1-58 2-09 0-45 0-56 0-55 1-23 1-07, 1-45, 1-55, 1-96, Cox. Wormley. Dick. Rowney. 13 Cannel Coal, Breckenridge . . 68-13 6-49 5-83 2-27 2-48 12-30 Peters. 14 Cannel Coal Wigan 80-07 5-53 8-10 2-12 1-50 2-70 V~aux 15. 1f> Cannel Coal, " Torbanite " Bituminous Coal, Wyoming . . . 64-02 73-55 8-90 4-17 5-66 17-20 0-55 1-93 0-50 1-18 20-32, 1-86, Anderson. 17, Bituminous Coal, Wyoming. 75-20 4-74 10-37 1-37 I'll 7-20, 18 Albertite Nova Scotia 86-04 8-96 1-97 2-93 0-10 Wetherell 19 Brown Coal, Bovey 66-31 5-63 22-86 0-57 2-36 2-27, Vaux. flO Brown Coal, Wittenberg ... 64-07 5-03 27-55 3-35, Baer. 21. Peat, light brown (imperfect). . . Peat, dark brown 50-86 59-47 5-80 6-52 42-57 31-51 0-77 2-51 Websky. Websky. 7!3 Peat, black 59-70 5-70 33 O4 1-56 Websky. 24. Peat, black.. 59-71 5-27 32-07 2-59 Webskv. No. 13, the Breckenridge cannel, of Hancock County, Ky., consists, when the ash is excluded, of carbon 82-36, hydrogen 7-84, oxygen 7-05, nitrogen 2-75 ; and the Bog-head cannel of Scotland, called also torbanite, contains carbon 80-39, hydrogen 11-19, oxygen 7-11, nitrogen and sulphur 1-31. The "Mineral charcoal " differs little in composition from ordinary bituminous coal ; there is less hydrogen and oxygen. Rowney obtained, for that of Glasgow and Fifeshire, carbon 82-97, 74-71, hydrogen 3-34, 2-74, oxygen 7-59, 7-67, ash 6-08, 14-86. The nitrogen is included with the oxygen ; it amounted to 0-75 per cent in the Glasgow charcoal. Exclusive of the ash, the composition is, carbon 88-36, 87-78, hydrogen 3-56, 3-21, oxygen and nitrogen 7-28, 9-01. The oxygen in a coal, which, as the table shows, varies from about 10 pounds to 15 in a hundred in the ordinary bituminous coals, is so much waste material as far as the heating purposes of the coal are concerned, because the atmosphere is at hand to supply all that combustion requires. The moisture also causes loss of heat, because of the amount required to evaporate and expel it. The following are other analyses of anthracite and bituminous coal ; they are a few from the many by McCreath, of the Pennsylvania Geological Survey. The amount of volatile hydrocarbons is given in the second column. PALEOZOIC TIME CARBONIC. 663 8p.gr. Anthracite, Mammoth 1-617 1-631 1-575 Bituminous, Waynesburg Pittsburg. Freeport Upper, Kittanning Upper , Vol. Fixed Carbon Sulphur Water Ash 3-08 86-38 0-50 4-12 5-92 4-27 83-81 0-64 3-09 8-18 4-38 83-27 0-73 3-42 8-20 38-30 48-97 2-73 1-04 8-97 34-68 49-59 1-27 1-27 13-19 37-74 54-56 1-50 1-73 4-47 25-20 65-52 2-25 1-27 5-76 37-22 56-01 0-98 1-04 4-15 29-68 63-77 1-72 0-70 4-13 25-77 70-22 0-62 0-80 2-59 23-91 64-53 4-79 0-77 6-00 39-22 55-69 0-57 2-71 1-81 It is found that the Pittsburg coal affords 0*0011 to 0-1248 per cent of phosphorus, which becomes 0-0018 to 0-2003 in the coke. Other analyses are given in the Geological Reports of Ohio, Kentucky, Indiana, Illinois, etc. It is useless to cite further from them, since the variation is very large in a single bed as it is traced over the country, and the state reports should be referred to for details. The Arctic coal, of Grinnell Land (81 43' N. and 64 4' W.), is good caking bituminous coal ; it afforded R. J. Moss, on analysis, carbon 75-49, hydrogen 5-60, oxygen and nitrogen 9-89, sulphur 0-52, ash 6-49, water 2-01 = 100 (Proc. R. Dublin Soc., 1878). The ordinary impurities of coal, making up its ash, are silica, a little pot- ash and soda, and sometimes alumina, with often oxide of iron, derived usually from sulphide of iron (pyrite or marcasite), besides, in the less pure kinds, more or less clay or shale. The amount of ash in the selected coal does not ordinarily exceed 10 per cent, but it is sometimes 30 per cent ; and rarely it is less than 2 per cent. Thin layers of pyrite are rather common, and occasionally a bed of other ores of iron is intercalated. Wormley gives the following analyses (besides others) of the ash of two coals, one from the Youghiogheny, in western Pennsylvania, and the second from Pigeon Creek, Jackson County, Ohio : Silica 49-10, 37-40, alumina 38-60, 40-77, sesquioxide of iron 3-68, 9-73, magnesia 0-16, 1-60, lime 4-53, 6-27, potash and soda 1-10, 1-29, phosphoric acid 2-23, 0-51, sulphuric acid 0-07, 1-99, sulphur (combined) 0-14, 0-08, chlorine race=99-61, 99-64. The fact that there is too much sulphur in the Ohio coals for combination with the iron present is shown in the following table, containing some of his results : Sulphur in the coals 0-57 1-18 2-00 0-91 0-86 Iron in the coals 0-075 0-742 0-425 0-122 0.052 Sulphur required by the iron. .. 0-086 0-848 0-486 0-139 0-06 The source of the impurities is in part the vegetation of which the coal was made, which is shown on page 74 to be sometimes large, even as regards silica and alumina, the constituents of a clay, and large also for calcium carbonate and potash. According to the average composition of Lycopods, the dried plant affords 5 pounds of ash to 100 of the plant, and 40 per cent of this is alumina and silica (27 alumina and 13 silica) , and hence these two ingredients make up 2 per cent of the plants. Ferns, with the same amount of ash, afford, as the average, 27 per cent of silica, with no alumina. Equiseta afford, on an average, 20 per cent of ash, and 50 per cent of this may be silica. 664 HISTORICAL GEOLOGY. Supposing, now, that Lycopods (Lepidodendrids, etc.) afforded one half the material of the coal-beds, and the other plants the rest, and that the silica and alumina of the former averaged 40 per cent, and of the latter only 27 per cent, this being all silica, then the amount of these ingredients afforded by the vegetation would be 1 -66 per cent of the whole weight when dried. This would make the amount of silica and alumina, in the bituminous coal made from such plants (supposing three fifths of the material of the wood lost in making the coal, as estimated on page 713), 4 per cent ; and the whole amount of ash about 4-75 per cent. At the same time, the ratio of silica to alumina would be nearly 3 to 2, Now many analyses of bituminous coal have obtained not over 3 per cent of ash, or impurity, although the general average, excluding obviously impure kinds, reaches 4-5 to 6 per cent ; being, for the coals of the northern half of Ohio, 5-12, and for the southern half, 4-72. It hence follows that (1) the whole of the impurity in the best coals may have been derived from the plants ; (2) the amount of ash in the plants was less than the average in modern species of the same tribes ; (3) the winds and waters for long periods contributed almost no dust or detritus to the marshes ; and (4) the ash, or else the detritus, was greatest in amount toward the borders of each marsh-region. In that era of moist climate and universal forests, there was almost no chance for the winds to gather dust or sand for transportation. In rare cases, an occasional bowlder or rounded stone has been found in a coal-bed, as well as in other layers of the Coal-measures. E. B. Andrews describes one of quartzyte, lying half buried in the top of the Nelsonville coal-bed, at Zaleski, Ohio, which was 12 and 17 inches in its two diameters. F. H. Bradley reports one, also of quartzyte, about four by six inches, found in the middle of the coal-bed mined at Coal Creek, E:ist Tennessee. These may have been dropped from the roots of floating trees, as has happened to masses of basaltic rocks occasionally found upon the coral atolls of the Pacific. Sulphur also occurs, in some coal-beds, as a constituent of a resinous sub- stance ; and Wormley suggested that part of the sulphur in the Ohio coals is in some analogous state. The mineral oil and gas of western Pennsylvania come wholly, or nearly so, from Chemung beds of the Devonian not from the Carboniferous (page 606). 2. Iron Ores. The ore-bearing layers of the Subcarboniferous and Carbon- iferous series occur in connection usually with the beds either of limestone or of shale, but sometimes with the sandstone and coal-beds. As these ores are more or less impure from mixture with clay, they are called day-ironstone. The limestones often contain iron carbonate (siderite) a gray ore, stone-like in aspect, of specific gravity 3-7 to 3-8. It occurs either in solid beds, from a few inches to two or three feet in thickness, or in nodules, or " ball ore," more or less united into a layer. The same limestone often contains also nodules of another valuable ore, limonite (page 71), the ore which affords a brownish yellow powder, though often brownish black to black in outside color. This limonite has frequently been made by the oxidation of the siderite. The Ferriferous limestone, just below the Kittanning coal-bed, con- tains both of the ores mentioned. The limonite in nodules, or as a " ball PALEOZOIC TIME CARBONIC. 665 ore," is common also in beds of shale, in layers of a few inches to a foot or more in thickness, and sometimes forms beds beneath the fire clay that underlies a coal-bed. Another kind of clay-ironstone is hematite or iron- sesquioxide, looking usually as stone-like as the preceding, but distinguished by its affording a red powder. These ore-masses are often siliceous, from disseminated silica, and therefore very hard. These ores, but especially the first two, are a very important source of iron in coal regions. The nodules are of concretionary origin ; that is, were made by the concreting together of iron oxide from iron-bearing salts carried down into marshes, and are not transported stones rounded by friction. 3. Clay-beds. Abed of fire clay has been mentioned as usually underlying a coal-bed. The clay varies in purity on one side down to sandy clay, or to carbonaceous shales, and on the other to the purest of white clays, valuable for making pottery, fire-brick, and tile (see page 81). The thickness of the beds varies from a few inches to sometimes half a dozen feet. They are apt to be more or less discolored by iron-oxide, so as to make cream-colored instead of white pottery ; and sometimes the bed overlies a bed of iron ore, .-and is pure white only at top. The very common presence of pure white clays in the Coal-measures is a consequence of the production of carbonic acid, and also of organic acids, by :the vegetable decomposition that goes on indefinitely in the plant beds. The sediments, whether of sand or mud, contain more or less feldspar; and the action of these acids on the feldspar removes the alkali and produces the clay (page 129) . The clay so made will be at first colored by iron oxide, if .any iron-bearing mineral is present (the common fact); but the vegetable decomposition going forward results in partly deoxidizing the iron oxide (reducing it to FeO); and then the iron in this state is taken up by the acids and carried off in solution (page 124) until the blanching in many cases is complete through part or all of a thick bed. The abundance of carbonic acid, set free under the conditions described, accounts also for the very frequent occurrence of iron-carbonate (or siderite) mentioned above. The presence of potash or soda in the clay is probable evidence of the presence of undecomposed feldspar, and of over 7 per cent of it to 1 per cent of the alkali a point of geological as well as economical interest; for such clays are fusible and not properly fire clays, and therefore are not suitable for fire brick. The presence also of lime and iron gives the clays fusibility. On Ohio clays, see Ohio G. Rep., v., 656. 4. Salt. Saline waters have been obtained in many regions from borings down to the Carboniferous strata, but usually they are only saline enough to be spoilt water. In Michigan, strong brines are supplied from the Sub- carboniferous beds, and they are used for the manufacture of salt in the Saginaw valley. The same beds contain extensive deposits of gypsum. In Ohio, productive brines come partly from the same horizon. Those of Kanawha in West Virginia are from the lower part of the Coal-measures; and Kansas beds of the same period have been found to afford brines. 666 HISTORICAL GEOLOGY. LIFE OF THE CARBONIFEROUS PERIOD. PLANTS. Forests and jungles made of Cryptogams of the tribes of Fernsv Equiseta, and Lycopods, along with Gymnosperms related to the Cycads and Yews, and covering interminable marshy plains and fields, were the striking 1031. Carboniferous vegetation. Russell Smith. feature of the coal era. Though desolated again and again, either universally or partially, by the returning waters, and over the large submerged areas kept desolate for many centuries or series of centuries again and again, the ver- dure in all its luxuriance spread over the emerging land, with little change in the foliage, for other times of luxuriant growth and of peat-making. Only toward the close of the era, when the Permian period was commencing, had the forests lost the larger part of their great trees of the tribe of Lycopods. Unlike the present world, there were no Angiosperms and no Palms. It is not positively known that there were Endogens of any kind. There was certainly no grass over the fields, the most common of Endogens. With Angiosperms and Endogens absent, there were no conspicuous flowers, no beautiful foliage except that of the Ferns and fern-like trees, and no fruit PALEOZOIC TIME CARBONIC. 667 and no fragrance but that of Conifers and Cycads. Even Mosses, so common in modern swamps, and the chief source of modern peat, have left no evi- dence of their presence. A general idea of the vegetation and scenery of the era during its periods of verdure may be gathered from the accompanying ideal sketch (Fig. 1031), from a painting 1 by Russell Smith. The tree to the left of the center, and others with similar palm-like tops, are the Tree-ferns ; and smaller Ferns make up much of the foreground. The other trees are Lycopods, the Lepi- dodendrids ; and one bare trunk to the right is that of 1032 ' a Sigillaria. Other straight stems with leaves (or branch- lets) at regular intervals are the Equiseta or Calamites. The Cycad-like Cordaites, with their long strap-like leaves, with probably others having almost the foliage of a Fern-tree, should have been in the view ; for they added largely, as Lesquereux and others have stated, to the forest trees. But of other Grymnosperms, the so-called Conifers, there are few indi- cations in the beds. They may have been common over the drier fields and hills. Forests made of the Equi- seta and Lycopods of to-day would hardly overtop a man's head. TheyVould be simply shrubbery of "Horse-tails" and "Ground Pines." The height of the largest modern Lycopod is five to six feet ; that of the ancient, 60 to 90 feet. In habit and in foliage they were much like the Spruces and Pines of the present day, the length of the leaves varying greatly, as illus- trated in Fig. 1032. The Equiseta of the present time are slender, herbaceous plants, with hollow stems ; while the Calamites of the Carbonifer- ous marshes included species having partly woody trunks, a diameter of 3 to 10 inches, and a height of 30 or 40 feet. Ferns now grow into trees in tropi- cal and warm temperate climates, but only small trees, and poor in wood compared with some in the coal era. While the terrestrial vegetation was thus abundant, seaweeds after the old style were still in the waters. The Spirophyton caudagalli of the Lower Extremity of a branch of Lepidodendron, with the leaves attached. 668 HISTORICAL GEOLOGY. Devonian, or a related species, is common in some portions of the Pottsville conglomerate in Kentucky and elsewhere. 1. Vascular Cryptogams. Lycopods. The Lepidodendron trees had the exterior embossed with oblong scars, as in Figs. 1033, 1034, and 1036. 1033. 1035. Fig. 1033, Lepidodendron aculeatum ; 1034, Lepidodendron clypeatum ; 1035, Halonia pulchella. Fig. 1033, Fair- child ; 1034, 1035, Lesquereux. Leaves like those of the Spruce or Pine occasionally occur on the fossil stems (Fig. 1040); and in some foreign specimens of L. Sternbergii Brgt., from Aus- trian coal-beds, they are over a foot long, and as closely crowded on the branches as in any modern pine. The Lycopodium dendroideum of modern forests, if magnified largely, would give a good idea of the aspect of the 1036. 1036-1038. 1037. o Fig. 1036, Lepidodendron Veltheimanum ; 103T, Sigillaria SiUimani ; 1038, S. Pittstonana. Lesquereux. trees. The cones of Lepidodendrids were long, and much like those of a living Lycopod, and are referred to under the name Lepidostrobus, and the leaves of the cone under that of Lepidophyllum. The stems, called Lycopo PALEOZOIC TIME C A KBONIC. 669 dites, are slender, small-leaved, and much like those of Lycopodium dendroi- deum, though often large. The Halonia, Fig. 1035, is a decorticated stem or rootlet of uncertain relations. Two species of Sigillaria are represented in Figs. 1037, 1038. The figures show that the scars are peculiar in having at the center a dot, and a short convex line either side ; the exterior of the stem is generally vertically banded or costate, as in the figures. 1039-1044. 1039. 1040. 1042. 1044. 1041. LYCOPODS. Fig. 1039, Lepidostrobus hastatus (or cone of a Lepidodendron) ; 1040, Lepidodendron lanceola- tum, Lx. ; 1041, Stigmaria. SCARS OF TREE-FERNS. Fig. 1042, Stemmatopteris punctata (x) ; 1043, Mega- phyton McLayi ; 1044, Cyathea compta. Figs. 1039-1043, Lesquereux ; except 1041, Dawson. In both Sigillarids and Lepidodendrids, the appearance of the scars of the same species varied much with age ; moreover, the same scar is wholly different in form at the surface from what it is below, as Figs. 1037, 1038 illustrate. The trunk, while woody and firm outside, consisted inside mostly of cellular tissue, with usually a very large pith along the center ; and hence the stumps easily became hollow by decay. Such hollow stumps, filled with sand or clay, are common in the Coal-measures ; and sometimes there remain only casts of them in sand having a scarred exterior. 670 HISTORICAL GEOLOGY. One of the cones of a Lepidodendrid from Pittsburg, Pa., is represented in Fig. 1039. The Stigmarice, which were either roots or under-water-stems of Sigillarids or Lepidodendrids, were often large, many of the fossil stems being four to six inches in diameter. Fig. 1041 represents a portion of a stem, with its rounded impressions or scars. When perfect, each scar was the base of a long and slender leaf-like appendage. 1045-1048. 1046 TERNS. Fig. 1046, Odontopteris Schlotheimi ; 1046, Alethopteris lonchitica ; 1047, Sphenopteris (Hymeno- phyllites) Hildrethi ; 1047 a, portion of the same, enlarged ; 1048, Sphenopteris Gravenhorstii ; 1048 a, portion of the same, enlarged. Figs. 1045-1047, Lesquereux ; 1048, Brongniart. Ferns. Two of the large scars of stems of Tree-ferns are shown in Figs. 1042, 1043 ; and, for comparison, one from a modern Tree-fern (resembling the tree to the left in the sketch, page 666) is represented half-size in Fig. 1044. The trunks of Tree-ferns consist within of vertically plicated woody plates, with more or less cellular tissue between, and not of concentric rings. The twisted plates are sometimes well shown in a transverse section of a fossil trunk from the Coal-measures. The variety of Ferns was very large. Some of the more common forms PALEOZOIC TIME CARBONIC. 671 are represented in Figs. 1045 to 1052. The genus Neuropteris (Figs. 1049, 1050) is one of the most abundant in species. The basal leaves (Figs. 1050, 1052) vary widely in form in the same species, and are sometimes delicately fimbriated. Odontopteris (Fig. 1045) has many species ; and so also Alethop- teris (Fig. 1046), Sphenopteris (Figs. 1047, 1048), and Pecopteris (Fig. 1051). 1049-1056. 1053 FERNS. Figs. 1049, 1049 a, Neuropteris Loschii, parts of the same leaflet; 1050, Neuropteris hirsute ; 1051, Pecopteris arborescens ; 1051 a, a portion of the same, enlarged ; 1052, basal leaf of Neuropteris tenuifolia. EQUISETA. 1053, Asterophyllites equisetiformis ; 1053 a, the same (?) with sporangia at the axils of the leaves ; 1054, A. sublaevis ; 1055, Calamites cannaeformis ; 1055 a, surface-markings of same, enlarged. Fig. 1056, Sphenophyllum Schlotheimi. Figs. 1049-1054, 1056, Lesquereux ; 1055, Brongniart. Equiseta. The more common Equiseta of the Coal-measures are species of Calamites, as in the Devonian. One of the jointed, delicately fluted stems is represented in Fig. 1055 ; and the junction of the flutings of the surface at a joint, in Fig. 1055 a. The Asterophyllites (Fig. 1053) and An- nularice are sometimes branches of the same plant, the former occurring toward its base. Fig. 1053 a shows the sporangia at the base of the leaves. Fig. 1056 represents a common species of Sphenophyllum ; the name alludes to the wedge-shaped leaves ; W. C. Williamson states (1894) that the 672 HISTORICAL GEOLOGY. species are not related in fructification to the Lycopods or Equiseta, or to any known group of Cryptogams. 2. Gymnosperms of the Order of Cycads. The character and fruit of Cordaites has been well illustrated by Lesquereux from specimens obtained at Cannelton, Pa. Fig. 1057 shows the Cycad-like foliage ; and Fig. 1057 a 1057. Fig. 1057, Cordaites costatus ; 1057 a, fruit, with a portion of the attached stem. Lesquereux. represents fruit which occurs at the same locality, and is found there so* closely associated with the leaves as to be probably of the same species. Lesquereux figures the leaves and fruit also of C. Mansfieldi from this locality, a species with much broader leaves, and nuts of a smooth obovate form, 2^- inches long. The Sigillarids are referred to this division of the Gymnosperms by Re- nalt and Dawson, but to the Lycopod tribe by Williamson and most authors.. PALEOZOIC TIME CARBONIC. 673 The fruit of Cordaites (Cordaicarpus) Gutbieri is represented in Fig. 1062. 1058o 1058 c 1060 1062-1068. 1066 FBtnrs. Figs. 1058 a, 6, c, Trigonocarpus tricuspidatus ; a, the exterior husk or rind ; 6, the nut separate from the rind ; c, kernel ; 1059, nut of Trigonocarpus ? ; 1060, T. ornatus ; 1060 a, vertical view of summit, showing the ribs of the surface ; 1061, Cardiocarpus bicuspidatus. Newberry. The Cordaites had a large pith, like that named Artisia and Sternbergia, as figured by Lesquereux on plate Ixxxi. of his Pennsylvania Report. The gen- era Lepidoxylon, Dicrano- phyllum, Tcemophyllum are related to Cordaites, and probably others in which the pith is large. 3. Gymnosperms re- lated to the Yews. The other Gymnosperms of the era, usually called Conifers, were probably related to the Taxineae or Yews, which have single fruit instead of cones, and vary widely in foliage, the leaves sometimes broad, and occasionally Fern-like. From such trees came probably the fossil nuts, as suggested by Hooker. The above figures are from Newberry's Ohio Keport. Fig. 1058 rep- resents one of the three- sided or six-sided fruits, called Trigonocarpus: 1058 a, the husk; 6, the nut; c, the kernel. DANA'S MANUAL 43 FRUITS. Fig. 1062, Cordaicarpus Gutbieri ; 1063, Cardiocarpus elonga- tus ; 1064, C. samaraefonnis ; 1065, C. bisectus ; 1066, Botryoconus (Antholithes) Pitcairniae ? ; 1067, B. priscus ; 1068, Cordaianthus, flow- er (fruit ?) of a Cordaites. Fig. 1062, Lesquereux ; 1063, 1064, 1066- 1068, Newberry ; 1065, Dawson. Fig. 1059 674 HISTORICAL GEOLOGY. is the nut of another species. Figs. 1063 to 1065 represent species of Car- diocarpus; they resemble the fruit of the anomalous Gymnosperms of Africa, Welwitschia (page 435). The peculiar but beautiful fan-shaped leaves, named Wliittleseya elegans by Newberry, are of unascertained relations. Figs. 1066, 1067 are supposed to be fruit of Gymnosperms, in different stages of development ; and Fig. 1068, fruit of doubtful species. Figs. 1066, 1067 have the forms of half developed flowers or leaf-buds, and were called Antholithes by Newberry. They are referred to the Conifers by Grand' Eury. Lesquereux regards Botryoconus prisons (Fig. 1067) as a more advanced stage of B. Pitcairnice. Fig. 1068, Antholithes of Newberry, is the fruit or flower of a Cordaites, according to Lesquereux. ANIMALS. The animal life of the Carboniferous period included, besides marine Invertebrates, terrestrial Mollusks, and a large variety of terrestrial Articulates, as Insects, Spiders, Myriapods ; and, among Vertebrates, besides Fishes and Amphibians, a higher range of life, in true Reptiles. No evidence has been obtained of the existence then of Birds or Mammals. 1. Rhizopods. Shells of Rhizopods, of the shape and size of a kernel of wheat, belonging to the genus Fusulina, Figs. 1069, a, are common in some of the shales and limestones of the Mississippi valley and beyond, in Illinois, Kansas, Utah, New Mexico, California, and elsewhere. In British Columbia, on Fraser's River, at Marble Canon, the Fusulince, of a thick limestone, are associated with a very abun- dant arenaceous Rhizopod, T 3 7 of an inch long, shaped like an elongated shot, which has been referred to the genus Loftusia, and named L. Columbiana. In Europe the Fusulinse are found in Subcarboniferous beds as well as in the Carboniferous and Lower Permian. 2. Actinozoans and Echinoderms. Corals, seldom abundant, are of the genera Lophophyllum, Zaphrentis, Lithostrotion, and others. Lophopliyllum proliferum McChesney occurs in roof shales over coal at Springfield, 111. Crinoids are few compared with those of the Subcarboniferous ; Illinois has afforded about a dozen species ; and Missouri others. In Nevada, Arizona, New Mexico, Nebraska, etc., have been found a few Echinoids of the genus Archceocidaris. 3. Molluscoids and Mollusks. The Brachiopods are similar in genera to those of the Subcarboniferous, though partly of new species ; and the same is true in the main of the marine Gastropods, Lamellibranchs, and Cephalo- pods. Some of the characteristic species are here figured : a characteristic Productus in Fig. 1070, a Chonetes in 1071, and Gastropods in 1076 to 1080. But besides marine Gastropods, the Coal-measures have afforded the first known of terrestrial shells. One of the small land-snails, or Pulmonates, is represented, a little enlarged, in Fig. 1081, a species found in the Nova Scotia Coal-measures, and described by Dawson ; and Figs. 1082, 1083, from F. H. Bradley, show the forms of two others from Illinois. PALEOZOIC TIME CARBONIC. 675 Among the Cephalopods, the Nautiloids, as Hyatt observes, reach their greatest expansion in the Carboniferous period. They include species of 1070-1073. BBAOHIOPODS. Fig. 1070, Productus Nebrascensis ; 1071, Chonetes mesolobus ; 1072, Spirifer cameratus ; 1078, Seminula (Athyris) subtilita. Fig. 1070, Hall ; 1071-1073, Meek. 1074 1074-1075. 1075 LAMELLIBRANCHS. Fig. 1074, Macrodon carbonarius ; 1075, Allorisma subcuneata. Fig. 1074, Cox ; 1075, Meek. 1076 1076-1080. 1078 GASTROPODS. Fig. 1076, Pleurotomaria tabulata ; 1077, Bellerophon carbonarius ; 1078, Pleurotoinaria sphfieru- lata ; 1079, Macrocheilus (?) fusiformis ; 1080, Dentaliutn subheve. Figs. 1076, 1077, de Koninck ; 1078-1080, Hall. Orthoceras, Cydoceras, Phacoceras (P. Dumbli Hyatt Figs. 1084, a, reduced one half), Temnochilus (T. crassum Hyatt, Fig. 1085), and a number of genera with longitudinal ridges and keels, as in the Trigonoceratidae. There are also species of the Goniatites group. 4. Worms. Sea-worms or Annelids have been supposed to be represented by a small coiled shell, referred to the genus Spirorbis, found attached to 676 HISTORICAL GEOLOGY. the leaves and stems of submerged plants. The specimen figured is from Nova Scotia (Dawson). They are reported also from the Pennsylvania Coal-measures. 1081. 1082. 1081-1085. 1084 a. 1084. PULMONATE GASTROPODS. Fig. 1081, Pupa vetusta (x |) ; 1082, P. Vermilionensis ; 1083, Dawsonella Meeki. NAUTILOID CEPHALOPODS. Figs. 1084, a, Phacoceras Dumbli (x i); 1085, Temnochilus crassum. Fig. 1081, Dawson ; 1082, 1083, F. H. Bradley ; 1084, 1085, Hyatt, '90. 1086. 5. Limuloids. Species of the group of Eurypterids were common. Speci- mens of one of them, four to ten inches long, the Eurypterus Mansfieldi of C. E. Hall, are found in the shale below the Darlington cannel coal, near Cannelton, Pa., laid out among Ferns and Calamites, as represented in Fig. 1087. The species probably lived in fresh- water marshes and ponds. In addition, the modern tribe of Limulids had its species : one from Morris, 111., is represented in Fig. 1088. Another species, Cyclus Americanus of Packard, had an even, nearly circular outline, without a telson, and closely resembled an embryonic Limulus. 6. Crustaceans. Trilobites were rare, and of the genera Phillipsia, Grif- fithides and Brachymetopus. Under Crustaceans there were also various species of modern aspect, represented in Figs. 1089 to 1091, the latter two, if not all three, true Decapods. The Myriapods were mostly related to the inferior lulus tribe nearly cylindrical species (as Figs. 1092, 1093) having often two pairs of legs to a body segment. But in one species, the Palceocampa anthrax of Meek and Worthen, from Illinois, the body had but 10 segments ; and on its Spirorbis carbonarius. PALEOZOIC TIME CARBONIC. 677 back were tufts of minute spines, so that it looked much like some cater- pillars. 7. Arachnids. Among Arachnids, there were Spiders (Fig. 1095) as well as Scorpions (Fig. 1094). 1088. 1087. Fig. 1087, Eurypterus Mansfieldi. C. E. Hall, '77. Fig. 1088, Prestwichia Danse. Meek and Worthen. All the species represented in Figs. 1089-1093 are from the Coal-measures at Mazon Creek, in Morris, 111., where they occur in the centers of concretions, and were the nuclei about which the concretions were formed. Thus entombed, they were safe against removal by infiltrating waters. The locality has afforded 16 species of Myriapods and nearly a dozen kinds of Spiders, besides Scorpions. 8. Insects. Insects are found at Morris, under the same conditions (besides Ferns and other plants), and in the shales of the Coal-measures elsewhere. The Neuropter-like, or Neuropteroid, species are common (Figs. 1096, 1097), and still more so the Orthopteroid, and especially those of Orthopteroids related to the Cockroach, a wing of one of which is shown in Fig. 1098 j and less abundantly the species related to the modern Phasma and Locust, the Protophasmids (Fig. 1099). Scudder enumerates in a recent paper 133 American species of Coal-measure Cockroaches from the Coal- measures of the Continent, pertaining to 14 different genera, and nearly all are of his own describing. Of these, 56 species are from the Waynesburg coal-bed at Cassville, W.Va., where the beds are Permian, according to I. C. White ; 12 from Providence, R.I. ; 22 from the Lower Barren Coal- 678 HISTORICAL GEOLOGY. measures at Richmond, O. ; 7 from Pittston, Pa., and as many from Cannel- ton; 17 from Illinois, 5 from Missouri, 1 from Arkansas, 1 from Kansas, 1 from Nova Scotia, and 3 from Cape Breton ; and only in one case has a species 1089. CRUSTACEANS. Fig. 1089, Acanthotelson Stimpsoni; 1090, Palseocaris typus (x3) ; 1091, Anthracopalsemon gracilis. MYRIAPODS. 1092, Xylobius sigillarise ; 1093, Euphoberia armigera. Figs. 1089-1091, 1098, Meek and Worthen ; 1092, Dawson. 1095 a. 1094-1095. ARACHNIDS. Fig. 1094, Eoscorpius carbonarius ; a, one of the combs; 1095, Arthrolycosa antiqua; a, profile, showing the elevation of the cephalothorax and the position of the legs. Fig. 1094, Meek and Worthen, '68 ; 1095, Beecher. PALEOZOIC TIME CARBONIC. 679 been found at two localities. All of the great marshes of the Continent appear to have been infested by Cockroaches. Probably the JSfeuropteroids were equally numerous, although less common as fossils. The Insect fauna 1096-1099. 1098. 1097. 1099. NETTEOPTEKOID INSECTS. Fig. 1096, Miamia Bronsoni ; 1097, Gerarus Danse. ORTHOPTEROIDS. Fig. 1098, Etoblattina venusta, anterior wing; 1099, Paolia vetusta (xf). Fig. 1096, D.; 1097, Scudder, '68; 1098, Lesquereux ; 1099, S. I. Smith. was also remarkable for the large size of many species. A Protophasmid of the genus Haplophlebium of Scudder, from Cape Breton, related to the Locust, had an expanse of wing of seven inches. In a Neuropteroid of the genus Megathentomum, from Illinois, the breadth of a wing was two inches, and the length over three. No Beetles (Coleopters) had been found in the American Coal-measures up to 1894. The absence of Butterflies and all Lepidopters, and of Hymenopters and Dipters, is considered certain. 9. Vertebrates. Fishes. The class of Fishes in the Carboniferous included only Selachians and Ganoids ; and the Ganoids had still the ancient feature of vertebrated tails. Two of these Ganoids, one of them, a Coelacanthus, having the vertebral column extending along the middle of the tail, the other, a Eurylepis, are illustrated in Figs. 1100, 1101 : they are from a black, very carbonaceous shale, at Linton, Ohio, which abounds in Fishes, and has 680 HISTORICAL GEOLOGY. afforded Newberry nine species of Eurylepis, three of Codacanthus, and a Palceoniscus, besides some Selachian remains. A Selachian tooth from Illinois, related to the Petalodus from the Sub- carboniferous, is represented of reduced size in Fig. 1102. Fart of the 1100-1104. 1100. 1103. GANOIDS. Fig. 1100, Eurylepis tuberculata ; 1101, Coelacanthus elegans. SELACHIANS. Fig. 1102, Petalodus destructor ; 1103, fin-spine ; 1104 a, b, dermal tubercles of Petrodus occidentalis. Figs. 1100-1102, Newberry ; 1103, F. H. Bradley. lower jaw of a Cestraciont Shark, named by Newberry and Worth en after Agassiz, is represented of reduced size in Fig. 1105 ; the actual length of the specimen was nearly 24 inches, and the estimated length of the Shark 1105. CESTBACIONT SHARK. Agassizodus variabilis (.xg). Newberry and Worthen. 15 to 20 feet. The teeth of the species have been found in the Upper Coal- measures of Kansas, Illinois, and Iowa. A mouth so paved was a most effective crushing organ. Fin-spines of Sharks occur of many kinds and sizes. A portion of a small one is represented in Fig. 1103. The bony tubercles, Figs. 1104 a, &, were found with the spine, and are supposed to be from the surface of the body of the same Fish. Large spines of species of Edestus, having one edge armed with great teeth, as in Figs. 1106, 1107, have been found in the Coal-measures of Indiana, Illinois, and Arkansas. In E. minor of Newberry, Fig. 1107, the teeth are nearly two inches long, and in E. giganteus Newberry, Fig. 1106, PALEOZOIC TIME CARBONIC. 681 nearly three long and two broad. The figure of the latter represents, reduced, only a small portion of the specimen ; as figured by Newberry the spine has five teeth ; when entire it was probably 18 inches in length, and occupied, along the body of the Shark, according to Newberry, the place of the posterior dorsal fin. It could thus rip open its prey when swimming underneath it, and slash effectually in defense. Amphibians. Besides footprints, which thus far are the only evidence of Amphibians in the Subcarboniferous, the Coal-measures have afforded 1106-1107. FIN-SPINES OF SHARKS. Fig. 1106, Edestus giganteus ; 1107, E. minor (each x|). Newberry. remains of skeletons. They show that many of the earlier kinds were much like their predecessors, the higher Ganoid nnd Dipnoan Fishes, in having a bony cranium instead of one with large open spaces and little bone, like the modern Frog ; and in allusion to the ivell-roofed head, they are called Stegocephs by Cope. Among modern Amphibians only some snake-like kinds have a similar cranium. They are also like the Fishes in their teeth, the most of them having the enamel inflexed along the surface grooves, producing the Labyrinthine texture which suggested for the species the name of Labyrintho- donts. Further, they generally have biconcave vertebrae, like Fishes. Moreover, the Amphibians occur of all grades from (1) Shake-like forms without limbs, to (2) those with feeble swimming organs ; and thence to (3) the four-limbed species of various sizes, up to kinds as large and formid- able as Alligators., It is interesting to note also that the feet have five toes (or less), and the fingers the modern number of bones. The Coal-measures of Ohio, at Linton, afforded Newberry numerous 682 HISTORICAL GEOLOGY. specimens, and other regions have added to the number. Of the snake-like species, part without limbs, and others with feeble limbs, Cope has made out over a dozen species from Linton. Phlegethontia linearis of Cope had no limbs, and the proportion of a Whip-snake; and Molgophis macrurus was nearly of the size of the common Rattlesnake. One of these nearly snake-like species, Ptyonius serrula of Cope, is represented in Fig. 1112 ; it had hind- limbs, but no fore-limbs. A four-limbed, Salamander-like species, Pelion Lyelli, from Linton, described in 1857 by Wyman, is shown in Fig. 1109 ; and in Fig. 1108, another species, the Amphibamus grandiceps of Cope, from Illinois. Leptophractus obsoletus Cope, from Linton, of Alligator size, had stout teeth three fourths of an inch long. Nova Scotia has afforded species of Dendrerpeton and Hylerpeton of Owen, and of Hylonomus of Dawson, the last peculiar in having a slender head. The Nova Scotia species come mostly from the South Joggins, where they were first discovered by Lyell and Dawson in 1851. They were found in the sandstone filling the once hollow trunks of large Sigillariae, along with land-shells (Pupa vetusta, Fig. 1081) and Myriapods (Xylobius sigillarice, Fig. 1092); and leaves of Ferns and Cycads, and this mode of occurrence suggested the name Dendrerpeton (or tree-reptile). The conditions appear to show that the hollow stumps, the poor pithy wood of which had decayed as they stood in the marshes, were the resort of the Amphibians, and a catch-place for other species of the wet region ; or, that the shells were the food of the Amphibians, as Dawson suggests, who states that he has found, in the stomach of a recent Menobranchus (M. lateralis Harlan), as many as 11 unbroken shells of the fresh- water snail, Physa heterostropha. In 1876, Dawson obtained at the Joggins, from a stump 18 inches in diameter, remains of 13 Amphibian skeletons, pertaining probably to six species. The Baphetes planiceps Owen, of Nova Scotia, had a head 3^ inches broad. The South Joggins has also afforded, about 5000 feet below the top of the Coal-measures, two biconcave vertebrae (Fig. 1111, with the cross-section, 1111 a), which are the basis of the species Eosaurus Acadianus Marsh. The vertebrae resemble those of an Enaliosaur (Sea-Saurian, page 785), but, as observed by Huxley, from his observations on the Anthracosaurus Russelli of the British Coal-measures, and, as recognized by Marsh, they probably belonged to a large Amphibian. Footprints of Amphibians occur in the Coal-measures of Pennsylvania. Indiana, Illinois, Kansas, and Nova Scotia. Figs. 1113 to 1116 represent tracks of four out of five species described by Marsh from the middle of the Coal-measures in Osage, Kan. All are from one surface about 12 feet square. Between the right and left tracks in Fig. 1113, there is the im- pression of the tail. In the tracks of Dromopus, having long slender toes, the phalanges or joints are very distinct, and on account of the form, Marsh questions whether the species may not have been Reptilian; but he regards the sweep of the foot in walking, indicated by the lines between the two tracks to the right, as favoring Amphibian relations. So many kinds of 1108. PALEOZOIC TIME CARBONIC. 1108-1112. 683 AMPHIBIANS. Fig. 1108, Amphlbamus grandiceps (x 2) ; 1109, Pelion Lyelli ; 1110, Molgophis macrurus?; 1111, 1111 a, Eosaurus Acadianus, vertebra (x J) ; 1112 a, 6, c, d, Ptyonias serrula. Figs. 1108, 1109, 1110, J. Wyman ; 1111, Marsh ; 1112, Cope. 684 HISTORICAL GEOLOGY. tracks on so small an area show that the Amphibians of the period were in great numbers. 1113. 1114. 1115. 1116. FOOTPRINTS OF AMPHIBIANS. Fig. 1113, Nasopus caudatus; 1114, Limnopus vagus; 1115, Dromopus agilis ; 1116, Baropus lentus (x^). Marsh, '94. LIFE OP THE PERMIAN PERIOD. PLANTS. The vegetation of the Upper Barren Coal-measures or Permian strata of Pennsylvania and West Virginia (page 651), is characterized, as shown by Fontaine and White, by the absence of Lepidodendrids ; by the rarity of Sigillarice, only two being known; by the large number of species of Ferns (over 30) of the genus Pecopteris, some arborescent, and, only a third PALEOZOIC TIME CARBONIC. 685 of them known to occur in the Coal-measures, with other species of the related genera Cymoglossa, Goniopteris, Callipteridium, Callipteris, and also of Neuroptens, Sphenopteris, Alethoptens, Odontoptens ; many species of the Equisetum tribe, of the genera Sphenophyllum, Annularia and Equisetites, and the continuation of the Calami tes, C. Suckovi; also, the occurrence of Cycads of the Permian genus Baiera, and of the remarkable Conifer of the Yew family, of the new genus Saportcea, whose leaves were nearly four inches 1117. 1117-1121. 1118. 1117 a. MOLLUSKS. Fig. 1117, HIT a, Pseudomonotis Hawni; 1118, Myalina perattenuata ; 1119, Bakewellia parva; 1120, Pleurophorus subcuneatus ; 1121, an undetermined Gastropod. Meek. wide. Only 20 per cent of the species have been found in the Coal-measures, and over 25 per cent occur in the Permian of Europe, and the genus Cymo- glossa is confined abroad to the Permian. ANIMALS. 1. Brachiopods, 1122. Mollusks. Many of the com- mon Coal-measure species con- tinue on into the Permian. Some of these are : Productus semireticulatus, P. Rogersi, Chonetes Fleming!, Spirifer cameratus, Seminula (Athyris) subtilita; and with these are others confined to the Permian, as Meekella (Orthisina) Shu- mardana, Productus Norwoodi, Monotis Halli, M. speluncaria, M. variabilis, Pseudomonotis Hawni var. ovata (Fig. 1117), Myalina perattenuata (Fig. 1118), M. Permiana, M. Halli, M. recta, Bakewellia parva (Fig. 1119), Pleurophorus sub- cuneatus (Fig. 1120), Schizodus Rossicus, Nautilus eccentricus, N. Permianus, Cyrtoceras dorsatum; and Texas has afforded C. A. White five species of Medlicottia Copei. C. A. White. 686 HISTORICAL GEOLOGY. Nautilus, a Goniatites, a species of Medlicottia (Fig. 1122), and other Ammon- ites of the genera Ptychites, Popanoceras, and Wdagenoceras, which are Permian in Russia and India. 2. Crustaceans, Insects. A Trilobite, of the genus Phillipsia, has been ob- served in the Permian of Missouri (Swallow); and a Cockroach, Gerablattina balteata Scudd., in West Virginia and Ohio beds. 1123. 1123 a. AMPHIBIAN. Eryops megacephalus (x J). Cope, '81. 3. Vertebrates. To Fishes and Amphibians the Permian beds of America, like those of Europe, added Reptiles. PALEOZOIC TIME CARBONIC. 687 The Fishes were of Coal-measure types of Ganoids and Selachians. The genera of the former included Ctenodus, Ptyonodus, and others ; also Cerato- dus, a Dipnoan genus, which here has its first known species, while its last is still living in Australia ; the Permian, C. favosus of Cope, is from Texas. Sharks occurred of the genus Diplodus, and along with them spines of Ortha- canthus, which have been shown to have belonged to Diplodus, as suggested by Dawson in 1869 from the association of specimens in the Pictou coal- field, Nova Scotia. The Amphibians were, like the earlier, mostly Stegocephs. Fig. 1123 of the cranium of Eryops megacephalus of Cope, from Texas, shows that the head had the well-roofed character to which the name Stegoceph alludes ; and the length of the cranium, over 22 inches, indicates a large species. Two long, narrow-headed species, Cricotus heteroclitus (Fig. 1124) and C. 1124. AMPHIBIAN. Cricotus heteroclitus (x ). Cope. Oibsoni Cope, have been found in the Permian of Danville, eastern Illinois, and the former also in northern Texas. The Permian Beptiles, the earliest of the class, belong to the tribe JRhynchocephalia, which, like the genus Ceratodus among Fishes, is nearly extinct. Only two species, of the genus Sphenodon (or Hatteria), now exist, and these are confined to New Zealand a piece, like New Guinea, of a now half-extinct continent, Australia. One of the earliest of the species is proba- bly the Mesosaurus (Stereosternum) tumidus of Cope (Fig. 1125), from beds containing shells of Schizodus in the Permo-Carboniferous of Sao Paolo, Brazil. It may be, however, from a bed below the Permian. Cope mentions its relations to the Amphibians and closer to the Khynchocephalian Reptiles, and the interesting fact, of primitive aspect, that the foot, as the figure shows, has a tarsal bone (1 to 5 in figure) to each of the five metatarsals (I to V), five in all, or the normal number, instead of four, which is the largest number in later Reptiles. Other Permian reptiles, but probably later stratigraphically, are those of Clepsydrops of Cope, three from Texas and as many from Illinois ; of 688 HISTORICAL GEOLOGY. Dimetrodon of Cope, which has several Texas species, remarkable for the great length of the neural spines of the lumbar vertebrae which supported the broad dorsal fin characteristic of the genus ; and other related genera, for which Cope instituted the family of Theromora made by some a part of 1125. Mesosaurus tumidus (natural size); 1-5, tarsals ; I-V, metatarsals. Cope. the group Anomodontia. Other related species, from New Mexico, are the Ophiacodon grandis Marsh, about 10 feet long ; also species of Sphenacodon and Notliodon of Marsh. These early E/hynchocephalians and Anomodonts combine Amphibian and Mammalian characteristics along with the Keptilian. Characteristic Species. 1. CARBONIFEROUS PERIOD. PLANTS. 1. Seaweeds are rare in the Coal-measures. A Spirophyton, like S. cauda- galli (page 582), has been reported by Lesquereux as occurring in sandstone, probably of this era, or of the Subcarboniferous, in Crawford County, Ark. Species of the genus Caulerpites have been observed in Pennsylvania, Illinois, Indiana, Missouri, in both the Lower and Upper Coal-measures. Chondrites Colletti Lsqx. was obtained near Lodi, Ind., overlying a thin coal-bed at the base of the Coal-measures. Lesquereux remarks that, although the iron-stone concretions have preserved the most delicate parts of Ferns and Insects, no trace of a Fungus or Lichen has been found in them. He observed elsewhere, however, evidences of parasitic Fungi. A large Fungus, having some resemblance to an Agaricus, has been reported, with illustrations, by H. Herzer, from the Lower Kittanning coal-bed of Tuscarawas County, Ohio, and named Dactyloporus archceus. 2. Lepidodendrids. Fig. 1033, part of the surface of the Lepidodendron aculeatum Sternb., a common species both in the United States and in Europe ; 1034, L. clypeatum Lx. ; 1036, L. Veltheimanum St., which is also Subcarboniferous and European ; 1035, Halonia pulchella Lx., Arkansas. Other common species, and of wide range, are Lepi- dodendron Sternbergii (also Subcarboniferous), L. dichotomum Brgt., L. modulatum Lx. 3. Sigillarids. Fig. 1037, Sigillaria Sillimani Brgt. , Pa., Ind. ; 1038, 8. Pittstonana Lx., Pittston, Pa., Ky. PALEOZOIC TIME CARBONIC. 689 4. Ferns. Fig. 1042, scar of the Tree-fern, Stemmatopteris punctata Lx., Gate vein, Pa. ; 1043, same of Megaphyton McLayi Lx., 111. ; 1044, scar of Cyathea compta, a species now growing in the islands of the Pacific ; 1045, Odontopteris Schlotheimi Brgt., Pa. , Ohio, 111., Europe ; 1046, Alethopteris lonchitica Brgt., most common in the Lower Coal-measures, Pa., etc. ; 1047, Sphenopteris (Hymenophyllites) HildrethiljX., Kanawha Salines; 1047 a, same, enlarged ; 1048, JS. Gravenhorstii Brgt., R. I., Mo. ; 1048 a, same, enlarged ; 1049, a, Neuropteris Loschii Brgt. , and 1050, Neuropteris hirsuta Lx. , from figures by Lesquereux, common in the Upper Coal-measures, in Ohio and Kentucky, and the former particularly abundant in the Pomeroy bed ; 1051, Pecopteris arborescens Brgt., Pa., Ohio ; P. cyathea Brgt. and P. unita Brgt., common ; 1052, Neuropteris tenuifolia Lx., Shamokin, Pa. In Arctic America, on Melville Island, impressions of a Sphenopteris have been observed in connection with the coal. 5. Calamitids. Fig. 1056, Calamites cannceformis Schloth., Potts ville conglomerate and Lower Coal-measures ; 1054, Asterophyllites sublcevis Lx. ; 1053, A. equisetiformis Lx., Pa., R. I. ; 1055, Sphenophyllum Schlotheimi Brgt., through all the Coal-measures. 6. Gymnosperms. Cordaites borassifolius Ung., a common Coal-measure species; Fig. 1057, Cordaites costatus, Lx. , Cannelton, Pa. ; 1057 a, fruit of same ; 1062, Cordaicar- pus Gutbieri d'Eury, Cannelton ; 1063, Cardiocarpus elongatus Newb., Ohio ; 1065, C. bisectus Dn., Nova Scotia; 1064, C. samarceformis Newb., Ohio; 1058 a, b, c, Trigono- carpus tricuspidatus Newb., Ohio, representing the rind, the nut, and the kernel; 1059, nut of another Ohio species, figured by Newberry, but not described ; 1060, a, T. ornatus Newb., Ohio ; 1061, Cardiocarpus bicuspidatus Newb., Ohio. Figs. 1066 and 1067 are made the type of the genus of Conifers, Botryoconus of Grand'Eury, being immature fruits. The specimens, and that of the fruit, Fig. 1068, are from the Lower Coal-measures of Youngstown, Ohio. The Rhode Island coal region, according to Lesquereux, belongs to the Upper Productive Measures. See Am. Jour. Sc., xxxvii., 229, 1889. For lists of species of plants characteristic of the several subdivisions of the Carbo- niferous period, and their geographical distribution in America, see Lesquereux's Penn- sylvania Report, No. P, page 855 and beyond, and also page 636. According to Lesquereux the following species commence in the Pottsville conglomerate, or the beds next above, and continue through the Coal-measures : The names of species not in the Conglomerate have a dash before them ; those which have a dagger after them continue into the Permian ; and those starred are also European. Calamites Suckovi t*, C. ramosus *, C. cannceformis *, C. approximatus *, C. Cistii * ; Asterophyllites equisctiformis*, A. foliosus*, Annularia longifolia t*, A. sphenophyl- Zoidesi*, Sphenophyllum Schlotheimi*, S. longifoUum^, 8. emarginatum*, Neuropteris hirsuta t*, N. flmbriata t, N. inflata, N. angustifolia*, N. Loschii*, N. tenuifolia*, N. capitata, N. Germari*, N. cordata t*, Odontopteris Schlotheimi*, 0. sphenopteroides ; Alethopteris Serlii*, A. lonchitica* ; Pseudopecopteris nervosa, P. muricata*, P. anceps, P. irregularis*, P. nummularia *, P. decipiens, P. latifolia*; Pecopteris acuta*, P. serrulata, P. arborescens^*, P.notatri, P.pteroides^*, P. erosa* ; Sphenopteris (Hymenophyllites) spinosa*, S.furcata*, S. tridactylites * ; Ehacophyllum lactuca]*, E.filiciforme* ; Lepi- dodendron Sternbergii*, L. aculeatum, L. Veltheimanum*, L. vestitum, L. clypeatum, L. dichotomum*, L. obovatum*, L. modulatum, L.rimosum* ; Ulodendron majus*, U. punctatum; Knorria imbricata*; Lepidophloios laricinus* ; Sigillaria monostigma, S. Brardii t*, 8. Menardi*, S. tesselata *, S. mammillaris t, S. Lescurii, Cordaites diversi- folius, C. borassifolius* The genera especially characterizing the Lower Coal-measures are : Megalopteris, Tceniopteris, Neriopteris, Hymenophyllites section of Sphenopteris, Eremopteris, Knorria, Lepidophloios, Lepidodendron, Sigillaria, Cordaites, Whittleseya. DANA'S MANUAL 44 690 HISTORICAL GEOLOGY. For Reports on American coal plants with figures, see Indiana Geol. Hep. for 1883, by Lesquereux ; Illinois Geol. Rep., vols. ii. and iv., by Lesquereux ; Ohio Pal., vols. i. and ii., by Newberry ; Pennsylvania Geol. Rep., No. P, by Lesquereux, 1st vol. text, 2d vol. plates, 3d vol. text and plates, 1880-84. On the Permian flora, see Fontaine and White, Pa. Geol. Hep., No. PP, 1880. ANIMALS. 1. Rhizopods. Fig. 1069, Fusulina cylindrica of Fisher, is a Russian spe- cies, to which the American specimens in part are referred. F. elongata Shumard, F. robusta, F. ventricosa, and F. gracilis of Meek, are supposed to be probably varieties of it. Loftu- sia Columbiana G. M. Dawson, Q. J. G. S., xxxv., 74. Dentalina priscilla Dn., from Nova Scotia, consists of a single series of cells. 2. Actinozoans. Syringopora multattenuata McCh., Campophyllum torquium Ow., etc. 3. Echinoderms. Crinoids, of the genera Poteriocrinus, Actinocrinus, Cyathocrinus, Zeacrinus, Delocrinus, Scaphiocrinus, Eupachycrinus, Agassizocrinus, Acrocrinus, etc. 4. Molluscoids. Fig. 1072, Spirifer cameratus Mort., Lower and Upper Coal-meas- ures, in Ohio, Ky., Ind., 111., Mo., Utah, etc. ; 1070, Productus Nebrascensis Ow., 111., Kan., N. Mex. ; 1071, Chonetes mesolobus N. & P., a common species ; 1073, Seminula subtilita Hall, common in the Coal-measures ; Spiriferina Kentuckensis Upper Coal-measures, 111., Ky., Mo., and near Pecos village, N. Mex.; Spirifer lineatus Phill., Meekella striatocostata Cox, 111., Mo., Iowa; Orthis Pecosi Marcou; Dielasma (Terrebratula) bovidens Mort.; Derby a (Streptorhynchus) crassa M. & H. ; Waldheimia ? (Cryptacanthia) compacta W. & St. John. The following first appeared in the Subcarboniferous, and are continued into the Carboniferous : Productus punctatus (Fig. 1013, page 642), P. cora, P. muricatus, P. semireticulatus (Fig. 423, page 427), Spirifer lineatus. 5. Mollusks. Lamellibranchs. Fig. 1074, Macrodon carbonarius M., Upper Coal- measures, Ky. ; 1075, Allorisma subcuneata M. & H., Kan. ; Aviculopecten rectilaterarius Cox, Upper and Lower, Avicula (Gervillia) longa M., Nuculana bellistriata M., Cardio- j- morpha Missouriensis Shum., Solenomya radiata M. & W., Myalina perattenuata M. & H., ' M. recurvirostris M. & W., Schizodus amplus M. & W., all from 111. Entolium avicula Swallow, Kan. ; Pinna peracuta Shum., Mo., Kan. ; Lima retifera Shum., Kan. ; Mytilus [Modiola (?)] Shawneensis Shum., Kan. ; Monodon, species of Monopteria, Pseudomo- notis, Placunopsis, etc.; Modiola Wyoming ensis~Lz&, Wyoming, Pa.; Anthracomya (Naiad- ites) carbonaria Dn., N. Scotia ; A. elongata Dn., N. Scotia ; A. Icevis Dn., N. Scotia. 6. Gastropods. Fig. 1077, Bellerophon carbonarius Cox (often referred to B. Urii Fleming), Upper Coal, Ky. ; 1076, Pleurotomaria tabulata Con. ; 1078, P. sphcerulata Con. ; P. carbonaria N. & P., P. Graymllensis N. & P. ; 1079, Macrocheilus (?) fusiformis H., M. Newberryi Stevens, M. ventricosus H., Iowa, Mitrchisonia minima Swallow, Mo. ; 1080, Dentalium sublceve H., D. Meekanum Gein., Neb. and 111. ; Straparollus pernodosus M. & W., 111. ; Chiton carbonarius Stevens, Straparollus subrugosus M. & W., 111., Loxonema semicostatum M., Aclis robusta Stevens, Streptaxis Whitjieldi M., all from Illinois ; Naticopsis. Also the Land-snails (Helix family), Fig. 1081, Pupa vetusta Dn., half an inch long, Coal-measures, Joggins, N. Scotia ; 1082, Pupa Vermilionensis Bradley, Vennilion County, 111., in a concretionary limestone ; 1083, Dawsonella Meeki Bradley, same locality. For Cephalopods of the Carboniferous, see papers by Shumard, McChesney, Swallow, Hall, Hall and Whitfield, and the Geological Reports of Illinois (Meek and Worthen), Missouri (Swallow), Texas (Hyatt). Some of the Nautiloids of the Carboniferous, part of them new species, as named and figured by Hyatt in the second Annual Texas Geological Report are : Temnochilus con- chiferum, Tex. ; T. Forbesanum, Tex. (Nautilus F. of McChesney); T. latum, Meek and Worthen, Kan. ; T. depressum, Kan. ; T. crassum, Kan. ; Metacoceras cavatiforme, Kansas PALEOZOIC TIME CARBONIC. 691 City, Mo. ; M. dubium, Kan. ; M. Walcotti, Tex. ; M. Hayi, Kan. ; M. inconspicuum, Kan. ; Tainoceras cavatum, Tex. ; Domatoceras umbilicatum, Kan. ; Asymptoceras New- toni, Kan. ; A. capax (Cryptoceras capax, Meek and Worthen), Mo. ; Phacoceras Dumbli, Tex. ; Ephippioceras divisum (Nautilus divisus of White and St. John) ; Endolobus gib- bosus, Tex. They are mostly large species, 4 to 6 inches in diameter. 7. Worms. Fig. 1086, Spirorbis carbonarius Dn. ; also, S. arietinus Dn. 8. Limuloids. Fig. 1088, Prestwichia Dance = Euproops Dance of M. & W., Morris, 111.; P. longispina Packard, Pittston, Pa.; Dipeltis diplodiscus Packard, Mazon Creek, 111.; Cyclus Americanus Packard, Mazon Creek, 111. (Mem. Nat. Acad. Sc., iii., 14, 1888). 9. Crustaceans. (a) Trilobites. Phillipsia Missouriensis, P. major, P. Cliftonensis of Shumard, from the Upper Coal of Missouri ; P. (Griffithides) scitula M. & W., 111., Ind., and Neb. ; P. (Griff.) Sangamonensis M. & W., Upper Coal, 111. (b) Entomostracans. Cythere Americana Shum., Upper C., Mo.; Leaia tricarinata M. & W., Upper Coal-measures, 111.; Dithyrocaris carbonaria M. & W., 111.; Ceratiocaris sinuata M. & W., 111. (c) Decapods. Tig. 1089, Acanthotelson Stimpsoni M. & W., Morris, HI.; A. Event M. & W., Morris, 111.; 1090, Palceocaris typus M. & W., Morris, 111.; 1091, Anthraco- palcemon gracilis M. & W., Morris, 111.; A. Hillanus Dn., N. Scotia. 10. Myriapods. Mazon Creek, 111., has afforded species of a dozen genera, including Palceocampa anthrax M. & W., Acantherpestes major M. & W., Euphoberia armigera M. & W., and 10 other species of the genus ; Anthracerpes typus M. & W., Eileticus anthra- cinus Scudder, Xylobius Mazonus Sc., Trichiulus villosus Sc., and others of Archiulus, llyodes, etc. In Nova Scotia have been found Xylobius sigillarice Dn. (Fig. 1092), JT. fractus Sc., X. similis Sc., Archiulus Dawsoni Sc., A. Lyelli Sc., A. euphoberioides, and others. 11. Arachnids. Besides the Scorpion of Fig. 1094, Mazon Creek has afforded Mazonia (Eoscorpius) Woodiana M. & W., Architarbus rotundatus Sc., allied to the Phalangidse, Arthrolycosa antiqua Harger (Fig. 1095), Geraphrynus carbonarius Sc., the long-tailed Geralinura carbonaria Sc. From Arkansas has come Anthracomartus trilobitus Sc. ; from Rhode Island, another species of Anthracomartus' from Nova Scotia, Mazonia Acadica Sc. 12. Insects. (a) Neuropteroids. From Morris, 111., Miamia Bronsoni D., Hemeris- tia occidentalis D., Chrestotes Dance Brgt., C. lapidea Sc., Megathentomum pustulatum Sc., Genentomum validum Sc., Anthracothremma robusta Sc., and others. From Pittston, Pa., species of Dieconeura and Polyernus. (6) Orthopteroids. Of the Cockroach group there have been found : at Mazon Creek, 4 species of Mylacris, 2 of Promylacris, 2 of Paromylacris, 1 of Archimylacris, 2 of Etoblat- tina, 1 of Progonoblattina, and 1 of Oryctoblattina ; in Pennsylvania, 6 of Mylacris, 2 of Neomylacris, 1 of Archimylacris, 3 of Lithomylacris, 1 of Promylacris, 1 of Etoblattina, 1 of Gerablattina ; at Cassville, W. Va., 6 of Etoblattina, 15 of Gerablattina, 1 of Anthra- coblattina, 3 of Poroblattina, and 1 of Petrablattina ; at Richmond, Ohio, 17 of Eto- blattina, 3 of Gerablattina, and 2 of Poroblattina ; near Providence, R. I., 8 of Etoblattina, 2 of Gerablattina, and 1 of each Mylacris and Microblattina / and a few others in Missouri, Kansas, Arkansas, Nova Scotia, and Cape Breton. Orthopters of the Proto- phasmid type occur at several of the above localities. Of Carboniferous Hemipteroid Insects, which are not uncommon in Europe, a species, Phthanocoris occidentalis, occurs near Kansas City, Mo. Of Coleopteroid Insects, no American species have yet been reported. The above lists of fossil Myriapods, Arachnids, and Insects are from Mr. Scudder's publications and correspondence. See his Bulletin No. 31, U. S. G. S., for a review of the subject up to 1886 ; also, Bulletin No. 71, 1891, for a full index by him to the known fossil 692 HISTORICAL GEOLOGY. Myriapods, Arachnids, and Insects of the world, with references to all published papers and works on the subject, covering 744 octavo pages. 13. Vertebrates. (a) Fishes. Ganoids. J?ig.llQQ,EurylepistuberculataNev?l).; 1101, Ccelacanthus elegans Newb., Linton, Ohio, remarkable for not having the tail heterocercal, although strictly vertebrated ; 8 other species of Eurylepis, 2 of Ccelacanthus, and 3 of RMzodus, have been described by Newberry from Linton, also Palceoniscus scutigerus and P. peltigerus Newb., Ohio ; P. Leidyanus Lea, Pa. ; P. gracilis N. & W., 111.; P. Browni of Albert Coal Mine, N. B. ; P. Jacksoni Dn. Other Ganoids occur, of the genera Mega- lichthys, Amblypterus, Pygopterus, and Rhadinichthys, in the Coal-measures of the United States and Nova Scotia. Among Selachians, the following European genera have been recognized in the Coal- measure limestones of Pennsylvania, Ohio, Indiana, Illinois, etc., the species being gen- erally distinct from those of the Old World : Diplodus, Cladodus, Orodus ; Diplodus com- pressus Newb., Linton, Ohio; D. latus Newb., ibid.; D. gracilis Newb., ibid.; Petalodus, Ctenoptychius, Chomatodus ; Fig. 1102, Petalodus destructor N. & W., from Illinois ; 1104 a, 1104 &, Petrodus occidentalis N. & W., from Illinois, Indiana, etc.; 1103, fin-spine found associated with the scales of Petrodus occidentalis, and referred by F. H. Bradley to the same species. Cholodus, Peltodus, Calopodus, Ctenoptychius are other genera. Of fin- spines, there are Orthacanthus arcuatus Newb., Linton; Compsacanthus Icevis Newb., Linton; Drepanacanthus anceps N. & W., from Springfield, 111., and others. The genera of the Subcarboniferous are in part represented among the Carboniferous species, as Diplodus, Orodus, Cladodus ; Petalodus (Fig. 1102, P. destructor N. & W., 111.), Petrodus (Fig. 1104 a, b, P. occidentalis, N. & W., Ill, Ind., etc.), Ctenoptychius, Chomatodus, Deltodus, Pcecilodus, Xystrodus. Besides, there are 4 species of Agassizo- dus, all from the Coal-measures. Also fin-spines of the genera Compsacanthus, Drepana- canthus, etc. For figures and descriptions of fossil species the most important volumes are those of the Ohio Geological Report by Newberry, and those of the Illinois Report by Newberry and Worthen and St. John and Worthen. (6) Amphibians. Fig. 1109, Pelion Lyelli Wyman, Linton, Ohio ; Fig. 1108, Amphi- bamus grandiceps Cope, Morris, 111.; Fig. 1110, vertebrae and ribs from Linton, figured by Wyman, but not named, referred by Cope doubtingly to the snake-like Molgophis macrurus Cope. Baphetes planiceps Owen, from Pictou, N.S.; the specimen is a portion of the skull 7 inches broad. The genera Phlegethontia and Molgophis of Cope are referred to Dolicho- soma of Huxley by Fritsch. For descriptions and figures of the species of Ohio, see Geol. Rep., Pal. ii. ; of Nova Scotia, Dawson's Acad. GeoL, and its supplement of 1878, the latter containing also figures of Insects, Crustaceans, and Myriapods ; also Supplement of 1891, and later in the Trans. Roy. Soc. The Linton layer in Ohio is a local formation of cannel coal at the bottom of the Pittsburg coal-bed, indicating, as Newberry states, lake- like conditions during the progress of the layer. Twenty-three consecutive footprints of an Amphibian, Thenaropus heterodactylus, were found by A. T. King, near Westmoreland, Pa. , in a layer about 100' below the horizon of the Pittsburg coal ; the tracks of the hind-feet 5-toed, and of the fore-feet 4-toed, the former 5i inches long, and the latter 4} inches ; and the distance between the successive tracks 6 to 8 inches, and between the 2 lines about the same. Another species from the same region is the Chirotherium Reiteri of Moore. 2. PERMIAN PERIOD. On the Permian Flora of West Virginia, etc., see Fontaine and White, I.e.] contains 38 plates. The following are the Coal-measure species which continue, according to these authors, into the Permian or Upper Barren Measures of West Virginia and Pennsylvania : Calamites Suckovi, Sphenophyllum filiculme, Annularia longifolia, A. sphenophylloides, Neuropteris hirsuta, N. flexuosa, N. auriculata, N. cordata, Pecopteris arborescens, P. PALEOZOIC TIME CARBONIC. 693 Candolleana, P. pteroides, P. dentata, P. notata, P. oreopteridea, P. Miltoni, P. Plucke- neti, Goniopteris emarginata, G. elegans(?}, G. arguta(?}, Rhacophyllum lactuca, Sig- illaria Brardii. Of these species, all but Sphenophyllum filiculme, Neuropteris hirsuta and Pecopteris notata are also European Permian species. The genera Baiera and Callip- teridium commence in the Permian. Out of 107 species of plants in the Upper Barren Measures of West Virginia, 28 are European Permian species. The Red-beds of South Park, near Fairplay, Col. , have afforded Permian species of Walchia, Callipteris, Odontopteris, Sphenopteris, Ullmannia, etc. (Lesquereux, Bull. Mus. Comp. ZooL, viL, No. 8). On Amphibians and Reptiles of Texas and Illinois, Cope, Amer. Phil. Soc. for 1877 and several later years, and also Proc. Acad. N. 8., Philadelphia, Amer. Naturalist Bull., vi., Hayden Surv., 1881, and publications of Texas Geological Survey. FOREIGN. 1. SUBCAKBONIFEROUS AND CARBONIFEROUS PERIODS. ROCKS KINDS AND DISTRIBUTION. The rocks of the Subcarbonif erous and Carboniferous periods cover a very large area in the western half of Kussia, or the Continental Interior of Europe, much of the area of Great Britain and Ireland, a moderately large area on the borders of Belgium, France, and Prussia, and small areas in Spain, Italy, Austria, and some other parts of Europe. The beds of the Carboniferous period the period of the Coal-measures have their greatest thickness and largest amount of coal in the British Isles, and but little thickness and little coal in Eussia. There are workable coal-beds of this era, if the Permian be included, also in China, India, and Australia, but none, so so far as known, in South America, Africa, or Asiatic Russia. The proportion of coal-beds to area in different parts of Europe has been stated as follows : in France, y^- of the surface ; in Spain, -fa ; in Belgium, ^5-; in Great Britain, y 1 ^. But, while the area of the Coal-measures in Great Britain is about 12,000 square miles, it is in Spain, 4000; in France, about 2000 ; in Belgium, 518. The distribution of the areas in England is shown on the accompanying map. The cross-lined black areas are Subcarboniferous, and the black those of the Coal-measures. The principal regions of the latter are (1) the South Wales, 1000 square miles in area ; and, in nearly the same latitude, the Forest of Dean, west of the Severn, and the region about Bristol, east of the Severn, together 184 square miles ; (2) the small patches in central England, in Shropshire (Coalbrook Dale), Warwickshire, Leicestershire, and Staffordshire, 240 square miles ; (3) north of these, on the west, the great South Lancashire region, just east of Liverpool, with the basin of Flintshire on the Dee, the whole together, 220 square miles ; (4), to the eastward of the last, the large Derbyshire coal region, between Nottingham and Leeds, and adjoining Sheffield, 800 square miles ; (5) farther north on the west coast, in Cumber- land, about Whitehaven, 25 square miles ; (6) on the east coast, the great 694 HISTORICAL GEOLOGY. coal-field of Northumberland and Durham, about Newcastle, 796 square miles. In Scotland, the beds cover an area 100 miles long by 25 broad, lying in the depression between the Grampian range on the north and the Lammer- Fig. 1126, Geological map of England. The areas lined horizontally and numbered 1 are Silurio-Cambrian ; those lined vertically (2) Devonian ; those cross-lined (3) Subcarboniferous ; the black areas (4) Carboniferous ; the dotted areas (5) Permian ; those lined obliquely from right to left (6) Triassic, (7 a) Lias, (7 6) Oolyte, (8) Wealden, (9) Cretaceous ; those lined obliquely from left to right (10, 11) Tertiary. A is London ; B, Liverpool ; C, Manchester ; D, Newcastle. Ramsay. muirs on the south. The most of the workable coal-beds occur in the Sub- carboniferous. In Ireland, over its center and to the southwest, a large part of the surface rock is Subcarboniferous limestone. It is believed that the Coal- measures once covered this limestone. PALEOZOIC TIME CARBONIC. 695 The Subcarboniferous rocks of Great Britain include a limestone formation called often the " Mountain limestone," and also shales and sandstone. The limestone is the chief rock in southern England, where, near Bristol, it is 2000' thick and has shaly beds at base, the "Lower limestone shale." In Derbyshire, the limestone, 4000' in maximum thickness, is succeeded by a series of shales and sandstones with beds of limestone, called the Yore- dale group. This Yoredale group is 2300' thick in North Staffordshire, making a total thickness of 6300'; it is 4500' thick in Lancashire. In Wales the thickness of the lime- stone is but 500', and in Anglesey, 200' to 500'. In Scotland, the Subcarboniferous rocks are mainly fragmental, and are called the Calciferous limestone group. In southwestern Ireland, the limestone has a thickness, in Limerick, of 3600'. But in northern Ireland, the fragmental beds increase in amount and thereby become similar to those of Scotland, as if they were their continuation. In Northumberland, in northern England, fragmental beds greatly predominate ; the total maximum thickness is 8000', and of this, only 20' to 50' is limestone ; they have received a distinct name, that of the Bernician group, because they are so unlike the rest and without any natural subdivision ; and those of the valley of the Tweed and the vicinity have been termed the Tuedian group. The Carboniferous limestone of the Lake District and Yorkshire was called the " Scar limestone" by Sedgwick, from the topographic features, or "scars" produced by the rock. It makes a strong impression on the scenery of many parts of England. " Massive beds of it," says Prestwich, " rising from beneath the Mesozoic strata in the neighborhood of Frome and Wells, constitute the main range of the Mendips. At Clifton it is traversed by the gorge of the Avon. A few miles to the north the limestone passes under the great plains of central England to reappear in the picturesque hills of Derbyshire, the bluffs of Matlock, the scarps of Dovedale, and the high ridges of Buxton. In Yorkshire the limestone hills, which rise to heights of 2000' to 2500' in the Pennine chain, are intersected by the many beautiful dales so characteristic of that district. The prevailing cold gray color of the limestone, the frequency of bared surfaces, and the innumerable caves famous for their magnitude and their stalactites, or as the dens of Pleistocene Mammals render the rocks easily recognizable, and contribute greatly to their scenic effects." The limestone contains much chert. Hinde has shown that the chert abounds in sponge-spicules ; and Carter has observed facts illustrating the passage by solution of the spicules into chert. The beds of the Coal-measures in England have generally at bottom the Millstone grit, answering to the Pottsville conglomerate of Pennsylvania. The thickness is 400 to 1000 feet in South Wales, about 1200 feet in the Bristol coal-field, 3000 to 5000 feet in the Lancashire region ; but in the north of England only 500 feet, and in Scotland it is barely recognizable. The Coal-measures in South Wales have a thickness of 7000 to 12,000 feet, and include more than 100 coal-beds, 120 feet in total thickness, 70 of which are worked. While the coal is bituminous near Swansea, it becomes anthra- cite to the west and north. In the Eorest of Dean, the thickness of the beds is 2400 feet, and they comprise at least 23 coal-beds ; while in the Bristol coal-field, on the other side of the Severn, there are 5090 feet of Coal-measures, with 87 coal-beds. In the south Lancashire coal region, which reaches nearly to Liverpool, the Coal-measures are stated to have a thickness of 7200 to 8000 feet, and to include more than 40 beds of coal over one foot in thickness, and in north 696 HISTORICAL GEOLOGY. Staffordshire the thickness is 8000 feet. But to the northward, in Derby- shire, the thickness is about 2500 feet, and in Northumberland and Durham, and in Scotland 2000 feet. The coal-beds, as elsewhere, usually rest on a bed of fire clay containing rootlets. In the Newcastle region, the Coal-meas- ures are about 2000 feet thick, and include about 60 feet of coal : the beds afford about a fourth of the coal of England. The Lancashire area and the Cumberland farther north lie on the west side of an anticlinal ridge, mostly of Subcarboniferous and Lower Carbonif- erous rocks, called the Pennine chain, in some points 2000 feet high, which extends north to the Cheviot Hills, between England and Scotland. The Derbyshire and Newcastle areas are to the east of this anticlinal. Prestwich observes, with regard to a parallelism in the several coal-beds, between the different British coal-fields, and between these and European coal-fields, that, while this is not to be looked for, some general relations may be made out. The great dividing mass of rock, 2000 to 3000 feet thick, called Pennant, exists in both the Welsh and Bristol coal-fields ; and the total thickness is not very different in the two about 10,500 feet in one and 8500 in the other, with 76 coal-beds in Wales, and 55 in Somerset. In the Hainault (or Mons and Charleroi) basin, the measures are 9400 feet thick, with 100 beds of coal ; in the Liege basin, 7600 feet, with 85 beds ; in West- phalia, 7200 feet, with 117 beds. In Belgium, in the region of the Meuse, the Carboniferous limestone has a thickness of nearly 2500', and includes at top the "Limestone of Vis6" ; 800' below the top, the " Dolomite of Namur " ; and 2000' below the top, the " Limestone of Dinant." The wide-spread Subcarboniferous formation in Kussia is chiefly limestone. To the eastward, at the west base of the Urals, there is one wide north- and-south belt, and another to the westward extending from the Arctic Sea, in 662 N., to 54 N. Near Moscow the formation was reached by boring through the Jurassic and underlying beds. The Carboniferous limestone has been found by Richthofen to underlie a large coal region in China, and to be marked by Fusulina and other fossils of the European Subcar- boniferous beds. The Belgian Coal-measures of Liege and Mons extend 80 miles along the northern flanks of the Ardennes, and have numerous coal-beds, the thickest 3'. The principal coal basin of Germany is that of Saarbriick in the Rhenish provinces, 900 square miles in area. In a thickness of Coal-measures of nearly 20,000', it contains 82 workable beds, included mainly in the lower 9000'. Another area is that of Westphalia. Silesia, in a coal region 16 miles square, has one coal-bed 50' thick. Some anthracite-bearing beds occur in the western Alps among schistose crystalline rocks, but none of economical value. The chief Austrian basin is in Bohemia at Pilsen. Russia has valuable coal-beds at Donetz on the north shore of the Azof. In China, plants of Carboniferous age have been obtained, to the north in the peninsula of Manchuria, where coal-beds are worked, and also in the provinces of Shansi, Hunan, Pe-chi-li, and others (Richthoferi 1 s China, vols. ii. and iv.). Carboniferous Coal-measures occur also in Japan and Borneo. In the Arctic seas, Spitzbergen has a coal formation well developed, but no beds of coal. The Coal-measures are 1000' to 2000' thick in Robert's valley, with many coal plants in the shales ; and the Subcarboniferous limestone and other rocks (which probably pass down into Devonian), and afford fossil Corals, Crinoids, and Brachiopods related to European and American species, besides plants ; and the chert has been reported by Hinde to be full of Sponge-spicules. PALEOZOIC TIME CARBONIC. 697 2. PERMIAN PERIOD. On the map of England (Fig. 1126) a border of Permian is represented along the east side of the Newcastle Carboniferous area, and also adjoining other coal areas excepting that of South Wales. (The areas are marked with dots on a white ground, and numbered 5.) A small area occurs in Ireland, about the Lough of Belfast. The rocks are red sandstone and marlytes, along with Magnesian limestone. Before their relations were correctly made out, they were included, along with part of the Triassic, under the name "New Red Sandstone." In Durham, northeastern England, there is (1) a Lower Red sandstone, 200 feet thick ; then (2) a, 60 feet of marl-slate ; b, two strata of Magnesian limestone, the lower 500, and the upper 100 feet thick, separated by 200 feet of gypseous marlyte, and overlaid by 100 feet of the same. The Magnesian and other limestones disappear to the south, near Nottingham. In north- western England, the Lower Permian includes 3000 feet of marlytes and sandstones; the Middle, only 10 to 30 feet of Magnesian limestone; the Upper, 600 feet, similar to the Lower. There are detached Permian areas in Dumfriesshire, Ayrshire, etc., in Scotland. In European Russia, Permian strata cover a region more than twice as large as all France; it includes the greater part of the governments of Perm, Orenburg, Kazan, Nizhni Novgorod, Yaroslavl, Kostroma, Viatka, and Vologda. The beds are sandstones, shales, marlytes, and dolomitic lime- stone, and contain an occasional thin seam of coal. The deposits are flanked and underlaid on nearly all sides by different members of the Carboniferous formation containing comparatively little coal. In central Germany small areas occur, from southern Saxony, along the Erzgebirge, over the adjoining small German states, west to Hesse Cassel, and north to the Harz Mountains and Hanover. Within this area, Mans- feld is one noted locality, situated in Prussian Saxony, not far from Eisleben ; another is on the southwest borders of the Thuringian forest (Thuringer- wald) in Saxe-Gotha, a line which is continued to the northwest, by Eise- nach, toward Miinden in southern Germany. In Thuringia and Saxony, the subdivisions of the rocks, beginning below, are (1) the Eothliegende, or Red beds, consisting of red sandstone, and barren of copper ores ; near the town of Eisenach, about 4000 feet thick ; (2) The Zechstein formation, or Mag- nesian limestone, consisting of (a) the Lower Zechstein, a gray, earthy lime- stone, overlying the Kupferschiefer, or copper-bearing shales, and the still lower Weissliegende or Graulieyende, or white or gray beds ; (6) the Mid- dle Zechstein, Magnesian limestone, called the JRauchwacke and Rauhkalk ; (c) the Upper Zechstein, or the Plattendolomit, and including the impure fetid limestone called Stinkstein. The lower part of the Lower Permian of England includes, in some places, beds of coarse conglomerate, containing angular masses of rock of great size. 698 HISTORICAL GEOLOGY. Eamsay attributes the transportation of the blocks to floating ice. Bowlders in beds of great thickness and coarseness, glacial-like, with many of the bowlders scratched, occur toward the bottom of the Talchir group of India, regarded as Lower Permian; in equivalent beds of the Salt Eange of northern India ; in the related Ecca beds of South Africa, below the Karoo beds ; in beds beneath the Glossopteris Coal-measures of eastern Australia, and also other beds overlying the same, called the Hawkesbury sandstone ; and also in Victoria and Queensland. In New Zealand similar bowlder beds are referred by Dr. Hector to the Trias. The above facts have led some geologists to the conclusion that over India, Australia, and South Africa, there were glacial conditions in the course of the Permian era a time when Europe and America were under luxuriant vegetation. The Permian has much extent also in Bohemia and Moravia. On both sides of the Alps are red sandstones underneath Triassic beds, which are referred to the Permian. In France, its beds lie at the base of the Vosges, whence they extend into the Black Forest ; at Autun, the thickness is 3000'; the rocks are, as usual elsewhere, sandstone, marlytes, and conglomerates. In the Indian peninsula, according to the report of W. T. Blanford, Director of the Geological Survey, the Damuda series in western Bengal, with its valuable coal-beds, and also the underlying Talchir beds, called together the Lower Gondwana series, cor- respond to the upper part of the Carboniferous and the Permian, excepting the Panchet group at the top, which is Triassic. The beds have a thickness of 6000' to 11,000', and the coal-beds an aggregate thickness of 175' or more. A 6-inch bed of coal occurs in the Talchir group. The Coal-measures of Karharbari overlie the Talchir beds. The Dainuda beds contain species of Glossopteris (Glossopteris Browniana most abundant), Alethopteris, Tceniopteris, Sphenopteris, Sphenophyllum, Gangamopteris, Sagenopteris, besides Pterophyllum and other Cycads, Voltzia heterophylla, Vertebraria, etc. The Rajmahal group, of the Upper Gondwana series, is supposed from its fossil plants to be Lower Jurassic, Cycads being the prevailing species, as much so as Glossopteris and Vertebraria are in the Damiidas. In Australia, the coal formation, with excellent coal, occurs in Illawarra, also on Hunter's River, and elsewhere ; and, from the fossil plants, the absence of Lepidodendrids and Sigillarids, and the abundance of Glossopteris, with species of Sphenopteris, Verte- braria, etc. (the range of species much resembling that of the Damiida beds), together with the occurrence, immediately below, of shales containing Carboniferous Brachiopods, Conularise, etc., and a heterocercal Ganoid, Urosthenes australis D., the series was referred by the author (in his Wilkes Exped. Geol. Rep., 1849) to the " Upper Carboniferous or partly Lower Permian." It is made the equivalent of the Damiida series by Blanford. W. B. Clarke mentions the occurrence of leaves of Glossopteris in the Coal-measures, having a length of about 2', and of the frond of a Sphenopteris, which when entire must have measured 5' in length. The Coal-measures are about 480' thick, and contain 11 seams of coal. D. Stur has shown that in Germany and Austria the Permian is characterized by related species of Tceniopteris, Pterophyllum and Sagenopteris, closely representing those of India and Australia. The Lower coal-beds occur in Australia also, below the above-mentioned beds, in the Hunter's River region, and westward through Durham, Brisbane, etc., which contain species of Lepidodendron, Sigillaria, Knorria, Cyclopteris, etc. Above the Upper Coal-measures in Australia comes the wide-spread Hawkesbury sandstone and the PALEOZOIC TIME CARBONIC. Wianamatta shale, with Palceoniscus antipodeusTZg., but without Glossopteris and other lower species ; the beds are probably Triassic and Jurassic. Jurassic Ganoids of the genera Coccolepis, Leptolepis, and others, have been reported by A. Smith Woodward (1890), from specimens discovered by C. S. Wilkinson and R. Etheridge, Jr. Both the Glossopteris and Lepidodendron floras occur in Victoria, and the former in Queensland. South Africa has a coast border of gneiss and other schists, and inside of it a belt of Paleozoic rocks with Carboniferous at top (in Table Mountain, etc.). The great interior region thus bordered is occupied by the " Karoo formation" from Table Mountain north- ward over Orange Free State and Basutoland, reaching the coast only to the southeast in Caffraria. It includes (1) the Ecca beds (with the Dwyka bowlder bed [glacial ?] in the lower part), which contain Glossopteris, etc., and are regarded as Permian, or of the age of the Talchir and Damiida beds of India ; (2) the Middle Karoo, or Beaufort beds, Permian or Triassic ; and (3) the Upper Karoo or Stormberg beds, supposed to be Tri- assic. For a colored geological map by A. Schenk, see Peterm. Mittheil., 1888. LIFE OF THE SUBCARBONIFEROUS AND CARBONIFEROUS PERIODS. PLANTS. The same genera of plants, with few exceptions, are repre- sented among the European coal-beds as occur in America ; and about a third of the American species are found also in Europe. In this respect the vegetable and animal kingdoms are in strong contrast; for the species of animals common to the two continents have always been few. The number of species in the European flora of the Carboniferous (the British included) is stated to be nearly 1400, while North America, so far as described, including the Carboniferous and Subcarboniferous periods, has afforded, as enumerated by Les- quereux in the concluding part of his Pennsylvania Report of 1884, excluding fruits, about 625 species, and including fruits, nearly 800. Over 200 species of the 625 exist also in Europe. The number of species of the several genera common to the two continents is given by Lesquereux as follows : Calamites, 11 ; Aster ophyllites, 6 ; Annularia, 6 ; Sphenophyllum, 8 ; Macrostachya, 1 ; Neuropteris, 17; Odontopteris, 5; Dictyopteris, 3; Callipteridium, 3; Alethopteris, 6; Pseudopecopteris, 16; Pecopteris, 29; Oligocarpia, 1 (O. GutUeri) ; Sphenopteris, 20 ; Eremopteris, 2 ; Ehacophyllum, 7 ; Stemmatopteris, 1 ; Caulopteris, I ; Megaphyton, 1 ; Lepidodendron, 14 ; Ulodendron, 4 ; Knorria, 3 ; Halonia, 3 ; Cyclostigma, I ; Lepido- phloios, 3 ; Lepidophyllum, 1 ; Sigillaria, 25 ; Syringodendron, 3 ; Stigmaria, 1 ; Cordaites, 1. The flora of the Subcarboniferous of Europe includes species of Archceopteris, Sphenopteris, Lepidodendron (as L. Veltheimanum, L. squamosum}-, Knorria (K. imbri- cata, K. acicularis) ; Bornia transitions, Asterophyllites elegans, Stigmaria ficoides. The flora of the Middle and Lower coal is much like the American. The Upper coal contains Sigillarise, but rarely a Lepidodendron ; species of Calamites, Calamodendron, and Annu- laria are common, the Annularia becoming rare above ; species also of Pecopteris, Callip- teris, Neuropteris, and Odontopteris, are common, but not of Sphenopteris. Cordaites also is common. With these occur species of true Cycads, and of Walchia ( W. piniformis), a Conifer. Among the Diatoms observed by Castracani in the coal of England, the following 8 species are now living: Fragillaria Harrisoni Sm., Epithemia gibba Ehr., Sphenella glacialis Ktz. , Gomphonema capitatum Ehr. , Nitschea curvula Ktz., Cymbella Scotica Tm. f Synedra vitrea Ktz., Diatoma vulgare Bpry. 700' HISTORICAL GEOLOGY. ANIMALS. Khizopods are of many kinds. Fusulina cylindrica (Fig. 1069) occurs in the beds from the Subcarboniferous to the Permian in Europe and Asia; and F. Japonica is a species from Japan described by Gumbel. The Subcarboniferous limestone in northern England contains abundantly the arenaceous form, Saccammina Carteri Brady, occurring as groups of single isolated spheroids, or occasionally of strings of them, averag- 1127-1132. 1129. 1128. 1127. 1133. BBAOHIOPODS. Fig. 1127, Orthothetes (Streptorhynchus) crenistria; 1128, Athyris lamellosa; 1129, Tere- bratula (Dielasma) hastata ; 1130, Productus longispinus ; 1181, Spirifer glaber ; 1132, Nautilus (Trema- todiscus) Konincki. Figs. 1127-1130, de Koninck ; 1131, Davidson ; 1182, D'Orbigny. ing one eighth of an inch, though rarely one fifth of an inch, and making the rock to look as if oolitic. It is very abundant in the "four-fathom" lime- stone of the English Subcarboniferous. The Subcarboniferous limestone, like the American, is noted for its Crinoids ; its many Brachiopods of the genera Productus, Chonetes, and Rhynchonella ; its Corals of the genus Lithostrotion, Cyathophyllum, Zaphrentis, of which only the first is found in the Coal-measures ; its many Gastropods of the genera Loxonema, Plevrotomaria, Euomphalus, Murchisonia, Bellerophon , Macro- cheilus, etc. ; its many Goniatites, Nautili) Orthocerata, and Discites; the limited variety of Trilobites; for Ganoids, Sela- semi- cn i ans > an d Amphibians among Vertebrates, nifera. De Some of the common Subcarboniferous Brachiopods are rep- oninck< resented in Figs. 1127 to 1132. Trilobites occur only of the three Carboniferous genera, Phillipsia, Ghriffithides, and Brachymetopus. A species of Phillipsia is represented in Fig. 1133, P. seminifera Morr. PALEOZOIC TIME CARBONIC. 701 The Subcarboniferous beds of Great Britain have yielded 16 species, but the Coal-measures none. The foreign Goal-measures have afforded also Eurypterids; Limulids, as species of Prestwichia, Fig. 1136, and Belinurus; Crustaceans, of the higher tribe of Macra- rans > as Fig. 1134, Anthraco- palcemon, Fig. 1135, Gampso- nyx, from Saar- bruck ; Scorpi- ons, one of which, from Bohemia, Cydophthalmus senior of Corda, is shown in Fig. 1137 ; also Spiders of the genera Architarbus, Anthracomartus, Geralinura, etc. ; Myriapods of the genera Euphoberia, Xylobius, Acantherpestes, Archiulus. There were also Insects of many kinds. The Orthopte- roids included Cockroaches, of the genera EtoUattina, Fig. 1139, Anthraco- Uattina, Gerablattina, and others; but few kinds compared with North Anthracopalaemon Salteri. Salter. 1135. 1135-1139. 1138. 1139. CRUSTACEAN. Fig. 1135, Gampsonyx fimbriatus. LIMULID. Fig. 1136, Prestwichia rotundata (x |). SCOB- PION. Fig. 1137, Cydophthalmus senior. INSECTS. Fig. 1138, Dictyoneura anthracophila ; 1139, Etoblat- tina primaeva. Figs. 1135, 1137, 1138, Brown ; 1136, Murchison ; 1139, Vogt. America; Protophasmids (or species related to the modern "Leaf-insects" and "Walking-sticks ") of several genera, as Titanophasma Fayoli of Brong- 702 HISTORICAL GEOLOGY. niart, represented in Fig. 1140, only ^ the natural size, (which has, as Brongniart states, the wings of a Neuropter with many characteristics of an Orthopter,) Dictyoneura anthracophila, Fig. 1138 ; D. Monyi, having wings a foot long, Archceoptilus ingens Scudder, of the British Coal-measures, having a spread of wing of about 14 inches ; also forerunners of the " Dragon-flies," one of them having a spread of wing much exceeding two feet. Among the 1140. OKTHOPTEB. Titanophasma Fayoli (x J), with the outline in part of the rock. Brongniart. ITeuropteroids, the Lithomantis carbonaria of Scotland was probably nearly six inches in spread of wing. Moreover, Beetles, or Coleopteroids, have been reported from the Coal-measures of Silesia, and Hemipters from several localities. There were also the inferior wingless species, the Thysanura (common existing genera of which are Lepisma or Silver-moth, and Podura). The gigantic Titanophasma Fayoli, Dictyoneura Monyi., and the fore- runner of the Dragon-flies, as well as the small Thysanurce, were from the Coal-measures of Commentry, in central France, a locality that has afforded C. Brongniart for description a wonderful variety and number of species. Eemains of Subcarboniferous Fishes are common in Europe and Britain ; the British Islands alone have afforded 150 species. Among them are Coch- liodus contortus Ag., Fig. 1141 ; Cladodus marginatus Ag. ; Ctenacanthus major, Fig. 1142, one broken specimen of which is 141 inches long. Another broken spine, de- scribed by Agassiz, Oracanthus Milleri, is 9 inches long and 3 inches wide at base. Fig. 1143 represents a restoration of the Pleuracan- thus (=Diplodus Ag.) Oaudryi of Brongniart, from the Carboniferous rocks of France a Shark having a terminal mouth. The Fishes of the Coal-measures include Selachians also of the genera Ctenodus, Ctenoptychius, Helodus, Cladodus, Orodus, etc., which are also mostly Subcarboniferous. The most common Coal-measure genera of Ganoids are Palceoniscus, Amblypterus, Holoptychius, and Megalichthys. 1141. Cochliodus contortus (x J). PALEOZOIC TIME CARBON 1C. 703 The Amphibians have nearly the same range of characters as the American. There are Loxomma Allmanni Hux., from Edinburgh, the skull 10 inches wide and 14 inches long, and the teeth with cutting edges ; Anthracosaurus 1142. 1143. Fig. 1142, part of a spine of Ctenacanthus major Ag. ; 1148, restoration of Pleuracanthus Gaudryi Brongniart. Russelli Hux., Lanarkshire ; Parabatrachus Colei Owen, British Coal-meas- ures ; Anthracerpeton crassosteum Owen, Glamorganshire ; Archegosaurus Decheni Goldfuss, Saarbruck, 3 feet long; A. minor Meyer, Saarbruck; besides various snake-like and other species. 1. Brachiopods. Some of the characteristic species, besides those figured, are : Pro- ductus scabnculus Sow. ; Spirifer speciosus Br., S. cuspidatus Sow., 8. disjunctus Sow. ; Chonetes Dalmanianus Kon. ; Orthis Michelini Morr. 2. Limulids. Fig. 1136, Prestwichia rotundata Woodw., Coalbrook Dale; P. an- thrax Woodw., Coalbrook Dale; Belinurus trilobitoides Woodw., Ireland, Coalbrook Dale ; B. Eegince Baily, Ireland ; B. arcuatus Baily, Ireland. 3. Crustaceans. Fig. 1135, Gampsonyx fimbriatus Jordan, a Schizopod; 1134, An- thracopalcemon Salteri, Lanarkshire, A. dubius S., Coalbrook Dale, A. Grossarti S. Lanarkshire ; the broad flattened thorax indicates a nearer relation to ^Eglea and Galathea than to Palcemon. Pygocephalus Couperi Hux. , a Schizopod, Manchester, England. 4. Myriapods. Euphoberia Brownii Woodw., Glasgow, E. anthrax Woodw., Coal- brook Dale, XyloUus sigillarice Dn. , Glasgow and Huddersfield. 6. Arachnids. Fig. 1137, Cyclophthalmus senior Corda, Chomle, Bohemia ; Eophry- nus Prestwichii Buckl., Dudley ; Geralinura Bohemica Kusta ; Architarbus subovalis Woodw., Lancashire, very near the Illinois species (page 691) ; Protolycosa anthraco- phila K., Silesia ; Anthracomartus Volkelianus Kranch, Silesia. 704 HISTORICAL GEOLOGY 6. Insects. Dictyoneura anthracophila Goldb., from Saarbruck; D. Humboldtiana Goldb., ib. ; Polioptenus elegans Goldb., ib. ; Etoblattina primceva Goldb., ib. ; Gryllacris lithanthraca Goldb. (Locust), ib. ; Corydalis Brongniarti Mant., Coalbrook Dale. 7. Amphibians. The Amphibians included Apateon pedestris H. v. Meyer, Munster- appel ; Urocordylus Wandesfordii Hux., Kilkenny, the tail with 75 vertebrae ; Ophiderpeton Brownriggii Hux., Kilkenny, limbless, snake- like and 3' long ; Dolichosoma longissimum Fritsch, from Ireland, probably about 3' long and much like the whip-snake ; species of Dendrophis, and of other genera. The following foreign Coal-measure Brachiopods occur also in the American beds : Athyris subtilita, Spirifer lineatus Martin, Productus longispinus Sow., P. latissimus Sow., P. punctatus Martin, P. scabriculus Martin, P. costatus Sow., Orthothetes (Streptorhynchus) umbraculus v. Buch, Devonian to Permian. The Arctic Spitzbergen Coal-measure plants include species of Lepidodendron, Stig- maria, Sphenophyllum, Aster ophyllites, Sphenopteris, Cordaites; and the Subcarboniferous of Bear Island (30m. south), the European species Calamites radiatus, Lepidodendron Veltheimanum, Knorria imbricata, K. acicularis, Cyclostigma Kiltorkense, Palozopteris (Archceopteris} Bcemeriana, Sphenopteris Schimperi, Cardiopteris frondosa, C. polymor- pha, etc., made a basis by Heer for his Ursa stage, but supposed by Dawson to include some Devonian species. The beds of Spitzbergen contain the Permian species, Productus horridus, specimens twice the size of those of the European Permian, P. Cancrini Vern., P. LeplayiVeTn.j Camarophoria Humbletonensis Howse, Strophalosia lamellosa Gein. ; Carboniferous species of Euomphalus, Cyathophyllum, Syringopora, Chetetes ; and the Subcarboniferous includes a Cyathophyllum limestone in which there are 4 species of Corals, 2 of Crinoids, and Spirifer incrassatus, Terebratula fusiformis, and other Russian Brachiopods. LIFE OF THE PERMIAN PERIOD. PLANTS. The Permian plants include no Lepidodendrids, a few Sigilla- rids; Ferns of the genera Neuropteris, Sphenopteris, Pecopteris, Alethopteris, Tceniopteris, Sagenopteris, Glossopteris, and others ; also Calamites, Annularia, Asterophyllites ; Cycads and Conifers. The Conifers included species of Dadoxylon, Pinites, Ullmannia, etc. The genus Walchia, Fig. 1147, Walchia piniformis Sternberg, characterized by lax and short spreading leaves, began near the close of the Carboniferous period, but is most numerous in species during the Permian. Tree-ferns of the genus Psaronius were common, as in the Upper Coal-measures. Fig. 1144 is the pinnule or branchlet of a frond of Neuropteris Loschii, a species common to the Permian and Coal-measures ; 1145, showing the vena- tion. Fig. 1146, Annularia carinata Sternberg ; in 1146, only the first joint and its whorl are shown, of natural size ; in 1146 a, a branch is shown (of reduced size), consisting of its several joints and whorls, but the natural termination is wanting. The figures are from the work of Geinitz and Gutbier on the " Dyas " of Saxony. The American Permian species that are common to the Permian formation of Europe, according to Fontaine and White, Pennsylvania Report (1880), are, for the several genera, as follows: Equisetites rugosus, Calamites Suckovi, Sphenophyllum longifolium, Annularia carinata, A. longifolia, A. sphenophylloides, A. radiata, A. minuta, Neuropteris flexuosa, N. auriculata, N. cordata, Odontopteris obtnsiloba, Callipteris conferta ; Pecopteris ar- PALEOZOIC TIME CARBONIC. 705 borescens, P. Candolleana, P. oreopte.ridia, P. pennceformis, P. latifolia, P. Miltoni, P. dentata, P. pteroides, P. Pluckeneti, P. German, Goniopteris emarginata, G. elegans, Alethopteris gigas ; Rhacophyllum filiciforme, R. lactuca, Sigillaria Brardii. In addition, Tceniopteris Lescuriana is near T. multinervis, T. Newberryiana near T. vittata ; Cau- lopteris elliptica is allied to C. peltigera, C. gigantea to C. microdiscus, and Baiera Virginiana to B. digitata. 1145. 1144-1147. 1144 1147. Figs. 1144, 1145, Neuropteris Loschii ; 1146, 1146 a, Annularia carinata ; 1147, Walchia piniformis. All Geinitz. ANIMALS. Corals of the Cyathophyllum family, Brachiopods of the genera Productus, Spirifer, and Orthis, Pteropods of the genus Conularia, Cephalopods of the genus Orthoceras, and Ganoid fishes with vertebrated tails, give a Paleozoic character to the Fauna. But there are many new tribes : among these, the most prominent is that of Eeptiles. This transition character is apparent also in the number of old animal types as well as vegetable that here nearly or quite fade out, for it is the period of the last of the species of Productus, Orthis, Murchisonia; nearly the last of the extensive tribe of Cyathophylloid Corals, which made coral reefs of far greater extent than those of modern seas ; nearly the last of the extreme vertebrate-tailed (heterocercal) Ganoids. 1148. Paleeomscus Freieslebeni (xj). Murchison. 1. Fishes. Ganoids occur of the genera Palceoniscus, Fig. 1148; Platyso- mus, Acrolepis, Pygopterus, Ccelacanthus ; genera that are also Carboniferous. The figure illustrates the heterocercal feature of the species. There were also Cochliodont and Petalodont Sharks. DANA'S MANUAL 45 706 HISTORICAL GEOLOGY* 2. Amphibians. A species of Dasyceps, D. Bucklandi, occurs at Durham, England, and others of Branchiosaurus, Hylonomus, Ophiderpeton, etc., in European beds. 3. Reptiles. The Reptiles of the foreign Permian, like those of America, are in part Rhynchocephalians. The earliest genus, Palceohatteria of Cred- ner (1888) is from the Middle Permian (Rothliegende) of Saxony. A skull from one of Credner's figures is shown in Fig. 1150. The palatine bone has 1149. 1149-1152. 1161. Fi, REPTILES. Fig. 1149, Proterosaurus Speneri; 1150, Palaeohatteria longicaudata ; 1151, ankle bones (t, astraga- lus, ft, calcaneum, I to V, metatarsals, with T, tibia, and Fi, fibula); 1152, pelvic bones (pu, pubis ; il, ilium ; is, ischium ; with/, femur). Fig. 1149, von Meyer; 1150-1152, Credner, '88. teeth, and also the vomer, as common in Amphibians. The close relations to the New Zealand Hatteria are pointed out by Credner. The beak-like form of the anterior part of the head, to which the name Rhynchocephalian refers, is absent in this early species of the group. Proterosaurus (Fig. 1149) is a related but more lizard-like form from the Upper Permian of Thuringia. With the Palseohatteria occurs also (Credner, 1889) a related Reptile, the Cadaliosaurus. Like Mesosaurus (Stereosternum) , these Permian Reptiles PALEOZOIC TIME t CARBONIC. TOT represent the most generalized type of Reptiles, the five tarsal bones of the Palaeohatteria (1 to 5) with which the five metatarsals (i, n, in, iv, v) were articulated are shown in Fig. 1151, in which T, Fi are parts of the tibia and fibula. Other Reptiles are the Anomodonts and Theromores. The former have large tusks in the jaws, and no other teeth; they include the genus Dicynodon of Owen, which has species in the Permian Beaufort beds of South Africa, and also in the overlying Triassic beds. 1. Echinoderms. Crinoids near Cyathocrinus ; Echinoderms of the genus Archceo- cidaris. 2. Molluscoids . Brachiopods. Spirifer alatus Schloth. , England, Lower Zechstein in Saxony some specimens 2| inches broad ; Spiriferina cristata Dav., Zechstein, Germany; Productus horridus Sow., England, Germany, characteristic particularly of the Lower Zechstein, and occuring also in the Kupferschiefer ; Strophalosia excavata Gein., England, Germany, S. Goldfussi, ibid. ; the species of the genera Productus and Strophalosia are exceedingly abundant in individuals; Camarophoria Schlotheimi von Buch, Russia, Germany, England ; C. superstes, Russia. 3. Mollusks. (a) Lamellibranchs. Pseudomonotis speluncaria Beyr., England, Rus- sia, Germany, in the Lower Zechstein ; Clidophorus Pallasi Gein., Russia, Germany ; My- alina squamosa Sedg., Russia, England ; Avicula Kazanensis Vern., Russia ; Bakewellia antiqua King, England, Russia, Germany ; Schizodus dubius M., common in England, Germany, Russia ; S. Schlotheimi Gein., S. obscurus Sow., and S. truncatus King. The genus Schizodus is of the same family with Trigonia, a characteristic genus in the Rep- tilian age ; it commenced in the Devonian and ends with the Permian. (6) Gastropods are rare fossils in the Permian. There are a few species of Murchi- sonia, Pleurotomaria, and Straparollus, Paleozoic genera, and of Dentalium, Natica, Turbo, etc. (c) Pteropods occur of the genera Theca and Conularia. (d) Cephalopods existed, and among them two or three species of Orthoceras and Nautilus. 4*. Crustaceans. No Trilobites are known. Ostracoids are common. Under Tetra- decapods, the Amphipod, Prosoponiscus problematicus Schloth., Durham, England. Under Decapods, besides Macrurans, there is reported a Crab or Brachyuran, from the Permian, by von Schauroth, who named it Hemitrochiscus paradoxus. It is | of an inch long. Whether a true Crab or not is doubtful. 5. Vertebrates. Fishes. Palceoniscus Freieslebeni Agassiz is common in the Kup- ferschiefer, and is found also in the Coal-measures in England, at Ardwick. Other species are : Palceoniscus elegans Sedgw., P. comptus Ag., Platysomus macrurus Ag., PL gibbosus Bl., Acrolepis Sedgwickii Ag., Pygopterus mandibularis Ag., Ccelacanthus granulatus Ag., etc. Janassa bituminosa Miinst. and Wodnika striatula Mtinst. are species of Cestraciont sharks from the Kupferschiefer. The Paleozoic character of the life of the Permian, as already shown, is strongly marked. Geinitz observes, further, that the Terebratula (Dielasma) elongata Schloth. of the Zechstein approaches a Devonian form ; Camarophoria Schlotheimi Kg. (Zechstein) is near the Carboniferous C. crumena Mart. ; Spirifer Clannyanus Dav. (Zechstein), near the Carboniferous S. Urii ; Spiriferina cristata, near the Carboniferous S. octoplicata. The genus Schizodus ends with the Permian, as well as Orthis, Camarophoria, Productus, and Strophalosia. 708 HISTORICAL GEOLOGY. GEOLOGICAL AND GEOGRAPHICAL CHANGES DURING THE PROGRESS OF THE COAL-MEASURES. The beds of the Coal-measures vary in kind of rock between shales, sand- stones, conglomerates, and limestones, clay beds, iron ore beds, and coal-beds ; and differ in conditions of origin, between those of salt water, brackish water, and fresh water. Moreover, the beds bear evidence of the changes in water level that took place during the progress of the long series. In the various regions, the clayey beds beneath the coal evince that they were usually of marsh or fresh-water origin, like the coal-beds, by the absence of marine relics, and the presence of roots and sometimes of stumps of the trees that grew in the clay as their soil. In Nova Scotia, where deposits were made during the era to a thickness of 13,000 feet, the beds of the Subcarboniferous are partly marine, tut the Coal-measures and Permian are mainly of brackish or fresh- water origin ; for only one bed has been found to contain marine fossils. This region was a wide basin in the Acadian trough, at the mouth of the St. Lawrence Eiver. Specimens of the Pupa or land-snail, described by Dawson (page 676), occur in an under-clay more than 1200 feet below the level of the stump in which the species was first discovered ; and in this interval there are 21 coal-seams, showing, as Dawson observes, that the species existed during the growth and burial of at least 21 forests. The oscillations in water level, indicated by the alternations in the deposits, were slow in progress ; movement by the few inches a century accords best with the facts. When under verdure, the surface must have lain for a long period almost without motion ; for only a very small change of level would have let in salt water to extinguish the life of the forests and jungles, or have so raised the land as to dry up its lakes and marshes. Hence the grand feature of the period was its prolonged eras of quiet, with the land little above the sea limit. Again, for the making of shales or sand- stones, the continent may have rested long near the water's surface, just swept by the waves and currents, subsiding with extreme slowness, so as to make thick deposits without letting in the sea. It may have been long a region of barren marshes, and, in this condition, have received its iron-ore deposits, as now marshes become occupied by bog-ores. It must have been long in somewhat deeper waters, and covered with a luxuriance of marine life, in order to have received its beds of limestone holding marine fossils. Again the land slowly emerged from the waters, and the old vegetation spread rapidly across the great plains, commencing a new era of coal-making vegetable debris ; or the escape was only partial, and coal-plants took possession of one part, and made limited coal-deposits, while the sea still held the rest beneath it. Uniformity in oscillations of level, through so great an area, is not probable ; and therefore the farmer continuity of a single coal-bed through the East and West requires strong proof to be admitted. Such alternations of verdure and rock depositions occurred also during PALEOZOIC TIME CARBONIC. 709 the Subcarboniferous and the epoch of the Millstone grit ; and they were continued even after the Carboniferous, during the Permian. These submergences, although quietly carried forward, played havoc with the leaves, trunks, and stumps, floating them away for burial by the in-washed sediments. Some of the transported stumps may occasionally have had aboard large stones which they finally dropped, thus putting an occasional " bowlder " into the forming beds. The encroaching waters at times flowed with great force and plunging waves, as is shown not only by the formation of coarse gravel beds (now conglomerates), but also by the erosion of the rock deposits, and in some cases of the beds of vegetable debris. In Ver- milion County, 111., as observed by F. H. Bradley, a portion of the Upper Coal-measures, including shales, argillaceous limestones, and two coal-beds, were carried away to a depth of 60 feet ; and, in the depression thus made, a sandstone, which belongs at the top of the series, was laid down so as to fill and overlie it. Also, on the same authority, in Vermilion County, Ind. (adjoining the county just mentioned), the Millstone grit (here a pebbly sandstone), under the Coal-measures, is cut off short and followed horizon- tally by shale and limestone ; as if the grit stood as a bluff in the waters, in which the latter rocks were deposited. Other evidences of erosion have been, described from these states, and also from Ohio, Kentucky, and Missouri, The change of level over Iowa, Illinois, and Missouri, which permitted the Coal-measures to spread northward beyond the limits of the Chester lime- stone, the last of the Subcarboniferous beds, and even beyond the Kinder- hook beds, was of the same nature with the oscillations above referred to. No unconformity with the Subcarboniferous was produced except that of overlap. The little value, as regards time divisions in geological history, of unconformity by overlap or erosion is well illustrated by the facts here stated. The coal-beds are thin compared with the associated rocks. But the time of their accumulation, or the length of all the periods of verdure together, may have far exceeded the time occupied in the accumulation of sands and limestones. If there were but 100 feet of coal in all, it would correspond to more than 500 feet in depth of vegetable debris. The sands and clays which came in after each time of verdure put under heavy cover the thick bed of vegetable debris which had accumulated, and thus the decomposition of the plants and the change to coal took place, under the best of conditions for coal-making. In some regions the coal-plants may have been drifted to their places of deposit ; but this was not the usual way in North America. The great marsh from which proceeded the Pittsburg coal-bed of the Upper Productive Measures, according to J. J. Stevenson, was the "parent marsh " also of the coal-beds above it in the series, times of temporary burial being indicated by the intervening beds of shale and sandstone during the progress of a very slow and intermittent subsidence. A coal-bed itself bears evidence of alternations of condition in its own lamination, and even in the alternations in its shades of color. A layer one 710 HISTOBIGAL GEOLOGY. eighth of an inch thick corresponds to an inch, at least, of the accumulating vegetable remains ; and hence the regularity and delicacy of the structure are not surprising. Alternations are a consequence of (1) the periodicity in. the growth of plants and the shedding of leaves ; (2) the periodicity of the seasons, the alternations of the season of floods with the season of low waters or comparative dryness ; (3) the occurrence, at intervals of several years, of excessive floods. Floods may bring in more or less detritus, besides influencing the fall and distribution of the vegetation. There may have been great variations in the length of time before the peat-like vegetation after its formation was put under the pressure of beds of clay or sand; and the precise quality of the coal would be varied thereby, the decomposition of the vegetation depending on the amount of water, the composition of that water, and the length of time exposed. In some parts of the marshes there were pools or lakes where the vege- tation was long steeping and so becoming reduced to a pulp, to the oblitera- tion of all bedding; and in such places, according to Newberry, cannel coal was often formed ; for it usually constitutes locally the lower parts of a coal- bed, though sometimes making the whole thickness. And, as such ponds or lakes were likely to have their living species, so a bed of cannel coal often contains remains of fossil Fishes, Eurypterids, Crustaceans, and other species. The Eurypterus in its bed of Ferns figured on page 677 was obtained from a locality of cannel coal. In conclusion, the Coal period was a time of unceasing change, eras of verdure alternating with others of wide-spread waters, destructive of all the vegetation and of other terrestrial life except that which covered regions beyond the Coal-measure limits. Yet it was an era in which the changes went forward for the most part with such extreme slowness, and with such prevailing quiet, that, if man had been living then, he would not have sus- pected their progress. In Europe the conditions were similar, in the main, to those of America. The succession of Carboniferous rocks and coal in the British Isles exceeds much in thickness that in any part of Europe, very much as that of Nova Scotia exceeds that of Pennsylvania and the states west. The greater thick- ness of the formations (if not of the coal-beds), supposing the peat-making conditions to exist, has probably depended in each region on the extent of the slowly progressing subsidence or geosyncline. The longer continued and deeper subsidence in Nova Scotia favored greater thickness than in Pennsyl- vania; and the amount of subsidence in Pennsylvania determined greater thickness in that state than in Illinois. So it was also in the British Isles as compared with Europe. Far west of the Mississippi in North America the general submergence of the surface put a Carboniferous limestone over the region instead of profitable Coal-measures ; and far east in Europe, Russia has her barren coal-strata of vast extent, on both sides of the Urals. For the making of extensive Coal-measures a nice balancing of the land surface between submergences and emergences was a requisite. With a very PALEOZOIC TIME CARBONIC. 711 little too much emergence, even if only a few hundred feet, there would have been no marshes in North America ; for the land would have been drained. And with a little too much submergence, limestones or barren sediments of sand or gravel would have covered the region. North America was admirably arranged and poised for the grand result. South America probably lay a little too low, and vast plains, although situated just like those of North America, were left barren. Europe was not so well off as North America, because of the less extent of the level land surface, and the consequently less equable system of oscillations. Moreover, the lands of North America were on the wet border of the Atlantic, the western; and those of Europe, as at the present time, on the dry border, the two differ- ing now a fourth in amount of precipitation. METEOROLOGICAL CONDITIONS OF THE CARBONIC ERA. 1. Temperature of the air and waters. Using the facts from the rela- tions of existing plants to climate, that Perns and Lycopods thrive best in tropical and temperate latitudes, and Equiseta in temperate, it is inferred from the occurrence of coal-plants of each of these groups in all latitudes to the Arctic regions that the climate of the globe in the Carbonic era was no- where colder than the modern temperate zone, or below a mean temperature of 60 F. Similarly, the occurrence in Spitzbergen of Corals of the genera Lithostrotion, Cyathophyllum, and Syringopora, and of some species of Brach- iopods of twice the size they have in Europe, seems to show that the waters of the ocean were equally temperate throughout. As to excessive heat in the tropics, we have no evidence, since the common Carboniferous Brachiopods, Productus semireticulatus, P. longispinus, Athyris subtilita, and a Bellerophon near B. Urii are found in the Bolivian Andes. 2. Hygrometric conditions. With the atmosphere so genial and the ocean so warm, evaporation would have been excessive, rains abundant, and mists almost perpetual. Over the land on the favored side of the ocean, from the tropics to the higher temperate latitudes, atmospheric moisture would have reached its maximum. The great tropical Atlantic current a part of the world's machinery from the beginning of oceans and continents would have given moisture freely to the British Isles, more so than to Europe, and more to Spitzbergen than to Greenland and the western Arctic lands. More- over, Lycopods, Equiseta and most Ferns like shady as well as moist places. 3. Influence of the carbonic acid and moisture of the atmosphere. If the amount of carbonic acid used up in the making of Subcarboniferous and later limestones, and of coal and other carbonaceous products stored in the rocks of the Carbonic era, could be ascertained, the amount of carbonic acid abstracted from the atmosphere by the rock-making and coal-making of the era would be known. In view of the facts it is safe to say that the amount of carbonic acid in the atmosphere at the beginning of the era was at the least 3 in 1000 parts instead of 3 in 10,000, as it is now^ (See page 485.) 712 HISTORICAL GEOLOGY. The presence of this large percentage of carbonic acid and moisture would have given the atmosphere a correspondingly greater power of absorbing non-luminous heat, or that radiated by the warmed earth, and it therefore accounts for the uniformity in the earth's climate. With conditions in the climate and atmosphere so favorable, the plants would have been rapid in growth, in covering emerged lands with jungles and forests, and in supplying vegetable debris for the thickening peat-beds. Although the era was one of more clouds than sunshine, growth must have been, if possible, more exuberant than it is now in tropical America. The conditions were also favorable for decay. Old stumps of Lepidoden- drids and Sigillarids, poor in wood, decayed within as they stood in the swamps, while the debris of the growing vegetation, or, in some cases, the detritus borne by the waters, accumulated around them ; so that their hollow interiors received sands, or leaves, or bones, or became the haunts of reptiles, as was their chance. FORMATION OP COAL FROM THE BEDS OF VEGETABLE DEBRIS. The formation of coal out of the beds of vegetable debris probably only made a beginning while these beds lay as open beds of peat. The process is carried forward imperfectly in the modern peat-bed, and the best result is a poor coal, as it contains 25 per cent or more of oxygen. The deposits of clay or sand over the peat accumulations of the Carbonic era prevented the atmospheric oxygen from participating in the change, and to this is due the better product. The making of coal from wood has been explained on page 124, under Chemical Geology. The resulting mineral coal consists (1) chiefly of carbon; but (2) anthracite contains usually 2 to 5 per cent of oxygen and hydrogen, and the bituminous coals often 12 per cent in weight of oxygen and 4 to 6 of hydrogen; while brown coal, the bituminous coal of later formations (which ordinarily gives a brownish-black powder), contains 20 per cent or more of oxygen with 5 or 6 of hydrogen. Mineral coal, therefore, is not carbon, but a compound, or a mixture of two or more compounds, of carbon, hydrogen and oxygen, associated proba- bly with some free carbon in anthracite, and possibly in some or all bitumi- nous coal. In this view, coals are mainly oxidized hydrocarbons, or mixtures of them. They are feebly acted on by ether or benzine, if at all, and hence contain little or no mineral oil, or only a trace of any soluble hydrocarbon ; but, at a high temperature, hydrocarbons (compounds of hydrogen and car- bon) are given out, and often very abundantly, in the form of either mineral oil, tar, or gas. The process of the conversion of woody material into coal is briefly described on the page referred to. The vegetable material from which coal is made may be (a) woody fiber ; (6) cellular tissue ; (c) bark ; (d) spores of Lycopods (Lepidodendrids, etc.) ; (e) resins and associated substances. The following is the composition of (1) dried wood in the mass ; (2) cork (the PALEOZOIC TIME CARBONIC. 713 bark of Quercus suber) ; (3) the spores of Lycopods ; (4, 5, 6) the common kinds of mineral coal; and (7) peat or vegetable material, partly altered to the coal-like condition. I. Woody ingredients Carbon Hydrogen Oxygen Nitrogen 1. Wood 49-66 6-21 43-03 1-10 2. Cork 65-73 8-33 24-44 1-50 = 100 3. Lycopod spores 64-80 8-73 20-29 6-18 = 100 II. Coal products 4. Anthracite 95-0 2-5 2-5 5. Bituminous coal 81-2 5-5 12-5 0-8 6. Brown coal 68-7 5-5 25-0 0-8 7. Peat 59-5 5-5 33-0 2-0 The relations of these woody materials and coals are still better exhibited in the following table, giving the atomic proportions of the constituents, car- bon being made 100 ; the atomic equivalents of carbon, hydrogen, and oxygen being respectively 12, 1, 16. Carbon Hydrogen Oxygen 1. Wood '. 100 150 65 2. Cork 100 150 30 3. Lycopod spores 100 166 24 4. Anthracite 100 33 2 5. Bituminous coal 100 83 12 6. Brown coal 100 96 27 7. Peat : 100 112-5 40 There was little ordinary bark in the beds of vegetable debris, since the cortical part of Lycopods, Ferns, and Calamites is not of this nature ; although nearer coal in constitution than true wood, bark resists alteration longer, and is less easily converted into coal. The spores of Lycopods often retain their amber-yellow color in the coal, although undoubtedly changed in constitu- tion. Resins, which are still nearer coal in the amount of carbon, but hold less oxygen, are found mostly as resins in coal, especially when they are in lumps or grains, but of somewhat altered composition. It is probable that, in the making of bituminous coal, at least three fifths of the material of the wood were lost ; and in the making of anthracite, about three fourths. Besides this reduction to two fifths and one fourth by decomposition, there is a reduc- tion in bulk by compression ; which, if only to one half, would make the whole reduction of bulk to one fifth and one eighth. On this estimate, it would take five feet in depth of compact vegetable debris to make one foot of bituminous coal, and eight feet to make one of anthracite. For a bed of pure anthracite 30 feet thick (like that at Wilkesbarre), the bed of vegeta- tion should have been at least 240 feet thick. Anthracite coal is a result, according to most writers on the subject, of the action of heat on bituminous coal, under pressure, attending an upturn- ing of the rocks, the heat driving off nearly all volatile matters it could develop, and so leaving a coke (the anthracite) behind. Made in this way, 714 .(:: HISTORICAL GEOLOGY. the reduction, in the case of anthracite, would be to about one eighth, as above estimated. The average amount of ash in anthracite ought, conse- quently, to be nearly half greater than in bituminous coal. The production of the anthracite of eastern Pennsylvania was referred to the action of heat on ordinary bituminous coal first by H. D. Rogers, on the ground of the upturned and flexed condition of the rocks in that part of the state. The upturning fades out to the northwestward, and the Wilkes- barre anthracite region is on its outskirts. The heat produced in the rocks by the upturning need not, for the result, have been either great or much prolonged ; moreover, it would have spread laterally from the area of great- est disturbance, more or less far into the outskirts, as is well exemplified in various metamorphic regions. The following are other facts favoring this origin of the anthracite : (1) The coal of the upturned and more or less metamorphic Coal-measures of Rhode Island is the hardest of anthracite. (2) The coal of the Carboniferous Coal-measures of western Pennsylvania, and that of the states farther west, where the beds are nearly horizontal, is, throughout, bituminous coal and not anthracite. (3) Variations in the con- ditions of the coal-making areas over the globe have led to various kinds of coal without making anthracite. Brown coal, or that containing a large percentage of oxygen, is known to form where there is much access of air ; and cannel coal, a kind rich in oil-producing hydrocarbons, and little oxygen, under conditions of prolonged steeping beneath a deep covering of sediments ; for all the characters of the beds associated with cannel coal indicate, as Newberry held, the fact of such a steeping of the bed of vegetable debris. These are the extreme results, except that more remarkable extreme, the loss of all the oxygen through union with carbon, and thereby the making of hydrocarbon oil or gas as the substitute for coal. Anthracite is not known among the products so made, except in regions of upturned rocks, or in the vicinity of igneous rocks. Graphite, a grade beyond anthracite, is formed from the excessive heating of mineral coal, as is proved in the metamorphic coal regions of Rhode Island, Worcester, and elsewhere. GENERAL OBSERVATIONS ON THE PALEOZOIC ERAS. GROWTH OF THE AMERICAN CONTINENT. 1. Facts connected with Us growth. The facts which have been presented sustain the view that the American continent throughout Paleozoic time was gradually growing in its rock formations and dry land, and thereby extend- ing from the Archaean nucleus southeastward and southward, but not much in a southwestward direction. It is 'manifest, also, that after the Lower Silurian era had passed, the growth took place mainly through processes at work over the great Continental Interior, a vast American Mediterranean Sea, bounded on the north, northeast, and east, by Archaean confines. More- over, the eastern areas of progress in New England and beyond had like- PALEOZOIC TIME CAKBONIC. wise Archaean confines, even during Cambro-Silurian time, each having been an independent trough or basin. In the Acadian trough the subsidence carried down the bottom of the trough as deposition went forward, but not the Archaean ridges along the confines ; for if these Archaean ridges had sub- sided also, they should have jiad, at the beginning, the extremely improbable height of 30,000 or 40,000 feet. The Acadian and the Gaspe- Worcester troughs were sinking, and receiving, in some parts, if not generally, formation after formation, to the close of the Carboniferous period ; and the Connecticut- valley trough, to the middle or later part of the Devonian era ; and this was not the last, as will be shown, of the rock-making carried on in the Acadian and Connecticut-valley troughs. The western part of the Continental Sea had also its areas of subsidence and deposition. Only subsiding troughs received thick deposits for the various formations. 2. Diversities in kinds and in thickness of rocks. The vast Continental Interior, shut away from the more destructive forces of the ocean, afforded the most favorable conditions possible for the growth of aquatic life, and therefore for the making of limestones; and the life had no doubt the luxuriance prevailing in the existing coral reef seas of the tropics. What this degree of luxuriance is at the present time may be well learned from the admirable photographs of a volume by W. Saville Kent on The Great Barrier Reef of Australia. To see the reefs themselves is better ; but this not being readily attainable, the geological student, who would ap- preciate the profusion of life, and something of the beauty of Paleozoic reef- grounds, should see the photographs. The colors are absent, but there is everything else in the pictures. The species represented are modern Corals of various kinds and forms ; but it will be easy, afterward, to think of vast areas of Crinoids, ancient Corals, and other Paleozoic productions ; for the result is the same in kind, if shell-making Mollusks were the chief kind of life. He would learn also the pertinent fact that limestone-making is not necessarily, or ordinarily, deep-water work. The effects of the tidal and wind-made currents in forming fragmental accumulations within the Interior Sea, especially along its borders, have been variously illustrated in the preceding pages, with special reference to those of the northeast and east ; and there has been brought out to view, also, the contrast with those of the limestone formations over its interior. This contrast was augmented through each of the successive periods by the con- trast in the amount of subsidence in progress : over the Interior Sea, but little, the formations only 3000 to 6000 feet thick ; over the eastern portion, a great subsidence, 30,000 to 40,000 feet, because included within the area of the subsiding Appalachian trough. In the Continental Interior, the Paleozoic rocks are full two thirds limestones. The coal formation there has many limestone strata; the Subcarboniferous consists mostly of limestone; the Devonian and Upper Silurian strata are chiefly limestone ; the Lower Silurian, even through the Hudson period, mostly limestone; and the Cambrian chiefly limestone. The intercalations of strata of sandstone and shale indicate 716 HISTORICAL GEOLOGY. the varying locations and effects of the marine currents, owing to varying depths and changing outlines of the land. The rocks of the northern border of the Interior area include much less limestone than those of the more central portion. 3. Maximum thickness of the rocks in North America. The maximum thickness of the rocks of North America is not known. The methods of measurement of upturned rocks give so very doubtful results and lead generally to so large overstatements, that a trustworthy estimate cannot be made. It is, however, probable that the maximum thickness of the Cambrian is at least 20,000 feet, though only so where the rocks are mostly f ragmental ; of the Lower Silurian, 18,000 feet ; of the Upper Silurian, 7000 ; of the Devonian, 14,000 ; of the Carbonic, 16,000 ; making a total of 75,000 feet. The relative maximum thicknesses of the rocks have been used, first by S. Haughton, as a means of deducing the relative duration of geological eras and periods. There is great doubt over conclusions based on this criterion, because thickness is dependent so generally on a progressing subsidence no subsidence giving little thickness, however many the millions of years that may pass. But as it is the only available method, it is still used. Limestones increase with extreme slowness, five to ten feet of fragmental deposits accumulating in the time required for one foot of limestone. This general fact at least is plain, that Eopaleozoic time, or that of the Cambrian and Lower Silurian eras, was much longer than all the rest, for, as shown on pages 509, 520, it continued on after the first appearance of Fishes and In- sects, types that were formerly supposed to date from the Devonian. The ratio for the Eopaleozoic, Upper Silurian, Devonian, and Carbonic is perhaps 7:l:2:2or8:l:2:2. BIOLOGICAL CHANGES AND PROGRESS. To appreciate the general system of biological progress, it is necessary to have some knowledge of the general principles under which successions of forms and structures were produced. The following is a brief review of some of the principles. 1. From the simple, regular, or primitive in structure to the specialized. Some of the changes included, in cases generally of rising grade, are the fol- lowing: (1) From a structure in which there are two or more functions to an organ, to one in which each function has its special organ (an organ being any part of a structure that is more or less independent in action, as even a digit or a tooth). (2) From a structure in which the organ correspond- ing to a special function has several uses, to one in which special forms exist in the same structure for each kind of use. (3) From simpler forms of spe- cialization to more complex forms, better adapted to the required use. (4) From any specialized form to others adapted to newly acquired uses, with either accompanying rise or decline in general grade of structure. (5) From structures in which the head has large sense-organs and mouth- organs, to those having all the organs small, and the parts well compacted. PALEOZOIC TIME CAKBONIC. 717 (6) From large aquatic structures to smaller and more concentrated terres- trial structures. 2. Approximate parallelism, in many cases under any tribe, between the geological succession of structures and embryological succession in the develop- ment of living organisms. On this subject see the remarks on page 401. 3. Degeneration. (1) In cases where progress is upward, or where there is no manifest decline in grade: (a) Degeneration of an organ to a more primitive form ; (6) diminished size and often complete disappearance of an organ (either from disuse, or in consequence of accelerated enlargement in associated organs). (2) In cases of decline in grade: Degeneration widely in a structure through changes that have the reverse order of those enum- erated in the preceding paragraphs, leading often through youth-like to embryonic forms ; producing low-grade structures that are nearly normal in form and activity ; also lower down, variously defective structures, sluggish in movement; and at the extreme limit of degradation in Invertebrates, structures that are incapable of locomotion after leaving the young stage ; also, where an animal becomes aquatic among Vertebrates, producing struc- tures which retain activity, become urosthenic and multiplicate, and often have great length of body and large size. Degeneration has its limits. Degenerate Mammals are mammalian in their more fundamental characteristics. Degenerate Crustaceans are Crus- taceans still, as they show in their embryonic development. 4. From diffuse structures to concentrated. Since the brain or cephalic ganglion, besides being the source of physical energy, and the chief seat of sensorial energy, is the center of control of all the forces of the structures except the involuntary, concentration consists in a shortening of the radius of control, or the distance through which it has to act. Compare a Lobster with the highest of Crustaceans, a Crab ; or a Crab with its superior, an Ant. Some of the cases included are the following: (1) From a much elongate structure the elongation chiefly posterior to an abbreviated structure. (2) From a multiplicate structure, or one having an excessive or indefinite number of body segments, pairs of limbs, articulations of limbs, etc. a pre- vailing feature of Articulates of the early Paleozoic to one consisting of a normally limited number of such parts and usually also an arrangement of these parts in two or three groups. (3) From a structure having the pos- terior part of the body the chief locomotive organ to one having regular pairs of limbs as the organs of locomotion, and having these pairs of limbs situated anteriorly in the structure ; in which case the structure is styled podosthenic (from the Greek for foot and strong) . (4) From a structure in which the posterior pair of limbs in Vertebrates is the strongest, and which is there- fore merosthenic (so-named from the Greek for thigh and strong), to one in which the anterior feet are the strongest, a structure styled prosthenic. 7 18 HISTORICAL GEOLOGY. PLANTS. The line of succession for Paleozoic terrestrial plants has been made apparently clear by the observation that the Rhizocarps, the simple and small, mud-growing Acrogens, few in existing species, of which Salvinia and Mar- silea are two of the four modern genera, were the probable source of the spores that so greatly abound in Devonian shales (Dawson). Through the Protosalvinia, according to this author, the line leads up to the Equiseta, that is, to the Calamites and Annularice of the earliest terrestrial flora. Another simple type of Cryptogam, related to the former in fructification, that of Selaginella, which is represented now by only one single genus and thus shows that it is a type of the past now dwindled, is regarded as the probable source of the Lepidodendrids, and through them of the Sigillarids, or semi-exogenous Acrogens, and of the Yews and other true Gymnosperms. The special type among these simpler Cryptogams that was precursor to the Ferns has not been ascertained. Since circinate vernation characterizes both Cycads and Ferns, and since a genus of Cycads, Stangeria, now exists in which the foliage is Fern-like, it is probable that the line to the Ferns led beyond to the Cycads, the other grand division of the Gymnosperms, and, therefore, that the Gymnosperms had a double source. In the Lepidodendrids, Sigillarids, and related species, Cryptogams reached their culmination, or their greatest expansion in number of species, and their highest perfection in type of structure. The Lepidodendrids have no species in the Permian period, and the Sigillarids none after it. Further, the Equiseta passed, through the Calamodendra, their time of maximum devel- opment during the Carboniferous period. The genus Calamites had later species, but they were smaller, and the associated Equiseta were of the inferior modern type. The Cycads culminated in later time ; and the same is true also of the more typical Gymnosperms the Conifers. INVERTEBRATES. 1. Hydrozoans ; Actinozoans. The Graptolites, Cambrian in their beginning and Lower Silurian in culmination, disappear with the Lower Devonian. The Cyathophylloid Corals, or Tetracoralla, also dating from the Cambrian, increase in number of genera and species in the Silurian; with other Corals make coral reefs in the Upper Silurian ; are in much greater numbers, and of larger size, and make still more extensive reefs, but undergo little increase in genera, in the Lower Devonian; then in the Lower Car- boniferous they almost disappear. Three of the species observed pertain to the three older genera, Cyathophyllum, Zaphrentis, and Phillipsastrea,' and three are new genera, Lithostrotion, Cyathaxonia, and Lonsdalia. The recent discoveries of the "Challenger" Expedition report a living species of a Cyathophylloid Coral from the bottom of the ocean. PALEOZOIC TIME ^CARBONIC. 719 The Favosites ended in the Devonian, but related tabulate Corals still exist. 2. Echinoderms. Cystoids, one of the early Cambrian types, the simplest of the Crinoid tribe, embryo-like in their want of symmetry, are unknown after the Devonian. Crinoids, also Cambrian, multiply in genera and species through the Silurian and Devonian, appear under a marvelous diversity of forms in the Subcarboniferous period, and then rapidly decline, few appearing in the Permian, and none of the same paleozoic type in after time. The next period, or that commencing the Mesozoic, has more modern forms under the genus Encrinus, closely related to the living Pentacrinus. Starfishes commence in the Cambrian, and Echinoids, the higher Echino- derms, in the Silurian. The latter are abundant in the early Carboniferous era, but they do not lose in Paleozoic time their low-grade multiplicate characteristic ; that is, the excessive number of vertical series of plates in the shell. 3. Molluscoids. The Brachiopods, earliest Cambrian in origin, the most abundant of all Paleozoic animal life in species, and in individuals under species, had the larger part of the groups, to which they are referred, intro- duced in the Cambrian and Lower Silurian, but were most numerous in genera and species in the Upper Silurian and Devonian. And although of many species and few genera in the Carboniferous and Permian, the type appears to have lost, at the close of the Permian, all the genera then existing excepting four. These are: Lingula, Crania, Spirifer, and Wiynclionella ; all of these continue into the Mesozoic, showing remarkable adaptability to varying conditions. Further study may subdivide the genera ; but the general fact remains as regards the groups. The early Cambrian Orthis group continued through Paleozoic time, but appears to have ended at its close. 4. Mollusks. The tribe of Pteropods if the species, so referred, rightly belong here had predominance over other Mollusks in the Early and Middle Cambrian, the species being many and large. They were numerous also in the Lower Silurian ; but they diminish in numbers afterward. Conulariae of much more uncertain relations existed in the Upper Cambrian, but had their largest species in the Silurian, Devonian, and Carboniferous. They are rare fossils afterward ; the last known is from the Lias. Lamellibranchs and Gastropods, commencing in very small forms during the Early Cambrian, increased slowly in number of genera through the Paleozoic, without reaching a culminant condition in either of their higher divisions. The Cephalopods also culminate after Paleozoic time. One of the early genera, Orthoceras, had species of large size through the whole Paleozoic, and survived until the middle of the Mesozoic. 5. Limuloids. Limuloids of Eurypterid type commenced in the Lower Silurian, have species of great size in the Upper Silurian and Devonian, in which era they passed their culmination, and ended with small species in the Carboniferous era. The family of Limulids, a branch from the earlier 720 HISTORICAL GEOLOGY. Limuloids, appeared in the Silurian. They existed through the Carbon- iferous era, and under more compacted forms have been continued to the present time, four species now representing the genus Limulus, one North American, and three East Asiatic and East Indian. The Carboniferous genera Belinurus and Prestwichia represent, under an adult form, rather closely, the young of the modern Limulus ; and Cyclus Packard considers as representing a still younger embryonic stage of Limulus. 6. Crustaceans. It is stated on page 526, that Trilobites had their culmi- nation in number of genera, and in number, size, and grade of species, in the Lower Silurian. They continued, with few new genera, but under many new/ species, in the Upper Silurian, and appeared under some extravagant spiny forms during the Devonian ; but afterward, in the Carboniferous era, the species were few and simple, only a score being known. The number of new Carboniferous genera yet found is only two, and these are closely related to the Devonian Proetus. Here the type ends. No other subdivision of Crustaceans appears to have passed its culmina- tion in Paleozoic time excepting that of the Ostracoids, or the bivalved Crustaceans (page 525). The Cirriped or Barnacle tribe, a degenerate group, derived from some family of Ostracoids, as remarked on page 421, and one of the lowest stages of Crustacean life, appeared as early at least as the Lower Silurian. Other tribes of Crustaceans continue to expand. True Isopods make their appearance as early as the Devonian, and probably in the successional line of the Trilobites. The Decapods are represented by Macrurans (or Shrimps) in the Devonian, and by Brachyurans (Crabs) in the Carboniferous. Trilobites and many of the so-called Phyllopod Crustaceans are examples, as has already been stated, of multiplicate forms, or those having an excessive number of segments and members. The Early Cambrian Protocaris of Walcott (page 474) is a good example of a multiplicate, Apus-like Phyllo- pod, precursor of the true Decapod type. But normal numbers in segments exist in some of the " Phyllopods," even those of the Cambrian, the abdominal segments being reduced in number to six, the normal number in the Crusta- cean type, and in the same Phyllopods the thorax also has apparently its normal number of body segments ; in which case they are not multiplicate, unless in legs, and these are not in sight in the fossil specimens. With the appearance of Tetradecapods and Decapods in the Devonian, typical num- bers, as to body segments and limbs that is, for all parts of the structure have full expression; for the Isopods appear to be (in view of the researches of Walcott, Matthew and Beecher) essentially non-multiplicate Trilobites. 7. Derivation of Limuloids and Crustaceans. As has been suggested by Lankester (and is recognized on page 423), it is probable that all the Articu- lates are successional to the Rotifers. There is reason for believing, further, that the type of Annelids, that of Crustaceans, and probably that of Limuloids, had their independent Rotifer origin. PALEOZOIC TIME CARBONIC. 721 The Nauplius, or larval form, of a Crustacean shows, by its having but three pairs of limbs (two besides an antennary pair), that the type is not succession al to a many-jointed Annelid, but rather to some type of Rotifer. The Eurypterids, the early form of the Limuloids, are related to Crusta- ceans in the number of body segments, it being 19, as in the Tetradecapods ; and in the fact that 13 of these 19 segments pertain to the thorax and abdomen. But the wide distinction exists that the Eurypterids have no thoracic or abdominal limbs, and the only true feet which they have are also at base mouth organs ; that is, organs that pertain to the head. Moreover, as has been shown to be true in Lirnulus by Packard and others, they do not pass through the Nauplius stage in their development. These diversities and agreements appear to indicate a derivation for the Limuloids nearly like that of the Crustacean type, but probably not from Crustaceans. But since Limuloids cannot yet be proved to have existed before the Trenton period in the Lower Silurian, a derivation from some species related to the Ceratio- carids is possible. Since many of the Eurypterids were fresh-water or brackish-water species, the transfer to fresh water may have been an incident attending the diver- gence ; and also an explanation of their attaining so great dimensions, fresh waters having been their protection. The large Eurypterids, several feet in length, would have been helpless among Sharks and Ganoids. 8. Myriapods, Arachnids, Insects. Arachnids and Insects have their Upper Silurian species, but the first of Myriapods yet found are from the Lower Devonian. The remains of Insects in the Lower and Upper Silurian, together with those of the Devonian and Carboniferous, indicate, according to Scudder and Brongniart, that Hemipteroid, Neuropteroid, and Orthopteroid species, and more or less intermediate forms, were then the common kinds. Nothing about the earlier forms of Insects is known. The existence of six pairs of wings instead of four, that is, one for each segment of the thorax, may have been a primitive feature ; but this is not considered probable. The great size of some of the Devonian and Carboniferous species is a remarkable feature of the age. A spread of wing exceeding two feet is a size now existing only in large Bats and Birds. The Neuropteroids and Orthopteroids were the predominant types; and among them were intermediate species, as has been already illustrated. The latter type as regards the family of Cockroaches, as explained by Scudder, culminated before the close of the Paleozoic. Previous to its close, the wings of the two pairs in these species were alike in diaphaneity, very nearly alike in size, and hence equally efficient as flying organs. But in the following period (as illustrated by specimens from Colorado), the anterior pair begin to show some thickening and obscuration ; and in the present era nearly all the species have the anterior wings coriaceous, and fitted to serve, as in Beetles, almost solely or solely as wing covers. The posterior wings, on DANA'S MANUAL 46 722 HISTORICAL GEOLOGY. the contrary, have retained their transparency, neuration, and use. Scudder remarks, further, that a similar change took place after the Paleozoic, in the Orthopteroids generally, though to a less extreme degree ; and it appears therefore that the Carbonic era was the time of culmination not only for the Cockroach family, but for the tribe as a whole. The change was a loss of locomotive function by the anterior pair of wings, and an example therefore of degeneration ; and it was attended, as Scudder states, by a great loss in the size of the species, and especially of the wings ; the mean length of the anterior wings in the Paleozoic species of Cockroaches being a little over an inch (26 mm.), and 40 per cent less in later kinds. Among Hemipteroid species, the Permian Eugereon Bockingi, of Germany, had the wings of both pairs similarly diaphanous, while in the Plithanocoris of the Permian of Missouri, described by Scudder, the anterior pair were much thickened; the result, probably, as in the Orthopteroids, of degeneration. It is probable that Carboniferous Beetles had a like method of origin from Insects having four diaphanous wings ; but the line of descent remains unknown. The Scorpions of the Upper Silurian are much like those of modern time. The type is the lowest among the tribes of Arachnids, notwithstanding their size. As in a Crustacean or Eurypterus, the body (Fig. 799) obviously consists of a cephalothorax and a long abdomen. True Spiders have not yet been found in rocks earlier than the Carbon- iferous ; and this is probably because Spiders are so little likely to be fossil- ized ; for they are not only smaller animals than the Scorpion, but also they are unlike them in not having a durable exterior. 9. Derivation of Arachnids. The line to the lower and earlier Arachnids that is, to the Scorpions leads up, according to Van Beneden, Packard, and others, from the early Pterygotus-like Limuloids. The early Scorpions, as well as the modern kinds, have the same number of body segments as a Eurypterus or Pterygotus : namely, seven thoracic and six abdominal (pre- cisely the normal number in Crustaceans) ; the same cephalic relations of the legs ; the same absence of abdominal appendages ; a like absence of thoracic appendages from all the segments excepting the first two ; and similar func- tions in the members pertaining to these two segments. Further, accord- ing to B. Peach, these early Limuloids sometimes have, like the Scorpions, pairs of "combs" or pectinated organs on the underside of some of the thoracic segments. But in this change from an aquatic to a terrestrial species the upward progress in structure was great. The four posterior pairs of feet in the terrestrial Scorpion have no longer the low-grade feature of serving for jaws as well as feet, but are simply feet ; they are the chief organs of locomotion, and only those of the anterior pair are appendages to the mouth. The antennae are shortened to pincers (falces) that also serve the mouth. The four pairs of feet are thus cephalic organs, if comparison be made with the Limuloids and Crustaceans ; though in Arachnology, they are called PALEOZOIC TIME CARBONIC. 723 thoracic. Air-breathing was another new feature ; and for this purpose parts of the body had air-vessels or tracheae which opened by breathing holes, or spiracles, on the under side of four of these " thoracic " segments. In the later true Spiders the body "had lost its Eurypteroid abdomen, but had still, in Paleozoic species, its distinctly segmented thorax ; and this thorax is the abdomen of Arachnology. (It is segmented in some modern species, while in others the subdivisions have become obsolete or are but faintly indicated.) The abdomen of the Eurypterid, however, exists as a slender jointed thread in Geralinura of Scudder, of the Carboniferous, which has its Illinois and also Bohemian species, and has survived till now in the modern Thetyphonus. 10. Derivation of Myriapods and Insects. Myriapods, although inferior to Insects, are as yet known only from the early Devonian. The Devonian species, and also those of the Carboniferous, are of the Milleped, or lower, doubly-multiplicate section of Myriapods, with one exception, that of the remarkable few-jointed, caterpillar-like Palceocampa of Meek and Worthen. The fact of a line of succession from Worms to Myriapods and from Myriapods to Insects has not been proved by geological discovery. The derivation of Myriapods from some type of Annelids is zoologically suggested, as long since recognized, by the apparently transitional form of Peripatus, a low-grade Myriapod resembling much the larve of some Insects, and by the like multiplicate structure of Annelids and Myriapods. It might be inferred also from the resemblance of the Palseocampa of the Illinois Carboniferous to the caterpillar of an Insect of the genus Arctia, as remarked by Scudder. Myriapods are regarded as the precursors of Insects, on account of their approximate resemblance to the latter in antennae and the appendages of the mouth, and because also of the worm-like form of most Insect larves, these larves appearing to be survivals of the Myriapod stage. In the change from an Annelid and Myriapod to an Insect, the multiplicate feature disappeared, and the number of parts became essentially the fixed normal number of the type, both as regards the body segments and their jointed appendages. The rise of grade from the Myriapod to the Insect involved the appropria- tion of the three body segments of the Myriapod bearing the three anterior pairs of feet (which correspond normally to half the body segments of the head of an Isopod Crustacean) for forming the isolated middle section of the body called the thorax, and the suppression of all the other pairs of feet. In both Spiders and Insects, the change involved also a general concentra- tion of the structure toward the cephalic nervous center; that is, a shortening of the range of cephalic control, and especially the distance to the posterior limits of locomotive action. While in the Cockroach, and related low-grade species, there is no proper metamorphosis, in higher Insects, as they rise in grade, the larval stage is lower and lower in embryonic level, becoming, in the highest, destitute of locomotive organs ; and this fact suggests that the larval stage results from an attendant retrograde embryonic change toward, and to, a line parallel with 724 HISTORICAL GEOLOGY. the Myriapod type, and beyond this, to the memberless condition of the Worm. This accords with a common fact that the higher the species, the longer the stage of youth. The relations in body segments and limbs between the classes of Crusta- ceans, Limuloids, Arachnids, Myriapods, and Insects, are shown in the following table. The segments of the parts of the body are numbered along the left margin ; the zero opposite signifies that the segment, though present, has no appendage. CRUSTA- CEANS LIMULOIDS ARACHNIDS MTRIA- PODS TKTQPPTS Tetradecapods Eurypterus Pterygotus Limulus Scorpion Phrynus Lithobins 1. 1st Ant. 1 ] Ant. Ant. Falces j Falces 1 Ant. TS Ant. 2. 2dAnt. M-P. M-P. M-P. M. J M M. j h M. oS M. 1 3. M. | M-P. 1 M-P. "i M-P. rt P. P. M MX. KM Mx.&L. w 4. MX. W M-P. ffi M-P. w M-P. ffi P. P. 1 p i P } H 5. MX. M-P. M-P. M-P. P. P. i) S 6. MX. M-P. M-P. M-P. P. P. H P. P. 1: li 1. P. ] Fol. P. ] Fol. P. 1 Fol. P. 1 ' J5 ] P. 2. P. Fol. P. Fol. P. Fol. P. Comb P. 3. P. 4. P. o 1 1 o Fol. P. Fol. P. X P. p S3 09 o s 5. P. & H Fol. P. J H 1 P. | 6. P. Fol. P. s P. S 2 7. P. J J J - P. * 1. App. ] o 1 ] o ] ' o J P. 2. App. s s c c a 3. App. Fi a s 5 a 4. App. c ,2 -s i ^j P. 5. App. <- ^SS-3 .l 2 -g tltf In this table, the following abbreviations are used: Ant., antenna; App., pairs of jointed appendages, either pediform or branchial ; M., mandible ; MX., maxilla ; P., feet ; M-P., feet that serve also as jaws ; MX. & L. (under Insects), maxillae and labium ; Fol. P., foliaceous or lamellar feet or appendages. Under the Limuloids, the genus Eurypterus fails of antennae ; but they are present in Pterygotus, and are chelate ; and this chelate (or thumb-and- finger) form characterizes also the modern Limulus, the Scorpions, and the common Spiders. In the table, the two pairs of maxillae of Insects are assumed to belong to a single body segment, as held by many zoologists, including (as he himself informs the author) S. I. Smith; the table shows PALEOZOIC TIME CARBONIC. 725 that, with this admission, the thorax and head of an Insect are essentially homologous with the head of a Tetradecapod Crustacean. VERTEBRATES. 1. Fishes. The Pteraspid section of the Placoderms, having long verte- brated tails fitting them to be fleet scullers, commenced (according to the present state of the facts) in the Lower Silurian (page 509). Cotempo- raneously (the same locality attesting) there were normal Ganoids, the Crossopterygian, which till recently were supposed to have made their first appearance in the Devonian. Along with these there probably existed also the Chimseroids, precursors of the Selachians, a type of primitive features now almost extinct. The Devonian adds to these paleozoic tribes the Brachiate Placoderms, admirably armor-clad fishes. But they were short in body, and hence poor at sculling, but were furnished with pectoral limbs in the shape of arms that were seemingly fitted for crawling and grubbing over muddy or sandy bottoms rather than for swimming. Although the appendages are called "arms," and the Fishes were in appearance "brachiate" (Fig. 982, page 624), the pectoral fins (to which they correspond) are homologous with the hands in Vertebrates and not with the arms. They were a poor equip- ment for either aquatic or terrestrial service, and the species end with the Devonian. At the same time the Devonian waters were full, as has been shown, of Selachians, Dipnoans, and typical Ganoids, of great diversity in characters, and many of them unsurpassed at any later time in magnitude. Fishes appear to have reached their highest grade of vertebrate structure, and thus to have culminated in the Dipnoans, species that have not only lungs for breathing, as well as gills, but also, in the Ceratodus, a genus dating from the Carboniferous, a finger-like jointed midrib to the pectoral fin (Archypterygian), with jointed branches diverging from either side of it. No records of the precursors of Placoderms, Ganoids and Sharks have yet been found in the rocks. The little Amphioxus, of existing seas (page 418), is supposed to represent one of the early forms, because, while having the general characteristics of the class, it is strikingly like an Invertebrate in part of its embryological development. The Ascidians are probably degen- erate forms, as held by Lankester, derived from some species of still lower grade. All Fishes are in several ways eminently multiplicate species. This is seen in the number of vertebrae ; of articulations in the limbs when articula- tions exist; of teeth, and of tooth-bearing parts in the mouth. 2. Amphibians and Reptiles. The line from the Fishes to the Amphibians is supposed to have been from the Dipnoan section. The resemblance in Amphibians to the Ganoids generally is in many respects close, it extending even to the form and structure of their labyrinthine teeth ; and the Dipnoans 726 HISTORICAL GEOLOGY. already had the lung for respiration, which is the characteristic feature of all terrestrial Vertebrates. In rising from the multiplicate structure of the Fish to the grade of Amphibian, the Vertebrate type reached a fixed or normal limit in the number of limbs, in the number of the bones of the fore and hind limbs, including even the number of digits, but not in the number of articulations of the digits. In the typical species of the old Carboniferous Amphibians the fore limbs have the scapula, humerus, radius and ulna, wrist bones, and the five fingers characteristic of the higher Vertebrates. Further, in rising to Amphibians, the method of progression, which is urosthenic in Fishes, became podosthenic in the adult Amphibian. The young Amphibian, or Tadpole, retains the urosthenic feature and the gills of the Fish ; but in passing to the adult stage, when feet are developed, the higher Amphibians lose both the tail and gills and have only feet for locomotion. The tailed Amphibians are intermediate forms representing the stages of progress. The absence of limbs in the Amphibian Snakes of the Carbon- iferous is probably a case of degeneration. True Reptiles occur in the Permian. In this higher grade of Vertebrates the fish-like features of gills, and of tails for locomotion, are absent in the young state, and feet are throughout the locomotive organs. Besides, the number of joints in the digits of the fore and hind feet of these terrestrial Vertebrates has essentially the normal limit. But the teeth in the earlier species are still multiplicate in number and in series. One prominent difference between the Keptilian and Amphibian skeletons is the existence in Amphibians of two occipital condyles for the articulation of the skull with the first cervical vertebra, while in Reptiles there is but one. In this feature Mammals, as early stated by Huxley, are more nearly related to Amphibians than to Reptiles or Birds. REALITY OF THE PALEOZOIC WORLD. The term Paleozoic is not simply a name for a division of geological time. It expresses a profound historical truth. It signifies the reality of a Paleo- zoic character in the world's early life which was exhibited not only in the very earliest of plants and animals, but also throughout the succession of species, and so decidedly that the Paleozoic world stands out in bold contrast with the Mesozoic. This truth has the greater importance inasmuch as Paleozoic species were the earth's population for more than half of all post- Archaean time. The truth of this statement is obvious after the review of Paleozoic life on the preceding pages. Corals, Crinoids, Trilobites, Brachiopods and Mol- lusks, even of their highest group, that of Cephalopods, commence in the Cambrian and are prominent through the Paleozoic. Trilobites end near the close of Paleozoic time. The prolific Brachiopods at its close lose nearly all their Paleozoic genera; Crinoids drop their Paleozoic characteristics, and PALEOZOIC TIME CARBONIC. 727 Corals also with few exceptions ; Nautiloids lose nearly all their Orthoceras- like forms ; while the coiled Nautilus-like species culminate in the Carbonif- erous, and have few species and genera afterward. So the Insects had Paleozoic features which were dropped at the same time, and one division passed its time of culmination. The Placoderm, Dipnoan, and Ganoid Fishes, which were eminently Paleozoic types, culminated in the Devonian and Car- bonic eras, and only inferior Dipnoans and Ganoids existed later. Cryptog- amous Plants culminated in the Carboniferous era, and only the Calamites and some related genera, and a few genera of Ferns survived into the Mesozoic. Should discovery open to view earlier species than those now known in the Cambrian, they would be only earlier representatives of Paleozoic types, or their precursor embryonic kinds. And if some of these latter existed in preceding Archaean time, this fact would be parallel with the appearance of many Mesozoic types in the course of Paleozoic time. The disappearance of species at the close of Paleozoic time was not due chiefly to physical catastrophe, for the Trilobites had dwindled greatly by the close of the Devonian ; and similar expansions to culmination in many other tribes, with subsequently a commencing decline, have been mentioned in the preceding pages, both among plants and animals. How far such culminations were a consequence primarily of laws of growth it is not possible to say. There is no doubt as to their connection with physical changes in progress. One of these physical changes was the slow removal of carbonic acid from the atmosphere. The making of shells, corals, and Crinoid skeletons, and thereby the making of limestones, was, through Paleozoic time, dependent mainly on carbon abstracted from the carbonic acid of the air and waters ; and vegetation, so far as its products became stored in the rocks, in the form of coal, oil, gas, and other carbo- naceous products, involved a further abstraction, as explained on page 485. The purification of the air which was thus carried on was the means of fitting it for Spiders, Insects, and other terrestrial life, and afterwards for Am- phibians, and finally for Reptiles. Change in animal as well as vegetable types must have been involved in this using up of the deleterious carbonic acid. But the extent of its influence can only be conjectured. An examina- tion into the amount of carbonic acid which air can contain without being injurious to different kinds of Insects, and to Amphibians, Reptiles, and other species, would have much geological interest. Decline in the tempera- ture of the sea and air through Paleozoic time also had its influence. But it is not safe at present to attribute special facts to this cause. SECTION OP THE PALEOZOIC ROCKS OF PENNSYLVANIA. The following section of the Paleozoic rocks of Pennsylvania, published by H. D. Rogers, after the first survey of the state, is here added because of its geological and historical value. 728 HISTORICAL GEOLOGY. Lower Silurian. I. Potsdam. "Primal Series" of Rogers: sandstones and slates, 3000'-4000'. II. Calciferous. " Auroral " calcareous sandstone, 250'. Chazy. " Auroral " magnesian limestone, with some cherty beds, 5400'. Trenton. " Matinal " limestone, with blue shale, 550'. III. Utica. " Matinal " bituminous shale, 400'. Hudson. "Matinal" blue shale and slate, with some thin gray calcareous sand- stones, 1200'. Upper Silurian. IV. Oneida. " Levant Gray " sandstone and conglomerate, 700'. Medina. "Levant Red" sandstone and shale, 1050'; and "Levant White" sandstone, with olive and green shales, 760' : total, 1810'. V. Clinton. " S urgent Series," shales of various colors, both argillaceous and cal- careous, with some limestones, ferruginous sandstones, and iron-ore beds, 2600'. Niagara. Not well denned ; possibly corresponds with part of the " Surgent Series." Salina. "Scalent" variegated marls and shales, some layers of argillaceous limestone, 1650'. VI. Lower Helderberg. "Scalent" limestone, thin-bedded, with much chert, 350'; " Pre-meridian " encrinal and coralline limestone, 250' : total, 600'. VII. Oriskany. " Meridian" calcareous shales, and calcareous and argillaceous sand- stone, 520'. Devonian. VIII. Upper Helderberg, Cauda-galli. "Post-meridian" silico-calcareous shales, 200' to 300'. Corniferous. " Post- meridian " massive blue limestone, 80'. Marcellus. " Cadent " Lower black and ash-colored slate, with some argilla- ceous limestone, 800'. Hamilton. " Cadent" argillaceous and calcareous shales and sandstone, 1100'. Genesee. " Cadent " Upper black calcareous slate, 700'. Portage. " Vergent" dark-gray, flaggy sandstones, with some blue shale, 1700'. Chemung. "Vergent" gray, red, and olive shales, with gray and red sand- stones, 3200'. IX. Catskill. " Ponent " red sandstone and shale, with some conglomerate, 6000'. Carboniferous. X. Pocono. "Vespertine" coarse, gray sandstones and siliceous conglomerate at the eastward, becoming fine sandstones and shales at the westward, 2660'. XI. Mauch Chunk. "Umbral" fine red sandstones and shales, with some limestone, 3000'. XII. Millstone- grit, or Pottsville conglomerate. ' ' Serai " siliceous conglomerate, coarse sandstone and shale, including coal-beds, 1100'. Coal-measures. 2000'-3000'. POST-PALEOZOIC OR APPALACHIAN REVOLUTION. Paleozoic time closed with the making of one of the great mountain systems of North America the Appalachian, besides ranges in other lands, and in producing one of the most universal and abrupt disappearances of life in geological history. So great an event is properly styled a revolution. PALEOZOIC TIME CARBONIC. 729 MOUNTAIN-MAKING IN NORTH AMERICA. The various steps in the making of the Appalachian Mountain Kange, or Synclinorium, and the events of the prolonged catastrophe, have been reviewed at length on pages 353-357. It is there stated that general quiet prevailed over the continent throughout the Paleozoic eras, with the exception of the interval of Taconic upturning, and those gentle oscillations of level in the earth's crust that seem to have been always in progress. The extent and steps of progress in the geanticline of deposition, which began in the early Cambrian, has also been explained, and particulars mentioned as to its variations in eastern and western limits, as shown by the limits of the several formations ; and its inequalities in rate of subsidence over its different parts and in successive periods, as indicated (1) by the varying thickness of the formations from nothing to thousands of feet, and also (2) in the varying kinds of rocks from shales to conglomerates and limestones. The review of the facts relating to the history of the successive formations from the Cambrian onward has given greater definiteness and reality to the events. Moreover, it has derived new illustrations of the changes from the remains which the rocks contain of the life of the world. The varying con- ditions of the preparatory geosyncline during its progress have thus become strongly apparent ; and they will be much more so when the limits of the successive formations, now so well understood over New York, shall have been as thoroughly investigated by the paleontologist and geologist over Pennsylvania, the Virginias, and beyond. The general facts connected with the upturning of strata, 30,000 to 40,000 feet thick, which the geosyncline at the end contained, have also been reviewed ; and an account given of the flexures of the beds in many long lines, and the general parallelism of the flexures, but with interruptions and over- lappings, and of upthrust faults of 10,000 feet and more. Mention has also been made of curves in the course of the finished mountain range ; one bending from north-by-east in the northern or Catskill portion to east-northeast in Pennsylvania, the whole nearly parallel with the eastern and southern outline of the nucleal Archaean mass ; the other, from Pennsylvania to Alabama and Mississippi, and becoming at the south nearly parallel with the Mexican Gulf. The courses and character of the flexures in the nearly east-and-west portion of the range in Pennsylvania are well shown on Lesley's topographic map of the state, although greatly disguised in consequence of the denudation that has taken place since the time of mountain-making. A copy of the map (Fig. 1153) is here introduced, exhibiting the courses of the multitudes of ridges, and their bends and terminations either side of the channel of the Susquehanna River. The map is here reduced to too small a scale to show all the minor flexures, and a diagram is added (Fig. 1154) giving in simple lines the courses, positions, and bends of the various ridges over the center of the state. 730 HISTORICAL GEOLOGY. 1153. PALEOZOIC TIME CARBONIC. 731 On the map on page 730 the lines TS, 1C are the outline of the Triassic area of Pennsylvania. The transversely lined areas on its western part are the oil-producing and gas-producing areas of the state ; the former light-lined, the latter dark-lined. The character of the ridges in this east-northeast portion of the ranges, as they approach the Susquehanna on either side, their many small zigzag flexures (well exhibited in the diagram), and at the same time the wider spacing of the ridges there than to the westward, where the Appalachian Range takes its more normal northeasterly course, are points to be noted. These differences appear to have resulted in some way from the inequality of the action of the orogenic lateral pressure in the two directions ; that is, at right angles to the normal northwesterly course, and to the less normal north- northwesterly. The course of the Susquehanna River appears to have been determined by the warpings then occasioned. 1154. -WTc Diagram, showing the courses and flexures of the ridges in central Pennsylvania. From map by Lesley. Abbreviations: C, Chambersburg ; Ce, Carlisle; D, Danville; G, Gettysburg; H, Harrisburg ; Hn, Huntington ; L, Lewisburg ; NB, New Bloomfield ; P, Pottsville ; K, Eeading ; W, Williamsport ; Wk, Wilkesbarre ; Y, York. The map also shows the parallelism between the positions of the oil-well and gas-well areas in western Pennsylvania and the trend of the mountains, and indicates a relation in their positions to the mountain structure, as already pointed out. The region of the anthracite is to the eastward, as will be seen on comparison with the map on page 730 ; while to the west and south- west there are the great areas of bituminous coal. The Appalachian Range is a single mountain individual, or synclinorium, nearly 1000 miles long. But it is only one of the ranges made at this time 732 HISTORICAL GEOLOGY. in eastern North America. There was another to the eastward, the Aca- dian Range, extending from Newfoundland probably to Narraganset Bay in Rhode Island, a distance exceeding 800 miles, and still another, that of the Ouachita Range in Arkansas (pages 380, 389). In the Acadian trough the beds of Cape Breton and Nova Scotia are variously flexed, and at the southern end of the trough, in Rhode Island and part of Massachusetts adjoining, there are like evidences/of disturbance ; and, moreover, the coal is changed to anthracite, and in some places to graphite. Since the close of the Lower Silurian was an epoch of upturning for the beds then in the northern part of the Acadian trough, it is probable that it was so for the whole trough, including the coast of Maine and the Cambrian beds of the Boston basin. But there is no direct evidence as to this or to later times of disturbance along the belt except in the Nova Scotia, New Brunswick, and Maine regions. Slates, grits, conglomerates, and eruptive rocks occur in the Boston basin above the Cambrian, without fossils or any other evidence of age ; and, as described by Crosby and Bouv6, they may be of any period from Cambrian to Carboniferous. The three ranges, the Appalachian, Acadian, and Ouachita, constitute together the Appalachian Mountain System. The length of the whole region of orogenic disturbance is over 2000 miles. The Gaspe- Worcester trough, which contains some carbonaceous beds, with graphite, at Worcester, underwent post-Carboniferous upturnings. But details are wanting. It is probable that various dislocations and anticlines over the states north along the Mississippi valley date from this epoch ; and in Illinois, several lines of dislocation, between 'northwest and west-northwest in trend, have been described by Worthen (G-eol. Rep., i., 1866). (1) One crosses the Mississippi in Alexander County at the " Grand Chain," where the Trenton forms a ledge across the river ; (2) another at Salt Creek Point in Monroe County ; (3) another below St. Louis, near the south line of St. Clair County ; (4) another at " Cap au Gres," in Calhoun County, " where there is a downthrow of the beds on the south side of at least a thousand feet," and the St. Peters sandstone constitutes the "Cap au Gres " ; (5) another, north-northwest in trend, farther north, intersecting Rock River, Grand Detour, and the Illinois River in La Salle County, between La Salle and Utica, bringing the Lower Magnesian limestone to the surface ; (6) another, traceable from Bailey's Landing on the west side of the Mississippi to Shawneetown on the Ohio. Of the fifth, he states that " it elevates the Coal-measures 300' to 400', showing that the disturb- ance took place at a period subsequent to the deposition of the Coal formation" ; and afterward adds, with reference to the whole series of upturnings, " It is impossible, with the evidence before us at this time, to fix with certainty the relative dates of these dis- turbances ; but it seems quite probable that none of them date back to a period anterior to the Carboniferous epoch ; for we find, in general, no want of conformity between the uplifted strata and any of the superincumbent Paleozoic beds." There are other lines of uplift or undulations farther north across Iowa, as described by McGee (llth U. S. Geol Surv., Annual Beport, 338, 1891), which have a trend of N. 30-40 W. The time of origin is stated to be doubtful, except for one anticline, that of the Cedar Valley, near Davenport, Iowa, which ' ' does not appear to affect the Coal- measures at Davenport and Rock Island." So far as yet ascertained no great mountain-making events occurred at this time over the Summit Region of the Rocky Mountains. The Carbonif- PALEOZOIC TIME CARBONIC. 733 erous rocks appear to have been followed by the Mesozoic without extensive intervening upturnings in the region of the Wasatch and through the whole length of the mountains, from western Texas and Mexico to the Arctic Seas. But west of the Wasatch belt, in the mountain ridges of the Great Basin to the meridian of 117^ W., according to King, Carboniferous limestone is to a considerable extent the surface rock, there being no overlying Mesozoic strata ; and this limestone and the older Paleozoic formations are flexed and faulted in mountain-making style. The time of the upturning is uncertain because of the absence of later beds except over the region beyond the meridian of 117^. But, as King implies, it took place probably at the close of the Paleozoic. The Eureka Mountains in the Great Basin (near 116 W. and 39 N.), described by Arnold Hague (Geol. of the Eureka District, U. S. G. S. Memoirs, 4to, vol. xx., 1892), are one of the mountain groups of eastern Nevada, which probably was upturned at this time. The prominent ridges, which were produced largely by faults and uplifts (their maximum displacement 13,000') , are : the Prospect Ridges, consisting of Cambrian and Silurian rocks ; the Fish Creek Mountains, Silurian ; the Silverado and Country Peak, Silu- rian and Devonian ; Diamond Mountain, Devonian and Carboniferous ; Carbon Ridge and Spring Hill, Carboniferous. The thickness of the formations, as deduced from several sec- tions, according to Hague and Walcott, is as follows : Cambrian, 7700' ; Silurian, 5000' ; Devonian, 8000'; Carboniferous, 9300', in all 30,000'. This great thickness indicates, as .Hague suggests, that a profound geosyncline north and south in trend was here made. The Eureka, Carboniferous, Devonian, and Silurian beds have been traced from the Eureka district westward to that of the Pifion Range, which is an indication that the latter range participated in the geosyncline. How far north the belt extends remains to be ascertained. The Archaean ridge of the East Humboldt Mountains stands to the east and north of the Eureka Range. The Eureka geosyncline was wholly independent of that of the Wasatch, as shown by the thicknesses of the several Paleozoic formations occurring in the two ; for the thick- ness of the Silurian of the Wasatch is only 1000', of the Devonian, 2400', while that of the Carboniferous is 14,000'. Whether the Silurian unconformability in the Eureka region between the Lone Mountain limestone and the underlying quartzyte is a result of an upturning at the close of the Lower Silurian, or of later faulting, does not appear to be determined by the observed facts. UPTURNINGS IN FOREIGN COUNTRIES. Regions of upturned rocks are the only kind in which there is good reason to look for unconformabilities. Through the course of Paleozoic time in Europe, disturbances appear to have been more frequent than in America. But they were inferior in extent to those at its close. Murchison remarks that the close of the Carboniferous period was specially marked by disturb- ances and upliftings. He states that it was then " that the coal strata and their antecedent formations were very generally broken up, and thrown, by grand upheavals, into separate basins, which were fractured by number- less powerful dislocations." In the north of England, as first shown by Sedgwick, and also near Bristol, and in the southeastern part of the Coal- measures of South Wales, there is distinct unconformability between the 734 HISTORICAL GEOLOGY. Carboniferous and lowest Permian, and this is true also in Lancashire and Yorkshire. The "Hercynian system" of Bertrand includes a long range of dislocated Devonian and Carboniferous rocks extending from Brittany to the Vosges and Ardennes, and beyond along the Black Forest, the Harz to Bohemia. The line corresponds nearly with the " System of the Rhine" of de Beaumont, which was upturned, as he showed, before the Triassic period. The " great fault " in the Alps raising the crystalline schists in the zone of Mont Blanc, between the Bernese Alps on the east and the maritime Alps on the southwest, was made between the Carboniferous and Triassic (or the Lias, where the Trias is absent). The coal-formation, which is extensively distributed in the Swiss Alps, is in part semi-crystalline. In Russia, strata are generally horizontal or nearly so, and lie above the Carboniferous without unconformability. In the closing part of Paleozoic time, either after the Carboniferous or after the Permian, a belt of rocks along the Urals was folded and crystallized ; for Carboniferous rocks are flexed and altered in the same manner as in the Alleghany region. But the backbone of the Urals is Archaean. NORTH AMERICAN GEOGRAPHY AFTER THE REVOLUTION. The various movements over North America closing Paleozoic time ended, as announced on page 714, in making dry land of the eastern half of the continent. The western coast within the United States extended along a north-and-south line near the meridian of 95 W.. and farther north trended northwestward through British America, as delineated on the accompanying map (Fig. 1155). The dry land had its Appalachian Mountain chain, and was for the most part finished in its rock foundation, its mountains, and its store of coal-beds. The positions of the rivers and lakes are doubtful. There were, beyond ques- tion, a St. Lawrence River and other streams flowing off from Archaean lands. The Hudson River had been a small stream from the Adirondack s, merely the head of the present Hudson River, emptying into the waters of the eastern Continental Interior below Albany. But what course it took after the mak- ing of the Appalachians, remains to be learned from later records. The east- ern coast-line of the continent, south of New York, which was still outside of the existing position of the sea border, is placed on the map near that of the 100-fathom line the true margin of the Atlantic basin. For not only are all Paleozoic formations later than the Lower Silurian unknown on this part of the border, but also all marine formations of the Early and Middle Mesozoic. This was probably true, likewise, of the Gulf border. Whatever marine beds were formed are now deeply submerged. The burial of the shore region by Cretaceous and Tertiary strata prevents direct observation except through borings, and these have not yet been carried to a sufficient depth to decide the question. PALEOZOIC TIME CARBONIC. 735 Nearly all the western half of the continent was still a sea of varying depth, with perhaps its widespread sand flats. Only one large dry-land addi- tion to the western part of the continental area is known to have taken place ; it occupied, as shown by King, a portion of the Great Basin, over what is now eastern and central Nevada, having the meridian of 117| W. near its western limit. The western semi-continent was yet to be supplied with thick rock-formations and with its grander mountains ; and veins of gold, silver, and other metals were to be formed, and coal-beds to be accumulated, before finally the emergence of "the Great West" from the waters was completed. 1155. Map of North America after the Appalachian Revolution. Disappearance of life. The disappearance of life at the close of Pale- ozoic time was so general and extensive that no Carboniferous species is known to occur among the fossils of succeeding beds, not only in America and Europe, but also over the rest of the world. The fact is learned better from Europe than from America; for in Europe remains of marine life occur in beds representing the early part of the following period, while in America, the first marine fossil known from the Atlantic border is of the Cretaceous period. A large part of the old tribes of the sea and land continues on, spe- cies having survived through the time of catastrophe ; and yet their species did not find burial among later fossils. Many underwent modifications and appear later under new forms, and thereby as new species. The Cycads and Yews were among the tribes of plants which were continued and increased to a later culmination. Some of the Corals of the Paleozoic belong to the 736 HISTORICAL GEOLOGY. group that is represented among, and make, modern coral reefs. Even the old straight Nautiloid, the Orthoceras, had its later species. The Insects lost, as has been said, a Paleozoic feature at this time ; but the tribes are still the same as before in their more fundamental characters. Pishes, although their period of culmination had passed, still continued under the tribes of Ganoids and Dipnoans. Amphibians and Reptiles held on, and the latter became the ruling life of Mesozoic tin/e. So it was with the greater part of the tribes of the Paleozoic. There was no break in the stream of life, but for the most part only seeming interruptions ; and many of these owe their prominence in geological history to the culminations and declines of types that were in progress. But it was an epoch of relatively abrupt change ; and if chiefly due to the progressive evolution of new species, as has been urged by some geologists, there must have been for the result a great acceleration in such changes in consequence of the physical conditions produced by the orogenic disturbance. But the orogenic movements were local, and the biologically transforming effects from such a cause should have been confined to the countries where these movements were in progress. The universality and abruptness of the disappearances cannot therefore be so explained. Very much is left for the destructive effects, direct and indirect, that is, the exterminations attending the mountain-making. The causes of the exterminations suggested by the changes are two. (1) A colder climate over the land, and colder waters in the extra-tropical oceans ; for the emergence of the eastern semi-continent of North America and of large lands in the other continents could not fail to lower somewhat the temperature of the whole globe. With a lower temperature, the currents from the north sweeping along the coasts would have been destructive to the marine species living in the waters. (2) Earthquake waves produced by orogenic movements. If North America from the west of the Carolinas to the Mis- sissippi valley can be shaken in consequence of a little slip along a fracture in times of perfect quiet, and ruin mark its movements, incalculable violence and great surgings of the ocean should have occurred and been often repeated during the progress of flexures, miles in height and space, and slips along newly opened fractures that kept up their interrupted progress through thou- sands of feet of displacement. The Acadian upturning took place on the ocean's border ; and the Appalachian was not far distant from it. Arkansas, moreover, added to the extent of the belt of disturbance. Under such circum- stances the devastation of the sea border and the low-lying land of the period, the destruction of their animals and plants, would have been a sure result. The survivors within a long distance of the coast-line would have been few. The same waves would have swept over European land and seas, and there found coadjutors for new strife in earthquake waves of European origin. These times of catastrophe may have continued in America through half of the following Triassic period ; for fully two thirds of the Triassic period are unrepresented by rocks and fossils on the Atlantic border. PALEOZOIC TIME CARBONIC. 737 TOPOGRAPHIC CHANGES IN THE INDIAN OCEAN; GONDWANA LAND. The close relations in species of India and South Africa during the Permian and Triassic periods has led to the belief that the two were then connected by a belt of land, and Suess has named the emerged area " Gondwana Land," from the name of the series, including the Permian and Triassic beds, in India. R. D. Oldham remarks (1894) that "the plants of the India and Africa Coal-measures are absolutely identical ; and among the few animals which have been found in the India deposits, one is indistinguish- able from South African species, and another is closely allied; and both faunas are characterized by the remarkable group of Reptiles comprising the Dicynodon and other allied forms." In a map by Neumayr (1885), and its reproduction with some modifications by Oldham, the connecting belt of land extends from India south-southwestward over the Indian Ocean along the range of islands to Madagascar and southern Africa. Among the groups of islands there is the line of the Maldives and the Chagos group ; then, farther west, the Seychelles group heading a line reaching to Newfoundland, and also, to the eastward, a line extending to the Mascarene Islands east of Madagascar. The emerged land makes an off-shore belt for eastern Africa, somewhat like the island range off the shores of eastern Asia, but more continuous. But great depths now exist between the groups. The identity in Permian coal-plant vegetation is as great with Australia as with South Africa. The emerged land, on this evidence, has been supposed by some writers to have covered much of the Indian Ocean. But it is most probable that whatever connection existed for the migration of the plants, it was produced by the spreading of the Antarctic continent northward to a line between the parallels of 35 and 45 S. The absence of the Karoo Reptiles from Australia appears to indicate that the connection with South Africa was not complete ; but it may be that the climate of the northern part of Ant- arctica was not warm enough to favor their migration, while sufficient for that of the plants. Australia also was enlarged ; for Triassic fossil plants from New Zealand and New Caledonia show that these islands, as well as New Guinea, were then included within its limits. The idea that Antarctic land of so great extent became emerged in the Permian era, or about that time, suggests a reason for the existence of evi- dences of glacial phenomena in the Permian of South Africa, India, and Australia. For such a geographical change would certainly have caused a general refrigeration of southern climates ; and if sufficient to produce icy winters and glaciers about high summits, all the observed facts would have their explanation. DANA'S MANUAL 47 III. MESOZOTC TIME. Mesozoic or mediaeval time in the earth's history comprises a single era only. It is the era of the Secondary formations of early geological science, and that of the Reign of Reptiles of Agassiz. It is remarkable as the era of the culmination and incipient decline of three great types in the Animal Kingdom, the Amphibian, Reptilian, and Molluscan, and of one in the Vegetable Kingdom, the Cycadean. It is also remarkable as the era of the first Mammals, of the first Birds, of the first of the Common or Osseous Fishes, and of the first Palms &nd. first Angiosperms. SUBDIVISIONS. 3. CRETACEOUS PERIOD, W. H. Fitton, Ann. Phil, 2d. Ser., viii., 382, 1824. The Chalk Period, or the period of the Chalk formation. 2. JURASSIC PERIOD, A. Brongniart, Tabl des Terrains, 221, 1829, the name referring to the Jura limestone and other related beds of the Jura Mountains between France and Switzerland. 1. TRIASSIC PERIOD, F. v. Alberti, Beitrag Mon. d. bunten Sandsteins, Muschelkalks u. Keupers, Stuttgart, 1834, the name, from the Latin, referring to a threefold division of the formation in Swabia, Franconia, and Lorraine. Variegated sandstone. Buntersandstein, this German name used for part of the strata by Werner. Poikilitic group (Pcecilitic) , Conybeare and Buckland (from the Greek, TTOLKL\O MESOZOIC TIME TRIASSIC AND JURASSIC. 741 Ta., 35 miles long; the Pittsylvania area, farther west in Virginia, 100 miles long, and 40 of the 100 in North Carolina, where it is called the Dan Eiver area ; the Deep River, in North Carolina, east of the Dan Kiver, 145 miles long, the last 30 of them separated by five or six miles from the rest, and distinguished as the Wadesboro area. Leaving out of consideration the Nova Scotia belt, the areas may be viewed as lying in two ranges, an eastern and a western, the Eastern including the Connecticut valley, Richmond, and Deep River areas; the Western, the Palisade, and the Pittsylvania (and Dan River) areas, with the small intervening Buckingham area. The following is a list of the areas : (1) The Acadian area, along the west margin of Nova Scotia (or the northeast border of the Bay of Fundy), having a course nearly northeast to the south, but with much east- ing to the north ; and bending to east and west along the Minas Basin (its north side). (2) The Connecticut valley belt, from northern Massachusetts to New Haven Bay, this bay being the southern termination of the valley. (3) The Southbury belt, 15 miles west of the Connecticut valley in Connecticut, only 8 miles long and 2J wide. (4) The Palisade area, commencing near Haverstraw on the Hudson, 30 miles wide in New Jersey, 12 on the Susquehanna, and 6 to 8 on the Potomac ; and including a small area in Orange, Va., which was probably separated by erosion. (5) The Buckingham area, farther south, on James River, 18 miles long and 2 wide. (6) The Richmond area. (7) A small Hanover area, a few miles north of the Richmond, but probably a former part of the Richmond. (8) The Cumberland area, 30 miles west of the Richmond and mainly in Cumberland County, 22 miles long. (9) The Pittsylvania area, including the Dan River of North Carolina. (10) The Deep Eiver area of North Carolina, commencing at Oxford in Granville County, passing west of Raleigh, and having a width of 18 miles. A Triassic area has been supposed to exist on Prince Edward Island, in the Bay of St. Lawrence, and is so described by Dawson in his Acadian Geology. According to R. W. Ells, the beds are part of the Permian of the island, with which they are conforma- ble (1883-84). Bain has since claimed as Triassic the upper 50 feet, horizontal in position, occurring on the north shores of the island, near New London (1885) ; and Dawson states in an appendix to his work (dated 1891), that the strongest evidence of Triassic age for this part of the sandstone is the presence in it of Bathygnathus borealis of Leidy. Marsh, in a private note to the author, confirms this view of Dawson, stating that Bathygnathus, a carnivorous Dinosaur, is very much like the Triassic forms of England, Germany, Asia, and Africa. 3. Hocks. The rocks are mostly : granitic sandstones (a much better name for them than the meaningless term arkose) ; conglomerates, varying from fine pebble beds to those consisting chiefly of cobble stones and larger rounded masses; sandy shales ; less commonly fine black carbonaceous shales; occa- sionally thin beds of impure limestone ; and, in some localities, bituminous coal in thick beds along with carbonaceous shales. In general, the formation is well stratified ; but the strata, when followed laterally, vary much in thickness and coarseness. In some places borings 742 HISTORICAL GEOLOGY. have gone down 3000 feet through sandstone alone ; and seldom are the inter- calated beds of limestone and shale of sufficient extent to mark a horizon and serve as the means of measuring the thickness. At New Haven, Conn., an artesian boring was carried down 4000 feet through porous sandstone without finding variation enough in texture to get a supply of water. The layers often have a cross-bedded structure and other evidences of strong currents. In many regions they are here and there covered with ripple-marks, mud-cracks, raindrop impressions, footprints of Reptiles and Amphibians ; the fine shales with tracks of Insects and Crustaceans facts which indicate temporary exposures above the water level of great sand-flats and mud-flats. A slab from Greenfield, Mass., a dozen feet long, now in the Yale Museum, is covered throughout with deep impressions of raindrops the work of a short large-drop shower. The impressions are a little elliptical so as to register the direction of the accompanying wind. Besides this, two lines of large three-toed tracks cross the slab, and those of the longer line are dotted by the raindrops, showing that a biped reptile had passed that way before the shower began. The material of the sandstones and conglomerates, exclusive of the calcareous, is almost solely such as would be afforded by the wear of granite, gneiss, mica schist, syenyte, and other crystalline rocks of the neighboring hills or mountains ; and the amount of mica and other ingredients and kinds of rock material vary with the kind of rock in the adjacent hills. Several examples of this are mentioned by Emerson, Fontaine, and others. The feldspar is usually fresh and undecomposed, and well mixed with the quartz, showing no evidence of any assortment of the ingredients by beach action. The ingredients are often in proportions fitted to make granite again by subjection to metamorphic action. Mica is sparingly present except where mica schists exist on the border of the areas. There are also limestone con- glomerates in regions where Cambrian or Lower Silurian rocks exist along the border ; and occasionally stones of a quartzose conglomerate derived from a Cambrian sandstone or quartzyte. The coarsest conglomerates consist of stones of all sizes up to five feet across, and usually occur along the eastern or western border of an area. In Montague, Mass., east of the Connecticut, on the eastern border of the area, and in Branford, Conn., some of the bowlders are three feet across. Similar cases exist on the west border of the western area in New Jersey, Virginia, and North Carolina. In the Pittsylvania belt, the larger stones are four to five feet in diameter. Near Point of Rocks, Md., the stones are of Paleozoic limestone, and some are two feet through ; the finer variety of this limestone conglomerate is the " Potomac pudding-stone marble." The Coal-measures in the Richmond basin and Virginia, and in North Carolina, consist of beds of shale and sandstone with thick beds of good coal. In the Richmond area there are two to eight coal-beds, and the main bed is 10 to 40 feet thick ; but they include some thin dividing layers of sandstone and shale. The Coal-measures are situated within 250 to 500 feet of the bottom MESOZOIC TIME TRIASSIC AND JURASSIC. 743 of the formation ; and the same is true of those of the Deep Eiver and Dan River areas in North Carolina. The Connecticut valley area has some carbonaceous shale, but no coal. On the Virginia belts and the Richmond coal areas, see Fontaine in Am. Jour. Sc., 1879, and U. S. G. 8., Memoir, 4to, 1883; on those of North Carolina, Emmons's Geol. Eep. of North Carolina, 1856, and Kerr's Hep., 1875. Also, for a general review of the Triassic, the Correlation report of I. C. Russell, Bull. U. S. G. S., No. 85, 1892, which contains colored maps of the areas. Besides the sandstones and other rocks of aqueous origin, there are in the several areas rocks of igneous origin. These are described beyond (page 800). The thickness of the Triassic formation in the several areas is deter- mined with difficulty, not only on account of the want of continuous easily recognized strata to mark horizons, but also because of the many con- cealed faults and the upturned condition of the beds, as explained beyond. The maximum may be, in some of the areas, 8000 to 10,000 feet. In the Richmond area, Virginia, the thickness has been made 2000 to 2500 feet. In North Carolina, in the Deep River area, according to Emmons, it is 3000 feet. Much larger estimates have been made. On the southern border of New York, in Rockland County, at Ramapo, near the northwestern limit of the Triassic beds, the thickness, down to the underlying gneiss, was found in a boring to be 120' (J. C. Smock). The large estimates are obtained by calculation from the dip, and the width at right angles to the dip. By this very unsatisfactory method a thickness of 12,000' to 25,000' has been obtained. Kerr thus arrived at a thickness of 10,000'. for the beds of the Dan River area, North Carolina, and 25,000' for those of the Deep River area. In New Jersey and Pennsylvania, according to B. S. Lyman, there is a long longitudinal fault of 14,000'. 4. Sources of the material and conditions of accumulation. So large a num- ber of independent belts of sandstone ranging along for 1000 miles is an un- usual feature for a Continental border. It is not possible that the sandstone formation was made during a general submergence, and in a great common body of water ; for there is nothing marine about it in fossils or in structure ; and fresh waters for the work could not have spread over the region of hills, ridges, and valleys, under any probable circumstances. Moreover, the Nova Scotia belt occupies the same Acadian trough which received deposits through Paleozoic time, even to the Carboniferous and Permian ; and the Con- necticut valley belt is in the same trough which had Silurian and Devonian beds laid down in its northern half, and possibly also in its southern half, for in this part the Triassic formation conceals what is below. Further, the parallelism of the belts to the mountain ranges of the Continental border is close, the Palisade trough taking faithfully their bends, from south by west on the Hudson River, to west-southwest in Pennsylvania (see map, page 731), and southwest in Virginia, as if occupying orographic valleys of the Appalachian Mountain chain. The facts show that the courses of the 744 HISTORICAL GEOLOGY. areas were determined not mainly by fluvial action, nor by a great sub- mergence, but by the topography of the Continental border as it existed immediately after the Appalachian upturning. \ It is plain that some of the areas were marsh regions along the courses of streams and lakes ; and two or more may have been estuaries, like the Chesapeake or Delaware Bay, receiving the tides during part or all of their history. But it is also proved by the deposits that the broad streams sometimes were great streams, making conglomerates where the water had great velocity, sandstones in gentler currents, shales in the sluggish waters, and beds of vegetable debris, for a coal-bed, where the conditions were those of a great marsh. As in other fluvial regions, conglomerate-beds, sand-beds, and mud-beds may have been forming simultaneously at the same horizon in different portions of an area. Moreover, under fluvial action, different kinds of deposits in flowing waters would be lengthened out in the direction of the flow, making unlike formations, longitudinal with the stream, of parallel position and history, looking, to one traversing the surface, or studying the exposed beds, like consecutive formations. If a region were slowly sub- siding so that the beds could thicken, there would probably be, in a portion having like velocity throughout, four or five rather prominent kinds of de- posits, one made along the bed of the stream ; two others along the banks ; two others beyond the banks on either side ; and each of these would have their local belts. These and other sources of diversity existed in the Trias- sic areas. Where were the sources, and what the directions, of the rivers over the higher lands from New York to North Carolina, which supplied so generally granitic sediments instead of quartzose sands and fine clays, are questions not easily answered. The recently made Appalachian Mountains stood along the western side of the Archsean protaxis, and these Triassic formations on the east side. It would seem to be a necessary consequence that the Appalachians should have sent off streams eastward to the Atlantic and loaded the waters with Appa- lachian sands and other detritus. But it is proved, by the prevailing granitic character of the material of the sandstones, that little if any of these sedi- ments reached the Triassic troughs, either from the Appalachian Mountains of Virginia and Pennsylvania, or from the plateau region of Pennsylvania and the Catskills the present sources of the mud, sand, and water of the Dela- ware, Chesapeake, and other streams ; that the Archaean protaxis was so high and continuous as to wholly prevent drainage from the west and northwest ; that this range of crystalline rocks and the ridges of more or less crystalline Cambro-Silurian, of the region in the vicinity, supplied the streams with sediments for transportation to the Triassic areas. The drainage from the Appalachian Mountains must have flowed westward or southwestward. The river or waters of the time flowing southward just west of the site of New York City where now flows the Hudson were 25 miles wide, as the breadth of the Triassic of the region shows ; and they had sources evidently MESOZOIC TIME TRIASSIC AND JURASSIC. 745 in the nearer mountains to the north, west, and south. These sources were probably in the Highlands and other ridges of crystalline rocks ; the waters and sediment certainly did not come from the Catskill Mountains to the north, nor from the Alleghanies to the west. The outlet of the Hudson Eiver of the period to the Atlantic is indicated, apparently, by the submerged Hudson River channel on the map on page 18. The barrier along the sea margin that kept out salt water and its living species was evidently the remains of the old geanticline referred to on page 387. The coarse conglomerate at or near the top of the sandstone series, observed at many points on the east margin of the Connecticut valley area, and on the west or inner margin of that of Maryland, Virginia, and North Carolina, in which many of the rounded stones are one to three feet in diameter, and also the similar large stones, or groups of stones, occurring isolated in some of the finer sandstones, are remarkable features of the forma- tion. Rivers cannot transport so large bowlders, unless down rapid slopes. The tide in an estuary opening seaward only moves quietly, and usually makes muddy or sandy shores. Igneous eruptions are never attended by ejections of rounded stones or bowlders. The stones, excepting those of Triassic sandstone and trap, show by their kinds that they were from the adjoining ridges or hills. Moving ice would carry them; but the Blue Ridge and other adjoining ridges at the present time are far from high enough to have glaciers about their summits. The question arises : Were they high enough then ? Was there, at or near the close of the period, an epoch of unusual cold having icy winters and covering the adjoining ridges with glaciers that carried bowlders, and made streams that bore floating ice laden with stones out over the river or estuary waters ? 5. Subsidence in progress during the deposition. Since a thickness of some thousands of feet was acquired in the several areas by the strata, and the beds often bear evidence in their ripple-marks, mud-cracks, and foot- prints of shallow-water origin, each of the troughs of valleys must have been undergoing, during the slow accumulation, a concurrent subsidence of as many thousands of feet. On the upturning of the beds and other orographic phenomena see page 798. Economical products. The coal-beds, already described, are a prominent part of these products. Veins containing copper ores occur in Connecticut, New Jersey, Pennsyl- vania, which have been worked ; but none are now producing ore. The copper ores are chiefly chalcocite and bornite, with occasionally native copper. One mass of native copper found in the drift north of New Haven, Conn., weighs nearly 200 pounds. A copper mine at Bristol, Conn., which was for awhile productive, is situated on the western border of the Triassic, in the crystalline rocks outside of the sandstone area, but belongs to a fissure of the Triassic series. Barite often accompanies the ore, and sometimes is the chief mineral of the vein, and occasionally occurs in crystals weighing over 100 pounds. A vein in Cheshire, Conn., now exhausted, yielded a large amount of the mineral for the adulteration of white lead, and for calsomining and other purposes. The beds of sandstone afford much rock for building purposes. The rock so used is 746 HISTORICAL GEOLOGY. often called brownstone. The material of many of the "brownstone fronts" of New York and other eastern cities is mostly from this formation. The Potomac conglomerate marble is used as an ornamental stone, and columns of it stand in the Capitol at Washington. 2. The Triassic and Jurassic of the Western Interior and Pacific Border Regions.. The Triassic and Jurassic formations of the Western Interior and of the Pacific border have a wide distribution, and, to some extent, distinguishable limits. The former consist almost everywhere, in the Interior, of reddish sandstones and marly tes, and are often called " Red Beds." They frequently contain gypsum and sometimes salt. Upon the Pacific Ibrder the rocks of this period are chiefly slates, with occasional sandstones, and much limestone. The Jurassic beds are usually of lighter shades of color, and are in most regions partly or chiefly calcareous, and the limestone is often cherty. A large part of the Triassic formation is without fossils, excepting occasional traces of plants; but the Jurassic is often fossiliferous, though seldom prolific in species. Triassic. Over the Continental Interior, the Triassic formation is exposed to view in northern Texas, adjoining Indian Territory and western Kansas. The beds probably underlie the Cretaceous beds farther northward, but no out- crops occur in that direction except in mountainous regions to the west and northwest. They exist about the Black Hills of Dakota, and cover large areas along the Summit Region of the Rocky Mountains in New Mexico, Colorado, and Utah, east of the western limit of the Wasatch Range, and also in Wyoming, Montana, and Idaho. In British America, east of the Archaean protaxis, they have been observed on Peace and Pine rivers, beyond 55 N. and between 122 and 125 W. ; and also on Liard River, near 59 N. Beds in southeastern Idaho, near Soda Springs, have been referred to the Lower Trias (Mojsisovics, Hyatt) ; but the absence or non- discovery of fossils leaves the age of the beds of the Rocky Mountains and Interior Continental regions generally undetermined. West of the meridian of the Wasatch Mountains, and of the Rocky Moun- tain protaxis in British America, over the Great Basin plateau, and its con- tinuation in the plateau region of British Columbia, the Trias appears to have a wide range. In the United States it is confined to the west side of the plateau or Great Basin beyond 1171 W., on the 40th parallel. In the west Humboldt region, according to King, 15,000 feet of beds, partly Middle Trias, underlie 4,000 feet or more of Jurassic beds. In the plateau region of British Columbia, Triassic areas occur on Nicola Lake (50 N., 1201 W.) and Stikine River (57 K, 1371 W.). Farther west, in the Sierra belt, beds of the Upper Triassic occur near the summit of the Sierra Nevada in Plumas County, Cal., as first identified MESOZOIC TIME TRIASSIC AND JURASSIC. 74T by Gabb from fossils discovered during the Whitney Geological Survey (1864), and later studied over the Taylorville region by Diller and Hyatt (1892). The thickness of the Triassic in this region is about 4800 feet, and of the overlying Jurassic sandstones, limestones, and tufa about 2000 feet. The formation is continued northwestward into the Klamath Mountains. Whether it exists in the Cascade Range still farther north is unknown, as these mountains are mostly under recent volcanic rocks. The Island belt in British Columbia contains areas of Upper Triassic on Vancouver Island, Queen Charlotte Islands, in the Straits of Georgia; and beyond they occur at Wrangel Bay, Alaska. Upper Triassic -beds occur also in Mexico, in the states of Sonora (New- berry, 1876), Puebla and Oasaca (Aguilera and Ordonez, 1893). They are found also in Honduras (Newberry, 1888). In the Black Hills, the Triassic beds, or the "Red Beds" supposed to be Triassic, come to the surface, along with the Jurassic, from beneath the Cretaceous beds of the Continental Interior, as first shown by Meek (1858, 1860). They are mainly arenaceous clays, unfossiliferous, 300' to 400' thick, with 15' to 30' of impure limestone below the middle, and with gypsum in the upper half. In the foot hills east of the Front Range in Colorado, the Triassic and Jurassic often appear overlying the Archaean, or the Paleozoic* 600' to 1000' of the former, to 200' or 300' of the latter. In these foot hills, to the west- ward, within 30 miles of the line of New Mexico, and for 50 miles beyond, as stated by Stevenson, the Cretaceous rests on the Carboniferous over Archaean, the Triassic not extending so far west. Bordering the Laramie Plains, in Wyoming, these formations may be seen over Archaean ; the gypsum beds of the Triassic are sometimes over 20' thick. In Idaho, north of the Wasatch, between the Wyoming and Portneuf ranges (HOJ - 112 W.), upturned Triassic and Jurassic beds, according to A. C. Peale (1879), enter largely into the structure of the ridges ; and these formations in the Blackfoot Basin, where the Triassic is about 4000' thick and the Jurassic 1500' (more than half limestones), afforded the fossils described by C. A. White in 1879 (page 758). In the Wasatch there are 1000' to 1200' of Trias overlaid by 1600' to 1800' of Jurassic beds (King). In the High Plateaus to the south, north of the Colorado Canon, the "Vermilion Cliffs" of Powell, 1000' to 1500' high, which extend for 100 miles from Hurricane fault to Paria, and the " Shinarump Cliffs" below, are Triassic, while the overlying " White Cliff group," 2000' or more thick, consisting of white sandstone and calcareous beds, and the " Flaming Gorge group " in Utah, are referred with some doubt to the Jurassic. The beds are con- tinued southward in plateaus of Arizona and New Mexico. The Trias of western Nevada consists, according to King, of a lower Koipato group of siliceous and argillaceous beds, 5000', and above this, great limestone strata and alternating quartzyte of the Star Peak groups, 10,000'. The Trias of this region may have once been connected with that of the Sierra Nevada just west. Upon the northern end of the Sierra Nevada, near Taylorville, Diller measured nearly 5000' of Upper Trias. It lies apparently unconformably upon both sides between the Jurassic and Carboniferous. It consists below of 200' of slates overlaid by 140' of limestone, and above of over 4000' of sandstones and slates. In the two lower members fossils are often abundant, but in the upper slates they are rare and chiefly land plants. The limestone is most persistent, and has been recognized by its fossils near Pit River and elsewhere in the Klamath Mountains, and even as far north as Siskiyou County, near the Oregon line. The presence in that region of large masses of eruptive material, often fossiliferous, shows 748 HISTORICAL GEOLOGY. that volcanic forces were vigorously active, not only\during a portion of the later Trias, but also in the earlier Carboniferous and later Jurassic. The Trias was first recognized as existing probably in Sonora, Mexico, by A. R6mond (J. D. Whitney, Am. Jour. Sc. t 1866). He speaks of it as consisting of sandstones and conglomerates with coal-bearing clay shales. He adds that the metamorphic slates of the Altar and Magdalena districts, which include the richest gold placers of Sonora, may possibly be of Triassic age, but that it is also possible that they are Jurassic, as they resemble rather the Jurassic gold-bearing slates of the Sierra Nevada." Jurassic. Jurassic beds are found at the west base of the Black Hills in Dakota, where the rock is limestone with intercalated marls. The thickness, 200 feet, increases to 600 feet 40 miles from the Hills (Newton), indicating, as W. 0. Crosby implies, less subsidence in the sea-bottom about the Archaean center than at a distance from it. They also come out to view at points along the base of the Laramie Mountains, the Big Horn Mountains, the Wind Biver, and other mountains in the Bocky chain. They overlie Triassic through much, of the Summit Begion within the United States, both east of the Great Basin or Plateau belt, and, as has been mentioned, along its western border beyond 117|. Farther north in the same belt, they have been observed by Diller on the Blue Mountains of Oregon. The Upper Jurassic in Colorado, Wyoming, and Montana includes the freshwater Atlantosaurus beds of Marsh, from 100 to 300 feet thick, which, have afforded, near Morrison and Canon City in Colorado and elsewhere, the remains of many large Beptiles, teeth and jaws of Marsupial and Oviparous Mammals. The Baptanodon beds of Marsh, when present, are next below. They contain remains of large aquatic Beptiles, besides some marine inverte- brate fossils. The Jurassic beds are found along a large part of the western slope of the Sierra Nevada. The first discoveries were made in Plumas County, on the north slope of Genesee valley, by Clarence King, of the Whitney Survey, in 1863. They were afterward discovered in the auriferous slates of the Mariposa region and identified by fossils (Gabb, 1864; Meek, 1865). In the Taylorville region in Pluinas County, the Jurassic beds, according to Diller and Hyatt, are found to consist of nearly 1500' of sandstones, 10' to 30' of limestones, and 500' of tufa. The series represents, as Hyatt has found from the fossils, the Lias and the Lower and Upper Oolyte. The Upper Oolyte has also been identified by fossils over a wide range of the western slopes of the Sierra, where the rocks are upturned metamorphic slates, hydromica, mica, and siliceous schist, with sandstone, and in some parts, serpentine, and thin beds of crystalline limestone, besides more coarsely crystalline rocks. The belt of slates which is in general 20 to 25 miles wide contains the chief part of the gold- bearing veins of quartz, some of which are of great width. Turner describes the Mariposa slates as including much diabase tufa, besides some conglomerates made of siliceous pebbles from the associated rocks (1894). The most abundant fossil in the Mariposa beds is a species of Aucella (see beyond, page 760), and hence related beds have been called Aucella beds. The Mariposa rocks were pronounced Jurassic by Gabb (1864) and Meek (1865), and recently also by Hyatt. MESOZOIC TIME TBIASSIC AND JURASSIC. 749 The Lias and earlier Oolyte appear to be unrepresented along the Coast region and Plateau belt of British America (G. M. Dawson). Jurassic beds, related in fossils to those of Taylorville, occur also in the Pit Kiver region on the western and northern borders of the Sacramento valley, with Triassic and Carboniferous below, and are covered unconf ormably by the Cretaceous ; also on the upper waters of Crooked Kiver, in the Blue Mountains of Oregon ; and, according to Hyatt,, these areas were connected, during the Lias, with that of western Nevada. Small Jurassic areas are laid down on Castillo's geological map of Mexico, in the states of Sonora, Coahuila, San Luis Potosi, Queretaro, Hidalgo, Puebla, and others near the east- ern border of the great central plateau, and also in Colima near the coast. The beds, according to Aguilera and Ordonez (1893), contain Aucellse, and Ammonites of the genus. Perisphinctes, and pass conformably into the overlying Cretaceous. In the Arctic Regions, the Jurassic (Lias ?) has been identified far north on Prince Patrick Island and near the northwest extremity of Bathurst Island, and on Exmouth Island and other places in the vicinity. At the locality on Bathurst Island, a vertebra of a Saurian, Arctosaurus Osborni, has been found ; and on Exmouth Island, remains of an Ichthyosaurus. The Jura-Trias regions of part of Utah and Nevada are mapped (in colors) in King's 40th Parallel Report (1878); and of Idaho and part of Utah, by Peale, Endlich, and St. John, in the Hayden Expedition Report for 1878 ; and of part of California by Diller (1893) in the Atlas of the U. S. Geological Survey, on the sheets of the Lassen Peak district. 1156-1160. 1157 Fig. 1156, Podozainites Emmonsi; 1157, Pterophyllum Riegeri; 1158, Clathropteris rectiuscula; 1159, Oligo- carpia (Pecopteris) robustior, part of a frond in fructification ; 1160, Tseniopteris linnseifolia. Figs. 1156- 1169, E. Emmons ; 1160, E. Hitchcock, Jr. 750 HISTORICAL GEOLOGY. LIFE. 1. Triassic of the Atlantic Border. PLANTS. The vegetation of the Triassic was characterized not by Sigillarids and Lepidodendrids, like that of the Carbonic era, but by Cycads, Conifers, Ferns, and Equiseta. As the Cycads were a prominent feature of the forests in both the Triassic and Jurassic periods, a figure of a common East India species, Cycas circincdis ( X Y^) is given on page 434. Its relation to Conifers, both groups being G-ymno sperms, notwithstanding its palm-like foliage, has already been explained. Portions of leaves of two species related somewhat to the modern Zamia are represented in Figs. 1156 and 1157. Conifers existed of the genera Voltzia (differing little from Walchia of the Permian, page 705), Baiera, and Araucarites. Stems, leaves, cones, and trunks of such trees are not uncommon. Ferns were numerous, of the genera Pecopteris (Fig. 1159), Tceniopteris : (Fig. 1160), Clathropteris (Fig. 1158), and others related. Some of the Equiseta (Calamites) had a breadth of stem of four inches or more. ANIMALS. The Triassic beds of the Atlantic border have afforded no marine species of any kind; all are 1 "I f\Q either of fresh or brackish waters, or else terrestrial, lies 1. Crustaceans and Insects. The Crustaceans observed are mostly Ostracoids. The little shells (Figs. Figs. H61-1163, Estherta ovata. Fig. 1161, Lyeii; H61-1163) are abundant in some 1162, E. Emmons ; 1163, L. Sanford. beds oi shale. The presence of Insects is known from their tracks and from the discovery of the larves of one species. These larves (Fig. 1164) were found by E. Hitchcock rather abundantly in shales at Turner's Falls, and have since 1164-1169. 1164 1165 f\ 1166 Lb7 I 1168^ ^ \ 1169 A r ( > u v v * ' ^' w \ ^ \ s\ P\ \l \J \ fir l *N y'V U U U M \l W N . /\ ,. I/ \ ' V| \J v ^ \ INSECTS. Fig. 1164, Insect larve, Mormolucoides articulatus ; 1165-1167, tracks of Insects; 1168, 1169, tracks of Crustaceans (?). Fig. 1164, from Scudder ; 1165-1169, E. Hitchcock. been obtained at Montague, and at Horse Race in Gill, Mass. The Insect was a Neuropter. Figs. 1165 to 1167 are of tracks from the Connecticut MESOZOIC TIME TRIASSIC AND JURASSIC. 751 valley beds, referred by E. Hitchcock to Insects, and the others (1168, 1169) are regarded by him as made by Crustaceans. Nearly 30 species of these delicate tracks are described by Hitchcock. 2. Fishes. The Fishes of the era were Ganoids and Sharks, but only remains of Ganoids have been found in the American rocks ; one of them, from black shales at Durham, Conn., is represented, reduced, in figure 1170. The largest species found is Diplurus longicaudatus Newb., about three feet long. Unlike Paleozoic Ganoids, the Triassic species are not all heterocercal ; many have the tails partly, or not at all, vertebrated; and this is the last period in which the old Paleozoic characteristic appeared. Thus, as Agassiz first observed, the progress of the ages was marked in the tails of the fishes. 1170. 1171-1172. 1171 1172 GANOID. Catopterus gracilis (x $). J. H. Kedfield. 3. Amphibians. Portions of large crania have been found in black shale in Chatham County, N.C., and in a literal " bone-bed " at Phoenixville, Pa. With the latter were teeth two inches long, of a spe- cies named Eupelor durus by Cope. The figures of footprints annexed, 1171, 1171 a, and 1172, 1172 a (half to two thirds the natural size), are the fore and hind feet of probably two Amphibians (Hitchcock). The tracks were from the Connecticut valley beds. 4. Reptiles. The Reptiles pertain to the two grand divisions of Dinosaurs and Crocodilians. Dinosaurs. The Dinosaurs are mostly of large size, and were so named by Owen, from Setvds, terrible, and o-avpos, lizard. They are more or less bird-like in some characteristics ; these all having (1) the posterior limbs the stouter, as in Fig. 1179, page 753, and some- times these are the only locomotive limbs, the Reptiles in that case being bipeds in walking, like birds; (2) the bones of the limbs, especially the anterior, often hollow ; and in some, the vertebrae of the neck very cellular and light ; (3) of the pelvic bones the ischium (is, Fig. 1179) is a long and often slender bone projecting backward, and the pubes also are long. Many herbivorous Dino- saurs that were not biped in locomotion used their strong hind limbs for 1172 a AMPHIBIANS. Fig. 1171, 1171 a (x ), Amsopus Deweyanua ; 1172, 1172 a, A. gracffls (x |). E. Hitchcock. 752 HISTORICAL GEOLOGY. holding their bodies raised against trees or other objects; and hence there- was great convenience in having the bones of the anterior part of the body cellular and thereby light. 1173-1177. 1178. DINOSAUBIANS. Fig. 1173, Macropterna divaricans (x $); 1174, Apatichnus bellus (x $); 1175, Anomoepu& scambus, fore foot (x J); 1175 a, hind foot of same ; 1176, Otozoum Moodii, fore foot ; 1176 a, hind foot of same (both x^) ; 1177, Brontozoum giganteum (x). All from Hitchcock. The track represented in Fig. 1177 occurs from 14 to 18 inches in length, and was made by one of the biped Dinosaurs ; it is the Brontozoum giganteum of Hitchcock. The tracks 1175, 1175 a, also much reduced, are of another bird-like Dinosaur, but one that had three-toed feet behind (1175 a), and a small four-fingered hand in front that was only occasionally brought to the ground. The track 1176 a r 20 inches long natural size, is of the hind foot of an Otozoum, a gigantic Dinosaur that usually walked erect, biped-like ; its much smaller fore feet (1176) served as hands, for they were seldom brought to the ground. The stride of the Otozoum was a yard in length. The other lines of tracks, 1173 and 1174, are of species that walked on all fours. These tracks indicate three kinds of Dinosaurs : (1) bipeds with the hind feet 3-toed ; (2) bipeds with the hind feet four- Blab of sandstone, with footprints. Hitchcock. toed; (3) quadrupeds walking on all fours. A slab of sandstone, with its footprints in several series, is represented in MESOZOIC TIME TRIASSIC AND JURASSIC. Fig. 1178; it is reduced to ^ the natural size, excepting the two tracks lettered a, which are enlarged views of the tracks of the line b. No tracks of fore feet have been found with them, and hence it is thought possible that some are tracks of Birds. But no positive evidence of Birds has been found. The collection of Amherst College, and that of Yale at New Haven, contain each several thousands of tracks from the Connecticut valley ; a fact that gives some idea of the abundance of life on the continent in Triassic time. Other estuaries and valleys besides those now occupied by Triassic beds were probably equally populous. Twenty-one consecutive tracks of the Otozoum were exposed to view in 1874, at one of the quarries at Portland, Conn. Bones of the Dinosaurian Reptiles were first found in 1818, in the sand- stone of East Windsor, Conn., and near Springfield, Mass. ; and the foot of one 1179. from the latter locality was figured in 1865 by Hitchcock, who (in allusion to the length of the bones) named the species Megadactylus polyzelus; and in 1870 the Reptile was described and pronounced a Dinosaur by Cope. Remains have since been discovered in North Carolina, Pennsylvania, and Prince Edward Island, and again in Connecticut. Near Manchester, Conn., large portions of four skeletons of the same genus, and of another, Ammosaurus, have been obtained by Marsh. Fig. 1179 represents a restoration published by him in 1893. The name Megadacty- - lus being preoccupied, it is changed by him to Ancliisaurus. It was one of the car- nivorous Dinosaurs that left tracks on the sandflats and mudflats of the Connecticut valley estuary. Fig. 1179, restoration of Anchisaurus colurus Marsh (x^). p, pubis ; w, ischium ; /, femur. Other Dinosaurs are : Clepsysaurus Pennsylvanicus of Lea, from Phoenixville, Pa., Fig. 1181 ; Bathygnathus borealis of Leidy, from Prince Edward Island, DANA'S MANUAL 48 754 HISTORICAL GEOLOGY. a tooth of which, from a skull described and figured by him, is represented half the natural size in Fig. 1180; the 1180-1183. 1182 teeth were four inches long; also, ii8i L82a j& Palceoctonus Appalachians Cope, from Phcenixville ; an anterior tooth having a length of 3J inches ; also Thecodon- tosaurus gibbidens Cope, Palceosaurus Fraserianus Cope, Suchoprion aulacodus Cope, from Phoenixville. Crocodilians. The Crocodilians are Thecodont species (that is, have the teeth in sockets). They pertain to the genus Belodon, and are characterized by the Palaeic features of biconcave verte- brae ; the jaws were long and slender, like those of the Gavials. Teeth of two species are represented in Figs. 1182, 1182 a, Belodon prisons of Leidy, and Fig. 1183, B. Carolinensis of Cope, from Pennsylvania and North Carolina. Bones of one species have been found by Marsh in the Connecticut sandstone. Coprolites are common in the shales at Phoenixville, Pa. 5. Mammals. The only Mammalian remains of the Atlantic border are two jaw-bones, found in Chatham County, K C., by E. Emmons. They belong to 1184-1185. 1184 a DINOSAURS. Fig. 1180, Bathygnathus borealis; 1181, Clepsysaurus Pennsylvanicus. CEOCODILIANS. Fig. 1182, tooth of Belodon priscus ; 1182 a, section of same ; 1183, B. Carolinensis. Fig. 1180, Leidy; 1181-1183, E. Emmons. 1185 a MARSUPIAL MAMMALS. Fig. 1184, Drornatherium sylvestre (x3); 1184 a, id. (x 1) ; 1185, Mtcroconodon tenuirostris ( x 4) ; 1185 a, id. (x 1). Osborn. Insectivorous Marsupials, Dromatherium sylvestre of Emmons, and Microco- nodon tenuirostris of Osborn.* Mammals of similar character probably spread over the continent, and may have been of many species. *Owen says of the Dromatherium that " this Triassic or Liassic Mammal would appear to MESOZOIC TIME TRIASSIC AND JURASSIC. 755 Characteristic Species. PLANTS OF THE EASTERN BORDER TRIASSIC. For figures and descriptions of Virginia and North Carolina plants, see Fontaine's Report, containing 53 plates, which contains also the figures in Emmons's N. Car. Eep. of 1853, and in his American Geology ; also, for those of other localities, Newberry, U. S. G. 8., 4to, 1888. The plants are referred to the Upper Triassic by Fontaine, Newberry, and L. F. Ward. D. Stur, of Vienna, after a study of the figures and specimens, concludes ( Verh. G. Reichsanst., 1888, and Am. Jour. Sc., xxxvii., 1889) that over a dozen of the Virginia species are identical with Austrian plants from the Lettenkohle or Lower Keuper of Lunz and other European localities. Fontaine states that the plants collected in Virginia are mostly from the Richmond Coal-measures, and therefore from the lower part of the Triassic formation, while those of North Carolina are from a higher horizon ; and that a number of species from the latter region are related to the Rhsetic of Europe, and 2 are probably identical with species of the Lias. According to Newberry only 6 to 8 of the few species of New Jersey and the Connecticut River valley are identical with those of Virginia. The black shale of Durham, Conn., has afforded 5 of these species. He also states that several North Carolina species are found at Abiquiu in New Mexico, and Los Bronces in Sonora, Mexico, rendering it probable that the beds are alike Upper Triassic. Dawson has described Dadoxylon Edwardianum and Cycadeoidea Abequidensis, from Prince Edward Island. ANIMALS. Footprints appear to have been first critically observed in the Connecticut valley by J. Deane of Greenfield, Mass., in 1835, and made known by him to E. Hitchcock. The latter in 1836 began his extended collection and study of the footprints, and his publications thereon; .first in 1836, of 7 species (Am. Jour. /Sc.), and later in his Hep. Geol. Mass., 1841, and his Reports on Ichnology in 4to, of 1848 and 1858 and 1865. He first made all 3-toed tracks ornithic ; but later proved this erroneous by finding impressions of the fore feet. In 1837, discoveries were made in Connecticut by William A. Redfield, and later others in New Jersey and Pennsylvania. Deane pub- lished papers in 1844, 1845, and later ; and a posthumous volume on Ichnographs, from his notes, by T. T. Bouve, appeared, in 4to, in 1861. See also publications of Boston Soc. N. Hist, for many papers by different authors. For descriptions of the Reptiles see Hitchcock, loc. cit. ; Emmons, loc. cit. ; Wyman, Am. Jour. Sc., 1855; Leidy's papers in the publications of Acad. Nat. Sc. Philad., 1854 1186. Fig. 1186, Myrmecobius fasciatus (x |). find its nearest living analogue in Myrmecobius, for each ramus of the lower jaw contained ten molars (premolars included) in a continuous series, one canine and three conical incisors, the latter being divided by short intervals." 756 HISTORICAL GEOLOGY. and later; Marsh, in Am. Jour. 8c., since 1875 ; Cope in publications of Acad. Nat. Sc. Philad., Amer. Phil. Soc. and Amer. Naturalist, since 1864. On Fossil Fishes, John H. Redfield, Ann. N. Y. Lye. N. Hist., 1836 ; William C. Redfield,. Am. Jour. Sc., 1838 to 1843 ; Newberry, U. S. G. S., 4to, 1888, with figures of the species. On the Mammals, E. Emmons, loc. cit. ; H. F. Osborn, Acad. Nat. Sc. Philad., 4to,. 1888, and also in later papers ; R. Owen, Pal. Soc. London, 1871. 2. Triassic and Jurassic of the Western Interior and Pacific Border Regions, Triassic Formation. The Trias of the Western Interior and Pacific border regions, although of great thickness, has afforded few organic relics of any kind. PLANTS. The following are figures of three species of Cycads from the Upper Triassic (B/hsetic) of Honduras, described by Newberry (1888). At the Abiquiu Copper Mines, New Mexico, Newberry obtained (San Juan Eep.) the new species Otozamites Macombii (also from Sonora), and Zamites 1187 1189 CYCADS. Fig. Ils7, Anoinozamiteselegans ; 1188, Otozamites linguiformis ; 1189, Encephalartos (?) denticulatus. Newberry. occidentalis. Sonora, Mexico, has afforded Newberry species of Pecopteris (Oligocarpia) , Alethopteris, Camptopteris, Tceniopteris, including the Virginia species Tmniopteris magnifolia (T. latior Star), and also a Jeanpaullia, J. radiata, Nby., near J. Munsteriana of the Richmond basin. ANIMALS. The marine species of Invertebrates include Brachiopods of the genera Rhynchonella, Spiriferina, and Terebratula ; Lamellibranch Mollusks of the genera Pecten, Lima, Avicula, Monotis, Jlalobia, Daonella, Posidonomya, Corbula, Myophoria, and others ; and Cephalopods of the old genus Orthoceras, and under the Ammonite group, of the genera Sageceras (Figs. 1190, a), Trachyceras (Figs. 1191, a), Arcestes, Tropites, which are characteristic, and also many others. A few Insects have been described by Scudder from Fairplay, Col., which are supposed to be Triassic. All but one, a Hemipter, are of the MESOZOIC TIME TKIASSIC AND JURASSIC. 757 Cockroach group (Blattariae) ; and out of the 17 species, 11 have the wings like those of the Paleozoic species as to transparency and nervures, and belong partly to described genera, while six are Mesozoic in the character of 1190. 1191 a. AMMONITE FAMILY. Fig. 1190, Sageceras Haidingeri; 1190 a, same in profile; 1191, Trachyceras Whitney! ; 1191 a, same, showing form of pockets. Gabb. the nervures, and in having the fore wings more or less opaque, approach- ing thus the modern kinds. This commingling of Paleozoic and Mesozoic types leads Scudder to the conclusion that the beds are Triassic, although referred by Lesquereux, on the ground of some imperfectly preserved fossil leaves, to the Permian. The Trias of Idaho, which Hyatt considers the lowest yet found in this country, contains, according to White (1879), Terebratula augusta, T. semisimplex, Aviculopecten Idahoensis Meek, A. Pealsi, A. altus, Eumicrotis curta Mk. & H., Arcestes cirratus (?), Meekoceras aplanatum, and others. In western Nevada, West Humboldt region (King), Orthoceras Blakei, Sageceras Haidingeri, Trachyceras Whitneyi, Arcestes Nevadensis Mk., A. Gabbi, Myophoria alta, Monotis subcircularis, Halobia dubia, Aoicula Homfrayi, Halobia (Daonella} Lommeli, Pecten deformis, Pentacrinus asteriscus (?), etc. Hyatt reports from Desatoya Moun- tains, New Pass, and Walker's Lake of Nevada, besides some of the above forms, Gym- notoceras rotelliforine, Trachyceras Whitneyi. In the Taylorville region, Plumas County, Cal., occur, as identified by Hyatt (1829) from the successive beds : (a, or lowest) slates, the Monotis bed, Monotis subcircularis Gabb (which he says may be M. salinaria Schloth.), Pecten deformis Gabb, and at the top, Daonella tenuistriata Hyatt ; (&) a limestone, the Rhabdoceras bed, with, besides the preceding, species of Nucula, Lima, Modiola, Myacites, Bhynchonella, and Ammonites of the genera Ammonites and Arcestes, Ehabdoceras Eusselli (a strait Ceratite), with Belem- nites of the genus Atractites ; (c) the Halobia bed, with species of Halobia, Arcestes, Tropites ; (c?) the Hosselkus limestone, with the same Ammonites, and others of the genera Ceratites, Badiotites, and Juvavites. The upper subdivision is referred by Hyatt to the Lower Carnic of the Alpine (Upper) Trias, and the others to the Upper Noric. From British Columbia have been reported by Whiteaves, who has described several of the species as new from Queen Charlotte Islands, the Ammonites Arcestes Gabbi, 758 HISTORICAL GEOLOGY. Badiotites Carlottensis, Aulacoceras Carlottensis ; from northern Vancouver, Arcestes Gabbi and Arniotites (Balatonites} Vancouverensis ; from Liard Kiver, about 59 16' N. and 125 35' W., Spirifer borealis, Terebratula Liardensis, Halobia (Daonella) Lommeli, H. occidentalis, Monotis subcircularis Gabb (probably = Pseudomonotis Ochotica of Keyser- ling), Nautilus Liardensis (near N. Sibyllce of Spitzbergen), and Trachyceras Canadense (1889). All are of the Upper Trias. Of Fishes, few species are known. Several Saurian vertebrae are mentioned by King as having been observed in the Trias of western Nevada, and Hyatt speaks of fragments of Vertebrates in the Sierra Nevada Triassic. A large Crocodilian of the genus JSelodon has been described by Cope, from the Gallinas valley in the Sierra Madre Mountains, New Mexico, under the name Typothorax coccinarum. Dystrophasus vicemalce Cope (1877), found by Newberry in Painted Cafion, southeastern Utah, is supposed to be a Dinosaur. Although Amphibians are many and of great size in Europe at this era, no remains are yet known from the western half of North America. Jurassic Formation. The Jurassic beds are much less barren in fossils than the Triassic, and yet are seldom prolific in species. Gastropods are rare, and Cephalopods not numerous. Invertebrate species were first discovered in them by Meek, at the Black Hills, where the species here figured occur along with many others. The Crinoid disk, Fig. 1192, is of the genus Pentacrinus. A species 1193. 1192-1197. 1194. 1196 a. 1196. Fig. 1192, a segment of the column of Pentacrinus asteriscus ; 1193, Monotis curta ; 1194, Trigenia Conradi ; 1195, Tancredia Warreniana ; 1196, Quenstedioceras cordiforme ; 1196 a, side view of same, a little reduced ; 1197, Belemnites densus. Meek. of the Ammonite group is represented in Figs. 1196, 1196 a. The Belemnite, Belemnites densus Meek, Fig. 1197, is from these beds, which have been named by Marsh the Baptanodon beds. (These Baptanodon beds, near Como, Colorado, are marine, and overlie Red beds which are referred to the Triassic; above them are the freshwater Atlantosaurus beds of Marsh, and overlying these comes the Dakota group.) The fossil here represented is the lower end of the internal bone answering to the bone of the Squid, but differing from those of modern species in the texture and weight of the MESOZOIC TIME TRIASSIC AND JURASSIC. 759 posterior portion or " guard." (A perfect bone of similar nature is shown in Fig. 1300, page 782.) The Jurassic of Taylorville, Plumas County, Cal., has afforded Hyatt many species, and among them, from the Upper Lias, Pinna expansa. Fig. 1201 ; from the Oolyte, Lima Taylorensis, 1199, and Entolium gibbosum, 1200 ; and from thfe Coral bed, Stylina tubulifera, 1202. The Ammonite, Arnioceras Nevaduum (Fig. 1198) is from the Jurassic at Volcano, Nev. (Am. Jour. Conch., vol. v., pi. 3). 1198-1202. 1198. Fig. 1198, Arnioceras Xevaduum ; 1199, Lima Taylorensis; 1200, Entolium gibbosum ; 1201, Pinna expansa; 1202, Stylina tubulifera. Original. Shells of the species of Aucella from the Auriferous slates are repre- sented in Figs. 1203-1205. Aucella Erringtoni (so named in commemoration of the first discoverer of fossils on the Mariposa estate, Miss Errington) occurs in the partially metamorphic upturned slates ; Fig. 1203 represents the common form ; and 1204, a narrower variety occurring in the sandstone. The Trias sic genus Monotis is continued, one species of which is shown in 1203 1208-1205. 1204 1205 MOLLTTSK. Aucella Erringtoni. Meek. Fig. 1193. Trigonia, related to Myophoria, has its first American species. Other characteristic genera of Lamellibranchs are Tancredia, Lima, Gervillia, Gryphceaj Inoceramus, and Pholadomya. 760 HISTORICAL GEOLOGY. The Jurassic of Dakota, Wyoming, and Utah have afforded Ostrea stringilecula, Tancredia extensa, Camptonectes bellistriatus, and the Ammonite Quenstedioceras cordi- forme. That of Idaho afforded White : Pentacrinus asteriscus, Ostrea stringilecula, species of Tancredia, Trigonia, Myacites, etc. In the Uintah Mountains, where the rocks are shales and sandstones with limestone, occur Pentacrinus asteriscus, Belem- nites densus, Trigonia, Gryphcea calceola, Myophoria lineata, Camptonectes bellistriatus, Eumicrotis curta, etc. ; and in the Wasatch have been found Cucullcea Haguei, Myophoria lineata, Myacites subcompressa, Volsella scalpra (King's Report on the 40th Parallel). In the West Humboldt region, west Nevada, occur Belemnites Nevadensis, species of Montlivaltia, etc.; and probably from this region came the Ammonite, Arnioceras JIumboldti; in Esmeralda County, Nev., Vermiceras Crossmani, Arnioceras Nevadense; in Inyo County, Cal., Arnioceras Woodhulli. Jurassic beds at Taylorville, Cal., on the Sierra Nevada, afforded Hyatt, in the lower toeds referred to the Lias, besides the most of the above genera, species of Pinna, Entolium, Goniomya, Pleuromya; also an Echinoderm of the genus Cidaris and a Crustacean of the genus Glyphcea. The Middle Oolytic beds contain, among the species, Ammonites of the genera Grammoceras and Sphceroceras ; and the Upper Oolyte, species of the genus Rhacophyllites, with 3 species of Trigonia in the lower bed referred to the Callovian division of the Oolyte, and several species of Coral of the genus Stylina referred to the Corallian, besides the Camptonectes bellistriatus Mk.,and the Rhacophyllites of the Upper Oolyte. Hyatt speaks of the contrast of the species with those of the summit region of the Black Hills, southeastern Wyoming, whose Ammonites are of the Cardioceras family and whose beds are Callovian or Oxfordian. The Mariposa beds extending to near Coif ax, Placer County, Cal., contain, according to Hyatt, Cardioceras dubium of Oxfordian age, and striated Aucellce (Figs. 1203-1205) in great numbers, Perisphinctes of the same types as those found in the Upper Jura, Upper Oxfordian, and Volgian of Russia, namely, Perisphinctes virgulatiformis, P. Colfaxi, P. Muhlbachi, and Belemnites Pacificus. None of these species pass into the Knoxville beds. The Queen Charlotte beds have afforded Whiteaves (Mesozoic Foss., Can. Survey, 1884) species of the Ammonite group of the genera Lytoceras, Haploceras, Ancyloceras {A. Eemondi of Gabb), Hamites, and also species of Trigonia, Inoceramus, Aucella, Amusium, Yoldia, etc.; also Belemnites densus. Among the Arctic fossils of this period, there are, at Prince Patrick Island, Ammo- nites M'Clintocki, a species near A. concavus Sow., of the Lower Oolyte; and at Cook's Inlet, Ammonites Wosnessenski, A. biplex Sow. (?), Belemnites paxillosus (B. niger List ?), and Pleuromya unioides Br. (TJnio liassinus Schubler). A. biplex also is reported to occur in the Chilean Andes, in latitude 34 S., as well as in Britain and Europe. 1. Fishes. Fishes are rare fossils. The teeth of Ceratodus Gilntheri of Marsh have been described from the Upper Jurassic (Atlantosaurus beds) of Colorado. 2. Reptiles. The Upper Jurassic formation of Colorado and Wyoming has afforded remains of a few Amphibians, many great and small Beptiles, and of some Mammals. The specimens are thus far from the " Baptanodon and Atlantosaurus beds " of Colorado and Wyoming. They include Sea-Saurians related to the Ichthyosaurs (page 784), and also Dinosaurs, Crocodilians, Turtles, and Pterosaurs or Flying Keptiles. Enaliosaurians (Ichthyopterygians). These Sea-Saurians are the most fish-like of Eeptiles. This appears (1) in their biconcave vertebrae (Fig. MESOZOIC TIME TRIASSIC AND JURASSIC. 761 000% O0o o Fig. 1206, Baptanodon discus, left hind paddle (x ); /, femur ; t and m, bones answering to tibia and fibula; I, first digit; V, fifth digit. Marsh. 1315 a, page 784); (2) in their locomotive organs or paddles (Fig. 1206) which are fin-like in having no defined limb-bones beyond the upper, the rest of the limb being represented 12Q6 by several series of bones, and the number of series exceeding the normal number of fin- gers, five ; and (3) in the absence of a breast bone, and the presence of dorsal fins. The specimens from Wyo- ming of Baptanodon discus of Marsh indi- cate a species eight or nine feet in length, with a toothless head and the orbit of great size (as in Ichthyosaurs, page 784), with a sclerotic ring of 8 plates, which is conical as in some birds. Dinosaurs. Localities in Colorado and Wyoming are the most important source of what is known about Jurassic Dinosaurs. They were the most gigantic of terrestrial animals, in some cases reaching a length of 70 or 80 feet, while at the same time they had a height of body and massiveness of limb that, without evidence from the bones, would have been thought too great for muscle to move. Besides this, some of the huge beasts had the most diminutive of brains; but, as a compensation, a nervous mass in the sacrum 20 to 30 times as large as the brain for use in connection with the hinder limbs and tail. There were both Carnivorous and Herbivorous kinds, the latter the inferior. The American Herbivorous species are of three groups : (a) The Sauropods or Saurian-footed ; kinds having the fore and hind limbs nearly equal, crocodile-like, with all the feet five-toed (that is, with five usable toes); the limb bones solid, but the vertebrae, especially the anterior, cavernous, and thereby light, (b) The Stegosaurians, having very short fore limbs ; the fore feet five-toed and hinder three-toed ; the limb bones and vertebrae solid; and the body covered with bony pieces or plates; the vertebrae all biconcave, (c) The Ornithopoda or bird-footed, having very short fore limbs with the long hind limbs three-toed, bird-like, rarely four- toed ; the bones of the hind limbs hollow, but the vertebrae solid. (Marsh.) The Carnivorous species have in all cases the fore limbs short compared with the hind limbs, and the latter usually three-toed, bird-like. The limb bones are hollow, and the vertebrae are more or less cavernous, in order, as in birds, to have less to lift, especially in the anterior part of the body. The following are some examples of Jurassic species under the several subdivisions. The specimens are all from the Atlantosaurus beds of Colorado and Wyoming. 762 HISTORICAL GEOLOGY. (1) Herbivorous Dinosaurs. (a) Sauropods. An idea of the skull in this group is afforded by the following figures of Diplodocus longus Marsh, found near Canon City. The length of skull in this species was about 21 inches; of 1207. 1208. I e Fig. 1207, Diplodocus longus, skull, side view (x ); 1208, id. upper view (x J); o, aperture in maxillary ; &, antorbi- tal opening; c, nasal opening; c', cerebral hemispheres; d, orbit; e, lower temporal fossa; /, frontal bone ; /*, fontanelle ; TO, maxillary bone; m', medulla; n, nasal bone; oc, occipital condyle ; oZ, olfactory lobes ; op, optic lobe ; p, parietal bone ; pf, pre-frontal bone ; pm, pre-maxillary bone ; q, quadrate bone ; qj, quadrato-jugal bone. Marsh. brain, about three inches ; of body, 50 feet. The position and relative size of the brain is shown in Fig. 1208 at c'. The teeth were peculiar, being very slender and long, and confined to the terminal part of the jaws. The animal is supposed to have been a hippopotamus-like wader, and to have lived on vegetation in the waters. MESOZOIC TIME TBIASSIC AND JUKASSIC. 763 1209-1211. 1210. 1209. The general character of the limbs, their height and massiveness, and the form of the pelvic bones, are exhibited in Figs. 1209-1211 of Morosaurus grandis Marsh, a species about 40 feet long. The femur (/) is about four feet in length. The teeth (Fig. 1211, half the ^ J ^ 1211. natural size) are shorter than in the preceding species, and more numer- ous. Nearly complete skeletons of this Moro- saurus have been ob- tained by Marsh in Wyoming. Fig. 1212 represents a restoration of an allied species, the Brontosaurus excelsus Marsh, of which also a skeleton nearly complete has been obtained. The DINOSATTK. Morosaurus grandis (x^). Fig. 1209, fore leg ; s, scapula ; total length is about 60 feet, and the height of the skeleton at the middle of the body about 15 feet, showing great magnitude ; and yet it had, relatively to size of body, one of the smallest of heads known among vertebrates. Like Morosaurus, c, coracoid ; h, humerus ; r, radius ; u, ulna ; uc, ulnar carpal ; I, first metacarpal; Vmc, fifth metacarpal. Fig. 1210, hind leg; il, illiac ; is, ischium ; p, pubis ; /, femur ; t, tibia ; /', fibula ; a, astragalus; c, calcaneum ; Vmtf, fifth metatarsal. Fig. 1211, tooth (xj). From Marsh. 1212. Fig. 1212, Brontosaurus excelsus, restoration (x x&y). Marsh. its vertebrae were very light and cavernous, with thin walls, even in the axis ( of the sacrum. The feet were large enough to make tracks a square yard in area. The sixth cervical vertebra was over 25 inches high and 21 broad. The size of neck was still greater in another species, Apatosaurus laticollis 764 HISTORICAL GEOLOGY. 1213. Marsh, the corresponding dimensions of a cervical vertebra (Fig. 1213) being 4 feet and 2^ feet. In Atlantosaurus immanis Marsh, a species probably 70 or 80 feet long, the femur was over six feet in length. (b) Stegosaurians. The Stegosaurs of Marsh were other huge species, but with the fore limbs much the shorter, and all the bones solid. They were remarkable for the crest of great bony plates along the back, the diminutive size of the brain, and the enormous supplementary nervous mass in the sacrum. The figure is the restora- tion of Stegosaurus ungulatus Marsh, by the describer, -fa the natural size. The head had a horny beak. The throat was covered with small ossicles. The larger of the plates along the back were 1^ feet broad ; and the spines along the caudal portion, nearly 2 feet long. All the plates and spines had originally a thick horny cover- ing. The relative size of the brain and the nervous mass in the sacrum is shown in the figures, of J natural size : Fig. 1215, the brain ; 1216, the mass in the sacrum. 1214. 1214 a. Fig. 1218, Apatosaurus . laticollis, cervical vertebra (x &) c, concave posterior articular surface ; d, diapophysis ; p, para- popysis ; h, hatchet bone, or anchylosed rib ; z', postzygapophysis. Marsh. Fig. 1214, restoration of Stegosaurus ungulatus (x ^5) ; 1214 a, tooth of same (x 2). Marsh. (c) Ornithopoda. The animals of this group of Herbivorous Dinosaurs were bird-like in feet, and strikingly so in the pelvic bones. Both of these characters are shown in the restoration of Camptosaurus dispar of Marsh MESOZOIC TIME TRIASSIC AND JURASSIC. 765 (Fig. 1217), in which the skeleton is reduced to pare with Fig. 1423, page 850.) Fig. 1219 represents the hind leg of an allied species, Laosaurus con- sors of Marsh, and 1219 a, a tooth. Nanosaurus agilis Marsh (Fig. 1220), from Colorado, is the smallest of known Dinosaurs, being about as large as a partridge. Another spe- cies, Nanosaurus Hex Marsh, also from Colorado, was not larger than a Fox. (2) Carnivorous Dinosaurs. Fig. 1221 represents a restoration of Cera- tosaurus nasicornis Marsh, a mod- erately large species related in general characters to the Megalosau- rus of Europe. The name nasicornis alludes to their having a horncore (h in Fig. 1222) on the nose. Owing to the form of the pelvis, the body was keeled beneath ; and the exist- ence of such a keel in some Triassic species is supposed to account for an impression sometimes found in the sandstone between pairs of footprints. the natural size. (Com- 1215-1216. 1216. CTt- Fig. 1215, cast of brain of Stegosaurus (x |); ol, olfac- tory nerves ; op, optic lobes ; on, optic nerve ; c6, cerebellum ; ra, medulla oblongata. Fig. 1216, cast of cavity of nervous mass in the sacrum, seen from above (x \) f,f',f", each foramen between two sacral vertebrae. Marsh. 1217 1217-1220. 1219 HERBIVOROUS DINOSAURS. Fig. 1217, restoration of Camptosaurus dispar (x ^,) ; 1218, tooth of C. medius; 1219, Laosaurus censors, hind leg (x T y) ; 1219 a, tooth of same; 1220, Nanosaurus agilis, dentary bone, as seen from the left, natural size. All from Marsh. 766 HISTORICAL GEOLOGY. 1221. 1222. DINOSAUR. Fig. 1221, Restoration of Ceratosaurus nasicornis (x ,fo) ; 1222, skull of same (x ft) ; h, horncore. Marsh. Allosaurus Marsh is another genus of Carnivorous Dinosaurs from the Atlantosaurus beds, near Megalosaurus in its characters. Labrosaurus of Marsh is another. 1223. 1224. TURTLES. Fig. 1223, Glyptops, a Turtle skull, natural size; 1224, carapace of probably the same species (x |). Marsh. MESOZOIC TIME TRIASSIC AND JURASSIC. 767 Testudinates. Glyptops ornatus Marsh (1890) was a Turtle with an -elaborately sculptured skull, from the freshwater Atlantosaurus beds of Wyoming. The form of the skull is shown in Fig. 1223. The carapace represented in Fig. 1224 was found in the same beds, and is probably of the same, or an allied, species. A tortoise over a foot in diameter has been described by Cope (1878), under the name Compsemys plicatulus, from the Upper Jurassic beds of Coino, Wyoming. The bony case or carapace is as complete, according to Cope, as in a modern tortoise, being without any embryonic or transitional characters. Pterosaurs, or flying Reptiles (Figs. 1321 to 1325, pages 786, 787), are known from a few bones from Wyoming. The character of the wing in the Ptero- saurs is shown in Fig. 1321. The type specimen of Pterodactylus montanus Marsh is the distal portion of the metacarpal bone. The size indicates a spread of wing of four or five feet. 3. Birds. A portion of a skull of a bird rather larger than a Blue Heron (Ardea herodias), from the Atlantosaurus beds of Wyoming, is the 12-25 1226 1225-1249. 1230 MAMMALS. Fig. 1225, Allodon laticeps, upper jaw, view from below; 1226, A. fortis, right premaxillary, outer view ; 1227, id., inner view ; 1228, id., lower incisor ; 1229, id., left upper jaw ; 1230, Otenacodon serratus, right lower jaw ; 1231, id., left lower jaw ; 1232, C. potens, left lower jaw ; 1233, front view, showing the two long incisors together ; 1234, id., right upper jaw ; 1235, Stylacodon gracilis, left lower jaw ; 1236, Dryolestea priscus, left lower jaw ; 1237, D. vorax, left lower jaw ; 1238, Laodon venustus, left, inner view ; 1239, Asthe- nodon segnis, right, outer view ; 1240, id., anterior part left lower jaw ; 1241, Tinodon bellus, right, inner view ; 1242, Diplocynodon victor, outer view ; 1243, Docodon striatus, inner ; 1244, Menacodon rarus, outer view ; 1245, id., inner ; 1246, Enneodon crassus, outer view ; 1247, Priacodon ferox, inner view ; 1248, 1249, Paurodon valens, left lower jaw. All natural size except 1225, 1230, 1238, which are | ; and 1242, 1243, f. From Marsh. 768 HISTORICAL GEOLOGY. basis of the species Laopteryx prisons of Marsh. It probably had teeth and biconcave vertebrae. 4. Mammals. Remains of Jurassic Mammals have been described by Marsh from the Atlantosaurus series, and mostly from Wyoming, where portions of lower jaws of some hundreds of individuals have been found in thin dirt-beds. (The same beds have afforded, besides Dinosauriau bones, remains of Crocodiles, Turtles, small Lizards, and Fishes, besides the Laop- teryx.) The Mammals were like mice and rats in size, the length of the lower jaw varying from half an inch to one and one half inches. Specimens, more or less perfect, of the jaws of species are shown in Figs. 1225-1249, from Marsh. Ctenacodon has a large cutting incisor, as Figs. 1230-1233 show, and is referred, along with the genus Allodon, to the same family with the genus Plagiaulax of Owen. The characters of the others are mostly those of Marsupial Insectivores. The number of teeth in some modern Marsupials is 2 to 4 above the normal number 44 ; but in the Triassic and Jurassic species, where determinable, as tabulated by Osborn, it is beyond the normal number by 4 to 24 teeth ; the earliest Dromatherium is stated to have had 56 teeth ; the Jurassic Stylacodon, 68. FOREIGN TRIASSIC AND JURASSIC. 1. TRIASSIC. At the commencement of the Triassic period, Scotland and western England were mostly dry land. Triassic beds show that the only under- water or rock-making region of western England (Wales included) was that of a broad channel, passing westward over Cheshire to the coast of the Irish Sea by Liverpool, and northward of that city. Eastward, the chan- nel opened into the North Sea of the era, or into its great sea-border flats ;. and the shore line stretched northward nearly to Newcastle, thence along by eastern Scotland, and southwestward to Torquay on the British Channel. But the seashore flats appear to have been emerged land over southeastern England, the Triassic being absent according to evidence from borings. In Europe, southeast of England, beyond a broad border region of the continent (now under Tertiary or Cretaceous rocks), Triassic beds again appear over both eastern France and the Netherlands ; and the two areas, united (beneath a strip of Tertiary) behind the Carboniferous area of the Belgian border, continue from the Vosges Mountains to Saxony, Bohemia, and the Juras on the borders of Switzerland, and also along the western and eastern Alps into Italy and Austria. Further, they appear again over a large surface in Russia, west of the Urals, reaching from the Caspian to the coast east of the White Sea, and again farther north, in Spitzbergen, as already stated. And since the interval between the Triassic outcrops of Austria and Eussia, and that between the Alpine and the Franco-Prussian areas are largely under later rocks, it is probable that at this period nearly all outside of Scandinavia and the Baltic provinces in Russia was a shallow MESOZOIC TIME TEIASSIC AND JURASSIC. 769 continental sea. In the earlier and later part of the Triassic, it was very shallow, the conditions those of sea margins and seashore basins, and brack- ish-water flats ; in its middle portion of somewhat deeper waters ; but about the region of the eastern Alps, and along the side of the Alps toward the Mediterranean, as well as in southern France and Austria, the waters, judg- ing from the prevalence of limestones, their thickness and the fossils, were those of a clear, open sea. This region has been designated the Mediterra- nean region. ROCKS SUBDIVISIONS, KINDS AND DISTRIBUTION. 1. LOWER TRIAS or VOSGIAN. Represented generally by red or variegated sandstones passing to whitish marlytes and pebbly beds; salt beds are sometimes present, and also gypsum. In England it includes the Lower Red Sandstone of the Trias, 1000 feet to 2000 feet thick ; in Germany, the Bimtersandstein ; in France, the Gres des Vosges and Gres bigarre (bunter and bigarre meaning variegated)-, but in the eastern Alps, in Lombardy, and the Tyrol, a limestone, the Gutenstein, underlying the Werfen sandstone with rock salt and gypsum. 2. MIDDLE TRIAS or FRANCONIAN. The rock is limestone in Germany, France, and the Alps ; it is not recognized in England. It is represented by the Muschelkalk of Germany, with the Wellenkalk below, and affords rock salt in Wurtemberg ; and by the Calcaire Conchy lien in France. 3. UPPER TRIAS. (1) Keuperian. In England mostly like the Lower Trias in its rocks ; it affords rock salt at Cheshire. In Germany there are, below, red shales and marlytes with thin coal seams the Kohlen- keuper or Lettenkohle ; and above, the Keupermergel, marlytes containing gypsum. Gypsiferous beds and rock salt occur in Lorraine, and at Salz- kammergut, near Salzburg, Austria. In the eastern Alps, there are the St. Cassian beds ; in Sweden, gray and red marlytes, with some good coal. (2) The Rhcetic, so-named from the Rhaetic Alps. The beds are limestone or shales. They include the Kossen beds of Germany, the Avicula contorta beds ; the larger part of the Dachstein limestone of the eastern Alps ; and in England the Penarth beds of shales overlying the Trias from Yorkshire to Lyme-Regis, 50 to 150 feet thick. One to three bone-beds occur in the lower part in England, and also in Bourgogne, Hanover, Brunswick, and Franconia. The Rhaetic is sometimes placed at the base of the Lias. The Trias has great thickness in the Alps, especially the Italian, it being nearly 13,000 feet along a belt from Bardonneche (Savoy), by the Mont Cenis tunnel, to Modena. This great thickness is owing to the fact that preparations were in progress, through a geosyndine of accumulation, for the Tertiary mountain making, which took place along the range at the close of the Miocene. In peninsular India, the upper part of the Gondwana series, the Panchet group, is Triassic; it is without marine fossils. Outside of the peninsula, Triassic beds occur in DANA'S MANUAL 49 770 HISTORICAL GEOLOGY. the Salt Range of the Punjab ; in northern Kashmir, and along the mountain region as far as Spiti in western Tibet, resting on Carboniferous rocks, where the succession of beds from the Lower to the Upper is closely like that of the Alps. They are concealed by Cretaceous if they exist in Sind. In South Africa, the Karoo beds include, above the Ecca beds (which are referred to the Permian, and are equivalents of the Lower Gondwana of India) : (1) the Kimberley shale ; (2) the Beaufort beds ; and (3) the Stormberg beds or Upper Karoo ; and the last have afforded Palceoniscus Bainei, P. sculptus, Ceratodus Capensis, etc. None of the fossils are marine. In Australia, in New South Wales, the widespread Hawkesbury sandstone, mostly unfossiliferous, is probably Jurassic or Jura-Trias. In New Zealand, Dr. Hector has described as Triassic an Qreti series, including great bowlder deposits, in northern and southern New Zealand, containing stones up to 5' in diameter ; and the overlying Wairoa series, in which are some Upper Triassic fossils. For further details as to subdivisions, see page 773. LIFE OF THE FOREIGN TRIASSIC. PLANTS. The range of Triassic plants corresponds with, that of North America. Among Conifers occur the Cypress, Figs. 1250, 1251, Voltzia hetero- phylla, from the Lower Trias, and Spruces of the genus Albertia. Of Cycads, 1250-1252. 1252 Fig. 1250, Voltzia heterophylla ; 1251, one of its fruit-bearing branches ; 1252, Pterophyllum Jsegeri. Figs. 1250, 1251, from Vogt ; 1252, Bronn. Pterophyllum Jcegeri, Fig. 1252, is a species from the Upper Trias. Ferns and Equiseta were common. ANIMALS. 1. Radiates, though not abundant, are represented by Cri- noids, Starfishes, and a few Corals. Among Crinoids, the Middle Trias (Muschelkalk) affords abundantly the Lily Encrinite, Encrinus liliiformis, Fig. 1253. The Lamellibranch, Gervillia socialis, Fig. 1254, is from the same limestone ; the Myophoria, Fig. 1255, of the Trigonia family, is from the Upper Trias. The Avicula contorta Portl., characteristic of the Ehaetic beds, is represented in Fig. 1256. The Cephalopods were represented by Ceratites, one of which, from the Muschelkalk, C. nodosus Schloth., is shown in Figs. MESOZOIC TIME TRIASSIC AND JURASSIC. 771 1253. 1253-1257. 1258, 1259 ; an Ammonite, from the Keuper, is the Cladiscites tornatus Braun. The genus Choristoceras, of the Ammonite family, contains Triassic species that are like Ceratites 1254. in the partitions, but the whorls of the shell are not con- tiguous, a feature here first presented under the type ; and Cochloceras of the Trias has a turreted shell like Turrilites of the Cretaceous. 2. Crustaceans, Insects. Ostra- coids are common. Estheria minuta Goldf. (Fig. 1257) abounds in a stra- tum of the Lower Trias, and has given rise to the name Es- theria shales. Macrurans, allied to the Crawfish or Lobsters, occur, one of which is Pemphix Sueurii Desm., of the Muschelkalk (Fig. 1262). CBINOID. Fig. 1253, Encrinus liliiformis. LAMELLIBRANCHS. Fig. 1254, Gervillia socialis ; 1255, Myophoria lineata ; 1256, Avicula contorta. OSTRA- COID. Fig. 1257, Estheria minuta. Figs. 1253, 1257, D'Orbigny ; 1254, Vogt ; 1255, Lyell ; 1256, Portlock. 1258-1261. 1260. 1262. CEPHALOPODS. Fig. 1258, Ceratites nodosus ; 1259, dorsal view of portion of same, showing the dorsal lobes o/ the septa ; 1260, Cladiscites, tornatus ; 1261, side view of same (x). Figs. 1258, 1259, D'Orbigny ; 1260, 1261, from Vogt. Pemphix Sueurii, from Naumann. Insects of the Trias are Cockroaches (Orthopters) of both palseic and modern type ; several true Neuropters ; and Beetles or Coleopters of the Curculio (Weevil) family, as Curculionites prodromus Heer, and of Chrysomelids and Buprestids, from the Lower Keuper. 772 HISTORICAL GEOLOGY. 3. Fishes. Hybodont and Cestraciont sharks of the genera Hybodus, Acrodus, and Strophodus here first appear : Fig. 361, a tooth of Hybodus minor Ag., from the Keuper, and Fig. 362, of H. plicatilis Ag. There were also Ganoids of the genera Saurichtliys, Gyrolepis, Amblypterus, Palceoniscus, Pycnodus, etc. ; and Ceratodus of the Dipnoans. 4. Amphibians. The Labyrinth odont, Mastodons aur us giganteus, was a scale-covered species ; Fig. 1263 represents its cranium, which was two feet long, and Fig. 1263 a, a tooth three inches long. Several other species of Labyrinthodonts are known from British and European beds. The tracks, Fig. 1264, named Chirotherium (from x^p> hand, and Orjpiov), are supposed to be those of a Labyrinthodont. 1263 a. 1263. 1263-1265. 1265. 1264. AMPHIBIANS. Fig. 1263, Mastodonsaurus giganteus (x &) ; 1263 a, tooth of same ; 1264, Chirotherium (,x T \,) ; 1265, track of a Turtle ? Figs. 1263, 1263 a, Braun ; 1264, 1265, D'Orbigny. 5. Reptiles. The British and other foreign Triassic Keptiles comprise species of Ehynchocephs, Anomodonts, Belodont Crocodilians, Dinosaurs, 1266. RHYNCHOCEPH. Fig. 1266, Telerpeton Elgiiiense. From .Maiiteli. Chelonians, and Sea-Saurians. Under the Khynchocephs, there are the genera: Hyperodapedon of Huxley, species of which occur in the Triassic MESOZOIC TIME TRIASSIC AND JURASSIC. 773 beds of India, as well as Great Britain ; and Rhynchosaurus, from the Upper Trias of England, both having the jaws beaked at the extremity, but supplied with short palatal teeth. Telerpeton Elginense (Fig. 1266), from the Elgin sandstones of Scotland (at first supposed to be Devonian in age), is referred to the Khynchocephs. The Anomodonts include Dicynodon of Owen, and other genera from the Karoo beds of South Africa, and from India; also horned Reptiles from Elgin, one of which, the Elginia mirabilis, had, besides a pair of long horns in the position of those in cattle, other smaller horn-like projections over the front and sides of the cranium. The Elgin fauna was closely like that of the African Karoo beds, and the Indian Panchet and Maleri beds. Crocodilians of the genus Stagonolepis occur in the Upper Trias of Eng- land and Scotland, and a Belodont in the Rhsetic beds of Germany. The carnivorous Dinosaurians included Thecodontosaurus and Palceosaurus of the Keuper. The earliest Sea-Saurians are from the Middle Trias, and are of Plesio- saurian type. The paddles have the limb bone distinct and the normal number of fingers ; the teeth are in sockets ; the vertebrae feebly biconcave ; the neck very long ; the orbits very large, without a sclerotic ring. The Triassic genera Simosaurus, Nothosaurus, and others, 1267. are characterized by very large orbital openings. Both of the genera Plesiosaurus and Ichthyosaurus have Rhsetic species. Turtles are represented in the Keuper by the Proganochetys Quenstedtii of Baur. The tracks, Fig. 1265, are supposed to be those of a Turtle, as the rights and lefts, in the series observed, 1267 a. are far apart. 6. Mammals. The earliest remains of Mammals are found in the Rhsetic beds ; one species at Wurtemberg (Figs. 1267, 1267 a), Microlestes antiquus Plieninger, and another, M. Moorei Owen, from Somerset, England. The teeth resemble those of Dromatherium. The species were Marsupial. Tritylodon is a related genus from the Triassic of South Africa. Characteristic Species. 1. Vosgian, or Lower Trias (in the Alps, the Werfenian). In Germany, the upper part contains, with sandstone, some limestone or dolomyte and gypsum, with Myophoria costata, M. vulgaris, Naticella costata, Estheria minuta, Voltzia heterophylla, Equisetum arenaceum, Chirotherium (tracks), Placodus, Nothosaurus, Trematosaurus. Other Lower Triassic species are Ceratites Middendorfi, Triolites Cassianus, Kenodiscus Schmidti, and Dinarites Liccanus. In the Alps and Mediterranean province : the Werfen shales ; stage of Tirolanus Cassianus and Naticella costata. 2. Franconian, or Middle Trias. In Germany: (a) The Wellen Kalk in Franconia (Wurzburg, etc.) and elsewhere, with Beneckia Buchii (Nautilus bidorsatus), Spirifer fragilis, Gervillia costata, Gr. socialis, Myophoria orbicularis ; (&) limestones, partly 774 HISTORICAL GEOLOGY. oolytic, with Ceratites nodosus, Encrinus liliiformis, Myophoria vulgaris, Monotis Alberti, Lima striata, Pecten discites, Spirifer fragilis. In the Alps, the Virgloria or Gutenstein limestone (the Virgloriari) : (a) stage of Trachyceras balatonicum and T. binodosum; (6) stage of Trachyceras trinodosum. In Lombardy the same stages : Varenna marble, Salvator dolomyte, Besano dolomyte. Other Middle Triassic species are Ptychites gibbosus, Gymnites incultus, Foosdiceras bidorsatum, Atractites secundus. 3. Upper Trias. (1) Keuperian. In Germany: (a) Lettenkohle group with the Grenzdolomit ; Anoplophora lettica, Myophoria Goldfussi, Estheria minuta, Ceratodus, JEquiseta, Calamites, Voltzia ; (6) Keupermergel, with Anoplophora Munsteri, Estheria, Mastodonsaurus Jcegeri, Equiseta, Pterophyllum Jcegeri, Calamites arenaceus, Danceopsis. In the Alps : (a) Wengen shales overlaid by (6) the St. Cassian beds and (c) the Hallstadt limestone of the Salzburg region ; (d) Wetterstein limestone and (e) Schlern dolomyte ; with the stages (a) Arcestes giganto-galeatus and Pinacoceras Metternichi (overlying beds of the Middle Trias containing Choristoceras Haueri) ; (6) Pinacoceras parma, and Didymites globus ; (c) Arcestes ruber ; (dT) Didymites tectus ; (e) Tropites subbullatus. In Lombardy : the zones of (a) Trachyceras Eeitzi and T. Curionii; (&) T. Archelaus and Daonella Lommeli. (2) Mhcetic beds. In England : Avicula contorta, Pecten Valoniensis (these two species characteristic and abundant), Pleurophorus elongatus, Pullastra arenicola, Monotis decussata, Modiola minima, Ostrea liassica; Spirifer Munsteri, Estheria minuta; Acrodus minimus, Hybodus plicatilis, Saurichthys apicalis, Gyrolepis tenuistriata, vertebrse of Ichthyosaurs and Plesiosaurs, tracks of Chirotherium ; Microlestes in Bone-bed. Many of the species occur also in the Lias. In the Alps : (a) Haibl shales ; (6) Hauptdolomit (Dachstein limestone); (c) Kossen beds : stages (a) Trachyceras aonoides, Cardites crenatus, Germllia bipartita ; (6) Turbo solitarius, Avicula exilis, Megalodon triqueter; (c) Avicula contorta. The " White Lias " of England, at the top of the Khaetic, also called the Infra-Lias, is the Hettangian of Renevier. The Triassic rocks of Spitzbergen, partly bituminous shales, have afforded species of Nautilus, Ammonites, Ceratites, Halobia, etc., closely like, if not identical with, species of the St. Cassian beds (Laube). 2. JURASSIC. The belt of Trias in England (see map, page 694) is succeeded on the eastward by approximately parallel and interlocking belts of Lias and Oolyte, and then follows the Cretaceous. This position of the Jurassic areas between the Triassic and Cretaceous is common over Europe. In France and Germany, south of the broad coast region of Tertiary and Cretaceous, comes first the Jurassic next to the Cretaceous, and then the Triassic. The British Jurassic belt, which reaches the Channel at Lyme-Regis, reappears in France, and is continued along by the inner side of the Cretaceous, about the so-called Paris Basin, and also in Hanover, in northwestern Germany. Further, Jurassic areas border the inner side of the Triassic. From west-central France they extend southeast to the Mediterranean, and from east-central southeast to the Juras ; and a long Jura-mountain belt, of northeastward course, reaches far into northern Bavaria and Germany. Jurassic rocks occur also along both sides of the Alps, and extend on through the Austrian Alps ; and after an interruption about Vienna, appear again in the Carpathians. MESOZOIC TIME TRIASSIC AND JURASSIC. 775 They outcrop along the Apennines, the Pyrenees, and east-central Spain. They cover large areas in central and northern Russia. The beds have a small development along the Alps compared with the Triassic; but the fossils and rocks show, by their kinds, that the great continental sea was here of unusual depth and purity. In England the subdivisions of the Jurassic series are as follows : 1. Liassic Group. (1) The LOWER LIAS, consisting of clays, shales, and gray limestone, and about 900 feet thick. (2) The MIDDLE LIAS, or Marlstone, a coarse shaly argillaceous and ferruginous limestone with sand-beds and clays ; 200 to 350 feet thick. (3) The UPPER LIAS, consisting of clays and shales, and containing lime- stone concretions ; 200 to 300 feet thick ; with the Midford sands in southern England about 200 feet. The jet of the Yorkshire coast is a compact variety of coal from the Upper Lias. These subdivisions were named in France by D'Orbigny : (1) the Sinemurian, from the Latin word for the town of SSmur ; (2) the Liassian ; and (3) the Toarcian, from Thouars, in western France. 2. Oolytic Group. (1) The LOWER OOLYTE. Divided into (1) the Inferior Oolyte, which includes the sandstones or Dogger of York- shire and the Cheltenham beds the Bajocian ; and (2) the Great or Bath Oolyte the Bathonian, including (a) the Fuller's earth, or clay-beds of varying thickness up to 400' in Dorsetshire; (&) the Stonesfield slate, a thin-bedded limestone in Oxfordshire, and above it ; (c) the Forest Marble, consisting of sandy and clayey layers with Oolyte ; and (d) the Cornbrash, a coarse shelly limestone. At Brora, on the east coast of northern Scotland, there is a coal-bed 2' thick, overlaid by beds containing Middle Oolyte fossils. In Yorkshire, the Inferior Oolyte contains estuarine beds with thin seams of coal and many remains of plants. (2) The MIDDLE, or OXFORD OOLYTE. Divided into (1) the Callovian, consisting of the Kellaways rock ; (2) the Oxfordian, calcareous sandstone and the Oxford clay ; and (3) the Corallian, made up of the Coral rag or Coralline Oolyte, 10' to 120', with more or less of calcareous grit, 5' to 80'. (3) The UPPER, or PORTLAND OOLYTE. Divided into (1) the Kimmeridgian, or Kimmeridge clay, having ferruginous con- cretions in the lower division, called " doggers " ; (2) the Portlandian, or the Port- land stone, including marlytes and limestone, in part oolytic, with fresh-water beds ; and (3) the Purbeckian, or Purbeck beds, well displayed in Dorsetshire, mostly shales with some limestone at middle which is partly of marine origin, 10Q' to 400' thick, and affording remains of numerous Insects and Mammals. The "Portland dirt-bed" is at its base. In Europe other subdivisions have been introduced, for which see page 790. 776 HISTORICAL GEOLOGY. The "Black Jura" of Germany corresponds to the Lias; the "Brown Jura" or "Dogger" to the Lower Oolyte and Callovian; and the Upper or White Jura, or Malm, to the rest of the Middle and the Upper Oolytes, from the Callovian to the Portland beds inclusive. To the Kimineridgian group belongs the fine-grained lithographic limestone of Solenhofen at Papenheim, in Bavaria, near Munich, about 80' thick, noted for its wonder- fully perfect preservation of fossil Crustaceans, Squids, Insects, impressions of birds' feathers and of wings of Pterodactyls. In Peninsular India, in the district of Cutch, the beds referred to the Jurassic have a thickness of 6000', the lower chiefly marine, and the upper as prominently fresh- water. Outside of the peninsula the Jurassic occurs in the Salt Range and northwest Himalaya, with characteristic fossils. In Australia, Jurassic rocks with many fossils have been observed in Western Australia, of the periods of the Middle and Upper Lias and Lower Oolyte; and in Queensland, of the Upper Oolyte (C. Moore, Q. J. G. Soc., 1870). Aucella-bearing beds have been observed, as C. A. White states in Becker's Report (see page 835), near Moscow, in Petschora-land, near the Caspian, in northern Siberia, in Nova Zembla, Spitzbergen, in the Kuhn Islands near the east coast of Greenland, in southern India, in New Zealand, and in Brazil ; and they have been referred by most authors to the Jurassic ; but Professor Eichwald makes them Neocomian, and Zittel refers those of New Zealand to the Jura or Lower Cretaceous. LIFE OF THE FOREIGN JURASSIC. The Lias and Oolyte of Britain and Europe afforded the first full display of the marine fauna of the world since the era of the Subcarboniferous. Very partial exhibits were made by the few marine beds among the Coal- measures; still less by the beds of the Permian, and far less by the Triassic. The seas had not been depopulated. The occurrence of over 4000 invertebrate species in Britain in the single Jurassic period is evidence, not of deficient life for the eras preceding, but of extremely deficient records. Further, this meagerness in American records continued until the Cretaceous period. Moreover, in order to put together rightly the American and Euro- pean records, it is necessary to note that the events of the epochs of the Lias and Lower Oolyte, with their vertebrate life, have their place, according to present knowledge, be- fore those of the Ameri- can Atlantosaurus bed s ; that is, between those of the Middle Oolyte and of the Triassic. PLANTS. The land plants of the Juras- sic period were mainly Cycads, Conifers, Ferns, Fig. 1268, Section from near Lullworth Cove, showing stumps of trees and Equisetd, as in the in the Portland "dirt-bed" ; 1269, stump of the Cycad, Mantellia mega- T j pnvp <, aTlf l lophylla (x A)- Buckland. TiaSSlC. JjCa stems occur in many strata, and especially in the Lower Oolyte in the Yorkshire beds and in the 1268. MESOZOIC TIME TRIASSIC AND JURASSIC. 777 Stonesfield slate, chiefly near Woodstock, where have been found over 80 spe'cies of Ferns, nearly 20 of Conifers, and 40 of Cycads. The Middle and Upper Oolyte have afforded about 16 other species. The Conifers are of the genera Taxites, Thuyites, Cupressites, Araucarites, names which express their modern relations. There were also Endogens of the Arum and Pan- danus families ; but no Angiosperms or Palms. The " dirt-bed " at the base of the Pur beck has afforded stumps of Cycads (Fig. 1268), including three species of Mantellia, one of which is shown in Fig. 1269. There is also a species of Pine (Pinites), besides a few other plants. INVERTEBRATES. Siliceous Sponges, both the Hexactinellid (Fig. 1270) and Lithistid kinds, were very common in the Middle and Upper Oolyte, and so-called sponge-beds occur in the European Oolyte at different levels. Polyp-corals were of many kinds, of the modern Hexacoralla type (hav- ing the rays a multiple of 6). The Corals flourished like the species of 1272. 1270. 1271. SPONGE, of the Oolyte. Fig. 1270, Tremadictyon reticulatum. POLYP-CORALS, of the Oolyte. Fig. 1271, Mont- livaltia caryophyllata ; 1272, Isastrsea oblonga. D'Orbigny. modern coral reefs (1) in the pure ocean waters, and (2) many too in the shallow waters of the ocean's borders, as about modern coral reefs. For (1) the limestones make several alternations with the sediments, clays, and sand-beds of the sea margins ; and (2) only the purer limestones contain the corals. They abound in England in some beds of the Lias, in both sections of the Lower Oolyte, the Inferior and the Great Oolyte, in the Corallian of the Middle Oolyte, but are absent from the Kellaway beds or Oxford clay of the Middle, and from all of the Upper Oolyte beds in England, excepting a single species, Isastrcea oblonga (Fig. 1272), in the Portland limestone. The reef species of the Oolyte may have flourished at greater depths than those of existing reefs, but appear not to have been, in general, abyssal species. The most of the species of the Lias are of the genera Montlivaltia (M. caryopliyllata^ Fig. 1271, from the Bath Oolyte), Thecosmilia, Astrocoenia, Isastrcea; and excepting Astroccenia these, with Thamnastrcea, are the most prominent genera in the Lower Oolyte. 778 HISTORICAL GEOLOGY. The Isastrcea, Thecosmilia, and Thavnnastrcea corals are massive kinds. Etheridge's tables for British fossils in 1885 give the number of Jurassic species, in all, 236, and. of these the genera mentioned contain : Total Astroccenia 14 Isastraea 24 Montlivaltia 44 Thecosmilia 21 Thamnastraea 27 Lias Lower Ob'lyte Middle Oolyte Upper Oolyte 14 10 18 4 1 25 18 1 14 6 1 21 23 3 Echinoderms were in profusion, as in existing coral seas. Crinoids were numerous of the genera Pentacrinus, Apiocrinus, and others. f Pentacrinus (Extracrinus) Briareus (Fig. 1278) is one of the common and most re- markable of the species in the Lias ; a bed in the Lower Lias is largely 1273-1278. 1273 1278 1277 ECHINODERMS. Fig. 1273, Apiocrinus Roissyanus (x |), Oolyte, the middle part of the stem omitted; 1274, Saccosoma pectinata, Oxfordian ; 1275, Pseudodiadema seriale ; 1276, Cidaris Blumenbachii ; 1277, spine of the last ; 1278, Pentacrinus (Extracrinus) Briareus. MESOZOIC TIME TRIASSIC AND JURASSIC. 779 made of it and shells of Gryphcea arcuata (Etheridge) . Apiocrinus Roissyanus D'Orb. (Fig. 1273) is from the Middle Oolyte of Europe. Saccosoma pectmata Ag. is a Comatulid, or free Crinoid, from the Oxfordian group. Of Echinoids, the genera Cidaris (Fig. 1276), Hemicidaris, Pseudodiadema, and Hemapedina include the larger part of the species. Pseudodiadema seriale (Fig. 1275) is from the Lower Lias. Brachiopods of the spire-bearing genera had their last species in the Jurassic period. These excepted, the Jurassic Brachiopods were mostly of 1279-1285. 1280 1282 BRACHIOPODS. Figs. 1279, 1280, Cadomella Moorei (x f) ; 1281, same, nat. size ; 1282, Spiriferina Walcotti, Lias ; 1283, Terebratula digona, Great Oolyte ; 1284, T. diphya, Tithonian ; 1285, Ehynchonella inconstans, Kim- meridge. the Terebratula, Rhynchonella, TJiecidium, Lingula, and Discina families, which have also living species. Lamellibranchs were of several new genera. Gryphcea (Figs. 1287, 1290) , of the Oyster family, having an incurved beak, commenced in the Lias and 1286. 1287. LAMELLIBRANCHS. Fig. 1286, Lima gigantea (x ), Lias ; 1287, Gryphaea incurva (x|), Lias. continued into the Cretaceous. Fig. 1287, G. incurva, is from the Lias, and 1290, G. dilatata, is from the Oxfordian beds. Exogyra (Fig. 1289), also of the Oyster family, is another characteristic genus, but more so of the Ore- 780 HISTORICAL GEOLOGY. taceous ; the beak is twisted to one side, as is implied in the name. Trigonia (Fig. 1291), the name alluding to the somewhat triangular form, has over 100 Jurassic species. Another peculiar type common in the Middle Oolyte 1288-1293. 1294. LAMELLIBEANCHS. Fig. 1288, Ostrea Marshii, Lower Oolyte; 1289, Exogyra virgula, Kirameridgian ; 1290, Gryphsea dilatata, Callovian ; 1291, Trigonia clavellata, Corallian ; 1292, Astarte minima, Corallian ; 1293, Diceras arietinuin, Diceratian. in the northern Alps is that of Diceras (Fig. 1293), a species in which the beak of each valve is curved spirally ; it is related to the modern Chama. Of existing genera having many Jurassic species there are Ostrea, Pecten, Lima (Fig. 1286), Astarte (Fig. 1292), Lucina, Corbula, Nucula, Pholadomya, and many others. Gastropods were very numerous. The number of species found in British Jurassic rocks alone is nearly 1000; and of these over 10 per cent were of the old genus Pleurotomaria, the number being larger than for all preceding time. It was the culminating time for the type ; only two living species are known. Other genera of many species dating from the Paleozoic, and also modern, are Trochus, Turbo, Patella, Natica, which comprise 25 per cent of the British Jurassic Gastropods ; and among the many of Mesozoic origin, Cerithium has 10 per cent of all the GASTROPOD. Fig. 1294, Neri- nea Goodhallii, Corallian. MESOZOIC TIME TRIASSIC AND JURASSIC. 781 species, and Chemnitzia 20 per cent (Etheridge) . The genus Nerinea, having one or more ridges in the spiral cavity (Fig. 1294) is confined to the Oolyte, and the Cretaceous period. Cephalopods of the Ammonite type have an enormous expansion in the period ; 250, or three-fifths of the British species, occur in the Lias. Figs. 1296, a are from the Lower Lias ; 1295 and 1297 from the Middle Lias ; 1295-1297. 129T CEPHALOPODS (Ammonites) of the Lias. Fig. 1295, Pleuroceras spinatum ; 1296, a, Coroniceras Bucklandi ; 1297, ^Egoceras capricornus. 1298, from the Inferior Oolyte ; 1299, from the Middle Oolyte. The last two figures have the aperture unbroken ; and in 1299 it is much prolonged on either side. 1298-1299. 1299 1298 CEPHALOPODS of the Oolyte. Fig. 1298, Stephanoceras Humphriesianum ; 1299, Cosmoceras Jason. Besides the Cephalopods with external chambered shells (Tetrabranchs), the Belemnites (Dibranchs) (page 424) were of many species. Figs. 1302, 1303, represent the bones or osselets of two species, in their ordinary broken state; and Figs. 1300, 1301, an unbroken one, in two different positions. 782 HISTORICAL GEOLOGY. Fig. 1305 represents the animal of an allied genus, called Belemnoteuthis. The ink-bags of Belemnites are sometimes found fossil (Fig. 1304), and 1800 1300-1304. 1801 1802 1802 a 1304 CEPHALOPODS. Fig. 1800, Complete osselet of a Belemnite, side view, reduced ; 1301, dorsal view ; 1302, a, Belemnites paxillosus, Middle Lias ; 1303, B. clavatus ; 1304, ink-bag. Buckland states that he had drawings of the remains of extinct species made with their own ink. 1305. Fig. 1305, Belemnoteuthis antiqua (x J), of the Oxford clay. From Mantell. Crustaceans included forms of modern aspect, and among them species of the highest of the divisions of Crabs, the Triangular Crabs Palseinachus MESOZOIC TIME TRIASSIC AND JURASSIC. 783 of Woodward. Fig. 1307 is one of the Macrurans from Solenhofen, and 1308, an Isopod related to the modern Oniscus, from the Purbeck beds of England. A species of Astacus, or Lobster, is reported from the Lias. Fig. 1310, though Spider-like, is a Stomapod Crustacean. 1306-1310. ARTICULATES. Fig. 1306, Libellula ; 130T, Eryon arctiformis; 1308, Archaeoniscus Brodiei ; 1809, elytron or wing-case of Buprestis ; 1310, Palpipes priscus. Insects of all the prominent tribes, even those of Dipters and Hymenopters, occur as early as the Lias ; and the Hymenopters belong to one of the higher divisions, that of the Ants. A Lias species of Ant is the Palceomyrmex prodromus of Heer, from Switzerland. Two other related species were described by Woodward from the Purbeck of England. Fig. 1306 represents a Dragon-fly, and 1319 a Beetle's wing-case (a Buprestis), both from Solen- hofen ; and another Dragon-fly, Libellula Brodiei, is from the Upper Lias of England. VERTEBRATES. The Jurassic Vertebrates included Birds, as well as Fishes, Reptiles, and Mammals. 1. Fishes. The Fishes were Ganoids and Selachians. Two genera are illustrated in Figs. 1311, 1312. Pycnodus had many species, and also, among Selachians, Hybodus, Acrodus, Strophodus ; and among Ganoids, Lepidotas, and others. The Ganoids most nearly related to the Teleosts are those of the Amia family, of Pike-like form, species of which occur at Solenhofen. The Amioids have been referred to the Teleosts, but are now regarded as true Ganoids. 784 HISTORICAL GEOLOGY. 2. Reptiles. Sea-Saurians. The skeleton, in restored form, of Ichthyo- saurus communis is represented, T ^ the natural size, in Fig. 1313 ; the head, 1311-1312. 1311 GANOIDS. Fig. 1811, Dapedius, restored (x &), Lias; 1311 a, scales of same; 1312, Aspidorhyncus (x ), Solenhofen. reduced to -$, in 1314 ; one of the teeth, natural size, in 1316 ; and a vertebra in 1315. The Fish-like biconcave vertebrae suggested the name of the group, from tx$ v ' s ? fish) an d o-avpos, lizard. 1313-1318. 1C REPTILES. Fig. 1313, Ichthyosaurus communis (x r J 5 ) ; 1314, head, id. (x ^,) ; 1315 , b, view and section of vertebra, id. (x ) ; 1316, tooth, id. (x }) ; 1317, Plesiosaurus dolichodeirus (x ^) ; 1318 a, 6, view and section of vertebra of same. Of Ichthyosaurians, 25 species have been described from the British rocks ; and of these, 15 were found in the Lias, and 7 in the Upper Jurassic (Etheridge). MESOZOIC TIME TRIASSIC AND JURASSIC. 785 A restoration of a Plesiosaur, a long-necked, somewhat Turtle-like, Sea- Saurian, reduced to -^ the natural size, is given in Fig. 1317 ; and figures of the vertebrae here also biconcave in 1318 a, 6. Fig. 1319 represents another species, Plesiosaurus macrocephalus Owen, as it lay in the rocks. The figures illustrate the long Snake-like neck of the species, the short body, and 1319. REPTILE. Fig. 1319, Plesiosaurus macrocephalus (x &). Buckland. the character of the paddles. Pliosaurus is another genus. Out of 47 British species of Plesiosaurids, 22 occur in the Lias, all but one pertaining to the genus Plesiosaurus. The group continues into the Upper Jurassic, which has afforded, in Great Britain, 12 species of Plesiosaurus, six of Pliosaurus, and one of Dinotosaurus (Etheridge). The Coprolites (fossil excrements) of the Saurians are not uncommon ; one is represented in Fig. 1322. They are sometimes silicified, and, notwith- standing their origin, are beautiful objects when sliced and polished. Dinosaurs. The earliest discovered of the Carnivorous Dinosaurs was the Megalosaurus Bucklandi (1824). The length of the skull was perhaps two feet, and that of the body probably 30 or 40 feet. It appeared in the Lower Lias and continued through to the Upper a length of survival for such a species that is most extraordinary, and indicates high supremacy among its cotemporaries if the apparent short life limit of other species is DANA'S MANUAL 50 786 HISTORICAL GEOLOGY. not merely poor luck as to becoming fossilized. The fore limbs were much the shorter pair, as in other species of the group. In contrast with the Megalosaurs there was the strongly Bird-like Compsognathus, from Solenhofen, C. longipes of Wagner, one of the smaller Dinosaurs, the length not over two feet. The feet were all three-toed ; the fore limbs very short, the hinder long, with the femur shorter than the tibia ; the neck long and slender ; the head small, but well armed with teeth, characters indicating, as Huxley states, a strong resemblance to the Bird not only in general form, but probably also in an erect or nearly erect posture in walking. It is perhaps related to Hallopus Marsh, of the North American Jurassic. 1320. Mystriosaurus Tiedemanni. Among Herbivorous Dinosaurs, of the Sauropod division, the largest European species known was the Cetiosaurus of Owen (1841), related to the American Morosaurus. C. Oxoniensis was 40 or 50 feet long, "not less than 10 feet in height when standing, and of a bulk in proportion." The femur is 64 inches long. -Cetiosaurian remains occur in the Lower and Upper Oolyte, and. five species have been described. 1321. 1322. PXBBOSAUB. Fig. 1321, Pterodactylus crassirostris (x |) ; 1322, Coprolite. Buckland. Fig. 1321, from D'Orbigny ; 1322, Another genus of gigantic Herbivorous Dinosaurs is the Iguanodon of Mantell, which first appears in the Middle Oolyte ; it was of the Ornithopod group. MESOZOIC TIME TRIASSIC AND JURASSIC. 787 The Omosaurus armatus of Owen (1875) was Stegosaurian, and perhaps, as Marsh suggests, a species of the genus Stegosaurus; and he observes that the Scelidosaurus of Owen is an allied form. Crocodilians, Lacertians, Chelonians. The Crocodilians were represented by Teleosaurs, species having the size and slender head of the Gavial of the Ganges, but with biconcave vertebrae. Two species occur in the Upper 1323-1325. 1325 PTEKOSATTB. Fig. 1323, Rhamphorhynchus phyllurus (x ) ; 1324, caudal oar (x t) ; 1325, restoration (x $). All from Marsh. Lias of England, and five others in the Lower and Upper Oolyte. Fossil eggs from Cirencester are suspected to be Teleosaurian (Buckman). The Mystriosaur (Fig. 1320) is a related species from the Lias of Europe. A species of Lizard, referred to the genus Lacerta, occurs in the Lower Oolyte of England. Tortoises (Chelonians) are found in the Oolyte ; and a terrestrial species, Testudo Stricklandi Phillips, in the Stonesfield slate. 788 HISTORICAL GEOLOGY. 1326. Pterosaurs. The Pterosaurs, or flying Lizards, have hollow bones like Birds. The genera Dimorphodon, characterized by a long tail, and Ptero- dactylus, by a very short one (Fig. 1321), occur in the Lias, and JRham- phorhynchus (Figs. 1323-1325) in the Stonesfield slate and at Solenhofen. Fig. 1321 represents the skeleton (^ natural size) of Pterodactylus crassi- rostris; it was a foot long, and the spread of the wings about three feet. Fig. 1323 is the fthamphorynchus phyllurus of Marsh, from Solenhofen, Eich- stadt, Bavaria, and 1325 a restoration; its long slen- der tail ends in a broad oar (Fig. 1324). The fine specimen in the Yale Mu- seum, New Haven, Conn., has an impression of the wing membrane, showing it to be without feathers. 3. Birds. Specimens of birds have been found in the lithographic limestone of Solenhofen, with nearly complete impressions of the feathers and also well-pre- served bones of the limbs, heads, and most other parts of the skeleton. They per- tain to a single species, the Archceopteryx macrura of Owen. A single feather was first found in 1860. This was followed, two years later, by the dis- covery of a nearly entire skeleton, but wanting the head; it was described by Owen. The specimen is now in the British Museum. Later, a third and still more complete skeleton was ob- tained, and this is in the BIRD. Archaeopteryx macrura (x $). W. Dames. Museum at Berlin. It has (1) in the jaws on either side, in sockets, 13 Keptile-like teeth; (2) a long vertebrated tail, having 20 vertebrae, each carrying a pair of long feathers ; (3) wing bones like those of the fore leg of a normal three-toed Eeptile, having claws at the extremity; (4) four-toed hind limbs, Bird-like in adaptation to biped loco- MESOZOIC TIME TRIASSIC AND JURASSIC. 789 motion; (5) the vertebrae biconcave, as in Fishes and many Mesozoic Reptiles; (6) a small pelvis with the bones separate, and no elongation of the pubes. As at the present time the breed of fowls having feathered legs is produced by breeding from fowls having the legs scale-covered, thus sub- stituting feathers for scales, the succession of Birds to Reptiles as regards this particular point is not so strange as, at first thought, it might seem to be. 4. Mammals. Jurassic Mammals have been found in the Stonesfield slate, Lower Oolyte, and in the Middle Purbeck beds. As in America, the species are probably Marsupials, and Monotremes. Among the species at the former locality are Amphilestes Broderipi (Fig. 1327) and Phascolotherium 1327-1328. 1328 MAMMALS. Fig. 132T, Amphilestes Broderipi (x 2) ; 1328, Phascolotherium Bucklandi (x 2). Pictet. Bucklandi (Fig. 1328). The genera Plagiaulax, Microlestes, and Tritylodon are supposed to be Monotreme. The following figures of jaw bones of the British speoies, of natural size, showing the dentition, derived chiefly from Owen's papers, are copied from Osborn's review of the Mesozoic Mammalia. 1329-1345. Fig. 1829, Amphilestes ; 1330, Amphitylus ; 1331, Phascolotherium ; 1332, Triconodon mordax ; 1333, Peramus ; 1334, Spalacotherium ; 1335, Peralestes ; 1336, Peraspalax; 1337, Leptocladus; 1338, Amblotherium ; 1339, Phascolestes ; 1340, Achyrodon ; 1341, Stylodon ; 1342, Athrodon ; 1343, Bolodon ; 1344, Plagiaulax minor ; 1345, Stereognathus. All natural size. 790 HISTORICAL GEOLOGY. Characteristic Species. 1. Lias. 1. LOWER SINEMURIAN. Ammonites (^Egoceras) planorbis, A. ( Coroniceras) Buck- landi, Ostrea Liassica, Gryphcea arcuata, Lima gigantea, Hippopodium ponderosum, Spiri- ferina Walcotti, Isastrcea Murchisoni, Pentacrinus (Extracrinus) Briareus, Ichthyosaurus, Plesiosaurus. The " White Lias " or Hettangian, beneath the Sinemurian, or at the top of the Rhaetic, contains Ammonites planorbis, A. Burgundies, Cardinia Listen, C. concinna, Pecten Valoniensis. 2. MIDDLE LIASSIAN. Ammonites (Amaltheus} spinatus, A. (A.} ibex, A. (^Egoceras} Jamesoni, Belemnites paxillosus, B. clavatus, Gryphcea obliqua, Avicula incequivalvis, Inoceramus substriatus, Plicatula spinosa, Pentacrinus subangularis. 3. UPPER TOARCIAN. Ammonites (Harpoceras) serpentinus, A. (Harpoceras) bifrons, A. (Lytoceras) Jurensis, A. (Harpoceras') radians, Nautilus Jurensis, Belemnites vulgaris, Leda ovum, Posidonomya Bronni, Ehynchonella pigmcea, Cadomella, Spiriferina, Pseudo- diadema Moorei, Extracrinus Briareus, Ichthyosaurs, Plesiosaurs, Teleosaurus Chap- manni (at Whitby). 2. Oolyte. 1. LOWER OOLYTE. (1) Bajocian. The subdivisions recognized in England are those of Ammonites (Harpoceras} Murchisonce, Lower ; of Stephanoceras Humphriesianum, and Cosmoceras Parkinsoni, Upper. In Europe : (a) Aalenian, with Amm. (Harpoceras} Murchisonce, Ehynchonella subangulata, Terebratula perovalis, T. fimbria, Pecten lens, Pholadomya fidicula. (6) Bajocian, with Amm. (Stephanoceras) Humphriesianus, A. (Cosmoceras) Parkinsoni, Astarte obliqua, Trigonia costata, Gryphcea sublobata (Gryphcea teds), Ostrea Marshii, Rhynchonella spinosa, Terebratula perovalis. (2) Bathonian. (a) Vesulian or Fuller's Earth, with Amm. discus (and up to Corn- brash), A. Herveyi (and up to Forest Marble), A. ferrugineus, Anabacia hemisphcerica, Pecten vagans, Ostrea acuminata, Ehynchonella varians. (b) Bradfordian, or Great (or Bath) Oolyte, with Amm. macrocephalus, A. aspidioides, Ostrea Marshii, Pecten lens, Ehynchonella decorata, E. concinna, Megalosaurus, Cetiosaurus, Pterodactylus, Wald- heimia digona, Steneosaurus ; and in the Stonesfield slate, at the base, with many plants, Ostrea Soioerbyi, Ehynchonella obsoleta, Gervillia acuta, Ichthyosaurus, Plesiosaurus, Teliosaurus, Ehamphorhynchus, Testudo Stricklandi, Chelys Blakei, Mammals. In Russia the Oxford Oolyte is overlaid by beds called the Volgian. 2. MIDDLE OOLYTE. (1) Oxfordian. (a) Callovian or Kellaways Rock, with Amm. Gowerianus, A. macrocephalus, Belemnites Oweni, B. hastatus, Gryphcea bilobata, G. dilatata, Trigonia paucicosta, Terebratula digona. (b) Oxfordian or Oxford Clay, with A mm. Lamberti (up to Kimmeridgian), A. Marice, Trigonia clavellata, Pecten vagans, Avicula incequivalvis, Ehynchonella socialis. (2) Corallian. (a) Argovian, Sponge-bearing beds, Scyphian-Kalk, and those of Amm. canaliculatus. (b) Corallian, divided into Eauracian or Glyptician, with Glypticus hieroglyphicus, Amm. bimammatus, Thecosmilia annulata. (c) Isastrcea explanata and Diceratian, with Diceras arietinum, Nerinea Defrancii. The Coral Rag and Corallian Oolyte of the Corallian contain Amm. plicatilis, Thamnastrcea gregaria, T. concinna, Cidaris jlorigemma, Hemicidaris intermedia, Pseudodiadema hemisphaericum, Avicula ovalis, Lima rudis, Perna myliloides; and the underlying Lower limestones, Amm. cordatus, Avicula ovalis, A. expansa, Pecten fibrosus. 3. UPPER OOLYTE. (1) Kimmeridgian. (a) Sequanian or Astartian, with Astarte minima, A. supracorallina, A. gregaria, Ostrea deltoidea, Ehynchonella corallina, Amm. mutabilis, A. decipiens, A. tcnuilobatus, Pseudodiadema hemisphcericum, Cidaris MESOZOIC TIME TRIASSIC AND JURASSIC. 791 Jlongemma, C. Blumenbachii, Apiocrinus Meriani. (6) Pteroceriarij with Amm. acanthi- cus, Pterocera oceani, P. ponti, Nerinea depressa, Waldheimia humeralis. (c) Virgulian, with Gryphcea virgula, Trigonia gibbosa, Terebratula diphya, Pholadomya multicostata, Thracia depressa. (d) Bolonian, with Amm. gigas, A. suprajurensis, A. biplex, Trigonia incurva, Cyprina Brongniarti. (2) Portlandian or TUJwnian. (a) Portlandian or Nerinean, Amm. gigas, Trigonia gibbosa, Gryphwa virgula, Ostrea solitaria, Lucina Portlandica, Perinea trinodosa, Pterocera oceani. (6) Purbeckian, with Corbula inflexa, C. Forbesiana, Cardium Purbeckense, Terebratula diphyoides, Hemicidaris Purbeckensis, Astrcea distorta, Insects, Mammals. The Tithonian group in the eastern Alps includes a coral limestone near Salzkammer- gut, and the Diphya limestone abounding in Terebratula diphya ; also Aptychus beds ; and some of the limestones contain many Ammonites, Phylloceras ptychoicum, and others. The Jurassic beds of Cutch, in India, contain, in the Lower Oolyte, Astarte com- pressa, Corbula pectinata, Ehynchonella concinna ; in the Middle Oolyte, Amm. (Stepha- noceras) macrocephalus, A. (Peltoceras) athleta, Terebratula biplicata, T. sella, and many other Ammonites, many Belemnites, etc. ; in the Upper Oolyte, Amm. (Phylloceras} ptychoicus, and many other species. Also many species of plants, as Sphenopteris arguta, Alethopteris Whitbyensis, Otozamites contiguus. The Portlandian beds afford Trigonia Smeei and T. ventricosa, the latter also a South African species ; also jaw of a Plesiosaur. The Upper Jurassic of the Zanskar area in the central Himalayas has afforded Belemnites clavatus, Ammonites macrocephalus, A. Parkinsoni, A. biplex, Trigonia costata, and other species. The Hundes area in the Tibetan Himalayas also has many Jurassic species. (Cf. Medlicott and Blandford, Geology of India, vols. i. and ii., 1879, and second edition by Oldham, 1894.) In western Australia, 20 species of Liassic and Oolytic fossils are identical with British species : 3 of the Ammonite group, Nautilus semistriatus and Gresslya donaci- formis of the Upper Lias ; Myacites Liassinus of the Middle Lias ; and 2 of the Ammonite group, with Belemnites canaliculatus, Cucullcea oblonga, Pholadomya ovulum, Avicula Munsteri, A. echinata, Pecten cinctus, P. calvus, Lima proboscidea, L. punctata, Ostrea Marshii, Ehynchonella variabilis, Cristellaria cultrata, of the Oolyte (C. Moore). CONTINENTAL RESEMBLANCES AND CONTRASTS IN THE TRIASSIC AND JURAS- SIC PERIODS; CLIMATE. The Triassic formation is alike over a large part of Europe and America in kinds of rocks, in paucity of fossils, and in evidences of shallow-water origin, and of largely brackish water, if not fresh. The continental surface in each case was very near or above the water level over large areas ; and it oscillated between brackish or fresh-water flats and barren or half-barren salt-water flats or sea-border salt-pans. The European exception is in the Mediterranean region. Not only is this general fact true for the two conti- nents mentioned, but also for India, South Africa, and Australia, or the continental regions in the opposite hemisphere. This so general prevalence over large parts of the continents of slight submergence, too slight for abun- dant remains of marine life, although this life must undoubtedly have been as profuse in kinds as in any earlier or later era, indicates general and synchronous movements in the earth's surface, and correlate progress in continental growth. The Jurassic period was, in contrast, a period of somewhat deeper and clearer seas, sustaining at many levels abundant life, 792 HISTORICAL GEOLOGY. but still with wide differences between the continents as to the extent of such seas. It is an interesting fact, bearing on the conditions under which the Liassic beds were made, and the facility with which the clear open waters of a fossiliferous limestone horizon may change to the confined waters of a sea border, that a bed of limonite or ferruginous limestone occurs in the Lower Lias northwest of Lincolnshire, England, which is 27 feet thick, and in the Upper Lias, near Bath, two feet thick ; on the continent, in Lorraine, in the Upper Lias, 10 to 50 feet thick, containing Ammonites, a Gryphcea, Trigonia navis, etc. ; in Auxois, France, near the base of the Lower Lias overlying a bed of "lumachelle" limestone; and, as stated by C. Moore, in western Australia, in the Middle Lias, a very ferruginous limestone, which on analysis gave 49 to 56 per cent of metallic iron. Moore goes so far as to regard the ferruginous bed of Australia as proof of Liassic age ; the associated fossils are much better evidence. But with all the resemblance in physical conditions between Europe and America, there was a remarkable contrast in the abundance of marine life in the continental seas. This contrast was especially great in the Jurassic period. The number of species of Jurassic Invertebrates thus far described from the American rocks is less than 250 ; very few of these are Corals, 17 are Cephalopoda, 5 Echinoderms, 17 Gastropods, 113 Lamellibranchs (Whitfield). In the Jurassic of Great Britain alone the number of known marine species, as stated by Etheridge (GfeoL, 1885), is over 3900 ; those of Corals 236, Echinoderms 208, Ammonites 417, Belemnites 112, Gastropods 988, and Lamellibranchs 1319. More study may quadruple the number of American species ; but this will little diminish the contrast. As indications of the climate of the Triassic and Jurassic periods, there are these pertinent facts from the Arctic regions : that the species Ceratites Malmgreni, Ammonites Gaytani, Nautilus Nordenskioldi, Halobia Lommeli, H. Zitteli were living in the Spitzbergen seas during the Triassic period; and Ammonites (Harpoceras) M'Clintocki, Monotis septentrionalis, and species of Pleurotomaria and Nacula, about Bathurst Island, Exmouth Island, and Prince Patrick Island, probably during the Jurassic period, species that have closer relations to European than to American species (Haughton, Waagen) that Iclitliyosaurs were living in Triassic or Jurassic time about Exmouth Island (77 16' K, 96 W.), their remains having been found on this island by the Belcher Expedition ; and that other Ichthyosaurs existed in the Spitz- bergen seas, probably during the Triassic period, remains of two having been found by Nordenskiold, which have been named, by Hulke, Ichthyosaurus Nordenskioldi and /. Polaris ; that another Saurian " probably a Dinosaur, allied to the Anchisauridae," inhabited the region about Bathurst Island, Captain Sherard Osborn having brought home a vertebra, which has been made a basis of a species named by A. L. Adams Arctosaurus Osborni. The continent of North America, as already explained (page 47), is peculiar in climatal situation. It has the Gulf Stream warm with tropical MESOZOIC TIME TBIASSIC AND JURASSIC. 793 heat, flowing northward and eastwardfciear its eastern border, but not much for the warming of North American waters north of Cape Hatteras ; its heat is carried on for distribution over northern and western Europe and the Arctic seas. Heading off the Gulf Stream from the American coast north of Hatteras, there flows from the north a current of Arctic waters, that makes its escape from the polar basin by the only large passage way out the way leading into the Atlantic ; and these cold waters are like a cold wall along the eastern side of the continent. The American coast has a means of pro- tection against the polar current, through an elevation of the border sufficient to make Newfoundland a peninsula by closing the Strait of Belle Isle. Moreover, if the elevation were only 500 feet, the eastern cape, around which the cold current would be forced to flow, would be set 250 miles east of its present position. On the Pacific side a cold northwestern current follows the coast of North America from Alaska southward, as part of the normal oceanic circulation. Thus at the present time North America has relatively cold waters along both its eastern and western shores. Hence there is reason enough for the paucity of its existing marine faunas. In Paleozoic time this contrast with Europe did not exist, or only to a small degree ; for the Paleozoic species even exceed in numbers those of Europe. The Arctic basin was probably open widely in all directions. But in the early Mesozoic it must have become the closed basin which it now is, with its only free outlet into the Atlantic ; and in this way the continent of North America was thus early put between northern cold Atlantic and cold Pacific currents. The actual difference of temperature between the waters of the North American and European sides of the Atlantic in the Triassic and Jurassic periods is uncertain, because no marine fossils of these periods have been found on the American side. On the European side the presence of warm seas is proved by the profusion of marine species and by their kinds. The coral reefs of the Oolyte in England consist of corals of the same group with the reef-making species of the existing tropics. This favors the conclusion that the British waters, and nearly all the European, were within the coral- reef temperature limit ; that is, the line along which 68 F. is the mean tem- perature of the year. The Oolytic isocryme of 68 F. (see map, page 47), accordingly, would have had nearly the position of the line of 44 F. in exist- ing seas, but with a little less northing and more leaning to the eastward. The Gulf Stream was the probable cause of this long northward extension of warm waters in Jurassic time. Further, in Europe, according to Neumayr, differences in the climate of the later Jurassic are indicated by the distribution of fossil Invertebrates. The Mediterranean Province, or that of southern Europe, including the regions of the Alps and Carpathians, Italy, Spain, and the Balkan peninsula, is characterized by Ammonites of the genera Phylloceras, Lytoceras, and Simoceras, with the Brachiopod Terebratula diphya. The Middle European Province, comprising the region of the Juras, France, Germany, England, 794 HISTORICAL GEOLOGY. and the vicinity of the Baltic, has f ey species of Phylloceras and Lytoceras, and very many of Harpoceras, Oppelia, Peltoceras, and Aspidoceras, and coral reefs have great extent. The north Russian or Boreal province has in its Jurassic rocks no species of Lytoceras, Phylloceras, and Haploceras, and no coral reefs, while those of Cardioceras and Aucella are widely distributed. On the other hand, the flora of the earliest part of the following Cretaceous period in Greenland included an abundance of Cycads. Although the cold of the Atlantic and Pacific barriers of North America was manifestly of little severity, it was enough for wide results in the geographical distribution of species. The Mexican Gulf was a source of warm waters for southern and interior North America, while at the same time the Arctic seas may have sent down polar currents over its northwestern interior during the Triassic period. The effects of the cold northwesterly currents of the Pacific border are plainly seen in the many species peculiar to that coast, and prominently in the Aucellae, which are related to the Siberian species. BIOLOGICAL CHANGES AND PROGRESS. Some of the Successional Lines. It is noteworthy that the new types of the Jura-Trias did not appear at equable intervals successively along the era. They were rather evolvings in its commencing part, the Triassic, the opening period of Mesozoic time. The Triassic period is thus, after the Cambrian, which opened the Paleozoic, the most eventful in the earth's biological history ; that is, the most pro- ductive of great branchings in the higher departments of the Animal Kingdom the type of Mammals, that probably of Birds, and those of each of the grand divisions of Eeptiles excepting such as had already appeared in the Permian. This is true also of the modern, or nearly modern, style of Orthopters, Neuropters, and Coleopters among Insects, as illustrated by Scudder ; and the Lias completed the display of the system of Insects by the introduction of the Dipters or Flies, and of Hymenopters as represented by Ants and other families. It is to be admitted, however, that part of the developments indicated by the relics in Triassic beds may date from the Permian. The physical change of a purified atmosphere prepared the way for terrestrial life ; and the preparation was essentially complete before the close of the Permian. This crowding together of the origins of so many types in connection with the barrenness of most Triassic regions makes it doubtful whether facts illustrating the precursor lines will ever be fully made out. As regards the precursors of Mammals, their closer relation to Amphib- ians than to Reptiles is proved, as Huxley first pointed out, by the fact that Amphibians and Mammals have two occipital condyles, and Reptiles and Birds but one ; and hence their derivation was almost certainly from some Amphibian type, and not from a Reptilian. The Monotremes (of which but MESOZOIC TIME TRIASSIC AND JURASSIC. 795 three species exist, one of Ornithorhynchus and two of Echidna) are the lowest of Mammals, and have many Amphibian and Eeptilian characters in their skeleton, besides that striking one of bearing eggs, like Reptiles and Birds. They are called Prototheria in some zoological systems; and this they undoubtedly are in type, though the Duck-like bill and webbed foot of the Ornithorhynchus are unquestionably degenerate characteristics ; for the earliest species had almost certainly a full set of teeth. That they were first in origin, however, is far from proved. Among Reptiles, the Permian type represented by the genus Palceohat- teria, with the associated Hhynchocephalia, as explained on page 707, is the most generalized or comprehensive of the class. Besides its Amphibian rela- tions on one side and its Reptilian on the other, it has, as Baur explains, characteristics also of Birds and Mammals. This author regards the type as the precursor type of the class of Reptiles and also of the class of Birds. It is like Mammals, he states, and unlike all other Reptiles, except the Rhyn- chocephs, in having the foramen of the distal end of the humerus on the inner side of the epicondyle ; in other Reptiles it is on the outer side or is absent ; and it is absent from all Amphibians and Birds. It is probable, therefore, that, nearly as Baur concludes, the line from the Amphibians which gave off a Rhynchocephalian branch, later gave off a Mammalian. The relation of Birds to the Dinosaurs in pelvis and hind limbs, especially to the Carnivorous kinds, was pointed out by Huxley ; and it is supposed that the two types may have originated from a common type in either the Triassic or Permian period. The Jurassic bird, Archaeopteryx, which is so remarkably Reptilian, has the long limbs, and but little else, of a Dinosaur ; and this feature in the hind limbs of both is partly a consequence of an elongation of the metatarsals. The cranium and the sternum are Bird-like, but not so the fore limbs, pelvis, and some other parts. The Berlin specimen was first described as a Reptile by Carl Vogt. The relations of Birds to Dinosaurs in the structure of the skeleton are largely a consequence of the demands made by the animal on its hind limbs ; and the unlike demands on the fore limbs are the source of divergences. General Changes Attending Biological Progress. 1. Reduction in multiplicate numbers. The reduction in number of pos- terior vertebrae when the Fish type passed to that of the Amphibian has been noticed on page 726. Their absence from the upper lobe of the tail in most Triassic Ganoids, rendering the Fish homocercal in place of heterocercal, is a change in the same direction, like that which takes place when the Tadpole becomes a Frog, or the young of a Ganoid or other Fish loses a caudal lobe, or some caudal vertebrae, when becoming adult. The long vertebrated tail of the Jurassic Bird was a related multiplicate feature, which disappeared early in Cretaceous time, if not before it. The reduction of the number of parts in the limbs of Fishes before the close of the Paleozoic to the typical number of five for the digits in 796 HISTORICAL GEOLOGY. Amphibians, and to typical numbers and arrangement in the bones of the leg, has been stated on page 726. Once reached, these numbers remain the normal or typical numbers for Reptiles, Birds, and Mammals. The typical number of cervical vertebrae, seven, sometimes occurs in Reptiles ; but varia- tion from this number is not in them a character of generic importance. Under Mammals, the differentiation of the teeth in all typical species, into incisors, canines, and molars, exists, commencing with Triassic Marsupials ; but the number of teeth continues to be multiplicate through the Jurassic, the typical Mammalian number, 44, being usually exceeded, and sometimes by 24. The number seven became the fixed or normal number of cervical vertebrae, first, among Vertebrates, in Mammals. It is a character of all existing Marsupials, and probably was of those of the early Mesozoic, a doubt remaining because no skeleton of an ancient species has yet been found. Exceptions to normal numbers, after they were once attained, have pro- ceeded from Specializations in the course of upward as well as downward progress ; but the larger part occur among degenerate forms, and in these, as the examples mentioned show, the divergence is often very great. 2. Location of the function of locomotion. As remarked on page 726, the typical Amphibian, on becoming adult, passes from the stage of caudal or urosthenic locomotion, to locomotion by limbs, or podostlienic. The latter is the typical condition in Reptiles, Birds, and Mammals. But groups under each differ as to the pair of limbs which bears the chief part of the work. The Triassic and Jurassic periods were distinguished eminently by hind-limb location of force and locomotion. It was the era of very small brains, and of great development of the posterior extremities the era of Merosthenic Vertebrates, as the Devonian and Carboniferous eras were of Urosthenic Vertebrates. The prominent feature of all Dinosaurs is their enormous hinder parts. Moreover, as has been mentioned, many of the species, the gigantic Stegosaurs preeminently, have a provision for this arrangement of the forces of the Reptile, as Marsh first brought out, in the great nervous mass of the sacrum. The Amphibians also were strongest in the hind limbs, as is indicated by the remains of the Labyrinthodonts. The wings of the Jurassic Bird of Solen- hofen prove that they were poor flyers, and consequently that their legs or hind limbs were their chief locomotive organs. Moreover, in this merosthenic era, the Mammals probably had the hind limbs much the stronger of the two pairs, as is true of modern Marsupials. The species of Reptiles that were distinctively strong in the fore limbs, or prosthenic, are the Pterosaurs ; and among these, the Pterodactyls, having the head large, the posterior feet small, and the tail short, with the brain and sternum Bird-like, appear to have taken the lead. Seeley has placed them in an independent group separate from Reptiles. The absence of scales from the body, and the light bones, with air cavities and pneumatic foramina, still further ally them to Birds, and separate them from other Reptiles. It MESOZOIC TIME TRIASSIC AND JURASSIC. 797 is probable, therefore, that this highly specialized type ranked above all other Reptilian types of. the Jurassic. 3. Degeneration. Progress in a type from toothed jaws to toothless must be viewed as a decline, although there may be true progress in other respects. Among the Rhynchocephalians which, in the Permian genus Palwohatteria, have numerous formidable teeth occur later species having a horn-covered extremity of the jaws like the beak of a turtle. Again, the Dinosaurians vary from many-toothed, tiger-mouthed species, to those with few teeth. The Plesiosaurians are supposed to be degenerate land Eeptiles, whose limbs, even in the Triassic, had become paddles, with fingers multiplicate in number of phalanges; and the Ichthyosaurs, species of some other Reptilian type, carried downward to a still lower urosthenic stage, in which the pelvic girdle had become nearly obsolete, and the fingers sometimes excessive in number, as well as multiplicate in segments. Turtles are other degenerate forms of the Triassic as well as of the Jurassic period. Such facts make it manifest that through geological time progress in the Vertebrate type, as in the Invertebrate, was downward as well as upward j that degeneration, while it may make obsolete, may also return a species to a low multiplicate condition, in which the multiplicate characteristic extends to the number of vertebrae, to the teeth, to the fingers, to the number of finger bones, and to other parts of the structure. It is atavism under some physiological law deeper than atavism, bringing back characters, not of the earlier Reptiles, but of the earliest Vertebrates, the Fishes, yet not without any loss of the fundamental characteristics of Reptiles. Considering the very long time that Fishes were in the seas before the rise in grade to the terrestrial type of the Amphibian, and the relatively short time for the much greater rise from the Amphibian to the Reptile, Bird, and Mammal, there is no reason to believe that any of the upward successional lines passed through the water. Through the water, for terrestrial Verte- brates, as many examples show, was a quick way down in grade, not a possible way up. 4. A fragment of the Triassic world. Australia is often spoken of as a Triassic continent. As the world in Triassic time had only Marsupials and Monotremes for its Mammals, so Australia has now, man's encroach- ments excluded, Marsupials and Monotremes for its only Mammals. The existence there of a species of Bat, and of some Mice and Rats, is hardly an exception to be considered. But although thus restricted in its modern fauna, its Mammals are not of few kinds ; for, as Wallace states, " some are carnivorous, some herbivorous ; some arboreal, others terrestrial ; there are insect eaters, fruit eaters, honey eaters, leaf or grass feeders ; some resemble wolves, others marmots, weasels, squirrels, flying squirrels, dormice, or jerboas." Moreover, one of the last four species of Cestraciont Sharks, a tribe of Mesozoic and Paleozoic affinities, the Cestracion Philippi, or Port Jackson Shark, lives in Australian seas ; and one of the last three species of the Dipnoans, the Ceratodus, Carboniferous and Triassic in type, inhabits its 798 HISTORICAL GEOLOGY. interior waters. Besides, the surface rocks of the continent are to a large extent Permian, Triassic, or Jurassic. Marsupials and Monotremes formerly had a wide range over the globe. A large Echidna, or Monotreme Porcupine, was among the species of England in the Middle Quaternary ; and Marsupials, among the Mammals of Europe and America in the Tertiary ; but at the present time the few of South and North America are all that exist out of Australia. It cannot be affirmed that Triassic Australia was the source of all the Marsupials of the world ; but there is little doubt that its only Triassic Mammals were Marsupials and Monotremes. It has already been explained that New Guinea and New Zealand show by their faunas that they were once parts of a great Australasian continent, New Guinea having its Marsupials, and New Zealand the only surviving species of the Permian and Triassic tribe of Rhynchocephalians, in a species of the genus Hatteria. The possible extension of the continent southward, and its union for a time with an Antarctic continent, are considered on page 737. DISTURBANCES AND UPTURNINGS DURING, OR AT THE CLOSE OF, THE TRIASSIC AND JURASSIC PERIODS. Triassic of the Atlantic border. The Triassic areas of the Atlantic border bear evidence of a general upturning, in which the beds were, with small exceptions, raised not into flexures, but into monoclines. The effects of the movements have been briefly stated on page 357, under the subject of mountain-making. Additional facts and illustrations, respecting the disturbed areas, and the orographic results and methods, are here presented. The close parallelism between the Triassic areas and the Appalachian chain is one of the great facts to be here noted. It is well seen on the map, page 412, and for Pennsylvania on that of page 730. The general parallel- ism between the strike of the upturned beds and the same course that is, the trend of the areas is another important fact. The two are satisfactory evidence that the agency concerned over the Atlantic border was the same for Jurassic time, as for the epoch when the Appalachians were made ; and, it may be added, for all epochs of Eastern Border mountain-making. In the Connecticut valley area there was an eastward dip also in the fracture planes, and a westward upthrust along these planes ; and this also was a feature of the Appalachian upturning. These facts imply the action of lateral pressure from the eastward, or the direction of the ocean. In the Palisade area passing from New York through New Jersey and Pennsylvania into Virginia, and in the western areas of Virginia and North Carolina, the results of the upturning are in general the reverse of those in the Connecticut valley and in eastern North Carolina. The beds of sandstone and the great fracture-planes, for the most part, dip westward or northwest- ward, and the upthrust along the fracture-planes was southeastward. MESOZOIC TIME TRIASSIC AND JURASSIC. 799 In Connecticut, the sandstone beds almost invariably dip eastward. In Virginia, in the Richmond area, which is one of the easternmost, the beds have a synclinal structure, the rocks on the east side dipping northwestward, and those on the west side, southeastward (Fontaine). In the eastern Deep River area of North Carolina the dip averages 20 southeastward, but varies from 10 to 35 (Fontaine). Notwithstanding the diversity between the orographic features of the more western and the eastern belts, the intimate relation to the Appalachian system as regards method of upturning of the former as well as of the latter cannot be questioned. The opposition of direction in dip is connected with opposition in all other structural features in the two ranges of belts, and eminently so in the topography. The opposition in dip between the Connecticut valley and the Palisade area has been explained by supposing that the sandstone was made in waters that spread over the intervening region, and that an actual anticline was produced by an uplift. But only marine waters could have covered the wide region after great subsidences ; and to this idea, all the facts as to the fresh- water origin of the beds by fluvial, lacustrine, or estuary agency are opposed. Moreover, the Connecticut valley area is wholly in latitudes more northern than the Palisade. This reversed condition, so marked in the results over the two areas, simply implies reverse action in the forces concerned. In the Palisade region, accordingly, the lateral pressure was from the westward; thus came the reversed dip and reversed fault -planes and faulting. On this view of the action along the two belts, that is, the lateral thrust from the eastward for the eastern, and from the westward for the western, the pressure was such as would tend to make, or actually did make, a geanticline between two extended lines, an eastern and a western. But upturnings of beds took place only where there had been geosynclines of deposition, that is, in the Triassic areas. The effective upturning force acted alike from opposite directions, the eastern, or oceanward, and the western, or landward ; while in the Appalach- ians its action was from the eastward chiefly ; but, still, like the Appalachian Range as a whole, each of the several areas is inequilateral in orogenic struc- ture. The Connecticut valley area tapers out, both as to width and depth of deposits, at New Haven Bay on the Sound. There is no trace of the trough over Long Island. It is possible that in the direction of this eastern Triassic line a sandstone area existed over the shallow-water border of the Atlantic, south of Long Island and east of New Jersey; but no proof of this has been observed. In the Richmond area of eastern Virginia, however, and in the Deep River area of North Carolina, as the dip of the beds of each proves, the true continuation is found, for these areas have the same position relatively to the western areas of those states, as the Connecticut valley area has to the Palisade area. The map on page 412 illustrates the fact, not only that these areas mark out the position of the eastern side of the series of Triassic belts, but also that it is parallel to its axial line. 800 HISTORICAL GEOLOGY. In the progress of the upturning the sandstone was variously fractured and faulted ; and the masses into which it was thus divided were in part forced over one another, and up whatever surfaces lay beyond, and thus the monoclinal structure was produced. The abraded surfaces of the beds, extensively exhibited in some regions, indicate that there was a vast amount of intestinal movement as well as ordinary faulting. The sandstone should therefore have acquired its greatest thickness, from piling on itself, on the side of the area in the direction of the movement ; that is, on the west side in the Connecticut valley, and on the east, in the Palisade belt. Moreover, the confining slope of the trough on this side would have been an obstruc- tion that would have there increased the fracturing and the amount of piling. The lateral thrust would have narrowed the belt of deposits of each geosyncline. The amount of narrowing, taking the mean dip of the beds at 15, and supposing no modifying conditions, would have been about 100 feet for every 3000 feet of width. But the piling of the beds referred to above, and the shoving of the beds beyond the limit of the original area or trough, are modifying conditions that cannot be estimated. The shallow mass of deposits in each geosyncline had a temperature at bottom possibly of 200 F. or 300 F. ; for, if 10,000 feet thick, the present rate of increase in temperature downward would make the maximum only 200 F. This temperature was sufficient only for a partial consolidation of the beds through any siliceous waters that might have been made, and for the reddening of them by the oxidation of any iron present. The movements from lateral pressure against the trough in the earth's crust, in which the beds lay, might have produced their results by molecular transfer in the mass of the crust. But the facts point unquestionably to great and deep fractures. The directions of such fracture-planes would have been deter, mined partly by the positions of the weaker planes in the rocks beneath. Such weak planes may be due to kinds of rocks; to the foliation or bedding of the rocks ; to earlier fault-planes ; or to preexisting mountain features of the Atlantic border. But their actual positions are not often determinable except so far as they may be inferred from the lines of eruptive rocks. Igneous eruptions over the Triassic areas. The general features of the outcrops of trap over the areas are well displayed in the Connecticut valley, an excellent map of which for the state of Connecticut is contained in J. G. Percival's Geological Report (1842) ; and for the Massachusetts portion, by B. K. Emerson, in the Bulletin of the Geological Society of America for 1891. The accompanying map, Fig. 1346, which is part of Percival's, embraces the southern three fifths of the whole area in Connecticut, or the part from the Sound to the latitude of Hartford. Its length is 37 miles, or about one third of that of the whole valley. On the map the dotted lines nn, mm mark the outlines of the Triassic area ; outside, both to the east and west, the rocks are crystalline rocks. The heavy black lines rep- resent the outcrops of trap. Commencing at the south, the abbreviations used on it are as follows : N H, New Haven ; pp, 6&, dikes of trap outside of the area, on the west ; and MESOZOIC TIME TRIASSIC AND JURASSIC. 1346. 801 Map of part of the Triassic area of central Connecticut. J. G. PercivaL DANA'S MANUAL 51 802 HISTORICAL GEOLOGY. ee, another on the east ; S, Saltonstall Ridge, called Pond Ridge by Percival ; T T, Totoket Ridge ; C, Mount Carmel ; M, Meriden ; Mt, Middletown ; Pd, Portland and Portland sandstone quarries ; H, Hartford. The scale of the map is ^ of an inch to 5 miles. The many interruptions in the lines of trap on Percival' s map are generally due to intervals of sandstone, and the smaller of them may often have resulted from falls of the sandstone walls of oblique fissures, as explained on page 298. But in some cases they are breaks in the outcrop of trap in which no sandstone was in view, and where further in- vestigation may prove the line to be continuous. One such case exists in the termination of West Rock, and another in the south side of the summit of Mount Carmel ; and changes have been made correspondingly in Percival's map. One other change made, in order to represent the results of later observation, is the continuation of the dike bb to and across West Rock. Some of the general facts of importance illustrated on the map are the following : 1. The outcrops are most numerous in this southern portion of the area. To the north of the region here mapped, there are only continuations -of the three western lines to Mount Tom and Mount Holyoke in Massachusetts, and an isolated line farther north which passes near Greenfield. 2. The outcrops of trap are not wholly confined to the Triassic area. Two lines of dikes exist on the west side (pp, bb, on the map) ; they con- tinue southwestward to the Sound. In one of them, the trap is sparsely porphyritic with crystals of anorthite. There are also two long dikes on the east : one, commencing in ee, to the eastward of New Haven, not a mile distant from the area, has a course nearly parallel to its eastern outline for 10 miles, but afterward diverges from it ; the other commencing nearly east of Hartford, just outside of the area, is parallel to the area for the same distance. Both were traced by Percival to the Massachusetts line. The convergence of the dike ee, southwestward toward New Haven Bay, and that of the other lines of trap in the Triassic area, are part of the evidence that the estuary or trough terminated at this place. 3. The trap (doleryte or diabase) is essentially the same rock in all the belts, and through all the Triassic areas. It is sparingly chrysolitic, according to Iddings, in Orange, N. J., and rarely so in other places. The chief variation is a result of alteration by means of water imbibed as vapor, when, it is believed, the rock was on its way through the sandstone to the surface. The rocks are sometimes unaltered on one side of a belt, and much altered along its middle or on the other side. Dikes intersecting the outside crystalline rocks are wholly free from the alteration, showing that the moisture was not from the same source as the trap, but more superficial. The altered hydrated trap has little luster ; is often amygdaloidal within 50 feet or so of the surface ; and decomposes rapidly, and often to a depth of several yards, so that a small dike between layers of sandstone is sometimes found wholly changed to a brownish yellow earth, and looks like a bed of tufa. Fot remarks on amygdaloids, see pages 78, 336. Along some of the fissures there were carried up with the trap ores of copper, and thus copper veins were made in the trap and in the sandstone of the vicinity (page 338). MESOZOIC TIME TRIASSIC AND JURASSIC. 803 4. The lines of trap on the map are usually curved, with the convexities to the west ; or they consist of a series of similar curves. Some are bow- shaped with hooked ends. Saltonstall Ridge at S, on the east side of Salton- stall Lake, near the Sound, is a marked example of the bow-shaped outcrop. So also is the narrow line just east of it, and another broader and larger line to the northeast, the Totoket Eidge, T T. The Mount Tom Eidge has an eastward bend, hook-like, at its southern end, in the Meriden region, and another long one at its northern end, constituting Mount Holyoke. The distance between the two hooked ends is over 50 miles, so that it is a very long bow. West Eock Eidge has a hook at its southern extremity, and a series of curves in its course to the north ; but it terminates northward near where the Mount Tom Eidge ends, as if a sequel to the latter in formation. These features are so general that they seem to indicate some compre- hensive method of origin. 5. The belts are for the most part approximately parallel to the axial line of the area, or nearly north-by-east in course. But there are many, exceptions, especially in the southern part of the area. The large north-and-south outcropping belts of trap usually have bold features over the landscapes. This prominence is owing to denudation since the time of the eruption of the trap, for originally the trap was probably all under the cover of the sandstone. The hard igneous rock generally makes the summits of ridges. The slope of the ridge in the direction of the. dip of the sandstone (eastward in the Connecticut valley) is usually gradual, and along it the trap disappears beneath overlying sandstone ; but in the opposite direction, the ridge has a bold front of columnar trap resting on the sand- stone. At the contact with the trap, in a north-and-south ridge, the sandstone appears to be horizontal, because its dip is not northward or southward, but eastward. Only in a transverse section of such a ridge should the underlying sandstone show its true inclined position. These facts are illustrated in the figures on page 302. The general features of the bold trap front are better shown in the following view of West Eock ; but the part exposed to view is an east-and-west section, so that here the dip of the sandstone is exhibited. Below the bold columnar front of such ridges there is usually a talus of broken blocks of trap ; the removal of this talus (for road making) has exposed the sandstone to view. (The nearly horizontal line below the out- cropping sandstone is the course of a road.) The Palisades along the Hudson are another good example of a trap ridge. The bold front of the Palisades faces eastward, the dip of the sandstone being to the westward ; and as the ridge has a northward course, the underlying sandstone, which makes about half the height above the river's level, presents a nearly horizontal line beneath the trap. The east-and-west outcrops of trap are generally lines of simple trap dikes; that is, of trap within the fissure up which it flowed. On the contrary, each north-and-south outcrop in almost all cases is that of an outflow of trap from a supply fissure, which is situated somewhere to the eastward. Examples 804 HISTORICAL GEOLOGY. of large dikes, 180 to 300 feet wide, are shown in Pine Rock and Mill Bock, on the map on page 299. Smaller dikes are very common in many localities. The West Rock Ridge, Mount Tom Ridge, and Saltonstall Ridge afford examples of outflow masses or sheets. With regard to the West Rock trap- mass it is proved, on page 302, that it is a laccolith ; that the eruptive rock, coming up from below, was forced into a space opened by itself between layers of the sandstone, and there it accumulated under the weight of the superincumbent sandstone, probably one or more thousands of feet thick. It is also shown that the upturned sandstone underneath the outflow, Fig. 1347, was profoundly abraded by the forced movement, over it, of the melted 1347. View of the south front of West Eock, near New Haven, Conn., showing the columnar trap and the sandstone underneath it. rock, and thereby reduced to a nearly horizontal surface. No earth or stones intervene between the trap and sandstone in the section exhibited, showing that the material removed by abrasion was pushed on and lodged elsewhere ; and also proving that the flow was not surficial, inasmuch as all surface earth or debris is absent. It has been shown, besides, that East Rock, near New Haven, is laccolithic ; and so also the trap belt next west of the Salton- stall Ridge, and the second trap belt east of the same, as described by E. 0. Hovey. In addition, the trap rests, in each case, on upturned sandstone, proving that the upturning was a previous event for the region. It follows, therefore, that the trap of the intervening Saltonstall Ridge must be similar in mode of origin and time of eruption. MESOZOIC TIME TRIASSIC AND JURASSIC. 805 1348. Ts efeet. Trap bluff at Greenfield, Mass., with breccia of sandstone blocks (the part Tt cemented by trap, and Ts by sandstone) lying between it and the sandstone S. B. K. Emerson, '92. While the West Rock section, Fig. 1347, indicates, not only a great amount of abrasion, but also a shoving forward of the abraded material beyond or west of the place in view, that of the second trap belt east of the Saltonstall Ridge has the abraded material resting on the underlying sandstone in the form of rounded and angular stones of the trap and sandstone ; the accumulation was evidently made, as Hovey states, by the friction between the liquid and solid rock. B. K. Emerson reports that the trap sheet of northern Greenfield, Mass., where the bluff or trap faces westward (the dip being east- ward), as shown in Fig. 1348, rests on a bed of coarse sandstone breccia, 12 to 16 feet thick, the upper part of which (Tt) is cemented by trap, which extends from above between the blocks, and the lower part, 6 or 8 feet thick (Ts), by red sand, which is continu- ous with the underlying sandstone. More- over, the bed of trap breccia rests on unbaked sandstone. At a locality in the Mount Tom Eidge, in the town of Holyoke, the base of the trap, according to Emerson, is " kneaded full of dove-colored limestone," looking u as if the limestone and trap had been plastic at the same time " ; and at one place, where the trap is about 300 feet thick, its " upper surface is filled in the same way with the same lime- stone to a depth of 8 or 10 feet." The limestone had been torn off from a layer not visible in the section ; for, as he says, only sandstone is there in view, or was found in a boring carried down 3500 feet. The large north-and-south belts of trap often have an attendant belt on the east or west side, or on both, which is generally made of hydrous and amygdaloidal trap, even when the trap of the large belt is of the normal anhydrous kind. Percival draws special attention to this feature. The Mount Tom Ridge is thus attended, as the map on page 801 shows, from the Meriden region northward ; the line, which is low from denudation, is on the western side through the southern part of the Mount Tom Ridge, and on the eastern side for the more northern part. Saltonstall Ridge has a similar parallel belt to the east, and another to the west of it, only a few hundred yards distant, and each is perhaps of like relations to the "attendant" dike of the Mount Tom Ridge. The time of the eruptions and their relation to the upturning of the sand- stone. The evidence is complete that eruptions of trap preceded, as held by Emerson and Davis, the deposition of part of the sandstone. The sand- stone of East Haven, east of Saltonstall Ridge, contains stones of trap at many places, as described by E. O. Hovey, while none are known to occur 806 HISTORICAL GEOLOGY. over the region west of the ridge. It follows therefore that the eruptive work began before the close of the period of the sandstone formation. But it appears to be also true that it characterized the closing part of the period. The facts from West Rock, and others of similar import from East Haven, where the trap rests on upturned sandstone, are evidence that so far as these regions are concerned, the upturning preceded the eruptions. This conclusion involves the Saltonstall region ; and if this, so also the Totoket Ridge and others to the north, since all are closely alike, and in close con- junction. Moreover, a laccolithic origin may be inferred not only for East and West Rock, but for all such cases. With regard to the Mount Tom Ridge, direct evidence of age of eruption is wanting ; for no east-and-west sections have been reported. But a lacco- lithic origin and the abrasion of the underlying sandstone are indicated by the occurrence of breccia beneath the trap, and especially by the limestone chips in the lower part of the mass of the trap, and also over its upper surface, as described by Emerson. A bed of limestone was evidently divided by the advancing tongue of melted trap, part being left below, and the rest above. As Emerson observes, the facts prove that the heavy trap flowed over the sandstone, abrading and tearing it. But they prove also that the flow was not surficial, but laccolithic ; for in the case of an advancing surficial stream the lava, being retarded by friction at bottom, has a downward flow at the front, and hence could not bear to its upper surface material met with along its track. A laccolithic origin for the Mount Tom Ridge explains also the existence of the attendant dike parallel with its southern, western, or eastern side, and for similar cases elsewhere. For whenever, in the forced flow of lava from the supply fissure to make the laccolith, the force could not so easily con- tribute to the laccolithic mass (owing to the weight it had acquired by accumulation and that of the overlying sandstone, and to resistance from other sources) as make a fracture either side for a new place of escape, the latter event would take place. A dike of five inches, which is visible under the trap mass in the south front of West Rock, and which is both amygda- loidal and chrysolitic, is probably an example of this mode of origin. This evidence of a laccolithic origin brings the north-and-south trap belts into the same category, as to method and time of origin, with West Rock and East Rock. After or during the upturning of the sandstone appears, therefore, to be the time of origin of the larger part of the eruptions. The hypothesis has been brought forward by W. M. Davis (U. S. G-. 8. Sep., vol. vii., and elsewhere), that the larger part of the trap was erupted in the early part of the Triassic period long before the upturning; that in the case of the Connecticut valley area, the trap was poured out surficially from fissures along the eastern margin of the area, and thence flowed westward across it over the underlying sandstone ; that after more sandstone had been deposited a second and larger surficial flow took place ; then after more deposition of sand-beds a third smaller flow ; and that this interstratified sandstone and trap were covered by other horizontal deposits of sandstone of great thickness ; that, MESOZ01C TIME TRIASSIC AND JURASSIC. 807 finally, at the time of upturning, the trap and sandstone, thus interstratified, were forced up into monoclines, which by denudation became the existing trap ridges. According to the views already presented, (1) the trap mass in the trap ridges may be conformable, or not, to the associated sandstone ; and (2) the supply fissure was near the eastern base of the ridges, or not far distant. These conditions are illustrated in Figs. 275, 276, on page 302. In the views of W. M. Davis, on the contrary, (1) the trap mass of the ridges is conformable with the sandstone and with its other trap sheets ; and (2) it extends to the east and west of the ridges as a conformable sheet in the sandstone forma- tion, and should be found there by boring if not exposed at surface. It is favorable to this hypothesis that the sandstone is admitted to be in monoclines ; that the trap ridges look like monoclines, the trap and sandstone so far as exposed to view being eastward in dip ; that the greater trap belt and the smaller attendant belt on the east and west have the positions in the external view that correspond to layers in a monocline ; that in some regions the beds of the sandstone formation underneath the columnar trap in the front of trap ridges have a like order of succession. But it is unfavorable to it that the hooked or bow-like shapes among the ridges are not such as are characteristic of monoclinal regions ; that the varying dip of the sandstone within the bow it being nearly at right angles to the direction of its sides and ends is an exceptional feature for monoclines, and an actual feature of those trap ridges which are admitted by all to be eruptive. It is also unfavorable that no outcrops of either of the three conformable sheets of trap have been observed along the eastern margin of the area ; that no sections of the sandstone formation occur anywhere in the part of the area east of the Connecticut River, which exhibit the conformability of the trap sheets with one another or with the sandstone, or that show any trap at all ; that no sections exhibiting conformability have been observed in any of the trap ridges themselves, and none over the part of the Triassic area west of these ridges. Thus positive evidence in favor of the hypothesis fails ; and there is the evidence against it that the Saltonstall region, instead of exemplifying it, as claimed by its author, is a region of eruptions after the upturning of the sandstone, and that the Mount Tom Ridge bears the strongest evidence of a laccolithic origin. The existence of buried volcanoes at Mount Carmel (740' high), 9 miles north of New Haven, has been announced. But there is no evidence of the "buried volcanoes" in sight : neither in lava streams, volcanic ashes, nor anything else. The rocks in view are the ordinary compact trap of the trap dikes of the region and the intersected granitic sandstone. Origin of the eruptions. Although the geosynclines or troughs in the earth's supercrust occupied by the deposits were comparatively shallow, none probably exceeding in depth 10,000 feet, the lateral thrust from the opposing directions produced, at intervals, fractures and movements, if not also crushings, at considerable depths for the whole length of the Eastern Continental border, from Nova Scotia to southern North Carolina. For, according to existing theory, the region of fusion was where the earth's interior temperature was so near the fusing point of the rock, that the heat from dynamical sources, added to the statical heat of the region, would produce fusion. The near uniformity in the kind of ejected rock, through all the Triassic areas, has been already mentioned as other evidence that the fissures descended below the supercrust to regions where basic Archsean-like rocks prevail. The ejection of rocks of the basaltic type alone may, however, be a consequence of the temperature not being high enough to melt the less fusible rocks containing oligoclase or orthoclase. 808 HISTORICAL GEOLOGY. It is a fact deserving especial note that although the subterranean fusion occurred at intervals for 1000 miles, the fissures by which ejections took place were almost wholly confined to the narrow areas of the Triassic geosynclines. The isolated Southbury area of Connecticut, a dozen miles west of that of the Connecticut valley, and only seven by two and one half miles in area, has its many trap dikes ; and none exist over the intervening region or to the north, west, or south of it. The isolation of the eruptions corresponds with that of the upturning. The areas of the geosynclines that is, of subsidence and deposition in some way localized the areas of fractures and fusion. There seems to be good reason, in the facts, for locating the chief of the fractures underneath the center or central line of each area and under that half of it which is nearest to the general axial line of the chain of areas, rather than underneath the outer margin of the other half, or in any part of this half ; that is, in the Connecticut valley area, as Percival's map illustrates, for locating it underneath its central line and the half to the westward, rather than underneath the eastern part. There are, however, two long dikes just east of this Triassic area, besides two others to the west of it. One of the southwestern of these out- side dikes, bb on the map, is proved, by its cutting through the West Rock trap, to have been of subsequent origin ; and this is probably true of all four. The four are alike, moreover, in having a mean course of N. 25-30 E., thus differing about 15 in easting from the average course of the trap belts in the Connecticut valley. Similar facts are afforded by the region of the Pali- sade Range. They accord with the idea that these outside dikes were erupted when the orogenic catastrophe was near its close, and the localizing geosynclinal conditions had lost part of their influence. Perhaps tension from a decline in the lateral thrust, or from a dissipation of the subterranean heat generated by the movement, led to these divergent lines of fracture and eruption. According to J. J. Stevenson, great displacements have been produced in the faulted Appalachian region of northwest Virginia at some time subsequent to the origin of the range; and it is probable that the epoch was coincident with that of the Triassic upturning. ( Am. Jour. Sc., xxxiii., 262, 1887.) Movements over the Eocky Mountain Region and the Pacific Border. Making of the Sierra Nevada. Along from Mexico northward, in the Rocky Mountain region, thick Triassic and Jurassic deposits were in progress, preparatory for future mountain-making ; but, in general, only oscillations, and some emergences in the general course of geosynclinal subsidence, have been reported. Over the summit region of the Rocky Mountains deposition was continued quietly, as a general thing, through another period, the Cretaceous, before any great disturbance took place. On the ground of the absence of Liassic beds over the region south of Wyoming, R. C. Hills has inferred that an emergence MESOZOIC TIME TRIASSIC AND JURASSIC. 809 there took place after the Triassic. In the Sierra Nevada an unconformity occurs, according to Diller, between the Lias and Upper Trias of the Taylor- ville region, but the succession of deposits shows that no emergence in that portion of the Sierra Nevada accompanied the disturbance. In the Island belt of British Columbia, along Vancouver and the Queen Charlotte Islands, an emergence occurred after the Triassic period; for no Jurassic beds exist between the Triassic formation of the region and the Cretaceous ; moreover, at some time between the Triassic period and the Cretaceous, according to G. M. Dawson, an extensive upturning of the Triassic beds took place; but whether at the close of the Triassic or of the Jurassic is left uncertain (1886, 1887). The dose of the Jurassic period was the time of the making of the Sierra Nevada Eange, as announced by J. D. Whitney in 1864 (Am. Jour. Sc., xxxviii., 1864; Rep. Geol., 1865), after the^ discovery of Triassic and Jurassic fossils in Plumas County, and of Jurassic in the Auriferous slates of Mariposa County and other regions. This conclusion has been questioned and the event referred to the Middle Cretaceous, on the ground chiefly of resemblance between the Aucellse of the Jurassic Sierra slates and those of the Lower Oetaceous ; but it has been fully confirmed by the study of the Mariposa and other fossils by Hyatt and others, and by the fact of the unconform- ability of the Lower Cretaceous with the rocks of the Sierra in many places west of the Sacramento River. It is also sustained by the fact of the conformability of the Lower and Upper Cretaceous, or the Shasta and Chico series, as observed by Diller; who has, moreover, traced the imconformability, not only along the west side of the Sacramento, from Pit River southward by Bedding, Horsetown, and Ono, into Tehama County, but also northward by Yreka and Ashland, far into Oregon. Moreover, other ranges to the west and north participated in the upturning; for the Coast Range and the Klamath Mountains were parts of the result, according to Diller and Fairbanks ; and it may be that still others in the Sierra line, to the north or south, were then formed. The black slates and siliceous rocks of the auriferous belt of the Sierra are associated with hydromica schist, hornblende schist, serpentine, crystal- line limestone, along with some sandstone, and with limestone which is semi-crystalline. From the Mariposa region northward they commonly have a dip eastward of 60 to 80 or 90. The relative positions of the rocks of the belt are finely exhibited on the colored geological maps of parts of the Sierra region published by the United States Geological Survey, prepared chiefly by Lindgren and Turner. They show by colors the positions of the areas of outcrop of the granite or dioryte, which makes the core of the Sierra, and also of the various eruptive rocks of the region as well as the belts which make up the Auriferous series. In the Taylorville region, Plumas County, the beds, ranging from Upper Jurassic to the Silurian, are partly in overthrust flexures, the thrust being to the eastward (landward) as described and figured by Diller (G. Soc. Am., 810 HISTORICAL GEOLOGY. 1892). It is probable that there were ranges of flexures and monoclinal shoves along the rest of the Sierra to the southward and great upthrust faults also in the Taylorville region. . The maximum thickness of the rock in the Taylorville region is 24,500 feet, of which 17,500 feet are Paleozoic and 7000 feet Mesozoic (Diller). The Sierra Nevada geosyncline of deposition, which began during or before Upper Silurian time, hence reached in this part a depth nearly of 25,000 feet ; this was the thickness of the pile of deposits that was upturned and flexed in the crisis of mountain-making at the close of the Jurassic. The heat generated by the movements was sufficient for the rather feeble meta- morphism which characterizes the rocks. Facts also appear to prove that the core of diorytic granite, which is the chief rock of the ridge to the south, was an Archaean ridge over and against which the thrust took place ; for the stratified rocks, where in contact with it, show in some places in their crystallization or metamorphism the effects of the friction. For an example of such effects, see page 534. This view of the Archaean age of the Sierra core of granite is presented by King in his 40th Parallel Keport, 1878. The Sierra Nevada, when first formed, probably had not half its present height. It has a later history of great geological interest. The formation of the gold-bearing veins of quartz in the Sierra rocks was a consequence of the upturning. The wrenching of the strata opened the leaves of the slates, and also made great intersecting fissures. The opened spaces and fissures became filled with silica (quartz) which the heated mois- ture took into solution, and also with such ores as the vapors found in the beds. Some of the auriferous quartz veins have a width of 10 to 40 feet. As the modern Sierra gravels contain gold from the rocks which make the modern Sierra, so the more ancient rocks, of Jurassic and earlier origin, must have held gold from the earlier crystalline rocks of the Sierra; and this gold, with ores of lead, copper, and other metals, the hot vapors gathered into the- fissures. It was not the work of superficial waters ; for the veins now visible on the Mariposa estate and elsewhere are, owing to denudation, thousands of feet below the original surface ; but there is no doubt that superficial waters took part in the work. The metamorphic effects include many rocks in the Coast Range, besides prevailing kinds above mentioned, as stated on page 318 ;, and through Becker's studies the region has become an especially instructive one on the general subject of metamorphism. The "granite core" of the Sierra constitutes the culminating points in the southern portion of the range among them Mount Whitney, which has a height of 14,898 feet above sea level; and it is the rock of the famous Yosemite Valley. Whitney states that the slates near the granite are harder than at a distance from it, and contain horn- blende ; that veins of granite extend into the altered schists. And Diller describes contact phenomena observed by him in the Taylorville region. Moreover, some of the auriferous quartz veins extend into the granite. Evidence of this kind led Whitney, in his California Report, to present the view of the post-Jurassic age of the granite ; and several recent investigators of the region hold the same opinion. But intrusions of MESOZOIC TIME TRIASSIC AND JURASSIC. 811 dioryte in dikes would be a natural result of friction along fault-planes cutting through such an underlying crystalline mass. The extrusion of igneous rocks accompanying mountain-making has been a common fact over the summit region of the Rocky Mountains ; an example occurs in the Wasatch, which has, like the Sierra, a "granite 1 * core. Had the granitoid mass been a result of deep-seated eruption at the time of the upturning, or at any later date, or earlier, it would have come to the surface in great fissures ; for fissures, as the result of fractures, give exit to the confined liquid rock of the earth's depths. Moreover, liquid dioryte is identical with andesyte lava, and liquid granite with rhyolyte ; and if ejected at the time supposed, it should show evidence of the chilling effect of the relatively cold Sierra rocks along their contacts with them. Instead of this, the rock of the core is well crystallized to its surface, and has a coarseness of crystalline texture which indicates extremely slow cooling. Neither is the existence of auriferous quartz veins in the granite positive evidence of its recent origin ; for the granite of Pike's Peak, according to W. Cross, contains sandstone dikes (Feb., 1894). Further, if the ridges of crystalline rock in California and to the north are all eruptive and of late Mesozoic age, as is urged, and the emergence at the close of the Triassic is the earliest of much importance, there is no sufficient source for the sediments of which the successive sedimentary rocks were made. They could not have come from the eastward ; for the oceanic currents of the Pacific border are now, and must have been in early time, from the northwest ; and besides, the ridges of the Pacific border are north or northwest in course. Moreover, oceanic currents are relatively feeble transporters, and find their material for rock making near at hand. Such a mass of crystalline rock having irregular or indefinite outline has received the name of bathylite. (Bathylith would be a better name, as it is here used for a mass, not a kind, of rock. ) It has one mode of origin that is consistent with indefiniteness of outline. When a pile of deposits, 30,000 feet or more in depth, has beds in its lower portion that admit of fusion under the action of the heat producing metamorphism, the melted material would make a mass of indefinite outline. The fusion, under the same circumstances, of the rocks immediately below the pile, might add to the melted mass or be its chief source. Here is fusion unbounded by the walls of a fissure. This was common, as has been else- where remarked, in Archaean time. There is no sufficient evidence that it occurred during the Sierra upturning at the close of the Jurassic, or in any other part of Mesozoic time. The pre-Cretaceous age of the metamorphic rocks of the Coast Eange has been urged by Fairbanks (1892). This view is held also to some extent by Turner and Diller ; and the latter states that the Coast Kange was up- heaved with the Sierra Nevada at the close of the Jurassic. This conclusion is drawn from the fact that the Cretaceous thins out, both to the eastward and westward of the Sacramento valley, and that the later beds have their greatest extension in these directions. The Cascade Eange appears, from its position, to be part of the Sierra system. Becker reports that the same class of metamorphic rocks characterizes the portion of it in Oregon where not buried beneath later volcanic ejections. The Blue Mountains of Oregon also have their Jurassic rocks, and were probably among the results of the post- Jurassic upturning. In the Plateau Belt, or that of the Great Basin, near Carson Lake, the West-Humboldt range, according to King, was made at this time. It includes several ridges between 1171 W. and 119 W. ; and the thickness of the 812 HISTORICAL GEOLOGY. Triassic and Jurassic rocks in the West-Humboldt and Pah-Ute ridges is stated to be 20,000 feet or more. The Sierra and Wasatch ranges have reverse positions with reference to the Great Basin. Each stands with its steepest side and its high shoulders toward the basin ; and in each, if the views above stated with reference to the Sierra Nevada are correct, this bold side is made up in part of an Archaean range, which was really the protaxis and backbone of the mountains. In the Vancouver and "Coast Kanges" of British Columbia the underlying rocks -are gray granitoid kinds, containing much hornblende. The granite of the latter is associated with mica schist and hornblende schist. In the former, according to Dawson, the granite underneath the stratified beds of the Vancouver Island series is charged with innumerable darker fragments from these overlying rocks for a distance inward from the surface of the granite in some places of a few hundred feet to half a mile. How such a penetration of fragments from the non-metamorphic beds could have been produced, Whether the granite were of later eruptive origin, or of earlier production, is unexplained. If the granite were metamorphic eruptive, and thereby simultaneous with the upturning in its eruption, the Vancouver strata would have been distinctly metamorphic. In Europe, through the Triassic and Jurassic periods, great preparations in rock deposition were in progress over deepening troughs, for the making of the Alps, Pyrenees, Carpathians, Apennines ; but the crisis in all these cases was delayed until the Tertiary. 2. CRETACEOUS PERIOD. The Cretaceous period, the closing part of the "Age of Reptiles," is remarkable, like the earlier Mesozoic, for the number of Ammonites and Belemnites among its marine species; for the diversity and size of the Rep- tiles populating the seas, land, and air; for Birds that had teeth like the Reptiles ; and for Marsupial and Oviparous Mammals. Unlike the earlier Mesozoic, it is not less remarkable for the existence in the seas, along with Ganoids and Cestraciont and other Sharks, of Teleost Fishes, related to the Perch, Mackerel, and Salmon, and for the addition to the forest trees of Angiosperms of kinds related to the Sassafras, Magnolia, Tulip Tree, Plan- tain, Fig, Beech, and the like, together with Endogens of the tribe of Palms. GENERAL SUBDIVISIONS. Only the grander subdivisions of the Cretaceous series, the LOWER Cre- taceous and the UPPER, or the EARLIER and LATER, are adopted alike in Europe and America. But it is not yet established that the limits between these two divisions as recognized on the two continents are the same. NORTH AMERICAN. 1. General Geographical Features of North America. The map here introduced presents a general idea of the distribution of land and salt water over the continent of North America during the period MESOZOIC TIME CRETACEOUS. 813 of greatest submergence in the course of the Cretaceous period. The vertical lining indicates the parts that were submerged during the Lower Cretaceous ;. the horizontal lining, those that were submerged during the Upper Creta- ceous ; and the cross-lining, the areas under water through the whole period. The map is too small for an indication separately of the fresh-water Creta- ceous areas. 1349. North America in the Cretaceous period. The positions of the areas of Cretaceous rock-making, as illustrated for the most part on the map, are the following : 1. The Atlantic border. 2. The Gulf border to the Mississippi River. 3. The Western Gulf border, or the area of Texas and Mexico. 4. The Western Interior Continental Sea, including the summit region of the Rocky Mountains, and extending south through New Mexico and western Texas into Mexico. 5. The Pacific border. Besides these there are the independent areas of Arctic lands. The submergence reached its maximum during the earlier half of the Upper Cretaceous. During the progress of Lower Cretaceous time, the great Western Interior region was, for the most part, at or near the water level ; for the outcropping beds are fresh-water or marsh-made formations. Only in its southern part from Kansas over Texas, part of New Mexico and Mexico, are they marine. At the same time the Atlantic border and the northern Gulf border had their fresh-water formations. But after the Upper Greta- 814 HISTORICAL GEOLOGY. ceous period had made some progress, the waters of the Mexican Gulf began to spread northward over the subsiding Continental Interior ; and before its earlier half had passed, the submergence had reached its maximum. A vast Mediterranean Sea extended from the inner portion of the Mexican Gulf, probably to the Arctic Ocean. The Atlantic border, south of New York, as the map shows, was also submerged, and a wider portion of the Gulf border ; and along the valley of the Mississippi the waters stretched north- ward beyond the present mouth of the Ohio, making a great Mississippi Bay, which was 100 miles wide in the latitude of Memphis. But in Mexico, at this time, the large Lower Cretaceous area over which the Atlantic and Pacific had been exchanging waters, was, to a great extent, emerged. Over the Pacific coast region there was a narrow strip of water narrower than in Jurassic time because of the making, at its close, of the Sierra Nevada and other mountain ranges to the north. At the time of maximum submergence during the Upper Cretaceous, the American Mediterranean Sea of the period had a length, if extending to the Arctic Ocean, of about 3000 miles. The decline in depth and size began perhaps by the middle of this later half of the Cretaceous period. As explained in detail beyond, there were successively : a shallowing of the sea and an emergence of dry land far north in British America, cutting off connection with the Arctic Ocean, and thus converting the waters on the south into a Mexican Gulf, 2000 miles or more in length ; a contraction of the great gulf commencing along the eastern border ; the conversion of the gulf, while still 1500 miles in length, into a region of alternating brackish waters and fresh waters and low marsh-covered lands, situated along and just east of what is now the Rocky Mountain section of the Western Continental Interior ; the disappearance of the salt waters, leaving only fresh waters ; and, finally, the disappearance of these waters over the mountain region, and the end of Cretaceous deposition, with a change in the events to moun- tain-making. The preceding map, illustrating North America in the Cretaceous period, was pre- pared for this work chiefly by J. S. Diller and T. W. Stanton, of the U. S. Geological Survey, from the map by C. A. White in his paper On the Correlation of the Cretaceous ( U. 8. G. S. Bulletin, No. 82, 1891), and from those for British America by G. M. Dawson in the Transactions of the Royal Society of Canada for 1890, and largely from later papers since published, and more recent results in possession of the U. S. Geological Survey. White's Bulletin, which contains a review of the literature, facts, and theories pertaining to the North American Cretaceous formation, has been of much service in the preparation of the following pages. SUBDIVISIONS. No general subdivisions of either the Lower or Upper Cretaceous for all the regions in North America have been adopted, on account of the wide diversity of the regions as to conditions. Part of the deposits being fresh water, and the marine fossils of the Atlantic and Pacific borders and of the MESOZOIC TIME CRETACEOUS. 815 Atlantic and Continental Interior being almost completely unlike, it has proved very difficult to determine equivalency. The Lower Cretaceous series is less well displayed on the Atlantic and Pacific borders than in Texas, and hence the division into epochs has been based on the subdivisions recognized in the latter region. For a like reason the epochs of the Upper Cretaceous are based on the subdivisions over the Con- tinental Interior. The principal subdivisions in each of the geographical belts are given in the following tables. The equivalency indicated is, for the reasons stated, largely doubtful. For comparison, the corresponding subdivisions in Euro- pean geology are presented in the last column. 1. LOWER CRETACEOUS DIVISION. Atlantic and Northern Gulf Borders Western Gulf Bor- der, Texas Rocky Mountain Region Pacific Border Europe 3. Gault or Albian 1, 2, 3, Potomac group, Atlantic border ; Tusca- 1 3. WASHITA EPOCH 2. FREDERICKS- Horsetown 2. Aptian or Lower Greensand 1 loosa group, Ala.; a BURG EPOCH | Eutaw in Miss. ' 1. TRINITY EPOCH 1. Kootanie Group Knoxville >1. Neocomian 2. UPPER CRETACEOUS DIVISION. Atlantic Border Northern Gulf Border Western Gulf Border, Tezas Continental Interior and Rocky Mountain Region Pacific Border Europe Unrepre- sented ? Laramie in 4. LARAMIE EPOCH 2. Upper Laramie DANIAN Maestricht 4 - Upper Unrepresented? western or beds Greensand Texas Denver group in part. 1. Lower Laramie {Middle Eipley group; f 2. Glauconitic 3. MONTANA EPOCH SENONIAN Greensand part of Rotten group 2. Fox Hills group _ Lower limestone j 1. Ponderosa 1. Fort Pierre group Greensand [ marls Chico group, Lower part of or upper 2. Clay marls? Rotten lime- {2. Austin 2. COLORADO EPOCH . part of the TURONIAN stone. Upper limestone 2. Niobrara group Shasta- Eutaw beds ; 1. .Eagle Ford 1. Benjton group Chico series Tombigbee shales 1. Raritan sands Lower Cross- 1. DAKOTA EPOCH CENOMANIAN group Timber sands Dakota group The lower limit of the Cretaceous series in North America has been made out by a comparison of fossils with those of the Neocomian of Europe. It is especially marked, in most localities where the remains of plants occur, by the presence of the leaves of the earliest species of Angiosperms, along with those of the still abundant Cycads. As at present understood, the 816 HISTORICAL GEOLOGY. series extends as far upward in the geological formations as the remains of Mammals are of the oviparous kinds, with none of the ordinary or placental Mammals, and as far as the remains of Reptiles include the Mesozoic types of Dinosaurs and Mosasaurs ; and, moreover, until the epoch of mountain- making, which closed Mesozoic time, had reached its climax. No marine fossils of the Cretaceous beds, or remains of Cretaceous Vertebrates, are positively known to be continued from the Cretaceous into the Tertiary formation. ROCKS KINDS AND DISTRIBUTION. 1. LOWER CRETACEOUS. Atlantic border. The Potomac formation. The Lower Cretaceous beds of the Atlantic border are those of the fresh-water Potomac formation, so named by W. J. McGee in 1888. It consists mostly of granitic sandstones and con- glomerates, loosely aggregated and irregularly bedded, with clay-beds chiefly in the upper portion. It occurs on the Atlantic border near the inner limit of the Cretaceous, in an interrupted belt, passing through Delaware, Maryland, the District of Columbia, Virginia, and beyond to Weldon in North Carolina. The thickness is 600 feet and less. The width of the belt where continuous is seldom over 10 miles ; but outliers make its probable original width in some parts perhaps 40 or 50 miles. The coarser conglomerates occur in the vicinity of the larger rivers, the Delaware, Schuylkill, Susquehanna,. Potomac, and James River, showing that the rivers had then their place over the Atlantic border, and also that their floods were concerned in the coarser deposition, while the finer materials and clays mark off the relatively quiet areas and intervals. The presence of a rare marine shell shows that the sea was not far away. The granitic material is that of the rocks over much of the region adjoining, and of the Triassic, which in some cases they overlie. But the other sands are probable evidence that the drainage over the Atlantic border had now its head in the Appalachian Mountains. According to Fontaine, its plants, which include Cycad stumps and leaves, Conifers, and Angiosperms, range in types through the whole of the Lower Cretaceous of Europe, and include some species that are related to those of the first division of the Upper Cretaceous. According to L. F. Ward, the Cycad stumps occur in the lower part of the Potomac group, the same that includes the Kappahannock freestones. He states, also, that on James E/iver, Virginia, the beds contain Cycads and Sequoian trunks without Angiosperms, suggesting the idea that they are perhaps lower in the series. Northern Gulf border. The Tuscaloosa group in Alabama so named by E. A. Smith and L. C. Johnson consists of clay-beds and sand-beds, containing impressions of leaves. The Eutaw group, in Mississippi, 300 to 400 feet thick, has similar characters, and contains some lignite (Hilgard, 1860). MESOZOIC TIME CRETACEOUS. 81V Western Gulf border. In Texas, and to the north and northeast in Indian Territory and Kansas, west and northwest in New Mexico, and west and southwest in Mexico, the Lower Cretaceous beds are mainly marine. They are the Comanche series of R. T. Hill. They have fresh-water beds at bottom, but consist above largely of thick limestones, which are partly chalk. They abound in fossils, and indicate, for the most part, the presence of pure subtropical oceanic waters. The thickness is 1000 to 2000 feet in central Texas, and 5000 feet on the Rio Grande. The subdivisions adopted by Hill (on which the division of the Lower Cretaceous into epochs is based) are as follows : 3. WASHITA EPOCH. Washita group. 4. Shoal Creek limestone. 3. Denison beds, sands, clays, limestones ; Exogyra arietina clays. 2. Fort Worthy or Washita, limestone. 1. Preston beds, Duck Creek chalk, Kiamitia clays. 2. FREDERICKSBURG EPOCH. Fredericksburg group. 3. Caprina limestone, Austin marble. 2. Comanche Peak chalk. 1. Walnut clays, with Exogyra Texana and Gryphsea Pitcher! of Rcemer (G. mucronata of Gabb). 1. TRINITY EPOCH. Trinity group. 3. Paluxy sands. 2. Glen Hose beds, sandy below, calcareous above, containing marine fossils and some vegetable and Reptilian remains. 1. Trinity sands, with fossil leaves and lignite. As above indicated, the Cretaceous limestones of Texas are partly chalk, like the Cretaceous of southern England ; and the chalk contains flint. Chalk, as already explained, is made from sea-bottom accumulations consisting largely of the minute shells of Rhizopods, corresponding to the Globigerina ooze of modern seas ; and flint, from the siliceous spicules of sponges and siliceous shells of Diatoms or Radiolarians that may exist in the same calca- reous deposits. Chalk is supposed to show therefore that the seas in which it was formed had a depth of at least some hundreds of feet. The various fossils in the beds are also evidence of deep water. The beds continue to be thick over the Indian Territory, but thin out in Kansas. The Ouachita Mountain range was emerged land, and the Cretaceous sea, as Hill observes, had a shore line at its base. In Mexico, the Lower Cretaceous, on the map of Castillo (1891), extends nearly to the city of Mexico ; and it is continued beyond to the southward and westward, in isolated patches. According to Hill (1893), all, except a small portion to the northeast, is a continuation of the Comanche group of Texas, but with less distinct subdivisions ; and he concludes further that DANA'S MANUAL 52 818 HISTORICAL GEOLOGY. over Mexico during this time the Atlantic and Pacific oceans were united. He makes the thickness 20,000 feet. Rocky Mountain region and Central Interior. The Lower Cretaceous of the Rocky Mountain region includes, at some localities at base, the fresh-water Kootanie beds of Dawson (1885), so named from the Kootanie Pass, in the Rocky Mountains, about 30 miles north of the 49th parallel, where they were first found and characterized by their fossil plants. The beds are sandstones and shales, and contain some coal. Other localities occur at intervals to the northward for 150 miles, and to the southward in western Montana. The beds also outcrop, according to recent determinations by L. F. Ward, about the Black Hills, in western Dakota, where they have a thickness of 200 to 300 feet, contain trunks of Cycads and other plants, and underlie plant beds of the Dakota group (Upper Cretaceous) to which they had been referred. How far they extend eastward and southward is not yet ascertained. In New Mexico they are mainly marine beds, and resemble those of Texas, with which they are continuous. Pacific border. The Lower Cretaceous beds of the Pacific border in the United States are marine, but in British Columbia they are partly of fresh- water or marsh origin. They occur (1) in the Plateau or interior region of British America, and (2) along the Coast belt. Over the Plateau region they are described as extending over Washington to the Yukon district and northward to the Arctic Ocean (G. M. Dawson). The Plateau region within the United States, that is, the Great Basin, was apparently emerged; but south in Mexico, as already described, long sub- mergence is proved by the existence of many thousand feet in thickness of Lower Cretaceous beds. The coast region has a border of Lower Cretaceous beds along the greater part of California and Oregon, and also on Queen Charlotte Islands and Vancouver Island ; and again far north along both the northern and southern shores of the Alaskan peninsula. The beds in California constitute the Shasta group of J. D. Whitney (1869). They are well exposed along the western border of the Sacramento valley, where they are divided into the Knoxville and Horsetown beds so named from localities in the region by C. A. White. These two groups were made by White to represent only part of the Shasta group ; but later observations by Diller and Stanton (1893) show that they correspond to the whole. In Tehama County the total thickness is about 26,000 feet ; in Shasta County, where the Horsetown beds alone occur, 5200 feet (Diller, Stanley-Brown). The Knoxville or lower group has among its fossils various forms of Aucellce (Figs. 1203-1205, page 759), and the Horsetown includes in its abundant fauna many Ammonites ; the species of the two have close relations to the Neocomian, Gault, and intermediate beds of Europe. The two groups in California thus cover the whole of the Lower Cretaceous ; and these are continued in the Chico series of. the Upper Cretaceous (Diller). In British America, the lower part only of the coast Cretaceous on Van- MESOZOIC TIME CRETACEOUS. 819 couver and Queen Charlotte Islands is referred to the Lower Cretaceous. On Queen Charlotte Islands, fossil plants of Lower Cretaceous species occur in the beds, as first discovered in 1872, and reported in the following year by Dawson. G. M. Dawson makes five subdivisions of the beds ; and the three lower, C, D, E, 9500 feet thick, are now regarded as identical with the Shasta group, on the basis of several common fossils (Whiteaves, C. A. White, T. W. Stanton). Arctic Ocean. On western Greenland, in the vicinity of Disco Island, there, are deposits containing Cretaceous and Tertiary plants, and the lower part are the Koine group, of Heer (1882), referred by him to the Neocomian of Europe, and by Newberry and Fontaine to the age of the Kootanie and Potomac. A portion of the Potomac formation in Maryland was referred, on account of its stumps of Cycads, in 1860, by P. T. Tyson to the " Wealden" ; and in 1875 to the same by W. B. Rogers. A careful study of the many fossil plants led Fontaine (1889) to essen- tially the same conclusion. The remains of Reptiles which it has afforded (see beyond) are pronounced Jurassic by Marsh. The Potomac formation in the region of the Chesapeake Bay, in Maryland, is described by N. H. Darton (1893) as overlaid by beds of white sand, gravels, and brownish sand- stones, which he calls the Magothy formation. It contains lignite and plant remains ; but no fossils are mentioned for identifying or distinguishing it ; and its separation from the Potomac by a plane of erosion is of uncertain importance. The Albirupean group of Uhler (1888) consists chiefly of white sand-beds occurring along the Chesapeake Bay, and is largely exposed near the head of Magothy River ; and it is supposed to belong in part with the Potomac formation. But such evidence is very doubtful; for the deposits of sand, mud, and gravel now forming about Chesapeake and Delaware bays, and elsewhere along the Atlantic border, show that kinds of material, color, coarseness, texture, struct- ure, are nearly valueless characters for determining the equivalency of Cretaceous and later-time beds as well as those of earlier time. All sorts are formed cotemporaneously, and the same sorts at successive epochs. On the Gulf border, the Tuscaloosa group in Alabama, as described by Smith and Johnson, consists of clayey layers with intercalated beds of sand ; it outcrops beneath and either side of Tuscaloosa, along the northern limit of the Cretaceous belt. The thickness is about 1000'. The Eutaw beds of Mississippi, first described by E. W. Hilgard, are referred to the group, as far as non-marine, by C. A. White. The Tuscaloosa group is described in detail by E. A. Smith and L. C. Johnson, in Bulletin 43, U. S. Greol. Surv., 1887, and some observations are added on the Eutaw group in Mississippi. In Texas, the Lower Cretaceous has a thickness to the northeastward, at Red River, of 1000' ; to the southwestward, on the Rio Grande, of 5000' ; and northwestward it extends into New Mexico. At Kent, 163 miles east of El Paso, the westernmost station in Texas, the thickness is made about 600' by Durable and Cummins; 550' of it belong to the Washita division, and are characterized by the Gryphcea dilatata var. Tucumcari of Mar- cou, a fossil well known from the Cretaceous of New Mexico. In Kansas, the whole thickness is but 150', half of it Trinity sands, and the rest, the Fredericksburg beds (Cragin). The more important older investigations in Texan geology are those of Ferdinand Roemer (1852), B. F. Shumard (1856-1860), Marcou (1854-1859). Shumard made the Washita and Comanche Peak groups Upper Cretaceous ; and Marcou placed the upper line of the Lower Cretaceous between these 'two groups, with the Comanche Peak lime- stone above. 820 HISTORICAL GEOLOGY. The Lower Cretaceous of northern Mexico, in Chihuahua and Coahuila, was described by C. A. White in 1889, who speaks of the strata of bluish limestones as strongly upturned and flexed, and having a thickness in the Sierra San Carlos of 4000'. Felix and Lenk, in their memoir of 1890, 1891, separate from the Cretaceous of Texas a lower part, consisting of gray to black limestones having intercalated clays as the Lower Cretaceous, and refer the rest, which consists chiefly of whitish, somewhat cherty limestones, to the Upper. He reports the former as having nearly three fourths of its 46 species of described fossils identical with the Neocomian of Europe ; and the latter as containing Radiolite-like forms, with species of Caprina and Nerinea. The Kootanie beds of Montana, which in some places contain beds of coal 12' thick, were described by Newberry in 1887, and by H. Weed in 1872. The Knoxville and Horsetown beds, i.e. the Shasta portion of the Shasta- Chico series, have a wide distribution along the Pacific coast, extending with interruptions from south- ern California probably to Alaska. Their greatest development, according to Diller, is upon the western border of the Sacramento valley of California, where they are composed chiefly of shales with only occasional sandstones above and many thin beds below. The beds are rarely calcareous, and where the successively newer overlapping series come in r lying unconformably on the pre-Cretaceous metamorphic rocks, local conglomerates are common. The greatest thickness of the Knoxville beds measured is nearly 20,000'. The absence of faults is not assured. The Horsetown beds have a thickness of over 6000', and overlap the Knoxville beds in all directions toward the Cretaceous shore. The conforma- bility of the Knoxville and Horsetown beds and their detrital and faunal continuity in both California and Oregon indicate uninterrupted sedimentation ; and the shoreward overlapping of the newer beds, with marked unconformity upon the pre-Cretaceous rocks, shows that upon the Pacific border the land was subsiding and the sea encroaching. 2. UPPEK CRETACEOUS. Atlantic Border. On the Atlantic border the Upper Cretaceous formation outcrops from Martha's Vineyard, along the islands south of New England to New Jersey ; thence it continues southward, in a narrow belt by the west side of the Tertiary to southern Virginia. It occurs in North and South Carolina only in small patches. Near Macon, G-a., a belt commences north of the Tertiary area, which widens westward, and, on approaching the Mississippi valley, spreads northward up its east side to the Ohio near Paducah; where it crosses the river and narrows out in an area of sandy clays and " micaceous sands " like those of the Kentucky Cretaceous beds. The rest of the Missis- sippi Bay of the Cretaceous Period became covered later by Tertiary beds and fluvial deposits. The formation along the New Jersey coast includes at bottom a fresh- water group, called the Raritan, and, above this, beds of greensand or marl interstratified with beds of common sand, clay, and occasionally of marine shells. Remains of Reptiles are sometimes found in the upper beds, and occasionally a complete skeleton. The subdivisions as laid down by G. H. Cook are given in the following table ; and the epochs to which they probably belong are also stated. MESOZOIC TIME CRETACEOUS. 821 4. LARAMIE EPOCH. Unrepresented ? Possibly here the Upper Ghreensand, Manasquan group of W. B. Clark : 15 to 20 feet thick of greensand, with above, sandy clays and blue marl ; fossiliferous. 3. MONTANA OB KIPLEY EPOCH. 2. Middle Grreensand, Eancocas group of Clark : about 45 feet of marl, with as much of yellow sand above ; fossiliferous. 1. Lower Greensand, Navesink group of Clark: 30 to 45 feet of greensand, and above this a red-sand stratum, 100 feet thick; with below Clay marls, 250 to 300 feet. 2. COLORADO EPOCH. Unrepresented ? or perhaps the Clay marls. 1. DAKOTA EPOCH. Raritan group or Plastic clays : thick beds of plastic clay with some interstratified sand-beds; more sandy above; 350 feet; fossil leaves and lignite, especially toward the base (one third of the thick- ness from its base in New Jersey) ; shells rare, and these freshwater of the genus Uhio, or brackish-water Gastropods. The Raritan group is proved by its remains of plants to be the probable equivalent of the Dakota of the Continental Interior ; and the Lower Green- sand group, by its fossils, as well brought out by Whitfield, to be the equiva- lent of the Ripley group of the Gulf border. Whitfield refers to the same group, but doubtingly, the nearly unfossiliferous Clay marls which lie below it. The Upper Greensand group graduates, without a break in the stratification, into the overlying Eocene Tertiary, as if its formation were, like the Upper Lara- mie, the closing work of the Cretaceous period. If not so, the Laramie epoch is not represented on the Atlantic border. The Lower Greensand is the most fossiliferous of the series. Whitfield has described from it 19 species of Cephalopods, 127 of Gastropods, 155 of Lamellibranchs, and 2 of Brachiopods, or a total of 303 species, against 47, under the same tribes, from the Middle and Upper Greensand groups. Not- withstanding the unbroken passage of the Upper Greensand group into the Eocene Tertiary, out of the 79 Eocene species of Mollusks described by Whitfield, none occurs in the underlying Cretaceous. The clay of the Raritan group is partly pure white clay, but it varies to gray, yellow, and red in color, owing to traces of iron oxide, and in some places to black in consequence of disseminated fragments of lignite which had been gathered from some lignitic bed. In general, it is not laminated clay, like that of nearly all river valleys, but a massive clay free from lami- nation and of remarkable purity. The best of it has great value for the manufacture of fine pottery and other purposes. The Raritan formation, with its massive clays of various colors, occurs 822 HISTORICAL GEOLOGY. also on Staten Island. It -includes the clay-beds of northern Long Island, which are well displayed at Glen Cove, and at various points between this place and Huntington and farther to the eastward ; and also part of the clays of Fisher Island, Block Island, and Martha's Vineyard. Gay Head,, the west cape of Martha's Vineyard, owes its name to the variously colored clay-beds. The several beds of greensand, or marl, consist of common sand and black- ish to olive-green grains of glauconite a silicate of iron and potash made chemically within the cavities of the shells of Rhizopods, Corals, and other marine organic materials. The bluffs after a rain often look black or green- ish black. They are called marl-beds because the material is useful as a fertilizer. The fertilizing properties of the marl, according to G. H. Cook, are not due to the potash of the glauconite, but to the presence of some lime phosphate. The fresh-water origin of the New Jersey clay-beds is generally recog- nized. The absence of lamination and the thickness indicate, not river action, but the existence of quiet fresh-water areas parallel with the New Jersey seacoast and that of southern New England from New Jersey eastward as far as Cape Cod, or about 300 miles. The coast-line may have been some miles distant to seaward. Rivers were not the transporters, for they do only coarser work. No river in New England, where f eldspathic rocks abound, is now making such non-laminated clay-beds. Only small streamlets and rills, could have been concerned ; and the feldspathic rocks must have been near by. For New Jersey the Triassic granitic sandstones may have been the feldspathic rocks at hand ; and for Long Island and the islands to the east- ward crystalline rocks were not far away to the northward. The bleaching of the deposits in the case of the white clay-beds required the action of carbonic acid or organic acids proceeding from the decomposition of beds of peat or leaves underlying the Raritan or intercalated with its layers; for the clays from granitic rocks always derive a tinge of iron oxide from the black mica and other iron-bearing minerals among their constituents. The origin of the clay-beds in all these particulars was very much like that of those of the coal-formation (page 665). After the making of the Raritan beds, the sea regained access, as the marine shells evince, to the shore region of the Atlantic border ; and this was the first submergence of the border since the close of the Lower Silurian. The geanticline, which was probably increasing through the Paleozoic, at last had disappeared. The beds of greensand are supposed to have been formed in moderately deep waters off the coast. The least depth required for the production of greensand is not known. Ehrenberg, who first discovered that the grains of glauconite often have the shape of casts of Rhizopod shells, also detected them in the bones of the Zeuglodon of the Ala- bama Tertiary, which were probably in shallow water when the formation took place. J. W. Bailey reported in 1856 their occurrence in the cells of recent Corals and Rhizopods, MESOZOIC TIME CRETACEOUS. 823 over the sea bottom near Cape Hatteras, at depths of 40 or 50 fathoms. Similar facts were obtained abundantly by the ' ' Challenger " Expedition, as mentioned by Murray. But glauconite grains have been observed also as a covering of stones and in their clefts, and sometimes as the coloring material of concretions of silica in the form of opal (Cayeux). The ingredients for maKing glauconite must be derived from the sea water or sea bottom, or partly from organic matters at hand. It has been suggested that the silica may, in some cases, have come from minute sponges that had previously grown in the cells which it occupies. The equivalency of the Karitan clay -beds of New Jersey and those of Staten Island and Long Island was announced in 1843 by W. W. Mather, on the ground of their resem- blances. It was proved for Staten Island and Long Island from the fossil leaves, by New- berry in 1874, and for Martha's Vineyard by C. D. White in 1890. Since the latter date the number of known Cretaceous plants has been increased by the discoveries of A. Hoi- lick. Newberry pointed out the identity of some of the Raritan plants with those of the Dakota group. Northern Gulf Border. The Upper Cretaceous beds of Alabama and Mississippi, in the northern Gulf border west of the Florida peninsula, comprise the following groups : 4. LARAMIE EPOCH. Not represented. 3. MONTANA OR BJPLEY EPOCH. Ripley group: hard white limestone 200 to 300 feet thick, often sandy, with but little green sand or glauconite in the beds. Also the upper part of the Rotten limestone. 2. COLORADO EPOCH ? Lower part of Rotten limestone: hard or soft chalky limestone; total thickness of Eotten limestone 500 to 1200 feet. 1. DAKOTA EPOCH ? ; possibly Lower Colorado. Upper Eutaw beds of Alabama ; Tombigbee sands of Mississippi. The limestones on the Gulf border diminish in thickness to the eastward and fail wholly in Georgia, where, according to J. W. Spencer, the Florida axis probably determined the eastern limit of the Cretaceous belt. The beds in that state consist of mixed clays and sands, and are about 1385 feet thick, with few fossils. They look, according to Spencer, as if -made from sedi- ments of fluvial origin. The Kipley group, as brought out in Whitfield's paleontological report, is; the equivalent of the Lower Greensand group of the New Jersey Cretaceous,, and of its continuation through Delaware, Maryland, and North Carolina. In view of the much better preservation of the fossils on the Gulf border, Stanton speaks of the Ripley fauna as having this wide range. The number of identical species along the Atlantic and Gulf borders is large, as shown in the lists of species given beyond. 824 HISTORICAL GEOLOGY. In Tennessee and Kentucky, the Ripley group is represented chiefly by micaceous clays and sand-beds ; and, while the thickness is 400' to 500' in Tennessee, it becomes a few scores of feet in Kentucky. Below it, in southern Tennessee, lie 200' to 300' of beds, sparingly calcareous, repre- senting the Rotten limestone, and at bottom, the " Coffee sands of Safford, 200' thick" ; which are Lower Cretaceous. The age of the beds below the Ripley group on the Gulf border, as Stanton remarks, is not clearly defined by the fossils, and the Colorado epoch is therefore not known positively to be represented. The Rotten limestone contains many Ripley fossils. During the Laramie epoch, according to White and Stanton, the Atlantic and Gulf borders were probably somewhat emerged, the Ripley beds being covered directly by beds with Eocene fossils. Western Gulf Border. In Texas, the Upper Cretaceous beds are 2000 feet thick (E. T. Hill). There are sand-beds and clays at base which are non-marine ; and above these thick beds of limestone with much chalk, followed by marls and greensand. They extend northeastward into Arkansas, and westward through the Trans- Pecos region and its mountains, to northeastern Mexico, where they occur in the states of Chihuahua, Coahuila, and Tamaulipas, chiefly along the mountain region between Presidio del Norte and Tainpico, resting on the Lower Cretaceous conformably, although upturned. The subdivisions, as determined by Hill, are as follows : 4. LARAMIE EPOCH. Laramie series in western Texas. 3. MONTANA EPOCH. Exogyra ponderosa marls, with glauconitic (or greensand) beds (Navarro beds, Eagle Pass beds) above : chalk, overlaid by marls and greensand. 2. COLORADO EPOCH. 2. Austin limestone, or Austin-Dallas chalk ; 300 to 500 feet thick. 1. Eagle Ford shales; 500 feet thick. 1. DAKOTA EPOCH. Lower Cross Timber sands; 300 feet thick. The beds are marine, excepting the sand and clays of the Lower Cross Timber sands, and some beds of the Eagle Ford shales. The fossils are all different from those of the Lower Cretaceous beds. The Glauconite group contains over 40 species of fossils, identical, according to Stanton, with those of the Eipley fauna, and many also of the species of the Montana group in the Continental Interior. Continental Interior. The Cretaceous beds of the Interior Continental Sea were early studied by Meek and Hayden, and their subdivisions in the main are those still in use. MESOZOIC TIME CRETACEOUS. 825 4. LARAMIE EPOCH. 2. Upper Laramie or Denver group: fresh-water beds of sand- stone, conglomerates ; and partly of eruptive material (andesytic, etc.) ; with or without coal-beds. 1. Lower Laramie : fresh-water beds of coarse, friable sandstones, often cross-bedded, with clay-beds ; occasional fossiliferous brackish- water beds ; with beds of bituminous coal, in some places " 15 to 20 coal-beds in 1000 feet ; " thickness 1000-5000 feet. 3. MONTANA EPOCH. 2. Fox Hills group: sandstones and shales with many marine fossils ; maximum thickness, 1000 feet. 1. Fort Pierre group : plastic clays, sand-beds often with limestone concretions ; marine fossils ; maximum thickness 7700 feet. :2. COLORADO EPOCH. 2. Niobrara group: calcareous marls, chalk, shales, sandstones, with limestones ; marine fossils ; maximum thickness 2000 feet. 1. Fort Benton group (near Fort Ben ton) : laminated clays, lime- stone, with marine fossils ; maximum thickness, 1000 feet. Probably includes the Coalville coal-bed, with 1500 feet of the lower part of the Coalville group. 1. DAKOTA EPOCH. Dakota group: sandstones, clays, some lignitic layers, with con- glomerates sometimes at base; fossil leaves abundant, and other evidences of fresh-water origin, and little of brackish or marine waters. Probably includes the Bear River coal-beds. The grouping of the subdivisions adopted above (which accords with the results of Meek's paleontological work) and the terms used are those of G. H. Eldridge. The name, Lignitic, used by Meek and Hayden for the Upper division (which they made Lower Tertiary), was changed by King in 1878 to Laramie. Subdivisions of the Laramie into Lower and Upper is based chiefly on the work of Cross (1888 and later). The Cretaceous was the coal period of western America. As Paleozoic time, the era of extended continental submergence, closed with the slow emergence of the eastern half of the continent, so Mesozoic time, the era of extensive submergence of the western half of the continent, closed with the slow emergence of this western half. And the later coal-beds, like the earlier, mark long periods of small emergence and persistent marshes in the alter- nating conditions of level. The Upper Cretaceous affords coal at different levels : at Bear River, western Wyoming, and at Mill Creek, British America, in the Dakota group ; at Coalville, Utah, in the Colorado group (Stanton) ; and at Dunvegan, Peace River region (117-J W., 56 N.) (Dawson) ; in the Belly River region, north of Montana, on Vancouver Island, at Nanaimo and 826 HISTORICAL GEOLOGY. Comox, and in the Bow Eiver region, north of Montana, probably in beds of Montana age (Dawson). But the coal-beds are mostly in the Laramie formation. They are worked for coal in Colorado, Utah, Wyoming, Montana, and New Mexico. In Colo- rado alone the coal-fields have an aggregate area of about 18,000 square miles (R. C. Hills, 1892). The beds are often five to six feet in thickness, and one at Evanston, in western Wyoming, has been described as 26 feet thick. In British America, at Edmonton (1131 W. 53^ K), and in the Souris dis- trict, there are Laramie coal-beds. In Gunnison County, Col., at Crested Butte, a bed of anthracite five feet thick is worked ; and in New Mexico, at the Old Placer Mountain, eight miles east of San Antonio, is another locality of anthracite. The anthracite is a. result of alteration by the heat of eruptive rocks. To appreciate the position and width of the Cretaceous seas over the- western Continental Interior during the Colorado and Montana epochs, and especially the Niobrara portion of the former, the reader should refer again to the map on page 813 ; and, still better, to some colored geological map of North America. Their eastern border extended, from what is now western Texas, east- ward and northward over central Kansas, and thence along eastern Nebraska and Dakota into British America. In the western portion of these interior waters there were the large Archaean islands of the protaxis, high lands and low lands varying in limits with oscillations in level, which were mostly forest-clad, and well populated, as evidence shows, by Mammals, Amphibians, and Reptiles, the Reptiles taking the lead in size and power. Beyond these islands the seas spread still westward over nearly all of Wyoming arid Utah to a line passing southward through Great Salt Lake, where the western shores lay along the lands of the Great Basin. In the progress of the Upper Cretaceous, the non-marine Dakota epoch was followed by a second, the COLORADO, in which the Interior sea gradually attained ocean-like conditions, and was inhabited by great Mosasaurids or Pythonomorphs, and Sea-Saurians related to the Plesiosaurs, as well as Sharks and Saurodont Fishes. Even before the Niobrara beds had all been deposited, a shallowing had begun in Kansas. S. W. Williston states that in the beds of Kansas Invertebrates abound; that Reptilian remains are unknown in the lower part of the Niobrara beds within 100 feet of the base, but higher up are common fossils. " Species of two or three genera of Mosasaurs occur at different levels, but those of Clidastes [Edestosaurus of Marsh] only in the upper part. Turtles are rare in the lower portion, while very common in the uppermost beds." This shallowing was general over the Continental Interior as the Colorado epoch closed. Moreover, the Colorado fauna, in some unexplained way, disappeared. During the Montana epoch the waters, however, were still salt, and marine life was abundant, and included Plesiosaurids. But the shallowing was continued ; and in the following Laramie epoch the waters MESOZOIC TIME CRETACEOUS. 827 were, to a large extent, fresh, and only occasionally, or else locally, brackish. Moreover, at many intervals, great areas emerged which were speedily covered with marshes and forests in the warm and moist climate, and thus peat-beds were made, which later became coal-beds. The length of the Laramie Interior Sea in this condition was nearly 2000 miles, it reaching to the parallel of 57 N. ; and another, the Mackenzie valley area, opening on the Arctic Ocean, was 500 miles long. The southern of these Laramie areas was probably tidal as well as the northern. For the width south of 49 K. was 600 to 800 miles, which is too great for fluvial waters. Besides, the strata are generally cross-bedded in stratification, and they include occasionally conglomerates, proving seemingly strong move- ments in opposite directions, and at times in some parts violent currents. Moreover, although the waters were generally fresh, still Sea-Saurians, Sharks, and other marine species occasionally ascended to Dakota and beyond. The bay received the drainage from all the bordering lands for the 2000 miles from the Mexican Gulf to the limit of the Laramie beds in British America ; and hence a great amount of fresh water flowed southward toward the outlet. Hence the tides from the western part of the gulf generally carried in salt waters for a short distance only, and thence the tidal movement was propagated northward by the fresh waters. But occasionally the Gulf waters were able, through a subsiding in the land, to flow far north- ward, and let in the Sea-Saurians, and Sharks, the Oysters, and other Sea- Mollusks, so as to make the brackish-water fossiliferous beds of the Laramie formation. The spawn of Oysters and other Mollusks would have been rapidly transported. If the above explanation of the conditions in the Laramie epoch is correct, the distance to which the salt waters of the Gulf were carried in westward and northward, whether one mile or many, is a subject for investi- gation. The Laramie beds derived their material from the land on the borders of the Interior Sea. The existence of Paleozoic and Mesozoic rocks of various ages about the base of the Black Hills, where there is also the Cretaceous formation, indicate how the other adjoining Archaean lands may have been skirted, where now covered by Tertiary beds and those of the later Cretaceous. The Upper Laramie or Denver group was first defined by Cross and Eldridge in 1888. It derives the latter name from its distribution about the city of Denver, east of the Front Range (Archaean) of the Rocky Moun- tains, where it overlies the Lower Laramie. It is described as resting on the latter unconformably, the unconformity being, however, not that of bedding in a marked degree, but the unconformity consequent on the previous erosion of the beds on which the formation was deposited. The upper por- tion in that region, 1400 feet thick, consists largely of the debris of eruptive rocks, mostly different kinds of andesytes ; while the lower part, 800 feet thick, distinguished as the Arapahoe beds, is mostly made up of conglom- 828 HISTORICAL GEOLOGY. erates formed out of various older stratified rocks, some identified as Car- boniferous by their fossils. The occurrence of eruptive debris in the Laramie beds of other regions has been regarded as a probable sign of Denver age. The plants include species not found for the most part in the Lower Laramie. The Denver group has afforded Horned Dinosaurs (Ceratopsids) and other kinds, showing their Mesozoic relations. Ordinary Mammals are absent, and all other evidence of a Tertiary fauna. To the Upper Laramie are referred, by Cross, on the ground of the plants (studied by Knowlton) as well as the eruptive conglomerates and unconformity at base chiefly by erosion, beds in the Middle Park, and at other localities, from Greeley, Col., to the Katon Mountains in New Mexico ; and beds about Livingston, in Central Montana, called by W. H. Weed the Livingston beds ( U. 8. G. 8. Bulletin, No. 105, 1893). The latter, as described, have a thickness of 7000 feet, and rest over 1000 feet of Laramie beds, but were deposited, like the Denver, after a time of extensive erosion, and therefore the conformability is not perfect. The group, however, according to Weed, has a brackish-water, oyster-bearing layer, which is well packed with oyster shells, Laramie-like, at a height of 200 feet above its base, that is, above the plane of extensive erosion. In southern Wyoming, along Bitter Creek, in the vicinity of the Union Pacific Railway, near Hallville, Black Butte, Point of Rocks, Rock Spring, and elsewhere, the Laramie contains a number of coal-beds. South of Black Butte there are nine or more distinct coal-beds ; and between two of them were obtained remains of a Horned Dinosaur (Agathaumas of Cope). Beds in eastern Wyoming, called by Marsh the "Ceratops beds," are referred, with a query, by Cross to the Upper Laramie, because of the presence of Ceratopsids in both ; but to the Lower, by Marsh. They rest on 400 feet of sandstone conformably, and the sandstone directly on Fox Hills beds, and contain no eruptive debris. Besides Horned Dinosaurs of several species, the beds have afforded remains of other Dinosaurs related to the Iguanodon and Megalosaurs, and of Marsupial and Oviparous Mammals. Above the stratum containing the fossils there is a bed of coal, the Shawnee coal-bed, 10 inches thick. " Judith River" beds in northern Montana, first described by Hayden and Meek, afford Dinosaurs of the same genera, according to Marsh, as the Ceratops beds, besides many others, including Plesiosaurids ; and also re- mains of Sharks, Chimseroids, Ganoids, and, as other evidence of brackish- water conditions, shells of Ostrea, Anomia, Corbicula, Corbula, and Goniob- asis. The Fort Union beds, near the border of North Dakota and Montana, have been referred to the Upper Laramie and also to the Tertiary. They are of doubtful relations. The most eastern " Lignitic " beds referred to the Laramie are those of South Dakota, near Moreau River, west of the Missouri, in 101 W., where remains of two Plesiosaurids have been found, Plesiosaurus occiduus, and MESOZOIC TIME CRETACEOUS. 829' Ischyrosaurus antiquus, both described by Leidy in 1873. Nothing of the Laramie is recognized in Kansas. The Reptiles and other fossils in the beds referred to as Upper Laramie indicate not only their Cretaceous age, but also their close relations to the Lower Laramie. At present the line between the two divisions cannot be definitely drawn. The subdivisions of the Rocky Mountain Cretaceous, including the Laramie, were first described by Hayden and Meek. Their papers commenced in 1856, and appeared at inter- vals for 20 years. Meek's Report on the fossils, in which the stratification is reviewed, constitutes vol. ix. of the Reports of the Hayden Expedition (1876). Their subdivisions were the Dakota, Fort Benton, Niobrara, Fort Pierre, and Fox Hills. The Tertiary sec- tion in the "Upper Missouri region," described by Meek and Hayden, contained: (1) Dakota group, 400' ; (2) Fort Benton, 800' ; (3) Niobrara, 200' ; (4) Fort Pierre, 700' ;. and (5) Fox Hills, 500'. G. H. Eldridge in 1889 grouped the divisions into the three : (1) Dakota ; (2) Colorado, and (3) Montana. C. A. White had earlier recognized (1876) the same grouping under the names Dakota, Colorado, and Fox Hills. The Colorado formation and its relations to the other divisions of the Cretaceous have been reviewed in detail by T. W. Stanton ; and from his report of 1893 many of the follow- ing facts are taken. The thickness of the Upper Cretaceous series at the Black Hills is less than 1000' : (1) the Dakota, 250'-400' ; (2) the Colorado, 300'-500' ; (3) the Montana, 150'-350' (H. Newton). In Cinnabar Mountain, Montana, the total thickness, according to Weed, is about 4300' : (1) the Dakota, 526' ; (2, 3) the Colorado and Montana, 2850' ; (4) the Laramie, 935'. East of the Front Range, in Colorado, the Dakota outcrops at the base of the range, and, outside of this, the other later groups in succession, as first shown i by Marvine. In the Denver region there are : (1) Dakota, 300' ; (2) Colorado, 1100', of which 400 is Fort Benton and 700 Niobrara ; (3) Montana, 8700', of which the Fort Pierre, 7700', and Fox Hills, 800'-1000'~; (4) the Laramie with the Denver group, 2000'. The thickness diminishes southward, and between Canon City and Pueblo, on the Arkansas River, the Montana group is but 3000' thick. The section at Coalville, in Utah, according to Stanton, which is peculiar in containing a great coal-bed in the Colorado portion, con- sists as follows: (1) Dakota, 5000'?; (2) Colorado, 1560'-1660', mostly sandstone and fossiliferous, but with a heavy bed of coal at the top of the lower stratum of 500' to 600' ; (3) Montana, about 2900', of sandstone and shales, with probably 1500' of beds above; and in the part referred to the Montana group on account of the marine fossils, there are some thin plant beds, the fossil plants of which are in part Laramie. The Kansas Cretaceous consists, according* to S. W. Williston, of 350' to 400' of Dakota beds, 300' to 400' of overlying shales and limestone of the Benton group, and 400' to 450' of chalk and other beds of the Niobrara, making the Colorado series 700 ; to 850' in thickness; and above these, 50' to 100 r of beds of the Montana group. The Laramie is absent, the next beds above being those of the Loup Fork Miocene Tertiary. Newberry divided the Cretaceous of New Mexico into: (1) Dakota, 250' to 400'; (2) Colorado, 1200' to 1500' ; and (3) Montana, 1500', part of the Laramie being here probably included. (Macomb's Expl.Exp., with a review by Newberry of the conclusions he presented in Lieutenant Ives's Rep. on the Colorado River of the West.) The age of the Laramie beds (or the Lignitic, as they were called), whether Tertiary or Cretaceous, was left undecided by Meek in his report of 1870. To the Lignitic horizon he referred the Judith fiiver group, occurring at the mouth of Judith River in Montana, having there a thickness of about 415' and consisting, beginning below, of sands and clays with Unio, 100' ; impure lignite, 25' ; sand and clay-beds with shells and Dinosaurian remains, 100' ; sand and clay, 100' ; impure lignite with Ostrea, 10' ; sandy marl with some lignite and species of Ostrea, Corbicula (3 species), Goniobasis, salt-water species, 80'. 830 HISTORICAL GEOLOGY. The Fort Union group (first examined by Hayden in 1860) also was placed in this connection by Meek, on the ground of its fresh-water shells and lignite. The group was estimated by Hayden to have a thickness of 2000'. He reported it (1871) as extending southward from Fort Union, across the Yellowstone between the Black Hills and Big Horn Mountains, and northward into British America ; but the conclusions were not based on a full study of the region. The 150 feet of deposits exposed near Fort Union include three beds of impure "lignite," 1', 1-5', and 4 inches thick, alternating with beds of indurated clay and clayey sands, 20' to 70' thick containing occasionally land shells and some leaves. The age of the Fort Union beds has remained doubtful. Newberry (1890) separated it from the Laramie on the ground of differences in the plants ; L. F. Ward refers it on the same ground to the Upper Laramie. The beds in Middle Park, Col., referred to the Denver horizon by Cross, consist largely of andesytic breccia, sand-beds and conglomerates, and are 800'-900' in thickness (Marvine). They rest on upturned Cretaceous strata. Underneath the Fort Pierre group in the Belly River district, Canada, fresh-water beds occur containing fossil leaves, which have been called the Belly River group. The plants are in part identical with the Laramie (Dawson, 1886). The Dunvegan beds, on Peace River, are supposed to be of the same age. A large area has been referred to the Laramie in British America extending from the United States boundary to the 55th paral- lel, and eastward to 111 W. ; in it have been recognized a Lower Laramie or St. Mary River series ; a Middle, the Willow Creek beds ; an Upper, or Porcupine Hills beds, which correspond in fossils to the Souris River beds, just north of the United States boundary. A more eastern area extends from 49 N. to 51 N., between 102 and 109 W. In Manitoba, Central North America, the Cretaceous formation is nearly 2000' thick ; and the Montana group contains in its lower part many Rhizopod shells with some Radio- larians. The thickness of the Dakota beds in this region is 13' to 200' ; of the Colorado beds, 200' to 700' ; and of the Montana, over 1000'. The Cretaceous rests unconformably on the Devonian (J. B. Tyrrell, 1892). Fossil plants from Laramie beds in the Mackenzie River have been described by Dawson (1882 to 1889) and identified with others from Alaska. Pacific Border. On the Pacific Border, the Upper Cretaceous, or the Chico beds, occupies a broad belt extending originally from Lower California northward beyond the Queen Charlotte Islands. It formerly covered the region of the Coast and Cascade ranges, reaching the western base of the Sierra Nevada in Cali- fornia, and of the Blue Mountains in Oregon. Its eastern limit is indicated upon the map on page 813. The Upper Cretaceous of California includes only the Chico beds of the Shasta-Chico series. The Tejon, which Gabb considered Cretaceous, has been shown by Conrad, Heilprin, and White to be Eocene. The Wallala beds of White and Becker (1885), according to Dall and Fairbanks (1893), are only a phase of the Chico. The Chico beds are exposed upon both sides of the Sacramento valley. Thence they extend southward near the cOast to Lower California, according to Lindgren and Fairbanks, and northward, with local interruptions, to Jacksonville, and Riddles, Oregon ; and beneath the covering of later lavas they are supposed to connect with the Chico of eastern Oregon (Diller). The lower portion of the Chico beds consists chiefly of sandstone and conglomerate, and ranges from 900' to 1400' in thickness. In the upper portion shale predominates, excepting near the shore line where the sediments are generally coarse. The greatest thickness of the Chico, according to Diller, is nearly 4000' in Tehama County, Cal.; it thins out northward and MESOZOIC TIME CRETACEOUS. 831 -eastward, overlapping toward the Cretaceous shore, beyond the Knoxville and Horsetown beds, which form the lower part of the Shasta-Chico series. The Chico thus comes in un- conformable contact with the Jura-Trias and Carboniferous and extends inland from the Lower Cretaceous, as indicated upon the map, to the dotted line. The subsidence and consequent transgression of the sea that gave rise to the landward overlapping of the later beds of the Shasta-Chico series began soon after the great upheaval at the close of the Jurassic, and continued to at least the middle of the Upper Cretaceous (Diller). In the Tertiary the Tejon beds of California are conformable with the Chico, and they were regarded by Gabb, and also by White, as faunally continuous. The Tejon is absent in northern California, and in Oregon it rests unconformably upon the Shasta-Chico series. (Diller, 1893.) In Washington, the Puget group of White, underlying the Tejon, is a non-marine formation containing beds of coal. It extends from near the Columbia to the Puget Sound region, and is several thousand feet hi thickness. From its Molluscan and Plant remains it has been supposed by Newberry and White to represent a part of the Laramie or Tejon group. Baculites Chicoensis shows the presence of Chico beds on the Snoqualmie and other rivers at the western foot of the Cascade Range. The same beds are found at Lucia Island, just north of Puget Sound, and connect with the coal-bearing Nanaimo beds of Dawson upon the eastern side of Vancouver Island. Their correlation with the Chico of California is well established by fossils. (Diller.) In Vancouver and Queen Charlotte Islands, over the Lower Cretaceous, there are (1) the Middle Cretaceous, consisting of sandstones, shales, and conglomerates (which are 9700' thick in the latter), and (2) Upper, consisting of shales and sandstones (1500' thick in the latter). G. M. Dawson (1886). In Greenland, the plant beds of the vicinity of Disco Island, described by Heer, above the FromS group, or Lower Cretaceous, consist of (1) the Atane group of the Middle Cretaceous, corresponding nearly to the Colorado group, and (2) the Patoot group of the Upper, corresponding nearly to the Montana group. LIFE. 1. LOWER CRETACEOUS. PLANTS. The beds have afforded the earliest remains of the modern groupT of Angiosperms. They are associated with many species of Cycads, and the flora has therefore a transitional character between that of the Jurassic and the Upper Cretaceous. Eemains of more than 300 species have been described by Fontaine from the Potomac formation ( U. S. G. S., 4to, 1889). Among them are 75 Angiosperms, 22 Cycads, over 90 Conifers, and 140 Ferns. In 1894, 30 Cycad trunks were found in Maryland. Some of them occur in the Wealden (or Neocomian) of England, as Pecopteris Browniana, Aspidium Dunkeri, Sphenopteris Mantelli (Fig. 1353), and two Conifers of the genus Splienolepidium. Four of the nine species of Sequoia or Redwood (the genus to which the giant trees of California belong) agree with species described by Heer from the older Greenland Cretaceous. The Cycad trunks of Maryland are of the species Cycadeoidea Marylandica (Tysonia M. of Fontaine). No species is identical with any of those from Triassic beds. The Angiosperms include species of Ficus (Fig. 1351) or Ficophyllum, Sassafras, Aralia, Myrica, Platanus (or Plane tree), etc. ; and several of the genera, as those of Ficophyllum, Protceiphyllum, have compre- 832 HISTORICAL GEOLOGY. hensive features, indicative of early forms. The Cycad genus, Dioonites (Fig. 1350), occurs in the Neocomian of Europe (at Wernsdorf), and is very common in the Potomac beds. Fontaine says, in his conclusion, that the flora ranges from the Wealden through the Neocomian, and includes some later (Cenomanian) forms. All, or nearly all, the species are absent from the later Cretaceous beds of New Jersey. 1350-1353. 1353 PLANTS OP THE POTOMAC GROUP. CYCAD. Fig. 1350, portion of a frond of Dioonites Buchianus. ANGIO- 6PERM8. Fig. 1351, Ficus Virginiensis ; 1352, Protseiphyllum reniforme. FERN. Fig. 1853, Sphenopteris Mantelli. All from Fontaine. The plants of the Trinity beds of Texas are to a large extent identical, according to Fontaine, with those of the lower Potomac beds (1893). They include Cycad stumps named Oycadeoidea munita by Cragin. Cycadeoidea Jenneyana of L. F. Ward occurs in the form of stumps at the Black Hills, on MESOZOIC TIME CRETACEOUS. 833 the western border of South Dakota, in beds that are shown by Ward to be Lower Cretaceous, though formerly referred to the Dakota group. The flora of the Kootanie beds, in British America, described by Dawson, includes no Angiosperms ; but the identity of other species with some of those of the Potomac group is regarded as sufficient evidence of equivalency. Some of the kinds are here represented. Fig. 1354, Sequoia Smittiana of Heer, common in the Greenland beds; 1355, Salisburia Sibirica, a species described by Heer from the Lower Cretaceous of Greenland ; and 1356, the Cycad, Podozamites lanceolatus Lindley, a species that is found also in Siberia, Sweden, India, and China, and appeared first in the Jurassic. The same species occur in the Kootanie beds of Montana, as first observed by Newberry. Cretaceous plants from Cape Lisburne, Alaska, were referred by Lesquereux, in 1888, to the Neocomian. The number of species thus far described from the region is 60 (Knowlton). The Koine beds of Greenland afforded Heer species of Ferns, Cycads, Conifers, a few Endogens, and but one Angiosperm, Populus primceva. The plants of the Kootanie beds include, according to Dawson, besides those of Figs. 1354-1356, Dioonites borealis Dawson, Zamites Montana Daws., Z. acutipennis 1354-1366. 1354 1355 KOOTANIE PLANTS. CONIFERS Fig. 1354, Sequoia Smittiana ; 1355, Salisburia Sibirica. CYCAD. Fig. 1356, Podozamites lanceolatus. J. W. Dawson. Heer, Salisburia nana Daws., Baiera longifolia Heer, Glyptostrobus Groenlandicus Heer, Taxodium cuneatum Newberry. (Heer's species are all Greenland species.) From DANA'S MANUAL 53 834 HISTORICAL GEOLOGY. Queen Charlotte Islands he has announced Dioonites Columbianus Dawson. From the Kootanie beds of Montana at Great Falls, Newberry has described (1891) 25 species of plants, and among them, Zamites Montana, Z. acutipennis, Z. borealis Heer, Z. apertus Newberry, Podozamites nervosus Newb., Sequoia Smittiana Heer, S. gracilis Heer, 8. fieichenbachi Heer, and Sphenolepidium Virginicum Fontaine. The last two are also found in the Potomac group. From the Trinity group of Texas, Fontaine has identified some Neocomian species : as Dioonites Buchianus, D. Durikerianus, Abietites Linkii, and a species very near Sphenopteris Valdensis, besides several other species that occur in the Potomac group. 1357. KHIZOPOD. Patellina Texana. Koetner. 1358. ANIMALS. Marine fossils are confined almost solely to the beds of Texas and Mexico, and the Pacific Coast region; and these two regions widely differ in fauna. The former was apparently tropical, while the latter bears evidence of cooler waters, just as the Mexican Gulf and California seas now differ. At present this dif- ference (as shown on the isocrymal chart, page 47) is about 16 F., owing to the cold currents that descend the Pacific coast from the north; and it was probably 10 or 12 in Cretaceous times, when like species occurred on that coast from California to Alaska. Texas. The Comanche beds are largely made of the minute shells of Rhizopods, and also contain the larger Nummulite-like fossil, the Patellina (Orbitulites) Texana (Fig. 1357). Echi- noderms are represented by species of Enallaster (Fig. 1358) , Pseudodiadema, Hemi- aster, Cidaris, etc. ; Brachio- pods, by species of Terebra- tula. Lamellibranchs occur of the genera Gryphcea (Fig. 1359), Exogyra (Fig. 1360), Lima, Inoceramus, which are very common. Some speci- mens of Exogyra ponderosa in Texas are nine inches long, and the shell four inches thick at middle. Two species of genera related to the modern Chama, peculiar to the Cretaceous, are Radiolites Texanus (Fig. 1361, 1361 a), reduced from a length of 4J- inches, and Requienia (Caprina) Texana (Fig. 1362). The genus Nerinea (Fig. 1363) is also characteristic of the Cretaceous. Of the fossils of the Shasta group, California, the Aucellce are especially characteristic. The forms vary much, but all are referred to one species named by Gabb, A. Piochii. Fig. 1364 represents a common form of the shell, and Fig. 1365, the smaller valve of a specimen. Another specimen figured has a height of more than two inches, while but little wider than Ecu INODEKM. Enallaster Texanus, upper and under surface. Koemer. MESOZOIC TIME CRETACEOUS. 835 Fig. 1365. The shells are in great profusion in many localities, and are often associated with Belemnites appressus. Fig. 1366 is from a small shell from 1361 a 1359-1363. 1360 LAMELLIBRANCHS. Fig. 1359, Gryphaea Pitcher! of Morton; 1360, Exogyra arietina ; 1361, Radiolites Texanus, without upper valve (x $) ; 1361 a, the lid-like upper valve ; 1362, Kequienia Texana. GASTROPOD. Fig. 1363, Nerinea Texana. All from Roemer. 1364-1366. 1364 1365 1366 MOLLUSK. Figs. 1364-1366, Aucella Piochii. Gabb. Mt. Diablo, where they are rare. The shells fail entirely, or very nearly so, of the radiating striae which characterize the Jurassic Aucella of Mariposa (page 759). 836 HISTORICAL GEOLOGY. Vertebrates. Some scales of Ctenoid fishes have been found in the Potomac beds. But the Vertebrates of special interest are the large Reptiles : a species related to the 1367-1368. 1367 1368 DINOSAURS. Fig. 1367, Vertebra of Pleurocoelus nanus ; 1368, tooth of Priconodon crassus. From Marsh. Morosaurus, the Astrodon Johnstonii of Leidy (1865); and the other Dino- saurs Pleurocoelus nanus, P. altus, Priconodon cras- sus, Allosaurus (?) medius, and Coelurus gracilis, de- scribed by Marsh (1888). Fig. 1367 represents a side view of one of the dorsal vertebrae of Pleu- rocoelus nanus, and 1368, an inside view of a tooth of Priconodon crassus. On account of the Jurassic features of the Reptiles, the Potomac group has been referred by Marsh to the Upper Jurassic. From the Lower Cretaceous of Texas and its continuation into Oklahoma (formerly Indian Territory) five species of Pycnodont Fishes have been described by Cope : Mesodon diastematicus, M. Dumblei, and two species of Uranoplosus and one of Cododus. Characteristic Species. The fauna of Texas (and the country beyond to Mexico) has special interest, because the region is the only one of the Lower Cretaceous in North America abounding in marine fossils. The characteristic species are as follows, according to Hill : 1. Trinity group. The Glen Hose beds have afforded: Ostrea Franklini Coquand, Modiola Branneri Hill, Pecten Stantoni Hill, Eequienia Texana, Barbatia parva Missouri- ensis, Isocardia medialis Conrad, Natica pedernalis Roamer, Nerinea Austinensis Roemer; also, Crocodiles, Dinosaurs, Chelonians, and Fishes not yet studied. A bed of chalk is composed of the Rhizopod Patellina (Orbitulites) Texana R. (Fig. 1357). 2. Fredericksburg group. The prominent fossils of its several subdivisions are the following: (1) The Gryphcea rock and Walnut sands: Exogyra Texana R. ( = E. flabellata Goldfuss) ; and, higher up, a bed made up of Gryphcea Pitcheri (the small form figured by Conrad). (2) The Comanche Peak chalk: Pseudodiadema Texanum R., Enallaster Texanus R., Exogyra Texana, Gryphcea Pitcheri Conrad (not Marcou), Janira occidentalis Con., Protocardium Hillanum Sowerby, Nerinea acus R., Ammonites (Buchiceras) pedernalis R. (3) The Caprina limestone, also called the " Hippurite " limestone: Nerinea Austinensis R., N. cultrispira R., N. subula R., Cerithium Austinense R., Trochus Texanus R., Solatium planorbis R., Monopleura marcida White, M. pinguiscula White, Eequienia patagiata White, Ichthyosarcolithes (Caprina} anguis R., I. (?) crassifibra R., /. ( ?) planatus Con., Eadiolites (Sphcerulites) Texanus R. 3. Washita group. (1) The Preston beds, Schlcenbachia clays, including lime- stone flags, Gryphcea forniculata White ( = G. Pitcheri Marcou), and the Ammonite Schlcenbachia Peruviana v. Buch. ; the limestone is the building material of old Fort Washita. (2) The Duck Creek chalk, many Ammonoids, among them Pachydiscus Brazoensis Shum., Schlcenbachia Belknapi Marcou, and Hamites Fremonti Marcou ; with MESOZOIC TIME CKETACEOUS. 837 Isocardia Washita Marcou, Inoceramus, Terebratula Choctawensis Shum. (3) The Fort Worth or Washita limestone : with Terebratula Wacoensis R., Cidaris Texana R., Leiocidaris hemigranosa Shum., Holectypus planatus R., Epiaster elegans Shum. , Holaster simplex Shum., Ottrea carinata Lam., Exogyra sinuata Marcou, Gryphcea Pitcheri Morton, Janira Wrightii Shum., Plicatula placunea d'Orb., Pleurotomaria Austinensis Shum., Lima Kimballi Gabb, Nautilus elegans Shum., Ammonites (Mortoniceras) Leonensis Con., Turrilites Brazoensis R. (4) The Denison Beds of clays and limestone: having at base Exogyra arietina R., Ostrea quadruplicata Shum., Gryphcea Pitcheri R. (not Morton, which is G. mucronata Gabb), the Ammonites Buchiceras inceqiiiplicatnrn Shum., Hoplites Deshayesi Leym., and many other species. Turbinolia Texana is abundant in the western exposures of the Denison beds, and the Rhizopod, Nodosaria Texana Con., occurs throughout them. Hill concludes from the fossils that the Trinity group is closely related in age to the Wealden of Europe, and the Washita to the Lower Greensand or Gault. The Horsetown beds of California have afforded many species, described chiefly by Gabb andTrask. Among them are: Pecten operculiformis, Pleuromya Icevigata, Nemodon Van- couverensis, Nerita deformis, Nerinea dispar, Neithea grandicostata, Lima Shastaensis, and the Ammonites Desmoceras Breweri, Lytoceras Batcsii, Pachydiscus Whitneyi, Olcoste- phanus Traskii, Ancyloceras Remondi, etc. The first three Ammonites occur in the Queen Charlotte group, according to Whiteaves. The Knoxville beds are characterized, according to the latest researches of Hyatt, Stanton, and Diller, by its Aucella, Ammonites, and a few other fossils, which show close relations to the Horsetown beds and a wide divergence from the Mariposa beds. The Potomac beds have afforded a few rare marine shells. Whitfield mentions Astarte veta, Ambonicardia Cookii, Corbicula emacerata, C. annosa (Astarte annosa Conrad), and Gnathodon tenuides, besides 6 species of Unto and Anodonta. 2. UPPER CRETACEOUS. PLANTS. In the Upper Cretaceous, leaves of Cycads are comparatively rare, while those of Angiosperms are of great variety ; and to these are added the leaves or fronds of Palms. Some of the prominent kinds in the new flora were species of Sassafras, Laurus, Liriodendron (Tulip Tree). Magnolia, Aralia, Cinnamomum, Sequoia, the Poplar, Willow, Maple, Birch, Chestnut, Alder, Beech, Elm, etc. A leaf of a Palm (Sabal) from Vancouver Island is described by Newberry as 8 to 10 feet in diameter. Dawson gives an interesting review of the Sequoias in his Geological History of Plants a genus of many species then, but now of only 2, and these exclusively North American. The leaves of Angiosperms, here figured, are all from the Dakota beds, or their probable equivalent, on the Atlantic border, the Karitan clays of New Jersey, Martha's Vineyard, and Long Island. Fig. 1369 represents a leaf of Sassafras Cretaceum Newb., of the Dakota group ; 1370, the leaf of a Tulip Tree, Liriodendron Meekii Heer, from Greenland (Atane group) and the Dakota ; 1371, L. simplex Newb., from the Amboy clays of New Jersey, Long Island, and Gay Head, Martha's Vineyard, the figure from a leaf of the latter locality ; 1372, an Andromeda, from Gay Head, a kind found also in Greenland and the Dakota group ; 1373, a Myrsine of Gay Head, and likewise a Greenland species; 1374, a Willow, Salix Meekii Newb., of the Dakota; HISTORICAL GEOLOGY. and 1375, Eucalyptus Geinitzi Heer, from Gay Head, also occurring in Green- land, Bohemia, and Moravia, a genus now mostly confined to Australia. Fig. 1376 represents a nut of the Eucalyptus. D. White, the describer of the Gay Head plants (1890), states that these nuts contain in their furrows an amber-like resin, and suggests that the Eucalyptus Tree may have been the source of the "amber" of the Gay Head and New Jersey regions. 1372 1373 1369-1376. 1371 ANGIOSPERMS. Fig. 1869, Sassafras Cretaceum ; 13TO, Liriodendron Meekii ; 1371, L. simplex ; 1372, Andromeda Parlatorii ; 1373, Myrsine borealis ; 1874, Salix Meekii ; 1375, Eucalyptus Geinitzi ; 1876, nut of Eucalyptus. Figs. 1369, 1370, 1374, Newberry ; others, D. White. Coccoliths, calcareous disks less than a hundredth of an inch in diameter (page 437), which are now common over the bottom of the deep oceans, con- tributed to the Cretaceous limestones, and are abundant in the Cretaceous of the east slope of the Rocky Mountains. In the clays of Gay Head, on Martha's Vineyard, the most eastern Cretaceous region of the continent, D. White identified Sphenopteris Grevillioides Heer, of the Rome beds, Greenland ; Sequoia ambigua Heer, Kom6 and the Lower AtanS (or Middle Cretaceous) ; Andromeda Parlatorii, Lower Atane ; and also a Sapindus, near S. Morrisoni of Lesque- reux, a Dakota and Greenland species. MESOZOIC TIME CRETACEOUS. 839 A report by J. S. Newberry, on the plants of the Raritan group of the Atlantic border, nearly ready for publication at the time of his death in 1892, has not yet appeared (1894). A few Long Island species have been described and figured by A. Hollick (1892-93). They were from the clays on the north side of the island between Eaton's Neck and Glen Cove. An account of the plants of the Dakota group is contained in Lesquereux's quarto reports one volume published in connection with the reports of the Hayden Expedition, and another posthumous volume, edited by F. H. Knowlton, published as vol. xvii. of the Memoirs of the U. S. Geological Survey (1893). The flora, so far as now known, in- cludes 429 Angiosperms, 8 Endogens, 15 Conifers, 12 Cycads, and 6 Ferns ; in all 470 species. As Knowlton states, the proportion of Cycads is nearly the same as in the AtanS group of Greenland described, by Heer, while the Angiosperms make 91 per cent of the whole and in the AtanS group 72 per cent ; and a fourteenth of the whole are identical with Greenland species. The spirally marked fruit of a Chara, C. Stantoni, has been found by Knowlton in the Bear River beds. The Laramie plants also were described by Lesquereux in one of the quarto volumes of the Hayden Expedition reports. But it is found that there is some uncertainty with regard to localities, and the subject is undergoing revision. They include no Cycads. The following lists of characteristic species of the Laramie and Denver groups are from F. H. Knowlton : Fossil plants characteristic of the Lower Laramie : Musophyllum complicatum, Flabel- laria eocenica, Ficus lanceolata, Ficus latifolia, Quercus angustiloba, Sterculia modesta, Anona robusta, Dombeyopsis squarrosa, Nelumbium tenuifolium, Bhamnus salicifolius, Cornus suborbifera. Fossil plants characteristic of the Denver group : Osmunda affinis, Asplenium erosum (Pteris erosa Lx.), Aspidium Lakesii, Woodwardia latiloba, Oreodoxites plicatus, Ficus occidentalis, F. spectabilis, Populus Nebrascensis (varieties), Fraxinus eocenica, Zizyphus fibrillosus, Ehamnus Goldianus^Platanus Eaynoldsii, Viburnum Goldianum. Fossil plants common to both the Lower Laramie and Denver groups : Ficus plani- costata, Dombeyopsis obtusa, Paliurus zizyphoides, Artocarpus Lessigiana. The plants of the Livingston beds, referred by Weed and Knowlton to the Denver horizon, are the following (U. S. G. S. Bulletin, No. 105, 1893). They are stated to be, by Weed, from the lower 300' of the beds. Those species that occur also in the Lower Laramie beds are designated by Lar. ; those in the Denver group of the Denver region, by the letter D ; and those that are known from the Miocene Tertiary, by the letter M : Abietites dubius Lesquereux Lar. Sequoia Reichenbachi Geinitz Lar. Taxodium distichum Miocenum Heer. Ginkgo adiantoides Ung. Phragmites Alaskanus Heer. Caulinites sparganioides Lx Lar. Populus mutabilis ovalis Heer Lar. " Isevigata Lx D. Salix angusta Al. Br Lar., M. Quercus castanopsis Newb. Godeti ? Heer. " Ellisiana Lx Lar. Juglans rugosa Lx Lar., D., M. " denticulata Lx D., M. " rhamnoides Lx Lar., D. Platanus Guillelmse Goppert. . .Lar., D. M. ? " aceroides Goppert D., M. Ficus auriculata Lx D. ? " tiluefolia (Al. Br.) Heer. . . Lar., D. " planicostata Lx Lar., D. Cinnamomum Scheuchzeri ? Heer. " ellipticum Knowlton. Litsaea Weediana Knowlton. Laurus socialis Lx type from Lar. Fraxinus denticulata Heer Lar.? Andromeda affinis Lx. ? Nyssa lanceolata Lx D. Rhamnus rectinervis Lar., D. " salicifolius ? Lx Lar. Celastrinites laevigatus Lx. 840 HISTORICAL GEOLOGY. 1379 1377-1379. 1377 The fossil plants of the Dun vegan group of northern Canada (north of 55 N.) con- tain, according to Dawson, species of Magnolia, Laurus, Ficus, Quercus, Fagus, Setula, Sequoia, and Cycads, and are referred to the age of the Niobrara. The plant-bearing Mill Creek beds overlying the Lower Cretaceous of the Queen Charlotte Islands are made Dakota in age ; and the Coal-measures of Vancouver Island are, on the same authority, of the age of the Montana group. Dawson refers to this time Heer's Patoot flora of Greenland. He compares this flora with that of Georgia, and from the general resemblance in genera infers that the temperature of the region may have been, like that of Georgia, about 65 F. The Laramie flora, he observes, is most remarkable for its Conifers, Taxites, Sequoia, Thuia, etc., and for the great development of the genus Platanus ; also for con- taining some modern species of Ferns, as Onoclea sensibilis, Davallia tenuifolia. References to all papers and reports on fossil plants published before 1884 will be found in Ward's Sketch of Palseobotany, U. S. G. /S. Ann. Hep., vol. v. ANIMALS. Invertebrates. The shells of Rhizopods, or Foraminifers, are abundant in many of the beds in New Jersey, and still more so in those of Texas. Sponges are thus far rare fossils in the beds. Corals are not numerous. One from the Ripley beds of Texas, described and figured by C. A. White, is represented in Fig. 1377. No coral reefs have been reported ; but they may possibly exist underneath the Tertiary of some part of the Gulf or Atlantic border. Echinoids occur of the genera Cidaris, Salenia, Cassidulus, Holaster, Hemiaster, and others. Less than 35 Upper Creta- ceous species are known from all North America, while Great Britain has afforded nearly 150. Brachiopods are few in species. The two here figured, Terebratella plicata (Fig. 1378), and Terebratula Harlani (Fig. 1379) of Morton, are quite common in New Jersey. Meek described only one Lingula, L. nltida, from the Upper Cretaceous of the Continental Interior, and this was from the Fox Hills group. The contrast in species between the closing period of the Mesozoic and that of the Paleo- zoic is in no tribe more marked. Of the characteristic Lamellibranchs there are, in the 0} 7 ster family, the genera Ostrea (Figs. 1380, 1381), Gryphcea (Figs. 1384, 1385), and Exogyra (Fig. 1383) ; and in the Avicula family, Inoceramus, L labiatus (Fig. 1386) being very common. The Rudistes, one Neocomian species of which is figured on page 835 (Fig. 1361), are very rare fossils in America in the Upper Cretaceous. Fig. 1387 represents one species described by C. A. White from the Wallala section of the Chico beds of California. Other Gastropods of modern forms are represented in Figs. 1388-1392. 1378 COBAL. Fig. 1377, Hindeastraea discoidea. BRACIIIO- PODS. Fig. 1378, Terebratella plicata ; 1379, Tere- bratula Harlani. Fig. 1377, C. A. White; 1378, 1379, Morton. MESOZOIC TIME CRETACEOUS. 841 Cephalopods of the tribes of Belemnites and Ammonoids are of many species. One of the most common of the Belemnites, common to New Jersey, 1380 1382 1380-1386. 1384 LAMELLIBRANCHS. Fig. 1380, Ostrea congesta; 1381, Ostrea larva ; 1382, Inoceramus dimidius ; 1383, Exogyra costata ; 1384, Gryphaea vesicularis ; 1385, G. Pitcher! ; 1386, Inocerainus labiatus (formerly problematicus). Fig. 1380, 1382, Stanton ; 1381, D'Orbigny ; 1383-1385, Meek ; 1386, Kcemer. 138 1387-1392. 1392a 13926 LAMELLIBRANCH. Fig. 1387, Coralliochama Orcutti (x |). GASTROPODS. Fig. 13S8, Pyrifusus Newberryi ; 13S9, Fasciolaria buccinoides ; 1390, Anchura (Drepanocheilus) Americana; 1391, Margarita Nebrascensis ; 1392 a,6, Eulla speciosa. Fig. 1387, C. A. White ; 1388-1392, Meek. Texas, and the Upper Missouri, is represented in Fig. 1393. Fig. 1394 represents the Ammonite, Placenticeras placenta of Dekay ; 1394 a, the same in side view ; and 1394 6 shows the flexures in the partition at the sutures ; 842 HISTORICAL GEOLOGY. specimens of this species have been found measuring more than two feet in diameter. Among the more or less uncoiled Arnmonoids there are : Fig. 1395, the Scaphites, S. Conradi, from the Fox Hills group, which is sometimes six feet CEPHALOPODS. Fig. 1393, Belemnitella Americana; 1394, o, 6, Placenticeras (Ammonites) placenta; 1395, Scaphites Conradi ; 1896, S. larvaeformis ; 1397, 1397 a, Baculites ovatus ; 1398, young stage of B. com- pressus ; 1898 a, same, with outer layer of shell removed, showing sutures ; 1399, section of B. compressus, reduced ; 1400, Nautilus Dekayi. Figs. 1393-1397, 1399, 1400, Meek ; 1398, 1898 a, A. P. Brown. MESOZOIC TIME CKETACEOTJS. 843 long ; and 1396, S. larvceformis, another, showing more decidedly the imper- fectly coiled condition, from the Fort Benton group. Fig. 1397 is an Amino- noid in which the form is straight, and hence the name Baculites, from the Latin baculum, a walking-stick. The length of this Baculite is over a foot, and the diameter 2^ inches ; other associated species are more than a yard long. Another species, common in New Jersey, is the B. compressus Say, and Fig. 1399 is a section of it. A young stage of it is represented, enlarged, in Figs. 1398, a, by A. P. Brown (1891) ; the specimens were from the Black Hills, S. D. ; they show that the animal in the young stage has a perfectly coiled shell. Others of these partly uncoiled kinds are represented on page 862. Fig. 1400 is a Nautilus from the Lower Greensand, New Jersey. Vertebrates. 1. Fishes. In addition to Selachians and Ganoids there were Teleosts, or Osseous Fishes, the tribe which includes the larger part of modern fishes, and nearly all edible species. The Cestraciont Sharks still continue ; and the bony pavement .pieces of the mouth are not rare fossils. Two views of one from New Jersey are given in Figs. 1406, 1406 a. 1401-1406. 1406 1403 1401 SQUALODONT SELACHIANS. Fig. 1401, Otodus appendiculatus ; 1402 a, 6, Lamna Texana; 1403, Corax hetero- don ; 1404, Otodus appendiculatus ; 1405, Oxyrhina Mantelli. CESTEACIONT SELACHIAN. Figs. 1406, 1406 o, Ptychodus Mortoni. Fig. 1401, Gibbes ; 1402-1405, Rcemer ; 1406, Morton. Many of the Sharks were of the modern tribe of Squalodonts distinguished by the sharp cutting edges of the teeth, and other peculiarities. One kind is represented in Figs. 1401 and 1404 of the genus Otodus, the latter from Texas; 1403, tooth of a Corax; 1405, of an Oxyrhina; 1402 a, 6, of Lamna Texana. The Teleosts of the Middle and Upper Cretaceous of North America in- clude species of the Mullet family, represented by Beryx insculptus Cope, from New Jersey ; the Sphyrenids of several large species described by Cope, of the genera Pachyrhizodus, Empo, and others, from Kansas ; the Siluroids, powerful carnivorous fishes, called Saurodonts by Cope, one of which, Por- theus molossus Cope, from Kansas, had the vertical diameter of the head 844 HISTORICAL GEOLOGY. nearly two feet. They appear to have been among the most formidable of all Teleosts. Saurocephalus lanciformis Harlan (Saurodon lanciformis Hays, 1830), from the " Upper Missouri region," is one of the group. 1407 Restoration, showing the probable form of Portheus, Cope. 2. Reptiles. The Reptiles included species of enormous size, yielding to few if any of the Jurassic period. Besides long-necked Sea-Saurians, related to 1408. Restoration of Claosaurus annectens (x^). Marsh. the Plesiosaurs, and huge carnivorous and herbivorous Dinosaurs, related to the older kinds, there were other Dinosaurs equally huge, having horns with horn-cores, like cattle, but with a third horn on the nose ; Pterosaurs, 20 feet MESOZOIC TIME CRETACEOUS. 845 and upward in span of wings ; and, as a new feature, great Sea-serpents, the Mosasaurids, having a length of 10 to 80 feet. Plesiosaurids of the genus Cimoliosaurus of Leidy (1865) have been found in New Jersey, Alabama, and Mississippi, and others, of the genus Elasmo- saurus of Cope, in the Continental Interior. The E. platyurus, a carnivorous species, 45 to 50 feet in length, had a neck 22 feet long, containing over 60 vertebrae. The Herbivorous Dinosaurs include species of widely diverse forms and great magnitude. The first discovered is the Hadrosaurus Fonlkii of Leidy (1858), a species about 28 feet long, having many of the characters of the Iguanodon of Great Britain. A related species, equally large, is the Claosaurus annectens of Marsh (1890), from the Ceratops beds of eastern Wyoming, of which a restoration by the describer is here given (Fig. 1408). It is an excellent example of these three-toed Ornithopod Reptiles, with their short fore feet, and very massive tail, the latter, one of the three supports of the heavy body when erecting itself for brousing. A side view of the skull is shown in Fig. 1409. The teeth are confined to the maxillary 1409-1411. 1409 1411 CLAOSAUBUS ANNECTENB. Fig. 1409, the skull, side view (x T V) ; 141. to P view (x a, front view ; 6, side view(x ). From Marsh. ; 1411 a, 6, series of teeth : and dentary bones, and are in great numbers ; they are arranged in vertical series, and Fig. 1411 is an outer view of one of the series, in which the number of teeth is five. The number of teeth in the series is largest over the middle of the jaw, and is sometimes six or more. Fig. 1410 is an upper view of the skull. At b is the brain cavity, which, as Marsh states, is very small in proportion to the head. 846 HISTORICAL GEOLOGY. Another species, more closely like Hadrosaurus, is the Diclonius mirabilis of Cope (1883; Trachodon mirabilis of Leidy, 1868), from the Laramie beds of Dakota. The length stated is 38 feet, and that of the head, 3 feet. 1412. DINOSAUR. Triceratops prorsus (x ^j). Marsh. Widely different were the Herbivorous Dinosaurs of the family Ceratop- sidae of Marsh, species of great magnitude, having the horns of cattle with 1414 1413-1415. 1415 DINOSAUBS. Fig. 1413, Tooth of Triceratops prorsus, showing the two prongs (natural size) ; 1414, skull of T. serratus (x jfo ?) ; 1415, skull of Torosaurus gladius ( 3 V)- Marsh. MESOZOIC TIME CRETACEOUS. 847 1416. the beaked mouth of a Turtle, or rather of the Khynchocephs of the Trias. They are from the same Laramie beds in Wyoming that afforded the Clao- saurus, and occur also in the Denver beds, near Denver, Col. (where the first specimen was found), at Black Butte, Wyoming, and in the Judith River beds, Montana. The restoration by Marsh (Fig. 1412), one sixtieth the natural size, shows the general character of the skeleton of these strange but stupid inhabitants of the waning Mesozoic. The broad cranium (over eight feet long in one species) projects far over the neck, like the posterior flap of some forms of helmet, and sometimes has a degree of decoration in its pointed posterior margin. The teeth had two prongs (Fig. 1413), a Mammalian feature not known in other Reptiles. The skull of another species of the genus is shown in Fig. 1414 ; and of a third, but of a distinct genus, Torosaurus, in Fig. 1415. J. B. Hatcher, who procured many of the bones described by Marsh, gives evidence (1893) that the great Dinosaurs lived in the region where they died ; and he speaks of one skeleton of Claosaurus annectens Marsh (Fig. 1408), as found in a partially erect condition, the limbs extended, the ribs in natural position about the abdominal and thoracic cavities, and every bone in its natural place, showing that the animal had been mired in the quicksands. Some of the Ceratopsid skulls, although seven to eight feet long, make the centers of sandstone concretions, weighing many tons. Other genera of Ceratopsids described by Cope are Agathaumas, Monoclonius, and Polyo- nax, severally from Wyoming, Montana, and Colorado. Agathaumas sylvestris is from the Laramie of Black Butte station in southern Wyoming. Carnivorous Dinosaurs were represented by a number of species. Loelaps aquilunguis of Cope (1869), from the Upper Greensand, New Jersey, is about 24 feet long; it probably could stand nearly erect. L. incrassatus is reported by him from Montana, and also from the Laramie beds of Red Deer River in British America. The Ornithomimus of Marsh is a small species from the Laramie Ceratops beds of Wyoming, remark- ably bird-like in its skeleton, as illustrated in the figure (Fig. 1416). It probably could stand erect like a bird. The Mosasaurids, or Sea-serpents, of the era, Pythonomorpks of Cope (after the genus Pytho), were eminently characteristic of the Upper Cretaceous. Previous to the American discoveries of their remains, knowledge of them was confined DINOSAUR. Fig. 1416, Ornithomi- mus velox, 2d, 3d, and 4th meta- tarsals, natural size ; 1416 a, phalanges of 2d digit. Marsh. 848 HISTORICAL GEOLOGY. almost solely to a skull found in the uppermost Cretaceous beds of Belgium, on the river Meuse, 1785, whence was derived the name Mosasaurus. The first American species was a tooth in a fragment of a jaw, found at Mon- mouth, N. J., and figured in S. L. Mitchill's Geology of North America, 1818, described by Dekay in 1830, and named Mosasaurus major by him in 1841. Previously it had been named M. Dekay i by Bronn (1838). The tooth, according to Dekay, was 1-06 inches long and 1-02 and 1-33 broad at base. Through the discoveries since made, the number of American species described is near 50 ; and their remains have come from the borders of the Atlantic and the Mexican Gulf, and from the Interior Continental seas in Kansas, Dakota, Colorado, and beyond. Kansas is credited with 25 or more Mosasaurids from the Niobrara beds. The species are related, like true Snakes, to the Lacertians ; but they had paddles, and a skulling tail which was nearly half the length of the body, as shown in the restoration of Edestosaurus (Clidastes) velox of Marsh, by S. W. Williston, in the following figure. The Clidastes iguanavus of Cope is from 1417. Bestoration of Edestosaurus (Clidastes) velox (x ^). Williston the Lower Greensand, New Jersey, and C. propython of Cope, from the Rotten Limestone in Alabama. Baptosaurus platyspondylus and B. fraternus, both of Marsh, are from the Upper Greensand of New Jersey. One of the fore paddles of Lestosaurus of Marsh is represented, much reduced, in Fig. 1420. Fig. 1418 represents the tooth of Mosasaurus princeps of Marsh, from New Jersey, and 1419, the head extremity of one of the Mosasaurids, showing the bases of four teeth. An anomaly in Mosasaurus is the existence of an articulation for lateral motion in either ramus of the lower jaw (at a in Fig. 1421), where there is in all other Eeptiles a suture only ; a fact first recognized by Cope. Besides, the extremities of the two rami were free, so that they could serve like a pair of arms in the process of swallowing whole a large animal. True Snakes are rare species in the Mesozoic. The Coniophis precedens of Marsh, the only one known in this country, occurs in the same beds with the remains of the Ceratopsidae in eastern Wyoming. Crocodilians were represented by the Thoracosaurus of Leidy (the New Jersey Gauial, or Gavialis Neocesariensis of De Kay, 1833), Holops pneu- maticus and Gavialis fraterculus, of Cope, from New Jersey, and other species having the vertebrae concavo-convex, as in true Crocodiles. The older type, with biconcave vertebrae, also was represented; and Hyposaurus Rogersi Owen (1849) from New Jersey, and H. Webbii Cope from Kansas are exam- MESOZOIC TIME CRETACEOUS. 849 pies. Two Lizards, Chamops segnis Marsh, and Iguanavus teres Marsh (1892), occur in Wyoming in the beds affording the Ceratops remains. 1418 1418-1421. 1419 1420 MOSASAITRIDS. Fig. 1418, tooth of Mosasaurus princeps (x|); 1419, snout of Tylosaurus micromus, showing bases of four teeth (x); 1420, right paddle of Lestosaurus simus (x^j); 1421, restored jaw of Edestosaurus dispar (xj). All from Marsh. The Turtles (or Chelonians of the American Cretaceous) were of 50 or more species ; and one, Protostega gigas of Cope (tAtlantochelys Mortoni Agas- 1422. Fig. 1422, Pteranodon longiceps, head (x) : a, upper view ; 6, side view. Marsh. siz), from the Niobrara beds of western Kansas, had a head two feet long, and a total length of nearly 13 feet. Desmatochelys Lowii of Williston is DANA'S MANUAL 54 850 HISTORICAL GEOLOGY. from the Benton group in Kansas. Species of Compsemys occur in the Laramie beds at Judith River and elsewhere, and also of Trionyx and Plasto- menus. Adocus beatus Leidy, A. punctatus Marsh, A. agilis Cope, are New Jersey species. 1423-1429. 1424 1423 14-25 BIRD. Fig. 1423, Hesperornis recalls, skeleton (xj) ; 1424, left lower jaw, top view (x$) ; 1425, same, side view ; 1426, tooth (xf); 1427, 20th dorsal vertebra, side view (xf); 1428, same, front view; 1429, pelvis (x>; a, acetabulum ; il, ilium ; is, ischium ; p, pubis ; p', post-pubis. Marsh. MESOZOIC TIME CRETACEOUS. 851 Pterosaurs of several species have been discovered in western Kansas, in the "Middle " Cretaceous, the first by Marsh in 1870; two had an expanse of wings of 20 to 25 feet, and another of 18 feet. They are toothless, unlike the- foreign species, and are named by Marsh Pteranodonts ; anodont from the 1430, 1431. 1430 1431 a 14316 Bnu>. Fig. 1480, Ichthyornis victor, skeleton, restored (xj); 1431 a, 6, c, d, I. dispar: a, left lower jaw, side view (xf) ; 6, same, top view ; c, cervical vertebra, side view (xf) ; d, same, front view. Marsh. 852 HISTORICAL GEOLOGY. Greek, signifying tuithout teeth. The skull and slender bird-like jaws of Pteranodon longiceps Marsh are shown in Fig. 1422 b, and an upper view in Fig. 1422 a. The fore limbs (wings) are enormous, the hind limbs very small. These animals, as Marsh observes, have several vertebrae anchylosed to act as a sacrum to the pectoral arch (like the sacrum in the pelvic arch), for the support of the powerful wings. The skull alone of P. ingens of Marsh is about four feet long, and that of P. longiceps over three feet. The abundance of their remains in the Kansas beds appears to show that these great bird-billed Pterosaurs frequented the borders of the Cretaceous sea as its Kingfishers. 3. Birds. The Cretaceous Birds, in part, had teeth (like the Jurassic of Solenhofen), as first reported by Marsh from Kansas specimens. One of the species, the Hesperornis regalis of Marsh, five to six feet in height, is repre- sented in Fig. 1423 (reduced to i) from an essentially complete skeleton. The figures also illustrate, besides the skeleton, one of the teeth, the jaw in two positions, a dorsal vertebra, and the pelvis. The teeth are fixed in a groove, as in many Reptiles. This large bird had short wings, ostrich-like, with many of the characteristics, of a Loon, one of the Divers. Another Kansas bird of different type is the Ichthyornis victor of Marsh, a small bird, with good wings. The fish-like feature to which the name alludes is the biconcave form of the vertebrae. But, with this low-grade feature, it has the teeth in sockets. In the restored skeleton (half the natural size), Fig. 1430, the bones actually found are those of the shaded part. Apatornis of Marsh is a related bird. Marsh has described, also, species of two other genera related to Hesperornis; namely, Baptornis and Coniornis, the latter from the Fox Hills group, Montana. All the Cretaceous birds have the fore limb greatly modified for wing purposes, bird-like ; but in the Hesperornis it has passed beyond this and become rudimentary, as in the Ostrich. This is in striking contrast with the earlier Jurassic birds, in which the fore limb is more completely and normally a leg than a wing. The toothless birds (or those not yet proved to be toothed) of the Cretaceous beds of New Jersey were related to the Cormorants and Waders. 4. Mammals. The Mammals of the Cretaceous thus far discovered are probably all Marsupial or Monotreme, like those of the Jurassic period. The remains are mainly teeth, with a few broken jaws and limbs. The earliest described is the Meniscoessus conquistus of Cope, discovered by J. L. Wortman in the Laramie of Dakota (1882, 1884). Many kinds have been described by Marsh (1889-1892). The following figures are from his plates of 1892. The figures 1432-1438 are supposed by Marsh to represent teeth and por- tions of jaws of Marsupials, and the remainder probably of Monotremes. The teeth of the genus Tripriodon have some resemblance to the tooth of the Meniscoessus figured by Cope, and have been referred by Osborn to that species. MESOZOIC TIME CRETACEOUS. 853 1432-1443. b c 1432 a 1438 a 1434 a 14346 MONOTREME AND MAK8TJPIAL MAMMALS. Fig. 1432 a, Cimolestes incisus, left lower jaw (x 2) ; 1432 6, c, lower molar (x 3) ; 1432 d, e, id., canine, natural size ; 1433 a, 6, c, Didelphops comptus, upper molar (x 3) ; 1434 a, D. vorax, two upper molars (x 2) ; 1434 6, Didelphops, milk tooth (x 3) ; 1435 a, 6, D. ferox, views of right lower jaw ; 1436 a, Batodon tenuis, lower jaw (x 3) ; 1436 6, id., with last two molars (x 2) ; 1436 c, d, e, id., upper molar (x 3) ; 1437 a, b. c, Stagodon validus, premolar (x 2) ; 1437 d, id., left lower canine ; 1437 e, id., part of lower jaw, sho%ving canine and two molars, natural size ; 1438 a, 6, Stagodon tumidus, upper premolar (x 2) ; 1439 o, 6, Oracodon conulus, upper premolar (x 3) ; 1440, Dipriodon lunatus, natural size ; 1441 a, 6, Halodon sculptus, right lower, fourth premolar (x 2) ; 1441 c, id., left lower incisor ; 1442, Tripriodon ccelatus, right upper molar (x 2) ; 1443, T. caperatus, right upper molar Cx 2). Marsh, 1892. 854 HISTORICAL GEOLOGY. Characteristic Species. NEW JERSEY. The following lists of New Jersey species are from the reports of R. P. Whitfield, from whom have been taken also the chief part of the references to occurrence in the Ripley group of Alabama (indicated by R.), and in the Upper Cretaceous beds ol Texas (indicated by T.) ; the other references being from T. W. Stanton : Lower Greensand. Catopygus pusillus, Cassidulus florealis, Terebratula Harlani, Terebratella plicata, Ostrea larva (R., T.), Exogyra costata (R.,T.), Gryphcea vesicularis (R., T.), Pecten venustus, Amusium simplicum (R.)? Neithea quinquecostata (R.)i Radula acutilineata (R.) Spondylus gregalis, Germlliopsis ensiformis (R., T.), Inoceramus Crispii var. Barabini (R.,T.), Idonearca vulgaris (R., T.), Trigonia Mortoni, T. Eufaulensis (R.), Cardium (Criocardium) dumosum (R., T.), C. Eufaulense (R., T.), Crassatella vadosa (R.), Veniella Conradi (R., T.), F. trapezoidea (R.), Anchura abrupta (R., T.), Cypri- meria depressa (R., T.), Gyrodes crenatus (R., T.), G. petrosus (R., T.), Veleda lintea (R., T.), Leptosolen biplicata (R., T.), Scalaria Sillimani, 8. Hercules, Turritella com- pacta, T. vertebroides (R., T.), Ligumen planulatum (R., T.), Nautilus Dekayi (R., T.), Placenticeras placenta (R., T.), Scaphites hippocrepis, S. Conradi (R.) Baculites ovatus (R., T.), B. compressus, Turrilites pauper, Solenoceras annulifer, Belemnitella Americana ; and in the Clay Marls, below the Lower Greensand, Ammonites (Mortoniceras} Delawarensis. Middle Greensand. Montlivaltia Atlantica, Cidaris splendens, Pseudodiadema diatretum, Ananchytes ovalis, Hemiaster parastatus, Terebratula Harlani, Gryphcea vesicularis, Gryphceostrea vomer, Natica abyssina, Isocardia Conradi, Nautilus Dekayi, Baculites ovatus, Sphenodiscus lenticularis. Base of Upper Marl bed. Terebratulina Atlantica, Ostrea glandiformis, Gryphcea Bryani, Crassatella curta, C. littoralis, Turritella pumila, Rostellaria noMlis, Pleuroto- maria Brittoni. The latest and fullest work on New Jersey Brachiopods, Lamellibranchs, Gastropods, and Cephalopods, with illustrations of all the species, is Whitfield's Report, in 4to, U. 8. G. S. r vol. ix., 1885, and vol. xviii., 1892. It contains full references to the works of Morton, Lea, Conrad, and all other authors on New Jersey Cretaceous paleontology. MISSISSIPPI AND ALABAMA. Eutaw group, chiefly Oysters in the marine part. Rotten Limestone : Placuna scabra, Neithea quinquecostata, Gryphcea convexa, G. vesicularis, G. Pitcheri, Ostrea falcata, Eudistes, Mosasaurus ; and in the Tombigbee sand, many Selachian remains, and the gigantic Ammonites Mississippiensis Spillm. Hipley group. Besides the species indicated, in the list for the Lower Greensand group, by the letter R., the following are common kinds; the references to Texas are from Whitfield and Stanton: Ostrea subspatulata (T.), Gryphcea mutabilis, Anomia argentina, Inoceramus proximus, Germlliopsis ensiformis, Cucullcea capax, Pecten quin- quecostatus, Nucula percrassa (T.), Aphrodina Tippana (T.), Veleda lintea (T.), Lunatia obiquata (T.), Pugnellus densatus (T.), Pyrifusus subduratus (T.), Volutomorpha Eufaulensis (T.), Morea naticella (T.), M. cancellaria (T.), Cinulia pulchella (T.), Baculites anceps (T.). TEXAS. (The species of the Upper Cretaceous are wholly different from those of the Lower.) (1) Lower Cross Timbers: Leaves of Salix, Ilex, Laurus, etc. (Shumard); Otodus appendiculatus, and other Fish remains ; Anguillaria Cumminsi White, species of Ostrea, Cerithium, Turritella, Neritina, Scaphites, with Ammonites Swallovi Shumard. (2) Eagle Ford shales : Isastrcea discoidea White, Ostrea congesta Con., 0. belliplicata, Exogyra columbella Meek, Lima crenulicosta Roemer, Inoceramus labiatus, I. latus Sow., /. confertim-annulatus Roemer ; the Ammonoids, Buchiceras Swallovi, Hoplites Deshayesi, MESOZOIC TIME CRETACEOUS. 855 Acanthoceras mammillare, Scaphites Texanus R. ; Ptychodus mammillaris, Lamna com- pressa, L. Texana, Gfaleocerdo, Carcharodon. (3) The Austin limestone (chalk): Rhizopods of the genera Textularia and Globigerina ; also Hemiaster Texanus R., Cassidulus cequoreus Morton, Terebratulina Guadalupce R., Ostrea congesta, Gryphcea vesicularis Lamk., Exogyra ponderosa (young form), E. costata Say, E. columbella, Ostrea larva, Pecten Nillsoni, Inoceramus biformis, I. umbonatus, L subquadratus, I. exogyroides, L labiatus, Eadiolites (?) Austinensis R., Eulima Texana R., Chemnitzia gloriosa R., Nautilus DeTcayi, Baculites anceps, B. asper, Ammonites (Placenticeras) Guadalupce R., A. (Mortoniceras) Texanus R., Mortoniceras Shoshonense, Schlcenbachia dentato-carinata R. (4) The Taylor or Exogyra ponderosa marls: E. ponderosa (very abundant), Gryphcea vesicularis, Ostrea larva, Amusium simplicum Con., Pyrifusus granosus Con. The species have greater resemblance to those of the Atlantic and Gulf borders than to those of the Continental Interior ; and this is true also of the following. (6) Glauconitic beds of northeast Texas : the species of (4), and also Pecten Burling- tonensis, Inoceramus Crispii, Crassatella lineata Shum., Pachycardium Spillmani, Pholadomya Lincenumi, Chemnitzia gloriosa, Purpura cancellata, Pleurotoma Texana, P. Tippana, Anisomyon Haydeni, Nautilus Dekayi, Ptychoceras Texanum, Turrilites helicinus, Helicoceras Navarroense, Baculites annulatus, B. Spillmani, B. Tippoensis, Placenticeras placenta, Belemnitella mucronata. Further, the Eagle Pass beds on the Rio Grande, referred to the age of the Fox Hills and Laramie, contain Ostrea glabra Meek, Anomia micronema, and species of Area, Cyrena, Amm. (Sphenodiscus) pleurasepta Con., and other species. The above names are from lists by Hill. See further, for species of the Glauconitic group and Ponderosa marls that are identical with those of the Ripley and Lower Greensand groups, tables on page 854. On the Invertebrate Paleontology of Texas, see especially F. Rcemer, Kreid. Texas, 1862; also, Pal. Abhandl, Berlin, 1888; Shumard, Acad. Sc., St. Louis, i., 1860, and Boston Soc. N. H., viii., 1861-62; R. T. Hill, Am. Jour. Sc., 1887; Sep. Geol., Texas, vol. i., annotated check-list, Bull. No. 4, Geol. Texas, 1889 ; Proceedings of the Biological Society of Washington, D.C., vol. viii., 1893; Bull. Geol. Soc. of Am., vol. v., 1894 ; C. A. White, on fossils from Texas, Proc. U. S. Nat. Mus., ii., and his Correlation of the Cretaceous, Bull. U. S. G. S., No. 82 ; F. W. Cragin, Texas Geol. Survey, 1893. CONTINENTAL INTERIOR (Upper Missouri region), according to Meek : 1. DAKOTA SERIES. Besides species of fossil plants, Pharella (?) Dakotensis, Tri- gonarca Siouxensis, Cyrena arenarea, Margaritana Nebrascensis, etc. 2. COLORADO SERIES. (a) Fort Benton : Inoceramus labiatus, I. fragilis, I. tenui- costatus, Ostrea congesta, Pholadomya (Anatimya) papyracea, Scaphites larvceformis, S. vermiformis, S. ventricosus, Nautilus elegans ; the Ammonites, A. Mullananus, Mortoniceras Shoshonense, Prionocyclus Woolgari, etc. (6) Niobrara : Inoceramus (avicu- loides) labiatus, L deformis, Ostrea congesta, etc. 3. MONTANA SERIES. (a) Fort Pierre : Inoceramus sublcevis, I. Crispii, I.tenuilineatus, Busycon Bairdii, Neithea quinquecostata, Anisomyon borealis, Lucina occidentalis, Avicula linguiformis ; the Aminonoids, Ammonites complexus and Placenticeras placenta, with Baculites ovatus, B. compressus, Helicoceras Mortoni, Scaphites Conradi, S. nodosus; Nautilus Dekayi. (b) Fox Hills : Anchura Americana, Pyrifusus Newberryi, Cardium speciosum, Mactra alta, Tancredia Americana, Belemnitella bulbosa, Nautilus Dekayi, Placenticeras placenta, Scaphites Conradi, Baculites ovatus, B. grandis. No species of the genera of keeled Ammonites, Prionocyclus, Prionotropis, Morto- niceras, states Stanton, have been found in America above the limits of the Colorado formation ; and further, no species of Heteroceras, Ptychoceras, and Anisomyon occurs below the Montana, no large Baculites, such as B. ovatus, B. grandis, and B. compressus, nor the species Scaphites Conradi, S. nodosus. 856 HISTORICAL GEOLOGY. 4. LARAMIE BEDS at Judith Kiver (Rep. Hayden Survey, vol. ix., 4to), according to Meek, in the lower part : Unio Dance and U. Deweyi, Viviparus, Goniobasis, Sphcerium, Planorbis, Ostrea subtrigonalis in the upper part: Ostrea subtrigonalis (?), Corbicula occidentalis, C. cytheriformis, Goniobasis convexa, etc. Among Vertebrates of the Laramie beds are the following : At Moreau River, South Dakota (west of the Missouri), the Plesiosaurids, Plesiosaurus occiduus and Ischyro- saurus antiquus, both described by Leidy. At the Judith River Basin, remains of species related to the Iguanodon of the genera Palceoscincus, Troodon and Aublysodon of Leidy ; according to Marsh, of Claosaurus, of Ceratopsids and Ornithomimus ; of Plesiosaurus and lachyrosaurus ; also of the Rhynchoceph, Champsosaurus profundns Cope ; and Turtles of the genus Compsemys. At Black Butte, the Ceratopsid, Agathaumas sylvestris Cope. At Castle Gate in southwestern Utah, an important coal-mining village, a species of Claosaurus ; in the Denver group, or Upper Laramie, near Denver, species of Ceratops and Ornithomimus. Some of the Mammals of the Laramie are mentioned on pages 852, 853. Aublysodon mirandus of Leidy (1859, 1868), referred by him to the tribe of Dinosaurs, was based on a number of teeth. Marsh has suggested (1892) that some of the incisors figured may be Mammalian, stating that only the discovery of a tooth of the kind in a jaw will remove doubt. Fossils from the Cretaceous formation of New Jersey were first described by the excellent naturalist of Philadelphia, Thomas Say, in 1820 (Am. Jour. Sc., ii., 34), who then named species of Baculites, Exogyra (instituting this genus), and Terebratula. The beds were called by him "the New Jersey Alluvium." The first reference of the beds to the Cretaceous formation, and first account of their geographical distribution along the Atlantic and Gulf borders, was made by Lardner Vanuxem in January, 1828 (Acad. N. S. Philad., vi.) ; and the first systematic description of the fossils, with figures, by S. G. Morton, in a paper of the same date, which follows Vanuxem's. Vanuxem, in a note to his paper (page 63), alludes to Morton's extensive collections of fossils of New Jersey and Dela- ware, which he had examined in addition to his own. Morton's paper was soon followed by others in continuation. The Radiolarians found by Tyrrell in the Montana group, Manitoba, have been described and figured by D. Rust (Canada Survey, 1892). On the Invertebrate paleontology of the Continental Interior, see especially the publi- cations of Meek in connection with the Hayden Survey and also elsewhere ; also papers by C. A. White, and his Correlation of the Cretaceous ; also T. W. Stanton's Colorado Formation (1893). FOREIGN. ROCKS GENERAL DISTRIBUTION. The Cretaceous formation covers a large part of southeastern England, east of the Jurassic boundary, from Dorset on the British Channel to Norfolk on the German Ocear ; and also a narrow coast region, about and south of Flamborough Head, as shown on the map, page 694, and small areas in northern Ireland and on the islands of Mull and Morven, off Scotland, where it is covered by Tertiary basaltic lavas. Like the Jurassic, it reappears across the British Channel in France and Denmark, and to the east and south over much of Europe. It usually out- crops along the borders of the great Tertiary areas or within them, indicating that the seas of the early Tertiary, which cover so large a part of the conti- MESOZOIC TIME CRETACEOUS. 857 nent, were also, for the most part, Cretaceous seas with still wider limits and larger intercommunications. The London-Paris basin, spreading east- ward to Denmark, was one of these partly isolated areas ; it was 800 miles wide from north to south in the Cretaceous period, 400 in the Jurassic, and about 250 in the Tertiary. Southwestern France and the northeastern half of Spain, making the Pyrenean basin, was another, 450 miles broad ; Switzer- land and a broad area across Bavaria was another. Italy and the eastern coast region of the Adriatic, with a very broad region in northern Africa, in Egypt and Syria to the eastward, made another, the Mediterranean basin. A great Austro- Russian basin spread beyond the Azof and Black seas to the Caspian, the Caucasus, and farther east over large areas in Persia; and in the Neocomian, it is supposed to have extended by the west side of the Urals to the borders of the Arctic Sea. Only parts of the borders of these great areas are at surface Cretaceous, the Tertiary being the overlying formation. It is necessary thus to view the Tertiary with the Cretaceous in order to appreciate the fact that Cretaceous Europe, across from the Bay of Biscay and Spain to its eastern border, was mostly a submerged region. The Mediterranean basin, like that of the West India and Gulf basin in America, was the deeper part of the submerged area. The dry land included the regions of Scandinavia with the Baltic provinces in Russia, a western and northern part of Great Britain, and some isolated areas along the western border and over the central portions of the continent. The resemblance to North American distribution consists in the fact that the dry land was most extensive to the north, and that the deepest waters were about the Mediterranean Sea on the south. The contrast consists in the widespread submergence of the continental surface across from east to west, and the absence of any distinctively Atlantic border region. In India, there is no evidence of marine Cretaceous beds in the great valley of the Ganges, and only small areas near Pondicherry in the south- eastern part of the Peninsula. They cover a large area in Queensland, north- eastern Australia, and occur in some other parts of that continent. They are found also in New Zealand, where they contain valuable coal-beds. In South America, narrow belts of Cretaceous rocks extend, in Venezuela, from Cumana to Pamplona, and from there northward and southward along the Andes, being at an elevation of 9000 to 14,000 feet at the passes of the Portillo and Eio Volcan, and having a height of 20,000 feet. The Upper Cretaceous forms most of the peaks of the eastern Andes, some of the ridges having a height of nearly 19,700 feet. In Peru, latitude 111 S., near the pass of Antaranga, its height is about 15,750 feet, and in the Province of Huamachuco, the Gault reaches a height of 16,405 feet. In Chile, in the Cordillera of Chilian (36 18'), the Cenomanian has a height of nearly 15,000 feet. The Cretaceous are the oldest of the beds exposed over the most of northern South America, the crystalline rocks (Archaean) excepted (H. Karsten). There is a large area also in the eastern part of Brazil. 858 HISTORICAL GEOLOGY. C. A. White has described Cretaceous fossils, from the provinces of Sergipe, Pernambuco, Para, Bahia, and elsewhere, in vol. vii. of the Archives of the National Museum of Rio de Janeiro (1888). Darwin found Cretaceous fossils in Fuegia, on the summit of Mount Tarn and near Port Famine, in the Straits of Magellan; and the author, in 1838, obtained Belemnites, probably Cretaceous, on the shores of Orange Bay, near Cape Horn. 1 SUBDIVISIONS. In view of the very wide and various distribution of these continental Cretaceous beds, and the diversity of conditions as to water, depth, and tem- perature under which they have originated, it is not to be expected that there should be uniformity in the succession of rocks, either as to kinds or as to fossils, since life varies in distribution with variations in the above conditions. As a consequence, the Cretaceous formation is, even in Europe, a formation with or without chalk, with or without limestone, with or with- out sandstones, or chiefly made up of sandstones, and with wide variations in the fauna. The principal British subdivisions are the following : I. LOWER CRETACEOUS. The Neocomian of Thurman (1832), so named from the Latin name of Neufchatel, Neocomium; including (1) the Wealden, and (2) the Lower Greensand, but restricted by some to the Wealden. II. UPPER CRETACEOUS. (1) The Gault or Albian, consisting of clay with some greensand (it is made Lower Cretaceous by most European geologists) ; (2) the Cenomanian, consisting of (a) the Upper Greensand, marl beds, and the Gray Chalk of Folkestone ; (3) the Turonian, the Lower White Chalk without flints ; (4) the Senonian, or the Upper Chalk with flints. Above comes, in Denmark, (5) the Danian, or the Maestricht beds. The Wealden, including the Hastings sands below and the Weald clay above, is about 1500 feet thick in southern England, where it was deposited in the fresh waters of a delta over 20,000 miles in area. The Gault is 100 feet to 200 feet thick. The chalk without flints is a prominent formation across from Flamborough Head, on the east coast of England, to the southern coast, in Dorset. The "greensand" is like that of America (page 68). The chalk con- sists chiefly of Foraminifers, or the shells of Khizopods, but contains also remains of Sponges and other forms of life, which together appear to indicate that the beds were formed at depths of a few hundred feet by some made 300 fathoms or more; they are similar in general character to those now accumulating over the sea-bottom. The flint nodules occur in layers in the chalk. The facts seem to show that the sea-bottom, on account of depth or for some other reason, was in a more favorable condition for growing siliceous Sponges in some places than at others. The material of a flint nodule, while 1 For a note on the discovery, see Am. Jour. Sc., xxxv., 83, 1888. MESOZOIC TIME CRETACEOUS. 859 ordinarily black or grayish-black flint, is sometimes chalcedony or agate, and on the other hand, it is often white exteriorly from admixture with chalk. The fantastic shapes of some flints are often dne in part to the fossils they include. The rocks in northern France or Belgium much resemble those of England. In Germany, above the Lower Cretaceous, there is a large predominance of sandstones and marls. In Switzerland, the Lower Cretaceous of the Jura, about Neufchatel, is mostly limestone ; and of the same nature is the chief part of the Upper in other parts of Switzerland and the Austrian Alps. The same is true for most of the Cretaceous of Italy, northern Africa, Syria, the Mediterranean region being marked in places by coral reefs, Hippurite lime- stone, and other evidences of pure ocean waters. The following are the subdivisions adopted in France and Belgium and Switzerland. (See further on their distinctions, page 864.) 2. UPPER CRETACEOUS. 4. DANIAN. 1. Maestrichtian or Dordonian ; 2. Garumnian (Pisolitic limestone). 3. SENONIAN. 1. Santonian ; 2. Campanian. 2. TURONIAN. 1. Ligerian ; 2. Angouraian. 1. CENOMANIAN. 1. Rhotomagian ; 2. Carentonian. 1. LOWER CRETACEOUS. 4. ALBIAN (= Gault). Vraconnian = Upper Albian, at Cheville in the Valais. 3. APTIAN (= rest of Lower Greensand). 2. URGONIAN (= lower part of Lower Greensand). 1. Urgonian ; 2. Rhodanian. 1. NEOCOMIAN (= Wealden). 1. Valenginian (= Hastings sand); 2. Hauterivian (Weald clay). LIFE. PLANTS. The plants of the Wealden, and the rest of the Neocomian in England and Europe, are Cycads, Ferns, and Conifers, as in the Jurassic, with a show of progress in the first appearance of species of the genera Pinus and AbieSj the true Pines and Spruces, but with no Angiosperms. But in the Gault and the Upper Cretaceous occur leaves of Angiosperms of many common kinds, though all of extinct species ; as the Magnolia, Myrtle, Willow, Wal- nut, Maple, Fig, Holly, besides a Eedwood (Sequoia) ; and there were also Palms, of the genus Palmacites. No remains of Lower Cretaceous Angio- sperms and Palms have been reported from England. Vegetable remains are rare fossils because the beds are mostly marine. The microscopic Protophytes, called Diatoms and Desmids, are found in some of the beds, especially in the flint. The Desmids are far the more common because not siliceous, and therefore not dissolved ; the kinds called Xanthidia are especially abundant, and are similar to those from Devonian hornstone (page 583). Coccoliths are common in the Chalk. 860 HISTORICAL GEOLOGY. 1444 ANIMALS. 1. Rhizopods. Foraminifers are commonly the principal material of the Chalk. Ac- cording to Ehrenberg, a cubic inch of chalk often contains more than a million of micro- scopic organisms, which are chiefly the shells of Rhizopods. Some of the species are repre- RHIZ oro D s.-Fig. 1444, Lituola nautiloidea ; 1445, a, Flabellina S6nted mUCli enlarged in FigS. rugosa; 1446, Chrysalidina gradata; 1447, a, Cuneolina 1444-1447. pavonia. 2. Sponges. Sponges were of like importance in the history of the Cretaceous rocks on account of their siliceous spicules and framework, which were the chief source of the flint. The recent discovery over the ocean's bottom of Sponges whose fibers are wholly siliceous was a revelation as to their importance in flint-making. The species are mostly of the Hexactinellid and Lithistid 1448 1448, 1449. 1449 a 14496 SPONGE. Fig. 1448, Siphonia lobata. ECHINODERM. Figs. 1449 a, 6, Ananchytes ovatus. kinds. One of the Lithistid kind is represented in Fig. 1448, and spicules from various sponges in Figs. 446-460, on page 432, obtained by G. J. Hinde, from a cavity in a mass of flint, which afforded also a multitude of other forms. The Cretaceous Hexactinellids comprised the goblet-shaped Ventriculites, and many other kinds. 3. Corals, Echinoids. Corals and Echinoids were common in some of the limestones, especially those of southern Europe. The Corals were of modern type in being Hexacoralla ; and one Cretaceous genus, CaryopkyUia, has still its many species. Echinoderms were of many genera and species, especially in the Upper Greensand (Cenomanian) and chalk. The Ananchytes ovatus, Fig. 1449, is of the Upper Chalk (Senonian) of England. With it, and also in the Ceno- manian, occur species of Holaster, Micraster, Salenia, Galerites, and others. 4. Mollusks. Lamellibranchs included many species of the genera Gry- phcea, Exogyra, Inoceramus, Trigonia, which are rare after the Cretaceous, or end with it, and also of Pecten, Lima, etc. They comprise also the pecul- MESOZOIC TIME CRETACEOUS. 861 iar Rudistes, of which there are over a hundred species in the Cretaceous, and none later; they are especially common in the Mediterranean region. 1450-1455. 1451 1454 LAMEI.LIBBANCHS, Rudistes Family. Fig. 1450, Hippurites Toucasianus ; 1451, H. dilatatus ; 1452, Kadiolitos Bournoni; 1453, Sphaerulites Hoeninghausi. GASTROPODS. 1454, Nerinea bisulcata ; 1455, Cinulia avellana. Fig. 1450 represents Hippurites Toucasianus d'Orb. (with a small one attached), and 1451, the interior of the shell of H. dilatatus. Figs. 1452, 1453 show the forms of the upper 1456, 1457. 1457 1456 valves, in profile, of species of Eadiolites and Sphcerulites, of the same family. The prominences b, c are for the attachments of muscles. A single species, Radio- lites Mortoni Woodw., has been found in England. Figs. 1454, 1455, are Gastropods of the pecul- iar genera Nerinea and Cinulia, both now extinct. Two of the fresh-water shells from the Wealden are represented in Figs. 1456, 1457, one a Unio, and the other the common Viviparus. Ammonites were in great numbers ; and, as in America, the open-coiled forms are far more abundant than in the Jurassic. Several of the latter are shown in Figs. 1458-1461, and a spiral form, Turrilites, in 1462. Another related form is that of the open-coiled Turrilite, Helicoceras, which has several species in Europe, as well as in America. Nautilus also has many Fig. 1456, Unio Valdensis ; 145T, Viviparus (Paludina) flu- viorum. 862 HISTORICAL GEOLOGY. species. The Ammonites Lewesiensis Mant., from the Lower Chalk of England, has a diameter of a yard. 1458 1458-1462. 1462 CIPHALOPODS, Ammonite Family. Fig. 1458, Crioceras Duvalii ; 1459, Ancyloceras Matheronianum , 1460, Hamites attenuatus; 1461, Toxoceras bituberculatum ; 1462, Turrilites catenatus. Vertebrates. 1. Fishes. The earliest of the Teleost Fishes are first known from remains in the Middle Cretaceous, and with them were Sharks of modern as well as ancient type, with numerous Ganoids. Among Teleosts, the Salmon family was represented by species of Osmeroides (Fig. 1463), 1463. TELEOST. Osmeroides Lewesiensis (x 8 to 14 inches long ; the Perch family, by species of Beryx; the Herrings, by species of Clupea; Mackerels, by several species; the rapacious Saurodonts, by species of the American genera Saurorephalus, Ichthyodectes, Portheus, MESOZOIC TIME CRETACEOUS. 863 Daptinus, etc. Ganoids were numerous, both of Cestraciont Sharks and of Squalodonts, the latter being represented by species of the genera Carcharias, Lamna, Oxyrhina, Odontaspis, Otodus, etc. 2. Reptiles. The Wealden of England, a region of great marshes and lakes, and the beginning of the Cretaceous, has afforded remains of 30 or more species of Dinosaurians, Crocodilians, and Plesiosaurians. The number is very ]arge even for an area of 20,000 square miles (100 miles by 200). But these Reptiles may not all have been cotemporaries ; yet the period was not so long but that one of the Iguanodons that existed in the Lower Weal- den continued on into the Lower Greensand. Moreover, the species known may not be a fourth of those that existed in the region during the Wealden epoch. They included Dinosaurs of nearly all the subdivisions : the Her- bivorous Morosaurids, as Morosaurus (Pelorosaurus) BecJclesii, Cetiosaurus brevis; Stegosaurids, as Hylceosaurus Oweni and Polacanthus Foxi; Ornitho- poda, as Iguanodon Bernissartensis, 33 feet long, /. Mantetti 20 feet long, 1465. 1464. DINOSAUR. Fig. 1464, Iguanodon Bernissartensis (x ). Dollo. 1466, 1. Mantelli, tooth, natural size. Man tell. Hypsilophodon Foxi ; Carnivorous Dinosaurs, as Megalosaurus Dunkeri. And with these and other Dinosaurs, there were some Crocodilians, a Plesiosaurus, Chelonians, and several species of Pterosaurs. The skull of an Iguanodon, from the Wealden of Belgium, is represented in Fig. 1464, and a tooth, full size, of I. Mantelli, from the Wealden, in Fig. 1465. The foot, which is over 4|- feet long, has the three-toed characteristic of the Ornithopods. The genus was named from a resemblance in the teeth to those of the Iguana. Among the Pterosaurs, the genus Ornithostoma of Seeley includes a toothless species from the Cambridge Greensand, related to Pteranodon of America. After the Wealden, Reptiles were less numerous. But both Herbivorous and Carnivorous Dinosaurs continued. The carnivorous Acanthopkolis 864 HISTORICAL GEOLOGY. horridus of Huxley occurs in the Upper Cretaceous, and Megalosaurus Bredai of Seeley at the top of the Cretaceous in the Maestricht beds. Mosasaurids make their first appearance after the Neocomian, as in America ; a Liodon occurring in the Upper Chalk, and Mosasaurus Camperi Meyer (Fig. 1466), in the Maestricht beds, and also at Lewes, England. 1466. Mosasaurus Camperi (x ^). At Gosau in the northeastern Alps, Austria, remains of the horn-cores of Ceratopsids have been found in beds of the Upper G-reensand, and described under the name Struthiosaurus. 3. Birds. Imperfect remains of two species of Enaliornis Seeley have been obtained from the Cambridge Greensand ; and Professor Seeley observes that they may be related to the Hesperornis of Kansas. A species of Palceornis occurs in the Wealden. 4. Mammals. Only one species had been reported up to 1894. It is referred to the Jurassic Marsupial genus Plagiaulax. The only specimen is a molar tooth from the Wealden of Hastings (S. Woodward, 1891). Local Subdivisions and their Characteristic Fossils. 1. LOWER CRETACEOUS. A. Great Britain. 1. The WEALDEN. (a) The Hastings sand and clays, or Lower Neocomian, which have afforded, besides plant remains and fresh-water shells, the bones of many Saurians. (&) The Weald clay or Middle Neocomian (400'-1000'), containing, at a level about 100' from its top, the Paludina limestone, sometimes called Sussex marble, consisting chiefly of fresh-water shells of Paludina flumorum a marble "renowned in the annals of church architecture." In addition to fresh- water shells, and fish remains, there are remains also of Reptiles ; and on the Isle of Wight occur Exogyra sinuata and an Ostrea. The Lower Greensand, 250'-450', overlies the Wealden in southern England, but over- laps northward the Upper Oolytic beds. Contains Ammonites (Hoplites} Deshayesi, MESOZOIC TIME CRETACEOUS. 865 A. (Hoplites) Noricus, Ancyloceras gigas, Diceras Lonsdalei, Exogyra sinuata, Gervillia anceps, Pinna Mulleti. The clays of Speeton cliffs of the Neocomian have afforded marine fossils ; the Lower, the 3 zones of Ammonites (Olcostephanus) Astierianus (lowest), with Toxaster complana- tus, Olcostephanus Speetonensis, Hoplites Noricus; and the Middle, Pecten cinctus, Exo- gyra sinuata, Belemnites jaculum, etc. B. France. The term Neocomian, as first used (by D'Orbigny) was restricted to beds of the age of the Wealden ; his Urgonian (named from Orgon, Bouches-du-Rhone), as used by Lapparent corresponds to the lower part of the Lower Greensand (Atherton clay) ; Aptian, to the rest of the Lower Greensand, except the upper part (Folkestone beds) ; and Albian,to the latter with the Gault. Lapparent includes all to the top of the Gault in his " Infra-Cretace." The Neocomian is divided into (1) the Valenginian (so named from the Chateau de Valengin, near Neufchatel), and (2) the Hauterivian (so named from Hauterive). The Valenginian contains Toxaster Campicheii, Strombus Sautieri, Pygurus rostratus, Nerinea Favrei, N. Meriani ; and the Hauterivian, Dysaster ovulum, Toxaster complanatus, Ostrea Couloni, 0. macroptera, Pinna Mulleti, Trigonia carinata, Ammonites (Hoplites) radi- atus, A. (Engonoceras) Gervillianus, A. (Olcostephanus') Astierianus. The Urgonian contains Heteraster oblongus, Requienia ammonia, E. Lonsdalei, Radiolites Neocomiensis. The upper part of the Urgonian, containing Heteraster oblongus and Requienia oblonga, is the Rhodanian of Renevier. In southern France, toward the Pyrenees, the Urgonian contains Requienia Lonsdalei with Orbitulina conoidea, 0. dis- coidea, Nerinea gigantea, Heteraster oblongus. The Aptian (from Apt, in Vaucluse) contains, at the Perte-du-Rhone, Epiaster poly- gonus, Plicatula placunea, Ostrea aquila, Trigonia caudata. In Germany, the Lower Cretaceous to the base of the Gault is the Hils formation or Neocomian. In northwestern Germany, in Hanover, on the borders of Holland, the Hastings sand is represented by the Deistefsandstein, containing some coal, remains of Reptiles including the Iguanodon, and many plants ; and above this is the Weald clay (Walder- thon) 70'-100'. The marine beds in north Germany contain Toxaster complanatus, Ammonites (Olcostephanus') Astierianus, Hoplites radiatus, Hoplites Noricus, Exogyra Couloni. Next is the Gault, the lower part of which is made the equivalent of the Lower Greensand of England, or the Aptian, with Ammonites Martini, A. Deshayesi, Exogyra Couloni, and the rest the English Gault, with Ammonites (Schlonbachia) inftatus, A. (Hoplites) auritus, A. (Hoplites) lautus, A. (Hoplites) interruptus. 2. UPPER CRETACEOUS. 1. Albian or Gault. In England contains Ammonites (Hoplites) auritus, A. (Schlon- bachia) varicosus, A. (Schlonbachia) cristatus, A. (Acanthoceras) mammillaris, Inocera- mus sulcatus, Pterocera bicarinata, Hamites attenuatus (Fig. 1460), Toxoceras bitubercu- latum (Fig. 1461), Turrilites catenatus. Includes 3 zones according to Barrois, those of (1) Schlonbachia inflata; (2) Hoplites interruptus ; (3) Acanthoceras mammillare. In France, near Montierender, there are the Ammonites : (I) Schlonbachia inflata ; (2) Hop- lites splendens, Hoplites auritus, Acanthoceras mammillare, Hoplites Deluci, Acanthoceras Lyelli; (3) Turrilites catenatus. The Gault is the Flammenmergel of Germany with Schlonbachia inflata, Hoplites lautus, Hoplites auritus, Aucella gryphceoides. 2. Cenomanian. In England consists of (1) the Upper Greensand, (2) Chloritic or Glauconitic Marl, (3) Chalk Marl, (4) Gray Chalk. The Upper Greensand contains below, Exogyra conica, Pecten quadricostatus, Inoceramus concentricus, Cardium Hillanum, Trigonia scabricula, Hamites alternatus, and above, Holaster nodulosus, Pecten asper, Terebratula biplicata, Rhynchonella compressa. The Chloritic Marl contains Terebratula DANA'S MANUAL 55 866 HISTORICAL GEOLOGY. biplicata, Solarium ornatum, Plicatula inflata, Schlonbachia varians. The Chalk Marl contains Holaster Icevis, Rhynchonella Martini, Turrilites costatus, Inoceramus striatus, Schlonbachia varians. The Gray Chalk, which is the upper part of the Cenomanian, called also the Lower Chalk, includes in England the zones : (1) of Scaphites cequalis and Plocoscyphia mceandrina ; (2) of Ehynchonella Martini; (3) of Holaster subglobosus ; (4) of Belemnitella plena. In France, the beds in the valley of the Seine, called the " Craie glauconieuse " or Rhotomagian of M. Coquand, contain Holaster suborbicularis, Cidaris vesiculosa, Am- monites (Acanthoceras*) Rhotomagensis, Acanthoceras Mantelli, Turrilites costatus, Pecten asper, Inoceramus striatus. The overlying Carentonian of Renevier is the zone of Ostrea biauriculata, Belemnitella plena, Caprina adversa. In Germany, the Cenomanian is the Lower Planer, affording Pecten asper, Ostrea diluviana, Catopygus carinatus, Schlonbachia varians, Acanthoceras Rhotomagense, Acanthoceras Mantelli, Turrilites costatus, T. tuberculatus. Three zones are recognized : (1) zone of Pecten asper and Catopygus carinatus ; (2) of Schlonbachia varians; and (3) of Acanthoceras Rhotomagense and Holaster subglobosus. 3. Turonian, or the Lower White Chalk without flints, with the nodular chalk of Dover at the top, contains Holaster planus, Ananchytes ovatus, Rhynchonella Cuvieri, R. pli- catilis, Ostrea vesicularis, Spondylus spinosus, Ammonites (Pachydiscus) peramplus, Hemiaster Verneuili. Scaphites Geinitzi. In England the zones recognized are: (1) of Rhynchonella Cuvieri; (2) of Tere- bratulina gracilis ; (3) of Holaster planus. In France, (1) the Ligerian (named from the basin of the Loire) (the Middle Planer of Germany) is the zone of Exogyra columba, Inoceramus labiatus, Pinna decussata ; and (2) the Angoumian, the zone of Terebratula gracilis, Holaster planus, and of Radiolite and Hippurite limestone in the eastern Alps. 4. Senonian, or the Chalk with flints (named from a locality of chalk at Sens). Contains Ananchytes ovatus, Micraster cor-bovis, M. cor-anguinum, M. glyphus, Inoce- ramus labiatus, Spondylus spinosus, Ostrea vesicularis, Belemnitella quadrata, B. mucro- nata, Scaphites pulcherrimus. (1) The Santonian is the zone of Micraster brevis, M. cor- anguinum, and Inoceramus digitatus; (2) the overlying Campanian is the zone of Ostrea vesicularis, Belemnitella mucronata, B. quadrata, and includes the Upper Quadersandstein, the Lemberg chalk, and chalk of Meudon and of Reims. 5. Danian. The Lower Danian or Maestrichtian or Dordonian is the zone of Nautilus Danicus, Ostrea decussata, Belemnitella mucronata, Baculites Faujasi; the Upper or Garumnian (named from Garonne), that of Micraster tercensis, and includes the chalk of Faxe, fresh-water beds in Provence, and marine and brackish-water beds in the Pyrenees, 100' to 1000' thick. From the Danian comes the Mosasaurus Camperi (page 864). In Provence, southeast France, the SENONIAN, overlying the Angoumian, or limestones containing Hippurites Petrocorriensis, etc., includes, according to M. Toucas (1891) : 1. The SANTONIAN (a) with Hippurites giganteus, Rhynchonella Petrocorriensis, Tri- gonia limbata ; (6) with Amm. tricarinatus, Hippurites brevis, Micraster brevis; (c) Am- monites Texanus, Inoceramus digitatus, Cidaris clavigera; (d) Ammonites Texanus, Actinoceras verum, Hippurites Corbaricus, Cidaris clavigera. 2. CAMPANIAN, (a) Hippurites dilatatus, H. Toucasi, H. socialis, Ostrea vesicularis; (ft) Hippurites dilatatus, H. Jloridus, Ostrea Merceyi, Schizaster atavus ; Upper, (c) Ci- daris cretosa, Ostrea Matheroni, Lima decussata; (d) Ammonites Gallici, Nerinea bisul- cata, Hippurites, Hemiaster Regulusanus. The following species are reported from different continents : Ostrea larva, North America ; Europe ; India. Gryphcea vesicularis, North America ; MESOZOIC TIME CRETACEOUS. 867 Europe ; southwest Asia. Exogyra Icevigata Sow. , Europe ; Colombia, South America. Exogyra Boussingaultii D'Orb., Europe ; Colombia, South America. Inoceramus Crispii Mant., North America; Europe. Inoceramus latus Mant., North America; Europe. Inoceramus mytiloides Mant. , North America ; Europe. Neithea Mortoni, North Amer- ica ; Europe ; India ; Peru, South America. Pecten circularis Goldf . , North America ; Europe; India; Peru; South America. Trigonia limbata D'Orb., North America; Europe ; India. Trigonia aliformis Sow., North America ; Europe ; southwest Asia ; Colombia, South America. Trigonia longa Ag., Europe ; Colombia, South America. Hippurites organisans, Europe ; southwest Asia ; Peru and Chile, South America. Nerinea bisulcata D'Arch., North America (Texas) ; Europe. Baculites anceps, North America ; Europe ; Chile, South America. Ammonites vespertinus Mort., North Amer- ica ; Europe. In South America, in the Argentine Cordillera, Behrendien found the following European Cretaceous species: Hoplites dispar D'Orb., H. Desori Pictet, Lithodomus prcelongus D'Orb., Corbula Neocomiensis D'Orb., Mytilus simplex and M. Carteroni D'Orb., Exogyra subplicata Roam., Astarte obovata, and others (1892). Two Cretaceous fossils from St. Paul's and St. Peter's, islands in the straits of Magellan, have been described by C. A. White (Proc.U. S. Nat. Mus., xiii., 13, 1890), namely a large Ham ites, probably H. elatior of Forbes, a species collected by Darwin, and a large Lucina. In La Plata, in South America, the Cretaceous (probably Lower Cretaceous) has afforded, according to Lydekker (1893), Dinosaurs, of new genera, two of the Sauropod type, Titanosaurus and Argyrosaurus, and one Microccelus, of undetermined relations. The Cretaceous of Brazil along the coast region between 3 and 13 S. probably constitutes the Abrolhos Islands, and is found also in the interior along the Puriis. The Bahian group of Hartt, supposed to be Neocomian, has afforded Saurians ; the Sergipian, Upper or Middle Cretaceous, contains Ceratites and Ammonites, some identical with species of the Texas Cretaceous. The Continguiban group, probably Senonian, as in the Province of Sergipe, contains Ammonites and Inocerami. The Amazonian group of Puriis Upper Chalk or Maestrichtian has afforded remains of Mosasaurs and Turtles. GENERAL OBSERVATIONS ON THE CRETACEOUS PERIOD. GEOLOGICAL AND GEOGRAPHICAL PROGRESS. 1. General progress. Continental progress in North America previous to the Cretaceous period was chiefly interior work ; the work of the great Interior Continental seas, endogenous, as it has been styled. During the Cretaceous period, this endogenous work was continued over the Western Continental Interior ; but, in addition, progress went forward largely through sea-border work, on both the Atlantic and the Pacific sides. On the Atlantic, after marine formations began, no outside ridges or elevated land are sup- posed to have existed ; and this appears to have been the fact also on parts of the Pacific border. In Europe, the rock-making continued to be essentially Interior Conti- nental throughout the period. The beds of Mull, Morven, and Antrim were deposited within one of the continental troughs ; for the Archaean Hebrides existed outside, and probably were a longer range than now. It was the same sinking trough, moreover, in which beds had been deposited during earlier Mesozoic times. 868 HISTORICAL GEOLOGY. 2. Changes at the close of the Lower Cretaceous. After the earlier Cretaceous, the emergence of the Mexican plateau took place, shutting off the Atlantic waters from the Pacific; and at the same time, movement change occurred in Texas. According to Hill, faults and flexures were produced, especially in the vicinity of Austin. The general direction of the faults in the region is N. 20 E. The amount of displacement is gen- erally less than 100 feet ; but in the chief fault it is 500 to 750 feet, and the course is marked by an escarpment 100 to 250 feet high. Along the faults the beds are in some places flexed, and the limestone is rendered crystalline. Moreover, there is an abrupt transition in species in passing from the Lower to the Upper Cretaceous. The Potomac beds, of the Atlantic border, underwent some change in level and some surface erosion ; but no upturning. On the California coast the continuity of the Shasta-Chico series indicates that the general subsidence mentioned by Diller as in progress during the Cretaceous period was not interrupted at the close of the Lower Cretaceous. But in Western British America, the increased subsidence which introduced the Upper Cretaceous, and spread the sea over the Continental Interior, is supposed by G-. M. Dawson (1890) to be marked in a deposit of marine conglomerates, occurring in many places in the southern part of British Columbia, in the Queen Charlotte Islands, northward about the Upper Yukon, and eastward along the line of the Eocky Mountains. Dawson reports also that at this stage of the Cretaceous, or near it, there was renewed volcanic activity in the Queen Charlotte Islands and in the Kocky Mountain Range. BIOLOGICAL CHANGES AND PROGRESS. Part of the biological history of Mesozoic time has already been reviewed. Still greater changes took place in this later portion, and these now come under consideration. Plants: Cycads, Angiosperms, Palms. The Cycads, the most charac- teristic feature of the Trias sic and Jurassic, had their maximum develop- ment during the latter period. They were still prominent, however, in the forests of the Early Cretaceous, and flourished even in the Arctic regions on Greenland, Spitzbergen, and Alaska; but they were subordinate to the Conifers, and, in the Upper Cretaceous, to the Angiosperms. At present there are only about 50 species of Cycads. The line leading up to Angiosperms is uncertain. It is a notable fact that remains of plants of this class are wholly absent from the Wealden of England and from the Kootanie of America, and that only one species of doubted locality has been reported from the Neocomian of Europe. The 75 species identified by Fontaine from the fossil leaves of the Potomac formation of eastern America show that the trees were then well established in the American forests, although Conifers were by far the more numerous. But still, as Fontaine shows, they leave their origin unexplained. MESOZOIC TIME CRETACEOUS. 869 The Palms came in during the Middle Cretaceous as the decline of the Cycads made progress. It is supposed probable that they were in the successional line of some type of Cycads, since they approach them in their foliage, in their usually simple stems, and in having the pithy interior traversed by bundles of woody fibers. Progress in Mollusks : Culminations under the type. The Tetrabranch Mollusks, which include the Nautilus and Ammonite tribes, pass their climax and decline in the Cretaceous period. The Nautiloid, which commenced with a straight body and a shell no longer than the little finger, and was continued in curved and coiled forms, and reached its maximum in the Carboniferous, is continued to the present time, but only in two or three species of Nautilus ; and these are the last of the Tetrabranchiates. The Ammonite section, which commenced with the closely coiled Goniatite in the Early Devonian, became increasingly complex in the flexures of the septa, and finally two to three feet in diameter in the Jurassic and Cretaceous seas, where it numbered thousands of species. It disappeared entirely, or nearly so, at the close of the Cretaceous. The Dibranchiate Mollusks, or the Cuttle-fishes, whose shells are internal when any exist, are known first from the later Triassic beds. Under the Belemnite family they become very numerous in the Cretaceous, and apparently end at its close. But other Cuttle-fishes were continued; and probably the giant species of modern Newfoundland and other seas, having bodies 12 to 15 feet long, arms of 25 feet, and eyes of 8 inches diameter, the largest in the animal kingdom, are evidence that the type, and the type of MolluskSj has now its time of culmination as to grade of species, though not as to numbers and predominance in the marine fauna of the world. Fishes: their culmination in Mesozoic time. The type of Fishes is supposed to have culminated as early as the Triassic in the Ceratodus and related Dipnoans, which have rudimentary arms in the fins, essentially lungs as well as gills, and other Amphibian-like characteristics. The line to the Teleosts, through the Amioids, was a declining line. In some respects the Teleosts are more highly specialized, but not in a way toward superiority ; they are purer representatives of the Fish-type, and better illustrate the fact that the Fish-type is a low style of Vertebrate. The Selachians hold to their early characteristics of a cartilaginous or semiosseous skeleton, of gills without gill-covers, and of a heterocercal or vertebrated tail. The Cestraciont Sharks, which were common in the Cretaceous, became fewer afterward, and now only four species exist and these live in Australian and Japan seas. The Squalodonts, or Sharks of modern type, reached later their time of maximum display. Decline in Amphibians. Amphibians, so far as registry gives evidence, were few in species after the Triassic period. In the scale-covered and large- toothed Labyrinthodonts of the Permian or Triassic periods they passed their maximum as to size, grade, and numbers. No American, British, or Euro- 870 HISTORICAL GEOLOGY. pean species of Cretaceous Labyrinthodonts are yet reported. The species were too few and too largely terrestrial to have secured frequent fossiliza- tion. Reptiles. The Reptiles of the Cretaceous are for the most part a con- tinuation of Jurassic types, without marked evidence of upward progress. The Horned Dinosaurs, or Ceratopsids of Marsh, probably the latest of the larger species, while showing striking advances toward Mammalian forms in the bovine or rhinoceros-like horns and the two-pronged teeth, are a degenerate group, specialized downward, not upward. As Marsh states, they have the largest heads and smallest brains of any of the Reptile race. The Mosasaurids also, exclusively Cretaceous species, illustrate profound degeneration. For, in these Snake-like species, the Lacertian type becomes enormously multiplicate posteriorly in the vertebral column; the legs are reduced to fins, as in Plesiosauriaus, the posterior part of the body is turned into a fish-like skulling organ, and made the chief means of locomotion ; and the pelvic girdle has lost connection with the vertebrae, there being no sacrum. Here degeneration has developed, not imperfect limbs and a defective skele- ton, not something between a Fish or Amphibian and a Reptile, but a pro- foundly decephalized Reptile, adapted to aquatic life as if its outcome. The last of the Mosasaurs in America occur in the Montana Cretaceous ; in Europe, in the beds of Maestricht. Snakes are known from the American Laramie, and also from the Cretaceous of France. They were no doubt successors to an aquatic type, and related, it is supposed, either to the Mosasaurs, or to the Dolichosaurs of the English Chalk. The true Crocodilians have a heart of four cavities, and traces of a diaphragm ; and the teeth are implanted in sockets. But these high charac- teristics lose part of their apparent significance in view of the fact (1) that the four-cavity heart, after all, does not prevent the commingling of the venous and arterial blood before it enters the system ; (2) that the character of teeth in sockets began in the Permian ; and (3) that the animal has limbs so short that it "drags its body somewhat along the ground/' in true Reptilian style. The Dinosaurs, on the contrary, stood on long limbs like a Mammal, and had nearly the same freedom of locomotion. They were, however, as has been explained, merosthenic Reptiles, that is Reptiles having great and powerful hind limbs as the chief organs of locomotion, with usually small fore limbs and small brains. If they were the highest of Reptiles, then the Reptilian type reached its perfection under a merosthenic structure. But the distinction of highest, as remarked on page 797, probably belongs to the Pterosaurs, which are eminently prosthenic. The largest species of the group existed in the Cretaceous period. It is not improbable that they had a double heart, like the Crocodiles, and one as good as that of the Birds. MESOZOIC TIME CRETACEOUS. 871 There are grounds enough, therefore, for the conclusion that the class of Reptiles culminated in the latter half of the Reptilian age. The reality of the Reptilian feature of the era comes out strongly on comparing the great Reptiles in the Wealden as to size and numbers with those of the present time. Now, in India, or the continent of Asia, there are but two species of Reptiles over 15 feet long ; in Africa, but one ; in all America, but three ; and not more than six in the whole world ; and the length of the largest does not exceed 25 feet. During the Wealden there lived in England alone 16 large Dinosaurs and 12 Crocodiles, besides a Plesiosaur and three Ptero- saurs. The Reign of Reptiles becomes more strongly pronounced when the little Marsupial Mammals of the era are brought into view by way of contrast. Birds. Since Birds are so poorly represented among fossils, little can be said as to progress in the Cretaceous period beyond the fact that part of the Cretaceous Birds, as known first from Marsh's discoveries, retained the teeth of the Jurassic Birds ; and some, even the low character of biconcave vertebrae. They had lost the Reptile-like bones and fingers of the fore limb, and the long tail existing in the Jurassic species, and had, in general, the style of vertebrae characterizing modern Birds, besides modern features in most other respects. It is also a fact of interest that already degenerate forms were in exist- ence under the Bird-type ; for such is the Hesperornis, as shown in its obsolescent wing-bones and wings, a feature that reduced it to the meros- thenic condition of an Ostrich and a Dinosaur. Thus, between the Middle Jurassic and Middle Cretaceous the Bird-type reached essential perfection, though not advanced to its highest stage ; and also it passed along at least one line downward to Ostrich-like imperfection. The presence of teeth is not a structural imperfection. Their absence looks much more so ; but it is not inconsistent with a high and advancing grade of structure in all other respects. Progress in Mammals. The Monotremes and Marsupials from the Creta- ceous formation show little progress in Mammals beyond the condition in the Jurassic period nothing, up to the present time, that bears the decided character of a placental Mammal. As the known fossils are mainly teeth and jaws, full comparisons are not yet possible, and certainty of conclusion as to the question, Marsupial or not, is not yet, in all cases, possible. Contrast of the European and North American marine faunas. The contrast between the marine species of Europe and North America, which characterizes the Early and Middle Mesozoic (page 792), continues, but in diminished degree, into the Cretaceous period. The following table gives: the number of species that have been described from the Cretaceous beds of Great Britain and North America, under the tribes mentioned in the first column; the former from Etheridge, as enumerated by him in 1885; the latter, by Whitfield, in 1894. 872 HISTORICAL GEOLOGY. Great Britain, 1885, American, 1894, Etheridge K. P.Whitfleld Corals 76 27 Echinoderms 201 65 Brachiopods 106 28 Lamellibranchs 476 1329 Gastropods 298 839 Ammonoids 206 224 Nautiloids 20 12 Belemnites 14 19 Crustaceans 110 17 The contrast is equally great with the marine fauna of the Parisian and Mediterranean basins in Europe. It will be noted that the American species are from all North America. The species are, it is true, but imper- fectly studied ; yet the contrast, if all were known, would be strong. Great Britain leads in species of clear seas, and those of moderately deep water Corals, Echinoderms, and Brachiopods ; and if the comparison were confined to the Atlantic border of North America, immensely so in Ammonoids and Nautiloids. The number of both groups from this border is only 24, and that of Echinoderms less than 15. But in number of species of Reptiles America is far ahead of Britain and Europe ; and probably because its broad Western Interior had a vast extent of shallow sea-borders and emerging lands, and thus afforded them especially favorable conditions for existence. CLIMATE. During the Cretaceous period, a warm climate still prevailed over the earth even to the poles, but with some cooling during the closing part of the period ; and in North America with a great Central Interior Sea, to the end of the period, the climate was moist. The Cycads and associated species of plants in the lower Cretaceous beds of Greenland indicate, according to Heer, a mean temperate of 21 C. to 22 C., or about 70 F. to 72 F. This temperature is that of Cuba. The facts prove that a somewhat similar tem- perature prevailed at the same time over Spitzbergen and in Alaska, where the same flora existed ; even along the Atlantic border at least as far north as Long Island ; in the region of the Kootanie beds in Montana and the neigh- boring part of British America ; and over more western North America to Alaska. The Gulf Stream of the Atlantic may account in part for the extension of so high a temperature to Greenland; and a like stream over the Pacific, for that to Alaska. The plants of the Vancouver coal-beds, and those of the Patoot beds in Greenland, which Dawson refers to the age of the Montana series, he com- pares with those of Georgia at the present time, where the mean tempera- ture, he states, is about 65 E. The Dakota plants of Kansas and elsewhere, with those of the Mill Creek group, Canada, and the Atane of Greenland, MESOZOIC TIME CRETACEOUS. 873 are intermediate in kinds, some Cycads being present in Greenland as well as Kansas, and evidently indicate an intermediate temperature. The flora of the Laramie, without Cycads, is, according to the same authority, "not a tropical, but a temperate flora." The testimony as to temperature from the animal life of the Cretaceous seas bears in the same direction with that from plants. There appear to have been no true coral reefs in the British seas; but they were present beyond doubt in the Mediterranean basin. The facts lead to the inference that the temperature of the waters about the British Islands was below a mean of 68 during the coldest winter month, but not much below, while a large part of southern Europe was within the Coral-sea limit. Texas was in all probability included by the same temperature boundary, although no true coral reefs and not many species of Corals have yet been reported from the region. The distribution of a like fauna, for the most part, in the Lower Green- sand group of New Jersey, the Eipley group of the Gulf border, and the Montana division of the Cretaceous of Texas and the Western Continental Interior testifies to a nearly common temperature in the waters through this long geographical range. But it cannot be inferred that in the earlier Colorado epoch, or the later Laramie, the temperature was alike in the waters on the Atlantic border and in those of Texas or of the Interior Con- tinental sea ; for the influencing conditions were widely different ; and hence, even if there were a full series of fossils, there would be marked differences in the cotemporaneous beds of the Interior and the Atlantic border. The Texas waters were within the subtorrid influences of the Mexican Gulf, with no probable source of cold in Arctic currents. But on the Atlantic border the Labrador current may have much modified the temperature of the waters, even if partly shut off by the closing of the Straits of Belle Isle. The coast had, apparently, no Cape Hatteras, and the waters of the Gulf, therefore, had free sweep from the tropics to Cape Cod; and this would have reduced the effect of any Arctic flow to a minimum. GONDWANA LAND. The belt of emerged land between India and South Africa, mentioned on page 737, is supposed to have continued to exist through the Jurassic and Cretaceous periods. K. D. Oldham remarks, in his paper of 1894, speaking of the contrasts of the fauna of eastern and western India, that in western India the Jurassic fossils belong to a fauna that is represented in the north of Madagascar, in northern and eastern Africa, and also in Europe, differ- ing so completely from the fauna of eastern India, that "only a few species of world-wide range are found in both." Further, the remains of plants in the Jurassic Rajmahal series of the east coast of India are mostly identical with, or closely allied to, the species of the Uitenhage series occurring near the coast of South Africa, and now regarded as 874 HISTORICAL GEOLOGY. Neocomian or Lower Cretaceous ; besides, at least one species of shell! occurs in both regions. It is thus shown that the belt still existed during the early Cretaceous, and that, at the same time, as he observes, some barrier along the region separated in India an eastern zoological province from a western. With reference to the connection of South Africa with Australia, all known facts would be explained if it were confined to the- Permian and early Triassic periods. POST-MESOZOIC REVOLUTION: MOUNTAIN-MAKING AND ITS, RESULTS. The upturning. The close of Mesozoic time was marked by the making of the greatest of North American mountain systems. The upturnings took place along the summit region of the Rocky Mountains, where over a broadi belt, as long probably as the western side of the continent, a series of geosynclines had been accumulating deposits ever since Archaean time. This mountain system of North America, which stands as the Mesozoic time boundary, is the Laramide system already described, explained, and illustrated on pages 359-364. The system includes the Wasatch range,, and others to the north and south. Another figure (Fig. 1467), representing. a section of the Lower Cretaceous in the eastern mountain range of Mexico,, northwest of Monterey, is here added from a paper by R. T. Hill. The' beds stand in a series of nearly vertical anticlines and synclines, froiii 1467. Section showing the folding of the Comanche limestone in the eastern mountain range northwest of Monterey^ E. T. Hill. participation in the system of Laramide upturnings. A section showing vertical beds of limestone and a flexure in the Chinate Mountains, 25 miles north of Presidio, not far from the boundary of Texas, is published by C. A. White in his Correlation Report on the Cretaceous of North America, Further, Streeruwitz has given sections illustrating the upturned condition of the Cretaceous formation of the Sierra Blanca and other mountains in Trans-Pecos, or western, Texas. The great belt of orogenic work extending from the Arctic regions; through North America, was probably paralleled by like work, of equal extent, in South America, but on a more eastern line. A long lesson with regard to the comprehensiveness of mountain-making forces and work is afforded by the single case of North America ; and it comes with tenfold emphasis if the western borders of the two Americas, through 120 of MESOZOIC TIME CRETACEOUS. 875 latitude, or a third of the circumference of the globe, were undergoing simultaneous orogenic movements, with like grand results. The deposit-making, preparatory to the Lararnide system of ranges, began, as has been stated, in the Cambrian, and went forward, with some large interruptions, until the subsidence in the geosynclines of deposition amounted to 25,000 feet. While the Laramie epoch was passing, there was a deepening of 10,000 feet in some places during the Cretaceous period alone, and in Montana over 7000 feet if the estimates of thickness are right. As once before stated, it is not supposable that the Archaean ridges bounding such troughs participated in the great subsidence. Assuming the load of sediments to have caused the sinking, in accordance with the isostatic theory, the trough would have been made in the waters off the shores, and would have been greatest a little distance out from the shores ; and the same might be a consequence if lateral pressure were the cause of the subsidence. The denudation of the ridges would have caused them to rise rather than sink. The earlier movements connected with the upturning appear to have begun before the Laramie depositions were completed, producing, according to Cross, a small unconformity in bedding between the Lower Laramie and the Denver beds, besides unconformity by erosion. The latter is described by Weed as marking the junction of the Lower Laramie and the Livingston beds. But the erosion-plane occurs at a level 200 feet below that of a brackish-water bed, abounding in Oyster shells, like those of the Lower Laramie, showing that true Laramie conditions still prevailed, and that the erosion was an event of minor importance. If the orogenic work had actually begun, violent currents in the water may have been produced where quiet deposition had before been in progress ; and then great excavations of the earlier-made beds may have been occasioned, followed by depositions of con- glomerates and other coarse beds. Moreover, earthquakes and earthquake waves from the adjoining sea may have been an agent in producing erosions of the unconsolidated strata. The erosion at the base of the Upper Laramie has been supposed to amount to several thousands of feet and to have taken place as a result of an eleva- tion of the region to this height ; and this elevation has been thought necessary for the supply of the Paleozoic material of the conglomerates. But such a lift of the region would have changed the climate, and through consequent river-erosion would have cut down the Laramie formation into mountain valleys and ridges ; and it would also have exterminated the fauna and flora ; when, in fact, horned Dinosaurs existed after it, while the Denver beds were in course of deposition, and their bones are associated with those of various other Dinosaurs in regions not far distant. Igneous eruptions were also a feature of the early stages of the orogenic movements, and also of its latest. The Wasatch^ as described by King (see map, page 360), had its outflows of trachyte chiefly from the region of greatest wrenching between the main range and the Uinta plateau. 376 HISTORICAL GEOLOGY. The laccoliths of the Henry Mountains in southern Utah (page 301), according to Gilbert's descriptions, are other products of this time of dis- turbance; and so also, as remarked by Hills, those of the Spanish Peaks in southern Colorado. Other eruptions of the epoch contributed to the making of some of the remarkable silver and lead mines of the Rocky Mountain region. S. F. Emmons, in his excellent Keport on the famous Leadville region (page 340), briefly considers the question of the age of the veins. He points out the fact that some of the largest eruptions preceded the Laramie upturning, while others attended the upturning ; but he leaves the question as to the precise time of vein-making undecided. Emmons also considers it probable that a large part of the eruptive rocks of Colorado are of the same Laramide epoch. According to Iddings, the igneous eruptions in Wyoming and Montana and the adjoining Yellowstone Park went on near, and at, the close of the Cretaceous. The rocks are largely andesytes of various kinds, much like those of Colorado. They occur as dikes, intrusive sheets, and laccoliths ; and later in the epoch of eruption, probably in the early Tertiary, volcanic cones were thrown up. In Montana similar eruptive conditions, of the same epoch, have been observed by J. E. Wolff (1892) in the Crazy Mountains, producing intrusive sheets ; and among the rocks occur elseolite syenyte, and varieties containing neph elite and sodalite. Similar rocks occur, according to Lindgren (1890, 1893), in the Highwood Mountains, farther north. The occurrence of dikes of sandstone, as described by Cross (1894), in the granite of the region of Pike's Peak, evidently filling fissures in the granite, may be mentioned here, although their time of origin is uncertain. They occur on the west side of the Manitou Park. They are narrower below, and sometimes branch downward. The width varies from 300 yards to a few inches and even a thin film. The rock is an even-grained quartzose sandstone, usually as hard as quartzyte, with some limonite among the grains as cement. In India the eruption of the "Deccan traps," the most enormous on record, took place probably, according to Blanford, at or near the close of the Cretaceous. The facts are mentioned on page 299, under the subject of non-volcanic igneous eruptions. The eruptions at the close of Mesozoic time mark the commencement of an eruptive period in the earth's history, which had its maximum effects during the following Tertiary period. Disappearance of species. The disappearance of species at the close of Mesozoic time was one of the two most noted in all geological history. Probably not a tenth part of the animal species of the world disappeared at the time, and far less of the vegetable life and terrestrial Invertebrates ; yet the change was so comprehensive that no Cretaceous species of Vertebrate is yet known to occur in the rocks of the American Tertiary, and not even a marine Invertebrate. The only species in North America known to have continued on into the Tertiary are plants, some of which existed still in the Miocene, and a few differ little from existing species. Here ended not only the living species of Dinosaurs, of Mosasaurs, and Pterosaurs, but these tribes of Reptiles. This was true also of the Belemnites, so far as MESOZOIC TIME CRETACEOUS. 877 fossils give information, and, with a single doubtful exception, of the Am- monites ; and, among other Mollusks, of the genera Exogyra, Diceras,. Requienia, Hippurites, Radiolites, Pterinea, Inoceramus, and others. Part of the change had been accomplished before the time of the catastrophe, for decline had made much progress in the Cycads, Ammonites, Belemnites,. and in the Reptilian tribes. But still the destruction was great, world-wide,, one of the most marvelous events in geological history. Among the larger land animals the species most likely to have escaped extermination are the Mammals ; for many of them had no doubt already accustomed themselves to the higher lands or ridges of the continents, and their covering of fur would have made adaptation to a colder climate easy. The Birds also would have been to a large extent tenants of the interior and denser forests of the con- tinent of the time. The Pterosaurs might have had, perhaps, an equal chance with the Birds, but for the absence of a coat of feathers. As to the cause of the epochal disappearance of species, the remarks on the like event after the Appalachian revolution, on page 735, apply also here. The Laramide orogenic disturbance in America passed with no marked contemporary movements in Europe, none sufficient to account for the thoroughness of the disappearance of species. Change by modification had its marked effects, for it has always been in progress ; but extermination must have been the more prominent method of bringing about the great result. Causes of extermination. Since the destructions were to a very large extent marine, the oceanic circulation was probably one means of destruc- tion. The world, by the end of the Cretaceous period, had become more diversified than ever before in its zones of temperature. The emergence from the ocean of a third of North America had taken place, and probably of as much of South America, and of large portions also of the other con- tinents, and this would have determined some lowering of the earth's mean temperature, cooling both the air and oceanic waters. The cooling, during the Cretaceous period, it is certain, was great enough to drive Cycads from the Arctic regions to latitudes that are now at the middle of the Temperate- Zone. If the change had made the Arctic waters only 15 F. colder than, they were during the Cretaceous period, the polar waters, as they flowed southward, would probably have been exterminating to the greater part of the^ life of coast regions along the shallower waters, and down to such depths as. the cold current reached. Such a cause might make a complete break in the succession of species in a region, without any break in the succession of beds, as happened in New Jersey (page 821). Its action would have been least on the western coast of North America, because of the shallowness of Bering Strait. Moreover, under these circumstances temperature would have worked similarly over the land, forcing Cycads southward, and putting unfavorable conditions into the old haunts of Reptile life. The other most probable cause of destruction to life is that from earth- quake waves. The making of a mountain system along the whole length of $78 HISTORICAL GEOLOGY. a continent, causing displacements of the rock formations along lines measuring hundreds of miles in extent, must have been attended by a succession of earthquakes of unwonted violence, which would have caused destruction by the vibrations in the rocks beneath, and also indirectly through the deluging waves sent careering over the land from any seas in the range of the vibrations. Whenever the shakings of the continent extended beneath the ocean, these deluges from earthquakes of Laramide origin would have been destructive over all the coasts of a hemisphere. As land was mostly low at the time, the earthquake waves may have made their marches inland for hundreds of miles, and have left alive only the smaller animal species and the vegetation. This sweeping from the world of so large a part of its life, and especially that of Mesozoic characteristics, was a much-needed preparation for the era of the "Reign of Mammals." It was an opportunity for the "survival of the fittest " on a grand scale ; that is, the survival of those species that could withstand the special causes of destruction, and of the many that were out of harm's way. The exterminations were the removals of hindrances to progress. The survival of the fittest and of the lucky ones, while not directly species-making, was the origin of new associations in continental and oceanic life ; that is, of new faunas and new floras over the world, in which, under the modified geographical and physical conditions, the elements existed for further change and progress. IV. CENOZOIC TIME. It has been observed that, before the close of Mesozoic time, the medieval features of the era were already passing away. The Cycads had mostly given place to the Sassafras, Tulip tree, Willow, Maple, Oak, and Palm ; the ancient type of Ganoids, to Salmon, Perch, and Herring ; and the Corals, Echini, and Mollusks had close relations to those of existing seas, though of extinct species. But, notwithstanding these changes, the Mesozoic aspect continued to the end. Even the little Mammals, which appeared among the Reptiles, bore the mark of the age, for they approximated to the oviparous Reptiles and Birds, in being themselves either semioviparous or oviparous ; that is, either Marsupials or Monotremes. But with the opening of the new era, the Mammals in their turn became the dominant race. Types much like those of the age of Man were multi- plied among them, in all departments of nature. As the era advanced, the first of the species now living appeared, a few among multitudes that became extinct ; and afterward a larger proportion ; and, before it closed, nearly all kinds of life, excepting Mammals, were identical with those of the present era. As the Paleozoic or ancient life was followed by the Mesozoic or Medieval, so now there was as marked a change to the Cenozoic or recent life and world. Cenozoic time embraces two eras : I. The TERTIARY, or era of Mammals. II. The QUATERNARY, or era of Man. These eras, like consecutive eras in preceding time, were continuous in life through both the vegetable and animal kingdoms, and it is not proved that Man, the most characteristic feature of the Quaternary, was not in existence before the close of the Tertiary. But one of the grandest and most sweeping catastrophic epochs intervened between the two, the Glacial, .and so separated them, although the destructive influence of this epoch did not extend over tropical regions, except in the vicinity of lofty mountains. TERTIARY ERA. The Mammals of the Tertiary era are all extinct ; and the proportion of living Invertebrates, the Protozoans excluded, varies from none in the earlier part of the era to 95 per cent in the later part. The Early and Middle Quaternary Mammals are largely extinct, but the Invertebrates and Plants are existing species. The Later Quaternary or Recent animals and plants are of existing species, except those that have become extinct through the agency of man. 880 HISTORICAL GEOLOGY. GENERAL SUBDIVISIONS. The subdivisions of the Tertiary in general use were introduced by Lyell in the first edition of his Geology. They were based by him primarily on his own geological investigations in England and Europe, and on those of the French conchologist, Deshayes, who was already familiar with the fossil species of the Paris Basin. The proportion of living to extinct species was accepted as the distinctive character of the subdivisions. These subdivisions, and the proportions now adopted for the approximate limits, are as follows : 1. EOCENE period (from ^d>s, dawn, and KCUVO?, recent) : no species, or less than 5 per cent living. 2. MIOCENE period (from //.eiW, less, and KCUVOS) : 20 to 40 per cent living. 3. PLIOCENE period (from TrActW, more, and KCUI/OS) : more than half the species living. The Miocene and Pliocene are sometimes united under the name NEOCENE (from j/eos, new, and /ui/os), especially when the divisions are not well differ- entiated. The term Oligocene (from oAtyos, few, and KCUI/OS) is sometimes used for a fourth division, consisting of the upper part of the Eocene and the lower part of what had been referred to the Miocene. The term Oligocene was proposed by Beyrich, of Berlin, in 1855. In 1864, Homes,, of Vienna, proposed the term Palaeogene for the combined Eocene and Oligocene, and Neogene for the Miocene and Pliocene ; Eogene has also been used in place of Palaeogene. Further, the Lower Eocene has also received the separate name of Paleocene. J. W. Dawson adopted, in 1889, the term Orthrocene for the Lower Eocene, Nummulitic for the Middle, and Proicene for the Upper or (as he says) that of the Vicksburg Epoch. On the geological map published in 1884 by the U. S. Geological Survey, Eocene includes the Eocene and Oligocene, and Neocene the Miocene and Pliocene. In 1887, Heilprin proposed the substitution of Eogene, Metagene, and Neogene, severally, for Eocene + Oligocene, Miocene, and Pliocene + Quaternary. The name Tertiary is a relic of early geological science. When introduced, it was preceded in the system by Primary and Secondary. The first of these terms was thrown out when the crystalline rocks so called were proved to belong to no particular age, though not without an ineffectual attempt to substitute for it Paleozoic; and the second, after use for a while under a restricted signification, has given way to Mesozoic. Tertiary holds its place, simply because of the convenience of continuing an accepted name. Neo- zoic is sometimes used in place of Tertiary, while it is also occasionally made a substitute for the whole Cenozoic. It was originally proposed by Edward Forbes to comprise both the Mesozoic and Cenozoic. NORTH AMERICA. GENERAL GEOGRAPHICAL FEATURES OF THE TERTIARY ERA. It has been shown that the deposition of the Laramie beds and the up- turning which followed left the great interior of North America emerged. The Cretaceous sea, which had covered the Western Continental Interior and the Rocky Summit region from Mexico to the Arctic coast, was gone, excepting; CENOZOIC TIME TERTIARY. 881 a large bay on the Arctic shores, and an extended " Gulf of Mexico " at its southern limit. Isolated salt lakes probably remained for a while over the Interior, of which Great Salt Lake of Utah is the last survivor; but no marine Tertiary strata found in and about them are known to exist. The submerged portions of the continent, or the areas of marine rock making, were therefore confined to the borders of the continent, the Atlantic border, the Gulf border, and the Pacific border. This general condition of the continent during the early Tertiary is represented on the accompanying map, Fig. 1468. 1468. Map of North America showing the parts under water in the Tertiary Era ; the vertically -lined is the Eocene ; the horizontally -lined, the Miocene or Miocene and Pliocene ; the cross-lined, the Eocene and later Tertiary. It is observed on the map that the condition of the Atlantic border was much like that of the Cretaceous period ; that Florida was under water, as then, and that the Mississippi bay was scarcely diminished in extent during the time of greatest submergence. The portions of the Tertiary area which are lined vertically are those of the Eocene beds, and those lined horizontally, of the Miocene or Mio- cene and Pliocene. The map thus indicates the fact that along the Atlantic coast region the sea had nearly the same limit through both the Eocene and Miocene periods ; but that on the Gulf border a great retreat of the waters took place before the beginning of the Miocene. On the Atlantic border northeast of New Jersey, Tertiary beds have been identified by fossils only on Martha's Vineyard; and,. doubtfully, through shells brought up by the dredge, on St. George's Shoal, east of Cape Cod, DANA'S MANUAL 56 882 HISTORICAL GEOLOGY. and at one place on the Banks of Newfoundland. Their absence from the coast region in the higher latitude may be owing, as generally believed, to the present submergence of the border on which such beds were deposited. But the existence, for the most part, of rapidly deepening waters north of Newfoundland, and the denuding power of the waves of the open ocean may have been the effective cause along much of the coast. Although the ocean had been excluded from the Continental Interior at the close of the Cretaceous period, rock-making was still carried forward over much of its area by means of vast freshwater lakes. These lakes had their Fishes and other aquatic life, and their borders were frequented by various ^animals of the land, including Mammals of many species, with various small Reptiles, and the remains of these species abound in the lacustrine deposits. The freshwater Tertiary formations have consequently an importance not inferior to that of the marine beds. The great lakes of the earlier Tertiary the Eocene were situated in the Rocky Summit region, within the United States, mostly over the area of the Laramide mountain system. One Eocene lake, the Wasatch (W on the map), covered a large region north of the Uinta Mountains, between the parallels of 40 and 44, including parts of Utah, Wyoming, and a portion of northwestern Colorado; and as the earlier Wasatch Lake narrowed its limits in the later Eocene, it became the Bridger Lake. The " Green River basin " was part of the Wasatch. Another, the Uinta Lake (U), lay south of the Uinta Mountains, chiefly within the boundaries of Utah. Another smaller lake, the Puerco (P), was situated in the northern part of New Mexico, and extended across the border into Colorado. Two others, of small size, were situated in the region of the Great Basin west of Great Salt Lake. The lacustrine beds of Wasatch Lake occupy a plateau region about 6500 feet (6000 to 7000) above the 'sea level. The height of the village of Green River, within the former, above tide level, is 6140 feet ; of Bridger, 6780 feet ; of Wasatch, 6789 feet. Nearly all the later Tertiary lake basins lie either to the east or west of the Summit region, over Nebraska and the adjoining states on the eastern slope of the Rocky Mountains, or between nearly the same parallels but farther west ; part of them in the Oregon and Nevada portions of the Great Basin region. The extent of the Eocene lakes over the Summit region is regarded as evidence that the general mass of the mountains at the time stood but little above the sea level. The great thickness which the beds attained in the course of the Eocene is proof that the areas were undergoing a slow subsidence, keeping pace with the deposition, while their borders were essentially stable ; and that the position of the area of maximum subsidence changed in the course of the Eocene period. Further, the position and great extent of the Miocene lakes, covering a large part of the eastern slope of the mountains, are evidence that the elevation which took place at the close of the Eocene, draining the lake basin, was small. All the land of the Tertiary continent had its working streams and CENOZOIC TIME TERTIARY. 883 streamlets, denuding, transporting, making alluvial deposits, and carrying sediments to the seashores; and the whole surface was well populated, beyond doubt, by Mammals, Birds, and inferior terrestrial life. The moun- tains of the Appalachian System and its bordering regions on the east, west, and south contributed material for the marine Tertiary beds of the Atlantic and Gulf borders; the weakly consolidated beds of the recently made Laramide mountain ranges afforded the same more abundantly for the thick deposits of the vast freshwater lakes about the summit of the Rocky Mountains and over its eastern slopes; and the Sierra Nevada and other ranges of the western slopes were a source of supply for other lakes and for the marine Tertiary of the Pacific border. But notwithstanding the work of rivers and other agencies, there have not been found, up to 1894, over the eastern half of the continent away from the sea border, any recognizable fossil-bearing, lacustrine Tertiary deposits, excepting over small spots near the center of the state of Vermont. In the western half of the continent, the only fluvial beds recognized as Tertiary, by means of fossils, are those of the auriferous gravels of the Sierra Nevada. Nothing of Tertiary origin has yet been identified in or about the basin of Hudson Bay, or those of the Great Lakes, or in limestone caverns of the Mississippi valley and elsewhere, to prove that these basins and caverns were in existence during Tertiary time. They may have existed, but the proof is wanting. This work is indebted for the preceding Tertiary map of North America to G. D. Harris, who has prepared it from earlier maps and publications, from unpublished records of the U. S. Geological Survey, and to a considerable extent also from his own personal study of the marine Tertiary along the Atlantic and Gulf borders. Further, the subdi- visions of the eastern Tertiary adopted beyond, and the remarks on the distribution of the beds, are partly from his manuscript notes. In addition, he has revised the pages on the Invertebrate paleontology, of the same region ; and part of its illustrations are from his work on the Tertiary Paleontology of Texas. A list of earlier publications and a review of the facts and of the question of equivalency may be found in the U. S. Gr. S. Bulletin, No. 83, by W. B. Clarke, on the- Correlation of the Eocene Tertiary, 1891, and in the U. S. G. 8. Bulletin, No. 84, on the Correlation of the Neocene, by William H. Ball and G. D. Harris, 1892. SUBDIVISIONS. The periods of the Tertiary era proposed by Lyell are the basis of the American subdivisions, namely : (1) EOCENE, (2) MIOCENE, (3) PLIOCENE. To these are added by some, OLIGOCENE, corresponding in age to the Euro- pean Oligocene. NEOCENE is also sometimes used for the Miocene and Pliocene. The marine and lacustrine formations are independent in fossils, and besides are nowhere interstratified, and hence it is not possible to make out their precise equivalents. As regards the lacustrine beds, even the division into periods is based largely on facts from Europe. Moreover, the species of the marine Tertiary of the Atlantic and Pacific borders are almost wholly 884 HISTORICAL GEOLOGY. different ; and besides, those of the latter thus far make but one group for the Eocene, and one for the Miocene. For these reasons, the three regions, the Atlantic and Gulf borders, the Pacific border, and the Lacustrine areas, are independent in their subdivisions and cannot be satisfactorily correlated. They are brought together, however, in the following table, to exhibit the general relations of the subdivisions, and nothing more. It is not yet known in all cases what subdivisions of the Eocene formations recognized on the coast are equivalents of the Lower, Middle, and Upper Tertiary in the Continental Interior. TABLE OF APPROXIMATE EQUIVALENCY OF THE SUBDIVISIONS. Atlantic and Gulf borders Lacustrine areas Pacific border Foreign Pliocene Floridian Blanco Palo Duro Pliocene Pliocene Miocene Yorktown Chipola Chattahoochee Loup Fork John Day White River Miocene Tortonian Aquitanian Eocene Upper, Vicksburg Uinta Tongrian Ligurian r Jackson Middle \ Claiborne t Lower Claiborne Bridger Wind Eiver Tejon Parisian, or Calcaire Grossier ( Lignitic L wer 1 Midway Wasatch Puerco Suessonian Cernaysian a. MARINE TERTIARY OF THE ATLANTIC AND GULP BORDERS. 3. Pliocene period. FLORIDIAN EPOCH. Floridian of Heilprin, as modified by Dall. Merced group of the peninsula of San Francisco, of A. C. Lawson. 2. Miocene period. 3. YORKTOWN EPOCH. So named from Yorktown, Va., Dana's Geol, 1863. Chesapeake of Darton and Dall, 1891. 2. CHIPOLA EPOCH. Kepresented by the Chipola group of Burns, occurring along the Chipola River, Florida. 1. CHATTAHOOCHEE EPOCH. Chattahoochee of Langdon, named from typical exposures on the Chattahoochee Eiver in southwest Georgia and northwest Florida. 1. Eocene period. 6. VICKSBURG EPOCH. Vicksburg of Conrad ; named from beds at Vicksburg, Miss. 5. JACKSON EPOCH. Jackson of Conrad, exposed near Jackson,, Miss. CENOZOIC TIME TERTIARY. 885 4. CLAIBORNE EPOCH. Upper part of Claiborne of Conrad, oc- curring along the Alabama and Tombigbee rivers (Langdon), and in Arkansas. 3. LOWER CLAIBORNE EPOCH. Part of the Claiborne of Conrad, separated here by Harris; occurs in Alabama, Georgia, and South Carolina, and includes the Buhrstone of Tuomey and Lyell, and the Siliceous and Calcareous Claiborne of Mississippi. 2. LIGNITIC EPOCH. Represented by the Lignitic beds, in part, of Conrad and Hilgard, including the beds between the Buhrstone and the Matthews Landing clays, as restricted by Harris ; La Grange group, in part, of Safford ; Eolignitic, in part, of Heilprin. 1. MIDWAY EPOCH. Part of the Lignitic of Conrad, and of Smith and Johnson ; represented by the Calcareous beds near Midway, and the Matthews Landing clays, on the Alabama River. 6. MARINE TERTIARY OF THE PACIFIC BORDER. 3. Pliocene period. Represented by local deposits in California, Oregon, and Washington. 2. Miocene period. Represented by deposits in the coast region of California, which partly constitute the Coast Range at Astoria, Oregon, on the Columbia River, and also in Washington, to the north. 1. Eocene period. Represented by the Tejon group of J. D. Whitney (1869), named from the locality near Fort Tejon, Kern County, Cal. ; beds occur es- pecially along the east side of the Coast Range, near Astoria, Oregon. c. LACUSTRINE TERTIARY. 3. Pliocene period. 2. Blanco group of Cummins and Cope (1892), occurring at Blanco Canon, Crosby County, Tex., and extending northward along the Staked Plains beyond Red River. 1. Palo Duro beds of Scott ; Good-night beds of Cummins ; observed near the Canon of Palo Duro in Texas, and also in northern Kansas. 2. Miocene period. 3. UPPER MIOCENE. Loup Fork group of Meek and Hayden. 2. Loup Fork beds: On Loup Fork of Platte River in central Nebraska, but extending southward interruptedly to Mexico, and occurring in New Mexico on the Rio Grande, Gila, and San Fran- cisco rivers. Pliocene and Pliohippus beds of Marsh. 886 HISTORICAL GEOLOGY. 1. Deep River beds, the Cyclopidius beds of Scott, in the Deep River (or Deep Creek) region, which are overlaid by beds with Loup Fork fossils. Ticlioleptus beds of Cope, but not those so named of Wyoming and Oregon. 2. MIDDLE MIOCENE. Miohippus beds and John Day beds of Marsh (1877), occurring on John Day River, Oregon. 1. LOWER MIOCENE. White River beds of Hayden (1857) ; Oligocene of Scott. 3. Protoceras beds of Wortman, of the White Eiver region. 2. Oreodon beds of Marsh (1877), in the White River basin. 1. Titanotherium beds of Hayden (1857, 1869), in the White Eiver region on the Mobrara, and in Dakota and Colorado. Bronto- therium beds of Marsh. 1. Eocene period. 3. UPPER EOCENE. 4. Uinta group of Marsh (1871), and of King (1878), lying to the south of the Uinta Mountains in Utah (U on the map, page 881). Diplacodon beds of Marsh (1877) ; includes the Brown's Park group of Powell (1876). The Florissant .group of South Park, Col. The Amyzon beds of Elko and Osino, Nev., are referred to the top of the Uinta or base of the Miocene. 2. MIDDLE EOCENE. 3. Bridger group of Hayden (1869), named from Fort Bridger, Wyoming, represented to the north of the Uinta Mountains over- lying the Wasatch beds. Dinoceras beds of Marsh. Green River group of Hayden (1869) is included ; probably also the Washakie group of King (1878). The Wind River group of Hayden (1861) has been referred to the bottom of the Bridger by Scott and Osborn, and made the equivalent of the Green River group ; but to the top of the Wasatch by Cope. 1. LOWER EOCENE. 2. Wasatch group of Hayden (1870), covering parts of Utah, Wyoming, and Colorado. Coryphodon beds of Marsh. Vermilion group of King. Bitter Creek group of Powell. 1. Puerco group of Cope (1875), named from Puerco River, New Mexico, occupying a basin extending from northern New Mexico into southern Colorado (P, map). Lower Wasatch of Marsh. ROCKS KINDS AND DISTRIBUTION. The beds, especially the marine, commonly vary much in character from mile to mile. Instead of great strata of almost continental extent and uniformity, as in the Silurian, there is the diversity which exists among the modern formations of the seacoast. But yet such diversity is not CENOZOIC TIME TERTIARY. 887 universal, for in some regions the sands from shells and corals were made into hard limestones, as they are now, and over areas of great extent. Moreover, firm shales and sandstones occur that are like those of early time. Besides, there are thick beds of greensand, like those of the Cretaceous formation in constitution, and equally valuable as a fertilizer. There are also beds of coal or lignite associated with some of the deposits. Beds of siliceous organisms, Diatoms, Radiolarians, and Sponge spicules r have sometimes much thickness, and are occasionally partly consolidated into opal. The rocks of the lacustrine and terrestrial deposits are generally fine- grained, and either feebly indurated sandstones, soft straticulate clays passing into shales, or soft fragile limestones of fine grain; but these soft kinds graduate into harder and sometimes into coarser varieties. They have derived their great thickness in the usual way; that is, through a gradual subsidence attending the deposition from waters of the region. On the coast of Florida, some beds have been converted partially into phosphates (or phosphatized) , by water filtrating through overlying guano deposits. In the Rocky Mountain region and over the Pacific slope occur deposits, sometimes hundreds or thousands of feet thick, made of volcanic ashes. There are also coarse volcanic conglomerates or breccia. The volcanic beds sometimes cover the stumps of many successive growths of forests (page 135) ; and the finer kinds occasionally contain remains of the Beetles, Butterflies, and other Insects of the period. Lignite beds also occur locally over the country. One of the most noted of them is that of Brandon, Vt., which is probably of Eocene origin. It is associated with a bed of limonite. Denudation was universal over the exposed continental surface, as in all past time, dissecting and degrading mountains, and making fluvial deposits as well as lacustrine. The Auriferous gravels of the western slope of the Sierra Nevada are largely fluvial deposits of Tertiary origin, as shown by J. D. Whitney in his Geological Report on California (1865), and much more fully in his Auriferous Gravels of the Sierra Nevada (1880). The plants found in the gravel beds indicate, according to Les- quereux, a Miocene and Pliocene age; but Whitney regards the formation as representing the whole of the Tertiary. It probably began in the Cre- taceous period. As Le Conte states, the detritus of the old gravels is in general exceptionally coarse, showing strong currents. 1. Sea-border Areas. I. EOCENE. Along the Atlantic and Gulf borders (see map, page 881), the Tertiary belt is very narrow and interrupted through New Jersey ; it is broader in Maryland and Virginia, and still broader in South Carolina. But the formation is best displayed on the Gulf border. The inner limit, or that against the Cretaceous in the Carolinas and the Gulf region, is over 100 miles 888 HISTORICAL GEOLOGY. from the seacoast ; and in the Mississippi valley then a great bay, as in the Cretaceous period it extends northward over 500 miles, covering on the east a broad portion of the state of Tennessee, and reaching into Illinois, and on the west, an eastern portion of Missouri and Arkansas. From Texas it extends southward into Mexico. The formation exposed to view from New Jersey through Virginia con- sists of sand-beds of different colors, including greensand or glauconitic beds, often shell-bearing, and is referred to the Lignitic Eocene. In South Caro- lina the exposure reaches nearly to the coast, and is more varied in its con- stitution. Along the inner margin occurs a stratum of Buhrstone, about 200 feet thick, a cellular siliceous rock, from which the shells have been dissolved away by siliceous waters ; and over this, to the eastward, occur calcareous beds with some greensand, the Santee beds of Tuomey, and the related Ashley and Cooper beds, or beds along the basins of the Ashley and Cooper rivers. On the Gulf border the belt averages 65 miles in width. 1. The Midway, the lowest member of the Eocene, was named thus after a landing on Alabama River, Wilcox County, Ala., by Smith and Johnson in 1887. It was regarded by them as a subdivision of the Lignitic ; it is made by Harris to include the Black Bluff and Matthews' 1 Landing beds, and given coordinate rank with the Lignitic ; the Clayton or Monterey beds of Langdon. It is distinguished from the Lignitic by (1) its fossil contents and (2) the off-shore character of its deposits. In the region of Red River and the Mississippi Embayment, marine fossils are often wanting, and the beds are more or less lignitic ; open sea deposits are found in southeast central Texas, central Arkansas, eastern Alabama and Georgia. No outcrops of this group have been recorded to the northeast of the last mentioned state. Total thickness, about 250'. 2. The term Lignitic was used by E. W. Hilgard (1860) for the Lower Eocene of Mis- sissippi, consisting partly of freshwater lignitic beds and partly of estuarine fossiliferous deposits. The name Lignitic formation had been still earlier used by Conrad ; and Eo- lignitic was proposed by Heilprin in 1884 ; Lignitic is used by Smith and Johnson (1887), to designate all Eocene deposits lying beneath the Buhrstone. The name has recently been restricted by Harris to the beds lying between the Buhrstone and the Matthews Land- ing clays, and is so employed here. The formation includes shallow-water depositions. Lignitic clay beds alternate with sands ; the latter are often cross-bedded ; huge bowlders or septaria-like concretions are locally very abundant. Animal remains are scarce or wanting in the deposits west of the Mississippi ; but in Alabama and to the northeast, in Maryland and Virginia, they are abundant in certain layers. Where most typically devel- oped (in Alabama) the various subdivisions have received the following names and estimates of thickness from Smith and Johnson : (1) Nanafalia, 200'; (2) Bell's Landing, 140'; (3) Wood's Bluff, 80'-85'; (4) Hatchetigbee, 175'; total, 600'. The Pamunkey formation (Darton), i.e. the Eocene deposits of Maryland and Vir- ginia, are referable to the Bell's Landing horizon. 3. The Lower Claiborne was so designated by Harris to distinguish it from the Claiborne proper. It is represented in South Carolina, Georgia, and Alabama by the Buhrstone of Tuomey and Lyell ; in Mississippi by the Siliceous and Calcareous Claiborne of Hilgard ; in Louisiana by the Lower Claiborne of Harris ; in Texas by the Timber Belt beds and the Lafayette beds in part, of Penrose ; in California by part of the Tejon group of Gabb and Whitney. Near the axis of the Mississippi Embayment this group is without marine fossils ; elsewhere, especially in its upper portion, it is often highly fossiliferous. In Ala- CENOZOIC TIME TERTIARY. 889 bama Smith and Johnson have assigned the following thicknesses to its various sub- divisions: Buhrstone, 300'; Lisbon beds, 50'; Ostrea sellceformis beds, about 65'; in all about 415'. 4. The Claiborne was named by Conrad from Claiborne, Ala. The typical develop- ment of this group is of very limited geographical extent, being confined to the drainage of the Alabama and Tombigbee rivers (Langdon) ; but in Arkansas at White Bluff on the Arkansas River and elsewhere, there are marly sands with a fauna showing Jackson affin- ities, though they are at present classed as uppermost Claiborne. The typical Claiborne bed is 16' thick ; the White Bluff bed over it, 20'. 5. The Jackson beds were so named by Conrad from typical exposures at Jackson, Miss. They are sometimes improperly classed with the Vicksburg, under the name of White Limestone. They occur on the Gulf slope east of the Sabine River. In Arkansas and probably in Mississippi they extend some distance up the Mississippi Embayment, overlapping Claiborne and Lignitic beds. They are clayey and lignitif erous in this region ; but to the east, in Alabama, become calcareous and constitute beds of impure limestone. Thickness over 50'. 6. The Vicksburg, named by Conrad from typical exposures at Vicksburg, Miss. This group is mainly composed of limestones, pure and impure, and like the Jackson is confined to the Gulf slope east of Sabine River ; and unlike the preceding groups, it is little influ- enced by the Mississippi Embayment. According to Langdon's figures its thickness varies from 150' to 210'. The Eed Bluff group of Hilgard is scarcely separable faunally from this. General Eemarks. Although it has been said that the Cretaceous ( Chico) and the Eocene (Tejori) deposits west of the Rocky intergrade without a perceptible break, their respective faunas indicate that there is a break somewhere. On the Atlantic and Gulf slopes there is abundant proof of a marked discordance, both faunal and stratigraphic, between the Cretaceous and Eocene Tertiary series. In the Mississippi Embayment, at least in eastern Arkansas, the earliest known Eocene beds pass up and over the Cretaceous, while in southwest Arkansas, Texas, Alabama, and Georgia, broad areas of Cretaceous are exposed ; in Maryland and Virginia, where lowest Eocene is wanting, Lignitic beds rest upon the Cretaceous. II. MIOCENE AND PLIOCENE, OR NEOCENE OF THE ATLANTIC AND GULF BORDERS. While dredgings from the Grand Bank of Newfoundland, as well as from St. George's Shoal, off the coast of Massachusetts, render it probable that later Tertiary deposits exist beneatn these shallow seas, the first distinct exposures found on the Atlantic coast are those of Martha's Vineyard at Gay Head and Chilmark, as recently proved through a study of the fossils by Dall (1894). The next is near the village of Bridgeport in New Jersey. These exhibit Miocene marls of black, yellow, and gray hues, with a thick- ness of from 12 to 15 feet. The sands, clays, and marls from the Artesian well at Atlantic City indicate that the thickness of the Miocene strata there is not less than 700 feet. These deposits are mainly, if not exclusively, of Upper or YorJctown Miocene age. In Maryland the escarpments along the western shore of Chesapeake Bay, and along the Patuxent and Potomac rivers, show Miocene beds of sand and clay, rarely indurated, and, at base, thick deposits of diatomaceous earth, amounting in. all to a thickness of 400 feet. In Virginia a similar series is exhibited along the river courses'; and in the region of Dismal Swamp younger beds of Pliocene age are reported. 890 HISTORICAL GEOLOGY. In North Carolina these deposits are much thinner than in Maryland and Virginia, and in South Carolina they usually occur in isolated basins or sinks in the subjacent Eocene or Cretaceous strata ; they often show a reworking or rearrangement of material, so that Miocene, Pliocene, and even Cretaceous- fossils occur in one and the same bed. The component materials are sand,, clay, and comminuted shells. There are deposits in Georgia of limestone, buhrstone, and conglomerates that belong to the older Miocene series, but their geographical extent is not. well determined. Florida presents the most complete section of American marine Miocene and Pliocene formations. Immediately above the Eocene along the Chatta- hoochee River occur beds of limestone, clay, and marl, the Chattahoochee group of Langdon, having a thickness of about 200 feet. Higher still are the fossiliferous Chipola sands, succeeded in turn by the Alum Bluff sands, 40 feet thick, containing few organic remains save lignite and plants. Above these occurs a gray marl having a Yorktown fauna 35 feet thick. These Miocene deposits occupy much of the northern portion of the state. To the south the Peace Creek lacustrine deposits and Caloosahatchie beds of Plio- cene or Pleistocene age are probably well developed, though their exact limits are not definitely determined. The Neocene beds of Mississippi as well as Alabama and Louisiana Grand Gulf group of Hilgard contain but few animal remains, and their horizon has been, and still is to some extent a matter of dispute ; but the labors of L. C. Johnson and Langdon in southeastern Mississippi, southern Alabama, and northwestern Florida tend to show that they should be corre- lated with the lower Miocene of the Floridian section. They are well devel- oped in Mississippi, and although concealed to the south, doubtless underlie the greater part of the state south of a line roughly drawn through Vicks- burg, Raymond, Byram, Brandon, Raleigh, and Waynesboro, or, in other words, south of the Vicksburg formation. Below and to the east these beds are clayey, lignitic, and gypsiferous ; above and to the west the aranaceous material predominates, and when indurated gives a rugged topography to- the region in which it occurs. No traces of similar deposits have been found in Tennessee or Arkansas ; but in Louisiana they occur resting upon the Vicksburg limestone and extending in a southwestern direction toward the Sabine River. Certain deposits of clay, lignite, and sandstone in Texas the Lafayette- beds of Penrose have been correlated with the Grand Gulf rocks of Missis- sippi ; but the presence of Lower Claiborne species although rare throughout much of their vertical range, renders it quite probable that all should be referred to the Eocene period. To the seaward marine Neocene beds are unknown at the surface ; yet borings from the Deep Well at Galves- ton show that at no great depth such deposits do occur with a thickness of 1500 feet or more. Many lacustrine deposits are found at the surface bearing; Vertebrate remains of a late Tertiary age. CENOZOIC TIME TERTIAEY. 891 The epochs of the marine Miocene, as defined from the formations of the Atlantic and Gulf borders, are as follows : 1. CHATTAHOOCHEE : so named by Langdon, from typical exposures on Chattahoochee River, southwest Georgia, and northwest Florida. Dall correlates with the Chattahoochee deposits the Hawthorn beds of central Florida, consisting of phospbatic oolyte, ferruginous gravel, and green clays, the Orthaulax bed and Tampa limestone at Tampa, the Altamaha grits of Georgia, and also the "typical Gfrand Gulf" of southern Alabama. The last- named deposits are placed at this horizon because they are ' ' analogous to and probably synchronous" with the Altamaha grits of Georgia, and are overlaid at Roberts, Escambia County, Fla. (according to Smith), by a bed containing Chipola fossils, as identified by Dall. The Chattahoochee fauna is closely related to the Miocene of West Indies, Jamaica, Trinidad, Haiti, Curac,oa, Panama, and Costa Rica (Dall). 2. CHIPOLA. : distinguished by Burns, and first named by him in manuscript as the Chipola formation from typical exposures on a river by that name in northwestern Florida. The lower member of the group, the Chipola sands, is famous for its vast number of fossil shells, nearly 400 species having been found at the type locality. This- remarkable faunal development is to the Miocene what the Claiborne fauna is to the Eocene ; both occur in slightly ferruginous sands about 16' thick, both appear to be very limited in areal extent, and both occur medially in their respective periods. The fauna of the Alum Bluff sands (Dall) immediately overlying the fossiliferous Chipola bed has not been carefully studied. All these older Miocene deposits are characterized by a warm-water or subtropical fauna (Dall). 3. YORKTOWN : named from Yorktown, Va., by Dana (1863). It is the time-equiva- lent of the Chesapeake group of Darton and Dall (1891). It includes the Miocene of the Atlantic slope as known to geologists prior to 1887. The section at Alum Bluff shows that this group lies above the Chipola. It is well developed in Duplin County, N. C., at Yorktown, and elsewhere in Virginia, and along the river courses in Maryland. Calvert Cliffs on the west shore of Chesapeake Bay exhibit three well-defined fossiliferous zones, named, in descending order, the St. Mary's, Jones Wharf, and Plum Point. Beds lower still in the series are found on the eastern shore of Maryland, and with these in New Jersey Dall finds traces of older Miocene fossils. It has been identified by its fossils on Martha's Vineyard by Dall. A modification of this fauna is found in the Galveston Deep Well, Tex., between depths of 2000' and 3000'. Since the publication of Gabb's work on the California Geological Survey the Miocene as well as Pliocene fossil remains of the Pacific slope have received little attention. As a rule the Miocene fossils are poorly preserved, and are often embedded in firm rock. Their general aspect indicates a horizon more nearly that of the Yorktown group than that of the older Miocene. In Georgia and Florida, where newest Eocene and oldest Miocene occur, there is a marked faunal break between the two, yet there are several species in common. In Maryland and Virginia, where Yorktown Miocene rests upon Lignitic Eocene, the break is complete, not one species being found common to the two. The upper, or Yorktown, Miocene was characterized by a fauna indicative of a temperature similar to that of to-day. The Ashley marl bed of South Carolina, containing phosphatic nodules with fossils- in them, which was referred by Tuomey doubtingly to the Eocene, affords Miocene- fossils (1894). Of marine Pliocene, there are the Floridian deposits of Heilprin as modi- fied by Dall (1892); the Pliocene of Tuomey (1848), excluding some Miocene beds as ; determined by the investigations of C. W. Johnson and Dall. To this period have been referred the Orange sand group of Safford (1856), occurring in Tennessee, the Orange sand of Hilgard (1860), in Mississippi and Tennessee, the Orange sand, or Lagrange 892 HISTORICAL GEOLOGY. .group, of Safford (1864), the Appomattox of McGee (1888), all of one formation, and now named by agreement the Lafayette j made by Hilgard, and in this work, a formation of the Glacial period. Marine deposits of this period are well developed along the Caloosa- hatchie River, south Florida. To the north, considerable areas are supposed to have been occupied by lakes having but slight elevations, and subject to occasional intrusions of the sea with its salt-water fauna ; hence the Peace Creek bone beds in Manatee County, and Alachua clays, in Alachua County, are found apparently interstratified with marine Pliocene deposits (Dall, U. 8. G. 8. Bulletin, No. 84). The Mammals include a considerable number of Eocene, Quaternary, and Pliocene species, and the beds are supposed to be Quaternary in accumulation. Dall reports that the Miocene group of Gay Head, Martha's Vineyard, is overlaid by l^eds affording Pliocene fossils (1894). MIOCENE AND PLIOCENE OF THE PACIFIC COAST. Along Carrizo Creek, east of the coastal range of mountains in southern California, there is a bank or terrace, sometimes composed of fossil shells in its upper part, that has been referred to the Miocene Tertiary by Conrad and to the Pliocene by Gabb. The sandstones and shales of the Santa Suzanna, Santa Monica, and Santa Inez ranges are mainly referable to the Miocene ; the conglomer- ates and sandstones about the base of the San Gabriel range can only be classed as Neocene. Resting on the granitic axis of Santa Lucia Mountains are highly metamorphosed Neocene (Miocene ?) sandstones ; stratigraphically above are thick deposits of bituminous shales, "which toward the southeast are overlaid by soft, sometimes calcareous, sandstone, having ;a thickness of over 1000', and referable to the Miocene series on paleontological evidence. Sandstones and bituminous slates of this age have been described from the Sierra de Salina, Gavilian, Santa Cruz, and Mount Diablo ranges. In the region of Mount Diablo Turner finds the Miocene series made up of coarse gray sandstone containing the large Ostrea titan, and conglomerates with pebbles of rhyolyte, quartz, and metamorphic rock. The Pliocene beds contain marine fossils, silicified wood, hornblende-andesyte tufa, and pebbles. North of the Golden Gate several fossiliferous Miocene deposits have been recorded, but their characters and limits are unknown. Along the foothills of the Sierra Nevada, especially in the vicinity of Ocoya Creek, there are Miocene beds of fine sand, coarse sand, conglomerates, fragments of pumicestone, ferruginous fossiliferous gravel, and clay nodules, in all 160' thick. Farther to the north, the lone formation of Lindgren, best developed in Amador and Calaveras counties, is composed of (1) 100' of clay rock, (2) 100' of sandstone, (3) 860' or more of white clay and sand beds containing coal seams. In Oregon, Miocene sandstones and shales occur at Astoria, and others, presumably of the same age, at Port Orford, Cape Blanco, and near Yaquina Bay. They are perhaps a continuation of the bituminous shales and sandstones of California. From 1 to 3 miles -east of Eugene City, Dall has noted a Miocene sandstone 37' thick. Condon states that the backbone of the Coast Range consists of argillaceous Miocene shale similar to that at Astoria ; stratigraphically above are the fossiliferous Solen beds of Condon, also of Miocene age ; on the flanks of the highlands there are lacustrine deposits containing some Equus bed (Quaternary) fossils. In Washington, the Astoria clay-shales are reported from near Bruceport, and at vari- ous points on Shoal water Bay. Other outcrops of the same formation are known from Vancouver Islands and Alaska. The Pliocene Merced group of Lawson (Bull. Geol. Univ. Cal., i., 142, 1893), on the coast of the San Francisco peninsula, south of the Golden Gate, is described as having a thickness of 5834'. A cliff consisting of the beds, 720' high, extends from Lake Merced, near San Francisco, to Mussel Rock, about 8 miles south of Point Lobos. The basal bed contains some carbonized wood and leaves. Some of the fossils were described by J. G. Cooper in 1888, and a list of others, determined by Dall, is given in Lawson's paper. Delta material in the great valley of California at San Benito also is referred by him to the Pliocene. CENOZOIC TIME TERTIARY. 893 Miocene and Pliocene beds have been identified in Alaska, and descriptions and a map- showing their distribution, by W. H. Pall, are contained in his Bulletin 84 of the U* S. G. S., 1892. 2. Lacustrine Deposits of the Continental Interior and Pacific Slope. I. EOCENE. The lacustrine Eocene areas are confined mostly to the summit region of the Rocky Mountains and its broad slopes, and are noted for the abundance of fossil vertebrates. The oldest, according to present knowledge, that of the Puerco basin, covers a large area in northwestern New Mexico, and extends northward into Colorado. The beds rest on the upturned Laramie, and are overlaid conformably by the Wasatch beds. The Wasatch basin (W on the map, Fig. 1468), also Lower Eocene, lies to the north of the Uinta Mountains, and east of the Wasatch range. Its original breadth was probably nearly 300 miles, and the extreme length from north to south perhaps 500 miles. The thickness of the beds near the Wasatch range is about 4000'. The Wasatch also occupies a basin extending from New Mexico northward, to the Uinta Mountains and the Big Horn basin in Wyoming. The beds also of the Cuchara basin of R. C. Hills are referred to the Wasatch Eocene. Two other basins, the Green River and Wind River, are situated to the north of the Uinta Mountains, and are intermediate in age between the Wasatch and Bridger. The Green River basin is situated mostly within Wyoming, and has an area of more than 5000 square miles. The beds consist of impure limestone below, and thin fissile calcareous shales above, in all 3000' to 4000', and are especially noted for their fossil Fishes and Insects. Fine views of the bluffs and of the " Bad Lands " of the Wasatch are given in King's 40th Parallel Report, on plates 13, 14, 15 ; and general views of the Green River basin, in Hayden's Report for 1872. The Manti beds of Cope (1880), occurring in Sevier and San Pete counties, Utah, are similar in character and fossils to those of the Green River basin. The Bridger basin of the Middle Eocene is situated between the meridians of 109 p W. and 1101 W., and for the most part north of the parallel of 41. Washakie basin of King (1878), which lies 60 miles farther east, and the Huerfano group of R. C. Hills (1888-1891), are of the same age. The latter lies to the east of the Front Range in Huerfano and Las Animas counties, southern Colorado. The Uinta lake basin (U, Fig. 1468), of the Upper Eocene, lies wholly to the south of the Uinta Mountains, and has now a level of about 10,000' above the sea. Its width from east to west is over 140 miles. The Amyzon beds, referred to the later part of the Eocene, occur in northeastern Nevada, in South Park, Col., and in central Oregon. They are probably intermediate between the Uinta and White River beds. The small Florissant basin is situated 8000' up in the mountains of southern Colorado. Its beds are largely made of volcanic earth, or tufa, and have become famous for their great numbers of fossil Insects and Spiders, and also for their Fishes, and for feathers and other remains of Birds, besides plant remains. II. MIOCENE. In the Miocene period the Eocene lakes of the Rocky Mountain region had mostly been drained through an increase in the elevation of the land or changes in its surface level ; but the mountain area still remained so low that even greater lakes then existed over what are now the eastern slopes of the mountains. They were situated in the region of the upper Missouri, and covered most of the state of Nebraska and a portion of Wyoming and Colorado, and extended from Nebraska southward. The area is over 350 miles in its maximum breadth, and has a height at the present time, through subse- quent elevation, of about 6000' to the west and 3000' to the east. The Earlier Miocene is that of the White River group. Its oldest deposits, the Titanotherium beds of Hay den, consist mainly of variegated clays, together with sand- stones and conglomerates, and have a thickness of 180' (J. B. Hatcher) ; above are the 894 HISTORICAL GEOLOGY. Oreodon beds of sandstones and clays, often nodulous, about 150', with 100' of overlying clays (Wortman) ; and above these the Protoceras beds, sandy below, but clayey above, 150', in all 480' thick (Wortman). In the region of these basins the strata, owing to erosion by rills and streams from occasional rains, stand in isolated earthworks or embankments, pyramids and spires, over the great plain, looking like a field of desolate ruins, parched and barren in the dry -climate. To this region was first applied the term " Mauvaises Terres," or Bad Lands. In Oregon, on John Day and Des Chutes rivers, near 120 W., is another lake-basin, the John Day basin (D, Fig. 1468), hardly 500 square miles in area. The Miohippus beds of Marsh, the upper portion, have afforded remains of Miocene Mammals, apparently of a little later date than the White River beds. Marsh correlates with the Oregon Miohippus beds the Protoceras beds of Wortman, stating that the latter contain the Oregon species Miohippus annectens Marsh ; and he further makes his Ammodon beds of the Miocene on the Atlantic border essentially of the same horizon. The Loup Fork Group, of the Upper Miocene, was so named from a river in Central Nebraska. The beds cover for the most part the Nebraska lake region (marked N on the map), and its extension southward to Texas, New Mexico, and Mexico. King gives the thickness in Wyoming as 2000'. To the eastward, on the White River, it is 150'. The Deep Creek beds of Montana, first made known by S. B. Grinnell and E. S. Dana (1876), or the Ticholeptus beds of Cope, are referred by W. B. Scott to the earlier part of the Loup Fork epoch. The basin is situated near Camp Baker, 50 miles east of Helena, along RICHMOND INFUSORIAL EARTH. a, Pinnularia peregrina; 6, c, Odontidium pinnulatum ; d, Grammatophora marina ; e, Spongiolithis appendiculata ; /", Melosira sulcata ; g, transverse view, id. ; h, Actinocyclus Ehren- bergii; *, Coscinodiscus apiculatus ; j, Triceratinm obtusum ; Jfc, Actinoptychus undulatus ; I, Dictyocha crux ; m, Dictyocha ; n, fragment of a segment of Actinoptychus senarius ; o, Navicula ; p, fragment of Coscinodiscus gigas. CENOZOIC TIME TERTIARY. 895 Deep River Valley (or Deep Creek) and other valleys of the vicinity. The beds are hard cream-colored clays, overlaid by loose beds of coarse and fine material of the Loup Fork horizon. Cope's Ticholeptus beds of Cotton wood Creek, in Oregon, according to Scott, are probably of the Loup Fork horizon ; but those of western Nebraska he refers to the White River group. The Pah- Ute Lake of King, named from a mountain ridge in Nevada, was described by him as extending from the Columbia River, through Oregon and Nevada, into Cali- fornia an improbable range for one lake. He named its beds the Truckee Miocene. They include, in Nevada, sands, grits, volcanic tufa, and infusorial deposits, the last 250' to 300' thick. Diller reports the Upper Sacramento Valley as the area of a great Miocene lake, 'covering part of the northern end of the Sierra Nevada. III. PLIOCENE. The Blanco beds of Cummins and Cope, on the Staked Plains of western Texas, consist at Blanco Canon of beds of clays and sands, in all 150' to 200' thick. The underlying beds are referred to the Triassic. The beds extend northward beyond Red River. LIFE. PLANTS. 1. Protophytes. About 100 species of Diatoms have been described by Ehrenberg and Bailey, from the Infusorial stratum of Eich- mond, besides a few Polycystines and many sponge-spicules. Fig. 1469 repre- sents a portion of the Eichmond earth, as it appeared in the field view of Ehrenberg's microscope. This is an example of one of the many Infusorial earths of the era. 2. Angiosperms, Conifers, Palms. The lignitic beds in the lower part 1470, Quercus myrtifolia (?); 1471, Cinnamomum Mississippiense ; 1472, Calamopsia Danse; 1478, Fagus ferruginea (?); 1474, Carpolithes irregularia. 896 HISTORICAL GEOLOGY. 1475. of the Eocene of Mississippi, Arkansas, and elsewhere, have afforded large- numbers of leaves of plants; others have been obtained, together with a variety of nuts, from the bed of lignite at Brandon, Vt. The plants of these beds, some of which are here represented, are closely related to those of the present era. Fig. 1470 represents an oak leaf (Quercus myrtifolia) from Somerville, Tenn., the Lagrange group of Safford; Fig. 1471, leaf of a cinnamon (Cinnamomum Mississippiense) , from Mississippi, at Winston; Fig. 1472, a palm (Cala- mopsis Dance Lsqx.), from Mississippi, in Tippah, Lafayette, Calhoun ; Fig. 1473, nut of a beach (Fagus ferruginea (?)), from the Lagrange group of Tennes- see; Fig. 1474, fruit (Carpolithes irregularis Lsqx.), from the Brandon Lignite bed; Fig. 1475 (Carpo- lithes Brandonensis Lsqx.), the most abundant of the Brandon nuts, natural size. The kind of plant pro- ducing these two fruits is undetermined. Among the other Brandon fruits, Lesquereux recognized the Carpolithes Brandonesis. genera Qarya, Fagus, AristolocMa, Sapindus, Cinna- momum, Illicium, Carpinus, and Nyssa. (Am. Jour. Sc., xxxii., 355, 1861.) ANIMALS. Invertebrates. In the Eocene, among Protozoans, Rhizo- pods are very numerous in some of the beds. The coin-shaped fossils, Orbitoides, resembling Nummulites in form, abound in the Vicksburg beds, and the rock is often called the Orbitoides limestone; the common species, 0. Mantelli, is represented in Fig. 1494. Midway. Characteristic species of the Midway group are represented in Figs. 1476-1478 ; of the Lignitic group, in Figs. 1479-1481 ; and Eocene of the Lower Claiborne, in Figs. 1482-1484, 1487, 1488 ; of the Upper Clai- borne, in Figs. 1485, 1486, 1489 ; of the Vicksburg, in Figs. 1490-1496 ; of the Miocene, in Figs. 1497-1507 ; of the Pliocene, in Figs. 1508-1510. 1476 1476-1478. 1477 1478- EOCENE, MIDWAY GBOTTP. Fig. 1476, Enclimatocenas Ulrichi ; 1477, Volatilities rugatus ; 1478, V. limopsis. Fig. 1476, C. A. White ; 1477, 1478, Harris. CENOZOIC TIME TERTIARY. 897 1479. 1480. LIGNITIC GROUP. Fig. 1479, Ostrea compressirostra (x?) ; 1480, Dosiniopsis lenticularis, var. Meekii. Fig. 1479, Say ; 1480, Conrad. 1481-1486. 1483 1484 1482 LIGNITIC. Fig. 1481, Venericardia planicosta (x $). LOWER CLAIBORNE. Fig. 1482, Ostrea selteformis ; 1483, Pteropsis Conradi; 1484, Turritella nasuta. UPPER CLAIBORNE. Fig. 1485, Crassatella alta ; 1486, Turritella carinata. Figs. 1481-1483, 1485, 1486, Meek ; 1484, Harris. 1487 1489 LOWER CLAIBORNE. Fig. 1487, Belosepia ungula; 1488, Mesalia Claibornensia. UPPER CLAIBORNE. Fig. 1489, Caricella Claibornensis. Harris. DANA'S MANUAL 57 898 HISTORICAL GEOLOGY. 1490-1496. 1498 EOCENE. Vicksburg group. Fig. 1490, Pecten Poulsoni ; o, section of same ; 1491, Mortonia Rogers! ; 1492, Ostrea Georgiana (x$), Vicksburg (?) ; 1493, Area Mississippiensis ; 1494, Orbitoides Mantelli; 1495, Lyria costata ; 1496, Dentalium Mississippiense. Figs. 1490-1492, 1494, Meek ; 1493, 1495, 1496, Conrad. 1497 1497-1499. 1-198 1499 MIOCENE. CJiattahoochee group. Fig. 1497, Turritella Tampae (x f) ; 1498, Pyrazisinus campanulatus ; 1499, Cerithium Hillsboroense. From Ball. CENOZOIC TIME TERTIARY. 899 1600 1602 MIOCENE. Chipola group. Fig. 1500, Orthaulax Gabbi ; 1501, Turritella subgrundifera(x ) ; 1502, S trombus Aldrichl. From Ball. 1503-1505. 1503 1504 MIOCENE. ~ Yorktown group. Fig. 1503, Pecten Jeffersonius (x |); 1504, Ecphora quadricostata (x |); 1505, Striarca centenaria. T. Say, 1824. 900 HISTORICAL GEOLOGY. 1506 1506, 1507. 150T 1506 a MIOCENE. Figs. 1506, a, Crepidula costata ; 150T, Cyprsea Carolinensis. Meek. 1508 PLIOCENE. Floridian group. Fig. 1508, Area crassicosta ; 1509, Venus rugatina (x ); 1510, Arcoptera avicu- Iseformis (x ). Original. Insects. The Insects of the Florissant basin, described by Scudder, include species of all the grand divisions ; and hundreds of some of them. The number, thus far made out, according to this author, is of Orthopters, 24 ; Neuropters, 57 ; Hemipters, 220 ; Coleopters, over 400, of which 116 are 1511. 1512. INSECTS. Fig. 1511, Prodryas Persephone ; 1512, Tipula Carolinse. Scudder. Rhynchophora ; Dipters, 250 ; Lepidopters, 9 ; Hymenopters, about 235 species. Of the Dipters, 51 are Tipulidse, and one of these, two thirds of an inch in length, is represented in Fig. 1512, and one of the Butterflies, in Fig. CEXOZOIC TIME TERTIARY. 901 1511. Besides these, Scudder has made out 31 species of Arachnids or Spiders. He states that about a fourth of all the species at Florissant are ' Ants (Formicidae), and that by 1885 more than 4000 specimens of Ants had been brought from the beds. Of Aphides, or Plant-lice, an eighth of an inch long, or less, he has collected over 100 specimens, representing 32 species, and all but one showing well the wings. Two other localities, affording similar species, one on the crest of the Roan Mountains in western Colorado, and the second on the lower part of White River, at the Utah line, are supposed to be at least as rich as Florissant. Eocene Vertebrates. 1. Fishes. The remains of Ganoid fishes (genera Lepidosteus, Amia), and Teleosts, of the Perch, Herring, and other families, are abundant in the Green River shales, along with remains of Plants and Insects. The marine Tertiary beds of the Gulf and Atlantic borders, and especially of the Eocene, contain, in many places, the teeth of Sharks in great numbers ; three kinds are represented in the accompanying figures. Some of the triangular teeth of Carcharodon megalodon Ag. (resembling Fig. 1513), are six inches broad at base and six and a half long. 1513-1516. 1514 1516 TEETH OF SHARKS. Fig. 1513, Carcharodon angustidens ; 1514, Lamna elegans ; 1515, Notidanus primigenius. TESTUDINATE. Fig. 1516, Testudo brontops (x T z)- Figs. 1513-1515, Agassiz ; 1516, Marsh. 2. Reptiles. The Tertiary Reptiles include species of Crocodiles, among them, Crocodilus Elliotti Leidy, from South Carolina, and C. Squankensis of Marsh, from New Jersey ; of Snakes, of the genus Dinophis Marsh, from New Jersey, and of Boavus and Lithophis, from Fort Bridger, about 20 feet long; of Turtles, of the genera Testudo, Emys, etc., from the Atlantic border and the Rocky Mountain region. Fig. 1516 represents one of the largest of 902 HISTORICAL GEOLOGY. American Turtles, from the Lower Miocene, or White River beds, of Dakota, Testudo brontops of Marsh, which had a length of about two and two thirds feet. The Puerco beds have afforded a species of Champsosaurus (C. Sapo- nensis of Cope), a Laramie genus. A very small species of Crocodile has been reported from the White Eiver beds. 3. Birds. The Eocene and Miocene have afforded remains of species related to Waders, an Owl, Bubo leptosteus of Marsh, a bird near the Woodpeckers, some web-footed species allied to the Gannet ; and the Mio- cene, remains of a large Eagle, a Cormorant, and other birds. The Diatryma yigantea of Cope, from the early Eocene of New Mexico, was larger than the Ostrich. The Barornis regens of Marsh, from the Upper marl beds of Squankum, N. J., of the Eocene, had about the size and many of the charac- ters of the Ostrich. From the Florissant beds have been obtained a Plover and other species. 4. Mammals. The sea-border Tertiary of the continent has afforded remains of but few Mammals ; for seashores are not their ordinary resort except for aquatic kinds. The regions of the great lakes over the Rocky Mountain area, on the contrary, have been found to be literally Tertiary burial-grounds. They bear evidence that Mammals in great numbers, and of several successions of faunas, lived and died about these lakes, and by lacustrine agencies were buried. These ancient bone-beds remained almost unknown to science until the year 1847 ; and now, through the labors of explorers, and the works of Leidy, followed by the memoirs of Marsh, Cope, Scott, Osborn, and others, the number of known species far exceeds that of existing North American Mammals. These Mammals are, with rare exceptions, of the ordinary or placental type. The Marsupials, as in earlier time, were small species, re- lated to the Opossums ; and their remains are known from the Early Eocene onward. Eocene. The Eocene species comprise Herbivorous, or Ungulate, Car- nivorous, Insectivorous, and Rodent species, and also Quadrumana; and before the close of the period, Cetaceans, or Whales. The remains of Ungu- lates are most abundant, because such species frequent lake borders. They are related to the modern Tapir, Wild Boar, and Rhinoceros, yet only in a very general way, as these special types belong to a later period. The earliest of the Eocene species are remarkable for their prototype or primi- tive characteristics : (a) the legs being approximately equal ; (6) the feet five-toed and of typical form, the five toes similar, with the third or middle toe a little the longest ; (c) the carpal bones and the tarsal in vertical series with the following bones of the foot; (d) the teeth of the typical number, 44, that is, 11 in either ramus of each jaw, the 11 including 3 incisors, 1 canine, 4 premolars, and 3 molars ; (e) the molars of simple form, being usually tritubercular at summit, or trigonodont; (/) the head without armature of horns or tusks. CENOZOIC TIME TERTIARY. 903 Moreover, the types are generally comprehensive or intermediate kinds. The flesh-eaters are intermediate in their teeth and other characters between Carnivores and Insectivores, and have been referred by Cope to a separate group named Creodonts, from the Greek foi flesh and tooth. Another group has some of the features of the Tillodonts, Kodents, and Ungulates; and the Ungulates also have some of the characteristics of Carnivores or Quadrumana. The prototypic features are presented by species of the genera Phena- codus, Coryphodon, and many others. They are well illustrated, as pointed out by Cope, in the Phenacodus primcevus, described by him from a speci- men found in the Wasatch beds (Fig. 1517). Besides the primitive features of 44 teeth, of five similar toes to both fore and hind feet, of the carpal in series with the digits (Figs. 1517 a, 6), the feet were probably planti- grade, the foot striking the ground with the whole sole, instead of being 1517. MAMMAL. Phenacodus primajvu Cope. raised on the toes (digitigrade). The animal is supposed to have been omnivorous, from its teeth. The length of the body was about four feet. The Creodonts (prototypic Carnivores) of the Puerco beds also are described by Cope as plantigrade species. These characters are also well exhibited, as shown by Marsh, in species of Coryphodon from the Wasatch group. A restoration of Coryphodon hamatus of Marsh is represented in Fig. 1518, and the fore feet and hind feet in Figs. 1518 a, 6. The length of the body was six feet. The special prototypic features of the feet and limbs are manifest, after the above state- ments, without special remarks. The animal was digitigrade, and had short, nearly equal toes, a type of foot which is represented also in the modern Elephant. An early genus in the line of the Tapir is Systemodon of Cope, represented by S. tapirinus from the Wasatch. Besides other primitive features, it has the teeth in a continuous series, there being no interval (diastema) between the canines and the premolars. 904 HISTORICAL GEOLOGY. The Tillodonts of Marsh, which range from the Puerco through the Bridger Eocene, fail of prototypic characters in having less than the normal 1518. Fig. 1518, Restoration of Coryphodon hamatus (x 5 ^) ; a, fore foot; 6, hind foot (x ). Marsh. number of incisors, with one of the pairs much elongated like those of a Beaver and other Rodents, as shown in the figures of Tillotherium fodiens of Marsh. The name, from TiAAo>, bite, alludes to the long incisors. Psitta- 1519-1523. 1520 1519 Figs. 1519, Tillotherium fodiens, top view, with form of brain cavity (x ) ; 1520, same, skull and lower jaw ; 1521 a, 6, same, ungual phalanx or claw, front and side view ; 1522, T. latidens, last upper molar (x f) ; 1523, Anchippodus minor, lower molar (x |). All from Marsh. cotherium of Cope is a genus of the group from the Puerco beds ; Anchippodus of Leidy, from the Bridger group and the New Jersey Eocene ; and Tillo- CENOZOIC TIME TERTIARY. 905 1527 therium and Stylinodon of Marsh, from the Bridger beds. Figs. 1519-1521 are of Tillotherium fodiens; 1522, of T. latidens; and 1523, of Anchippodus from Marsh. Examples of later specializations are here illustrated (Figs. 1524-1527), in Tapir-like species ] of the genera Eohippus and Orohippus of Marsh, the former from the Wasatch beds, and the latter from the Bridger. In Eohippus the fore feet (Fig. 1524) have all the five toes represented, but the first toe is already reduced to a " splint-bone " in its metacarpal, 1525 while the hind feet (Fig. 1525) have lost wholly the first toe with the metatarsal above, and the fifth toe is reduced to a splint- bone. In the later Orohippus the first toe of the fore foot with its metacarpal (Fig. 1526) 1524-1527. 1526 8 Fig. 1524, Eohippus pernix, left fore foot ; 1525, id. left hind foot ; 1526, Orohippus agilis, fore foot ; 1527, id. hind foot (all x |). Marsh. s wholly wanting, and the first and fifth of the hind foot (Fig. 1527) are wanting. Fig. 1526 affords an illustration also of the change in the relative positions of the carpals of most Mammals (and also usually of the tarsals) from that of vertical series (the prototypic position) to that in which the bones alternate with one another (Fig. 1526), so as to give the joint greater strength and safety. This change, with others of like import, began even in the Eocene. In addition, the metacarpals are much elongated. 1528. Tapirus Indicus, the modern Malayan Tapir. 1 On account of the frequent references in the remarks on Tertiary Mammals to the Tapir, a figure of a modern species is here introduced. It shows its general form, short legs, and elongate nose. 906 HISTORICAL GEOLOGY. From the Puerco and Wasatch beds come the earliest of the Quadrumana. Fig. 1529 represents the skull of one of the species, Anaptomorphus homun- culus Cope, from the Wasatch beds of the Big Horn Basin, of Wyoming. 1629. Anaptomorphus homunculus ; a, cranium, from above ; 6, same, from below, enlarged. Cope. Other Wasatch species include Creodonts of several genera, Insectivores. and the earliest of true Kodents. There were also in the Wasatch beds, and others equivalent, the first of Artiodactyl Ungulates, the 4-toed Pantolestes brachystomus of Cope, and Homacodon prisons of Marsh ; named Artiodactyls (and also Paridigitates) because the four toes are in pairs, the third and fourth being equal, and also the second and fifth if present. Examples are shown in Fig. 1538. The two pairs are present in the Hog, Hippopotamus, etc. ; the 1530. Eestoration of Tinoceras ingens of Marsh (x 5^). CENOZOIC TIME TERTIARY. 907 1531. single pair (often with rudiments of the other), in the Cainel, Stag, Ox, etc. Another Artiodactyl of the same horizon is the Eoliyus distans of Marsh, having Suilline or hog-like characteristics. The Bridger Eocene is remarkable for the remains of Dinocerata, animals of Elephantine dimensions, having elongate canines, and two or three pairs of bony prominences or horns on the head. Fig. 1530 represents the Tinoceras ingens of Marsh, an animal 12 feet in length. They were successors to the Coryphodons of the Wasatch. The prominences referred to are situated severally on the snout, the cheeks, and the forehead. Marsh observes that part, if not all of them, were horn-cores or bases of horns ; and that those that were not so must have been covered with the hide, as in the Giraffe. While thus armed to excess, and probably of great strength, the very small brain shows that they were extremely low in intelligence. The earliest species are : Tinoceras anceps of Marsh, described in October, 1872 (his Titanotherium anceps of 1871, found in 1870) ; Uintatherium robustum of Leidy, August, 1872; and Tinoceras grandis and Dinoceras mirabilis of Marsh, October, 1872. Uintatherium Leidyanum of Osborn (1878, 1881) has very prominent horn- cores and is from Dry Creek, Wyoming. Uintatherium has 36 teeth, Dinoceras and Tinoceras 34. The Bridger beds have afforded, among species related to the Tapir, the genus Helaletes of Marsh, having the teeth 44 in number and in contact, which are prototypic char- acters: also species of Hyrachyus and Palceosyops of Leidy, which are es- pecially common in the beds. Fig. 1531 is a restoration, by C. Earle, of Palceosyops paludosus of Leidy, an animal about six feet in length. There are also in the Bridger beds remains of Quadrumana, Creodonts, and Bats, as well as Eodents and Insectivores. The Uinta group, the last division of the Eocene, has afforded new Tapir- like species of the genus Diplacodon of Marsh, related to Palceosyops of the Bridger group and to the Titanotheres of the Miocene ; species of Amynodon of Marsh, related to the Rhinoceros ; the Epiliippus gracilis of Marsh, an early form of the Horse ; also the earliest of the Camel group, Leptotragulus of Scott and Osborn; and of the Oreodonts, Protoreodon; a single genus of Creodonts, besides many other kinds. The sea-border Jackson beds of Mississippi, Alabama, Georgia, and South Carolina have afforded bones of two whale-like Mammals of the genus Restoration of Palaeosyops paludosus (x 5 ^) by C. Earle, 1892. 908 HISTORICAL GEOLOGY. 1532. Zeuglodon, one of which, Z. cetoides, was nearly 70 feet long. One nearly perfect skeleton was found in place by S. B. Buckley in Clark County, Ala., about 100 miles north of Mobile, having the length here stated. Vertebrae were so abun- dant, on the first discovery, in some places that many of these Eocene whales must have been stranded together, in a common catastrophe, on the northern borders of the Mexican Gulf, possibly through a series of earthquake waves of great violence ; or, by an elevation along the sea limit that made a confined basin of the border region, which the hot sun rendered de- structive alike to Zeuglodons and their game ; or, by an unusual retreat of the tide, which left them dry and floundering for many hours under a tropical sun. The Zeuglodon is the Basilosau- rus of Harlan (1834), the Zeuglodon of Owen. Some of the dorsal vertebrae have a length of a foot and a half, and a diameter of a foot ; and a rib, a length of nearly six feet. Fig. 1532 represents one of the molar teeth, the yoke-like form of which suggested the name Zeuglodon, from evy\-q, yoke, and oSovs, tooth. Some of these teeth had a longer diameter of four and a half inches. MIOCENE. The Miocene Ungulates were of different species from those of the Eocene, and mostly of different genera. Tooth of Zeuglodon cetoides (x ). D. 1533. Titanotherium giganteum of Leidy (x Restoration by Scott and Osborn. In the earliest of the White River group, the Titanotherium ' beds, the species include the gigantic Titanotheres ; new Horses of the genus Mesohip- CENOZOIC TIME TERTIARY. 909 pus; several new genera of the Hog family, among them species of Elothe- rium as large as a Rhinoceros. The Titanotherium giganteum of Leidy (1852) is one of the earliest species discovered in the White River region. The restoration, Fig. 1533, -j^ the natural size, is by Scott and Osborn. The length was over 13 feet. 1534. Restoration of Brontops robustus (x^V). Marsh. Fig. 1534 represents a restoration, -^ natural size, of another of these Titanotheres, the Brontops robustus of Marsh. The length of body was nearly 12 feet. 1535. Elotherium crassum of Marsh (x 3^). A restoration of one of the Artiodactyl Ungulates is shown in Fig. 1535, representing a large species of Elotherium, E. crassum of Marsh. Its length was about seven feet. Its remains occur in Colorado and South Dakota. 910 HISTORICAL GEOLOGY. Above the Titanotherium beds lie the Oreodon beds, so named from a characteristic Artiodactyl, between the Hog and Deer in structure. Fig. 1536 represents, natural size, the skull of the species, Oreodon gracilis of Leidy. The Oreodon beds have afforded, besides species of several genera occurring in the Titanotherium beds, remains of Tapir-like Ungulates of the genus 1536. Oreodon gracilis. From Leidy. Protapirus ; also others related to the Khinoceros, teeth from one of which, of the genus Hyracodon (H. Nebrascensis of Leidy), are shown in Fig. 1537. There were also species related to the Camel; the earliest of true Carnivores ; the earliest known of Bats ; of Squirrels of the modern genus Sciurus, with many other Kodents ; and Marsupials of the modern genus Didelphys, or that to which the Opossum belongs. 1537. Teeth of Hyracodon Nebrascensis. Leidy. The following is a restoration, y 1 ^ the natural size, of Poebrotherium labiatum of Cope, by W. B. Scott, a species of the Camel family, near the Llama in its proportions. It is a fine example of a two-hoofed Artiodactyl. Its characteristics will be understood after a comparison of the feet with those of Phenacodus, Fig. 1517. The foot in Fig. 1538 includes the part CENOZOIC TIME TERTIARY. 911 of the leg from / to t. Moreover, the upper ends of the tibia and fibula are soldered into one bone. In many species of Artiodactyls the soldering is so complete that no suture is left to indicate it. This addition to the length of the legs, by putting the foot vertical on its toes and elongating the foot 1538. a f a ABTIODACTYL UNGTTLATB. Fig. Poebrotherium labiatum, restoration (x ^) ; a, b, same, feet, less reduced. Scott. (especially the metatarsal and metacarpal bones), was of great advantage to the running animal ; for it served, as also in the Horse, to give a propor- tional increase of speed, other things equal. The Fauna comprised also several Insectivores ; also Beavers, among Rodents, as the Palceocastor Nebrascensis Leidy, besides other species. The Protoceras beds of Wortman, making the upper part of the White River group, are characterized by various Artiodactyls related to the Camel, Deer, and Hog, and the remarkable Protoceras of Marsh, which has long canines and horn-cores, the fore feet 4-toed, while the hind feet are 2-toed ; also others related to the Tapir and Rhinoceros, and various Carnivores and other species. The John Day beds of Oregon are characterized by the genera Mioliippus, Diceratherium, Thinohyus, Poebrotherium, Eporeodon, Elotherium, various Eodents and Carnivores of the genera Cynodon, Temnocyon, Dinictis, and others. In the Deep River beds of the Upper Miocene occur the first known of Mastodons (M. proavus of Cope), Rhinoceroses of the genus Aplielops, several genera of the Horse type, Mioliippus, Desmatippus, Anchitherium, Proto- hippus. The Loup Fork beds are characterized by species of Procamelus, and the related Protolabis, Protohippus, Aphelops, Mastodon (M. mirificus of Leidy), and by Deer of the genera Blastomeryx and Cosoryx, together with Carni- vores of the genera Canis and Machoerodus. 912 HISTORICAL GEOLOGY. The Miocene of the Atlantic border has afforded remains of many Cetaceans. Among them are various Dolphins, several species of Whales of the genus Squalodon, related Oromeryx. Creodonts : Mesonyx, ? Miacis. Quadrumana : Hyopsodus. MIOCENE. 1. LOWER MIOCENE. A. WHITE RIVER GROUP. (In part, Oligocene of W. B. Scott.) (1) Titanotherium beds. Ungulates: Titanotherium, Brontotherium, Brontops ,* Teleodus, C^NOPUS, Mesohippus, Colodon ; SCHIZOTHERIUM (Canada) ; Artiodactyl Ungu- lates, f Oreodon, ELOTHERIUM, ANCODUS (HYOPOTAMUS), ANTHRACOTHERIUM, Poebrothe- rium, 9 Leptomeryx, ? Hypertragulus. Creodonts : Hemipsalodon (near Pterodon, Canada). (2) Oreodon beds. Marsupials: DIDELPHYS ! Rodents: Ischyromys, Gymnopty- chus, Heliscomys, STENEOFIBER, SCIURUS, EUMYS, Palceolagus. Ungulates: MESOHIP- PUS, C^ENOPUS, Hyracodon, Metamynodon, Colodon, PROTAPIRUS ; Artiodactyl Ungulates, Oreodon, Agriochcerus, ANCODUS ; ELOTHERIUM, ANTHRACOTHERIUM, PERCH have been found also in France, Switzerland, and other parts of Europe, and also in Sind, India. In the Miocene, Europe had its species of Ant-eater, the Macrothei'ium, which was an Un- gulate, related to the later Chalicotherium. The Pliocene of Europe has afforded also species of the Baleen Cetaceans (Whale-bone Whales). Species of the genus Cetotherium occur in the Pliocene of England and Belgium, and also, according to Lydekker, in the Miocene of Patagonia, along with Cetaceans of other Dinotherium gi gant eum (x A) . genera. All the Fishes, Reptiles, Birds, and Mammals of the Tertiary are extinct species. Subdivisions and Characteristic Species. Lower Eocene. (1) CERNAYSIAN (= PUERCO). Beds at Reims and La Fere in the adjoining departments of Marne and Aisne in northern France. At Cernay, near Reims, occur the following Mammals : MARSUPIAL : Neoplagiaulax. CREODONT : Arctocyon, Hyodectes, Heteroborus. INSECTIVORE : Adapisorex. QUADRUMANA : Plesiadapis, Proto- adapis. There are also the BIRDS, Gastornis Edwardsi, Eupterornis. In overlying beds occur Hycenodictis, Proviverra, Plesiadapis, with Teredina personata ; and some sand-beds afford Cyrena cuneiformis, Melania inguinata, Cerithium variabile. (2) SUESSONIAN of d'Orbigny (= Wasatch, the Landenian of Belgium). Includes the Thanet sands of the London basin (Thanetian, of Lapparent). Also, (a) the marls of Meudon, with (6) Lignitic clays, and (c) Plastic clay, but more marine in Belgium, to which correspond the stages (a) Maudunian, (6) Sparnacian, and (c) Tpresian. The Paniselian beds of Dumont are part of the Ypresian. IN ENGLAND. Thanet sands. Pholadomya cuneata Sow., Cyprina Morrisii Sow., Corbula longirostris Desh., Scalaria Bowerbankii Morr. Woolwich and Reading beds. Cyrena cuneiformis Fer., C. tellinella Fer., Melania inguinata Dfr., Ostrea bellovacina Lam. London Clay (Island of Sheppey, etc). Nautilus centralis Sow., N. imperialis Sow., Aturia ziczac Bronn, Belosepia sepioidea Blv., Valuta Wetherellii Sow., V. nodosa Sow., Aporrhais Sowerbyi Mant., Cyrena cuneiformis, Cryptodon (Axinus} angulatus Sow., Leda amygdaloides Sow., Pinna affinis Sow. VERTEBRATES of the London clay. FISHES AND REPTILES : Tetrapterus priscus Ag., Pristis bisulcatus Ag., Lamna elegans Ag., Palceophis toliapicus Owen. MAMMALS. MARSUPIAL : Didelphis. UNGULATES : LopModon, Miolophus, Hyracotherium, Coryphodon. In France, at Meudon, Coryphodon, Palceonictis, Phenacodus, with Gastornis. Middle and Upper Eocene. PARISIAN (= the Bridger beds). (1) The Calcaire grossier of Paris (Lutetian of Lapparent) ; with above, (2) the sands of Beauchamp, France, etc. ; Bagshot sands of the London Basin, and the Barton clay of the Hampshire Basin, England (Bartonian). 926 HISTORICAL GEOLOGY. IN THE BAGSHOT SANDS, ENGLAND. Nummulites levigatus Lam., Cardita planicosta Lam.,' Pleurotoma attenuata Sow., Turritella multisulcata Lam., Conus deperditus Brngt., Lucina serrata Sow. ; Myliobatis Edwardsi Dixon, Carcharodon angustidens Ag., Otodus obliquus Ag., Galeocerdo latidens Ag., Lamna elegans Ag. Reptiles, Palceophis typhceus Owen, Gavialis Dixoni Owen, Crocodilus Hastingsice Owen ; Mammals, Dichodon cuspi- datus Owen, Lophiodon minimus Cuv., Microchcerus erinaceus Wood, Paloplotherium annectens Owen. Barton Series. Mitra scabra Sow., Valuta ambigua Lam., Typhis pungens Morr., Valuta athleta Sow., Terebellum fusiforme Lam., T. sopita Morr., Cardita sulcata Morr., Crassatella sulcata Sow., Nummulites variolarius Morr. (variety of N. radiatus Sow.), Chama squamosa Brand. The CALCAIRE GROSSIER contains many species of Fishes, and also of other tribes identical with those of the Upper Eocene of England. Oligocene. LUDIAN (= Uinta beds). The Montmartre gypsiferous marls of Paris, Bembridge and Headon beds of the Isle of Wight. TONGRIAN ( = White River beds; Upper Oligocene, of Europe). Includes the Hempstead beds of the Isle of Wight, the Fontainebleau sandstone, in France, clays with Gyrena convexa, near Tongern in Belgium, the Lower marine Molasse of Switzerland. The name Rupelian is given in Belgium to an upper portion of the beds ; and Bolderian to still higher beds. Headon Series. Planorbis euomphalus Sow., Helix labyrinthica Say, Neritina con- cava Sow., Limncea caudata Edw., Cerithium concavum Desh. ; Lepidosteus ; Reptiles, Emys, Trionyx ; Mammals, Palceotherium minus Cuv., Anoplotherium, Anthracotherium, Dichodon, Dichobune, Spalacodon, Hycenodon. Bembridge Series (120 feet thick). Cyrena semistriata Desh., Paludina lenta Desh., P. orbicularis Voltz., Melania turritissima Forbes, Cerithium mutabile Lam., Cyrena pulchra Morr., Bulimus ellipticus Sow., Helix occlusa Edw., Planorbis discus Edw. ; MAMMALS: Palceotherium magnum Cuv., P. medium Cuv., P. minus Cuv., P. minimum Cuv., P. curium Cuv., P. crassum Cuv., Anoplotherium commune Cuv., A. secundarium Cuv., Dichobune cervinum Owen, Chceropotamus Cuvieri Owen. From the Montmartre gypsum beds of France, and equivalent beds, have been obtained species of the genera Palceotherium, Anoplotherium, Xiphodon (X. gracilis} ; the Carni- vores, Hycenodon (H. leptorhynchus Blv.), Cynodon Parisiensis Pomel, Bats, and Opossum. The Phosphorite beds of Quercy, referred to the Oligocene, have afforded Palceothe- rium, Anoplotherium, Xiphodon, Hycenodon, Cynodictis, Cebochcerus, along with Amphi- tragulus, Aceratherium, Necrolemur, and others. Lapparent divides the Oligocene into the Tongrian and Aquitanian stages ; and the Tongrian into Sannoisian and Stampian substages. The Hempstead beds of England have afforde'd Corbula pisum, Cyrena semistriata Desh., Cerithium plicatum, C. elegans, Eissoa Chastelii, Paludina lenta, Melania fasciata, M. costata Sow. ; the Mammal, Hyopotamus bovinus Owen. Lower Miocene (= John Day Beds, Lower Miocene, in Germany, etc.). Lacus- trine limestone of Beauce and Meulieres de Montmorency, in France, and limestone of Agenais in Aquitania, southwest France ; Red Molasse, Lignitic Molasse in Switzerland. 1. MAYENCIAN (Langhian, Burdigalian). Freshwater Molasse of Switzerland ; beds at Mayence, Belgium. 2. HELVETIAN. Marine Molasse of Switzerland, Faluns of Anjou with Ostrea cras- sissima, etc., of Touraine, in western France, Molasse of the Superga, Italy. Upper Miocene. TORTONIAN. Marls with Helix Turonensis in western France; (Eningen beds, Leitha limestone near Vienna, Blue marls of Tortone in Italy. Above CENOZOIC TIME TERTIARY. 927 the Tortonian, the stages Sarmatian and Pontiem are recognized in Dauphine, Austria, and Italy. Some of the Miocene genera are Pliopithecus, Dryopithecus, of Quadrumanes ; Machcerodus, Felis, Hyceuarctos, Hycena, Canis, Viverra, Mustela, of Carnivores ; Mas- todon (M. longirostris, M. tapiroides Cuv., etc.), Elephas, Dinotherium; Rhinoceros, Listriodon, Sus, Anchitherium, Hipparion, Equus, Hippopotamus; Camelopardalis, Ante- lope, Cervus, of Ruminants ; Erinaceus, Talpa, of Insectivores ; Halitherium, Squalodon, Physeter, Delphinus. The Tertiary Mammals of the Siwalik Hills, India, from beds now referred to the Pliocene, include, besides Quadrumana, species of Hycenarctos, Hycena, Machcerodus, Felis, Canis, Mustela, Viverra; Elephas, Mastodon, Rhinoceros, Hexaprotodon, Hippo- therium, Equus, Hippopotamus, Sus, Anoplotherium, Chalicotherium, Merycopotamus, Camelus, Camelopardalis; Sivatherium, Antilope, Moschus, Cervus, Ovis, Bos; Dinothe- rium; Hystrix; Enhydriodon. The Sivatherium was an elephantine Stag, having four horns, allied to the Deer, but larger, being in some points between the Stags and Pachy- derms. It is supposed to have had the bulk of an Elephant, and greater height. Bos and the related genera probably occur nowhere earlier than the Pliocene. There were also Crocodiles of large size, and the great turtle Colossochelys Atlas. In southern South America, the Santa Cruz beds, which are referred to the Miocene, afford species of Edentates, Rodents, Marsupials, Nesodon, Toxodon, Prototherium, Prosqualodon, Argyrocetus, Odontoceti, or Toothed Whales, and other species. The following new Miocene species from East Siberia have been described and figured by W. H. Ball : Semele Stimpsoni, Siphonaria Penjince, Conus Okhotensis, Cerithium cymatophorum, Diloma ruderata ; and he has identified also Ostrea gigas Thunberg. They occur in a bed in the northeastern angle of the Okhotsk Sea, on a small bay in the Gulf of Penjinsk containing a layer of coal. They were brought from the region in 1855 by Wm. Stimpson, a member of the Ringgold and Rogers Exploring Expedition. The fauna is related to that of the China and South Japan seas, and indicates, states Ball, a change downward of water temperature since the Miocene of 30 to 40 F. Lower Pliocene. MESSINIAN, the Zanclean beds in Italy of Seguenza, and over the Zancleau beds, along the Apennines, Plaisancian of Seguenza. Upper Pliocene. ASTIAN. Crag of Norwich, etc., Eastern England; Subapennine marls and sands of beds of Val d'Arno. In the Red Crag, Felis pardoides Owen, Mastodon Arvernensis Croizet & Jobert (angustidens Owen), Rhinoceros Schleiermacheri Kaup (incisivus Cuv.), Tapirus priscus Kaup (Arvernensis Croizet & Jobert), Cervus anoceros Kaup. In the Norwich Crag, Mastodon Arvernensis, M. longirostris, M. Borsoni, Elephas meridionalis, Cervus Falconeri, C. verticornis. Forest bed of Cromer on the east coast of England, referred by many to the Lowest Quaternary, includes, besides the Cave Bear, the Irish Deer ; and several modern species, as the Beaver, Wolf, Fox, Stag, Aurochs, Mole, Wild Boar, Horse ; also the European Pliocene species, Ursus Arvernensis, Cervus Polignacus Robert, Hippopotamus major Cuv., Rhinoceros Etruscus, R. megarhinus, Elephas meridionalis, E. antiquus, Equus Stenonis, and without any remains of man. The Forest bed is made Pliocene in the Manuals of Etheridge and H. B. Woodward, but lower Glacial by Geikie and others. The Pikermi Middle Pliocene beds in Greece contain out of 29 genera of Mammals, 18 that are found also in the Middle Pliocene of the Siwaliks'of India; there is the same remarkable abundance of true Ruminants, and among them, as in the Siwaliks, several species of Giraffidce and Antelope; there are at Pikermi 15 Ruminants to 1 Pig and 1 Chalicotherium, and in the Siwaliks 37 Ruminants to 12 other Artiodactyl Ungulates (Oldham, Geol of India). 928 HISTORICAL GEOLOGY. GENERAL OBSERVATIONS ON THE TERTIARY. BIOLOGICAL CHANGES AND PROGRESS. The precursors of the Tertiary Mammals. No immediate precursors of the Tertiary non-marsupial or placental Mammals, linking them to the Marsupial, have yet been found in any part of the world, notwithstanding the occurrence in many regions over America as well as the other conti- nents of a gradual passage from the Cretaceous formation into the Tertiary. They are naturally supposed to have existed in the later Cretaceous over the dry land of eastern and western America ; but still it is strange that they did not find resorts somewhere on the border of the Cretaceous seas along with the Marsupials. The nearest approach in the Reptilian type to the Mammalian yet known was made by the stupidest of the Dinosaurs^ which had a pair of Bovine horns and two-pronged teeth. Early prototypic character. Another strange fact is that although the Marsupials of earlier time had become variously specialized, their placental successors should have had unspecialized or prototype characteristics, such as, have been described ; that there should have been at this time so striking a starting from what appears to be a new beginning. The removal of the former mystery may also remove this. Moreover, it is to be considered that among the fossils of the Mesozoic Marsupials, remains of the limbs, or of any parts of the skeleton excepting the jaws and teeth, are of very rare occurrence. DIVERSITY OF EOCENE MAMMALS. Another remarkable fact is that so great a diversity of Mammals, diversity in structure as well as size, should have appeared before the Eocene period had passed. The prototypic plant- eaters and flesh-eaters of the earliest part, supposed to be plantigrade in feet, were followed, even in the Wasatch division of the Lower Eocene, by species. of large, short-footed Ungulates, the Coryphodonts, and in the later Eocene huge Dinocerata, the latter supplied with horns for attack and defense. In the Eocene, also, the Tapir-like species advanced far toward, the modern genera, Tapirus and Rhinoceros. There also appeared various species with paired toes, in the line of the Hogs, Hippopotamus, Camel, so that the type of Artiodactyls, and the types of several of its principal subdivisions, were established. There were also some prominent Eocene types of Rodents and Insectivores. Further, the Quadrumana of the Early Eocene, having the typical number of teeth, 44, were followed in the Later Eocene, by others, in which the number of teeth was reduced to 32, the final limit in the Quadrumana, and that characterizing Man. Moreover, there were several successions of Mammalian faunas in this first period of the North American Tertiary, and the species in each of them probably outnumbered those of Recent North America. The kinds found fossil may have been a fourth of all then existing in the region, and probably not more. Loss of prototype characters. Very early in the Eocene, prototype charac- CENOZOIC TIME TERTIARY. 929 ters began to disappear. The teeth had the typical number, 44, reduced ; their structure made more complex ; and their characters varied otherwise through use and adaptations to different purposes. The feet had the number of digits reduced in most Ungulates, but not in the Coryphodon line, or in the Carnivores, or the Quadrumana, or rarely in the Insectivores or Rodents. Moreover, the feet lost the plantigrade tread in the Herbivores, and Carnivores, but not in the Quadrumana, Insectivores, or Rodents. In most of the larger species the regularity in the carpal and tarsal series of the feet gave way to the oblique or alternating position of the bones required for firmness in running. Some of the causes favoring change. The development of so great a diversity of Eocene Vertebrate structures is the more remarkable in view of the absence of all evidence as to any great physical or meteorological dis- turbance to require new adaptations. No change of climate is indicated beyond what might have occasioned a feeble amount of migration. No evi- dence of disquiet in the earth's crust has been noted, excepting that relating to the imperceptible geosynclinal movements over the areas of the Eocene lakes attending the slow deposition of sediments. The only sources of disquiet that can be appealed to as causes of bio- logical change, are biological sources proceeding from the appetites or needs or impulses of the animals. Of these appetites the dominant one, the most imperative, the only daily recurring one, was the demand for food. As nearly half of the Mammals lived on animal food, there was perpetual strife between the stronger flesh-eaters and the weaker, and between all flesh-eaters and other species. It would naturally have driven the weak kinds to holes, or somewhere out of reach of their enemies, where poor food, darkness, and other privations, would have been unfavorable to high progress. The strife, moreover, as writers on the derivation of species have illustrated, would have promoted fleetness, cunning, devices for protection, and have favored those changes in the Mammalian structures that would better fit or accom- modate the species to the new demands. The evolution of the Horse through the necessity of running to escape from enemies has often been set forth as an example of the effects, under certain conditions, of such a cause. An animal of primitive Ungulate type, having the third or middle toe the longest of the five, raising itself on its toes for greater speed in running, and forcing itself forward naturally by its longer toe, had this toe, as Eocene and Miocene time passed, with the bone of the foot above it (the metatarsal and the metacarpal) enlarged and elongated, while the less-used toes either side dwindled till too short to reach the ground ; and finally, through these and other concurrent changes, there was evolved, a long-legged one-toed animal the Horse. It became tall and long-legged, not only by elongating growth in certain bones, but also through the functional appropriation by the leg of all of the foot excepting the terminal hoofed joint. DANA'S MANUAL 59 $30 HISTORICAL GEOLOGY. For the Artiodactyl, the theoretical history is the same, excepting that -i- two toes, the third and fourth, were concerned instead of one the two acting together in dynamical unison. An early Ungulate rising on these two toes in running in order to make thus its greatest speed, the toes and also their metatarsals and metacarpals became equallv enlarged and alike elon- gated, while the less-used toes either side, the second and fifth, became a shorter, weaker pair as illustrated in the Hog ; or, after further change, the dominant pair became still longer, while the shorter was reduced to a rudimentary pair or to hoofs, or became wholly obsolete excepting meta- carpal and metatarsal splint bones, as in the fleeter Artiodactyls. Further: the stroke of the foot demanded, for high speed and safety, that there should be little or no rotation of the foot by a movement of the bones of the lower leg, that is, of the radius and ulna of the front pair and the tibia and fibula of the hind pair, and consequently the ulna and fibula became reduced sometimes to splint bones, or united by coossification sever- ally to the radius and tibia ; and likewise, in the two-toed Artiodactyl, the corresponding two metatarsals and metacarpals, having no movement between them, became coossified into a " cannon bone." There is little that is hypothetical in the above statements, for the suc- cessional lines and the sutures of half -finished coossification are fully illus- trated among the species. Modern surgery finds that bones at joints become coossified by too long confinement in splints without a chance for movement. The variety of four-toed Artiodactyls during the Tertiary was very large ; but at present they are confined to the few of the Suillines, or the Hog family, and the Hippopotamus group. The two-toed species, on the contrary, or the Stags, Deer, Cattle, and the like, are most abundant in recent time. The following considerations bear on the character of the changes that went forward among the Mammals. Of the three divisions (1) the Plant- eaters, (2) the Animal-eaters, (3) the Omnivores, the last-mentioned, that is, the Quadrumana or Monkeys, must have early taken to the trees, as their habits indicate. This was an easy method of escaping enemies. Being strong in their fore limbs, they had the trees and the ground, fruit and flesh, within their range. For defense or attack they needed no abnormal growths, such as horns ; and they have been from the first without them. The Animal-eaters, in their development, would have divided according to food and habits. Those forced to take the poorest and most abundant and easily got of animal food, the Insectivores, fos serial and skulking species, degenerated, becoming small species, mostly remaining plantigrades, the teeth in some losing their differentiation, in others disappearing altogether. The insects which they ate needed no chewing. Some of them found pro- tection in the substitution of spines for fur (the Hedgehogs), and in the safe but cowardly method of rolling into a ball with spines out in all directions. The higher section of the Animal-eaters, or the Carnivores, living on the best of animal food, and generally having to fight for it, and always on the alert, having the fore limbs the stronger pair, and efncient as arms in secur- CENOZOIC TIME TERTIARY. 931 Ing or holding food, and jaws armed with long canines, they, too, needed no abnormal growths for defense or attack. The larger Plant-eaters, who dared to face the Carnivores, at least when escape was not easy, whose legs, while good for locomotion, were of no ser- vice for prehension or attack, *ised themselves as battering-rams, with the head as the striking et>d and the means also of tossing away or rending the daring enemy. Under the necessities of their condition, the forehead and nose grew horns, and a pair of teeth became elongated into tusks. As the legs, besides, were of no service for gathering food, the nose, as well as the elongated canines, was sometimes made to serve for grubbing ; and the nose thus used became elongated, until the Tapir's nose could pull over a tree, and the Elephant's serve as a long agile arm of great strength and wide diversity of work. Such abnormal growths are characteristics of Herbivores alone. The graceful Horse is one of the exceptions among Herbivorous locomotors, for it finds its chief means of attack in its hind legs, and of escape in its fleetness. Great degeneration also took place among the Mammals ; for before the close of the Eocene there were Whales in the seas the Zeuglodons. The species is supposed, from its teeth and food, to be a degenerate flesh-eating species, which, for escape, took to the water, where support from limbs is not needed. In this supporting element the body became enormously enlarged and multiplicate in its vertebral column, like the Sea-Saurians, the length being increased from four or five feet to 70 feet, and the size of the dorsal vertebrae to a diameter- of a foot and a length of a foot and a half. Its teeth remained few, 36 ; and the molars retained their two roots, but the distinction between molars and premolars was lost. Further: in the Miocene, as stated on page 912, Whales appeared of greater degeneration along two or more lines : species appearing that were multiplicate in teeth, and in the phalanges of some of the digits of the fore limbs, as well as in vertebrse ; others that had teeth only in one jaw and all single-rooted ; and still others that had no teeth, but only plates of whale- bone with unravelled edges in a huge mouth to strain out small animals from the sea-water for food. It may be supposed that these aquatic animals became urosthenic, like Fishes, because sculling with the whole posterior part of the body was their best mode of progression ; that the body became long and almost indefinite in number of vertebrse, to secure greater force in the sculling organ ; that the hind limbs disappeared because useless ; and that, in one branch of the tribe, the teeth began to disappear altogether when the smaller swarming life of some parts of the ocean received into the mouth almost without effort, began to satisfy appetite. It may also be presumed that the whale-bone plates, over 350 in number, either side of the middle line, grew downward from the palate just as soon as they were needed ; but the question, what made them grow, remains, as in many like cases, unanswered. In the young state these Whales have rudimentary teeth. The results were much like 932 HISTORICAL GEOLOGY. those that had before occurred in Reptiles. It was progress downward almost indefinitely, but without loss of the essential characteristics of a Mammal. The above examples and explanations may serve to illustrate some of the methods by which the modifications of species are supposed to have taken place without the aid of physical catastrophe. The great diversity in the characters of Eocene Mammals, wrought out, it is believed, in such quiet times, teach this plainly that the first period of the Tertiary was exceedingly long, whatever may be gathered to the contrary from some persistent Cretaceous plants. OROGENIC AND EPEIROGENIC MOVEMENTS. In the opening of the Tertiary era geological history reaches the time when, as mentioned under Dynamical Geology, besides the making of great mountain ranges, nearly all the mountain chains of the world received additions of many thousands of feet to their heights and hundreds of thou- sands of square miles to their areas ; and also when igneous eruptions took place of extraordinary extent. 1. Orogenic movements at the dose of the Nummulitic epoch of the Eocene. In Europe, the elevation of the Pyrenees, and of some other heights in eastern Europe, occurred after the marine Nummulitic beds of the Eocene had been deposited. The mean direction of the Pyrenees is about N. 80 W. There are large flexures and steep slopes on the side toward France, but less upturning and gentler slopes toward Spain. 2. Orogenic movements at the close of the Miocene. In North America an upturning took place at this epoch along the coast region of California, and Oregon, tilting and, in some cases, flexing the Miocene, Eocene, and Cretaceous formations, 5000 feet or more in thickness, as is proved by Mio- cene fossils in the upturned beds (J. D. Whitney). The earlier Jurassic strata are believed to have been earlier upturned and metamorphosed, being, of cotemporaneous origin with the Sierra Nevada. At this epoch also the great upturning of the Alps and Juras occurred briefly described on page 367. It gave to the mountains the bold flexures of the Mesozoic formations with the overlying Eocene and Miocene, which are a remarkable feature of many of the lofty summits. The Apennines,, according to Stefani, passed through a crisis of upturning and flexures at the close of the Nummulitic Eocene, like the Pyrenees, and also at the close- of the Miocene, with the Alps. The Himalayas were, to a large extent, beneath the sea during the Nummulitic epoch, and at least 20,000 feet lower than now (page 368). Either directly after this epoch, or before the close of the Miocene, there was an upturning and flexing of the Nummulitic and underlying Cretaceous beds (down to the top of the Carboniferous) and the commencement of the final elevation of the mountain chain. According to the Geological Survey CBNOZOIC TIME TERTIARY. 933 of India, the beds above the Nummulitic formation at the top of the upturned series are probably Miocene, as indicated by the plant beds, one species, the Sabal major, ranging from Lower to Middle Miocene in Europe. The Siwalik Tertiary beds (of the Sub-Himalayas), many thousand feet thick, along the length of the Himalayas, which are Pliocene with probably Upper Miocene at top, rest on the inferior Mesozoic and Paleozoic rocks along what appears to be an enormous fault-plane. This steep "fault- plane," as shown by Medlicott, is really an original limit of deposition, in part almost cliff-like, to the north of which the Siwalik beds never extended. These beds are, therefore, not included in the disturbed region. There appears to be doubt remaining whether the epoch of upturning followed the close of the Nuinmulitic Eocene or that of the Miocene. The mountain chains to the north of the Himalayas for 22 of latitude are nearly parallel to it, and this has led to the suggestion that all this great region in Asia was involved in one system of orogenic movements. Epeirogenic movements during the Tertiary era. Through the Tertiary, changes of level went slowly forward by geanticlinal bendings of the earth's crust and slippings along old or new fracture planes, giving great altitude to vast continental areas, and especially those within 800 miles of the sea- border, and affecting all the continents alike with the same stupendous results. The continuing of the movements through all Tertiary time, and also beyond it, during part of the Quaternary, teaches that they were extremely slow in general progress ; yet sudden slips of scores and hundreds of feet were probably among the events. In the Kocky Mountain region the change was slight during the Eocene, arid yet it was sufficient to modify the outlines and positions of the Eocene lakes. With the close of this period, the land was so far raised that the Eocene lakes were drained; but the elevation attained was so small, as Hayden first remarked, that vast Miocene lakes covered a large part of what now constitutes the eastern slopes of the mountains, and continued into the Pliocene. The long continuance of the lakes indicates not only slowness of emergence, but also that the movements were interrupted through long intervals. The western margin of the Nebraska lacustrine beds is 3500 feet above the level of the eastern, the former having a height of about 6000 feet and the latter of 2000 feet. This is proof that the elevation of the moun- tains went on through the Pliocene, for the rise to the westward could not have made much progress in the Miocene without drying up the lake. The height which the Eocky Mountains had reached by this change of level is not ascertained. This much is known: (1) that the Cretaceous areas were originally at or near the sea level ; and (2) that within the area of the United States the present height of the upper beds is now, in part, 13,000 feet. Moreover, the corresponding height in central Mexico is 10,000 feet, and in British America, toward the Arctic seas, 4000 feet. During the progress of these changes over western North America there were also, according to Gilbert, Powell, L^Conte, and others, faults along 934 HISTORICAL GEOLOGY. fracture-planes thousands of feet in displacement in the mountain ranges of the Great Basin, the High Plateaus of Utah, the Wasatch Mountains, and the Sierra Nevada. Through a study of the river systems of the Sierra Nevada, it has been proved by LeConte (1886) that a great elevation of the Sierra took place at or near the close of the Pliocene. The drainage of the Sierra is chiefly to the westward, the eastern front being very steep. Whitney describes in his Keport (1865) the facts respecting an early system of valleys having been covered up and obliterated by basaltic eruptions, and the new and much deeper system of subsequent time (page 300). He illustrates also, by a plate in his work on the Auriferous Gravels (1880), the difference in the depth of erosion of the two systems, the earlier that occupied all Cretaceous and Tertiary time, and the later, of subsequent time after the eruptions. In view of these and related facts, LeConte urges that the deeper erosion by the existing streams, although their time of work was short compared with that of the earlier system which existed through the Cretaceous and Tertiary, proves that a great elevation of the Sierra Nevada, increasing the fluvial denuding power, took place soon after the Pliocene ; and that this was accomplished by a rise along a fault-plane having the course of the steep eastern front of the range. It is to be remarked that the Glacial period followed the Pliocene; and its glaciers and abundant precipitation would account for part of the profound denudation of the later rivers. But this fact does not invalidate seriously the conclusions. It is sustained through additional facts by other geologists, including Lindgren and Diller. The eastern border of the continent underwent only small changes. At the close of the Eocene some modification of the surface occurred within the Mexican Gulf which put an end to the deposition of true marine beds along its northern beds west of Florida. The only Miocene beds recognized are of fresh-water or brackish-water origin. With the close of the Tertiary, and probably before the Pliocene had fully passed, elevatory movements occurred which raised the Tertiary of the Atlantic border about 100 feet, and that of the Gulf border not much more, except along a region in Georgia, and the border of Alabama in a line with the Peninsula of Florida, where the height is 300 to 400 feet above sea level. A Florida axis of elevation is indicated by it. On Long Island, Martha's Vineyard, and other islands south of New England, occur upturned beds of the Cretaceous or Cretaceous and Tertiary, indicating orogenic movements before the Quaternary. See further, page 1021. The elevation of the Atlantic border may have been part of a greater change which affected also the whole of the Appalachian region; but no posi- tive evidence of this is yet obtained. What was the total gain in mass through the great Tertiary elevation of the North American continent ? On this point little is known with regarcl to its eastern half, but the western affords available facts. With the opening of the Tertiary the larger part of the western half of the United States was at the water's level from the eastern foot of the Sierra Nevada CENOZOIC TIME TERTIARY. 935 near the meridian of 120 to the meridian of 97, or through a breadth of 23, or nearly 1500 miles. The higher emerged peaks of the Bocky Mountain region were perhaps 4000 or 5000 feet out of water ; the Sierra Nevada, 3000 to 4000 feet. Many peaks have Cretaceous rocks at a high level ; one, Slaty Peak, in Colorado, at 13,000 feet, and this is supposed to have lost 3000 feet of Upper Cretaceous by denudation. The floor of the Great Basin was probably at a height of 1000 feet and less, and its ridges 2000 to 4000 above sea level. Almost all the rest of the surface was near the sea level or below it. The geanticline added at least 13,000 to the height of the summit region ; of cen- tral Nebraska, 3000 feet (taking only present altitudes), and of western, 5000 to 6000 feet; of Colorado, east of the Front Eange, 6000 to 7000 feet; of central Mexico, at least 10,000 feet ; of the Sierra Nevada, 10,000, a third of it probably through the general geosynclinal movement, and the rest through one or more faults ; and so on. The average elevation of western North America was certainly tripled. This would make the increase of mass at least 10 times. But, as a large part was a total gain, since it rose from the sea level, the amount probably much exceeded this ; 12 or 15 times may be nearer the fact. Supposing no addition in the eastern half except that of the Cretaceous and Tertiary sea border, the gain in mass for the whole con- tinent would be over six times. It is to be admitted that the present elevation cannot in any region be a correct measure of the actual height at the close of the Tertiary. It is safe to say only that it is the final elevation after denudation and such Quater- nary oscillations as may have since occurred. The mean height may be much less now than it was at the close of the Tertiary. In South America, the region of the Andes through the length of the con- tinent underwent at the same time an elevation of many thousands of feet. In Ecuador, the Upper Cretaceous forms most of the peaks of the eastern Andes, and has a height in some of the ridges of 6000 meters (19,686 feet) ; in Peru, northeast of Lima in 111 S., near the Pass of Antaranga, a height of 4803 meters (15,754 feet) ; in the Province of Huarnachuco, 2000 to 5000 meters ; in 12 S., between Pachachaca and Jauja, the Gault, at 5000 meters (16,405 feet). In Haiti, according to Gabb, the Miocene has an elevation of 200 to 2000 feet ; and a sea-border of limestone, a height of 170 feet and less. In Jamaica there are 2000 feet or more of white limestone, and the rock covers six sevenths of the area of the island. A yellow limestone below on Jamaica is Miocene ; and the thick white limestones of Jamaica and Santo Domingo as well as of Cuba are probably of Tertiary origin, if not partly of Quaternary. On the Barbados, there is an oceanic deposit consisting of a score or two of feet of calcareous earthy material, largely made of Globigerinse, overlaid in some places by 100 to 130 feet of siliceous Radiolarian earth, and above this other calcareous and pumiceous beds, with red clays 100 feet or 'more ; and these beds underlie the elevated coral-reef rock of the island from the seashore to a height of 800 to 900 feet. They are regarded by Jukes-Browne and Harrison (1891, 1892) as probably Pliocene, and as evidence of a Pliocene subsidence of 2000 to 3000 fathoms, or to such depths as now afford similar 936 HISTORICAL GEOLOGY. Kadiolarian earths. The Barbados are outside of the outermost range of islands ; and whatever changes of level they have experienced may not have affected the Caribbean Sea. At present the bottom of this sea is made of Globigerina and not of Eadiolarian earth. Kadiolarian deposits occur also on Haiti, Jamaica, and Cuba ; but they have less extent and are less decisive as to change of level. Whether the following changes of level were epeirogenic or not is undecided. Over Europe and Asia the same elevation of the land over extensive areas was in progress, especially during the Pliocene. Europe was much changed in elevation cotemporaneously with the disturbance in the Alps ; and " by the close of the Pliocene all its main features had come into existence." The Alps were carried up probably 12,000 feet or more, and the Pyrenees over 10,000 feet. The Himalayan chain, a region of upturning at the close of the Miocene (if not before, at the close of the marine, Nummulitie epoch), when 20,000 feet lower than now, began afterward, or simultaneously, its slow emergence and attained its present level according to Blanf ord by the end of the Pliocene or in the early Quaternary. The Tertiary beds of the Sub-Himalayas, or the Siwalik Hills, which are chiefly freshwater Pliocene and contain the remains of the Fauna Antiqua Sivalensis, were laid down during the progress of the uplift. During all this Himalayan elevation, peninsular India underwent little change. Blanford derives additional evidence as to the remoteness of the time of the uplift, from the existing Mammalian fauna of Tibet. Out of 43 species of Mammals in Tibet, pertaining to 26 genera, 27 species and 4 genera are not known out of Tibet. Out of 16 species of Rodents, only one is not purely Tibetan. The various facts accord with the view that the elevation of the Himalaya E-ange commenced early in the Tertiary. During the early Eocene, as well as the Cretaceous period, the British Channel was crossed by an Interior basin, perhaps having, as Jukes-Browne suggests (1892), a range of land over the western part, uniting Brittany to Cornwall. But in the Miocene, on the same authority, even the area of the Eocene Anglo-Parisian basin had become dry land ; and in the Pliocene, ridges were formed crossing the Channel from northwest to southeast, as the Weald Axis, the Portsdown, the Purbeck corresponding to the axis of Artois, Bresle, and Bray to the south. Only in the Middle Quaternary, after a phase in which a passage extended across from below Dover and Brighton on the north to the Province of Calais in France, did the Channel secure its place through a general subsidence. " Thus, throughout the Tertiary era, the continents of Europe and Asia, as well as America, were making progress in their bolder surface features, as well as in the extent of dry land. The evidence is sufficient to show that, wnen the period ended, the continents had in general their mountains raised to their full height." The evidence is stronger now than it was, more than 30 years since, wher those words were written. Geosynclinal movements over the oceanic basin the " Coral Island sub- sidence" That there were profound geosynclhies over the oceanic basins during the later Tertiary and early Quaternary is put beyond question by CENOZOIC TIME TERTIARY. 937 the fact of the great continental elevations of the same time. The Coral Island subsidence, announced by Darwin in 1839, recognized such geosynclines ; and they were long since set forth by Dana as the counterpart of the conti- nental movements. The subsidence is thus a real event in geological history ; and if marvelous, equally so is that of the world's so recent elevations. " Gondwana-Land," connecting India with southern Africa (page 737), continued to exist, according to Oldham (1894), from the Carboniferous period throughout Mesozoic time, and " sank beneath the sea in the Tertiary era," leaving some volcanic and coral islands in its course, including to the northward the sunken atoll of the Chagos bank. The extension of " Gond- wana-Land" over the Indian Ocean is not here in view, because it is not loelieved to have ever been a fact. A paper by Haddon, Sollas, and Cole (E. Irish Acad., 1894), after men- tioning the observation of Jukes that the eastern mountain range of Aus- tralia, extending for 35 of latitude from Tasmania to the northern cape, Cape York, is continued in islands across Torres Strait to New Guinea, and describing the straits and the lands beyond, concludes that this southern continent lost its border lands of New Zealand, New Caledonia, and New Guinea and the intermediate islands "possibly during the great Alpine and Himalayan revolutions " of the Tertiary period. Igneous eruptions during the Tertiary. An eruptive period in the earth's history commenced in the Later Cretaceous (page 875) and passed its maximum in the course of the Miocene. Eruptions through fissures cov- ered vast areas of the Pacific slope with igneous rocks, and volcanic erup- tions made great volcanic cones, which added largely to the outflows and ejections. The eruptions continued through the Pliocene, and some of the cones are not yet extinct. The loftiest of the volcanoes are situated along the Coast region, from Washington to northern California, the heights vary- ing from 10,400 to 14,500; and those farther south along a belt through Mexico the highest three, Orizaba 18,200 fee$, Popocatapetl 17,500 feet, and Ixtaccituatl 16,770 are probably of like Miocene origin. Some of the regions of fissure eruptions have been already described. South of Lassen's Peak, in northern California, the southernmost of the cones of the Pacific border, the region of the Sierra Nevada had its outflows of broad streams of basalt from fissures which were later but up into Table Mountains ; and similar floods occurred over Nevada, New Mexico, and Arizona. The higher western slopes and summit region of the Rocky Mountains also had their cones. The Yellowstone National Park and its vicinity was one of the volcanic centers. Electric Peak and Sepulchre Mountain are two denuded cones in the Park, as described by Iddings ; Emigrant Peak, on the Yellowstone, 16 miles north of the boundary, is another, where dacyte and quartzose porphyry are the igneous rocks ; Haystack Mountain, 12 miles north of the east corner of the Park, is another, its cone consisting of gabbro and dioryte ; and another stands just east of the east corner of the Park, 938 HISTORICAL GEOLOGY. which is like the last in its rocks. Iddings refers these cones to the early Tertiary. He states that after a long period of eruption of acidic andesytes^ basic andesytes and basalts were ejected ; and after these had been much denuded, the great outflow of rhyolyte took place, forming the Park plateau ; and that finally the basalt was poured forth that extends widely over the Snake River plains in Idaho. Igneous eruptions occurred through all the successive geological ages. But at no time in American history since the Archaean, have they approached in extent those of the Later Cretaceous and Tertiary periods. It was a time of pouring from fissures and of the birth of volcanoes, as never before. It is not yet certain that a volcano ever existed on the continent of North America^ before the Cretaceous period ; for the published facts relating to supposed or alleged volcanic eruptions in the course of the Paleozoic ages are as well explained on the suppo- sition of outflows from fissures and tufa ejections under submarine conditions ; and none of the accounts present evidence of the former existence of a volcanic cone, that is, of an elevation pericentric in structure made by igneous ejections. Such cones in the tropical Pacific are now encircled by coral reefs as well as beds of detritus, and are thus in process of burial ; and so they might have been buried by limestone and other strata, if an actual fact in Paleozoic North America. During the Archaean, to its end, igneous ejections were on a vast scale. Even after the cooling had so far advanced that the sedimentary series in progress of deposition attained a thickness of many thousands of feet before a crisis of upturning and meta- morphism occurred, the heat from below, which was added to the heat of a dynamical source to produce the metarnorphism, was so far the greater of the two that fusion of the lower beds would have generally taken place ; and, as a consequence, great effusions of the melted rock through the overlying and much broken metamorphic beds, should have occurred in true bathylithic style, as the facts attest. But there is no evidence that they ever made Archaean volcanic cones. Archaean conditions gradually declined as Paleozoic time was passing, and so also did the power of making bathyliths. Later came the power, not merely of eruption through fissures, which has always existed, but also that of producing lofty volcanic cones. - The volcanoes also of the Andes are supposed to be chiefly of Tertiary origin. In Europe " the grandest volcanic phenomena were those of Oligo- cene (Lower Miocene) times, to this date belonging the basalts of Antrim, Mull, Skye, the Faroe Islands, and the older series of volcanic rocks in Ireland" (Geikie). The volcanic eruptions of Auvergne, the Eifel, and of Italy, Bohemia, and Hungary are referred mostly to the Tertiary. Asia, if the ranges of islands off its eastern and southern coasts are excluded, is peculiarly free from volcanoes. But the outflow of the Deccan trap in peninsular India, 200,000 square miles in area, was an event of the early Tertiary, and has been supposed to have occurred when the rising of the Himalayas began. The concurrence during the era from the Later Cretaceous to the close of the Tertiary of the most extensive erogenic work in the world's history, of the chief part of its continental elevation, and unprecedented igneous erup- tions, came when the earth's crust had reached a cooled condition that took all past time up ; to the present era for its production. The inquiry thence CENOZOIC TIME TERTIARY. arises whether these events are not in some way a consequence of the con- dition of the crust tljen for the first time reached. The conclusion has been before stated; it is here announced in its place in geological history. CLIMATE. The climate of the United States, even the northern, during the early Tertiary, was at least warm-temperate, as indicated by the fossil plants. There is evidence, as Asa Gray has remarked (1859, 1872), from the dis- tribution of Tertiary plants in the Arctic, made known by Heer and others,, and their relation to similar kinds in the eastern United States and in Asia, that the northern parts of the continents of America, Asia, and Europe were,. during that age, under a nearly common forest vegetation, with a compara- tively moderate climate. The genus Sequoia, of California, has its species, (as Heer has shown) in the Eocene of Greenland, Arctic America, Iceland, Spitzbergen, northern Europe ; and one Greenland species is very near the great Calif ornian S. gigantea; and these were successors to Arctic Cretaceous species. There were two species of Libocedrus in the Spitzbergen Miocene (Heer) ; and one (L. decurrens Heer) now lives with the Redwoods of Cali- fornia, while the other occurs in the Andes of Chile. Gray adds that the common Taxodium, or Cypress, of the Southern States, occurs fossil in the Miocene of Spitzbergen, Greenland, and Alaska as well as Europe, and also,, according to Lesquereux, in the Rocky Mountain Miocene. The Arctic Miocene is now made by Dawson and others probably Eocene in age. Europe evidently passed through a series of changes in its climate, from tropical to temperate. According to Von Ettingshausen, the Eocene flora of the Tyrol indicates a mean temperature between 74 and 81 F. ; and the-, species are largely Australian in character. The numerous Palms in England, at the same period, indicate a climate but little cooler. The Miocene flora of the vicinity of Vienna the same author pronounces to be subtropical, or to correspond to a temperature between 68 and 79 F. ; it most resembles that of subtropical America. Farther north in Europe, the flora indicates the warm-temperate climate characterizing the North American Tertiary ; and it is also prominently North American in its types. In the Pliocene, the climate was cooler still, and approximated to that of the existing world. The North American feature of the Miocene forests of Europe was proba- bly owing to migration from America through the Arctic regions, and not from Europe ; for a number of the European species, as shown by Lesque- reux existed already in the American Laramie and Eocene. The Australian feature also may have been a result of migration, but from the opposite direction. The Indian Ocean currents favor migration northward, along the borders of Asia, and not that in the opposite direction. What was the temperature of North America and the other continents at the close of the Tertiary, as a consequence of the addition of thousands of feet, and in some regions, of tens of thousands, to the height of the land, is, to be learned from the events of the following era, the Quaternary. 940 HISTORICAL GEOLOGY. QUATERNARY ERA, OR ERA OF MAN. Hitherto, along the ages, to the close of the Tertiary period, the conti- nent of North America had been extending its foundations and dry land southward to the Gulf, southeastward to the Atlantic, and southwestward to the Pacific, chiefly through marine depositions. The scene of prominent action now changes. The Quaternary phenomena are mainly those that pertain to the continental surface ; and this general fact is true for all the y continents, north and south. Through the making of the great mountain- ranges in the era just passed, and the raising of them to icy altitudes, and by the growth of the continents to their full limits, the water-power of the world had been vastly increased, and this was the chief working agency. Rivers had become of continental extent, and glaciers had gathered about the loftier mountains. These agencies, so eminently characteristic of the new era, were the means of finishing off the earth's physical arrangements. The Quaternary era opens with a glacial period. "The existence at this time of an epoch of unusual cold was a natural sequence to the vast amount of elevation and mountain-making that had been going on in the Tertiary over all the continents ; for this upward movement would necessarily have resulted in increasingly cold climates over the earth." (D., 1881.) The following are the periods of the Quaternary : 3. RECENT PERIOD. A moderate elevation of the land where depressed in the preceding period. Mammals of existing species. 2. CHAMPLAIN PERIOD. Depression of lands that were glaciated in the Glacial period; amelioration of climates; final disappearance of the ice ; great river floods and lakes, and fluvial and lacustrine deposits. Mammals of the warm temperate zone over parts of the previously glaciated regions, their species largely extinct. 1. GLACIAL PERIOD. Increased elevation of the land over wide regions in higher latitudes ; climate in these latitudes of low temperature and abundant precipitation, and consequently, the production of glaciers, and a wide-spread glaciation of the frigid lands, with the exclusion of all life except that of icy regions. The Glacial and Champlain periods were united by Lyell, in his later works, Tinder the general name of the PLEISTOCENE ; and thus the Quaternary era or the Post-Tertiary, as he named it was divided into the PLEISTO- CENE and RECENT periods. The term Pleistocene is used beyond in this sense. Lyell used the term Post- Tertiary for the formations subsequent to the Tertiary, and through many editions of his works divided it into Post-Pliocene and Recent. In the first edition of his Principles of Geology, published in 1830-33, the Tertiary was followed .simply by the division Recent; and the subjects of the Drift and Cave animals were CENOZOIC TIME QUATERNARY. 941 included under his second division of the Pliocene, called Newer Pliocene. In 1839, he proposed to substitute Pleistocene for Newer Pliocene, as a fourth division of the Tertiary, characterized by having about 95 per cent of the shells those of living species a larger proportion, as the name implies, than in the earlier part of the Pliocene. But the new name, as he states, was used by E. Forbes in 1846 and others for the Post-Pliocene instead of the Newer Pliocene, and he withdrew it. The perverted use of the term was partly owing to his retaining Glacial and related topics under the Newer Pliocene an arrange- ment which was continued into the 5th edition of his Manual of Elementary Geology, published in 1855. This was later changed. But in the 4th edition of the Antiquity of Man (1873) Pleistocene was finally adopted as a substitute for Post-Pliocene. The term Quaternary was used by Reboul, of France, in his work La Geologic de la Periode Quaternaire, 8vo., 1833. The division of the Post-Tertiary or Quaternary into the three periods mentioned above was presented by the Author in his address on "American Geological History" before the American Association, in August, 1855. (Amer. Jour. Sc., xxii., 305, 1856.) The names for these subdivisions then proposed were the Glacial, an epoch of elevation ; the Laurentian, an epoch of depression ; and the Terrace, an epoch of moderate elevation. In the first edition of this Geology (1863), the terms adopted were Glacial, Champlain, and Terrace. The two earlier periods, the Glacial and Champlain, have their more prominent characteristics displayed almost solely over high-latitude regions. They are not represented in tropical latitudes, or in warm temperate latitudes south of the parallel of 35, except locally about regions of lofty mountains. Moreover, deposits, like those of the Champlain period, were forming through the Glacial period along the southern border of the ice- sheet, owing to the melting that was going on, and the streams that were thereby made, especially in -the summers, and still more largely during temporary relaxations of the extreme cold. Further, the Mammals of temperate climates that spread northward over the previously glaciated area when the Champlain period opened, probably were all in existence during the middle and later parts of the Glacial period, after the epoch of extremest cold and maximum extension of the ice had passed, if not earlier. Glacial and Champlain phenomena were thus cotemporaneous. Nevertheless the periods stand well apart in the great epeirogenic movement, or change of level, that separates them, and in the continuation of Champlain con- ditions long after the ice had disappeared. Review of modern Glacial phenomena. The general phenomena and laws of Glacial Geology have been stated on pages 232-250, and illustrated in part by facts from an existing continental glacier that of Greenland. As there explained, the glacier moves over hills and ridges, up slopes as well as down, the pitch of its upper surface determining its direc- tion and rate of movement. It is greatly aided in excavating work by subglacial streams, that are far more effectual workers than ice ; which streams in Greenland, according to H. Rink, probably branch widely over the country, like a regular river-system, and have at times great volume. It gathers stones, gravel, and sand, for transportation, as well as large rock-masses. It abrades, through the stones at bottom, rocky surfaces passed over, and corrades the transported material, making rock-flour, sand, gravel, and smoothed or scratched stones out of the debris taken aboard ; and it may convert the finer material into clay. It deposits rock-flour and other debris from subglacial streams HISTORICAL GEOLOGY. : ; before and after escape from the ice-sheet, and makes clay-beds, sand-beds, moraine.s, drumlins, eskers. It makes glacier dams, producing thereby large lake-basins, by piling up the ice in -narrow gorges, or by pressure against the sides of valleys, and thus crossing and so closing open valleys ; and small lakes, liable to frequent discharges (page 238), by pressure of the ice against the side of the valley ; and, in times of melting and dissolution, it may build ice-dams in narrows along river channels out of blocks of floating ice and ac- companying glacier debris or drift, converting rivers into lakes. Further, the glacier, wherever it flows, usually leaves its tracks in scratched, grooved, or planed surfaces, upon the rocks passed over ; in scratched stones distributed through the drift material ; in large scattered bowlders that are traceable to a source in a direction opposite to that of the movement ; and also in its moraines and other drift accumulations. In the use of glacial scratches to determine the direction of movement of the ice-mass, it is always to be noted that the direction is quite sure to be diverted from that of the general ice- mass by valleys, or valley-like depressions in the surface beneath the glacier when they -are oblique to that course, even if the depression be small ; and that a knoll or low ledge of rock may have some divergent effect. Only scratches on high land, without such sources of error, are to be trusted. Moreover, with regard to traveled material or drift, the question is always to be asked whether water or floating ice may not have been the transporting agent. A glacier period in geological history was first recognized in 1837 by Louis Agassiz, before the Helvetic Society of Natural History, and in 1840 announced at the meeting of the British Association. Agassiz visited Scotland to verify his theory. He says in a letter to Professor Jamieson (1840): "I had scarcely arrived in Glasgow when I found remote traces of glaciers; and the nearer I approached the high mountain chains, the more distinct these became, until, at the foot of Ben Nevis and in the principal valleys, I discovered the most distinct moraines and polished rocky surfaces, just as in the valleys of the Swiss Alps." On Nov. 4, 1840, he brought the subject before the Geological Society of London. His theory of the drift was for awhile opposed by advocates of the Iceberg theo'ry, but it now has general acceptance. The earlier systematic observations on the drift in North America were made between 1832 and 1842 by E. Hitchcock, W. W. Mather, C. Whittlesey, James Hall, and others. Mather devotes many pages to the subject in his New York quarto report (1842), and states that he had gathered facts personally from New England to the meridian of 97 W. , ''traveling over 100,000 miles." His descriptions of Long Island drift, and that of the Coteau des Prairies and of many regions between, though he was not then a glacialist, are excellent ; and they are supplemented with results from other sources, and a long table giving the courses of glacial scratches over different parts of the country. Among the later investigators, over the Eastern and Central States, there are C. H. Hitchcock, whose work has been mainly in New England, and has been published in the Geological Reports of Vermont and New Hampshire, and elsewhere ; T. C. Chamberlin, whose papers have appeared in the Reports of the Wisconsin Geological Survey, those of the U. S. Geological Survey, and in other places; Warren Upham, who, after work in New England, has served as one of the geologists in the survey of Minnesota, and tem- porarily also in the Canadian Survey, and in each has extended his studies to the Winni- peg region in British America ; F. Leverett, R. D. Salisbury, J. S. Newberry, G. K. Gilbert, W. J. McGee, J. C. Branner, Carvill Lewis, G. F. Wright, and others. The author's pub- lications on American Glacial history range from 1856 to 1893, and those giving the results of special investigations, from 1870, onward. For the Rocky Mountains and the Pacific Slope within the United States, the most important publications are those of J. D. Whitney, Clarence King, I. C. Russell, J. S. .Newberry, and J. LeConte ; and for British America, those of Dawson, G. M. Dawson, R. Bell, R. G. McConnell, J. B. Tyrrell, and R. Chalmers. CENOZOIC TIME QUATERNARY. 943 1. GLACIAL PERIOD. AMERICAN. Three subdivisions or epochs, of the Glacial period, are recognized: '(1) the EARLY GLACIAL EPOCH, or that of the Advance of the Ice and its maximum extension; (2) the MIDDLE GLACIAL EPOCH, or that of the First Ketreat of the ice; (3) the LATER GLACIAL EPOCH, or that of the Final Retreat. 1. Epoch of the Advance. General Condition of the Continent during the Advance. Topographical and fluvial conditions. The continent, when the Ice age began, had its high mountains and full-grown rivers. The elevating of the -continental surface that was begun in the Tertiary had covered the land with running waters, and the new and vigorous streams made erosion their first work. The older streams, also, that had reached a level of no work, received new energy and were set to work deepening their channels, leaving the old flood grounds as terraces to mark progress. The time was especially favorable for pre-glacial erosion. In addition to this growth of rivers, forests took rapid possession of the continent, and faunas and floras greatly widened their range. As the cold and precipitation increased, the time finally came when the heat of summer was not sufficient to melt all the snows of the colder season, and then began glacial accumulation. For a while glaciers were confined to the higher mountains ; but gradually all glacier areas became united in one great continental ice-sheet, Greenland-like, with local glaciers only along some of the deeper terminal valleys. While thus spreading over the land, there were oscillations in the progress of the ice-sheet, as in modern glacier regions, determined by meteorological cycles, the 11-year cycle dependent on the cycle of the sun's spots, and a longer cycle of 35 to 50 years, as now in the Alps. And besides, there were other sources of meteorological change, causing longer halts and recessions in the ice-sheet, for which no explanation can yet be given. A large ice-sheet gives a temperature of 32 F. to the air above it, and this favors its perpetuity. But the southern margin, at the time of maximum advance, was in middle temperate latitudes with the tropics not far away ; and warm or hot winds, therefore, were at hand to produce large fluctuations in the extension of the ice with the changing seasons. Causes determining places of the flrst ice and of greatest accumulation. Since the ice would have accumulated most rapidly where abundant pre- cipitation and low temperature were combined, the region of earliest com- mencement and maximum accumulation would have been over the eastern portion of the continent toward the Atlantic. Along the coast region of 944 HISTORICAL GEOLOGY. New England and Canada the annual rainfall is now 45 to 50 inches a year,, and it was then probably still greater, perhaps 55 to 60 inches. Farther north, at the present time, the precipitation decreases while the cold increases. In northern Labrador the former is reduced to 20 inches. In Greenland, where ice is perpetual except within 30 to 60 miles of the coast, the mean annual precipitation is but 10 inches. The mean annual precipitation west of New England over three fourths of the state of New York is now 38 to 42 inches. But in the Mississippi valley, over Wisconsin, it varies from 32 to 38 inches ; and over the larger part of Minnesota, from 20 to 32 inches, while farther north in Manitoba it is mostly between 20 and 10 inches. Moreover, in the Continental Interior the summer isotherms make a long sweep north, that of the July mean of 70 F. extending beyond Lake Winnipeg, even to 56 N., which is 10 of latitude, or 700 miles, farther north than the position of the same isotherm over New England. Consequently, New England would have made a large accumulation long before the Mississippi valley in the same latitudes had any permanent ice. And after the ice had become permanent, it might have disappeared over the Interior while on the eastern border it was still accumulating. With the conditions in the Continental Interior so near the critical point, the ice-mass there would have responded readily to changes of temperature ; a meteorological change might have carried off the ice for a breadth of scores or hundreds of miles, which would have made no impres- sion in corresponding latitudes to the eastward. At the same time, in latitudes beyond 60 N., the precipitation might be too small for great accumulation and glacial movement. However great the cold became, the icy heights to windward were everywhere robbing the air of its moisture, and so leaving little for the regions to leeward. Southern limit of the ice. Under such various conditions the ice became distributed over the breadth of the continent from the Atlantic Ocean to the Pacific. The map of North America, Fig. 1548, shows the southern limit of the ice-sheet, as ascertained from the traces it left over the surface. The limit is indicated by the heavy line crossing the map from southeastern Massa- chusetts over southern Illinois and northern Montana to the Pacific coast. Its most eastern observed point is Nantucket ; thence, it extends along the islands south of New England, to Perth Amboy in New Jersey. Farther east and northeast its course was probably over George's Shoal, 150 miles east of Cape Cod, where the minimum depth is now but a few feet, and over the shoal region off Nova Scotia (by Sable Island) and Newfoundland. From Perth Amboy it crossed New Jersey and Pennsylvania obliquely, entered for a short distance western New York ; then bent south westward to southern Illinois. Beyond the Mississippi and the meridian of 97 W. it made a bend northward to 47 N., on account of the dry and warm summer climate of the Continental Interior, and near this parallel it reached the Pacific coast. But in the Rocky Mountain or Cordilleran region, it covered 40- 90 MAP OF NOBTCH AMERICA *r ILLUSTRATING THE PHENOMENA OF THE GLACIAL AND CHAMPLAIN PERIODS. Limit of ice sheet Moraines - < Mean direction of Glacial scratches \\\ ^ Former shore line of lakes 70 CENOZOIC TIME QUATERNARY. 945 the higher summits at intervals, even as far south as New Mexico. Again, there were isolated glacier regions along the Cascade Range and the Sierra Nevada, about Rainier, St. Helens, Hood, Shasta, Lyell, and other summits ; and in the Great Basin, on Jeff Davis Peak, the East Humboldt Range, Shoshone Range, and West Humboldt Range. Shrunken relics of the old glaciers still linger about the Wind River Mountains in Wyoming; on Mount Lyell and Mount Dana in the Sierra Nevada ; and on Shasta, Rainier, and other summits of the Pacific coast region. East of the summit range of the Rocky Mountains in British America, the limit between the eastern drift, or that from the region east of Lake Winnipeg, and the western, or that of the mountains beyond, has the posi- tion shown by the dotted line on the map, Fig. 1548, the height being 3000 to 3700 feet above sea level. There was also a northern limit to glaciation in northwestern America, according to G. M. Dawson. The line crossed the plateau region of British Columbia, between 60 and 64 N., and consequently Alaska was uncovered a fact confirmed by the more recent observations of Dall and Russell. Greenland had probably no more ice than now. The details on the map (Fig. 1548) with reference to the moraines from the Mississippi to New Jersey have been obtained chiefly from published and unpublished notes of Chainberlin and Leverett ; those over Iowa and Minnesota, from W. Upham ; those about the Coteau des Prairies, from I. E. Todd ; and those farther north, from G. M. Dawson ; for the position of the southern ice-limit, or Moraine line A, from H. C. Lewis, Report Z ; The Terminal Moraine in Pennsylvania, 1884', from G. F. Wright ; for the line westward to the Mississippi, Lewis's Report Z, and also Wright's Ice Age, etc. ; for the positions of the glacial lakes of Manitoba, from W. Upham ; those of the lakes of the Great Basin, from G. K. Gilbert and I. C. Russell; for the glacial striae over New England, from C. H. Hitchcock mainly ; and those of other regions from Chamberlin's map, lih Ann. Hep. U. S. G. S., and other sources. Condition outside of the Ice-limit. Forced migration. South of the Ice- limit, the precipitation was probably as heavy as to the north of it. But it made only deep snows about the Appalachians and other low mountains, and contributed water abundantly to rivers and lakes. Over a narrow belt near the front, there would have been marshes and ponds with Arctic vege- tation, and cold-climate Mammals, which had been driven southward. Several of the emigrant plants still remain and thrive on the summits of the mountains of both eastern and western North America. Thirty-seven species, according to Asa Gray, occur on the White Mountains of New Hampshire, and part of them also on the Adirondacks and Green Mountains. Out of 27 species observed by the Jensen expedition on a Greenland Nunatak in 1878, the White Mountain flora includes, according to Gray, the Grasses Luzula hyperborea and Trisetum subspicatum, the Sorrel, Oxyria digyna, the Moss-like Heath, Cassiope hypnoides, and the Moss-like Catchfly, Silene acaulis. Sedum rhodiola, a subalpine species, occurs on cliffs of the Dela- ware, below Easton, Pa. ; Saxifraga oppositifolia Linn., on Mount Willoughby, DANA'S MANUAL 60 946 HISTORICAL GEOLOGY. in Vermont ; Arenaria Gronlandica, on the White Mountains, the Catskills, Shawangunk Mountain, and, in the form of A. glabra Michx*, on the Alle- ghanies of Carolina ; Scirpus ccespitosus in North Carolina, a patch remain- ing on Roan Mountain, and Nephroma arcticum, and other northern Lichens, with Lycopodium selago on the highest Alleghanies. Even freshwater shells of the Unio family were among the immigrants, as C. T. Stimson has found by a study of fossil shells from near Toronto. Scudder has shown that in North America the fossil Coleopterous Insects of deposits laid down in the Glacial period are very nearly all of extinct species, while those from peat beds of later origin are, with a rare exception, existing species. The bones of the Reindeer have occasionally been found in the valley drift. Two bones, referred by Marsh to the Arctic Reindeer, Rangifer tarandus, were found in the lower clay-beds of the Quinnipiac River, three miles north of New Haven, and others have been reported from near Vincen- town, N. J. Other remains, but possibly of the R. caribou, have been found near Sing Sing, N.Y., in Kentucky at Big-bone Lick, and on Racket River in northern New York. The region farther south abounded, no doubt, in the beasts, birds, and other species of a temperate climate. With so long a glacial front in lati- tudes of 40 to 35, at the time of greatest extension, the extreme cold would have swept at times over the south, and have probably excluded from the region north of Florida tropical and subtropical species, excepting migrating kinds. Elevation of the Continent. The evidence that the continent, especially over its northern portions and along the mountain borders, continued its rise above the sea level after the Tertiary period is based largely on the facts relating to river channels, fiords, and Arctic migrations between Europe or Asia and America. Evidence from river channels and fiords. Near and beneath the southern margin of the ice, over the interior of the continent, many river channels, as proved by borings, have a depth of 100 to 400 feet below their present bed. These deep gorges are filled with drift, thus making it certain that the excavation was completed in the Glacial period. Newberry states that all the river valleys of Ohio are examples. The Cuyahoga, which is one of them, has, where it enters Lake Erie, its bottom 200 feet below the present bed, and this continues for 20 miles up the stream. The valleys of northern Pennsylvania are other examples, and according to Carll and White the depth of the drift-filling is, in some cases, 300 to 400 feet. At the west end of Lake Ontario, the Dundas gorge has been proved by borings to descend 227 feet below the sea level, or nearly half as far as the deepest part of Lake Ontario, the material penetrated by the boring being drift (J. W. Spencer). It is inferred that the lake was above the sea level in the period, and that a river flowed along its bottom, either eastward or westward, CENOZOIC TIME QUATERNARY. 947 and produced the excavation. The depth of Lake Ontario is 738 feet, 492 of which are below tide level; and hence the minimum elevation that would give the same slope to the water as now was 738 feet. As shown on the map on page 201, this Ontario River (or the line of greatest depth) was near the south shore ; and the depression had a high declivity on that side which was very steep for the first 500 feet. Similar conclusions may be drawn from all the Great Lakes ; for they are generally believed to have been excavated by running waters during the Glacial period. The map on the page referred to has marked upon it the outlines of the drainage areas of the several lakes, the deep-water line, and the position of the point of maxi- mum depth ; and Schermerhorn remarks that the deep-water line of each is near the center of the area of drainage. The Lake Superior basin descends 407 feet below sea level; the Michigan, 289 feet; the Huron, 121 feet. For fluvial excavation, the elevation must have been not only that which would raise the basins above sea level, but to a height above the surrounding land that would enable even the bottom waters to flow out of the drainage basins ; and to pass, not the existing drainage barriers, but the barriers of the Glacial period, when the land in the vicinity was far above its present level. A change of level is also proved by the reversed flow of some streams. 'Carll and others have shown that the Pennsylvania rivers, the Alleghany and Beaver, then flowed northward into Lake Erie, proving that the land dipped toward the Erie basin. In the Beaver River channel in western Penn- sylvania, now a tributary of the Ohio, the filling of drift, according to Foshay and Mice (1890), is only 60 feet deep at its mouth ; but 20 miles above, it is 200 feet, according thus with the view that its drainage, as shown by Carll for the Alleghany, had been reversed. The Tionesta and Conewango basins, according to Carll, participated in reversed Erie-ward pitch. Facts on this subject of reversed drainage are presented by Chamberlin in a paper of 1894, along with illustrating maps. Moreover, Gilbert pointed out in 1871, that the Maumee River, now emptying into the west end of Lake Erie, then flowed westward, and joined the Wabash, and thus made the lake a tributary to the Ohio. He found the evidence both in westward glacial scratches and moraines, and in lake terraces. It is possible that a Huron River made another Ohio tributary. Again, Lake Winnipeg, as pointed out by G. K. Warren (Rep. U. S. Engineer Dept, 1867, 1874, and Am. Jour. Sc., xvi:, 417, 1878), which now discharges into Hudson Bay by the short Nelson River, formerly discharged into the Mississippi, and, with the Saskatchewan River, was its northern head waters. At the present time, the level of the lake is about 260 feet ; too low for a southward flow. The divide is in Minnesota between Big Stone Lake, the head waters of Minnesota River, and Lake Traverse, the head waters of Red River of the North, a Winnipeg tributary. These two little lakes are but a few miles apart and differ but eight feet in level. The valley of Red River and that of the Minnesota were found by Warren to be con- tinuous, and to be a great valley across the divides, 125 to 150 feet deep, and 948 HISTORICAL GEOLOGY. a mile and a half wide, enlarging southward to its junction with the Missis- sippi valley; and, in contrast, the valley of the Mississippi north of this junction is small. He thus obtained positive evidence that the valley and river from Winnipeg southward was not long since one, and that the conti- nental level was then such as would give the southward flow to the waters. To reproduce now this slope would require a rise of the Winnipeg region (or a sinking of the divide) amounting to about 260 feet ; and to give the waters also a pitch of half a foot a mile, an additional 165 feet. The former existence of this greater Mississippi is also shown by the fact that fresh- water shells of the Winnipeg region also live in the Mississippi. Warren also suggested that Lake Michigan at the same time, owing to the same northern uplift, discharged by the Illinois Eiver into the Mississippi its broad and deep valley widening in the vicinity of the lake in accordance with this direction of flow. The changes about all the Great Lakes were such as tended to give them probably independent outlets. The channels that now unite them are all shallow, generally not exceeding 50 feet. Further proof of high-latitude elevation in the Glacial period is afforded by the river-valleys of the coast region now filled with water, that is the fiords, and the multitudes of islands, and many channels among islands, along fiord coasts. The fiords of Maine, Labrador, Newfoundland, Greenland, British. Columbia and Alaska, and those of Scandinavia, western South America south of 41, of Tasmania and South Australia, are such valleys, and they all are confined to Glacial latitudes. None occur on southern Africa, which reaches only to 34 22' S. They were made when the land stood high enough for the denudation of the rocky coast region ; and in view of the great lift the continent and other continents were having in the Later Ter- tiary time and during the opening Quaternary, it is a reasonable supposition, as the author pointed out in 1856, that the work of excavation should have gone forward during the Glacial period. It cannot be affirmed that the work of denudation was not begun during emergencies long before ; but if so, this period of so widely extended elevation, probably the greatest in the world's history, must have finished the work. Some of the fiords of the Atlantic coast between southern Maine and Hudson Bay have been found by soundings, as stated by Spencer, to have depths of 2000 to 3670 feet below the sea level ; and the St. Lawrence chan- nel below the Saguenay has afforded soundings of 1104 and 1878 feet. The Saguenay gorge descends 300 to 840 feet below the sea level and rises 1500 feet above it. They compare well with the fiords of the Scandinavian coast, several of which are above 2000 feet in depth, and one, the Sogne Fiord, 4020 feet. The fiords of a coast differ widely in breadth and depth; and the deepest and largest were probably those channels that had been excavated to the sea level, during the time of emergence, while others are the shallower gorges of the denuded region. They have generally at present a bottom of drift CENOZOIC TIME QUATERNARY. 949 or other detritus, so that the actual depth of excavation may much exceed that obtained by soundings. From such facts it is reasonable to estimate the elevation of portions of British North America along the Canadian watershed, or the great Ice- plateau, to have been at least 3000 feet above the present level. This subject has been recently well discussed by Upham, with this estimate as his conclusion. The author, in 1871, suggested 5000 feet, and this may not be too high for some portions of the Canadian region of highest ice. With 3000 feet for the Canada watershed south of Hudson Bay, this bay must have been largely dry land. Along the coast of Maine the elevation indi- cated is less than a thousand feet. South of Maine, on the New England coast, other fiord-like indentations of the coast exist in Narragansett Bay, R.I., and the gorge of the Thames, from New London to Norwich, Conn. Besides these, there are pot-holes in the gneiss of islands off the Connecticut coast ; and those of the Thimble Islands, in the bay of Stony Creek, show that this bay was formerly crossed and probably excavated by a freshwater stream. The great depth of the bays on the north side of Long Island, 50 to 65 feet notwithstanding the later drift deposits over the region, is further proof of elevation. The amount for southern New England and Long Island could not have been less than 150 feet (D., 1870). With this elevation, Long Island Sound in the Ice period would have been, instead of an arm of the sea, the channel of a river tributary to the larger Connecticut River; and Long Island with New York on the west side and the south coast of New England on the east would have been continuous dry land. (See map, page 18.) The soundings of the Sound and of the waters south of Long Island are shown on this map, and also more fully in Am. Jour. $., xl., 1890, with explanations in the same volume. If the fiords of the coast are proof of elevation, the absence of them farther south should be probable evidence of little elevation or none. The submarine Hudson River channel (map, page 18) indicates a former emerged condition of the sea bottom, requiring an elevation of the region and the adjoining coast of 2800', judging from the deepest part ; and it has been inferred by Lindenkohl and Upham that this elevation took place in the Glacial period. But the facts from the New England coast indicate only small elevations. Moreover, the origin of the submerged Hudson River channel appears to have been of much earlier date, as has been explained on page 744. J. W. Spencer has inferred from the Coast Survey maps that there are submarine river channels off the mouths of several of the rivers of the coast south of Cape Hatteras, and in the Gulf of Mexico, the Mississippi included. But no satisfactory evidence of such channels exists on these charts, in the opinion of officers of the Coast Survey. G. M. Dawson states, with reference to the fiord region of western America, that the land in the Pliocene stood relatively to the Pacific about 900 feet higher than now ; and he concludes that the fiords were shaped and enlarged locally during the following Glacial period, when the amount of elevation was still further increased. The submerged river channels of the Pacific coast of North America, on the coast of California, as described by G. Davidson (1887), descending to depths of 2400, 3120, and 2700 feet, indicate a higher level of the region of 2500 to 3000 feet, and probably during the Glacial period. 950 HISTORICAL GEOLOGY, Evidence from Mammalian migration between North America and Europe or Asia. Another argument for the elevation of the land of the higher latitudes, and particularly the polar, has been drawn from the fact that the migration of Plants and Mammals took place between the two continents in 1549. Bathymetric map of the Arctic seas, reduced from the chart of the U. S. Topographic Department. the Quaternary. The migrating species include the Keindeer, Moose, Elk, Polar Bear, Grizzly Bear (the Brown Bear, Ursus Arctos of Europe, being regarded as identical with the Grizzly), Beaver, and probably other Mammals. There were also even migrating Unios, one species, Margaritana margaritifera, CENOZOIC TIME QUATERNARY. 951 occurring in northern Europe and Asia, and also in North. America from British Columbia to California, and on the east from eastern Canada to Pennsylvania. These facts prove land communication. Dry land at Bering Straits would have sufficed, and required an elevation of but 200 feet. But there was probably connection also across from Europe to Arctic America. The connection was prolonged for the polar part into the Champlain period. The accompanying bathymetric map will aid in appreciating the effects of a change of land in the Arctic regions. 1 An elevation now of but 1000 feet would add certainly 700 to 1000 miles to the width in a northward direc- tion of Europe and Asia, putting Franz Joseph Land along the northern margin, and, perhaps, much of the unsounded region farther north. Only about 650 miles intervene between northern Spitsbergen and Greenland. The map shows further that an elevation of 3000 feet would make a dry land passage from Norway by Britain to Greenland, drying up the German Sea, and probably nearly the whole of the Arctic Ocean. The waters north of Melville and Bathurst lands may be as shallow as those north of Lapland. Apparent upward change due to change in tvater level. Part of the appar- ent upward change of level may have been only a downward change in the water level of the ocean. Agassiz, holding that ice covered nearly the whole continental area of the globe, argued that the abstracting of water from the ocean to make ice would have occasioned a large continental emergence. But the proportion that was actually covered was so small relatively to the whole surface of the globe that the consequent emergence could not have exceeded 60 feet. South America has but a narrow strip in glacial latitudes, and the ice areas of Australia and New Zealand were very small. Another cause affecting the water level was the attraction of the mass of the high ice-plateau. It acted on the ocean's waters like that of any other elevated land-mass, by drawing the water up over the land, and thus occa- sional actual submergence. The effect was, therefore, opposite to that from the loss of water for making ice. Height, Thickness, and Flow of the Ice. Evidence from glacial scratches and transported bowlders. On the map, Fig. 1548, the mean directions of glacial scratches are marked by arrows, and these directions are taken in all cases, as far as could be ascertained, from the results of observations over the higher land of a region, away from the influence of valleys or depressions. Positive facts as to the height of the ice in particular localities are few. Scratches observed by E. Hitchcock on Mount Washington, in 1841, put the limit, in that part of New England, above 5500 feet ; and the more recent discovery by C. H. Hitchcock (1875) of transported bowlders, some of them 90 pounds in weight, near the summit of the mountain (6293 feet above the sea level), proves that the mountain was completely covered, and that the 1 The depths, on the map, are given in 100 fathoms, 5 signifying 500 fathoms or 3000 feet, and .5, 50 fathoms. The arrows show courses of marine currents. 952 HISTORICAL GEOLOGY. height of the ice was not less than 6500 feet. Mount Mansfield, the highest summit of the Green Mountains, Vt., 4389 feet high, was wholly under ice, as proved by transported bowlders. Mount Katahdin, in Maine, has bowlders to a height of 4700 feet. The Catskills have marks of glaciation to a height of 3200 feet (Smock, 1873), and Elk Mountain, in northeastern Pennsylvania, to a height of 2700 feet (Branner). It is probable that Mount Katahdin and some peaks in the Catskills were " Nunataks." Evidence from the pitch required for movement. From the probable pitch of the upper surface of the ice-sheet required for movement, estimates may be obtained of the height of the ice in other regions. In Greenland, flow takes place when the slope of the surface of the ice is but 26', or 40 feet to the mile = 1 : 132 ; and Helland obtained for the maximum rate of flow, where the slope of surface was less than half a degree, 20 meters per day. If the rate of slope between the summit over the White Mountains and the southeast side of Martha's Vineyard (which was the course of movement) was only 30 feet per mile, then the height of the ice-surface over these mountains was about 6500 feet; and it would have been a third larger, if 40 feet per mile. A like calculation for the Adiron- dacks gives a height of about 7000 feet. The height of the ice on the Cats- kill Mountains, mentioned above, 3200 feet, corresponds with the latter estimate ; for the distance of these mountains from the southern limit of the ice, near Perth Amboy, N.J., is nearly one half as great as that of the Adirondack summits. Moreover, drifted stones of hypersthene rock from the Adirondacks occur upon them, as stated by Mather. The ice of the Adirondack region flowed south-southeastward, over eastern Connecticut, into what might be called the realm of the White Mountains, and it did this notwithstanding the obstructing Green Mountain range on the route; and this is evidence that the Adirondack part of the ice- plateau was the higher. By the same kind of evidence, the height of the watershed between the St. Lawrence and Hudson Bay, toward which the scratches over northern and northwestern New England point, is found to be 13,000 feet. But this part of the Laurentide ice-plateau may have been nearly level for a long distance south of its summit, so that the height may not have exceeded 10,000 feet. Again, Mount Katahdin is 60 miles from the summit of the mountain range that stands between Maine and the St. Lawrence River ; and hence the height of the ice over this range was about 6500 feet, if 4700 feet at Katahdin. Across Wisconsin the distance from the south shore of Lake Superior to the southern ice-limit is not less than 500 miles, and a slope of but 20 feet a mile would give a height at the lake of 10,000 feet. Part of the 10,000 feet was made by the greater height of the land in the Lake Superior region. The difference in elevation now is about 1000 feet. It was probably greater in the Glacial period, through the increased elevation of the Lake Superior region. As reported by C. A. White, a mass of native copper, of 30 pounds weight, was taken from the drift of southern Iowa, Lucas County, CENOZOIC TIME QUATERNARY. 953 and other smaller pieces from other parts of the state, and also from the southern part of Illinois. It came from the Keweenaw Copper region, in northern Michigan, south of Lake Superior, for this is the only possible source. The distance is about 450 miles. A slope of 20 feet a mile, noting that the locality in Lucas County has a height of 1000 feet, would give, for the height of the ice-surface in the Keweenaw region, 10,000 feet. The present height of the land in this region is about 1500 feet ; it was possibly then 3500 feet. It may be thought that detached ice, floating down the Mississippi, might have transported the copper. But the Lucas County locality is about 120 miles west of this river, and 500 feet higher than the land at Burlington, Iowa, a Mississippi town. The distribution of copper in the drift has been attributed to the Indians. But in all probability they would have gathered it from the drift, and thus diminished the amount rather than increased it. The distance of travel appears to have been still greater in British America. Along a line from the Laurentide ice-plateau in Canada, across the region of Lake Winnipeg, to the western limit of the drift, even a slope of 12 feet a mile would make the height of the Laurentide ice-surface -over 8,000 feet. The drift at this limit contains Archaean bowlders of varying .size up to a length of 40 feet, which proves its eastern origin. The rocks on the west side of Lake Winnipeg are Archaean. With the slope at a minimum, the rate of transportation per century would be at a minimum, and the time for corrasion and decomposition, or the wearing out of stones, at a maximum; so that the material for the terminal moraine, under such circumstances, should be at a minimum. The thickness of the ice in any place equaled the total height less the elevation of the land beneath; as the latter is an unknown quantity, the actual thickness is seldom obtainable. A thickness of ice of 4000 to 5000 feet probably existed along the Canada watershed, in northern New England and New York, and west of New York, in the region of the more northern of the Great Lakes ; and a thickness of 1000 to 3000 feet was common over the region to the southward. One large area of snows and thin ice not thick enough to participate in the glacier movement existed in the midst of the moving glaciers of Wisconsin, Iowa, and Minnesota. It is now driftless, and has an area of 12,000 square miles (map, Fig. 1548). J. G. Percival, in his survey of Wis- consin, first recognized its driftless character, and J. D. Whitney, in 1862, described and mapped it. It is now an area of minimum winter precipi- tation. The ice flowed either side of it, passing on the west side over the east border of Iowa. Courses of glacial scratches in the White Mountain region, New Hampshire, according to C. H. Hitchcock : Near Lake of the Clouds, 5000' to 5200' above the sea, S. 34-54 E.; on the N. side, near top of Mount Clinton, 4430', 17 m. W. of Mount Washington, S. 50- 54 E. ; and on S. peak of Mount Clinton, 4320', S. 54 E. ; between Mount Pleasant and Mount Franklin, 4400', S. 30 E. ; between Mount Pleasant and Mount Clinton, 4050', 954 HISTORICAL GEOLOGY. S. 30 E. ; S. end of Mount Webster, S. 37 E. ; top of Mount Webster, 4000', S. 30 E.; top of Moosilauke, 4811', S. 22 E. Further, on Mount Abraham, in Maine, the direction found is S. 59 E. From the White Mountains to the coast of Maine, along by Portland and the mouth of the Kennebec, the distance is but 70 miles ; and hence, supposing the pitch of the surface the same as to Nantucket, the foot of the glacier in that direction, as remarked long since by Agassiz, was over the shoals off the coast of Maine, south of Nova Scotia, then probably an emerged area, and the depth of ice over this part of Maine was at the least 4000'. The direction of the scratches (see map) over western New England is testimony as to the Adirondack source of the ice. The following are observed facts : Over high western Connecticut, 1000' to 1200' above the sea, in Warren and Litchfield, S. 29 E. (D.); in Newtown, S. 32 E. (D.) ; in Sharon, S. 33-36 E. (D.); in Cornwall, S. 33-36 E. (D.); near Norfolk, S. 20-25 E. (Mather); on Mount Tom, near Litchfield, S. 17-22 E. (Hitchcock) ; in Goshen, S. 23 and S. 28 E. (H. Norton) ; on Kent Moun- tain, S. 19 E. ; and S. of Kent, S. 38 E. (D.); bowlders, from Canaan, of limestone con- taining canaanite, found 5 m. W. of New Haven, S. 16 E. (D.). In western Massachusetts, on Mount Washington, in its southwest corner, on the top of its summit peak Mount Everett, 2624' high, S. 18 E. (Hitchcock), S. 27 E. (D.) ; on top of the ridge Tom Ball, nearly N. of Mount Washington, S. 43 E. ; on the Taconic Range, W. of Richmond, S. 53-S. 70 E. ; on top of Lenox Mountain, between Stockbridge and Richmond, S. 41-45E. (Benton); E. slope of Taconic Range, near Pittsfield, S. 50 E. (D.); on the mountain between Otis and Becket, about SE. (Hitchcock). The bowlder train (page 959) over Richmond and Lenox has the course S. 45 E. west of Richmond, and S. 35 E. from Richmond through Lenox. Over the higher part of Vermont (from E. and C. H. Hitchcock's Vermont Hep.), mostly S. 30 E.-S. 55 E. the greatest to the northward ; in the southern portion of Ver- mont, in Windham, S. 28 E. ; in Wilmington, S. 29-39 E. ; in central Vermont, West Hancock, S. 50 E., Ripton, S. 60 E. ; in northern Vermont, on Camel's Hump, 4077' above the sea, S. 55 E., on Mount Mansfield, 4389', S. 55 E. ; on Jay's Peak, north of the last, S. 50 E. In higher parts of eastern New York, in Dutchess County, mostly S. 15-30E. (Mather) ; near Arthursville^ S.24E. (D.) ; in Putnam County, near Patterson, S. 17- 22 E. (Mather) ; in Columbia County, north of Dutchess, S. 18-30E., and on moun- tain top east of Shaker village, S. 45 E. ; beginning of Richmond bowlder train on the borders of Lebanon and Canaan, S. 55-45E. (Benton). In northern Pennsylvania, J. C. Branner obtained for striae on Pocono Mountain, west of Carbondale, a mean course of about S. 20 W.-S. 30 W. ; and on the summit of Bald Mountain west of Scranton, S. 10 W.-S. 33 W. The facts prove that from all western New England the flow was from the northwest- ward, across the Taconic Range and the Green Mountains, and in a direction from the Adirondack region, or the more elevated Lauren tide region beyond it. The distance from the Adirondack part of the plateau to the southwest margin of the lobe in western New York is about 200 miles, or 150 if the Adirondack plateau extends 50 miles west of Mount Marcy. It is about 250 miles to the ice-lirnit south of New York, and nearly the same to southern Long Island in the line over New Haven ; and about 220 miles from the White Mountain center to the southeast side of Nantucket. It is to be noted, however, that the position of the margin in western New York was 1500' above the sea level. A bluff facing the water of Lake Cayuga, about a mile north of Ithaca, according to H. S.Williams, in a region where scratches, flutings, and planings of the rocks are exhibited on a grand scale, has its whole vertical face marked with scratches that have a descending CENOZOIC TIME QUATERNARY. 955 course of about 25 to 30. The narrow lake trends about S. by W., not far from the direction of movement in the ice-sheet over the region. Over Manitoba, the following courses of scratches are reported by S. B. Tyrrell : About Lake Manitoba, S. to S. 13 E. ; about Lake Winnipegosis, S. 13 E. to S. 58 W. ; about Swan Lake, west of Winnipegosis, S. 48-53 W. ; on Red Deer River, S. 68- 78 W. ; Grand Rapids on the Saskatchewan, S. 2-62 W. ; at Roche-rouge, S. 12 W. ; Cedar Lake, S. 19-39 W. The southward and southeasterly course is evidently due to a valley movement along the lakes. For others, over the interior of North America, see Upham's paper on Lake Agassiz, Can. Geol. Bep. for 1888-1889, and other Reports of the Canada Geological Survey. In the use of scratches to determine direction of flow, the directions on page 942 should be observed. When scratches having different courses occur at the same locality, it is also to be remembered that direction of general movement in the ice-mass depends on the slope of the upper surface, as is true for any liquid ; and therefore that the thinning of the ice from melting may change the direction of movement at bottom. But where thinning has diminished the slope of the ice-surface below the angle required for flow, the ice is that only of a dead glacier. Bowlders were observed in Northampton and Monroe counties, Pa., by Lewis and Wright, which must have come from the Adirondacks. One of them of " labradorite syenyte," 2i' in diameter, was found in Upper Mount Bethel just south of Kittatinny Mountain; another, similar, measuring 4' x 3' x 3', on the moraine near Taylorsburg,, between Kittatinny Mountain and Pocono Mountain ; and another, of gray Adirondack granite, containing magnetite, near Fork's Station, in Paradise, 5 miles north of Pocono summit, at a height of 1550' ; and bowlders of gneiss are abundant over the Pocono plateau, 2000' above sea level. (Geol. Eep. Pa., vol. Z, On the Terminal Moraine in Pa. and N. Y. , by H. C. Lewis, 1884, with an Appendix on the Terminal Moraine in Ohio and Kentucky, by G. F. Wright.) General direction of flow. " From the Laurentlde ice-plateau, or that which covered the Canada watershed and extended westward and north- ward, the flow was not only eastward and westward, but also northward, from its northern part toward the Arctic seas ; and along the great eastward bend in the plateau over Canada south of Hudson Bay to Labrador, it was south- westward on the western part, and farther east, southward and southeast- ward. The observed courses of transported stones and lines of abrasion are the means of locating the summit region of the ice-plateau. High mountains outside the plateau also influenced the flow, for they are regions of greatest precipitation. The White Mountains, Green Mountains, and Adirondacks, combined into a common plateau by the ice, was one of these mountain regions, apparently determining southeastward directions of movement over New England and southwestward over Pennsylvania and much of New York. In western New York and over the higher parts of Ohio the flow was again east of south ; but beyond Indiana to Dakota the direction was in general southward and southwestward, as if from an ice- plateau in the Lake Superior region. But above these plateaus, and farther north, dominated the higher Laurentide ice-plateau, which appears to have been the chief source of movement southward for the region during the time of maximum ice, although there were many subordinate sources. D56 HISTOKICAL GEOLOGY. In the glaciated area along the Rocky Mountain Range of British America called the " Cordillera area " by G. M. Dawson, and the region between this range and the coast, the movement of the ice was for the larger part south- eastward. But a northern part, north of 60-65 N., moved northwestward, .and central portions escaped westward through passes in the mountain ranges near the coast (G. M. Dawson) . About the Wisconsin driftless area the scratches over the surface east of it, according to Chamberlin and Leverett, mostly point westward or west- south westward, toward the area, in concordance with the fact that the area was that of a depression in the ice-sheet, so that the slope of the ice-surface was toward it. And to the south of it the same course is continued, show- ing that the depression in the ice-sheet was lengthened southward. But on the same authority, there was also an interval when the movement south of the area, as proved by the transported material, was reversed, or from Iowa into Illinois. To the eastward, the ice-sheet, when at its maximum stage, extended southward in a broad convexity or lobe over New England and New York. {See map.) This was due in part to the general topographic form of the surface, but more directly to the position and height of the White Mountain and Adirondack ice-plateau, the head of the ice-movement. But besides this, Pennsylvania and southwestern New York were under the lee of the ice- covered Adirondacks and Catskills, and it is for this reason, apparently, that over the former state the southern limit took its northwestward course into New York ; a course which has no correspondence with the lines on a modern rain chart. The flow was also guided in part by large lake depressions, and especially when these were near the border, as was the case during the progress of the Glacial period. Moreover, the flow of the lower ice was always influenced locally by the topographic form of the surface, and particularly by the courses of large river valleys as stated on page 247. Such valleys have their valley drift and scratches, as proof of the valley movement. This movement, as in the case of that along the Connecticut River valley, has sometimes been attributed to a local glacier after the retreat of the ice-sheet. But the Con- necticut, for the 200 miles from Haverhill, N.H., to the Sound, has a pitch of only two feet a mile. More than 50 feet a mile would be required for move- ment, and this would demand a height at Haverhill of 10,000 feet, which could not be unless the greatest of the earth's mountains existed there. A length of 200 miles in a local glacier along an open valley is more than three times greater than now exists. The Connecticut River valley is a good example of the effect of large valleys, oblique in direction to the general movement of the ice, in carrying off the lower ice which lay in the depression, while the upper ice continued part way, or wholly, across it. Its direc- tion along southern Vermont and over Massachusetts and Connecticut to New Haven is S. 8-16 W., while that of the general glacier movement was S. 30-50 E. The flowing bottom ice, within the confines of the valley, carried along for distribution almost solely CENOZOIC TIME QUATERNARY. 957 stones from valley rocks chiefly trap and red sandstone and made scratches in the direction of the valley, while the upper ice left similar evidence of its direction of flow, S. 30-50 E., in the distribution of bowlders from the region west of the valley. These bowlders, in general, were dropped in the valley, they sinking in the ice till within the valley flow ; so that, in such a case, they prove only that the flow characterizing the upper ice continued part of the way across the Connecticut valley. Other examples of valley ice-streams are those of the Merrimac, N.H., of the Winooski Valley in Vermont, and that of Lake Champlain, as proved by the glacial scratches observed by C. H. Hitchcock. Transportation and Deposition. 1. Gathering of material, and its condition. The ice-sheet received little material from avalanches, that is, through falls of ice or stones from pre- cipitous declivities or overhanging cliffs, except toward its front margin;, for, in the maximum stage of the ice, it covered all the mountains, except the highest. The moving mass carried debris for the most part, not from the slopes and summits of emerged ridges, but from those underneath it, against or upon which it rested, and chiefly from the slopes and summits of such ridges rather than from level surfaces. It obtained its load by abrad- ing, plowing, crushing, and tearing from these underlying slopes and summits. It took up the loose earth and stones, abraded the hard rocks, plowed into the soft, and broke and tore off small and large bowlders from, the fissured or jointed rocks. The ice-mass was a coarse tool; but through the facility with which it broke and adapted itself to uneven surfaces, it was well fitted for all kinds of shoving, tearing, and abrading work. Moreover, it was a tool urged on by enormous pressure. A thickness of 1000 feet corresponds to at least 50,000 pounds to the square foot. The ice that was forced into the openings and crevices in the rocks had thereby enormous power in breaking down ledges, prying off bowlders, and in abrading and corrading. In contrast, the ice of an Alpine glacier has a thickness ordinarily of but 300 to 500 feet. It gathered little from the lowest parts of the narrower valleys, because of the subglacial stream often present there, and the open space in the ice above it the ice resting itself in such cases mostly against the sides of the valley. Where the fissured rocks were hard, large stones were taken up, some of them hundreds, and occasionally thousands, of tons in weight. But in regions of soft rocks, such as shale, slate, and fragile sandstone, and of rocks easily decomposed, the material obtained was merely sand, earth, or small stones that were readily reduced to earth. Over areas of great extent, therefore, the glacier moved on with little besides the finer debris to dis- tribute. Such facts suggest a reason for the frequent absence of stones and large bowlders from large parts of a glaciated region. In consequence of this subglacial method of gathering materials, nearly all transported debris of the glacier was confined at first to its lower part, <958 HISTORICAL GEOLOGY. within 500 to 1500 feet of the bottom. It was intraglacial, 1 as now in Green- land ; there was in general no superglacial drift over the ice-sheet. The local exceptions to this occur over the melting lower margin ; for a short distance about some "Nunatak" (page 240), where local melting had favored the growth of alpine Algae ; and in regions reached by the dust of the drifting winds. Even the stones and gravel, taken up from the bottom over which the ice moved, might have been carried upward along oblique planes of bedding or lamination into the ice-mass. A paragraph from the chapter on Glaciers (page 246) is here repeated because of its apparent importance in connection with the accumulation, transportation, and deposition of the drift. The slipping of the ice along planes of bedding or straticulation like that of the blue bands has been shown by Forel to be a fact in several glaciers, among them the Bossons Glacier at Chamouni. In the lower part of a glacier these planes have a dip upstream ; and as a consequence, the mass of the glacier, as it moves down the valley, rises by slip- ping along one or more of the planes of lamellar structure. Forel observes that the fact explains the difference of velocity between the upper and lower beds of the ice ; the little movement at the extremity of a glacier; the reappearance, at the surface, of bodies buried in the interior of the glacier ; and the preservation of the thickness of the ice at the lower extremity, notwithstanding the annual loss from melting. The cause must have great influence over the direction of crevasses, and in all adjustments to resistances. He states further that at the Glacier of Hochsbalm, a frontal moraine was formed in 1884, by the slipping of a bed of clean ice over an old bed of debris-covered ice. (Arch. Phys. Nat. Geneve, 1889, xxii., 276, and Am. Jour. Sc., 1889, xxxviii., 412.) Besides taking up material for transportation, the glacier pushed along bowlders and gravel wherever its mass rested, and especially where there was a rocky surface at shallow depth below for it to slip over ; and the loose material gathered, besides serving for abrasion, made a prominent part of the ground-moraine here and there in progress of accumulation. The uneasy glacier stream uneasy because forced to make unceasingly new adjustments to the uneven surface underneath it carried on the work of corrasion among the transported stones with vastly greater force than running water, because the ice had a firm hold on the stones and was plied by pressure of vast amount. It was a wonderfully efficient rock-mill. The stones, hard or soft, had their angles and surfaces rounded, and then were gradually reduced to sand, earth, and rock-flour. Owing to this wearing out of the stones, the drift in any region seldom contained stones gathered from points more remote than the last fifty miles of travel. Shaler states that the stones and bowlders on Nantucket were all gathered by the ice east of Narragansett Bay. It is not surprising that, in Illinois, Indiana, and Iowa, where the distance of travel from any good gathering-place was great, stones in the drift should be few, and be almost confined to the hardest kinds, as those of chert ; that the southern ice-limit should in some parts have no well-defined moraine ; 1 The term englacial, used by some writers, is not here adopted because it is half Greek. Intraglacial accords with Latin usage. CENOZOIC TIME QUATERNARY. 959 that clay makes a part of till, and sometimes interlaminating beds ; and that half-decomposed rock-flour, fitted to make loess, should have been contributed so abundantly to the Mississippi and its tributaries. The smaller traveled stones were sometimes ground smooth on several sides, and thus facetted, so as to resemble human flint implements. Shaler mentions the frequent occurrence of such facetted stones on Nantucket, and W. P. Blake has found many over Mill Rock, near New Haven, Conn. The process of decomposition went forward rapidly because the stones were in a moist place, and the needed air penetrated all glaciers. Moreover, through the carbonic acid present in the ice, as it is present in all rain or snow, decomposition of other kinds went forward, and especially that of changing the finely powdered feldspar to clay (page 129). The microscopic vegetation not uncommon in glacier ice, including that of Greenland, may, through its decay, have afforded additional carbonic acid, and also organic acids for the work of decomposition. There is little of this clay made in the region of the Alps, but it was almost universal when the continental ice flowed over regions where crystal- line rocks were to be had ; and the distribution of clay in great beds over glaciated areas, as well as in the bowlder clay, is thus accounted for. The invading ice in its first movement trod down the forests and carried off the broken trunks ; and some trunks and stumps and eddy-like gatherings of leaves in the till or bowlder clay of Ohio, Indiana, Illinois, and other states west may have thus been gathered. The accumulation of soil and the growth of forests over the debris that accumulates on the melting margin of a glacier, as on the St. Elias glacier (page 239), illustrates a common process of the Ice age. 2. Transportation. In the work of transportation both ice and water were concerned. Melting, through the warmer season, and copious rains sup- plied the water. The glaciers of the Alps and Greenland teach that super- glacial lakes and streams may thus have been made, which contributed water to sub-glacial rivers. The distance of transportation by the glacier varied from 10 miles or less to 500 ; and more examples of distant travel would exist if stones did not wear out. Native copper has the advantage of stone, and some of its masses made a journey of at least 450 miles, as stated on page 952. The direction of travel is sometimes indicated by the occurrence of long trains of stones leading off from the ledge or peak which afforded them. A hill of hard quartzose chloritic rocks on the borders of Lebanon and Canaan, in Rensselaer County, N. Y., was the parent source of the " Eichmond " train of large stones that crosses the Taconic Kange into Massachusetts, and is continued on over Richmond and Lenox into Tyringham (S. Reid, 1842, E. Hitchcock, 1844, E. R. Benton, 1878). Some of the transported bowlders exceed 1000 tons in weight. The "Churchill Rock" at Nottingham, N.H., described by C. H. Hitchcock, is 62, 40, and 40 feet in its diameters, and is estimated to weigh about 6000 tons. 960 HISTORICAL GEOLOGY. The " Green Mountain Giant " at Whitingham, Vt., weighs about 3000 tons;. "W. 0. Crosby has described a bowlder on the eastern border of New Hamp- shire having diameters of 30, 40, and 75 feet, and weighing 6000 tons. In Ohio there is one 16 feet thick, which covers three fourths of an acre. From southwestern Vermont, the granite of a high hill, between Stamford and Pownal, which is almost as high as the Green and Hoosac Mountains lying to the east and south- east, was carried southeastwardly over the western sides of these mountains, nearly across the state of Massachusetts. Iron Hill of Cumberland, R.I., furnished bowlders of iron ore for the country south of Providence, to the Newport region, thirty-five miles distant, and thence south of east, as. shown by Shaler, to Gay Head on Martha's Vineyard. Large bowlders are scattered widely over eastern Long Island, which are the crystal- line rocks, trap, and sandstone of New England ; and others, over western Long Island, which are from the Palisades and heights along the Hudson Kiver. South of Lake Superior, there are bowlders which have come from the north shore of the lake. In this movement of the glacier the transported stones and earth, at first intraglacial, have sometimes become superglacial, about any emerged or nearly emerged mountain peak, as in Greenland about the " Nunataks " (page 249). And after serving as a superglacial moraine for awhile, the whole may have sunk away through crevices or crevasses to intraglacial positions again. The ice, as it moves up a long slope of a hill or mountain-side, slips over the- rising surface, and carries its load with it ; and on many slopes such stones are found at a level 1000 to 3000 feet or more above their source. Mount Katahdin in Maine has many bowlders on its northern face derived from; the Devonian rocks of the low country to the north, 3000 feet below it in level, which were thus carried up the mountain. Stones from a low level! in the ice may thus, if not stranded on the slopes, use the high level for further travel or continue on at their original level. 3. Deposition. The deposition of the transported material took place (1) through crevasses and crevices, aided by descending waters from the- superficial lakes or streams ; (2) from the melting bottom of the glacier ; (3) from the melting always in progress along the front of the glacier,, which was augmented during retreats. Moreover, the material pushed along by the glacier was an important addition to the moraine-making debris set free by the melting ice. Great bowlders would be the first landed from the decaying ice-mass ; yet large and small stones, earth and clay, are so mingled in the till that the term bowlder-day is well applied to the larger part. The stones of the till show their glacier origin usually by marks of abrasion. But flowing glacial waters carrying sand have often worn smooth the glacier- dropped stones and bowlders. The subglacial waters, wherever in gentle flow along their valleys, may have made part of the local deposits of clay and sand, while others were made by the waters flowing away from the front. 4. The terminal moraine or southernmost Ice-limit. The terminal moraine marks the limit of the ice-sheet when it was of maximum extension, and therefore when of maximum power for work, whether at abrasion, corrasion,, CENOZOIC TIME QUATERNARY. 961 or transportation. Along portions of the line in western Pennsylvania, Ohio, and Indiana, the amount of drift material is small, so that it is sometimes called the attenuated margin of the drift. But at some places in Ohio the terminal till is stated by Wright to be 100 feet thick or more. In southern Illinois, Williamson County, the thickness at the limit averages, according to Chamberlin and Leverett, 20 feet, and in some places is 50 feet thick ; and striation is deep in the vicinity, proving the action of a land ice-mass. In Kansas and Missouri, the most southern portion of the drift, there are bowlders of considerable size. To the eastward, in eastern Pennsylvania, near South Bethlehem, the Durham and Eeading Hills, 665 to 900 feet high, have bowlders and scratches at all altitudes. Far eastward, south of New England, in the region of greatest precipi- tation, the terminal moraine extends along the islands from Nantucket, Martha's Vineyard, by Block Island, to the south part of Long Island. On this island, west of the Shinecock Hills, there is a long interval of stratified sands ; and then at the western extremity of the island the drift is again at the surface, and continues to Staten Island and New Jersey. The deposits are coarse, 100 to 200 feet or more in thickness, partly stratified in places, and carry large bowlders. Ten to twenty miles north of the line just described, from Cape Cod along the Elizabeth Islands and the shores of Khode Island and Connecticut, between Narragansett Bay and Watch Hill, and then along Fishers Island and the north side of Long Island, there is a second range of terminal moraine, as first announced by Upham. The islands are not drift made ; for they had an earlier existence, as subjacent Cretaceous and other terranes show ; and they may, therefore, have determined the twofold subdivisions of the drift. Yet it is more probable that there are two lines of moraines, and that only the more southern is to be taken as the terminal moraine, or that at the limit of maximum exten- sion. Nothing is known to exist over the sea bottom south of Long Island to indicate a still more southern line, although the surface for 25 miles or more seaward was part of the dry land. This epoch of the advance in the Glacial period was probably of great length. The vastness of the area covered with ice, the thickness of the ice- mass, and its accumulation even over the dry Continental Interior, lead to this conclusion; and, as has been shown, the attenuation of the drift along much of the front is not evidence against it ; for, notwithstanding this, there was slow transportation to the limit. The terminal moraine, or southernmost limit of the ice, was located along the islands south of New England first by Upharu and Clarence King ; and along the coast east of Watch Hill (which is a continuation of Fishers Island) by C. King. Its location over New Jersey was made out by G. H. Cook and F. Smock. 2. Epoch of the First Retreat. 1. Distance of the Retreat. The evidence of a retreat of the ice-front is afforded by the condition of the till and other glacial deposits over the region of the retreat, and by the record of a long halt at the close in the DANA'S MANUAL 61 962 HISTORICAL GEOLOGY. existence ordinarily, as the northern limit of the retreat, of a more or less prominent belt or line of moraine. The course of this moraine-line, as mapped chiefly by Chamberlin and Leverett, is shown on the map (Fig. 1548) . It is the line lettered B, B, B, and is designated the moraine B, or moraine-line B. The belt of land laid bare by the retreat extended westward to the Continental Interior ; no such retreat has yet been recognized west of the Rocky Mountain region. In Illinois, the moraine B includes the Shelbyville moraine of Chamberlin and Xieverett, which passes near Shelbyville in central Illinois, and probably the Altamont, of Upham, in central Iowa, the southernmost of the series in that state. The width of this belt varies from 10 miles and less to more than 300 miles. It is least along the islands south of New England, and through New Jersey and Pennsylvania, where the precipitation was greatest so great that the annual accumulation of ice fell but little behind the amount lost by melting. But farther west, from western Ohio to the Conti- nental Interior, the width increases with the decrease in the amount of precipitation. In western Ohio and Indiana, the mean width is 40 miles ; from Illinois to northwestern Kansas, it increases from 150 to 275 miles ; and the driftless area, lying chiefly in Wisconsin, is made part of a much larger iceless area. From Kansas in a northwestward direction, the region of melting stretched northwestward over the district of Assiniboia to the Saskatchewan, or 1000 miles, if not beyond this ; and as the dotted line (Fig. 1548) is the limit of transportation of drift from the eastward, and B B that of the morainic limit of the melting (along the Coteau du Missouris and the third Prairie level, in continuation of the Coteau des Prairies, as laid down by G. M. Dawson), the width of the area laid bare in British America is full 300 miles. The district of the Winnipeg region was still under ice. Between Cape Cod and northeastern Kansas the retreat was from the south, northward, but in British America it was from the west, eastward, and east-northeastward ; that is, it was from the borders of the great ice-sheet inward. Along the Coteau des Prairies, the retreat from west to east was small, because the region west of that part of the Missouri was bare through all the epoch of maximum ice owing to drought and heat. South of New England the southernmost line, AA, from Nantucket to Perth Amboy is but a few miles from that of the moraine B situated along the inner range of islands, the coast west of Narragansett Bay, Fishers Island, Peconic Bay, and the north half of Long Island westward. At the head of Peconic Bay the moraines of the north and south sides of the bay blend with one another. It is not certain that the moraine of the southern limit, or that of maximum ice, was not outside of these islands, as it was prob- ably outside the existing shore line to the east of New England, Georges Shoal being probably on or near the limit. The retreat from this eastern limit was probably to some line now under water ; for the moraine on Cape Ann, north of the harbor of Boston, has been shown by Tarr to be part of the east-and-west moraine extending westward to the Connecticut. CENOZOIC TIME QUATERNARY. 963 The nearness of the moraine-line A, or the southern ice-limit, to that of moraine-line B in Pennsylvania may be owing to the fact that the course of each was not dependent on the isotherms, but on the leeward position of the region with reference to the icy heights to the northeastward (page 956). 2. Deposition and distribution of drift. With, the melting and retreat of the ice-sheet, deposition of the transported material went forward making a covering of till of varying thickness, deposits in some parts of clay and rock-flour over and within the till, and intercalated deposits also of soil, sometimes with remains of forests, as has been already described. Besides, the escaping waters carried away material, fine and coarse, for stratified beds of clay, sand, and gravel. The older till over Illinois and Indiana has usu- ally a depth of about 20 feet. In southeastern Indiana and southwestern Ohio, according to Leverett, it was followed by a covering of soil and then a deposit of clay to a depth of several feet; and as the clay contains, according to an analysis, 2-32 per cent of potash and soda, 16 per cent of it or more is feldspar in grains. The beds of soil and the forest-beds in glacial deposits are mostly contained in those that were made during this retreat. 1550. Upper part of Moraine, Dogtown Commons, Cape Ann. Shaler, 1889. The moraine ridge, which marks the limit of the retreat, consisting chiefly of gravel, stones, and bowlders, was made by the deposition, along the front, of material brought down by the ice-sheet during a long halt. It indicates the transporting power of the ice ; and as the moraine in Illinois and Iowa is over 150 miles north of the southern ice-limit, the surface of the ice-sheet may have had a steeper pitch than during the period of maximum ice, so that transportation went on more rapidly, while corrasion and deposition were less effective agencies of rock-wear. The halt had, as usual, its advances and 964 HISTORICAL GEOLOGY. recessions ; and this was one means by which the moraine ridge was widened and rendered irregular in height and surface. The foregoing figure of part of a moraine on Cape Ann, Mass., from a paper by Shaler, though belonging to a later part of the Glacial history, shows the common appearance of such moraines at the present time. A great feature of the epoch was the amount of water discharged, making new channels by erosion and giving the streams in the region of melting great transporting and eroding powers. The Delaware, Susque- hanna, Ohio, and other streams were flooded; and the Mississippi derived waters not only from the Ohio with its many tributaries and from the icy heights of the Rocky Mountains, but also through the Missouri from British America, far north of Montana, perhaps from the upper portion of the Saskatchewan. Distribution of the transported material supplied by the melting ice, and erosion by the loaded waters went forward, therefore,, with unwonted energy. With the continent at its high level, the flooded rivers over all the conti- nent dug out their channels, during the time of maximum ice, often to great depths ; then at the melting the channels were filled with till, and, over the-, till, with fluvial beds of sand or gravel. The Mississippi valley received then its earlier deposits of loess, over lake-like regions along its course, while- other portions of the valley had their coarser deposits. South of New England, the retreat was short. On Long Island, then probably 500 feet high, the eroding waters carried off seaward the terminal moraine of the south shore for 70 miles of its length, and dropped till over the denuded surface ; then later waters covered it with sand and fine gravel ; for there are no bowlders or till to be seen over the even slopes, although abundant elsewhere on the island. So also the waters that descended the north slopes of the island from the moraine belt, cut out of the morainic accumulations, and underlying Cretaceous formation a number of short, steep valleys, and left them similarly under fluvial sand-beds as the top-dressing, with no bowlders over their surface ; ; and the valleys, after the Champlain subsidence which restored the waters of the Sound to their place became the deep and capacious harbors of the north coast. During the epoch when the Mississippi was receiving waters, by the- Missouri, from the melting in progress through a thousand miles from south to north, with other floods from the ice and snows to the east and the glacier regions in the Eocky Mountains, the deposition took place, of what has been named the Lafayette formation the Orange sand formation of Hilgard. As shown by Hilgard, the Lafayette was a widespread flood- made formation, extending along the great valley of the continent, the Mississippi, south of its junction with the Missouri, from southern Illinois to the Gulf. Its eastern border passes near Cairo through western Kentucky and Tennessee, and the northeast corner of the Mississippi, and, according to L. Johnson, reaches the shore of Mobile Bay in Alabama. Its western border crosses Arkansas and Louisiana into Texas. The formation is described as consisting mostly of rust-colored or reddish siliceous sand-beds. Near the great river channels, notably that of the CENOZOIC TIME QUATERNARY. 965 Mississippi on either side, of the Tombigbee and Tennessee, as well as of the Sabine, there is a steady increase of gravel. It occasionally contains, even in Mississippi, stones of 10 to 100 pounds in weight, and rarely 150 pounds. There are also some local clayey beds. The stones show that the material came from the northward; many have in them Paleozoic fossils. The beds are irregularly stratified, sometimes structureless for 20 feet of thickness, but have generally the Jlow-and-plunge structure, illustrated in Fig. 63, page 93. The facts prove, as Hilgard states, that there was a vast and violent flow of waters down the broad Mississippi valley, bearing an immense amount of sand and coarser detritus, and also some floating ice for the transportation of the larger stones. Hilgard therefore concluded that it muse have been made during the melting of the ice, while the conti-. nent had still the elevation characterizing the Glacial period. These condi- tions are those of the First Retreat. There were cotemporaneous depositions from streams descending the Atlantic and southern slopes of the then snow-clad Appalachians ; and large areas of the Lafayette formation in these regions and elsewhere have been defined and mapped by McGee. The "Orange sand " is often 40' to 100' thick, and in some places over 200' according to Hilgard, and toward the Gulf it has still greater thickness. In an Artesian well, near the Calcasieu River, 200 miles west of New Orleans, beds referred to the Lafayette are 450' thick, beneath 160' of clay of the Port Hudson group ; and at New Orleans 760'. This thickness along the Gulf is supposed to be evidence of a gradual subsidence of its bor- der to the great depth stated, as deposition went forward. The actual limit of the formation is in doubt because it contains no fossils, and the criterion usually appealed to in its correlation, kinds and color of gravels, is admitted to have, whatever the rock series, almost no value. In Texas, some beds referred to the Lafayette were found by G. D. Harris to contain Tertiary fossils. In his early account of the formation, Hilgard stated, on the authority of Tuomey and LeConte, that the formation passed from Alabama eastward, around the higher Appa- lachian highlands into the Carolinas, and thence north to Virginia and Maryland. McGee described, in 1888, similar beds of orange-colored sands and clays along the Appomattox River and other points in Virginia, and also others, in North Carolina and beyond, to which he gave the name of the Appomattox formation, and he has since studied the beds in the Mississippi valley. He argues that part of the borders of the Atlantic and Mexican Gulf were 200' to 800' below their present level at the time, making the beds in part marine. No marine fossils or other marine relics have been described in evidence of the submergence. Moreover the formation is made preglacial by McGee, and others. The term Lafayette was substituted in 1892, by agreement, for the older names of Orange sand and Appomattox. Mr. Hilgard's last paper on the subject is in the Am. Jour. Sc., xliii., 1892 ; and Mr. McGee's first on the Appomattox in Am. Jour. Sc., xxxv., 1888, and his last on the Lafayette formation in vol. xii., Eep. U. S. Geol. Surv., 1892. 3. River channels filled by the drift. The discharge of drift from the melting glacier sometimes filled up and blocked river channels at places, and compelled the river to make a new cut. The Ohio Elver, according to Newberry, formerly had a more southern 966 HISTORICAL GEOLOGY. route around the Falls near Louisville, which it lost when the ice extended to its southernmost limit. The Falls are evidence of uncompleted work in subsequent erosion along the valley. It is held by some investigators of the drift, and prominently by Chamberlin, that the retreat, instead of ending along the line of the moraine above described, continued until North America had lost the chief part of its ice-sheet, and that this " First Glacial Epoch ' r was followed by a second advance, of which moraine B was the terminal moraine. This view is sustained on the ground that the erosion produced during the interval, the inter- calation of forest-beds and stratified clays, and the weathering and oxidation of the lower tills would have required a very long period of time. It is, however, an important consideration in favor of the shorter retreat, that the beds eroded were, to a great extent,, soft ; that the amount of water discharged was very large ; and that interstratified sand- ' beds and forest-beds are such as modern glaciers are now producing. The arguments and facts favoring the theory of two glacial epochs and an interglacial are presented by Cham- berlin in his Report on the Geology of Wisconsin ; also in the 3d and 7th Reports of the U. S. Geol. Surv., and in later publications, in part of which Leverett is joint author ; by G. M. Dawson in his Memoir on Rocky Mountain Geology in the Trans. Hoy. Soc. Canada, vol. viii., 1890, etc. Upham, Hitchcock, Wright, and others favor the idea of a continuous succession of recessions and halts during the retreat. In northeastern Iowa, according to McGee, the successive glacial deposits are : (1) the lower till, which is overlaid by stratified sands and clays (called locally gumbo) ; (2) a. forest-bed, with unconformity beneath through erosion and decomposition ; (3) an upper till of small extent, from ice that was of short duration ; (4) the loess, which contains some bowlders, and graduates at base into the till. These are supposed to be anterior to- what is called by Chamberlin the Second Glacial Epoch. The loess is stated to have been formed in an ice-bound lake, which he names Lake Hennepin, made by the meeting of two lobes of ice, advancing either side of the Driftless area. The loess makes a fertile soil, which appears to be evidence that there was abundant vegetation in the waters in which it was deposited, and thus throws doubt over the presence of the ice. The depau- perate condition of the shells shows only that the waters were cold ; and their great numbers, that conditions of growth were still not very unfavorable. The great distance of transportation of glacial drift over the Continental Interior in British America, and the remarkable uniformity in the drift deposits over the vast area u 250,000 square miles " has led to the view that the region was submerged under fresh or salt waters, and that floating ice was the transporter. But the flow over such waters, whether tidal or not, would have been north and south, and not across the area ; and there is no evidence of marine conditions. Moreover, if floating ice worked there, it waa the agent to the south in the United States ; and this is not in accordance with the facts there observed. Land and freshwater shells and other fossils of the loess of the Mississippi valley. From Galena, 111. : Succinea avara, S. obliqua, Patula striatella ; Vallonia pulchella, Limnophysa humilis, L. desidiosa, Pupa contracta, P. muscorum (R. E. Call). From Davenport, la. : Succinea avara, S. obliqua, Helicina occulta, Pupa fallax, Helix stria- tella. Also tusk and molars of Elephas primigenius (Pratt). From Muscatine, la.: Helix striatella, H. fulva, H. pulchella, H. lineata, H. Cuperi, Pupa Blandi, P. quarti- caria, P. muscorum, P. simplex, Succinea avara, S. obliqua, Helicina occulta, Limncea humilis, Unio ebenus, U. ligamentinus, U. rectus, Melantho subsolida, Harcjaritina con- fragosa. Also teeth, bones, and antlers of Cervus Muscatinensis (Witter, in McGee's Iowa}. From Hickman, in Kentucky : Conulus chersina, Hyalina arborea, Helicina orbicu- lata, H. profunda, Limncea (Limnophysa) desidiosa, Mesodon profundus, M. albolabris, Macrocyclis concava, Patula alternata, P. perspectiva, P. solitaria, Stenotrema (Helix) GENOZOIC TIME QUATERNARY. 907 monodon, S. hirsutum, Treodopsis appressa (Wetherby). The species are all of kinds now living in the vicinity of the several localities. The shells of the Iowa lake are much below the natural size of the species, showing the depauperating effect of the cold water (McGee) ; but in Kentucky those obtained near the Mississippi are larger than those a few miles to the eastward (Loughridge). 3. Epoch of the Final Retreat. At the commencement of the Final Retreat, as shown by the position of moraine B, ice still covered all New England, all ^Ne\v York, and very nearly all that part of Pennsylvania that was covered at the time of maxi- mum ice. Bnt in Illinois and farther west to Dakota, the First Retreat had left bare a broad belt, which extended northwestward into British America west of Manitoba. In the Final Retreat the Mississippi valley was still, compared with the east, the region of most rapid melting, and for the same reason as before the warmer and drier climate. The series of loop-shaped moraines in Illi- nois and Wisconsin, and that in Iowa and Minnesota, mark the succession of halts and recessions in the course of the retreat northward from the moraine line B. The Illinois series, as described by Chamberlin and Leverett, covers much of Illinois and passes thence into Wisconsin ; and the Iowa-Minnesota series, as mapped by Upham, extends first northward and then over Minne- sota northeastward, for more than 400 miles. In addition, the retreat was going on from the moraine line B in Assiniboia, north of Montana, laying bare much of Manitoba. In the Illinois series of moraines, there is near Madison the noted Kettle moraine (KK on the map), more than 200 miles from the line B, or that of the Shelbyville moraine. But in Indiana the distance of retreat between the moraine line B and the line K, or that of the Kettle moraine, narrows rapidly ; and in Ohio it is very small, the first moraine north of the moraine B being regarded by Chamberlin and Leverett as probably the moraine K. Farther east, moraine K extends along with moraine B into western New York. It has been supposed by Chamberlin to pass probably south of Cayuga and the other Finger Lakes. In view of the nearness to the line B in Ohio, it may be questioned whether it does not take the same oblique course with it through Pennsylvania and become there indistinguishable from it ; and the same also farther eastward across New Jersey and south of New England. If this is the right view, New England held to its ice during all the retreat in Illinois of 200 miles, precipitation to the eastward adding about as much ice as was lost by the melting. Subsequently the final retreat involved the Eastern States as well as the Mississippi valley, and moraines over New England and New York mark its progress. One, as described by R. S. Tarr, crosses Massachusetts west of the Connecticut, passing south of Turner's Falls, Orange, Royalston, Win- chendon, and terminates in the Cape Ann moraine described by Shaler. $38 HISTORICAL GEOLOGY. Three or four others, according to C. H. Hitchcock, exist in Vermont and New Hampshire. The moraines made on this final retreat bring to light the fact, as observed by Chamberlin, that the movements of the ice-sheet in the region of the Great Lakes became largely resolved into movements along lake- basins. They thus bear testimony to the preglacial existence of the basins of the Great Lakes. The Kettle moraine (KK) is concentric with the out- line of the Green Bay trough, a western arm of Lake Michigan ; a Michigan moraine borders the Lake Michigan basin ; and a series of Erie moraines, as mapped by Leverett, are approximately parallel with the western part of the Lake Erie basin. Besides, there are indications of a Saginaw glacier movement, along the trough of Saginaw Bay on the west side of Lake Huron, as an outlet for the ice of the Lake Huron basin. There were thus brought to view more or less distinctly, as melting went forward, the outline of a Green Bay, Michigan, Saginaw or Huron and Erie glacier. Lake Ontario and Lake Erie, during the time of maximum ice and long after retreat began, were crossed by the ice in a southward direction, the glacial scratches south of Ontario having the direction S. 8-20 E., and those south of Erie mostly S. 20-30 E. But the evidence of a lake-basin movement really an Erie-Ontario movement is sustained by scratches at the east end of Ontario, and over the region at the west end of Erie. In the latter region, the deep moldings in the limestone of Kelley Island have the courses S. 60-80 W. (Newberry) ; and west of the lake the same direc- tions prevail. This westward flow in the Erie basin, first pointed out by Gilbert, and later sustained by Chamberlin and Leverett, must have been dependent in part 011 a like movement in Lake Ontario, for the supply of ice required a general westward slope in the ice-surface to the eastward; and the Adirondack ice-region was its probable source. Chamberlin and Leverett also bring forward evidence from the moraines (see map, Fig. 1548) that Lake Erie was rid of its ice before the more northern Lake Ontario. The movement along the troughs of Lake Michigan and Green Bay, sug- gested by the moraines, as Chamberlin points out, proves, if a fact, that the ice over the troughs had the slope at surface requisite for movement and transportation. The length of Lake Michigan is 335 miles ; and hence, if the mean slope was but 30 feet per mile, the height of the ice-surface at the north end, above that at the south, would have been 10,000 feet ; and two thirds of this if the rate were but 20 feet per mile. With such evidence of a southward movement there is no satisfactory proof that a subsidence was in progress to the north, although the retreat of the ice had even reached the Canadian borders. The Iowa-Minnesota series of moraines appears to indicate a like move- ment, and a like northeastward rise in the slope of the ice-surface. With the retreat of the ice from Minnesota, the ice disappeared from much of the more northern Lake Winnipeg region ; and Lake Winnipeg, receiving waters from melting ice on its eastern and northern borders, as well as from CENOZOIC TIME QUATERNARY. 969 rivers to the west, then began, while the continent over this interior region, was still at high elevation, its discharge by the Red Eiver of the North into the Minnesota, and the Mississippi became emphatically the " Great Mississippi." It was at this time of the departure of the ice from the lake region to the country north of Lake Superior, before a subsidence had made much if any progress, that the areas of the Great Lakes were fluvial areas, carrying on vigorously the work of excavation under the high southward slopes due to more northern elevation ; that Michigan was discharging its abundant waters through the Illinois or the Kankakee channel to the Mississippi; Erie, with probably Huron, through the Wabash, to the Ohio ; and Superior, through the Fox or Wisconsin, to the Mississippi. The waters of Ontario are supposed to have gone eastward to the valley of the Mohawk, but for want of satisfactory evidence as to any other course. The following are the views of Chamberlin and Leverett, with regard to the stages in the interval between the time of maximum extension and that of the Kettle moraine : (1) Partial deglaciation, and the formation of a sheet of drift perhaps 20' in thickness, with occasional layers of soil interbedded in the drift. (2) Interval of deglaciation of great length, the surface of old drift sheet deeply oxidized, leached, much eroded, with thick widespread soil above. (3) Deposition of main body of loess and associated silts along the Mississippi, Illinois, Wabash, and Ohio rivers, and between the Illinois and Mississippi, and the material in southern Indiana and southwestern Ohio called "White Clay." (4) Long interval of deglaciation, and deep erosion, cutting large valleys in the loess. (5) Formation of a thick sheet of drift terminated by the Shelbyville moraine, 75' to 100' deep, the maximum advance of the ice after the long deglaciation having termi- nated at or near the line of this moraine ; and, following the deposition of the Shelbyville moraine, other moraines in succession at short intervals up to the Kettle moraine series. (6) An interval during which ice-lobes and ice-currents were shifted. (7) Moraines of the Kettle moraine series of Illinois and Wisconsin. In remarks on these stages, it is stated that as far as the correlation of the Kettle moraine has been made out, the Shelby- ville series of moraines is represented in western Ohio by only a single moraine, and in eastern Ohio and northwestern Pennsylvania, it is nowhere in view, and is supposed to be concealed by the Kettle moraine series. The correlate line across western Indiana of the Kettle moraine is difficult to make out. In eastern Ohio the outer belt from the Scioto River to southwestern New York has knobs and basins like the Kettle moraine ; and the moraine south of the Finger Lakes (Cayuga, Seneca, and others) is made the probable con- tinuation of the Kettle moraine series. The overwash from the Lake Michigan and Erie moraines over Saginaw moraine in northern Indiana seems to show that the ice had withdrawn from the Saginaw moraine while it was forming the series west of Lake Erie. With regard to the conclusions of Chamberlin and also of Leverett here and elsewhere cited, they say that their observations are still in progress, and their state- ments are not to be taken as final. Upham names as follows the Iowa-Minnesota moraines, commencing at the south : 1, the Altamont ; 2, the Gary ; 3, the Antelope ; 4, the Keister ; 5, the Elysian ; 6, the Waconia ; 7, the Dovre ; 8, the Fergus Falls ; 9, the Leaf Hills ; 10, the Itasca ; 11, the Mesabi ; 12, the Vermilion (Final Rep. Geol. Minn., vols. i., ii., and 22d Ann. Rep.). Lateral moraines are seldom well marked over any part of glaciated North America, because the mountains, with rare exceptions, were beneath the ice-sheet; and there were no true valley glaciers, except occasionally 970 HISTORICAL GEOLOGY. along the front. But in some large submerged valleys, like that of the Connecticut, in which the bottom ice had a movement of flow in the direc- tion of the valley, there were sometimes obstructing conditions which pro- duced a forced deposition of bowlders and till, and thus made an accumulation somewhat moraine-like, which might be called an obstruction moraine. A good example exists along the west side of the south end of the Connecticut valley, in the vicinity of New Haven. This declivity is rather abrupt, and has a nearly north- and-south direction, while the course of the valley ice-stream, as described on page 956, was S. 15 W. The ice-stream, in meeting the obstructing ridge or declivity, dropped along, it a large amount of till and many great bowlders of trap and sandstone. The top of the ridge, five miles from the Sound, is about 300' above the lower land to the east, and 400' above the sea level. One great bowlder of 1200 tons, and several others of large size near by, were a little too low in the ice to pass the top of the ridge, and consequently became stranded against its slopes, or combed out by its summit ledges. Half a mile north is another trap bowlder of 500 tons, and several exceeding 100 tons lie to the south. A mile and a half to the east, but separated by an open valley 300' deep, stands the West Rock trap ridge, of equal height ; and on this ridge, and almost in an east and west line with the 1200-ton bowlder iust mentioned, at a like height, there is a 1000-ton bowlder, which was similarly stranded. For a distance of 10 miles from Long Island Sound the great bowlders are common, and the till against the slopes has unusual thickness. The upper part of the glacier above the level of the ridges kept on its southeastward course (S. 30-40 E.), carrying bowlders of gneiss from the northwest. But some, if not all, of these gneiss bowlders, while on their way over the valley, dropped down so as to come within the lower or valley ice-movement ; and they are now, as a consequence, part of the obstruction moraine along the eastern base of the West Rock Ridge, and other north- and-south trap ridges of the valley. Among the formations produced by the melting, besides moraines and deposits of till, clay, and other ordinary materials, there were glacial accumu- lations of loose materials called drumlins, and eskers or Jcames, formations that were much less common in connection with the early partial retreat, than with the final. Kettle-holes, also, were a feature of many moraines, from the Coteau des Prairies to Cape Cod. Kettle-holes are bowl-shaped depressions, usually 30 to 50 feet deep and 100 to 500 feet in larger diameter. Each depression, according to the accepted explanation, was the resting-place, and often the burial-place, of a huge mass of ice that became detached during the melting ; and the final melting away of the ice left a hole where the ice lay. The great Wisconsin moraine about Green Bay is called by Chamberlin the "Kettle Range," from the great numbers of its kettle-holes. Near Wood's Hole, in southeastern Massachu- setts, opposite Martha's Vineyard, 1000 kettle-holes occur, according to B. F. Koons, in a distance of about 12 miles. Kettle-holes occur sparingly over Long Island ; but it is possible, since there is clay beneath the drift, that the weight of the overlying drift, with the addition of the resting glacier in some cases, forced aside the clay, flexing its layers in the process, and thus made the bowl-like depressions. Drumlins are hills or ridges of till, 30 to 200 feet high, made ordinarily by deposition from the glacier, or in the course of its dissolution ; and CENOZOIC TIME QUATERNARY. 971 eskers or frames are rougher ridges and hills of rudely stratified coarse and fine gravel, produced by the discharged waters. Drumlins occur in great numbers over New England, especially in Massachusetts and its more northern states, and also in New York and the states west to Dakota. Eighteen hundred drumlins have been observed in Massachusetts alone, and thousands are reported from Wisconsin and the adjoining states. Eskers are widely distributed over Maine, and are common in other parts, of New England and in most regions of the melting ice. Drumlins are commonly more or less oblong, smooth-featured hills, having the longer diameter in the direction of the movement of the glacier. In allusion to their form, they were called "lenticular hills" by E. Hitchcock, their first describer (1842). Such hills may be shaped by fluvial action from beds of till. But drumlins are generally results of local deposition. Their height indicates a source elevated above the general level. Such a source is afforded by the drift in the lower 200 feet or more of the ice. They were probably formed, therefore, under the ice-sheet, and not far from its melting margin.. To gather and pile up the drift within the ice would require the descent of water along crevasses, the water acting by melting, eroding, and transporting. If the crevasse had a direction toward the front, the slow movement of the ice would bring forward new mate- rial for the enlargement and elongation of the hill. A large trench is sometimes made about a dramlin to carry off the copiously descending waters. Crevasses are often due to obstructing rocky ledges or hills below, or to bends in a valley-like depression ; and being thus local in origin, the same spot may be long accu- mulating deposits. Drumlins sometimes have a nucleal mass of stratified gravel and sand containing occasionally intercalated till; and those of Madison, Wis., have the till confined to an outer shell, 20' or 30' thick. Upham, who has described such drumlins, attributes the nucleal stratified portion to moraine materials over the melting margin of the ice carried down by the superglacial waters ; and the till to the final wasting of the glacier, or its removal by the descending waters. They sometimes show their subglacial origin by being crossed by small valleys or trenches of erosion (G. H. Barton). A druinlin of nearly circular outline, on the west side of the valley at New Haven, Conn., height 115', stands on the summit of a rocky ridge, its base being nearly 200' above the sea level. The valley is the south end of the Connecticut valley near where it passes into the trough of Long Island Sound. The lower part of the ice lying in the valley was moving S. 15 W. But, on reaching the trough of the Sound, it was forced to bend abruptly around to S. 20-35 E. in order to take the course of the general glacier move- ment along the Sound. This high isolated drumlin and lower accumulations along the coast westward are evidence of the wrenching and crevassing at the turning spot. This drumlin has, for half of its circuit, a deep valley, made by the deluge of waters that descended the crevasse. Eskers or Kames, unlike the drumlins, are rudely stratified accumulations of gravel, sand, and waterworn stones. They are of rough fluvial or torrential origin, and occur in long tortuous ridges (serpent-kames), mounds, and hummocks. They have the general direction of the drainage, though sometimes not according with the present course of drainage. They occur usually over the lower lands, outside of the steep mountains where the slopes are not large ; yet they are sometimes met with at high elevations. Indian Ridge, near Andover, Mass., was the first of them described (1842, by E. Hitch- cock). Several modes of origin have been suggested. Their formation has generally taken place after melting had made great progress over regions favorable to torrential flows ; where water, coarse gravel, and sand were freely discharged from the broken and '972 HISTORICAL GEOLOGY. melting ice-sheet and sometimes flowed along channels among the ice-masses or in its opened chasms. They were formed also by the gushing streams from the end of glaciers while the ice was rapidly disappearing, and sometimes beneath the ice. They often accompany moraines as an attendant effect. Stone refers those of Maine chiefly to superglacial streams ; and J. B. Woodworth, those of southern New England mainly to subglacial waters, the ice giving them their limits. Deposition seems to have some- times taken place in Maine over frozen soil and lakes, so that when the ice of the lake melted (as in the case of the Rangely Lakes) the kame over it dropped to the bottom. Some of the so-called kames are ordinary fluvial deposits. Kames were so named in Scotland. The EsTcers of Ireland and Osars of Sweden are of like nature. The till along seacoasts sometimes contains marine shells that had been gathered and transported by the glacier. Examples occur in the vicinity of Boston Harbor, especially to the southeast of it, and have been described by Upham (1888), and by W. O. Crosby and Miss Ballard, who enumerate 55 species collected chiefly from drumlins (1894). Simi- lar localities, described by R. Chalmers (1893), exist on the coast of the Bay of Fundy. The till over Ohio has a mean depth, according to measurements in borings made over 53 counties, collated by Orton, exceeding 93 feet, and four borings in Butler County, in the southeast corner of the state, gave 116 feet for the mean depth. The deeper places were along valleys. Excluding valley deposits, the depth is probably nearer 56 feet, as measured by Claypole. In Indiana and Illinois, the mean depth, according to Clay- pole, is 62 feet ; for Central Minnesota, according to Upham, between 100 and 200 feet. Near Darrtown, Butler County, Ohio, there are cedar logs in the till, which, Wright says, point to short times of advance and recession of the ice-front. The Erie days, so named by Logan because forming extensive deposits along Lake Erie, are one of the results of deposition. According to an analysis by T. G. Wormley, the clay contains 3*40 per cent of alkalies, which indicates a mixture of clay with over 20 per cent of ground feldspar. They overlie the till, are unstratified for the most part, and often contain small scattered striated bowlders. The deposit was probably made by sub- glacial streams after their escape from the ice, and by discharged waters during the general melting. Over the Erie clays, near Cleveland, Ohio, there is a stratum of sand, gravel, and clay, and between the two occurs a bed of vegetable debris, one to two feet thick, which Newberry called a forest- bed. It contains portions of tree trunks of Conifers and other vegetable materials. It may belong to the Champlain period. In the Rocky Mountain region of British America and over the Interior Plateau to the west, as G. M. Dawson states, the later till is covered by a deposit called by him the *' White silts," a well-stratified formation which is, at times, in terraces 100' to 200' high. Sometimes it passes gradually into sand-beds. It is supposed by him to have been formed in the valleys of those high regions before the ice had fully disappeared from them. The obstruction of river valleys at points by the discharged till was of common occurrence during the Final Eetreat. A noted case is that of Niagara River, where the river channel, then shallow, was thus filled and the stream forced to begin again the work of excavation. CENOZOIC TIME QUATERNARY. 973 The accompanying birdseye view (Fig. 1551), from a paper by Gilbert,, shows the river between Lake Erie to the south and the land below the- Queenston Heights (Q H). To the right is seen the course of the old now drift-filled channel, first recognized by Lyell. The work of excavation is. still going on, and chiefly at Niagara Falls. The Mississippi River was similarly blocked near its junction with the Minnesota for a distance of about 10 miles, as described by N. H. Winchell. In the new valley, since made by the Mississippi, St. Anthony's Falls occur. The river is still working at the removal of the falls so as to make the cut complete. 1551. Birdseye view of the Niagara Gorge. W, Whirlpool ; Q, Queenston ; Q H, Queenston Heights ; O (Jh, olage 392, a legitimate effect of lateral pressure in the contracting crust ; and the coral-island subsidence, or, in more general language, the deepening of great areas over the oceanic basin, is set forth on the same page as the counterpart. Why, in the upward movement, the colder latitudes, or those outside of the parallel of 40, should have been most affected, as the distribution of fiords and other facts make evident, is wholly unexplained. The interest of the problem is greatly enhanced by the new facts proving that the Ant- arctic Continent also was elevated and greatly enlarged, probably to four times its present area; that not only the lands of the high northern lati- tudes were affected, but also their antipodes in the high southern latitudes. Under these conditions the earth's polar diameter would have received a considerable increase of length, and the waters would have been deepened over the lower latitudes. The idea of Croll, that the Glacial periods of the northern and southern hemispheres followed one another, has no support from geological facts, and few supporters among geologists. The Champlain subsidence following the elevation has been attributed, on the principle of isostasy, as stated on page 379, to the weight of the load of ice over the glaciated land. The cause is good in principle, but of doubtful sufficiency. The facts stated on page 980, with regard to the departure of the ice from the United States before the subsidence had made much progress, indicate a great lagging in the effect, far greater than is com- patible with the results of a load. Moreover, the coast region of California .subsided deeply (page 985) although it had not been covered by ice; and the land which joined South America with Cuba and probably Florida, and that uniting Africa to Malta and Sicily disappeared, although far outside of the ice-limit. The dry land across the British Channel between England .and France continued emerged long after the mild climate, which favored migration of warm climate Mammals, set in; and it became submerged although the land either side was never under the ice-sheet. France and CENOZOIC TIME QUATERNARY. 1021 other parts of Europe bear evidence of subsidence in the many terraced river valleys and sea borders, although never glaciated. Other facts bear- ing on the question will be found in a recent paper by Prestwich on the late Post-glacial submergence. The ice of the locally glaciated areas over Europe could have depressed isostatically only equal areas to a depth less than two fifths of the mean thickness of the ice. The insufficiency of the ice-sheet to produce the widely extended Cham- plain submergence is evident. The only other . agency to which appeal has been made is that of the earth's contraction; this makes the movements of the Quaternary one in cause and system. The Recent period has its epeirogenic movements partly as a continuation of the earlier, and partly as a result, it is believed, of the deposition along coasts and elsewhere of river sediment. The principal facts have been reviewed on pages 341, 367. Another example, of a geanticlinal character, is afforded by the Scandinavian region. A recent report on the subject has been made by L. Holmstrom (1888). On the west coast, at two localities, in latitudes 57 53' K and 58 56' N., the rate of rise of the land, during respectively 66 and 116 years before 1886, was about two inches in ten years ; and at another place, in 58 35' N., about four inches in ten years. On the east coast, at several localities between 58 45' N. and 65 15' N., the rate during various intervals from 45 to 139 years before 1867 to 1875, was 1-8 to four inches in ten years; at Stockholm, 1-85 inches; and in Finland, in 63 N., 2-5 to 3'75 inches. The rise is least to the south. The conclusions differ but little from those derived by Lyell from the facts he gathered, during his visit to the coast in 1834. Moreover, the many fault planes in the earth's crust resulting from old erogenic movements are planes of weakness, and show it from time to time by slips and consequent earthquakes (p:ige 373). It is rendered probable that regions over the Rocky Mountains may still be in slow movement up or down. Upturned beds occur on all the islands south of New England from Long Island to Nantucket. But although the disturbance has been supposed to be of Quaternary origin, the chief part is of earlier date. The beds of Long Island were first described by W. W. Mather in his excellent account of Long Island geology contained in his New York Geo- logical Report (in quarto) of 1843. The deposits, as made by Mather and as has since been proved by fossils, are Creta- ceous clays, sand and pebble beds with overlying Quaternary drift. The bluffs of 150 to 200 feet along the northern coast have the beds mostly concealed by the fallen debris from above. But part of Mather's investigations -were made after a "storm of the llth and 12th of October, 1836," when the cliffs were laid bare, giving him an unusual oppor- tunity for the study of the stratification. He was led to the conclusion that the flexures are partly local displacements in the clay-beds, due to vertical pressure and slides, and partly a result of upturnings anterior to the drift deposits. This accords with the author's observations over the island. It sets aside the idea that the flexures were in any case an effect of pressure from the moving ice-sheet. Figs. 1572 to 1575 are from Plate iv. in Mather's Report. The cramplings in Figs. 1572 and 1573 are like those that are made by local pressure or slides, or sinkings of the 1022 HISTORICAL GEOLOGY. overlying beds, which shoved aside and forced out the wet and mobile clay. At many places along the coast the clay has been forced out in this way and now covers more or less of the slope below ; and in the clay -pits, sinking and exclusions are not uncommon. At the Holmes clay-pit on Fresh Pond, near Northport, there were cracks in 1875 at the top of the bluff where the sinking was in progress, and where, as the proprietor stated, it had amounted to 16 inches in 20 months, and the movement, he added, was all the time going on. A clay -bed is made to vary greatly in thickness in the face of a bluff because locally squeezed out. 1572 1572-1575. 1573 15T4 Sections of the Cretaceous and overlying beds on the north side of Long Island. Figs. 1572, 1573, Sections near Brown's Point, Petty's Bight ; 1574, Section 3 miles south of Oyster Point ; 1575, Section exposed by a storm 200 yards south of Brown's Point. W. W. Mather. In the case represented by Fig. 1575, the position of the beds plainly proves, as Mather states (page 249) , that an upturning and a subsequent denudation had taken place after the lower beds of alternating clay and sand had been formed, and before the deposition of the overlying clay-bed and the higher deposit of "coarse materials and bowlders" or drift. The tilting in Figs. 1572-1574 probably had the same origin. The age of the clay- bed C. I. in Fig. 1575 is left uncertain ; but the upturned beds are Cretaceous. Mather states that in all sections the overlying drift deposits have the same horizontal position, and that some of the bowlders contained in them have great size. "Blocks of 50 to 500 tons are not uncommon on the island" (page 174); and he reports one having an esti- mated weight of 2000 tons. The upturned beds in Desor's Nantucket section, referred to on page 983, are covered by others in horizontal position, and are probably of the same age and origin with those of Long Island. On Martha's Vineyard, according to Shaler, the upturned beds, which include the Cretaceous and Tertiary, bear evidence in their erosion that the chief upturning preceded the Later Glacial epoch, if not partly at least the earlier. Lyell, in his Travels in North America (1845), describes the sections at Gay Head and Chilmark, figures the former (i, 204), and states that the upturning occurred between the Miocene Tertiary and the " Boulder " or Drift period. There is grandeur in the simplicity as well as vastness of the movements by which the earth was made ready for its latest stage. Equally simple and GENERAL OBSERVATIONS. 1023 comprehensive were the agencies set to work : glaciers that reached across from ocean to ocean ; rivers deriving magnitude and energy from the loftiest of mountains, the greatest of ice-sheets and the most abundant of rains; and a genial climate that reached almost to polar latitudes, and produced luxuriant growth in all life, animal as well as vegetable. Thus were evolved, as never before, the sublimity of the mountain peaks, and the richness and varied beauty of the valleys and wide-reaching plains, and the many other surface details that were essential to the pastoral and agricultural pursuits with which man was to commence his own development. GENERAL OBSERVATIONS ON GEOLOGICAL HISTORY. LENGTH OF GEOLOGICAL TIME. Time-ratios. In the preceding edition of this work estimates are given of the relative lengths of the ages and periods, or their time-ratios, based on the maximum thicknesses of the rock formations of the several periods, allowing a ratio of 1 to 5 between the rate for limestone and that for ordi- nary fragmental rocks. These thicknesses have since been increased much for some parts of the geological column ; but the increase is not far from proportional to the former numbers. The evidence at present obtained ap- pears to favor the conclusion that the relative duration of the Cambrian and Silurian, the Devonian and the Carboniferous eras, corresponds to the ratio 41 : 1 : 1, or perhaps 4:1:1, the ratio hitherto adopted ; and for the Paleo- zoic, Mesozoic, and Cenozoic, 12 : 3 : 1. The thickness of upturned rocks is so difficult to obtain with accuracy, and is so certainly exaggerated greatly when the absence of faults and flexures is not ascertained before drawing conclusions, especially in connection with the older tilted forma- tions, that much careful geological work is yet to be done before reliable ratios can be deduced. Length of time since the Glacial period. The facts with regard to the present rate of recession of Niagara Falls have been used for calculating the length of time since the Glacial period. The argument has been presented thus. Niagara has made its present gorge by a slow process of excavation, and is still prolonging it toward Lake Erie. Near the fall, the gorge is 200 to 250 feet deep, and 160 feet at the fall, the lower 80 feet shale, the upper 80 limestone. The waters wear out the shale, and thus undermine the lime- stone. The rocks dip 15 feet in a mile up stream, so that the limestone at the fall becomes thicker, as retrocession goes on. The distance from Niagara to the Queenston Heights, which face the plain bordering Lake Ontario, is seven miles. The general features of the region are shown in the bird's-eye view, page 973. The new excavation began again at the Queenston Heights, and gradually extended southward to its present limit at the Falls. The time of beginning was after the filling of the channel with drift, which occurred during the retreat of the glacier. The rate of progress in the exca- 1024 HISTORICAL GEOLOGY. vation was estimated by R. Bakewell, Jr. (son of the English geologist), in 1829, on the basis of facts received from a 40-years' resident. His estimate was about three feet a year. Lyell, who was at the Falls in 1841 with James Hall, reduced the rate to one foot a year, making the elapsed time about 31,000 years. The question has since been considered by other geologists. G. K. Gilbert, taking as data (1) a map made in 1842, after a careful survey by Blackwell in 1841, and published in the K Y. Geological Report of J. Hall (1842), (2) another, made 33 years later, by the U. S. Army Engineers, and (3) a third, made in 1886 by R. S. Woodward, concluded that the rate of cutting, supposing the conditions to have been uniform, was about five feet a year, and the length of time about 7000 years; but he observes, that instead of uniform conditions, there have been great variations in the height of the fall, and in the amount of water, and that the deduced rate cannot be safely accepted (Ann. Rep. Smithsonian Inst. for 1890). That the investigation is beset with doubt is evident from the remarks on page 987, and also x by the various conclusions of recent writers on the subject. W. Upham, on the grounds stated in his various papers, makes, the time 6000 to 10,000 years. J. W. Spencer, in his latest interpretation of the facts (1894), arrives at the conclusion that the excavation of the channel required 32,000 years. But, as already shown, the amount of water now discharged by the river is no measure of that during the Champlain period of moist climate and expanded but gradually diminishing lakes, and no other safe basis for an estimate is known. As the amount of water then was almost certainly much larger than now, the lower estimates are probably nearest the truth. A similar estimate has been made by K H. Winchell (Final Rep. Geol. Minnesota) for the rate of recession of the Falls of St. Anthony on the Mississippi at Minneapolis (page 973), with the result that the elapsed time was probably about 8000 years. The rate of progress in a peat-bed, and that in a thickening deposit of stalagmite in limestone caverns, are other uncertain data that have been employed for deducing the length of time since the Glacial period. The amount of stalagmite is dependent on the amount of carbonic acid or organic acids in the filtrating waters, and partly on the texture of the limestone. The results of such calculations do not appear to have any geological or archaeo- logical value. Length of geological time according to geological evidence. The facts from geology used as a basis for calculating the length of geological time since the Archaean are : the rate of sedimentation or accumulation, and the rate of erosion or denudation, the former usually made dependent on the latter. The rate of denudation is generally based on the results obtained by Humphreys and Abbot from the Mississippi arid its drainage area, and related results from the study of other rivers. The rate of sedimentation obtained from the Mississippi gives an average of one foot from the whole GENERAL, OBSERVATIONS. 1025 drainage area in about 6000 years. The rate usually taken is one foot in 3000 to 7000 years. The rate 1 to 3000 was deduced by S. Haughton (1880) from the rate of sedimentation of the following rivers : the Mississippi, 6000 years ; Ganges, 2358 ; Hoang Ho, 1464 ; Yang-tse-Kiang, 2700 ; Ehone, 1526 ; Danube, 6846 ; Po, 729 years ; the mean of which is 3090 years. He adds that since the sea bottoms are to the land surfaces as 145 to 52, the rate at which the sea bottoms are becoming silted up, that is to say the present rate of formation of strata, is one foot in 8616 years. Thence, supposing the rate the same as now for all past time from the Archaean onward, the whole duration of geological time is 200,000,000 years. But Haughton included in the thickness of the terranes, 60,750 feet of Archaean, or over one third of his total (177,200 feet). Deducting for the Archaean, the length of the rest of geological time would be about 130,000,000 years. Mellard Reade makes the time since the Archaean, on the same kind of basis (taking the mean area of denudation as one third the entire land area, and the rate of denudation one foot in 3000 years), 95,000,000 years (1893). C. D. Walcott deduces, for the elapsed time, 70,000,000 years (1893) ; H. H. Hutchinson, 600,000,000 years (1892) ; M'Gee, including in his basis the rate of denudation at Niagara, and giving credit to the extreme estimates of thickness of the early Paleozoic formations, 6,000,000,000 years (1893). All these estimates proceed on the solid basis of existing facts. Yet in deriving them the extreme difference between the existing earth and that of the geological past was not taken into account. Going back in geological time, the rock-making portion becomes more and more widely marine, and rivers have correspondingly diminished size and drainage areas. But, at the same time, climates become warmer and precipitation therefore increas- ingly abundant ; and through Paleozoic to earlier time the eroding carbonic acid and oxygen of the atmosphere are increased in amount, and corro- sion thereby was proportionately greater. Even as late as the Middle Cretaceous, the western half of North America was an open sea with its large and small islands. In the Paleozoic, and still more in the Archaean, the whole continent was in a like condition; and the Continental seas had only little streams and drainage areas to supply sediment for the thick formations, so that the sea did much more than half the work in its slow way. Further, changing climates have occasioned changing rates of erosion and sedimentary deposition ; and have made, over large continental areas, times of great precipitation to alternate with times of prevailing drought, and times of full lakes and of large hard-working rivers, with times of dwindled or feeble waters. In addition, the deposits of one period have often been largely denuded to make those of the following ; and the chief sources of all sediments are Archaean. Attempts therefore to find, in the results of aqueous action, a definite measure of any part of the geological past necessarily lead to very doubtful results. Length of geological time on evidence from terrestrial physics. Kelvin pointed out in 1862 that a limit to the earth's age is fixed by the known DANA'S MANUAL 65 1026 HISTORICAL GEOLOGY. facts as to the rate of downward increase of heat and the rate of loss of heat into space; that if the earth had cooled less than 20,000,000 years since, the internal heat would have been greater than now ; and if more than 400,000,000 years, there would have been no sensible increase of heat down- ward ; and he suggested a probable length of 100,000,000 years. The bearing of the facts as. to tidal retardation, and his hypothesis with reference to the origin and age of the sun's heat, gave him other arguments on the question ; but the conclusions are less well based than that from rate of cooling. Tait, arguing from the effect of tidal retardation on the figure of the earth and the rate of cooling, concluded, that the time which can be allowed to geologists is something less than 10,000,000 years ; and, in view of the supposed origin of the sun's heat (by the falling together of masses of matter), that the time the sun has been illuminating the earth is not more than about 15,000,000 or 20,000,000 years ; and, again, that the supposed concussion would have made heat enough to last the earth 100,000,000 years. Croll has some speculations on this subject in Chapter xxi. of his Climate and Time. Newcomb says : " If we reflect that a diminution of the solar heat by less than one fourth its amount would probably mean an earth so cold that all the water on its surface would freeze, while an increase of much more than one half would probably boil all the water away, it must be admitted that the balance of cause which would result in the sun radiating heat just fast enough to preserve the earth in its present state has probably not existed more than 10,000,000 years." The first of Kelvin's methods mentioned above has been adopted by C. King (Am. Jour. Sc., 1893), with new data, derived from experiments by C. Barus, with regard to the latent heat of fusion of the rock diabase, its specific heat when melted and when solid, and its volume expansion between the solid and melted state, besides other points bearing on the subject. The conclusion reached is that the earth's age is probably 24,000,000 years. The safe conclusion from all the Geological and Physical facts is that Time is long, very long ; long enough for the development of all the earth's rocks, mountains, continents, and life. Geologists have no reason to feel hampered in their speculations, while the extreme results of calculation are 10,000,000 and 6,000,000,000 years. CLIMATAL DEVELOPMENT. A globe that has slowly cooled from fusion, and has had in the past, as now, a sun that is losing heat like itself, must have been a globe also of cooling climates. But its orbit has wide variations, and the sun, it is supposed, its varying phases. Moreover, the present era is a time of mild climate compared with that of the Glacial period which preceded it; and hence the cooling of the climates has not been continuous and regular, but one by oscillations, in which refrigeration was real, though often passing through extremes in both directions. GENERAL OBSERVATIONS. 1027 Yet, notwithstanding these sources of change, no good evidence in all Paleozoic time, except near or at its end, has been found in the fossils or the rocks, of zones in the earth's climates or of variations in temperature. North America shows in its large coal formation, as compared with that of Europe, that it had then, as it has now, the moister climate ; and therefore that the system of winds was the same as in Recent time, and hence that the system of oceanic currents was the same. Some difference must have existed, and more in the atmosphere than in the waters ; but it was not enough to modify, as far as has been ascertained, the marine fauna of the globe. Uniformity in climate in the northern hemisphere is favored by unobstructed oceanic currents. In the later part of the Permian, or at its close, a cold epoch occurred (page 737). At the same time happened one of the earth's most general exterminations of life. But large continental areas were then rising, and the Antarctic Continent was elevated and greatly extended; so that the elevations may have been the cause of the cold. After the close of Paleozoic time, zones become apparent (page 791). But even in the earlier part of the Cretaceous period, Cycads abounded in the northern polar regions, showing only a small decline in mean tem- perature since the Cambrian. After the Middle Cretaceous, a more rapid decline began (page 872) ; but, concordantly, large continental elevations were in progress. The increasing elevations during the later Tertiary cul- minated in the Glacial period of the Quaternary. Thus, throughout the earth's history since life began, the only cold epochs of which proof has been found occurred near or at the close of the Permian, at the close of the Triassic, and during the Glacial period. At the close of the Cretaceous, another epoch is suspected to have occurred, but without direct evidence. The post-Permian and Glacial cold occurred at times when the Antarctic Continent had great extent, and therefore when the earth's polar diameter had unusual elongation. Since the Glacial period, the polar lands have again become submerged ; but, inasmuch as Greenland affords evidence of continued subsidence, it may be questioned whether a time of minimum for the polar diameter is yet reached. This review of the extremely slow decline of temperature in the earth's climates during its lifetime, be it 10 millions of years or 600 times this, with traces of only three or four epochs of cold in the course of the millions, is calculated to give the impression that the eccentricity cycle in the earth's orbit is a very ineffectual epoch-making agency. THE EARTH'S DEVELOPMENT. The evolution of the earth's continents and their surface features is one of the two great subjects in the science of Geology. The idea Continents always Continents announced by the author first in 1846, has been affirmed 1028 HISTORICAL GEOLOGY. by all that has since come to light, and Geology now has, as regards North America, a record of the chief consecutive events in a continuous process of development. It has become manifest also that the development has gone forward not simply by enlargement about a nucleus, but through successive stages of work in Interior seas, having, in general, Archaean confines ; and that the great Interior Continental sea was not due to a return to oceanic conditions, but a phase in this endogenous feature in the method of progress. Europe also had its interior seas, and Asia, the two almost one; and so also had Australia, for the later facts show that in Cretaceous, or Cretaceous and Tertiary time, the Australian continent was divided in two by such interior waters. An exception to the general principle has been made by putting a hypothetical continent in the Indian Ocean. But the facts suggesting the hypothesis have been shown to be explained otherwise. A detailed review, in this place, of the steps in the process of develop- ment is not necessary. The closing pages of the Dynamical Geology, 391 to 396, are an appropriate continuation of these remarks on the earth's development. With regard to the hypothesis on page 396, respecting the alternate or zigzag arrangement of the continents, geological history affords no satisfactory testimony. There is only the interesting fact that the ore belt along the Andes of South America is continued through the nearly east and west bend of Central America to the Kocky Mountains and extends on northward to Wyoming, with remarkable similarity in its ores and the age of the veins. Whether the supposed continental displacement gave this displacement to the deep-seated ore region that in the earth's later eruptive periods supplied the ore ; or whether the similar position of the ore veins was due simply to a like position of the two continents with reference to the Pacific oceanic basin, it is not safe to say. Details with regard to continental development have been given in the chapters on Geographical and Geological progress, closing the accounts of the Lower Silurian (page 524), the Paleozoic (page 714), the Mesozoic (page 867), and the Tertiary (page 932). PROGRESS IN THE EARTH'S LIFE. General principles with regard to the progress in the earths life. The Animal and Vegetable Kingdoms studied by science comprised, not very long since, only living species. Through the revelations of geology they now include, in addition, the life of an indefinite succession of faunas, through the past ages up to, if not over, the borders of Archaean time. As a consequence of these developments, the following principles were early announced with respect to the progress in the earth's life : I. Progress from aquatic life to terrestrial life, commencing in the waters- in an era of nearly universal waters, and reaching its higher stages over the land. GENERAL OBSERVATIONS. 1029 IT. Progress from the simple to the complex or the more specialized; animal life, commencing with Protozoans, the simplest of species, without .special organs of any kind Radiolarians, the minute, silica-secreting, Khizopod-like kinds, having been reported (1894) from rocks of Archaean time and becoming displayed in a few comprehensive structural types, the simpler forms of which appeared in early time, and the more complex successively afterward ; the new organs required in the highest manifesta- tions of a type being only developments through modification of the older, or better appliances evolved from the structure for carrying forward old processes. III. The succession under a type parallel to some extent with the embry- onic stages in related living species, part of the early life of the globe repre- senting in some points the embryonic or young life of to-day. IV. Early types, often a combination of two or more types that were afterward differentiated, that is, became separate, independent branches in the sj^stem; synthetic types of Agassiz, comprehensive and generalized types of others. V. The earlier species under a type often multiplicate in structure, and losing this feature with rise in grade (pages 421, 437, 486). VI. The culmination of types, followed by degeneration, and often ex- tinction, at various times along the successive eras. VII. In the degeneration of a type, often a partial return to some of its early characteristics. VIII. The Animal kingdom, one in system from the beginning, the grander divisions of modern time being, to a large extent, those of the ear- liest Paleozoic (page 486), and some Paleozoic genera still having their species. The facts prove unity in system of life as well as in organic and physical law. IX. A head ward concentration or cephalization of the structure attend- ing generally a rise in grade, and the reverse, or decephalization, a decline. X. The localization of tribes in time, or chronographically, involved in the physical progress of the earth, that is, in its progressing climates, and its conditions as to water and land. As now there are different zones, and various localizations of species on going from the equator to the poles, so there were necessarily successive phases and increasing diversity in the life of the world on passing from the warm conditions and nearly universal seas of early time to the present age of frigid polar regions and greatly differen- tiated seas and lands. Evidence with reference to evolution by variation. The propositions above stated read like the heads in an argument for the evolution of the kingdoms of life. They were so recognized many years before Darwin's first publica- tion on this subject. Most of them were used by Agassiz in his lectures on development, by which he meant evolution ; and evolution based on paleon- 1030 HISTORICAL GEOLOGY. tological study, having therefore the successional lines which such study- ascertains ; but different in method, the change in species being dependent, in his view, on creative acts, and not on natural variation. All students of nature, with a rare exception, then believed in permanence ; for Lyell's chapter against the transmutation of species, in the successive editions of his Principles of Geology, had seemingly settled the question against Lamarck by scientific argument. It was not till 1859 that Darwin's work was pub- lished on the Origin of Species by means of Natural Selection, or the Preser- vation of Favored Races in the Struggle for Life. The principles above stated are all in accord with a theory of evolution ;. and, through the added facts of later years, they favor the view of evolution by natural variation. Some of these added facts are the following : Botan- ists find numerous cases among existing species in which, owing to the many varieties, no line can be drawn between allied species ; and other cases in which modern species of plants are but slight modifications of fossil Tertiary species, some too slight to be called distinct species, and others more diver- gent up to those of good distinctive characters. Similar facts occur as a consequence of migrations, among animals as well as plants. Arctic America contained, in Tertiary time, plants so much like species existing in the forests of both temperate North America and Japan (page 939), that the former have been pronounced the undoubted progenitors of the latter. Along the Pacific coast and Gulf coast of Central America there are so many iden- tical and nearly related species of aquatic animals that migration during a time of submergence of the narrow strip of land, with subsequent variation, is regarded as the only reasonable explanation. These and other observa- tions have proved sufficient to make all zoologists of the present day, like the botanists, believers in a system of Evolution by variation. It is admitted that in the geological record cases of unbroken gradation between species are of rare occurrence. But the geological record bears evidence, in all parts, of imperfections. It is imperfect, (1) because, under the most favorable circumstances, only a small part of the existing species could have been fossilized ; (2) because in all lands there are great breaks in the series of rocks, as is known from comparing the rocks of different conti- nents, and even different regions on the same continent : (3) because fossil- iferous rocks |re almost solely of aqueous origin, and consequently they contain exceedingly little of the terrestrial life of the ancient world one species of Bir being all yet discovered in the world's rocks of the Jurassic period, and twl species of Mammals all that are known from the American Triassic beds ; (4) because marine strata that were formed around the land when it was at a higher level than the present are now buried in the ocean, and are therefore inaccessible, a condition that has affected half the borders of a continent for several successive periods ; (5) because only a small part of the rocks of a continent are open to view. This subject has been abun- dantly illustrated in the preceding history of the formations and their life. But transitions have been nearly filled in so many cases, and are indi- GENERAL OBSERVATIONS. 1031 cated so plainly by the very gradual steps in the successional lines ; the progress of rudimentary organs may so often be traced from an early con- dition of good size to that of rudiments, and variations in existing species are so often wide and perplexing to the systematist, that the evidence in favor of evolution by variation is now regarded as essentially complete. The argument from the facts presented on page 929, respecting the descent of the Horse, is strengthened by the occurrence among modern horses occasionally of a small pair of hoofs growing from the extremity of the splint bones of each foot the old toes lost by descent back again ; and more rarely by the growth of a full-sized toe from one of these bones, on all the feet, approximating thus to horses of the later Tertiary (Marsh, Am. Jour. Sc., xliii. 1892). Birds, now standing apart from other Vertebrates so stiffly, as animals with feathers, short tails, and bills without teeth, in former times had teeth in their jaws, and long tails, like Reptiles. Moreover, in the Reptilian age, there were biped Reptiles, with the hollow bones and some other characteristics of Birds ; and also Mammals that laid eggs like Birds and Reptiles, as they continue now to do in Australia. There are, however, some large blanks in the series which are yet unex- plained, although investigators have been at work over the subjects for scores of years. One of these is the apparently sudden appearance of plants of the tribe of Angiosperms, the most common kind of Recent time, in the Lower Cretaceous ; another, the still more remarkably abrupt introduction of ordi- nary or placental Mammals as successors to the Marsupials at the commence- ment of the Tertiary ; another, the introduction of well-characterized Fishes, without the discovery of their precursors. Such facts excite, at the present time, interest in further study, but not doubts as to the general system of progress. Already a small slender fossil, with a blade-like sculling tail and terminal mouth, the Palceospondylus Gunni, from the Devonian of Caith- ness, Scotland, has been described as probably a primeval Lamprey (an eel-like Cyclostome, page 403). But, if correctly referred, there is still a very wide interval between it and the early Placoderms. Some other general facts respecting successional lines, are the following : The lines of succession seldom connect the grander divisions of^Jftsses or tribes. None lead directly from Macrural to Brachyural Crustaceans, or from An^mipod to Isopod kinds. Instead, the group of Anomourans, intermediate between the two tribes first men- tioned, was the course of successional lines in geological history, and of branches to both the Macrurans and Brachyurans. In a similar way the Anisopods, intermediate between the Isopods and Amphipods, or the typical Tetradecapods, were the source of branches to these tribes. The principle is in accordance with that respecting comprehensive or syn- thetic types, for the Anisopods and Anomourans are of this nature. A line leads direct from the higher Ganoids to the Amphibians ; but, instead of lines from Amphibians to Reptiles, and thence to Birds or to Mammals, all three groups Reptiles, Birds, and Mammals were probably derived directly from the Amphibians. Instead of succes- sional lines between Ungulates, Carnivores, and Quadrumana, these three groups were probably derived, as Cope has remarked, from some common tribe in the earliest Eocene. No successional lines among Insects appear to have passed between the higher tribes of 1032 HISTORICAL GEOLOGY. Neuropters, Orthopters, Coleopters, Lepidopters, Hymenopters ; but each was derived from some early comprehensive forms. The results of degeneration afford other series of facts of the highest importance with reference to the origin of species. Some of them, and a few of the principles they illus- trate, are mentioned on pages 717, 931. Two systems of evolution. LAMARCK, in his system of Evolution (Phil. ZodL, 1809), laid down as one chief cause of variation, the use and disuse of organs or parts, use causing enlargement, and disuse a dwindling even to disappearance ; and one of his illustrations was drawn from the difference in length of wing of the tame and wild Ducks. He put forth, as other sources of change, the surrounding physical conditions and their often abrupt changes, and referred also, in an imperfect way, to the effect of biological associations, or the influence of the living species of a region on one another. The im- portance of the principle of heredity was also recognized. He added to his system the principle a tendency upward. DARWIN, in his work of 1859, recognized the obvious causes of variation, but claimed that these, and all means of change, derived their efficiency from action under the principle of "Natural Selection," as indicated in the title of his work. He elucidated the subject of evolution by many illustrations of the effects of breeding and culture under man's care and guidance ; by his study of variation among living plants and animals, wild and domesti- cated, publishing a separate work of great value on Animals and Plants under Domestication ; by full illustrations of the laws of heredity; and by new facts, almost a revelation to science, relating to the living environments of species, and the consequent interdependence and interaction of associated kinds in both kingdoms of life. According to the principle of natural selection, " an animal or plant that varies in a manner profitable to itself will have, thereby, a better chance of surviving," and of contributing its qualities and progressive tendency to the race, while others not so favored, or varying disadvantageously, disappear. The favored ones, or the " naturally selected," are one or two, or a few, of a herd, or of a region; and the unfavored ones, fated to disappear because unadaptable, include, theoretically, all the rest. The principle of selective breeding is used in the development of the favored ones ; for these have to be separated from the rest of the herd for success, as in man's selection. The adaptations are to any kind of condition, whether favorable to the highest or to the lowest developments, so that progress under the principle may be upward or downward. The origin of variation is not considered. Everything in nature varies, and changing conditions are always adding to the variations. However produced, the individual that is profited by a variation survives, propagates its characteristics, and becomes the type of a species, while "multitudes" are left behind in the struggle with adverse environments; and thus the new species, in the end, stands widely apart from other species. In the expression, "preservation of favored races. in the struggle for GENERAL OBSERVATIONS. 1033 life," the direct effects of struggle or labor on the individual, that is, the beneficial and other effects of struggle itself, are not intended, though not excluded; only the effects of struggle or strife on disappearings and sur- vivals, under the changing conditions, are referred to. Augmentation of variations by interbreeding fundamental in evolution. Man, by selective breeding carried on for successive generations, has obtained -cattle with long horns, short horns, and no horns ; fowls with large combs on the head, with no combs, or with a rosette of feathers in place of the crested comb, with bare legs and with feathered legs, with long spurs and long legs for fighting, and with no spurs and short legs, and with great diversity of color; Pigeons with long bills and with short bills, giving them characters belonging to different tribes of Birds, with long or short legs, with the fan- like tail of a Peacock and an attendant increase in the number of feathers. And, similarly, diversity has been obtained in the case of many other species. The varieties obtained range through a vastly wider diversity of characters than occurs under any species in nature. It is perceived that the law of nature here exemplified is not "like produces like," but like with an increment or some addition to the variation. Consequently, the law of nature, as regards the kingdoms of life, is not permanence, but change, evolution. Great plasticity in organic structures under variant agencies. This is another principle taught by the above-mentioned facts. This plasticity under any type is usually most prominent in one or two of the kinds of organs, and consequently it leads to the evolution of species in lines, deter- mining genera or natural groups. " A tendency upward." determined, in the Animal Kingdom, by the existence of a cephalic nervous mass or brain. This principle is explained on page 439. Articulates and Vertebrates first appear as multiplicate species : as exem- plified in Worms, the earliest Crustaceans, and Fishes, and in the Myriapods, successors to the Worms. Through subsequent changes, types having a definite or normal number of parts are introduced, as Insects after Myria- pods (page 721), Amphibians after Fishes (page 725), and so on. In degeneration, Reptiles and Mammals, in some cases, have become mul- tiplicate: as exhibited in the vertebrae and teeth, and sometimes in the phalanges and number of the digits. (Pages 797, 931.) Natural selection not essential to evolution, variations being effectual with- out it. The theory of natural selection is based on the assumption that variations come singly or nearly so, and that the selected are therefore few compared with the multitudes that disappear. The idea is derived from facts afforded by domesticated or cultivated races. But such races are in a large degree artificial products, selective methods carrying the individuals rapidly in the direction of the variation, and producing, in a few scores of generations^ divergencies that in wild nature would require thousands of years. The structures are therefore in a strained or artificial state, and 1034 HISTORICAL GEOLOGY. deteriorate when care ceases. But in wild nature variations are, in general,, the slow and sure result of the conditions the organic conditions on one side and the physical and biological on the other; they should occur,, generally, in a large part of the associated individuals of a species ; and being Nature-made, the results are permanent. When, therefore, a variation appears that admits of augmentation by continued interbreeding, progress, should be general; and the unadaptable few should disappear, not the; multitudes. 7 ' Under such a system of evolution, evolution by regional progress, the causes of variation mentioned by Darwin are all real causes. But they act directly, after the Lamarckian method, without dependence for success on the principle of natural selection. Use and disuse, labor, strife, physical! changes or conditions, and organic influences act as such, and have their direct effects. The plants that migrated in the Tertiary from the Arctic regions southward over Japan and North America, and became new species on the way, simply changed. That is the sum of knowledge on the subject. Man affords an example. The gradual gain of some races in lands and supremacy, and the disappearance of the inferior races, is an example of the- Survival of the Fittest, or Natural Selection. But the superior races de- rived the power which led to their survival and preeminent position through favoring conditions in environments, that is, in geographical, geological, and! biological conditions and resources ; through the powers of endurance, the courage, the mind power, the will power, which conflict with nature and with other races of men in the world is fitted to develop ; and through the power and self-assurance which comes of a high moral sense. Hence victory, sur- vival. The survival of the fittest is a fact ; and the fact accounts in part for the geographical distribution of the races of men now existing and still in progress ; but not for the existence of the fittest, or for the power that has determined survival. Natural selection, a means of determining the successive floras and faunas- of the world; a prominent cause of the geographical distribution of species. Natural selection is literally selection, survivals ; the survivors are those that continue on to make faunas and floras. Independent derivation of allied species. The existence of related species under a genus or family on two or more continents, or in widely distant regions, has brought up the question whether such occurrences are not due in some cases to independent derivation. Migration accounts unquestionably for a large part of them ; but it is doubtful whether it accounts for all. If not for all, if the evolution has gone forward parallel- wise on different continents, then organic law is not only the source of change, the environments subordinate in influence, but the source of a system of changes in the progressing evolution. The subordination to the law of cephalization that anterior concentration in the animal structure,, involving posterior abbreviation, attends progress in grade accords with this idea of organic control. GENERAL OBSERVATIONS. 103& This view of the subordination of organic evolution to general laws is sustained by the paleontologist Professor A. Gaudry, of Paris, in his review of the parallelism between Europe and America in the succession of types from the Cambrian upward (Bull. Soc. Geol. de France, December, 1891). He compares the correlate tribes through the successive stages of progress, and the gradual changes by which old characteristics disappeared and new features were developed for the two distant regions, notwithstanding the differences that existed in climatal and other conditions ; and he concludes that these and similar facts are not all explainable by migrations, but only by evolution under general laws of progress. Origin of species. The origin of the special causes for each line of change or variation, which Darwin did not undertake to study out, is yet very imperfectly understood. The paragraphs on the evolution of the Horse and the Artiodactyl, on page 929, and others bearing in the same direction, show some success. It is admitted that (1) bones will coossify if movement between them ceases ; (2) that the progressive enlargement of one organ or part may cause the dwindling of others adjoining ; (3) that running under an impulse would lead to a rising of the foot on the toes, to secure greater length of lever and greater speed; (4) that activity in the limbs may deter- mine adjustments in the position of the ankle bones fitted for greatest strength and security ; (5) that the use of the teeth may lead to increased complexity of structure. But from the statements with regard to the Horse and Artiodactyl, it may be thought possible, also, that the great elongation of the foot, chiefly of the metacarpals and metatarsals, would be a natural consequence of the rhythmic stroke of the foot in running, this inducing a variation that was continued in growth by interbreeding. And this apparent success in ex- plaining leads to the suggestion that the graceful form, so general in fleet animals, may be a result of the free movements of all parts of the structure in running ; and that the horns in the Kuminants and other Ungulates may have come from a variation commenced by the strokes made by the forehead or front of the head, in conflicts. But another Artiodactyl, the " high-reaching " Giraffe, puts a check to speculation: for it has the anterior pair of legs much the longer, the foot portion alone three feet long; and the neck more than triple the ordinary length in Ruminants, owing to the great elongation of six of the seven vertebrae. The elongation of the legs has the same purpose as that of the neck "high-reaching in quest of food." The question comes up How should the Giraffe have had to run to make its fore legs grow faster than the hind legs, and what kind of antics would have started the change in the neck ? It has to be supposed that the requisite augmentative varia- tions were somehow begun, and that under interbreeding, accelerated growth went forward. But the origin of the variation is without explanation. And so it is for the most part throughout the Kingdoms of life. Enough is known to encourage study. 1036 HISTORICAL GEOLOGY. It is of no avail to speak of chance variations. The use of the word chance indicates personal ignorance. Chance has no place in nature's laws, and can have none in nature-science. Man's origin has thus far no sufficient explanation from science. His close relations in structure to the Man- Apes are unquestionable. They have the same number of bones with two exceptions, and the bones are the same in kind and structure. The muscles are mostly the same. Both carry their young in their arms. The affiliations strongly suggest community of descent. But the divergencies mentioned on page 1018, especially the cases of degeneracy in Man's structure, exhibited in his palmigrade feet and the primitive character of his teeth, allying him in these respects to the Lower Eocene forms, are admitted proof that he has not descended from any existing type of Ape. In addition, Man's erect posture makes the gap a very broad one. The brute, the Ape included, has powerful muscles in the back of the neck to carry the head in its horizontal position, while Man has no such muscles, as any one of the species can prove by crawling for a while on " all fours." Beyond this, the great size of the brain, his eminent intellectual and moral qualities, his voice and speech, give him sole title to the position at the head of the Kingdoms of Life. In this high position, he is able to use Nature as his work-mate, his companion, and his educator, and to find perpetual delight in her harmonies and her revelations. The search for " missing links " has been carried forward with deep interest during recent years. But although fossil skeletons have been found among the remains of Pleistocene Mammals in Europe and America none show any indication of departure from the erect posture, or have smaller brain cavity than occurs among existing races of Men. The most probable regions for the discovery of precursor forms are those of Africa and the East Indies. Already, since these closing pages were first in type, the report has come of the discovery, in the Pleistocene deposits of Java, of an imperfect cranium, a femur bearing evidence of prolonged disease, and a molar tooth, which the describer, E. Dubois, has named Pithecanthropus erectus, placing it between the Man-Apes and Man. Others make the remains those of a low-grade Man, or of an idiot. Since Man's structural relations are, in several respects, closest with the precursors of the Quadrumana (p. 1017), his derivation from any known type of Man- Ape has been pronounced impossible. Whatever the results of further search, we may feel assured, in accord with Wallace, who shares with Darwin in the authorship of the theory of Natural Selection, that the intervention of a Power above Nature was at the basis of Man's development. Believing that Nature exists through the will and ever-acting power of the Divine Being, and that all its great truths, its beauties, its harmonies, are manifestations of His wisdom and power, or, in the words nearly of Wallace, that the whole Universe is not merely depen- dent on, but actually is, the Will of one Supreme Intelligence, Nature, with Man as its culminant species, is no longer a mystery. INDEX. INDEX. A star (*) after the number of a page indicates that there is a reference on the page to a figure of the species or object mentioned ; and a section mark () implies that the page contains a definition, explanation, or characteristic of the word or object mentioned. Aa (lava-stream), 287*, 288, 289 Aalenian, 790 Aar Glacier, 237, 248, 251 ; investi- gations by Hugi and Agassiz, 243 Abies, 859 Abietites dubius, 839 ; Linkii, 834 Abrasion, 131, 159, 168, 202, 804, 805, 806, 941 ; assorts in propor- tion to hardness, 169 ; see also Glacial abrasion, Scratches Abrolhos Islands, 867 Abyssal depths of the ocean, 229 Abyssinia, 26 (plateau), 33, 34, 177 Acacia, 921 Acadian area of Carboniferous and Subcarboniferous, 635 period. See Cambrian, Middle protaxis, 444 Range, 389, 391, 732 Triassic area, 740, 741 trough, 461, 467, 536, 537, 541, 543, 558, 633, 708, 715, 732, 743 upturning, 736 Acalephs, 430 Acanthaspis armata, 588* Acantherpestes, 701 ; major, 691 Acanthoceras Lyelli, 865; mammil- lare, 855, 865; Mantelli, 866; Rhotomagense, 866 Acanthodes, 620 ; affinis, 620* ; pris- cus, 620 Acanthodians, 416 Acanthopholis horridus, 863 Acanthotelson Eveni, 691 ; Stimp- soni, 678*, 691 Acephals, 424 Aceratherium, 926 Acervularia, 625 ; pentagona, 592 Achaenodon, 918 Achyrodon, 789* Acid. See Boracic acid ; Carbonic ; Humus ; Organic ; Sulphuric Acidaspis, 513, 515, 520, 521, 561, 567, 568, 579, 586, 591, 599 ; Bar- randii, 565* ; Brightii, 565*, 567 ; callicera, 587*, 591 ; coronata, 567 ; hamata, 567 ; Jamesii, 520 ; Rom- ingeri, 587*, 599 ; tuberculata, 561, 562*, 578, 579 Acipenser, 923 Acleistoceras, 591, 602 Aclis robusta, 690 Aconcagua, 296 Acrocrinus, 690 Acrodus, 772 (first), 783 ; minimus, 416*, 774 ; nobilis, 416* Acrogens, 435 Acrolepis, 705 ; Sedgwickii, 707 Acrothe'e, 481 ; Matthewi, 475* Acrotreta, 520 ; gemma, 471*, 516, 573 ; subconica, 573 Actinia, 429*, 431, 516 Actinoceras, 501, 546, 549, 567; Bigsbyi, 506, 508*, 514; crebri- septum, 516, 524 ; verum, 866 Actinoconchus planosulcatus, 646 Actinocrinus, 520, 567, 597, 646, 690 ; proboscidialis, 640*, 646 ; simplex, 567 ; tenuistriatus, 625 Actinocyclus Ehrenbergii, 894* Actinoids, 431, 525 Actinolite, 67* Actinolyte, 89 Actinopteria, 621 Actinoptychus senarius, 437*, 894* ; undulatus, 894* Adams, Mt., 296 Adapisorex, 925 Adelsberg cave, 207 Adipocere, 143, 154 Adirondack Mts. and region, 85, 204, 384, 442; Arctic plants on summits of, 945 Adjutants, 923 Admete viridula, 984 Admiralty Islands, 38, 39 Adobe, 195 Adocus agilis, 850; beatus, 850; punctatus, 850 Adriatic Sea, 41, 212 .^Echmina, 562 ^Eglea, 708 ^Eglina, 521 ; grandis, 520 ; mira- bilis, 520 ^Egoceras capricornus, 781* ; Jame- soni, 790 ; planorbis, 790 ^Egyrite, 85 ^Elurodon, 919 ^Eon, 406, 407 ^Epyornis, 54, 1014, 1019 1039 Afghanistan, 920 Africa, 17, 21, 22, 23, 26 (plateaus), 30, 31, 33*. 51, 165, 297, 394, 395, 406, 435, 674, 737 ; volcanoes in the Bight of Benin, 296; coral reefs of eastern coast, 145 , Carbonic rocks in, 632, 693 ; Up- per Silurian, 563; Triassic, 632, 741 ; Jurassic, 873 ; Cretaceous, 857, 859, 873. See further South Africa Agalmatolite, 68 Agalmatolyte, 84 Agaricus, 688 Agassizocrinus, 690 Agassizodus, 692; variabilis, 680* Agathaumas, 828, 847; sylvestris, 847, 856 Age of the Earth, 1023 Agelacrinites, 516 Agelacrinus BiUingsi, 514 Agnostus, 473, 475, 481, 482, 486, 500, 516, 520, 521; Acadicus, 476*; interstrictus, 476*; Kje- rulfi, 482; nobilis, 473*; Rex, 481*, 482 Agnotozoic, 445, 447 Agoniatites, 599 Agriochoerus, 918 Agriomeryx, 918 Agui Range, 365 Alabaster, 69 Alachua clays, 891 Alaska, 23, 234 (snow-line), 297, 582, 948 (fiords) , Triassic in, 747; Cretaceous, 818, 820, 834, 868, 872 (climate) ; Tertiary, 892, 893, 939 ; Glacial, 945, 948 "Albatross," 60,230 Albemarle Sound, 224* Albert Mine, N.B., 639 Albertia, 770 Albertite, 662 Albian group, 815, 858, 859, 865 Albirupean group, 819 Albite, 64, 82, 83 Alca impennis, 1014 Alces Americanus, 1002 Alcyonaria, 431 1040 INDEX. Alcyonium, 431 Alcyonoids, 481, 525 Alder, 837, 922 Alethopteris, 639, 645, 671, 685, 698, 699, 704, 756; discrepans, 622; gigas, 705; Helen*, 645; lonchi- tica, 670*, 689 ; Serlii, 689 ; Whit- byensis, 791 Aleutian Islands, 40, 296 Algae, 56, 60, 72, 79, 140, 153, 156, 241 ; the earliest plants, 409*, 441, 454 ; in hot waters, 152, 308, 437, 441,454 Algeria, 920 Algerite, 320 Algonkian formation, 445, 447, 469 AUeghany Mts., 41, 106, 188, 636, 638, 745; plants on summits, driven south by the ice, 946 Alligator, 54, 55, 681 Allodon, 768 ; fortis, 767* ; laticeps, 767* Allomys, 918 Allophane, 638 Allorchestes, 347 Allorisma subcuneata, 675*, 690 Allosaurus, 766 ; medius, 836 Alluvial cones, 99, 194, 195*, 196 Alluvium, 81, 98, 191, 198, 200, 228, 366 Almond, 921 Alps, 23, 32, 110, 233, 234 (snow- line), 265, 266, 310, 367*, 368* 391, 463, 738, 812, 943 ; coal-formation, 734 ; glaciers of, 235*, 236*, 237*, 239, 243, 244, 248, 251 ; great fault in, 734 ; section, east of Lucerne, 102* , Archaean in, 368 ; Upper Silu- rian, 573 ; Triassic, 757, 768, 769, 773, 774; Jurassic, 774, 780, 791, 793; Cretaceous, 859, 864; Ter- tiary, 347, 367, 380, 919, 920, 921, 982 (upturning), 936 (eleva- tion) Altai Mts., 32, 33, 200, 568, 569 Altamaha grits, 891 Alum Bluff sands, 890, 891 Alum shale, 80 Alumina, 61 Aluminum sulphates, alums, 119, 126, 138, 294, 335 Amaltheus ibex, 790 ; spinatus, 790 Amargura Island, 296 Amazon River, 24, 30 ; drainage area of, 172; eager, 212, 215; floods of, 177, 183 ; slope of, 173 Amazonian group, 867 Amber, 143, 838, 922 Amblotherium, 789* Amblygonite, 449 Amblypterus, 692, 702, 772 Amblyrhizainundata, 1001 Ambocoelia gregaria, 621 ; umbo- nata, 598*, 601, 620, 621 Ambonicardia Cookii, 837 Ambonychia attenuata, 514; belli- striata, 507* ; radiata, 511*, 516 Amboy clays, 837 Ambrym Island, 296 American continent, North, growth of, 714-716 418, 901 ; Amia family, 783, Amianthus, 319 Ammodon beds, 894 Ammonia, 124, 137 Ammonites, or Ammonoids, 402, 424, 869 ; Devonian, 869 (first) ; Permian, 686 ; Triassic, 756, 757*, 771; Jurassic, 749, 758*, 759*, 760, 781* (number of British), 791, 792, 793, 861, 869 ; Cretaceous, 812, 818, 836, 841, 842*, 855, 861, 862*, 865, 867, 869, 877 Ammonites, 757, 774, 916 ; acanthi- cus, 791 ; aspidioides, 790 ; Astier- ianus, 865 ; athleta, 791 ; auritus, 865; bifrons, 790; bimammatus, 790 ; biplex, 760, 791 ; Bucklandi, 790; Burgundise, 790; canalicula- tus, 790 ; cornplexus, 855 ; conca- vus, 760 ; cordatus, 790 ; cristatus, 865; decipiens, 790; Delawaren- sis, 854; Deshayesi, 864; discus, 790; ferrugineus, 790; Gallici, 866; Gaytani, 792; Gervillianus, 865 ; gigas, 791 ; Gowerianus, 790 ; Guadalupae, 855; Herveyi, 790; Humphriesianus, 790 ; ibex, 790 ; inflatus, 865; interruptus, 865; Jamesoni, 790 ; jugalis, 916 ; Ju- rensis, 790 ; Lamberti, 790; lautus, 865 ; Leonensis, 837 ; Lewesiensis, 862; M'Clintocki, 760, 792; macro- cephalus, 790, 791 ; rnammillaris, 865; Mariae, 790; Mississippien- sis, 854; Mullananus, 855; Mur- chisonae, 790; mutabilis, 790; Noricus, 865; Parkinsoni, 790, 791 ; pedernalis, 836 ; peramplus, 866; placenta, 842*; planorbis, 790; pleurasepta, 855; plicatilis, 790 ; ptychoicus, 791 ; radians, 790 ; radiatus, 865 ; Rhotomagen- sis, 866; serpentinus, 790; spi- natus, 790 ; suprajurensis, 791 ; Swallovi, 854 ; tenuilobatus, 790 ; Texanus, 855, 866; tricarinatus, 866 ; varicosus, 865 ; vespertinus, 867; Wosnessenski, 760 Ammonium chloride, 294 ; nitrates, 118 Ammosaurus, 753 Amnigenia, 612 Amoeba, 433 ; AmoeboSds, 419 Ampelite, 81 Amphibamus grandiceps, 682, 683*, Amphibians, 54, 409* (time range), 414, 415, 416, 417, 681, 706, 795, 796 , Reign of, 460 , Relation to Mammals, 794 , Paleozoic, 725-726, 727 , Subcarboniferous, 643, 644, 645*, 700 , Carboniferous, 657, 661, 674, 681, 682, 683*, 684, 692, 693, 703, 704, 726 , Permian, 686*, 687*, 706, 869 , Triassic, 742, 751*, 758, 772*, 796, 869 , Jurassic, 760, 796 , Cretaceous, 826, 869, 870 Amphibole, 67 Amphibolyte, 89 Amphigene, 85 Amphigenia elongata, 579, 590 Amphilestes, 789* ; Broderipi, 789* Amphion, 500, 502, 516, 521 ; Cana- densis, 502* Amphioxus, 418, 725 Amphipods, 420*, 421 , 438, 439,. 565, 707 Amphitragulus, 926 Amphitylus, 789* Amplexus, 552 ; Hamiltoniae, 601 Ampullina, Fischeri, 917; solidula, 916 Ampyx, 481, 500, 520, 521 ; nudus, 519*, 520 ; Salteri, 520 Amsopus Deweyanus, 751* ; graci- lis, 751* Amusium, 760, 917; Mortoni, 917; simplicum, 854, 855 Amygdalocystites, 514 Amygdaloidal cavities, 68, 98, 836,. 337, 342 rocks, 78 Amygdules, 339 Amynodon, 907, 918 Amyzon beds, 886, 893 Anabacia hemisphserica, 790 Anacodon, 918 Analcite, 68, 339 Analyses of bones, 73 ; of coal (see- Coal); coprolites, 73; corals, 72; granite, 82, 83; limestones; 78, 79 ; plants, 74, 75 ; shells, 72 ; vol- canic rocks, 82-89 Ananchytes, 59 ; ovalis, 854 ; ovatus,. 860*, 866 Anaptomorphus, 918 ; homunculus, 906* Anarthrocanna Perryana, 622 Anastrophia, 562, 579 ; interplicata, 548*, 551, 569 ; Verneuili, 561* Anatifa, 420*, 421 Anatimya papyracea, 855 Anchippodus, 904, 918; minor, 904*,, 905 Anchisauridae, 792 Anchisaurus, 753; colurus, 753* Anchitherium, 911, 919, 927 Anchor-ice, 232 Anchura abrupta, 854 ; Americana,. 841*, 855 Ancilla ancillops, 916 Ancodus, 918 Ancyloceras, 760 ; gigas, 865 ; Math- eronianum, 862* ; Remondi, 760, 837 Andalusite, 65*, 66, 83, 310, 315, 318, 319, 449 Andalusitic rocks, 82, 83, 84 Andes, earthquake in, 349 ; glaciers in, 977 ; height of, 26, 296 ; slopes of, 27, 31 ; snow line of, 234; vol- canoes, 296, 297 , Archaean in, 456 ; Carboniferous, 711; Jurassic, 760; Cretaceous, 857 ; Tertiary, 365, 392, 935 ; Qua- ternary, 392 Andesite, 64, 273 Andesyte, 86, 87, 272, 273, 276,, 301*, 304, 339, 341, 518, 811 rocks, 273, 274, 296 INDEX. 104T Andromeda, 887 ; affinis, 839 ; Par- latorii, 838* Andromedites, 922 Aneimites obtusus, 609*, 611 Angau Island, 150 Angiosperms, 409, 434, 435 ; Cre- taceous, 816, 831, 832*, 833, 837, 838*, 839, 859, 868; Tertiary, 895, 921 Anglesea, 309, 440 Anglesite, 335 Angoumian, 859, 866 Anguillaria Cumminsi, 854 Anhydrite, 69, 120, 121, 125, 128, 138 Animal kingdom, 9, 413, 414 Animals, geographical distribution, 52, 53; materials they afford to rock-making, 140-141, 144-152 and plants, distinctive character- istics, 413-414 Animikie group, 446, 469 Anisomyon, 855; borealis, 855; Haydeni, 855 Anjou, Faluns beds of, 926 Annabon Island, 297 (volcanoes) Annelids, 55, 157, 423, 427, 438, 720, 721, 723 Annularia, 519, 671, 685, 699, 704, 718 ; carinata, 704, 705* ; longi- folia, 689, 692, 704 ; minuta, 704 ; radiata, 704 ; Eomingeri, 560 ; sphenophylloides, 689, 692, 704 Anodonta, 837 Anotnalocaris Canadensis, 476, 477* Anomalocrinus, 516 Anomalocystites, 562 ; oornutus, 559* Anomalopteryx, 1014 Anomia, 828 ; argentina, 854 ; ephippoides, 915 ; micronema, 855 Anomocare, 482 Anomodontia, 688 Anomodonts, 688, 707, 772, 773 Anomcepus scambus, 752* Anomozamites elegans, 756* Anona robusta, 839 Anoplia nucleata, 579 Anoplophora lettica, 774 ; Munsteri, 774 Anoplotheres, 924 Anoplotherium, 926, 927; com- mune, 926 ; secundarium, 926 Anorthite, 64, 65, 82, 86, 87, 88, 273, 313, 318, 319, 323, 324, 802 Anorthite rock, 87 Anorthityte, 87f Ant. See Ants Ant-eater, 54, 925, 1002 Antarctic continent, 737, 798; in the Quaternary, 1019; see also Gondwana Land ice-barrier, 252 islands, 17 pole, 17 regions, 737 ; glaciers, 233, 241 ; volcanoes, 295, 296, 297 Antedon, 429 Antelope Park, 178 Antelopes, 924, 927 Antholithes, 674 ; Pitcairnae, 673* DANA'S MANUAL 66 Anthozoans, 431 Anthracerpes typus, 691 Anthracerpeton crassosteum, 703 Anthracite, 74, 315, 453, 648, 654, 655*, 657, 661, 695, 714, 732, 826 ; composition, 662, 663, 712, 713; in geodes, 493, 497 ; of the Cal- ciferous, 493 -, origin of, 713-714 Anthracoblattina, 691, 701 Anthracomartus, 691, 701; tri- lobitus, 691 ; Volkelianus, 703 Anthracomya carbonaria, 690 ; elongata, 690 ; Isevis, 690 Anthracopalsemon gracilis, 678*, 691 ; Hillanus, 691 Anthracosaurus Russelli, 682, 703 Anthracotherium, 918, 926 Anthracothremma robusta, 691 Anthrapalaemon dubius, 703; Gros- sarti, 703 ; Salteri, 701*, 703 Anticlines, 102*, 103*, 109*, 186*, 368*, 874* Anticosti Island, shore-platform of, 221 ; Lower Silurian in, 493, 533 ; Upper Silurian, 493, 533, 537, 539, 541, 563, 568, 573; species common to the Clinton and Ni- agara, 551 Antilope, 927 Antimony, 331 Antipathes, 55 Antisana(Mt.),26, 296 Antrim, 867, 938 Ants, 158, 419, 717, 783, 794 ; num- ber of Florissant, 901 Apatemys, 918 Apateon pedestris, 704 Apatichnus bellus, 752* Apatite, 63, 69, 79, 86, 143, 313, 447, 450, 453, 455 Apatornis, 852 Apatosaurus laticollis, 763, 764* Apennines, 41, 319, 775, 812, 920, 921, 927, 932 Aphanapteryx, 1019 ; Broecki, 1019 ; Hawkinsii, 1019 Aphanitic texture, 76 Aphelops, 911, 919 Aphis, Aphides, 419, 525, 901 Aphrodina Tippana, 854 Apia Island, 145* Apiocrinus, 778; Meriani, 791; Roissyanus, 778*, 779 Apiocystites Canadensis, 550 ; ele- gans, 550 ; Gebhardi, 559* ; Hu- ronensis, 550 Aporoxylon, 627 Aporrhais occidentalis, 984 ; Sower- byi, 925 Appalachian Chain, 24, 389, 559, 734, 743, 798, 799 coal-field, 648 flexures, 102*, 353, 354, 355*, 356* geosyncline, 357, 537, 570, 605, 629, 715 Mountain Range, 389 ; character- istics of, 353-357 Mountain System, 389, 732, 883 Mountains, making of, 357, 387, 631, 728, 729, 736 Appalachian protaxis, 24, 443*, 444, 450, 461, 464, 466, 467, 483, 490, 524, 740 revolution, 728, 735, 877 Appomattox formation, 965 group, 892 Apteryx, 54, 1014 Aptian group, 859, 865 Aptychus beds, 791 Apuan Alps, fossils of, 310 Apus, 486 Aquamarine, 67 Aquitanian group, 884, 926 Arachnids, 418, 419, 420, 721, 722 ; derivation, 722-723 ; relations in body segments and limbs to Crustaceans, Limuloids, and In- sects, 724 , Upper Silurian, 557, 574, 721 ; Carboniferous, 677, 678*, 691, 703; Paleozoic, 721; Tertiary, 901, 922 Arachnophyllum, 552 Aragonite, 69, 129, 130, 314, 317 Aral Sea, 22, 33 Aralia, 831, 837 Aralo-Caspian depression, 22, 23 Arapahoe beds, 827 Ararat (Mt.), 296 (height) Araucarites, 750, 777 Arbor vitas, 435 Area, 855, 916; crassicosta, 900*, 917; idonea, 917; incilis, 917; inornata, 916 ; Mississippiensis, 898*, 916 ; scalarina, 917 ; subros- trata, 917 Arcestes, 756, 757 ; cirratus, 757 ; Gabbi, 757, 758 ; giganto-galeatus, 774 ; Nevadensis, 757 ; ruber, 774 Archaean, 440 ; iron ores in, 376, 449 Eozoon, 319 map of N. America, 442, 443* origin of later rocks, 458 protaxes of N. America, 359, 393, 457, 531, 744, 746, 812, 826, 875 ranges of the Atlantic border, 461 system of mountains in eastern N. America, 389 of the Rocky Mountain Chain, and of the Front Range of Colo- rado, 389 Archaean time, 204, 311, 326, 368, 380, 384, 387, 389, 393, 404, 407, 409*, 410, 440-459; N. America, 442 ; foreign, 456 ; observation's, 457 ; age of, in eastern America, 466 Archaelurus, 918 Archaaocalamites radiatus, 596* Archa?ocidaris, 641, 674, 707; Nor- woodi, 640*, 646 ; Shumardana, 626 ; Wortheni, 640*, 646 Archaeocyathus profundus, 470* Archaaoniscus Brodiei, 783* Archaeophyton Newberrianum, 454 Archaaoplax signifera, 917 Archseopteris, 596, 639, 699 ; Bock- schiana, 645; Browni, 622; Gas- piensis, 611 ; Halliana, 609*, 622 ; Hibernica, 626; Jacksoni, 595*, 1042 INDEX. 622 ; minor, 609*, 645 ; obtusa, 645; Kcemeriana, 704; Kogersi, 622 Archaeopteryx, 795 ; macrura, 788* Archseoptilus ingens, 702 Archaeoscyphia Minganensis, 497* Archeozoic scon, 407, 441, 442, 453 Archegosaurus Decheni, 708 ; minor, 703 Archidesmus MacNicoli, 625 Archimedes, 641 ; Wortheni, 642*, 646 Archimedes limestones, 637, 646 Archimylacris, 691 Architarbus, 701 ; rotundatus, 691 ; subovalis, 703 Architectonica, 916 Archiulus, 691, 701 ; Dawsoni, 691 ; euphoberioides, 691 ; Lyelli, 691 Archypterygian, 725 Arcoptera aviculaeformis, 900*, 917 Arctia, 723 Arctic bathymetric map, 950 Arctic border of N. Amer., 864, 739 emigrant plants of the Glacial period still surviving, 945 Ocean, 31, 43, 359, 814, 819, 827, 857 pole, 17 regions, climate of, 256, 524, 792, 793, 1026 , Archaean in, 442 ; Carbonife- rous, 606, 635, 659, 663, 689, 696, 704, 711; Cretaceous, 813, 818, 868, 877, 939 ; Devonian, 606 ; Ju- rassic, 749, 760, 792, 794 ; Lower Helderberg, 559 ; Lower Silurian, 490, 495, 524; Mesozoic, 793; post-Mesozoic, 874 ; Niagara, 541, 544 ; Paleozoic, 793 ; Subcarbo- niferous, 640, 696 ; Tertiary, 880, 933, 939 (plants) ; Triassic, 792 ; Upper Silurian, 544, 552, 571 Arctocyon, 925 Arctomys, 919 Arctosaurus Osborni, 749, 792 Arctotherium simum, 1000 Ardea herodias, 767 Ardennes, 626, 696, 734 Areia, 521 Arenaceous rocks, 490, 491, 495, 515 ; shale, 468 Arenaria glabra, 946; Grb'nlandica, 946 Arenicola, 423 ; marina, 420*, 423 Arenicolites, 446, 482 Arenig group, 517, 518, 520 Arequipa Mt., 274, 296 Arethusina, 521 Argentine Cordillera, Cretaceous in, 867 Republic, Cambrian in, 483 Arges armatus, 627* Argillaceous rocks, 78 Argillyte, 80, 84, 89, 371, 408, 531, 659 Argonaut, 424 Argovian, 790 Argyrocetus, 927 Argyrosaurus, 867 Arica, earthquake at, 213 Arionellus, 482 Aristolochia, 896 Aristozoe rotundata, 474* Arizona, 23 (height), 135 (agatized wood), 187, 300, 541 , Archaean in, 449 ; Cambrian, 466, 469, 477, 484; Upper Silu- rian, 541 ; Devonian, 581 ; Carbo- niferous, 469, 658, 674; Sub- carboniferous, 469 ; Permian, 660 ; Jurassic, 747 ; Tertiary, 937 (erup- tions) Arkansas Hot Springs, water of, analyzed, 121; lead mines, 842, 522 ; novaculite, 80 Canon, 495 Arkose, 82, 741 Armadillo, 54, 1002 Armorican sandstone, 521 Arnioceras Humboldti, 760 ; Neva- dense, 760; Nevaduum, 759*; Woodhulli, 760 Arniotites Vancouverensis, 758 Arsenopyrite, 70 Artesian borings (wells), 120, 207*, 257, 522, 742, 889, 890 Arthroclema Billingsi, 506*; cor- nutum, 506* Arthrolycosa antiqua, 678*, 691 Arthrophycus Harlani, 549 Arthropods, 141, 419, 423, 455, 469 Articulates, 141, 409*, 418, 419, 420*, 437, 439, 674, 7lt, 720, 783* Artiodactyls, 906, 907, 909, 910, 911*, 918, 919, 924, 927, 928, 930 Artisia, 673 Artocarpus Lessigiana, 839 Arum family, 777 Arvonian period, 446, 457 Asaphus, 422, 482, 488, 500, 502, 508, 516, 521, 551 ; Canadensis, 516, canalis, 503, 517; Homfrayi, 520 ; marginalis, 503 ; megistos, 422, 512, 551 ; obtusus, 503 ; platy- cephalus, 422, 508*, 512, 515, 516 ; Powisi, 519, 520*; tyrannus, 520 Asbestos, 67, 319 Ascension Island, volcano of, 290, 297 Ascidians, 55, 418, 725 Ascoceras, 551; Canadense, 573; Newberryi, 551, 573 Ash beds, 80 of coal, 661, 662, 663, 664 of plants, 73, 74, 75 ; see also Volcanic ashes Ashley beds (marl), 888, 891, 917 Asia (see also Eurasia), 19, 22, 23, 24, 31, 32*, 33, 34, 40, 41, 50, 165, 393, 394, 395, 398, 406, 737, 871, 938 , Carboniferous in, 632, 693, 700 ; Lower Silurian, 521 ; Upper Silurian, 563 ; Triassic, 632, 741 ; Cretaceous, 867; Tertiary, 365, 919, 933, 936, 939; Quaternary, 950 , eastern, island chains, 40 Asia Minor, 296 (volcanoes), 920 (Eocene) Aso-san (Mt.), 277 Asphalt, 74 Aspidella Terra-novica, 446 Aspidium Dunkeri, 831; filix, 74; Lakesii. 839 Aspidoceras, 794 Aspidorhynchus, 784* Asplenium erosum, 889 ; filix, 74 Ass, 55 Assat Lake, 200 Astacus, 783 Astarte, 780 ; annosa, 837 ; Banksii, 983, 984 ; borealis, 984, 995 ; com- pressa, 791; elliptica, 983 ; gre- garia, 790 ; Laurentiana, 984 ; minima, 780*, 790 ; obliqua, 790 ; obovata, 867 ; protracta, 916 ; Smithvillensis, 916; supracoral- lina, 790 ; undulata, 917 ; veta, 837; vicina, 917 Astartian group, 790 Asterias arenicola, 994 Asterioids, 428, 429* ; Lower Silu- rian, number in Great Britain, 521 Asterochlsena Noveboracensis, 610 Asterolepids, 417 Asterolepis, 625, 626, 627 Asterophyllites, 639, 671, 699, 704 ; acicularis, 622 ; elegans, 699 ; equisetiformis, 645, 671*, 689 ; foliosus, 689; latifolius, 596*, 622 ; sublams, 671*, 689 Asteropteris Noveboracensis, 610 Asthenodon segnis, 767* Astian group, 927 Astoria, Oregon, sandstone veins, 344* ; sandstones and shales, 892 Astoria clay-shales in Washington, 892 Astraea distorta, 791 Astraeospongia, 550, 584, 590 ; men- iscus, 550 Astral aeon, 440 Astraspis desiderata, 509* Astrocerium venustum, 550 Astrocoenia, 777, 778 (number of British) Astrodon Johnstonii, 836 Astylospongia, 515, 550; parvula, 513 ; Eoemeri, 503 Asymptoceras capax, 691; Newtoni, 691 Atacarna desert, 51 Atacamite, 335 Atane group, 831, 837, 838, 839, 872 Atanekerdluk series, 921 Athabasca Lake, 29 Athrodon, 789* Athyris, 642 ; angelica, 592, 621 ; concentrica, 426*, 626, 627 ; la- mellosa, 700* ; spiriferoides, 598*, 601 ; subtilita, 675*, 685, 704, 711 Atiu Island, elevation, 350 Atlantic City boring, 378 coast of N. Amer., 948 (fiords) ; subsidence in progress, 350 division of Archaean rocks, 446 Ocean, 17, 19 (depth), 20, 21, 31, 34, 40, 42, 43, 46 (temperature), 47*, 48, 49, 121 (salinity), 230 (bottom), 252, 256, 354, 391, 394, 536, 587, 793 ; volcanoes in, 297 , currents, 43, 44, 45, 46, 47*, 48, 256 and Pacific in Lower Cretace- ous united over Mexico, 814, 818 Atlantis, 506 INDEX. 1043 Atlantis of fable, 20, 217 Atlantochelys Mortoni, 849 Atlantosaurus immanis, 764 Atlantosaurus beds, 748, 758, 760, 761, 766, 767, 768, 776 Atlas Mts., 33 Atmosphere, 63 ; currents of, 49 ; weight of, 158 as a mechanical agent, 118, 158- 165 , carbonic acid in, 128, 727 , estimated limit, 16, 158 ; varia- tions in density, 256 of the Carbonic era, 711 ; Paleo- zoic, 727 Atmospheric dust, 118 Atolls, 145*, 146, 147, 148, 149*, 150, 151, 221, 227, 350, 664 Atractites, 757 ; secundus, 774 Atretia, 59 Atrypa, 436*, 520, 552, 562, 612 ; aspera, 590, 591, 598*, 601, 602, 625; comata, 568; desquamata, 628; hemisphserica, 550; hystrix, 613* ; imbricata, 520 ; .impressa, 590 ; laevis, 625 ; navicula, 568 ; no- dostriata, 548*, 551 ; oblata, 549 ; occidentals, 590 ; reticularis, 426*, 522, 546*, 550, 551, 552, 562, 567, 568, 569, 572, 590, 591, 592, 598*, 601, 602, 612, 620, 625, 626, 627, 628 ; rugosa, 551 Atrypina disparilis, 548*, 551 Aturia ziczac, 925 Aublysodon, 856 ; mirandus, 856 Aubrey limestone, 658; sandstone, 658 Aucella, 748, 749, 760, 794, 809, 818, 834, 835, 837 ; Erringtoni, 759* ; gryphaeoides, 865 ; Piochii, &34, 835* Aucella beds, 748, 776 Auchenapsis, 625 Auchenia major, 1001 ; minor, 1001 Auckland Islands, 37 Augite, 67*, 85, 86, 87, 88, 295, 324 andesyte, 87, 265, 324 dioryte, 86, 266 granite, 85 quartz-syenyte, 85 syenyte, 85, 317 Augitic rocks, 89, 309, 371, 449 Augitophyric, 77 Aulacoceras Carlottensis, 758 Aulopora, 550, 562, 621 ; precia, 550 ; repens, 550 ; tubiformis, 628 Auriferous belt, of the Sierra, 809 Aurochs, 927, 1006 Auroral group of Kogers, 490, 728 Austin limestone, 815, 817, 824, 855 Austin-Dallas chalk, 824 Australasian chain of islands, 37, 38, 39*, 40 Australia, 17, 19. 21, 22, 34 (system of reliefs), 39, 51, 53 (animal char- acteristics), 148 & 151 (reefs), 153, 346 (sea level at center), 394, 395, 398, 406, 415, 418, 687, 715, 797, 798, 838, 869, 874 (con- nection with S. A'frica), 921, 948 (fiords) ; related in species of birds to New Zealand, 1019 Australia, Cambrian in, 483 ; Lower Silurian, 522 ; Upper Silurian, 563, 564; Devonian, 628; Carbonic, 632, 693 ; Permian, 632, 698, 737 ; Triassic, 632, 699, 791, 797-798* ; Jurassic, 699, 770, 776, 791, 792; Cretaceous, 887; Tertiary, 937; Glacial, 948 Australian Alps, 34, 380 types in Europe, 922, 939 Austria, Upper Silurian in, 573; Subcarboniferous, 698 ; Carbon- iferous, 693, 696; Permian, 698; Triassic, 755, 768, 769 ; Jurassic, 774; Cretaceous, 857, 859, 864; Tertiary, 926, 927 Austro-Russian Cretaceous basin, 857 Auvergne, 26, 274, 297 (volcanoes), 922, 938 (eruptions) Aux vases sandstone, 638 Avalanche, 233, 247 Avalon, 446 Avicula, 525, 549, 585, 756, 916; contorta, 770, 771*, 774 ; demissa, 511*, 516; echinata, 791; emace- rata, 548*, 550, 551 ; exilis, 774 ; expansa, 790 ; Homfrayi, 757 ; insequivalvis, 790 ; Kazanensis, 707 ; linguiformis, 855 ; longa, 690 ; Munsteri, 791 ; naviformis, 562; obscura, 558; ovalis, 790; rhomboidea, 546*, 550 Avicula contorta beds, 769 Avicula family, 840 Aviculoides labiatus, 855 Aviculopecten, 562, 602, 620, 621 ; altus, 757, ; amplus, 647 ; Burling- tonensis, 647 ; duplicatus, 613*, 621 ; Idahoensis, 757 ; oblongus, 647 ; Oweni, 647 ; Pealsi, 757 ; princeps, 602 ; rectilaterarius, 690 Axinaea, 916 Axinite, 310 Axinus angulatus, 925 Aymestry limestone, 563, 567, 568 Azof Sea, 857 Azoic, 440, 468 Azores, 41, 297 (volcanoes), 308 (geysers) Bacillaria paradoxa, 437* Bacteria, 52, 136-137, 436, 441, 454 Bactrites, 621 ; acicula, 613*, 621 ; clavus, 599 ; gracilis, 627 Baculites, 843, 856 ; anceps, 854, 855, 867; annulatus, 855; asper, 855; Chicoensis, 831; compressus, 842*, 843, 854, 855 ; Faujasi, 866 ; grandis, 855; ovatus, 842*, 854, 855; Spillmani, 855; Tippoensis, 855. Bad Lands, 893, 894 Badiotites, 757 ; Carlottensis, 758 Baffin Bay, 40, 44, 252 (icebergs), 444 Land, 444 Bagshot beds (sands), 920, 925, 926 Bahamas, 162, 163, 213 Bahian group, 867 Bahio Glacier, 240 Baiera, 685, 693, 750 ; digitata, 705 ; longifolia, 833 ; Virginiana, 705 Baikal (.Lake), 33, 200 Bajocian group, 775, 790 Baker (Mt.), 296 (height) Island, changes in position of beach, 225* Bakewellia antiqua, 707 ; parva, 685* Bala group, 517, 518, 520, 569 ; lime- stone, 519 Bala?na, 144 Batenoptera, 144 Balatonites Vancouverensis, 758 Bald Mt., 467, 473, 495, 496, 527, 528* Baleen Whales, 912, 925 Balkan peninsula, 793 Ball ore, 664 Ballston Springs, analysis, 121 Baltic provinces, 768, 794 Sea, 41, 121 (salinity) Baluchistan earthquake, 375 Bandai-san eruption, 293 Banks Land, 635 Baphetes planiceps, 682, 692 Baptanodon beds, 748, 758, 760 Baptanodon discus, 761* Baptoruis, 852 Baptosaurus fraternus, 848 ; platy- sphondylus, 848 Baraboo quartzyte, 468 Barbados, 163, 433, 935, 936 Barbatia parva Missouriensis, 836 Baring Isl., 659 Barite, 69, 143, 331, 333, 342, 493, 745 Barium sulphate. See Barite Bark, composition of, 713 Barnacles, 157, 421 , 513 ; Cornifer- ous, 586, 587; Hamilton, 600*; Lower Silurian, 496, 720 ; Paleo- zoic, 720 Baropus lentus, 684* Barornis regens, 902 Barrandia, 520, 521 Barren (Lower) Measures, 634, 648, 651-652, 656, 657, 677 Barren (Upper) Measures, 634, 648, 651, 657, 660 See also Permian period Barrier reefs, 14S*, 149*, 150*, 151, 227, 541, 713 Barriers, sand, of coasts, 223, 224* Barrow (Point), 640 Barrow Strait, 544, 552 Barton clay (series), 925/926 coal-bed", 652 Bartonian group, 925 Barycrinus, 138 Baryta, Barytes, 69 Basalt, 16, 67, 87, 134, 259, 288* | Basaltic columns, 261*, 262*, 263, 274 Basement Complex, 458 Basic igneous rocks, 64, 65, 86, 273, 938 Basilosaurus, 908 Bat. See Bats Bat guano, 153 Bath Oolyte. See Oolyte Bathonian group, 775, 790 1044 INDEX. Bathurst, N.B.,350 Land, 659, 749, 792 Bathyactis symmetrica, 57 Bathycrinus, 59 Bathygnathus borealis, 741, 753, 754* Bathylite, bathylith, 811 , 938 Bathymetric map of the Pacific and Atlantic, following. 20 of the Arctic Ocean, 950 of the Atlantic border of New Jersey, Long Island, etc., 18 Bathynoinus giganteus, 59 Bathynotus holopyga, 473* Bathyopsis, 918 Bathyurellus, 500, 503 ; nitidus, 501* Bathyuriscus Howelli, 476* Bathyurus, 500 ; Angelini, 503, 517 ; arinatus, 501 ; conicus, 517 ; cro- talifrons, 501* ; extans, 517 ; Saf- fordi, 501*, 517 Batocrinus, 641, 646 ; Christyi, 640*, 646 ; longirostris, 428*, 430, 640*, 646 Batodon tenuis, 853* Bats, 53, 54, 153, 415, 721, 797, 907, 910, 924, 926 Batscham, tide at, 211 Bavaria, 26, 453 , Archaean in, 453, 454, 456 ; Cre- taceous, 857 ; Jurassic, 774, 776 Bay of Biscay, 377 of Fundy, 210 (tides), 350, 444, 461, 536, 741 of Plenty, 374 Beach formations, 94, 95, 151, 202, 222, 223 ; structure, 93, 99, 222 Bear Island, 635, 704 Kiver coal-beds, 825, 839 Beauchamp sands, 925 Beaufort beds, 699, 707, 770 Beaver Kiver, 947 Beavers, 55, 904, 911, 927, 950 (mi- gration) Becrafts Mt., 531, 552, 558, 559, 577, 578, 579 Beds, 76, 91, 92 (kinds) of ore. See Ore-beds of sand, mud, limestone, etc., simultaneously in progress, 399 Beech, 812, 837, 922 Beehive Geyser, 307*, 308* Beemerville rock, 532 Beetles, 419, 679, 702, 721, 722, 771, 887 Beggiatoa, 137 Bela exarata, 984; harpularia, 984; robusta, 984 ; turricula, 984 Belcher Expedition, 792 Belemnitella Americana, 842*, 854 ; bulbosa, 855; mucronata, 855, 866 ; plena, 866 ; quadrata, 866 Belemnites appressus, 835; cana- liculatus, 791 ; clavatus, 790, 791 ; densus, 758*, 760 ; hastatus, 790 ; jaculum, 865; Nevadensis, 760; niger, 760 ; Oweni, 790 ; Paciflcus, 760; paxillosus, 760, 782*, 790; vulgaris, 790 Belemnoteuthis, 782; antiqua, 782* Belgium, Carboniferous in, 693, 696, 768; Cretaceous, 848, 859, 863; Paleozoic, 463 ; Tertiary, 920, 921, 925, 926 ; Upper Silurian, 568, 569 Belinurus, 701, 720 ; arcuatus, 703 ; Reginse, 703 ; trilobitoides, 703 Belle Isle, 467 ; Strait of, 793, 873 Bellerophon antiquatus, 478* ; bilo- batus, 507*, 514, 520, 521, 550, 569 ; Cambrensis, 481 ; carbonarius, 675*, 690 ; carinatus, 520, 567, 573 ; cyrtolites, 647; dilatatus, 567; expansus, 573 ; maera, 592, 613* ; natator, 620 ; nodosus, 520 ; patu- lus, 602; trilobatus, 567; Urii, 690, 711 Bellerophon limestone, 660 Bell's Landing beds, 888 Belly Kiver group, 830 ; region, 825 (coal), 880 Belodon, 754, 758; Carolinensis, 754*; priscus, 754* Belodonts, 772, 773 Belceil Mt., 531 Belosepia sepioidea, 925; ungula, 897*, 916 Beluga Vermontana, 983 Bembridge beds, 926 Beneckia Buchii, 773 Bengal coal-beds, 698 Benton group, 815, 829, 850 Benzine, 74 Berea grit, 608 Bergkalk, 632 Bering Sea, 43 ; Strait, 43, 48, 257, 877, 950 (dry ?) Bermuda Islands, 20, 46, 145, 162, 218, 224 Bernardston, Mass., 310, 825 Bernician group, 695 Beryl, 67, 69, 332, 336 Beryllia, 67 Beryx, 862 ; insculptus, 843 Besano dolomyte, 774 Betulji, 840 Beverly Island, 39 Beyrichia, 516, 562, 567, 643 ; bella, 515 ;1ata, 562 ; spinosa, 550 ; sym- metrica, 549*, 550; trisulcata, 558; tuberculata, 568 Big Cotton wood Canon, 476, 495 Horn basin, 893, 906 Horn Mts., 266, 478, 748, 830 Billingsella festinata, 471*; gran- dseva, 499*, 500 ; orientalis, 471* Bilobites, 474, 546 ; bilobus, 551 Biotite, 65, 83, 85, 86, 87, 318, 320 gneiss, 83 ; granites, 82 ; mica, 320 Birch, 837 Bird of paradise, 54 Birds, 141, 163, 414, 415, 721, 752, 786, 789, 794, 795, 796, 877, 879, 914 , Triassic, 794 ; Jurassic, 767, 776, 783, 788*, 795, 796, 852, 871 ; Cre- taceous, 812, 850*, 851*, 852, 864, 870, 871 ; Tertiary, 883, 893, 902, 921, 923, 925 Birdseye limestone, 489, 492, 493, 494, 503, 505, 515 Bismuth, 331 Bison Americanus, 1001 ; antiquus, 1002, crassicornis, 1002; latifrons, 999 ; priscus, 1015 Bitter Creek group, 886 Bittern, 120 Bittium Chipolanum, 917 Bitumen, 337, 581, 593 Bituminous coal, 74, 124, 649, 655*, 661, 695, 714, 731, 741, 825 ; analy- ses, 485, 662, 6C8, 664, 712, 713 Black Bluff beds, 888 Black Dome, 27 Forest, 698, 734 Hills, 830; Archaean in, 444; Cambrian, 469; Niagara, 541, 543; Carboniferous, 658; Trias- sic, 746, 747 ; Jurassic, 747, 748, 758, 760; Cretaceous, 818, 827, 829, 832, 843 Black lead, 62 Black River limestone, 489, 492, 494, 503, 506, 513, 514, 515 Black Sea, 22, 857 Blackfoot Basin, 747 Blake plateau, 230 Blanching of rocks, etc., 134, 822 Blanco group, 884, 885, 895, 912, 919 Blastoidocrinus carcharidens, 503 Blastoids, 430, 547*, 548 (first), 585* 590, 641, 646 Blastomeryx, 911, 919 Blattariaa, 757 Bleaching. See Blanching Blende, 70, 333, 493 Block coal, 661, 662 Block Island, 852 Blood rains, 163, 165 Bloomsbury conglomerate, 594 Blowing-cone, 279, 284 Blue limestone of Owen, 494, 516, 728 or Maclurea limestone of Safford, 494 Blue Mts., Australia, 34 Blue Mts., N.J., 532 Blue Mts., Oregon, 748, 749, 811, ' 830 Blue Ridge, 468, 745 Bluestone, 593 Boa constrictor, 156 Boavus, 901 Bob, Mt., 552, 558 Bodie Mt., auriferous veins of, 334 Bog-head cannel, 662 Bog ore, 128, 129, 708 Bohemia, upturnings in, 630, 734 , Archaean in, 455, 456 ; Cambrian, 482, 518; Lower Silurian, 518, 521 ; Upper Silurian, 563 ; Car- boniferous, 696, 703, 723; Trias- sic, 768; Cretaceous, 838; Ter- tiary, 938 (eruptions) Bohemian formation, 535 Bohemilla, 521 Bolderian beds, 926 Bolivia, 26 (plateau), 41, 296 (volca- noes), 627, 628, 711 Bolodon, 789* Bolonian, 791 Bombay, 299 Bombs, volcanic, 287*, 289 Bone-beds, Quaternary, 892 ; Ter- INDEX. 1045 tiary, 902; Triassic, 769, 774; Upper Silurian, 563 Bones, 63, 72, 73 (analyses), 141, 143, 144, 153, 162, 190 Bonneville Lake, G. K. Gilbert on, 202, 382 Bony coal-bed, 656 Boothia Felix, 495 Boracic acid, 63, 66, 813 Boracite, 320 Borate springs, 313 Borates, 119, 137, 320 Borax, 63 Lake, siliceous deposits, 323, 334, 335 Boring animals, 157, 425 Borneo, 40, 297, 696 Bornia inornata, 610; transitionis, 699 Bornite, 335, 745 Boron, 63, 320, 335 ; salts, 320 Borophagus, 919 Borsonia biconica, 916 Bos, 927 ; Americanus, 1016 ; pri- migenius, 1006, 1016 ; Urus, 1016 Boston basin, 732 Bothriolabis, 918 Bothriolepis, 616*, 617, 619, 625; Canadensis, 616*, 617 ; minor, 621 ; nitida, 621 Botryoconus, 689 ; Pitcairnise, 673*, 674 ; priscus, 673*, 674 Bottom-lands, 181 Bourbon, Isle of, 296 (volcanoes) Bourbonne-les-Bains, thermal wa- ters at, 335 Bourgogne, 769 Bow River region, 826 (coal) Bowlder clay, 81, 251 Bowlders, 81, 127*, 664 (in coal) ; see Glacier Drift. Brachiates (Brachiate Crinoids), 429 Brachiopods, 59, 60, 425*, 426*, 427* ; articulate and inarticulate, 425, 471 Brachiospongia, 515 ; digitata, 504*, 513 ; Roemerana, 513 Brachymetopus, 676, 700 Brachypsalis, 919 Brachyurans, 59, 420, 438439, 707, 720 Bracklesham beds, 923 Bradfordian, 790 Branchiates, 419 Branchiosaurus, 706 Branchiostoma, 418 Branchville granitic veins, 326 Brandon, Vt., lignite bed, 887, 895 Brandschiefer, 80 Brazil, 31 (mountains), 184; Archaean in, 456; Carboniferous, 659, 687; Devonian, 627 ; Jurassic, 776 ; Cretaceous, 857, 858, 867 Breaks in the geological record, 406, 488 Breccia, 80 Brecciated vein, 330 Brick-clay, 81 Bricks from the depths of the Atlantic, 230 Bridgeman's Island, 296 (volcanoes) Bridger group (beds), 884, 886, 893, 901, 904, 905, 907, 918, 923, 925 Lake (basin), 882, 893 Brier Hill coal, 657, 662 Brine springs, 120 Brines. See Salt British Channel, 16, 210, 936 Columbia, 25, 389, 390, 812, 948 (fiords); Cambrian, 476, 477; Carboniferous, 659, 674 ; Triassic, 746, 757 ; Triassic and Jurassic, 739, 809; Cretaceous, 818, 868; Glacial, 945, 948 ; Quaternary, 950 Brittany united with Cornwall, 936 Broad Top, 649, 659 Bromides, 63, 335, 341 Bromine, 63, 120, 331 Bromo-chloride, 340 Bronteus, 552, 561, 562, 568, 599, 625, 626 ; grandis, 627 ; pompilius, 561* ; Tullius, 599 Brontops, 918 ; robustus, 909* Brontosaurus excelsus, 763* Brontotherium, 914*, 918 Brontotherium beds, 886 Brontozoum giganteum, 752* Bronzite, 67, 136 Brooklyn, N.Y., water supply of, 206 Brookville coal, 652 Brown coal, 74, 662, 712, 713, 714, 920, 922 Brown's Park group, 886 Brownstone, 746 Brunswick, 769 Bryozoans, 141, 142, 147, 418, 419, 425*, 427* Bubo leptosteus, 902 Bucania, 503, 521, 562; rotundata, 502* ; sulcata, 503 ; trilobata, 544*, 549,550 Buccinum Groenlandicum, 984, 995 ; undatum, 984 Buchiceras inaequiplicatum, 837 ; pedernale, 836 ; Swallovi, 854 Buck Mountain coal-bed, 656 Buckingham (Va.) Triassic area, 741 Buckler, 421 Buff limestone, 494 Buhrstone, 82, 885, 888, 889, 890 Bulimus ellipticus, 926 Bulk, changes of, in mineral changes, 134, 138, 453, 523 Bulla, 916 ; speciosa, 841* Bullinella Jacksonensis, 916 Bumelia, 922 Bunselurus, 918 Bunker Hill Monument, 260 Buntersandstein, 411, 738, 769 Buprestids, 771 Buprestis, 783* (wing-case) Burdigalian group, 926 Burlington group, 634, 637, 638 limestone, 646 (Crinoids), 647 Burnetan, 446 Busycon Bairdii, 855 Buthotrephis, 544; gracilis, 504*, 549 ; Harknessi, 519* ; ramosa, 549 ; succulens, 504* Butterflies, 54, 419, 679; Tertiary, 202, 887, 900* Byam Martin Isl., 659 Byssoarca protracta, 916 Byssus, 424 Cadaliosaurus, 706 Cadent series, 728 Cadomella, 790 ; Moorei, 779* Cadulus turgidus, 915 Caenopus, 918 Caerfai group, 481 Caesium, 335, 449 Cahaba coal-fields, 657 Cainozoic. See Cenozoic Caithness flags, 623 Caking coal, 661, 662 (analyses) Calabria, earthquake in 1783, 375 Calais united with England, 936 Calamary, 424* Calamine, 342 Calamites, 627, 629, 671, 699, 704, 718; approximate, 654, 689; arenaceus, 774 ; cannaeformis, 622, 671*, 689 ; Cistii, 689 ; radi- atus, 622, 626, 704; ramosus, 689 ; Suckovi, 645, 654, 685, 689, 692, 704 Calamitids, 689 Calamodendron, 699, 718 Calamodon, 917, 918 Calamopora spongites, 310 Calamopsis Danse, 895*, 896 Calamus, 435 Calaveras skull, 1012 Calcaire carbonifere, 632 conchy lien, 769 grossier, 205, 884, 920, 923, 924, 925, 926 Calcareous deposits, 131, 132*, 133, 152-153; fossils, 129, 130, 314; organic rock-material, 72, 134, 140, 144, 487, 496 ; rocks, 78-80 ; sponges, 431 waters, 305 ; consolidation by, 133 Calceocrinus Barrandei, 514 Calceola sandalina, 427*, 626, 627 Calceola slates, 626, 627 Calciferous epoch, 490, 491 limestone group, 695 sandrock, 45*, 490, 500 Calcispongiae, 431 Calcite, 15 (density), 68* Calcium, 61, 67; bicarbonate, 122, 129 ; borate, 120 ; carbonate, 62 ; chloride, 119, 120; fluoride, 73, 121 (see also Fluorite) ; iodide, 120 : calcium-magnesium carbon- ate (see Dolomite) ; nitrate, 137 ; phosphate, 63 (Apatite); sul- phate, 72, 73 ; sulphide, 125 Calcyte, 79, 316, 321, 490; con- verted to dolomyte with dimin- ished bulk, 134, 523 California, 18, 23 (height), 25,29; silicified forests of, 135; Diatom bed, 152 ; Salton Lake, 200 ; vol- canoes of, 296 ; Table Mtn., 300 ; Borax Lake, 323 , Archaean in, 444 ; Silurian, 809 ; Devonian, 580, 592 ; Carbonifer- ous, 659, 674 ; Triassic, 746, 757, 809, 810 ; Jura-Trias, 749 ; Juras- sic, 748, 749, 759, 760, 809; 1046 INDEX. Cretaceous, 317, 318, 325, 811, 818, 820, 830, 834, 837, 840, 868 (subsidence) ; Tertiary, 831, 884, 885, 888, 891, 892, 895, 916, 932, 937 ; Glacial, 949 ; Quaternary, 950 Caligus, 420 Callipteridium, 685, 693, 699 Callipteris, 685, 693, 699; conferta, 704 ; pilosa, 622 Callitris, 922 Callocystites Jewetti, 429*, 547, 550 Callovian group, 760, 775, 776, 780, 790 Caloosahatchie beds, 890 River, 892 Calophyllum, 552 Calopodus, 692 Calumet mine, 339 Calvert Cliffs, 891 Calymene, 810, 422, 520, 521, 546, 551 ; Allportiana, 520 ; Blumen- bachii, 420*, 421, 520, 551, 552, 562, 567, 568, 586; callicephala, 508*, 509, 512, 515, 524, 549, 550; Christyi, 516; Clintoni, 550; Niagarensis, 549, 550, 551; pla- tys, 591 (last American species) ; tuberculosa, 551, 567, 569 Calyptraea, 475 Camaphoria subtrigona, 646 Camarella antiquata, 471* ; calcifera, 500 ; congesta, 550 ; longirostris, 503 ; primordialis, 478* ; varians, 500,503 Camarocrinus Saffordi, 550; stel- latus, 558 Camarophoria, 707 (ends in Per- mian) ; crurnena, 707; formosa, 627; Humbletonensis,704; Schlot- heimi, 707 ; superstes, 707 Cambrian and Silurian, history of the terms, 463, 464, 489 Cambrian, 462; American, 464; foreign, 480 Cambric. See Cambrian Cambridge Greensand, 863, 864 Camel, 54, 55, 907, 910, 911, 912, 919, 928 Camelopardalis, 54, 927 Camelus, 927 Cameroons Mts., 295, 297 (height) Campanian, 859, 866 Campbell Island, 89 Campophyllum torquium, 690 Camptonectes bellistriatus, 760 Camptonyte, 87 Camptopteris, 756 Camptosaurus dispar, 764, 765*; medius, 765* Campylodiscus clypeus, 163, 164* Canada, 24, 26, 78, 258 , Archaean in, 443 ; Cambrian, 464, 466, 476, 479, 496; Calcifer- ous, 491, 492, 493, 496, 497, 499, 500, 501; Chazy, 491, 493, 503; Trenton, 493 ; Clinton, 542 ; Me- dina, 539, 542; Niagara, 540, 543, 544, 549, 551 ; Devonian, 576, 581, 591, 611, 628, 630; Corniferous, 580, 581, 590, 591 ; Carboniferous, 453, 581 ; Creta- ceous, 825, 830, 840, 872; Ter- tiary, 918 Canada Bay, 467 Canadian Pacific R.R., 26, 859 period, 491 River, 29 Canary Islands, 20, 41, 207 Cancer, 420* Cancrinite, 85, 449 Canimartes, 919 Canis, 911, 919, 927 ; Parisiensis, 924 Canistrocrinus, 516 Cannapora junciformis, 550 Cannel coal, 654, 661, 662 (analyses), 692, 710 (formation), 714 Cap au Gres, 732 Cape Breton, Cambrian in, 476 ; Carboniferous, 691 ; Coal-meas- ures, 658, 678 Cape Cod, 160, 873, 881, 916 Dundas, 659 Girardeau limestone, 559 Hatteras, 18, 43, 45, 48, 210, 224*, 793, 823, 878, 949 Horn, 21, 23, 858 of Good Hope, 21 Verd Islands, 297 Capelin, 984 Caprina, 820 ; adversa, 866 ; anguis, 886 ; Texana, 834, 835* Caprina limestone, 817, 886 Capulus, 471, 482, 574 Carabocrinus, 516 Caradoc group, 463, 518, 534 ; sand- stone, 520, 584 Carbon, 61, 62 ; Archaean, 453, 454 Ridge, 733 Carbonaceous clay, 81 rock-material, 74, 140, 141, 153- 155, 315 (metamorphic changes), 819,453 shale, 80 Carbonate of lime. See Calcite. of magnesia, 69 Carbonates, 68 Carbonic acid, 62, 128-185; in Archaean, 440, 441, 442, 450, 451, 454; in Cambrian atmosphere, 485; at beginning of Carbonic era, 711, 712 ; constructive effects, 181; destructive, 129; in geyser region, 309 ; from respiration, 136 ; from volcanoes, 128, 278 Carbonic era, 631 ; American, 633 ; foreign, 693; formation of coal, 712 ; economical products, 661- 665 Carbonic oxide, 278 (from Kil- auea), 523, 661 Carboniferous age, 631 Carboniferous period, 647 Carcharias, 863 Carcharodon, 144, 855 ; angustidens, 416*, 901*, 917, 926; megalodon, 901 Carcharopsis Wortheni, 644*, 647 Carcinosoma ingens, 557 Cardinia concinna, 790 ; Listeri, 790 Cardiocarpus, 435, 622, 674; bicus- pidatus, 673*, 689 ; bisectus, 678*, 689 ; elongatus, 673*, 689 ; samar- aeformis, 673*, 689 Cardioceras, 794 ; dubium, 760 Cardioceras family, 760 Cardiola, 621; retrostriata, 621, 627 ; speciosa, 620 Cardiomorpha Missouriensis, 690 Cardiopsis radiata, 647 Cardiopteris, 645; frondosa, 704; polymorpha, 704 Cardita, 916; planicosta, 926; sul- cata, 926 Carditatnera arata, 917 Cardites crenatus, 774 Cardium, 916 ; Dalli, 917 ; diversum, 916; dumosum, 854; Eufaulense, 854 ; Hatchetigbeense, 915 ; Hil- lanum, 865 ; Islandicum, 983, 984 ; laqueatum, 917; Purbeckense, 791 ; speciosum, 855 ; Virginia- num, 917 Carentonian, 859, 866 Caribbean Sea, 20, 44, 45, 49, 936 Caricella Claibornensis, 897*, 916; demissa, 916 ; doliata, 916 ; Leana, 915 Caridoids, 421 Carinaropsis, 482 Carmel (Mt.), Conn., 801*, 802, 807 Carmon, 521 Carnallite, 120 Carnic (Lower), 757 Carnivores, 902, 903, 910, 911, 918, 919, 924, 926, 927, 929, 930, 931 Caroline Archipelago, 38, 39, 145, 850 Carp River, unconformability at, 465*, 468 Carpathian Mts., 32, 41, 365, 774, 793, 812, 920 Carpinus, 896 Carpolithes Brandonensis, 896* ; irregularis, 895*, 896 Carrara, 309 Carrizo Creek, Cal., 892 Carson Lake, 811 Carterella, 432* Carya, 550, 896 Caryocrinus, 550; ornatus, 547*> 550,551 Caryoderma, 919 Caryophyllia, 860 Cascade Range, 25, 28, 29, 80, 40, 280, 296 (volcanoes), 300, 389, 739, 747, 811, 830, 831, 945 Cashaqua shale, 605 Caspian Sea, 22, 83, 49, 199, 200, 296, 768, 776, 857 Caspian steppes, 156 Cassia, 921 Cassidaria dubia, 916; Petersoni, 916 Cassidulus, 84; sequoreus, 855; florealis, 854 Cassiope hypnoides, 945 Cassowaries, 54 Castor Canadensis, 55, 1000 ; fiber, 55 Castoroides Ohioensis, 1000, 1012 Casuarina>, 922 Casuarius, 54 INDEX. 104T Catacecaumene region volcanoes, 296 Catarractes affinis, 1002 Catchfly, 945 Catlinite, 468 Catopterus gracilis, 751* Catopygus carinatus, 866 ; pusillus, 854 Catskill beds (group), 576, 602 Mts., 25, 188, 225, 357, 605, 636, 744, 745, 946 shaly limestone, 559 Caucasus, 41, 239, 265, 857, 920 Cauda-galli epoch, 410 grit, 558, 559, 576, 579, 581, 728 Caulerpit.es, 688 Caulinites sparganioides, 839 Caulopteris, 584, 699 ; ad vena, 584 ; antiqua, 583* ; elliptica, 705 ; gigantea, 705; Lockwoodi, 611, 622; microdiscus, 705; peltigera, 705 ; Wortheni, 645 Cave animals, 927, 940 Cavern formations, 324 Caverns, 379, 399, 695, 883 ; making of, 116, 130*, 324 (Hawaiian); filled with vein-material, 328, 334, 342, 343 ; nitrates in, 137 ; rivers in, 207 Cayambe Mt., 26 Cayuga Lake, 555, 559, 602, 603, 604, 605 ; jointed rocks, 112* Ceanothus, 921 Cebochaerus, 926 Celastrinites laevigatus, 839 Celastrus, 921 Celebes, 19, 40, 309 Celestite, 493, 540 Cement, 79, 80, 555 Cementing coal, 661 Cenomanian group, 815, 832, 857, 858, 859, 860, 865, 866 Cenozoic time, 879 Centipeds, 419 Central America, 40, 145, 296 (vol- canoes), 297, 338 Central Continental Interior. See Interior Continental Central Pacific E. K., 26 Centroceras, 602 Centronella, 579 Cephalaspids, 417, 625 Cephalaspis, 564, 566*, 587, 625; Campbelltonensis, 588* ; Daw- soni, 588*, 591; Lyelli, 624*; Murchisoni, 566, 567; ornata, 567 Cephalization, 414, 437-439 Cephalophora, 424 Cephalopods, 59, 130, 424, 425*, 501, 569 Ceram Island, 38 Ceratiocarids, 550, 721; Cambrian (Upper), 488; Chemung, 604; Hamilton, 599, 600* ; Lower Silu- rian, 521; Niagara epoch, 549; Upper Silurian, 574 Ceratiocaris, 482, 521, 546, 557, 565, 567; Angelini, 519, 520*, 549; Deweyi, 549, 550 ; papilio, 566* ; pusilla, 546 ; sinuata, 691 ; tenui- striata, 566* Ceratites, 757, 770, 771, 774; Malm- greni, 792; Middendorfi, 773; nodosus, 770, 771*, 774 Ceratodus, 59, 176, 417, 418, 687, 725, 772, 774, 797 ; culmination in Triassic, 869 ; Capensis, 770 ; favosus, 687 ; Guntheri, 760 Ceratolichas, 591 Ceratops, 856 Ceratops beds, 828, 845, 847, 849 Ceratopsidae, 846, 848 Ceratopsids, 828, 847, 856, 864, 870 Ceratosaurus nasicornis, 765, 766* Ceraurus (Cheirurus), 422, 482, 500, 502, 508, 513, 516, 520, 521, 546, 568, 625; bimucronatus, 520, 565*; Niagarensis, 550, 551; pleurexanthemus, 509*, 515 ; Satyrus, 503 ; Sternbergi, 568 Cerithiopsis, 916 Cerithium, 780, 854, 922 ; Austi- nense, 836; Claibornense, 916; concavum, 926 ; cymatophorum, 927 ; elegans, 926 ; Hillsboroense, 898*, 916; mutabile, 926; pli- catum, 926 ; variabile, 925 Cernaysian group, 884, 923, 925 Cerussite, 335 Cervalces Americanus, 999* Cervus, 927; anoceros, 927; Fal- coneri, 927 ; giganteus, 999, 1005 ; Muscatinensis, 966; Polignacus, 927 ; verticornis, 927 Cestracion, 60, 416*, 643 ; Philippi, 416*, 797 Cestracionts, 416*, 797, 869 (four modern) ; Corniferous, 589 ; Sub- carboniferous, 644, 647 ; Carbo- niferous, 680* ; Permian, 707 ; Triassic, 772; Cretaceous, 812, 843*, 863, 869 Cetaceans, 902, 912*, 925 Cetiosaurus, 786, 790 ; brevis, 863 ; Oxoniensis, 786 Cetotherium, 925 ; cephalus, 912* Chabazite, 68 Chsenohyus, 918 Chaeropotamus, 924 ; Cuvieri, 926 Chaetetes, 505 Chagos Islands, 737, 937 Chain coral. See Halysites Chalcedony, 323, 340, 859 Chalcedony Park, 135 Chalcocite, 385, 745 Chalcopyrite, 70, 331, 334, 335, 339, 340, 538, 542 Chaleur Bay, 444 Chalicotherium, 919, 925, 927 Chalk, 79, 205 (absorptiveness), 817 formation, 401, 407, 738 , Gray, Lower, Upper, White, 858 period, 738. See also Creta- ceous marl, 865, 866 Challenger Expedition, 49, 59, 144, 230, 241, 718, 823 Chama, 780, 834 ; crassa, 917 ; squamosa, 926 Chamaarops humilis, 58 Chamops segnis, 849 Chamouni, 233, 243, 246 Champlain (Lake), 200, 232, 467, 532, 558, 982* Champlain period, American, 981 ; subsidence, 981 ; foreign, 995 ; elevation at close of, 993 group of the Lower Silurian in New York, 489 Champsosaurus, 902 ; profundus, 856 ; Saponensis, 902 Chara, 72 (ash of), 582*, 590 ; fcetida, 72 ; Stantoni, 839 Charcoal, 62, 124, 662; mineral, 712 Charleston earthquake of 1886, 373, 374, 375 Chart. See Map Chasmops, 521 Chatham Islands, 39, 154, 1019 Chattahoochee group, 884, 890, 891, 898*, 916 River, 890, 891 Chaudiere River, 591 Chazy epoch, 493 Cheiracanthus, 625 Cheirurus. See Ceraurus Chelonians, 772, 787, 836, 849, 863 Cheltenham beds, 775 Chelys Blakei, 790 Chemical attraction as a dynamical agency, 117 changes producing heat, 258 products, mechanical work of, 137, 138* work, 118-140; solution, 118- 122 ; oxidation and deoxidation, 122-128; hydration, carbonic acid, humus acids, 128-135; sili- ca, 135-136 ; living organisms, 136-137 ; chemical products, 137- 139 ; concretionary consolidation, 139-140 of metamorphism. See Meta- morphism Chemnitzia, 781 ; gloriosa, 855 Chernung period, 602 Chenopus liratus, 916 Cherry Ridge group, 606 Chert, 63, 82 Chesapeake Bay, 744, 819, 889, 891 epoch, 884, 891 Chester group, 634, 637, 638, 639, 642, 645, 647, 709 Chestnut, 435, 837 Chetetes, 704 Cheyenne River, 266 Chiastolite, 65*, 66 Chico group (beds), 815, 818, 830, 831, 840, 889; see also Shasta- Chico series Chile, 137; snow-line in, 234; vol- canoes of, 296 ; earthquake in, 349 ; recent changes of level in, 349 ; Cretaceous in, 857, 867 Chilhowee sandstone, 468 Chilian Cordillera, 857 Chiloe, 23 Chilopoda, 419 Chimaera, 510 Chimerids, 416, 574, 725 Chimaeroids, Corniferous, 587, 589*; Cretaceous, 828 1048 INDEX. Chiraborazo (Mt.), 26, 274, 290, 296 China, 51, 84, 145; Cambrian in, 482 ; Lower Silurian, 522 ; Upper Silurian, 564; Devonian, 628; Carboniferous, 632, 693, 696 ; Cre- taceous, 833 China Sea, 92T Chinate Mts., 8T4 Chipola epoch (group), 884, 891, 899* 917 Chipola sands (fossiliferous), 890, 891 Chirolepis, 417, 620; Canadensis, 618* ; Trallii, 417* Chiropters, 918 Chirotherium, 772*, 773, 774 ; Eei- teri, 692 Chirox, 917 Chiton, 424 ; Canadensis, 514 ; car- bonarius, 690 Chlamydotherium, 1004 Chlorine, 63 Chlorite, 68, 89 argillyte, 89 rocks, 79, 83, 84, 86, 87, 819, 449 schist, 89 Chloritic marl, 865 Chlorophyll, 136 Cholaster peculiaris, 646 Cholodus, 692 Chomatodus, 692 Chondrites Colletti, 688 Chondrodite, 63, 67, 79, 319, 447, 449, 450, 531 Chondroditic limestone, 79, 449, 450,531 Chonetes, 546*, 550, 552, 562, 579, 611, 621, 622, 642, 674, 700 ; cor- nutus, 546*, 550 ; Dalmanianus, 703; deflectus, 592; Flemingi, 685; Hardrensis, 625, 628 ; hemisphae- ricus, 590, 592 ; Illinoisensis, 642*, 647; latus, 427* 567; lepidus, 612, 620 ; lineatus, 590 ; meso- lobus, 675*, 690 ; mucronatus, 592, 602; Novascoticus, 562; or- natus, 642*, 646 ; planumbonus, 646 ; scitulus, 612, 620 ; setigerus, 598*, 601, 620; striatellus, 567, 568 lophyllum Niagarense, 547*, Choristoceras, 771 ; Haueri, 774 Chouteau limestone, 637, 646 hrestotes Danae, 691 ; lapidea, 691 Christian ia, 309 Christianite, 186 Christmas Island, 151 (height) Chrome-spinel, 88 Chrysalidina gradata, 432*, 860* Chrysoberyl, 449 Chrysoeolla, 335 Chrysodomus Stonei, 917 Chrysolite, 67 Chrysolitie gabbro, 272; hornblen- dyte, 5:32 ; pyroxenyte, 582 rocks, 88-89 Chrysomelids, 771 Cicada, 419 Cidaris, 59, 641, 760, 779, 834, 840 ; Blumenbachii, 778*, 791; clavi- gera, 8664 erfitosa, 866; flori- gemma, 790, 791 ; splendens, 854 ; Texana, 837 ; vesiculosa, 866 Cimolestes incisus, 853* Cimoliosaurus, 845 Cimolos Island, 296 (volcanoes) Cincinnati, Ohio, 533 anticline. See Cincinnati uplift beds, 492, 504, 506, 511, 514, 515, 516 ; characteristic species, 516 epoch, 494, 559 group, 489 Island. See Cincinnati uplift uplift, 387, 490, 494, 522, 527, 532-533, 537, 539, 540, 633; in- fluence of, in the Upper Silurian, 571 Cinders, volcanic. See Volcanic Cinnabar, 335 Cinnabar, Mt., 829 Cinnamomum, 837, 896, 921 ; ellipti- cum, 839 ; Mississippiense, 895*, 896 ; Scheuchzeri, 839 Cinnamon, 921 Cinulia, 861; avellana, 861*; pul- chella, 854 Cirripeds, 420*, 421, 518 (earliest), 579, 720 Cladiscites tornatus, 771* Cladodus, 692, 702; Clarki, 619*, 620; Fyleri, 619*, 620; Kepleri, 620 ; marginatus, 702 ; sinuatus, 019*; spinosus, 644*, 647 Cladonia, 75; rangiferina, 75 Cladopora labiosa, 592 Cladoxylon mirabile, 621 Claiborne epoch (group), 884, 885, 889, 891, 916 (Lower), 884, 885, 888, 890, 896, 897*, 915, 916 (Upper), 896, 897* Clam, 423, 424 Claosaurus, 847, 856; annectens, 844* 845*, 847 Clarion coal, 652 ; sandstone, 652 Clastic rocks, 75 Clathropora flabellata, 514 Clathropteris, 740, 750 ; rectiuscula, 749* Clava Chipolana, 917 Clavilithes h'umerosus, 916 ; Missis- sippiensis, 916 ; pachyleurus, 916; Penrosei, 916 Clay, 76, 80, 81 (kinds), 134 Clay-ironstone, 70, 82 Clay marls, 815, 821, 854 Clay shale, 638, 748, 892 ; slate, 80, 84 Clayey layers, plication of, 208, 209* rocks, 12, 313 Clayton beds, 888 Clayton Peak, 360*, 361 Clear Creek limestone, 543, 559 Clear-Fork beds, 660 Clear Lake. See Borax Lake Cleavage in rocks, 92, 112*, 113* 370 Cleodora, 425* Clepsydrops, 687 Clepsysaurus Pennsylvanicus, 753, 754* Cleveland shale, 606, 619, 620 Clidastes, 826 ; iguanavus, 848 ; pro- python, 848 ; velox, 848* CMophorus Pallasi, 707 Cliffs, wearing of, 220, 221* Climacograptus, 514, 520 ; bicornis, 510*; Emmonsi, 470*; typicalis, 516 Climactichnites Fosteri, 479* ; Wil- soni, 479* ; Youngi, 479* Climatal changes, causes of, 253-257 Climatal development, 1026 Climate, effects on the work of rivers, 189 , Cambrian, 484; Carbonic, 711- 712 ; Champlain, 940 ; Cretaceous, 872-873, 877 ; Eocene, 929 ; Gla- cial, 940, 943, 944 ; Lower Silurian, 524; post-Mesozoic, 875, 877; Paleozoic, 727 ; post- Paleozoic, 736 ; Permian, 737 ; Quaternary, 940 ; Tertiary, 921, 939 ; Triassie and Jurassic, 791, 792-793 ; Upper Silurian, 574 Clinch Mountain sandstone, 538 Clinkstone, 85 Clinometer, 100*f ; use of, for meas- uring distant slopes, 28 Clinton beds or epoch, 356, 410, 535 r 540, 544, 549-550, 552 T 563, 570, 572, 577 and Medina, British equiva- lent of, 563 Cliona sulphurea, 158 Clitambonites, 500 ; Americanus T 515 Clupea, 862 Clymenia, 614 (first American), 620 r 626; laevigata, 627; Neapolitana t 614* ; Sedgwicki, 626* ; undulata, 627 Clymenia limestone, 627 Clypeus Hugi, 428* Coahuila Valley, 200 Coal, 62, 124, 136, 143, 154, 485, 727, 775 (jet) ; analyses, 661, 662, 663, 713 ; formation of, from vege* table debris, 712-714 ; impurities, 663, 664 ; kinds, 661 ; origin, 71, 155, 653, 654, 655; plant-remains in, 653-655, 658, 663, 664; struc- ture, 709, 710 ; vegetable material of: kinds and composition, 712, 713 in Calciferous, 493; Carbonifer- ous and Subcarboniferous, 634, 636, 639, 648, 661-664, 674, 693, 694*, 695, 696 ; Permian, 660, 684, 685, 698; Triassie, 742, 744, 745, 748, 755, 769 ; Jurassic, 775, 776 ; Cretaceous, 818, 820, 822, 825, 826, 827, 828, 829, 831, 857, 865, 872 ; Tertiary, 887, 892, 920, 922, 927 areas of N. America, 635, 825 fields of Europe, 693, 694, 696 Coal-beds, bowlders in, 664, 709; burning of, 84, 266, 313 (changed to coke) ; inetamorphic changes in, 315, 453; thickness of, 651, 652, 653, 656, 657, 658 Coal-measures, dirt-beds of, 653, 658 ; false, 639 section of, near Nesquehoning, Pa., 649* ; at Trevorton Gap, Pa., 650* INDEX. 1049 Coal period, 631, 647 Coalville (Utah) coal-bed, 825, 829 group, 825, 829 Coast barriers, 224*, 225* belt. See Coast Chain cordillera, 25 Chain, 390, 739, 818, 937 Range, Cal. and Oregon, 30, 659, 739, 809, 810, 811, 830, 885, 892 of British Columbia, 389, 739, 812 Coastal plains, 24 Coasts, water-line of, 346 Cobalt, 70, 342, 344 ; oxide, 844 Coblenzian beds, 626 ; fauna, 570 Cobscook Bay, 552 Coccolepis, 699 Coccoliths, 72, 140, 437, S38, 859 Cocconeis atmospherica, 163, 164* ; lineata, 163, 164* Cocconema cymbiforme, 163, 164* Coccospheres, 72 Coccosteid, 616* -Coccosteus, 566, 619, 625, 626, 627 ; decipiens, 624* ; macromus, 621 ; occidentals, 588* Coccosteus family, 618 Cochliodonts, 643, 647, 705 -Cochliodus contortus, 644*, 702*; nobilis, 644*, 647 ochlocents, 771 Cockroaches, 156, 419, 574, 677, 721, 723; Carboniferous, 677, 679, 691, 701, 722 ; Paleozoic, 721, 722 ; Per- mian, 686 ; Triassic, 757, 771 Codaster, 516, 601 Ccelacanthus, 679, 680, 692, 705 ; ele- gans, 680*, 692 ; granulatus, 707 Coelenterates, 41 8, 419, 430 Coelodus, 836 Coelospira, 579 ; hemisphaerica, 550 ; Scotica, 567, 569 Coelurus gracilis, 836 Ccenenchyma, 431 Coenograptus graeilis, 510*, 515, 516 Ccenograptus zone of Lapworth, 515 Coffee sands, 824 Coke, 313, 661, 663, 713 'Coleolus, 599 ; acicula, 612, 620 Coleopters, 54, 419, 794, 900 (num- ber at Florissant) ; Coal-measure, 679, 691, 702; Triassie, 771; Gla- cial, 946 Colodon, 918 Colombia, Cretaceous in, 867 Colonoceras, 918 Color of rocks, 400 Colorado, 23 (height), 26, 85, 87, 109, 160, 188, 189, 203, 207, 250, 265, 266, 296, 313, 338, 340, 343, 363, 364, 447 ; silver mines, 340 ; ter- races, 363* ; trachyte, 275* ; see also Front Range of Colorado , Archaean in, 444, 449 ; Cambrian, 464, 476; Trenton, 495, 509, 515; Devonian, 580 ; Subcarboniferous, 469, 639 ; Carboniferous, 469, 475, 658 ; Permian, 693 ; Triassic, 187, 203, 363, 721, 746, 747, 756 ; Juras- sic, 187, 363, 747, 748, 758, 760, 761, 762, 763-; Cretaceous, 187, 574, 363, 82C ,(coal), 828, 880, 847, 848 ; Tertiary, 185, 882, 886, 893, 901, 909, 935 (elevation) ; post-Mesozoic, 876 Canon (Grand Caflon), 107, 186, 187*, 188*, 189, 362, 381, 447, 464, 469, 484, 541, 658, 660, 747 Chain, 389 desert, 160 epoch, 815, 821, 823, 824, 825, 826, 829, 830, 831, 855, 873 plateaus, 109, 110*, 362, 363* Range. See Front Range River, 25, 26, 30, 200, 362 Coloreodon, 918 Colossochelys Atlas, 923, 927 Colubridse, 923 Columbia River, 25, 30, 226, 831, 885, 895 Columbian formation, 974 Columbus limestone, 581 Columnar structure, 261*, 262* Columnaria, 501, 515; alveolata, 504, 505*, 513, 517 ; calicina, 513 ; Halli, 513; incerta, 503; parva, 503 Comanche group (beds), 815, 817, 834, 874* Peak chalk, 817, 819, 836 Comarocystites punctatus, 514 ; Shumardi, 514 Comatulae, 402, 429 Comatulids, 429, 779 Comb (mining term), 333, 722 Comoro Islands, 296 (volcanoes) Compact rocks, 80 Compass, clinometer, 100* Cotnpsacanthus, 692 ; laevis, 692 Compsaster formosus, 646 Compsemys, 850, 856; plicatulus, 767 Compsognathus longipes, 786 Comptonia, 921 Com stock lode, 339 Concentric discoloration, 139, 140* structure, 96*, 97*, 98, 127, 140*, 289, 327 Concepcion, earthquake at, 213, 349 Conchifers. See Lamellibranchs Concretionary consolidation, 139- 140* ; rocks, 79, 80, 82, 96, 139, 344, 690 ; structure, 132, 289, 327 Concretions, 87, 96*, 97*, 139, 152, 195, 230, 274, 307, 327, 493, 603, 605, 606, 657, 665, 677, 688, 775, 822, 825, 847, 888 Condros, sandstones of, 626 Conduit of a volcano. See Vol- cano Conewango basin, 945 Coney Island, 224 Conferva?, 60, 72, 133, 140, 157, 437, 582, 583* Conformability, 114, 115*, 391, 400, 404, 406, 807, 809 Conglomerate, 80, 292 (volcanic), 400 (coral) , limestone, 78 Congo River, 30 Congress Springs, analysis of waters, 121 Conifers, 53 ; ash of, 75 ; time range, 409* Coniophis precedens, 848 Coniston grits, 563 ; limestone, 518, 519, 520 Connecticut, mean height, 23 ; Branchville Mine, 321 ; Thimble Islands, 949 ; copper ores, 745 ; iron ore beds, 127 ; marble, 524, 530, 531 ; Triassic, 111, 740, 741, 742, 751, 753, 754, 755, 799, 800, 801* (map), 808 River, 87, 172, 212 (tide) ; sound- ings at mouth of, 226* Range, 358 Connecticut River valley drift, 956 valley, 194* (terraces), 195, 443 ; Devonian, 310, 531 ; Lower Hel- derberg, 558 ; Niagara, 541 ; Tri- assic, 264, 316, 740 trough, 461, 536, 537, 541, 633, 715, 743 Connellsville sandstone, 651 Connoquenessing sandstones, 656 Conocardium, 520, 562, 621 ; aequi- costatum, 567 ; cuneus, 585*, 590 ; dipterum, 519* ; immaturum, 514 ; Meekanum, 647 Conocephalites, 482, 483 Conocoryphe, 481, 482 ; minuta, 479* Conodonts, 621 Conomitra Hammakeri, 916 Conophyllum magnificum, 590 Conorbis alatoideus, 916 Consolidation (see also Solidifica- tion), 289; by calcareous waters, 133, 139 ; by ferruginous waters, 134, 139 ; by iron oxide, 128 ; by metamorphism, 316, 322; by sili- ceous solutions, 135, 139, 313, 823, 800 , concretionary, 139-140* of coral reefs, 151 Constance, Lake, 921 Contact-minerals and contact-phe- nomena, 312, 313, 314, 333, 810 ; veins, 334 Continent, definition of, 34, 35 making, 376 Continental border, 743, 744 Interior. See Interior Continen- tal plateaus, 379 Continents, 383 ; arrangement of, 17, 21 ; as individuals, 22 ; heights of, 23, 380 ; mostly in the northern hemisphere, 394 , mountain chains and volcanoes mostly on the borders of, 392 , northern and southern, in a zigzag arrangement, 394 , origin of, 383 ; submerged bor- ders, 17 ; system in reliefs, 30-35 Continguiban group, 867 Contraction, effects of, 260, 327, 381 ; in glass and rock, 264, 265 ; in volcanic work, 283 ; on drying and on cooling makes fissures, 32T theory of mountain-making, 883- 386 and expansion, 259-265, 261*, 1050 INDEX. Conularia, 481, 488, 506, 514, 549, 562, 567, 574, 578, 579, 613, 698, 705, 707, 719 (time range) ; elegantula, 590; formosa, 516; Homfrayi, 520 ; lata, 578 ; longa, 551 ; Niaga- rensis, 551 ; Trentonensis, 507*, 514, 516 Conulites flexuosus, 562 Conulus chersina, 966 Conus, 916, 922; deperditus, 926; Okhotensis, 927 Cook's Inlet, 760 Cooling, contraction from, in case of fusion, 261*, 263, 264, 883 of the globe, 376 ; its conse- quences, 383, 939 Cooper beds, 888 Coosa coal-fields, 657 ; series, 468 Copepods, 421 Copiapo earthquake, 349 Copodus, 643 Copper, 70, 333; chloride, 294; native, in drift, 953 ; oxide, 344 ; pyrites (see Chalcopyrite) ; see also Superior (Lake) region, cop- per Copperas, 123, 125 Coprolites, 73 (analyses); Upper Silurian, 567; Triassic, 754; Ju- rassic, 785, 786* Coral, precious, 72, 431; Coral atolls (see Atolls) bed, Taylorville, Cal., 759 beds of the Siliceous group of Tennessee, 688 formations, 144-152 island, water supply of, 206 subsidence, 936-937 islands, 20, 120, 131, 144, 145- 148, 145*, 146*, 161, 221, 225, 295, 350, 392, 937 ; most numerous in the tropical Pacific, 145 ; number in the several groups, 145; sec- tions of, 149*, 284*, 285* oolyte, 147 polyps. See Polyps rag, 411, 775, 790 reef period, in the Devonian, 584 --reefs, 144, 148-152 Corallian group, 760, 775, 777, 780, 790 Coralline limestone of the Niagara, 540, 543, 549 Corallines, 56, 72, 437 Coralliochama Orcutti, 841* Coralliophila magna, 916 Corallium nobile, 72 Corals, 55, 140, 427*, 429*; limits of growth, 144, 145, 146, 149* Corax, 843 ; heterodon, 843* Corbicula, 828, 829 ; annosa, 837 ; cytheriformis, 856; densata, 917; emacerata, 837 ; occidentals, 856 Corbis distans, 916 Corbula, 756, 780, 828, 916, 917; Aldrichi, 915 ; Forbesiana, 791 ; idonea, 917 ; inflexa, 791 ; longi- rostris, 925 ; Neocomiensis, 867 ; oniscus var. fossata, 916; pecti- nata, 791 ; pisum, 926 Cordaianthus, 673* Cordaicarpus Gutbieri. 673*, 689 Cordaites, 435, 611, 612, 639, 667, 672, 673*, 674, 689, 699, 704 ; bo- rassifolius, 646, 689 ; Clarki, 610, 621 ; costatus, 672*, 689 ; diversi- folius, 689; Gutbieri, 673* ; Mans- fieldi, 672 ; Robbii, 595*, 596, 601, 622 Cordaites shales, 693, 594 Cordillera, 25, 3S9, 390 of the Rocky Mts., 390 Cordillera glacial area, 956 Cordylocrinus, 562 Corea, 40 Cork, composition of, 713 Cormorant, 852, 902 Cornbrash, 775, 790 Corneo-siliceous sponges, 431 Corneous sponges, 431 Corniferous limestone, 576, 579 Corniferous period, 579 Corniornis, 852 Cornulites serpularius, 567 Cornus suborbifera, 839 Cornwall, 317, 936 (united with Brittany) veins, 329*, 332*, 333* Cornwallis I si., 495 Coroniceras Bucklandi, 781*, 790 Coronocrinus, 562 Coronura, 591 Corrasion, 168, 941 Correlation of geological records, 398-404 (difficulties, 398 ; means, 399; precautions in the use of fossils, 402) ; difficult in crystal- line terranes, 458 of Archaean subdivisions, 457 Corrosion, 126, 136, 338-342 . Corsica, 87 Corsyte, 87 Cortez Range, 366 Corundum, 64, 79, 320, 455 Corycephalus, 591 Corydalis Brongniarti, 704 Coryphodon, 903, 907, 917, 918, 923, 925, 929 ; hainatus, 903, 904* Coryphodon beds, 886 Coryphodonts, 928 Coscinodiscus, 163, 164* ; apicula- tus, 894* ; atmosphericus, 168, 164* ; gigas, 894* Coseguina volcano, 163 Cosmoceras Jason, 781* ; Parkin- soni, 790 Cosoryx, 911, 919 Costa Rica, 891 (Miocene) Coteau des Prairies, 942 (drift), 945 Cotopaxi (Mt.), 26, 274, 296 Cottonwood Canon, 469, 476, 581 Creek, 895 Country Peak, 783 rock, 331 Coutchiching, 446 Crabs, 146, 420*, 488, 707, 717, 720, 782 Crag, Pliocene of England, 921, 927 Craie glauconieuse, 866 Cranberry mine, 450 Cranes, 923 Crania, 59, 425, 516, 520, 719 ; an- tiqua, 427* ; divaricata, 519*, 520 ; scabiosa, 514, 516 Crassatella, 916; alaeformis, 915; alta, 897*, 916 ; antestriata, 915 ; curta, 854; flexura, 916; lineata, 855; littoralis, 854; melina, 917; Marylandica, 917 ; Mississippien- sis, 916; sulcata, 926; texalta, 916; Texana, 916; Trapaquara. 916; tumidula, 915; undulata, 917 ; vadosa, 854 Craters, 267, 269*, 270*, 284*, 28G* ;. see also Volcanoes Craw-fish, 158, 771 Crazy Mts., 876 Crenitic hypothesis of Hunt, 321 Creodonts, 903, 906, 907, 917, 918, 923, 924, 925 Crepicephalus, 503 Crepidula, 642 ; costata, 900* ; forni- cata, 994 Cretaceous period, 812; N. Ameri- can, 812 ; foreign, 856 in N. America, map of, 812, 813* v 814 , Lower, 816 , Upper, 837 Cretacic period. See Cretaceous Cricoceras Dtivalii, 862* Cricodus, 417* Cricotus Gibsoni, 687 ; heteroclitus, 687* Crillon (Mt.), 238 Crinidea (Crinideans), 429 Crinoidal limestones, 404, 594, 636,. 652 Crinoids, 60, 72, 138, 140, 142, 310, 314, 402, 428*, 429*, 430, 486, 532*, 541 Criocardium dumosum, 854 Cristellaria cultrata, 791 Crocodiles, 54, 415; Jurassic, 768; Tertiary, 901, 902, 923, 927 Crocodilians, Cretaceous, 848, 863, 870, 871 ; Jurassic, 760, 787 ; Tri- assic, 751, 754*, 758, 772, 773 Crocodilus Elliotti, 901 ; Hastings!*,. 926; Squankensis, 901 Cromer forest bed, 927 Crooked River, 749 Cross-bedded structure, 92, 93*, 194, 603, 658, 742, 825, 827, 888 Cross Sound, 288 Cross-Timber (Lower) sands, 815, 824, 854 Crossopterygians, 417, 619, 725 Crotalocrinus rugosus, 564*, 565 r 567 Croton River water analyzed, 121 Crushing, 259, 322, 326, 338, 452 Crustaceans, 420*, 421, 422, 423, 437, 438; derivation, 720-721; tracks, 95, 742 Crustal movements, 345, 800 Cruziana, 474 ; bilobata, 545*, 546 ; similis, 477*, 478 Cryoconite, 241 Cryolite, 449 Cryphseus, 591 ; Boothi, 614 Cryptacanthia compacta, 690 Cryptoceras capax, 691 INDEX. 1051 Cryptodon angulatus, 925 Cryptogams, 53} 136, 140, 434, 435- 437, 519, 595, 668 (vascular), 672, 718; Corniferous, 583*; Carbo- niferous, 666, 727 (culmination) ; Neopaleozoic, 460 (culmination) Cryptonella, 579 ; eudora, 620 ; lens, 585* Cryptozoon proliferum, 500 Crystal kingdom, 9 Crystallization, 76, 408 ; alongside of dikes, 312, 313; see also Meta- morphism Crystallophyllian, 440 (Archaean synonymy) Crystals, figures of, explained, 63 Ctenacanthus, 644 ; Bohemicus, 567 ; latispinosus, 591 ; major, 702, 703* ; Wrighti, 601 Ctenacodon, 768 ; potens, 767* ; serratus, 767* Ctenodonta, 481, 520, 521 Ctenodus, 687, 702 ; Nelsoni, 617* Ctenoids, 417*, 836 Ctenoptychius, 692, 702 Cuba, 19, 347, 872, 936 Cubical coal, 661 Cuboides shale, 627 ; zone, 593, 594 Cuchara basin, 893 Cucullaea capax, 854 ; gigantea, 915 ; Haguei, 760; macrodonta, 915; oblonga, 791 Cumberland Measures, 648 Table-land, 25, 356*, 357, 362, 38C, 648 (Va.) Triassic area, 741 valley, 357 Cumbrian Mts., 463 Cuneolina pavonia, 432*, 860* Cup-corals. See Cyathophylloids Cupressinoxylon, 921 Cupressites, 777 Cuprite, 385 Curagoa, 891 (Miocene) Curculio family, 771 Curculionites prodromus, 771 Current-bedding, 93 Cutch, 299, 791 Cuttle-fishes, 424, 525, 869 (time range) ; bone, 424 Cuyahoga River, 942 Cyanite, 65, 66, 83, 318, 319, 449 Cyanitic rocks, 83 Cyathaspis, 625 Cyathaxonia, 718 / ! Cyathea compta, 669*, 689 Cyathocrinus, 597, 646, 690, 707 Cyathophycus reticulatus, 515 ; subsphaericus, 515 Cyathophylloids, 431, 718 (living) Cyathophyllum limestone, 704 Cybele, 521 Cycadeoidea Abequidensis, 755 ; Jenneyana, 832 ; Marylandica, 831 ; munita, 832 Cycads, 53, 409*, 434*, 435, 718, 831, 868; Devonian, 409; Ham- ilton, 596 ; Carboniferous, 666, 667, 672*, 682 ; Permian, 685, 698, 704 ; Triassic, 749*, 750, 756*, 770*, 868 ; Jurassic, 776, 777, 819, 868; Mesozoic, 738, 879; Creta- ceous, 794, 815, 818, 868, 869, 873, 877 Cycas circinalis, 434*, 750 Cyclocardia borealis, 984 Cycloceras, 675 ; anellum, 514 Cycloids, 417* Cyclonema, 520, 521, 613 ; bilix, 514, 516 ; cancellatum, 546*, 550 ; Cincinnatiense, 516 ; corallii, 567 ; quadristriatum, 567 Cyclophthalmus senior, 701*, 703 Cyclopidius beds, 886 Cyclops, 421, 423 Cyclopteris, 698 ; Acadica, 645 ; Browni, 622 ; Hibernica, 626 Cyclora parvula, 516 Cyclospira bisulcata, 507*, 514 Cyclostigma, 699 ; aftine, 610 ; minu- tum, 626 ; Kiltorkense, 626, 704 Cyclostomes, 418 Cyclothone, 60 Cyclus, 720 ; Americanus, 676, 691 Cymatolite, 321 Cymbella maculata, 163, 164*; Scotica, 699 Cymoglossa, 685 Cynodesmus, 918 Cynodictis, 926 Cynodon, 911, 918 ; Parisiensis, 924, 926 Cynodontomys, 918 Cyphaspis, 513, 516, 521, 562, 568, 579, 586, 591, 599; laevis, 614; megalops, 565*, 567 Cypraea, 916, 922 ; Carolinensis, 900* Cypress, 770*, 939 Cypricardella bellistriata, 598* Cypricar,dia, 525, 621 Cypricardinia, 562 Cypricardites Montrealensis, 503; Niota, 514 ; rectirostris, 514 ; Sterlingensis, 516 Cypridina serrato-striata, 627* Cypridina shale, 627* Cyprimeria depressa, 854 Cyprina Brongniarti, 791 ; Morrisii, 925 Cypris, 420*, 421 Cyrena, 855 ; arenarea, 855 ; con- vexa, 926; cuneiformis, 925; pulchra, 926 ; semistriata, 926 ; tellinella, 925 Cyrtia exporrecta, 567 Cyrtina, 562, 579, 591; rostrata, 579, 591 ; triquetra, 602 ; umbo- nata, 602 Cyrtoceras, 482, 488, 520, 521, 551, 561, 562, 568, 586, 591, 599, 625, 627 ; dorsatum, 685 ; ornatum, 516; subannulatum, 506, 508*, 514; subrectum, 558; Vassari- num, 499, 500* Cyrtolites, 506, 516 ; carinatus, 516 ; compressus, 507*, 514; imbrica- tus, 516; ornatus, 516; Trento- nensis, 507*, 514 Cystideans. See Cystoids Cystiphyllum, 552, 597, 640 ; Ameri- canum, 590, 601 ; conifollis, 601 ; Siluriense, 564*, 567 ; varians, 601 Cystoids, 140, 429*, 430, 570 ; Cam- brian, 470, 474, 477, 482, 486, 719 (first) ; Calciferous, 499 ; Chazy, 501, 503; Trenton, 505*, 514; Utica and Hudson, 511, 516; Lower Helderberg, 559*, 560, 561 ; Devonian, 577, 719; Paleozoic, 719 Cythara terminula, 917 Cythere Americana, 420*, 691 Cytherea aequorea, 916; imitabilis, 916; Marylandica, 917; Mortoni, 916 ; ovata, 915 ; sobrina, 916 ; staminea, 917 Cytheropsis, 516 Dachstein beds, 769, 774 Dactyloporus archaeus, 688 Dacyte, 86, 272, 273, 296, 304, 937 Dadoxylon, 596, 612, 704; antiquum, 646 ; Clarki, 610, 621 ; Edwardi- anum, 755 ; Ouangondianum, 622 Dadoxylon sandstone, 594 Daemonelix, 914, 915* Dakota, Archaean in, 444 ; Cam- brian, 466 ; Cretaceous, 818, 826, 827, 837, 838, 846, 848, 852 ; Ju- rassic, 760 ; Niagara, 543 ; Ter- tiary, 886, 902, 919 ; Triassic, 746. See also North D. ; South D. Dakota epoch or group, 758, 818, 821, 823, 824, 825, 829, 830, 833, 887, 839, 840, 855, 872 Dalmanites, 310, 422, 503, 513, 521, 546, 551, 561, 570, 578, 579, 586, 591, 599, 627 ; aspectans, 587*, 591 ; Boothi, 587*, 591, 599, 614 ; breviceps, 516 ; callicephalus, 515 ; calliteles, 599* ; dentatus, 578 ; Hausmanni, 421*, 422, 568, 570; limulucus, 549*, 551 ; nasutus, 561 ; phacoptyx, 579 ; pleuro- pteryx, 561, 562, 591; regalis, 587*, 591 ; selenurus, 587*, 591 ; tridens, 561 Dalradian group, 456 Damourite, 65, 84 ; slate, 84 Damuda series, 698, 699 Dan River Triassic, 741, 743 Dana Bay, 606 Dana Mt., glaciers on, 240, 945 Danaeopsis, 774 Danburite, 63, 449 Danian epoch, 815, 858, 859, 866 Danube, 176; loess of, 195; sedi- ment in, 190 ; denudation, 191 Daonella, 756; Lommeli, 757, 758, 774 ; tenuistriata, 757 Dapedius, 784* Daphaenus, 918 Daphnia, 421 Daptinus, 863 Darien, Isttimus of, 22, 41, 256 Darlington ca^nel coal, 676 Dasyceps Bucklandi, 706 Datolite, 63 Dauphine, 176, 927 Davallia tenuifolia, 840 Davidson Glacier, 240 Davis Strait. 40 Dawsonella Meeki, 676*, 690 Dayia navicula, 568 Dead Sea, 23, 49, 199, 256 1052 INDEX. Death Gulch, 128 Death Valley, 23, 128, 200 Debris-cones, 269*, 271, 285 Decapods, 420, 423, 424, 438, 439, 525, 615, 676, 691, 707, 720 Deccan, igneous outflows of, 299, 876, 938 Deception Island, 296 Decomposition, 258, 497, 522, 655, 665, 710, 822 Deep River, or Deep Creek, Mon- tana, 895 beds, 886, 894, 911, 919 Deep River (N. C.) Triassic area, 741, 743, 799 Deer, 54, 910, 911, 924, 927, 930 Deflation, 159 Deformation of fossils. See Fossils Degeneration, 717 ; in Insects, 721 ; in Reptiles, 797, 870; in Am- phibians, 869 ; in Birds, 871 ; in Mammals, 931, 1017 Deistersandstein, 865 Delaware, 23 (height), 87, 856; Cretaceous in, 816, 823 Bay, 230, 378, 744, 819 flags, 606 ; limestone, 581 River, 594, 744, 816, 945 Water Gap, 232, 578 Delocrinus, 690 Delphinapterus catodon, 983 ; leucas, 983, 1001* Delphinus, 144, 927 Delta formations, 98, 191, 195, 196- 198, 197*, 892 Delta Survey, 190 Deltatherium, 917 Delthyris. See Spirifer Delthyris shaly limestone, 559 Deltodus, 692 Demavend (Mt), 296 (height) Denbighshire grits, 563, 564 Dendrerpeton, 682 Dendrocrinus Cambrensis, 481 ; Cincinnatiensis, 516 ; retractilis, 514 Dendrodus, 625, 647 Dendrograptus, 520 ; gracillimus, 516 ; Hallianus, 477* ; tenuira- mosus, 516 Dendrophis, 704 Dendrophylla, 429* Denison beds, 817, 837 Denmark, Cretaceous in, 856, 857, 858 Density of the earth, 15, 376; of the moon, Mercury, Yenus, Mars, Jupiter, 16 ; of mountains, 379 Dent de Morcles, profile of, 367* Dent du Midi, 920 Dentalina priscilla, 690 Dentalium, 424, 707 ; attenuatum, 917 ; Meekianum, 690 ; Missis- sippiense, 898*, 916 ; sublaeve, 675*, 690 ; venustum, 647 Denudation by the atmosphere, 159, 160*, 161*; by glaciers, 247- 251 ; by water, 167-169, 177-189, 186*, 451, 934 ; by waves, 217, 218, 219, 221, 882 Denudation, relations of mountain ranges to, 387-388 Denver, 364 group, 815, 825, 827, 828, 829, 830, 839, 847, 856, 875 Deoxidation, 124, 127, 128; de- structive effects of, 125, 126*, 127* ; through the growth of plants, 136 Deposition, by glaciers, 247, 250; by water, 169-170, 189-202, 216, 628 ; by waves, 222 ; by winds, 161 Deposits, ore. See Ore. See also Sediment Derbya crassa, 690 Derivation of Arachnids, 722-723 ; Limuloids and Crustaceans, 720- 721 ; Myriapods and Insects, 723- 724 Desatoya Mts., 757 Des Chutes River, 894 Deserts, distribution of, 50, 51 ; sands of, 160, 161 Desmatippus, 911, 912, 919 Desmatochelys Lowii, 849 Desmids, 437, 859; in hornstone or flint, 582, 583*, 859 Desmoceras Breweri, 837 Destruction of life. See Life Detritus, 75, 81, 167 Devil-fishes, 424 Devonian (or Devonic) era, 575; North American, 575 ; Oriskany, 577; Corniferous, 579 ; Hamilton, 592 ; Chemung (with Catskill), 602; foreign, 622; geological and geographical progress, 628 ; bio- logical, 630 ; upturning, 630 relations of the Lower Helder- berg fauna, the Hercynian ques- tion, 569-570 Diabase, 87, 273, 319, 325, 339, 453, 457, 468, 469, 518, 748, 802 Diabase-schist, 87 Diablerets, 920 Diablo, Mt., 835, 892 Diaclases, 113 Diacodon, 918 Diadema, 59 Diallage, 88 ; rock, 87 ; structure, 321 Diamond, 62, 64, 319, 455 Diamond Head, Oahu, 271* Diamond Mt., 733 Diaspore, 320 Diatom ooze, 57, 143 Diatoma vulgare, 699 Diatomaceous earth, 889 Diatoms, 56, 57, 60, 64, 72, 81, 121, 135, 136, 140, 142, 143, 152, 153, 163, 164*, 229, 319, 433*, 436, 437*, 699, 817, 859, 887, 895 ; in flint, 582, 583* Diatryma gigantea, 902 Dicellocephalus, 477, 478, 481, 483, 500, 502, 503, 516 ; lowensis, 479* ; Minnesotensis, 478, 479* Diceras, 780, 877 (end) ; arietinum, 780*, 790 ; Lonsdalei, 865 Diceratherium, 911, 918 Diceratian, 790 Dichobune, 926 ; cervinum, 926 Dichocrinus, 646 Dichodon, 926 ; cuspidatus, 926 Diclonius mirabilis, 846 Dicotyles, 54, 1002 ; nasutus, 1000 ; Pennsylvanicus, 1012 Dicranograptus ramosus, 510*, 515, 516 Dicranophyllum, 673 Dictyocaris, 567 Dictyocha, 894* ; crux, 894* Dictyo-cordaites Lacoei, 610* Dictyonema, 481, 550, 590 Dictyonema shales, 482 Dictyoneura anthracophila, 701*, 702, 704; Humboldtiana, 703; Monyi, 702 Dictyophyton, 432 ; tuberosum, 611*, 621 _ Dictyopteris, 699 Dictyorhabdus priscus, 509* Dicynodon, 707, 737, 778 Didelphis, 925 Didelphodus, 918 Didelphops, 853* ; comptus, 853* ; ferox, 853* ; vorax, 853* Didelphys, 55, 910, 918 Didus ineptus, 54, 1014 Didymictis, 917, 918 Didymites globus, 774 ; tectus, 774 Didymograptus, 520 ; extensus, 500 Dieconeura, 691 Dielasma, 642 ; bovidens, 690 ; elongata, 707 ; hastata, 700* Dikes, 90, 262*, 264, 298, 299*, 302, 327 Diloma ruderata, 927 Dimetian period of Hicks, 457 Dimetrodon, 688 Dimorphodon, 788 Dinarites Liccanus, 778 Dindymine, 521 Dinichthys, 603, 618; Hertzeri, 617*, 619 ; Gouldi, 619 Dinictis, 911, 918 Dinoceras, 907 ; size of brain of, 914* ; mirabilis, 907 Dinoceras beds, 886 Dinophis, 901 Dinornis, 54, 1014, 1019 ; giganteus, 54, 1014 Dinosaurs, Triassic, 741, 751 ; Ju- rassic, 760, 768, 785, 796 ; Cre- taceous, 816, 828, 836, 844*, 856, 863*, 867, 870 ; relation to Birds, 796 Dinotherium, 927 ; giganteum, 924, 925* Dinotosaurus, 785 Dionide, 521 Dioonites, 832 ; borealis, 833 ; Buch- ianus, 832*, 834; Columbianus, 834 ; Dunkerianus, 834 Diopside, 318, 328 Dioryte, 86, 97* ; schist, 86 Diospyros, 922 Dip, 99*, 105, 114* Dipeltis diplodiscus, 691 Diphya limestone, 791 Diphyphyllum, 550, 640; arundi- naceum, 591 ; fasciculum, 592 ; stramineum, 591 INDEX. 1053 Diplacodon, 90T, 918 Diplacodon beds, 886 Diplaspis Acadica, 546 Diplocynodon victor, 767* Diplodocus longus, 762* Diplodonta acclinis, 917 Diplodus, 687, 692 ; compressus, 692 ; Gaudryi, 702 ; gracilis, 692 ; latus, 692 Diplograptus, 520 ; amplexicaulis, 505*, 514; inucronatus, 510*; pristis, 510*; spinulosus, 516; Whitfieldi, 516 Diploopoda, 419 Diplopterus, 627 Diplurus longicaudatus, 751 Dipnoans, 417 ; Paleozoic, 587, 588*, 617*, 618, 619, 625*, 725, 727; post-Paleozoic, 736; Per- mian, 687 ; Triassic, 772, 869 Dipnoi, 54, 59, 417 Dipriodon lunatus, 853* Diprionidae, 498*, 499 Diprotodon Australia, 1006* Dipterocaris penna - Daedali, 615* ; Procne, 615* Dipters, 419, 679, 783, 794, 900 (number of Florissant) Dipterus, 625, 627 ; macrolepidotus, 625* ; Sherwoodi, 617* Disappearance of life. See Life Discina, 59, 72, 425, 447, 475, 481, 482^ 487 ; Caerfaiensis, 481 ; lamel- losa, 427* ; Lodensis, 627 ; trun- cata, 612, 620 Discinids, 779, 922 Discinisca lamellosa, 427* Discites, 591, 602, 642, 700 Disco Bay, 244, 350 Disco Island, 272, 376, 819, 831, 921 Discosorus, 546, 549 ; conoideus, 546 Dismal Swamp, 154, 889 Displacements through frost, 230, 231*. See also Faults ; Flexures ; Fractures Dissacus, 917, 918 Distortions of beds and fossils, 107, 369, 370*, 371 Distortrix septemdentata, 916 Disturbances, 351 , 363, 406 ; of clos- ing Archaean, 466 Dithyrocaris Belli, 602 ; carbonaria, 691 Ditroyte, 85 Dockum beds, 660 Docodon striatus, 767* Dodo, 54, 1014* Dosdicurus, 1017 ; clavicaudatus, 1003 Dog, 924 Doggers of the Oolyte, 775, 776 Dolatocrinus, 590 Doleryte, 78, 85, 87 Dolichopterus, 557 Dolichosaurs, 870 Dolichosoma, 692 ; longissimum, 704 Dolomite, 68* Dolomization. See Dolomyte, mak- ing of Dolomyte, 78, 79 ; making of, 133, 134, 343, 524 Dolphin shoal, 19, 20, 217 Dolphins, 912 Domatoceras umbilicatum, 691 Dombeyopsis obtusa, 839 ; squar- rosa, 839 Domnina, 918 Donax, 916 Dordonian, 859, 866 Doropyge, 482 Dorycrinus unicornis, 640*, 646 Dosinia, 916 ; acetabula, 917 Dosiniopsis lenticularis, 915 ; lenti- cularis var. Meekii, 897* Double Mountain beds, 660 Drainage, antecedent, consequent, superimposed, 203 ; reversed. 947 courses, direction of, 177, 888 Drepanacanthus, 692 ; anceps, 692 Drepanis Pacifica, 1014 Drepanocheilus Americanus, 841* Drepanophycus, 590 Drift, 184, 916, 942 Drift-sand hills, 94, 161, 162, 213 Dripstone, 79, 131 Dromaeus, 54 Dromatherium, 754, 768, 773; syl- vestre, 754* Dromopus, 682 ; agilis, 684* Dromornis, 1019 Drumlins, 942 Drummond Island, 542 Dry Creek, Wyoming, 907 Dryolestes priscus, 767*; vorax, 767* Dryopithecus, 927 Dryptodon, 917 Duckbill, 53, 415 Dudley limestone, 563 Dugong, 925 Dundas gorge, 946 Dunes, 162, 265 Dunvegan beds (group), 830, 840 Dunyte, 89 Dust, transportation of, 159, 195; showers of, 163, 164* ; on gla- ciers, 235, 241 Dwyka bowlder bed, 699 Dyas. See Permian period Dyke. See Dike Dysaster ovulum, 865 Dysintrybyte, 84 Dystrophseus Viaemalae, 758 Eager, 212, 215 Eagle, 902 Ford shales, 815, 824, 854 Pass beds, 824, 855 ray, 643 Earth, 15 (density), 376 (specific gravity) ; general contour and surface subdivisions, 15-30 Earth as an individual, 9, 10, 393; relation of to the universe, 10 ; proportion of land and water, 16 ; system in the courses of feature lines, 35-42, 393 , changes in the ellipticity of its orbit, 254, 255 ; in the position of its axis of rotation, 255, 346 ; its circumference shortened in moun- tain-making, 391 ; heat reached the surface in three ways, 258 Earth, polar diameter maximum and minimum, 1027 , development of, 391, 1027^ thickness of the supercrust, 209, 377 Earth-shaping, mountain-making,, and attendant phenomena, 345- 396 (changes of level, 345; dis- turbed regions, 351 ; typical mountain ^ranges, 353 ; subordi- nate effects of orographic move- ments, 369 ; origin of the earth's form and features, 376) Earth (soil), 75, 76, 137 (nitrifica- tion) Earth-worm, 156, 423 Earthquake waves (oceanic), 218,. 221, 875 Earthquakes, 222, 229, 265, 286, 287, 344, 349, 372-375, 386, 875 ; cause of exterminations, 877 ; geolo- gical effects, 375 ; not essential in volcanic eruptions, 286 East Indies, 17, 19, 21, 44, 145> (coral reefs) ; trends of the islands, 38, 39, 40; volcanoes, 295, 296, 297 East River, Pictou, 533, 543 East Rock dike, 299*, 302*, 303, 312, 804, 806 Eastern-border life of N. America related to European, 572-573 Interior region of N. America, 576, 578, 633, 636 Sea of N. America, 537, 539, 541, 558, 571, 575, 579, 580, 628, 629, 633, 734 Eatonia, 562, 579; medians, 579; peculiaris, 579; singularis, 560*, 562 Ebb-and-flow structure, 93* Ecca beds, 698, 699, 770 Eccentricity cycle, influence of, on climate, 254, 978, 1027 Eccyliomphalus priscus, 500 Echidna, 53, 415, 795, 798 Echinids, 59 Echinocaris, 599, 615; Beecheri,. 621 ; punctata, 600* ; socialis, 621 ; Whitfieldi, 621 Echinoderms, 59, 130, 140, 144, 158, 418, 419, 427, 428*, 429*, 430;. Cambrian, 469, 480; Calciferous, 499,500 Echinognathus Cleveland!, 513* Echinoids, 428*, 429*, 430, 525, 641* Echinosphaerites, 520, 521 Echinus, 157, 427, 428*, 429*, 879 Echo, 360*, 362 Echo Cliffs, 363* Eclogyte, 88 Ecphora quadricostata, 899*, 917 Ectacodon, 918 Ecuador, 935 (heights) Eddies, 184 Edentates, 54, 919, 924 (first), 927 Edestosaurus, 826 ; dispar, 849* ; velox, 848* Edestus, 680 ; giganteus, 680, 681*;. minor, 680, 681* 1054 INDEX. Edmondia, 621, 622 Edriocrinus, 562, 577 ; sacculus, 579 Egan Kange, 365 Eggs, fossil, 787 Egypt, 160, 162 ; Cretaceous of, 857 ; Tertiary of, 920 Eifel, 289, 297, 568, 602, 627, 938 Eifelian beds, 626, 627 Eiger, 236 Eileticus anthracinus, 691 Eteolite, 65, 85, 449 ; syenyte, 532, 876 Elasmobranchs, 587 Elasmosaurus, 845 ; platyurus, 845 Electric Peak, 987 Elephant, 54, 402, 903, 924, 925, 927, 931 Elephas, 927 ; Africanus, 1016 ; Americanus, 998 ; antiquus, 927, 1006; Columbi, 1001 ; Melitensis, 1006 ; meridionalis, 927 ; primi- genius, 966*, 997, 1000, 1004, 1005, 1006, 1009', 1015 Elgin sandstones, 773 Elginia mirabilis, 773 Elizabeth Island, elevation, 350 Elk, 950 (migration) Elk Mountain sandstone and shale, 606 Elk Mts., 106*, 363, 364*, 689 Ellipsocephalus, 482 Elm, 435, 837 Elotherium, 909, 911, 918 ; crassum, 909* Embryonoid, 423 Emerald Island, 39 Emery, 64, 455 Emeu, 54 Emigrant Peak, 937 Empo, 843 Emys, 901, 926 Enaliornis, 864 Enaliosaurs, 682, 760 Enallaster, 834 ; Texanus, 834*, 836 Encephalartos denticulatus, 756* Encephalaspis, 588 Enclimatoceras Ulrichi, 896*, 915 Encrinal limestone, 543, 559, 593, 638, 728 Encrinites, 429, 430, 559 Encrinurus, 515, 521, 551, 552 ; Isevis, 569 ; punctatus, 565*, 567, 568 ; variolaris, 565*, 567 Encrinus, 719 ; liliiformis, 429*, 770, 771*, 774 Endoceras, 501, 506, 508, 511, 514, 516, 520, 591 ; proteiforme, 514, 516 Endogenous work, 867 Endogens, 434, 435 Endolobus gibbosus, 691 ; spec- tabilis, 642 Endothyra Baileyi, 646 England, 19, 32, 48, 162, 219, 234, 256, 297 (volcanoes), 874 (earth- quakes), 431, 464, 760; disturb- ances and upturnings in, 534, 630, 733 ; geological map of, 693, 694* , Archaean in, 456 ; Cambrian, 480,484 Engonoceras Gervillianum, 865 Enhydriodon, 927 Enhydrocycn, 918 Enneodon crassus, 767* Enniskillen oil wells, 581 Enstatite, 67, 88 Entolium, 760; avicula, 690; gib- bosum, 759* Entomis, 567, 621 Entomostracans, 420, 421, 423, 439, 525, 574 Eocarboniferous period, 632 Eocene lakes of N. America, 882, 893, 894, 929, 933 Eocene period. See Tertiary Eocystites, 474 ; longidactylus, 474* Eodevonian, 576 Eogene, 880 Eohippus, 905, 918 ; pernix, 905* Eohyus, 918 ; distans, 907 Eolian, 159 Eolian formations, characteristics of, 162 Eolian limestone, 491, 517, 528 Eolignitic, 885, 888 Eolus, Mt., 530* Eopaleozoic time, 407, 460, 462- 535, 716 Eophrynus Prestwichii, 703 Eophyton, 482 Eophyton sandstone, 4*82 Eosaurus Acadianus, 682, 683* Eoscorpius carbonarius, 678* ; "Woodianus, 691 Eospongia Rcemeri, 503 ; varians, 503 Eozoic, 442 Eozoon, 319, 454, 455; Bavaricum, 455 ; Canadense, 454* Eparchaean, 446 Epeirogenic movements, 376, 388, 392 ; of the Tertiary, 933-937 ; of the Quaternary, 1020 Ephedra, 435 Ephemera, 600 Ephemerids, 600 Ephippioceras divisum, 691 Epiaster elegans, 837 ; polygonus, 865 Epicentrum of an earthquake, 374, 375 Epidosyte, 88 Epidote, 66, 82, 85, 88, 312, 315, 318, 331 ; gneiss, 88 ; rocks, 88, 89 Epihippus, 912, 918 ; gracilis, 907 Epipodite, 422 Epithemia Argus, 163, 164* ; gibba, 163, 164*, 699; gibberula, 163, 164* ; longicornis, 163, 164* Epoch, 406 Eporeodon, 911, 918 Epsom salts, 555 Epsomites, 555 Equiseta, 434, 436, 560, 663, 667, 672, 711 Equisetites, 685 ; rugosus, 704 Equisetum, 74 (ash), 519; arena- ceum, 773 ; arvense, 74 ; hyemale, 75 ; telmateia, 74, 75 Equivalence of strata, 398, 401, 815 Equus, 913*, 919, 927, 1002 ; cabal- lus, 1004, 1005; excelsus, 999; fraternus, 1001 ; major, 1001, 1002 ; simplicidens, 912 ; Stenonis, 927 Equus beds, 892, 1000 Eras, 406; reality and character- istics of geological, 397 Erebus, Mt., 296 (height) Eremopteris, 689, 699 Erian, 576, 590 Erie clays, 972 Erie, Lake, 200, 947, 986 Erie shale, 606 Erinaceus, 927 Eriptychius Americanus, 509* Erosion, 258, 300, 388, 390, 533, 647, 709, 827, 828, 868, 875, 894, 934; by carbonated water with humus acids, 129; by drift sands, 160; by rivers, 167, 178, 181*, 183*, 195, 196*, 943; by water containing carbonic acid, 130, 131 ; in the Carboniferous, 709 ; causing un- conformability, 115, 116. See also Denudation , Monument Park, 186* Eruptions. See Igneous ; Volcanic Eruptive rocks, 76, 265 Eryon arctiformis, 783* Eryops megacephalus, 686*, 687 Eschara, 425*, 427 Eskers, 942, 970 Esopus millstones, 542 Estheria, 600 (oldest known), 623, 774; minuta, 771*, 773, 774; ovata, 750* ; pulex, 600 Estheria shales, 771 Esthonia, Cambrian in, 482, 484 Esthonyx, 917, 918 Estuary deposits, 191 Ethmophyllum, 483 Ethmosphsera, 319 Ethylene oils, 124 Etna (Mt.), 26, 279 Etoblattina, 691, 701 ; primseva, 701*, 704 ; venusta, 679* Eua Island, elevation, 350 Eucalyptocrinus decorus, 550, 551, 567, 568 Eucalyptus, 838* ; Geinitzi, 838* Euchasma Blumenbachii, 500 Eucryptite, 321 Eucryte, 87 Eucyrtidium Mongolfleri, 433* Eudialyte, 85 Eugereon Bockingi, 722 Eulima Texana, 855 Eumetria Verneuiliana, 642*, 646 Eumicrotis curta, 757, 760 Eumys, 918 Eunella Sullivanti, 601 Eunema, 514 Eunice, 423 Eunotiaamphioxys, 163, 164* ; gran- ulata, 163, 164*; Itevis, 163, 164*; tridentula, 163, 164*; zebrina, 163, 164* ; zygodon, 163, 164* Euomphalus, 520, 562, 586, 590, 598, 625, 642, 700, 704; alatus, 567; annulatus, 601 ; cyclostomus, 602 ; funatus, 568 Eupachycrinus, 690 Eupagurus, 59 ; longicarpus, 994 Eupelor durus, 751 INDEX. 1055 Euphantaenia, 432 Euphoberia, 691, 701 ; anthrax, T03 ; armigera, 678*, 691 ; Brownii, 703 Euphotide, 88 Euplectella, 482 ; speciosa, 57*, 432 Euproops Dana?, 691 Eupterornis, 925 Eurasia, 17, 21, 22, 32, 33, 51, 538 ; sea level at its center, 346 Eureka district, 447, 469, 478, 484, 495, 516, 541, 580, 581, 592, 593, 659, 733 ; mine, 340 ; quartzyte, 516 ; shale, 606 Mts., 733 Europe (see also Eurasia), 22, 28 (mean height), 24, 26, 32, 34, 41 (trends), 51, 165, 234 (snow-line), 296 (volcanoes), 393, 395, 398, 402, 403, 405, 406, 407, 411, 760, 793 (warmed by the Gulf Stream), 913 ; American types in, 550, 573 ; Australian types in, 922 , Archaean in, 442, 456 ; Cambrian, 484 ; Carboniferous, 631, 674, 689, 691, 692, 699 ; contrast of Juras- sic with American, 792 ; Lower Silurian, upturnings at the close, 533-535 Euryapteryx, 1014 Eurylepis, 679, 680, 692 ; tubercu- lata, 680*, 692 Eurynotus, 417 Eurypterids, 59, 420, 496, 565, 623, 719, 721 ; Devonian, 604, 615, 623*, 629, 719 (culmination) ; Car- boniferous, 676, 701, 710, 719 ; Lower Silurian, 496 (first), 521, 525, 719; Upper Silurian, 550, 571, 574; Onondaga, 556*, 557; Paleozoic, 420, 719, 723 Eurypterus, 557, 567, 615, 623, 722, 724 ; giganteus, 556 : Mansfieldi, 676, 677*, 710 ; prominens, 550 ; remipes, 556* Euryte, S4, 205 Eusarcus, 557 Eusthenopteron, 619 ; Foordi, 618* Eutaw beds (group), 815, 816, 819, 854 ; (Upper), 815, 823 Eutoptychus, 918 Everest (Mt.), 23 Evergreen trees, 435 Evolution. See also Life, progress of Evolution by Natural Selection, 1030, 1032 and cephalization, 439 Excavation by water, 167, 178 Excrements, fossil. See Coprolites Exmouth Isl., 749, 792 Exogens, 434, 435 Exogyra, 160, 779, 834, 840, 856, 860, 877 (end) ; arietina, 885*, 837 ; Boussingaultii, 867 ; columba, 866 ; columbella, 854, 855 ; conica, 865 ; costata, 841*, 854, 855 ; Couloni, 865 ; flabellata, 836 ; laevigata, 867 ; ponderosa, 834, 855 : sinuata, 837, 864, 865 ; sub- plicata, 867 ; Texana, 817, 836 ; virgula, 780* Exogyra arietina clays, 817 Exogyra ponderosa marls, 815, 824, 855 Expansion and contraction. 259-265, 372, 381 Exploits River channel, 461 Exploring Isles, 150 Extermination of species. See Life Extracrinus Briareus, 778*, 790 Facial suture, 421 Fagus, 896, 922 ; ferruginea, 895*, 896 Fairweather, Mt., 25, 238 Falkland Islands, 19, 155, 209, 627 Faluns beds of Anjou, 926 Famennian beds, 626, 627 Fanning Islands, 38 Faroe Islands, 938 Fasciolaria, 916, 922 ; buccinoides, 841* ; rhomboidea, 917 ; scalarina, 917 Fats (animal), 123, 124, 655, 656 Faults, 107, 108*, 109*, 110*, 111, 114*, 115*, 353; in the Great Basin, 365, 366* ; Taconic, 527* ; Appalachian, 354 Fauna antiqua Sivalensis, 936 Faunas. Seo Life Favistella, 552; favosidea, 550; stellata, 510, 511*, 515 Favosites, 310, 547*, 552, 562, 567, 581, 585, 597, 625, 640, 719 ; arbuscula, 601 ; Argus, 601 ; basalticus, 551, 591 ; Canadensis, 592 ; cervicornis, 562, 625 ; favosus. 550: fibrosus, 520, 522, 567, 568, 628; Goldfussi, 584*, 590 ; G^othlandicus, 550, 551, 552, 567, 568, 569, 591; Hamiltonise, 601 ; Helderbergia?, 560, 562 ; hemisphaericus, 592 ; Niagarensis, 547*, 55d"; placenta, 601 ; poly- morphus, 569 ; reticulatus, 623 ; turbinatus, 590 ; venustus, 550 Faxe chalk, 866 Fayalite, 67, 84, 338 Feature-lines, system in courses of, 35 Feldspar, 64*, 129 Feldspathic rocks, 80, 81, 82 ; veins, 331, 332, 336 Felis, 919, 927, 1001 ; atrox, 1000 ; leo, 1004 ; pardoides, 927 ; spelsea, 1004, 1006, 1009 Felsitic, 88 Felstones, 517 Felsyte, 82, 84 ; porphyry, 468, 623 Fenestella, 545, 546*, 551, 590 ; cel- sipora. 579 ; prisca, 546*, 550 Fermentation, 137 Fernandian, 446 Fernando de Noronha, phonolyte peak, 263* Fernando Po, 297 Ferns, 53, 434, 436 ; ash of, 74, 75, 663 ; Silurian, 564, 565 ; Devonian, 583*, 595* ; Subcarboniferous, 639, 645 ; Carboniferous. 654, 657, 666, 667, 670*, 671*, 676. 677, 682, 689 ; Permian, 684, 685, 704 ; Triassic, 740, 749*, 750, 770 Ferriferous limestone, 664, 792 Ferruginous clay, 81 ; rocks, 78 ; sandstone, 80 Fibrolite, 65, 66, 83 Fibrolitic rocks, 83 Fichtelgebirge, 563, 627 Ficophyllum, 831 Ficus, 831, 840, 916 ; auriculata, 839 ; lanceolata, 839 ; occidentals, 839 ; planicostata, 839 ; spectabilis, 839 ; tilisefolia, 839 ; Virginiensis, 832* Fig, 812, 859, 921 Fiji Islands, 145, 148, 150*. 297 Fin-spines, 416*, Findlay, Ohio, 533 ; oil-region, 138, 206, 522-523 ; yield of, 523 Finland, Archaean In, 455, 456; Lower Silurian, 521 Finsteraarhorn, 236 Fiords, 946-949 (Glacial) Fioryte, 82 Fire clay, 650 Fire-Hole, 305, 307 Firn, 233 Fish, primitive, related to the Lam- prey, 1031 Fish Creek Mts., 495, 733 Fish-oil in shales, 655, 656 Fish-scales, composition of, 73 Fisher Island, 822 Fishes, 52, 55, 56, 59, 60, 141, 146, 156, 158, 176, 409*, 414, 415-418, 564, 681, 789, 797, 931 ; fossil, in oil-yielding coal-beds, 124; reign of, 411, 460 ; earliest known, 509 ; culmination of, 869 ; first Teleosts, 73S Flabellaria, 921 ; eocenica, 839 Flabellina rugosa, 432*, 860* Flagellates, 419, 431 Flagging-stone, 92, 480 Flaming Gorge group, 747 Flamingoes, 923 Flammenmergel, 865 Flat-pebble conglomerate, 604, 630 Flathead Paver, 240 Flexure-faults, 109*, 351 Flexures, 99, 101*, 102*, 103*, 104*, 105*, 106*; variations in, from pressure, 369; in the Alps and Juras, 367, 368 .Appalachian, 354, 355*, 356*, 649*, 650* ; Taconic, 527* ; Wa- satch, 361, 369 Flies, 419, 794 Flint, 63, 97, 859 ; implements, 143, 1008 Flocculation, 170 Flood-grounds of rivers, 181, 182, 183, 191, 193-194, 943. See also Shore-platforms ; Terraces Flora. See Plants Florida, 22, 23 (height), 40 (trend), 153, 210, 213, 265, 323, 433, 823 ; coral reefs, 145, 153, 213 , Tertiary in, 881*, 884, 887, 890, 891, 892, 916, 934 (elevation) Banks, 163 seas, Nullipores in, 147 Strait, 44, 45, 229, 230, 256 Floridian epoch and beds, 884, 891, 900*, 917 1056 INDEX. Florissant group or basin, 886, 893, 900, 901, 902 Flotation crust, 378 Flow-and-plunge structure, 93*, 194 Flow of solids, 351-852 Flowerless plants. Bee Cryptogams Fluccan, 453 Fluidal structure in rocks, 77 Fluor-apatite, 73 Fluor spar. See Fluorite Fluorides, 69, 73, 143 Fluorine, 61, 63 Fluorite, fluor spar, 63, 69 Flustra, 427 Fluvial action, 744 ; formations, 191, 192, 820. See also Alluvial Flysch, 367*, 920 Folds. See Flexures Foliated rocks, 77, 309, 534 structure, foliation, 112, 113*, 312, 370-371 Folkestone beds, 865 Fontainebleau sandstone, 318, 926 Foosdiceras bidorsatum, 774 Foot wall, 328 Footprints (tracks, trails), 89, 95, 223; Cambrian, 446, 464, 469, 474, 477*, 479*, 480, 482 ; Upper Silurian, 544, 545*, 546*; Car- boniferous, 681, 682, 684*, 692; Subcarboniferous, 644, 645* ; Tri- assic, 742, 745, 750*, 751*, 752*, 753, 755, 772* Foraminifers, 57, 72, 432*, 454, 502, 840, 858, 860, 922 Fordilla Troyensis, 472* Forest bed, 927 Marble, 775, 790 Forests, 155 ; buried, 135, 887 Formation, 90 Formicidse, 901 Formosa, 40 Fort Benton group, 825, 829, 843, 855 Bridger, 886 Pierre group, 815, 825, 829, 830, 855 Tejon, 885 Union beds (group), 828, 830 Worth limestone, 817, 837 Fossil wood. See Wood, silicified Fossiliferous rocks, 309, 400, 408 Fossilization, methods of, 142 ' Fossils, 12, 71, 141 ; as means of correlation, 400^04 (precautions, 402-404), 405; distortion of, 107, 869, 370*, 371; obliterated by metamorphism, 314 ; silicified, 130, 135, 160, 323 Fox, 927 Fox Hills beds (group), 815, 825, 828, 829, 840, 842, 852, 855 Foyayte, 85 Fractures, 106, 107, 108*, 109*, 110* and displacements from pressure, 352*, 353*, 371, 807 ; from freezing water, 230, 231 ; from variations in temperature, 260 Fragillaria Harrisoni, 699 ; pinnata, 164*, 165 Fraginental deposits, 76, 89 France, 87, 167, 176, 297 (volcanoes), 734 (upturnings) , Archaean in, 456; Cambrian, 484; Lower Silurian, 518, 521; Upper Silurian, 564, 566, 568, 569, 573; Devonian, 626 ; Subcarbonif- erous, 693; Carboniferous, 693, 696, 702 ; Permian, 698 ; Triassic, 768, 769, 774 ; Jurassic, 774, 775, 792, 793 ; Cretaceous, 774, 856, 857, 859, 865, 866, 870; Tertiary, 919, 920, 921, 923, 924, 925, 926, 932 Franconia, 738, 769, 773 Franconian, 738, 769, 773 Franklinite, 70, 449 Frasnian shales and limestone, 626 Frasnian stage, 601 Fraxinus denticulata, 839 ; eocenica, 839 Fredericksburg epoch (group), 815, 817, 819, 836 Frederikshaab Glacier, 240, 241* Freeport coal, 652, 657, 663; lime- stones, 652 Freezing, effects of, 230 Freiburg vein, 333 French chalk, 67 Frenela, 922 Friendly Islands, 19, 20, 296, 392 Frigid zone, 46 Fringing reefs, 148*, 149*, 150*, 151 Frisco, Utah, 340 Frobisher Bay, 495 Frog, 54, 415, 418, 681, 795 Frog Mt., Ala., 577 Frog-spittle, 437 Frome group, 831 Frondicularia annularis, 432* Front Range of Colorado, 24, 25, 29, 203, 359, 363, 389, 580, 739, 747, 827, 829, 893, 935 Frost causing displacement, 157, 231* Fruits, Carboniferous, 668, 669*, 672*, 673*, 674; Subcarbonifer- ous, 639 ; Tertiary, 896*, 921 Fucoides Harlani, 549 Fucus, 75, 437 Fuegia, 154, 296; Cretaceous in, 858; snow line in, 234; glaciers on, 240 Fujiyama, volcano of, 290 Fulgur spiniger, 916 Fulgurite, 265, 266 Fuller's earth, 775, 790 Fumaroles, 82, 265, 293, 294 Fundamental Gneiss, 408, 440 Funeral Mountains, 23 Fungi, 75, 136, 158, 434, 436, 441, 454, 688 Fungoid plants, 63 Fusibility of igneous rocks, 273, 304; its degree determining the character of volcanic phenomena, 273, 274 Fusion, cooling from, 261*, 264 Fusispira elongata, 515; terebri- formis, 516; ventricosa, 515 Fusulina, 433, 659, 674, 696 ; cylin- drica, 432*, 674*, 690, 700 ; elon- gata, 690 ; gracilis, 690 ; Japonica, 700; robusta, 690; ventricosa,. 690 Fusus, 130, 916, 922; exilis, 917; interstriatus, 915 ; Labradorensis, 984; parilis, 917; pearlensis, 916 ; strumosus, 917 ; tornatus, 984 Gabbro, 87, 88 Gadolinite, 449 Gadus, 916 Galathea, 703 Galdhopig, 32 Galena, 70, 125 limestone, 342, 492, 494, 518, 514, 515, 522 Galeocerdo, 855 ; latidens, 926 Galerites, 860 Galerus, 916 Gait limestone, 543 Galveston Deep Well, 890, 891 Gambier Islands, 150 Gampsonyx fimbriatus, 701*, 703 Gangamopteris, 698 Ganges, delta of, 378 ; discharge of,. 173 ; silt of, 190 Gangue, 69, 70, 331, 333 Gannet, 902 Ganoids, 55, 59, 401, 402, 416, 417*, 418, 510 ; structure of teeth, 417*, 725; Trenton, 509 (first), 574; Upper Silurian, 574 ; Devonian, 587, 589*, 618*, 619, 620, 625*, 629 ; Subcarboniferous, 643, 700 ; Carboniferous, 679, 680*, 692, 698, 702; Permian, 687, 705; Paleo- zoic, 725, 727 ; post-Paleozoic, 736 ; Jurassic, 699, 783, 784* ; Mesozoic, 879; Cretaceous, 812, 828, 843,. 862, 863 ; Tertiary, 922 Ganorhynchus oblongum, 621 Gardeau shale, 605 Gardiners River, 131, 132* (springs),. 133, 306, 307 Garnet, 66* ; rocks, 82, 88 Garnetyte, 88 Garonne, 191 Gars. See Ganoid Garumnian, 859, 866 Gas, mineral. See Mineral oil and gas Gaspe, 88, 466, 533, 544, 554, 581,, 593, 611, 630 (upturnings) limestone, 544, 580 ; sandstones,. 591 Gaspe- Worcester trough, 536, 537,. 558, 559, 577, 633, 715, 732 Gastornis, 925 ; Edwardsi, 925 Gastrochsena, 157 Gastropods, 59, 130, 152, 157, 423,. 424, 425* Gault, 815, 818, 837, 857, 858, 859,. 865, 935 Gavialis Dixoni, 926 ; fraterculus,. 848 ; Neocesariensis, 848 Gavials, 54, 754, 787, 848 Gavilian Range, 892 Gay Head. See Martha's Vineyard G6ant, Glacier du, 235*, 236, 238, 242 Geanticline, Cincinnati. See Cin- cinnati uplift INDEX. 1057 Geanticlines, 106, 364, 381, 582; corresponding to geosynclines, 387, 892 Gedinnian, 570, 626 Gehlenite, 313 Gemellaria loricata, 427* Gemma purpurea var. Totteni, 917 Gems, 90, 327, 331 Genentomum validum, 691 Genesee beds, 594, 601 epoch, 410 Falls, section at, 91*, 542 Eiver, 540, 542, 605 shale, 581, 601, 728 ; slate, 593, 595 Geneva, Lake, 199, 202 Geode bed, 637 Geodes, 97, 98 Geodia, 432* Geodiferous limestone, 540 Geogenic work, 376 Geoglyphics, 95 Geographical distribution of plants and animals, 52-60 Geolabis, 918 Geoinys, 919 George's Shoal, 944 Georgia, 23 (height), 24, 184, 373 (earthquake), 872 Georgian Bay, 540 period, 464 Geosynclinal movements over the oceanic basins, 936-937 Geosynclines, 106, 199, 365 (Rocky Mts.), 380, 387 Geothermic, 257 Gerablattina, 691, 701 ; balteata, 686 Geralinura, 701, 723 ; Bohemica, 703 ; carbonaria, 691 Geraphrynus carbonarius, 691 Gerarus Dana?, 679* Germany, Paleozoic in, 463; Up- per Silurian, 563, 567 ; Devonian, 626, 627 ; Subcarboniferous, 693 ; Carboniferous, 693, 696, 703, 704 ; Permian, 697, 698, 707, 722 ; Trfassic, 741, 769, 773, 774 ; Ju- rassic, 774, 776, 793 ; Cretaceous, 774, 859, 865, 866 ; Tertiary, 920, 922, 923, 924, 925; volcanoes in Upper Silurian, 296 Gervillia, 759 ; acuta, 790 ; anceps, 865 ; bipartita, 774 ; costata, 773 ; longa, 690: socialis, 770, 771*, 773 Gervilliopsis ensiformis, 854 Geyser, water-and-gas, 607, 608* Geysers, 82, 265, 277, 291, 305*-309, 307*, 308* ; basins of, in Yellow- stone Park, 152, 305, 306* ; sili- ceous deposits from : geyserite, 64, 82, 152, 305, 306, 307; ter- races of New Zealand, 305* Giant geyser, 307* Giantess geyser, 307 Giants' Causeway, 261* Gibraltar, 131, 214 , Straits of, 20 ; currents at, 49, 229 Gieseckite, 84, 320, 453 Gila River, 885 Gilbert Islands, 36, 38, 39, 145 DANA'S MANUAL 67 Ginkgo, 485 ; adiantoides, 839 Giordanella, 482 Giraffe, 907 Giraffidfe, 927 Girvanella, 470, 502 ; ocellata, 501* Givet (Givetian) limestone, 626 Glabella, 420*, 421 Glacial period, 943 ; American, 943 ; migration of species caused by, 945 ; elevation of the land, 946 ; height of ice, 951 ; slope required for flow, 952 ; direction of flow, 952, 955; courses of scratches, 953; Driftless area, Wisconsin, 953 ; first Retreat, 961 ; final Retreat, 967 ; moraine, 900, 963* ; Kettle moraine, 967 .foreign, 975, 995; Asia, 977; Australia, 978; Europe, 975, 976* ; New Zealand, South Amer- ica, 978 climate, cause of, 978 ; supposed in the Triassic, 745 , map of N. America in, after page 944 conditions, in the Permian, 698, 737 Glaciers, 195, 200, 233; flow, 242; of Zermatt, 237* ; cascades con- nected with, 238 ; lakes, 238, 240, 251 Glanzschiefer, 84 Glass, 63, 77, 86, 264, 265 ; rela- tions of glassy rocks to stony, 276, 289 Glass sponge, 57*, 72 Glauber salt, 137, 294 Glauconite, 68, 136, 468, 822, 823, 824, 920 ; see also Green sand Glauconite group (beds), 815, 824, 855 ; marl, 865 Glaucophane, 89, 318 ; schist, 266 Glaucophanyte, 89 Gleditschia, 921 Glen Rose beds, 817, 836 Glimmerschiefer, 84 Globigerina, 57, 134, 144, 433*, 855, 935, 936 ; rubra, 432* Globigerina ooze, 144, 230, 433, 817 Globostellate spicule, 432* Globuliferous rocks, 83 Glossites, 621 Glossoceras, 551 ; desideratum, 573 Glossopteris, 698, 699, 704 ; Brown- iana, 698 Glossopteris Coal-measures, 698 Glycimeris reflexa, 917 Glyphaaa, 760 Glyptaster occidentals, 551 Glyptician, 790 Glypticus hieroglyphicus, 790 Glyptocardia speciosa, 612*, 620 Glyptocrinus, 520 ; decadactylus, 511*, 514, 516 Glyptodon, 1000, 1001, 1002; cla- vipes, 1003* Glyptolepis, 417, 625, 626; Que- becensis, 618* Glyptops ornatus, 766*, 767 Glyptostrobus Europseus, 921; Grrenlandicus, 833 Gnathodon tenuides, 837 Gneiss, 83, 122, 447 Gneissic quartzyte, 82 Gneissoid granite, 83, 227, 871 Gnetaceae, 435 Gnetum, 435 Gobi, Desert of, 32, 33, 51 Gorner Glacier, 237*, 248 Gornerhorn, 248 Gold-bearing veins, 338 ; washings. 170, 178 Gold Range, 739 Gomphoceras, 549, 561, 568, 586, 591, 599, 627; angustum, 551; eos, 516 ; oviforme, 602 ; parvu- lum, 561* ; Wabashense, 551 Gomphonema capitatum, 699 ; gra- cile, 163, 164* Gomphotherium, 918 Gondwana Land, 737, 873-874, 937 (period of existence) (Lower) series, 698, 770 (Upper) series, 769 Goniatite limestone, 576, 598, 637, 642, 647 Goniatites, 570, 575, 586* (first American), 593, 599, 700, 869 Goniatites, 568, 599, 613, 614, 625, 626, 642, 675, 686 ; bicostatus, 620 ; complanatus, .612, 620 ; dis- coideus, 586, 602, 620; intumes- cens, 614*, 620, 621, 627; Lyoni, 643* ; Marcellensis, 602 ; mithrax, 586*, 591 ; Oweni, 643* ; Pater- soni, 614*, 620 ; primordialis, 626 ; retrorsus, 626*, 627 ; sinuosus, 620 ; Vanuxemi, 599* Goniobasis, 828, 829, 856 ; convexa, 856 Gonioceras anceps, 514 Goniomya, 760 Goniophora, 621 ; Chemungensis, 621 ; perangulata, 601 Goniopteris, 685 ; arguta, 693 ; ele- gans, 693, 705; emarginata, 693, 705 Good-night beds, 885 Gordon-Bennett, Mt., height of, 296 Gorgonia, 55, 429*, 431 Gorilla, 54 Goro Island, 150 Gosiute Range, 365 Gothic Mountain, 274, 275* Gotland (Gothland), Lower Silurian in, 521 ; Upper Silurian, 564, 565, 568, 569 Grahamite, 662 Grallae, 923 Grammatophora marina, 437*, 894* Grammoceras, 760 Grammostomum phyllodes, 432* Grammysia, 602, 621 ; bisulcata, 598*, 602, 626; cingulata, 564*, 567, 573 ; communis, 621 ; Ham- iltonensis, 602, 626 ; subarcuata, 620, 621 ; triangulata, 573 Grampian group, 456 Granatocrinus, 646 Grand Bank of Newfoundland, 88 Canon. See Colorado Canon Chain, 732 Gulf group, 890, 891 1058 INDEX. Grand Manan Isl., subsidence of, 350 Portage Bay, 469 Granite, 82-83, 122, 205, 259 and mica schist, 448* Granitic rocks, 78 ; sediments, 744; veins, 314, 326, 329*, 331, 882*, 335, 386 Granitoid rocks, 77, 85, 86, 87 Granular limestone, 79 ; quartz, 82 Granulyte, 83 (kinds), 272, 316, 325, 371 Graphic granulyte, 83 Graphite, 62, 79, 83, 313, 319, 485, 714, 732; in Archaean, 453, 454, 455,458 Graphitic coal, 657 ; rocks, 79, 83, 449, 495, 518, 519, 658 Graptolites, 431, 470 ; Cambrian, 470, 474, 477*, 481 ; Calciferous, 497, 498*; Lower Silurian, 495, 504, 505*, 510*, 515, 520, 522, 525, 527, 718 ; Upper Silurian, 568, 574 ; Clinton, 545*; Lower Helder- berg, 560, 718 Graptolithus Clintonensis, 545*, 550 Graptolitic shales and slates, 518, 519, 520, 521, 568 Grasses, 435, 945 ; ash of, 73, 75 Grasshoppers, 419 Grauliegende, 697 Gravel, 75, 76 ; auriferous, 344, 810, 883, 887, 934 Gravitation theory of mountain- making, 381-383, 387 Gray band, 91, 542 wacke, 80, 408 Great Basin, 25, 119, 132, 195, 199, 444, 635, 658, 735, 739, 746, 748, 812, 818, 826, 882, 935 ; faults in, ranges. 365, 366*, 733, 789, 811, 934, 935 in the Quaternary, 988 System, 366 Great Bear Lake, 29, 200 Great Britain. See England Great Lakes of North America, 29, 40, 199, 200, 201*, 442 ; in Quater- nary, 947, 948, 986 Great Northeast Bay, 575, 683 Great Oolyte. See Oolyte Great Salt Lake, 25, 51, 120, 153, 199, 200, 202, 362, 382, 444, 826, 881, 882, 988 ; valley, 361 Great Slave Lake, 29 Grecian Archipelago, 296 Greece, Pikermi beds of, 927 Green earth, 68 Green Mts., 24, 41, 326, 467, 490, 528, 531, 536, 541, 945 (Arctic plants) Green Eiver basin, 882, 893 epoch or group, 365, 886, 901, 918 Green sand. See Green sand shale of the Clinton, 542 Greenland, 19, 40, 233, 234 (snow- line), 236, 239, 240, 249*, 251, 252, 256, 272, 820, 337, 347, 376, 395 ; fiords, 240, 241, 948 ; glaciers, 240, 241*, 244, 251, :941 ; map of western, 241* ; subsidence, 349, 350 Greenland, Archaean in, 444; Car- bonic, 711 ; Cretaceous, 794, 819, 831, 833, 837, 838, 839, 840, 868, 872 (climate), 873 ; Tertiary, 819, 921, 939 ; Glacial, 945, 948 Greensand, 68, 136, 191, 468, 477, 820, 821, 822, 824, 858, 887, 888. See also Glauconite Greenstone, 86, 449 Greisen, 82, 83 Grenville limestone, 454, 493 Grenzdolomit, 774 Gres Armoricain, 518 bigarre, 769 de Fontainebleau, 205, 920 des Vosges, 769 Gresslya donaciformis, 791 Greylock (Mt.), 104, 495, 530* Gries Glacier, 243 Griffith Isl., 495 Griffithides, 643, 676, 700; Sanga- monensis, 691 ; scitulus, 691 Grindelwald Glacier, 233, 238 Grindstones, 80 Grinnell Land, 369, 606, 635, 663 Grit, 80 Grizzly Bear, 950 (migration) Groovings. See Scratches Ground-ice, 232 Ground-pines. See Lycopods Groups, 406 Grus proavus, 1002 Gryllacris lithanthraca, 704 Gryphsea, 759, 779 (time range), 792, 834, 840, 860 ; arcuata, 779, 790 ; bilobata, 790 ; Bryani, 854 ; cal- ceola, 760; convexa, 854; dila- tata, 779, 780*, 790, 819 (var. Tucumcari) ; forniculata, 836 ; incurva, 779* ; mucronata, 817, 887 ; mutabilis, 854 ; obliqua, 790 ; Pitcheri, 817, 835*, 836, 837, 841*, 854 ; sublobata, 790 ; vesi- cularis, 841*, 854, 855, 866 ; vir- gula, 791 Gryphaea beds, 790 ; rock, 836 Gryphaeostrea vomer, 854 Guadalupe Mts., 660 Guanaco, 54 Guano, 63, 72, 73, 153 (analysis), 887 Guatemala, 168 Guelph limestone, 543, 549, 551 Guiana, 31 Guinea, 33 Gulf of Bothnia, 521 of California, 30, 51, 145, 200 of Carpentaria, 39 of Finland, 521 of Guinea, 295 of Mexico, 18, 20, 44, 45, 49, 190, 191, 198, 217, 462, 483, 573. 794, 814, 827, 834, 857, 881, 934 '(Ter- tiary), 940, 949 ofPenjinsk, 927 Stream, 44, 48, 49, 55, 56, 144, 166, 229, 230, 256, 524 (Cambrian), 792, 793, 872 Gutenstein, 769, 774 Guyot Glacier, 238 Gymnites incultus, 774 Gymnoptychus, 918 Gymnosperms, 434, 674, 718, 750 ; Neopaleozoic, 460 ; Hamilton, 595, 596; Chemung, 610,612; Subcar- boniferous, 639 ; Carboniferous, 666, 667, 672*, 673, 674, 689 Gymnotoceras rotelliforme, 757 Gypidula occidentalis, 602 Gypsum, 69*, 128, 138; how formed, 554 ; on coral islands, 120 ; in the Salina, 553, 554, 555* beds of Montinartre, 923 Gyroceras, 591, 599, 642; Burling- tonense, 642 ; Jason, 591 ; trans- versum, 602 ; undulatum, 591 Gyrodescrenatus,854; petrosus,854 Gyrodus, 417 ; umbilicus, 417* Gyrolepis, 772 ; tenuistriata, 774 Haddock bones, analysis of, 78 Hade, 107, 328 Hadrosaurus, 846 ; Foulkii, 845 Haiti, 347, 891 & 985 (Miocene), 936 Haleakala, Mt., 270, 277, 290, 291, 346, 379 (density) Halemaumau, 269*, 271, 285, 291 Halicalyptra fimbriata, 433* Halisarcoids, 431 Halitherium, 927 Halloceras, 591 Hallopus, 786 Hallstadt limestone, 774 Halobia, 756, 757, 774 ; dubia, 757 ; Lommeli, 757, 758, 792; occiden- talis, 758 ; ZitteH, 792 Halobia bed, 757 Halodon sculptus, 853* Halonia, 699; pnlchella, 668*, 669, 688 Halysites, 310, 541, 547*, 551, 552, 567, 568 ; agglomeratus, 550 ; catenulatus, 514, 515, 516, 520, 522, 544, 547*, 550, 551, 552, 567, 568, 569; escharoides, 550; gracilis, 510, 511*, 515 ; interstinctus, 567 Hamilton period, 592 Haminea grandis, 916 Hamites, 760. 867 : alternatus, 865 ; attenuatus, 862*, 865; elatior, 867 : Fremonti, 836 Hanging wall, 328 Hannibal shales, 637 Haploceras, 760, 794 Haploconus, 917 Haplophlebium, 679 Hard-pan, 128, 205 Harding sandstone, 495, 515 Harlania Halli, 545*, 549 Harpes, 515, 520, 521, 551, 568, 625; antiquatus, 503 Harpides, 521 ; Atlanticus, 573 ; rugosus, 573 Harpoceras, 794; bifrons, 790; M'Clintocki, 792; Murchisonse, 790 ; radians, 790 ; serpentinum, 790 Harttia Matthewi, 475* Harz Mts., 87, 563, 567, 569, 626, 697, 734 Hastings sands (and clays), 858, INDEX. 1059 Hatchetigbee beds, 888 Hatteras. See Cape Hatteria, 54, 68T, 706, 798 Hauynite, 88 Hauptdolomit, 774 Hauterivian, 859, 865 Hawaii, 213, 282, 269*; map of, 268*, 269, 270 , volcanic action on, 268*, 269*, 372, 379 Hawaiian Islands, 36* (map), 51, 145, 150, 163, 324, 350, 392 Hawkesbury sandstone, 698, 770 Hawthorn beds, 891 Haystack Mt., 937 Headon beds (series), 926 Heard Island, 241, 242 Heat, 253; earth's interior, 257; from chemical and physical changes and mechanical action, 258 ; from crushing, 322, 326 ; from interior sources, effects of, 260, 381 ; in mines, 339 Heath, 945 Heavy spar, 69 Hebrides, 218; Archaean in, 456, 867 Hecla mine, 339 Hecla Mt., 241, 286, 305 Hedgehog, 54, 427, 930 Helaletes, 907, 918 Helderberg Mts., 543, 553, 555, 561, 579 Helderberg, Lower, 558 , Upper, 579 Helena Canon, 515 Helicina occulta, 966; orbiculata, 966 ; profuuda, 966 Helicoceras, 861 ; Mortoni, 855 ; Navarroense, 855 Helicopsyche, 60 Helicotoma, 516 ; planulata, 507*, 514 Heliolites, 521, 550, 552, 567; inter- stinctus, 520, 522, 550, 568; porosus, 626, 628; pyriformis, 550, 568 ; spiniporus, 547*, 550 Heliophyllum, 581, 611 ; confluens, 601; Halli, 590, 597*, bOl, 611, 625 ; obconicum, 601 Heliosphsera, 319 Heliscomys, 918 Helix, 425*; Cuperi, 966; fulva, 966; labyrinthica, 926; lineata, 966 ; occlusa, 926 ; pulchella, 966 ; striatella, 966 ; Turonensis, 926 Helix family, 690 Hell Gate, 211 Helminths, 423 Helodus, 644, 702 Helohyus, 918 Helvetian group, 926 Hemapedina, 779 Hematite, 70, 71, 83, 123, 126, 127, 449, 450, 453, 539, 665 Hemeras, 407 Hemeristia occidentalis, 691 Hemiaspis limuloides, 565*; spe- rata, 567 Hemiaster, 834, 840; parastatus, 854; Eegulusanus, 866; Texanus, 855 ; Verneuili, 866 Hemicidaris, 779 ; intermedia, 790 ; Purbeckensis, 791 Hemicystites, 516 Hemipristis serra, 917 Hemipronites punctuliferus, 562 ; radiatus, 562 Hemipsalodon, 918 Heinipteroids, Carboniferous, 691, 702 ; Paleozoic, 721, 722 Hemipters, 419, 520, 525, 574, 756, 900 Hemitrochiscus paradoxus, 707 Hemitrypa, 579 Hempstead beds, 926 Henry Mts., 301, 876 Hepatic*, 434, 436 Heptodon, 918 Herbivores, 902, 929, 930, 981 Herculaneum, 280 Hercynian beds, 564; fauna, Kay- ser's, 569; Question, Clarke's, 569-570 Hercynian system, Bertrand's, 734 Herring, 862, 879, 901 Hervey Islands, 36, 37, 350 Hesperomys, 919 Hesperornis, 852, 864, 871 ; regalis, 850*, 852 Heteraster oblongus, 865 Heteroborus, 925 Heteroceras, 855 Heterocercal, 401, 402, 416 Heterocrinus, 516, 532; Canadensis, 514, 516 ; geniculatus, 516 Heteromyaries, 525 Heteropods, 506 Heteroschisma, 601 Hettangiau, 774, 790 Hexacoralla, 777, 860 Hexactinellids, 57, 431, 432*, 497, 498*, 504, 611, 639, 646, 777*, 860 Hexameroceras delphicolum, 551 Hexaprotodon, 927 Highland Range, 443, 469 Highlands of N. J. and of Putnam Co., N.T., 24, 443, 530, 531, 745 Highwood Mts., 876 Hilo, 295 Hils formation, 865 Himalayas, 26, 32, 41, 234, 365, 379, 392 Archaean in, 456 ; Silurian, 521 ; Jurassic, 776, 791 ; Tertiary, 347, 365, 892, 920 ; changes of level in, 932, 933, 936, 938; Quaternary, 392, 936; glaciers in, 239, 240; upturning and elevation of, 368*, 936 Himantidium arcus, 163, 164*; Monodon, 163, 164* Hindeastrsea discoidea, 840* Hindia, 562, 584, 590 Hindostan, 22 Hindu-Kush, 32, 41 Hipparion, 919, 927 Hipparionyx, 578 ; proximus, 579 Hippidium, 919, 1002 Hippopodium ponderosum, 790 Hippopotamus, 54, 906, 925, 927, 928, 930 ; major, 927, 1004, 1006 ; Pentlandi, 1006 Hippotherium, 927 ; ingenuum, 1001 Hippurite limestone, 836, 859, 866 Hippurites, 866, 877 (end) ; brevis, 866; Corbaricus, 866; dilatatus, 861*, 866; floridus, 866; gigan- teus, 866 ; organisans, 867 ; Petro- corriensis % 866; socialis, 866 ; Tou- casi, 866 ; Toucasianus, 861* Hoang Ho, 30, 195, 196*, 198 Hoei Ho, 198 Hog, 906, 910, 911, 930 ; family, 909, 924, 928, 930 Holaspis, 625 Holaster, 840, 860; Isevis, 866; nodulosus, 865 ; planus, 866 ; sim- plex, 837 ; subglobosus, 866 ; sub- orbicularis, 866 Holectypus planatus, 837 Holometopus Angelini, 573; lim- batus, 573 Holonema, 617 ; rugosum, 616*, 618, 621 Holopea, 499*, 514, 521, 562; an- tiqua, 558 ; dilucula, 499* ; elon- gata, 558 ; subconica, 558 ; Sweeti, 478* ; turgida, 501 Holopella, 520; conica, 567; gre- garia, 567 ; obsoleta, 567 Holops pneumaticus, 848 Holoptychius, 417, 510, 618*, 619, 625*, 626, 702 ; Americanus, 621 ; filosus, 621 ; giganteus, 621 ; hor- ridus, 621 ; nobilissimus, 627 ; rugosus, 621 Holothurians, 423 Holothurioids, 427 Holy Cross Mt., 250 Holy Island, 156 Holyoke Mt., 802, 803 Homacanthus gracilis, 591 Homacodon, 918 ; priscus, 906 Homalonotus, 422, 520, 521, 546, 562, 570, 578, 579, 586, 591, 599, 626; Dawsoni, 562; delphino- cephalus, 549* 550, 551, 567, 569 ; Knightii, 567, 573; major, 578; Vanuxemi, 570 Homewood sandstone, 656 Homo diluvii testis, 921 Homocercal tails of fishes, 417 Homocrinus, 562 Homotaxial, 398 Ho-Nan, 198 Honduras, 20, 747, 756 Honesdale sandstone, 606 Hood Mt., height of, 296 ; glaciers of, 240, 945 Hoogly, mouth of the Ganges, 212 Hoplites auritus, 865 ; Deluci, 865 ; Deshayesi, 887, 854, 864 ; Desori, 867 ; dispar, 867 ; interruptus, 865 ; lautus, 865; Noricus, 865; radia- tus, 865 ; splendens, 865 Hoplolichas, 591 Hoplophoneus, 918 Hoplophorus, 1003 Horizonality of strata, 98 Horn-silver, 840 Hornblende, 66, 67* andesyte, 86, 892; granite, 82, 88, 85 ; picryte, 88 .pyroxene, and chrysolite rocks, 1060 INDEX. Hornblende schist, 85 Hornblendyte, 88, 325, 532 Hornstonel 82, 540, 579, 580, 584, 646, 859; in Corniferous, with Protophytes, 582, 583* Horse, 54, 55, 907, 908, 911, 912, 914*, 927 type, evolution of, 912, 913*, 929, 931 Horse in a vein, 330 Horse-shoe crab, 420 Horse-tail. See Equiseta Horsetown beds, 815, 818, 820, 831, 837 Horton series, 639 Hosselkus limestone, 757 Hot springs, 121, 135, 137, 152, 265, 277, 305, 306, 313, 320, 323, 343 ; analyses of waters, 121 ; life of, 60, 152, 308, 454 ; superficial vein- making at, 334 Housatonic River, 227*, 325 House Range, Utah, 494 Hualalai Mt., 268*, 269 Huamampampa sandstone, 628 Hudson Bay, 29, 40, 442, 541, 552, 883, 947, 948, 949 Hudson - Champlain trough, 537, 572 Hudson epoch, 510 River, 212, 216, 528, 529*, 530, 537, 540, 541, 558, 579, 628, 734, 743, 744, 745; submarine chan- nel, 18*, 745, 949; valley, 357, 552, 558, 559, 579, 605, 982 Huerfano group, 893 Human bones, analysis of, 73 Humboldt Glacier, 241; Ranges, 365, 733, 811, 812, 945; region, 746, 757, 760 Humite, 67 Humming birds, 54, 55 Humus acids, 119, 122, 124, 125, 128, 129, 139 Hunan, 696 Hungary, Archaean in, 455 ; Upper Silurian, 573 ; Tertiary, 938 Hung-tse Lake, 198 Huron, Lake, 200, 201*, 445, 449, 452, 493, 533, 540, 542, 552, 553, 572, 592. 635, 947 Huron Cupriferous Formation, 445 River, 947 shale, 606 Huron ia, 549 ; Bigsbyi, 551 ; verte- bralis, 551 Huronian, 407, 445, 446, 447, 448, 449, 450, 451, 453, 454, 458, 466, 468, 488 Hurricane fault, 363*, 747 Hyaena, 927 ; crocuta, 1004 ; spelaea, 1004, 1006, 1009 Hyaenarctos, 927 Hyaenocyon, 918 Hyaenodictis, 925 Hyaenodon, 918, 926 ; dasynroides, 924 ; leptorhynchus, 926 Hyalina arborea, 966 Hyalomicte, 83 Hyattella congests, 546*, 550 Hybocrinus, 514 Hybodonts, 415, 416*, 643, 644*, 647, 772 Hybodus, 772 (first), 783; minor, 416*, 772 ; plicatilis, 416*, 772, 774 Hydnoceras, 646 Hydra, 429*, 430 Hydration, 128 Hydraulic cement, 79, 80, 555; limestone, 79, 555, 592 Hydrocarbon, 62, 74, 124 Hydrocephalus, 482 Hydrochloric acid, 68, 278; from volcanoes, 278, 294 Hydrogen, 61, 62 ; from volcanoes, 278, 287, 293, 294 sulphide, 119, 124, 125, 523, 554 Hydroids, 140, 419, 430, 547*, 560 Hydromica, 65, 83, 318 ; granite, 82 ; quartzyte, 82 ; schist, 80, 82, 84 Hydrotalcite, 453 Hydrozoans, 140, 418, 419, 429*, 430*, 431 Hyena, 54 Hylajosaurus Oweni, 863 Hylerpeton, 682 Hylonomus, 682, 706 Hymenocarids, Upper Cambrian, 488 Hymenocaris vermicauda, 481* Hymenophyllites, 645, 689; Gers- dorffi, 622 ; Hildrethi, 670*, 689 ; obtusilobus, 622 ; spinosus, 689 Hymenopters, 419, 679, 783, 794, 900 (number of Florissant) Hyodectes, 925 Hyolithellus, 471, 472 ; micans, 472* Hyolithes, 447, 471, 478, 481, 482, 514, 562, 599, 621 ; Acadicus, 475* ; Americanus, 471, 472* ; Danianus, 475* ; gregarius, 478* ; impar, 472* ; levigatus, 482 ; ligea, 590 ; princeps, 472* Hyomeryx, 918 Hyopotamus, 918 ; bovinus, 926 Hyopsodus, 918 Hyperodapedon, 772 Hypersthene, 67, 86, 87, 88 Hypertragulus, 918 Hyperyte, 87 Hypisodus, 918 Hypnum, 154 Hypogeic work, 118, 345-896 Hypogene rocks, 311 Hyposaurus Rogersi, 848; Webbii, *848 Hypostome, 421 Hypsilophodon Foxi, 863 Hyrachus, 907 Hyrachyus, 918, 923 Hyracodon, 910, 918 ; Nebrascensis, 910* Hyracops, 917 Hyracotherium, 913*, 918, 923, 925 Hyrax, 54, 55 Hystricops, 919 Hystrix, 927 Ibis, 928 Ice (see also Glaciers ; Water, freezing), 231, 282; glacier, 243, 846 ; plasticity, 243, 244, 245 I Ice, effects on lakes, rivers, and sea- coasts, 232 ; fractures from tor- sion, 371, 372* Iceberg theory of the drift, 942 Icebergs, 241, 251-252; transporta- tion by, 217, 230, 252 ; transported by the Labrador current, 229, 239 Iceland, 19, 48, 256, 286, 297 ; gey- sers, 82, 305, 307 ; Sequoia of, 939 ; volcanoes of, 297 Ichthyocrinus Isevis, 547*, 550 Ichthyodectes, 862 Ichthyopterygians, 760 Ichthyornis dispar, 851* ; victor, 851*, 852 Ichthyosarcolithus anguis, 836 ; crassifibra, 836 ; planatus, 836 Ichthyosaurs, 792, 797 ; Jurassic, 760, 761, 790 ; number of British, 784 ; Triassic, 774 Ichthyosaurus, 749, 773, 790 ; corn- munis, 784* ; Nordenskioldi, 792 ; polaris, 792 Icla shales, 628 Ictops, 918 Idaho, 23 (height); Cambrian in, 477 ; Calciferous, 501 ; Subcarbon- iferous, 639, 647; Triassic, 746, 747, 757 ; Jurassic, 747, 760 ; Ter- tiary, 938 Idocrase, 66, 313 Idonearca vulgaris, 854 Igaliko, Firth of, 350 Igneous action and its results, 265 ; exterior agencies, 265 ; volcanoes, 267; non-volcanic eruptions, 297 ; thermal waters, geysers, 305 ejections and intrusions, 89, 258, 364, 882, 383, 658, 811 ; great in the later part of geological time, 392, 441 ; surficial, 299, 300* ; veins made by, 338-343 fusion, source of, 804 phenomena due to exterior agencies, 265, 266 rocks, 67, 76, 80, 272-274 and metam orphic, relations of, 326-327 Iguana, 863 Iguanavus teres, 849 Iguanodon, 786, 828, 845, 856, 863, 865 ; Bernissartensis, 863* ; Man- telli, 863* Ilex, 854 ; cassine, 74, 75 Ilfracombe group, 625 IlLenus, 500, 502, 508, 520, 521, 546, 551, 568 ; Arcturus, 503 ; Bay- fieldi, 503 ; Bowmani, 520 ; cras- sicauda, 515 ; Davisi, 519* ; globosus, 503 ; loxus, 549, 551 ; Taurus, 515 ; Thomsoni, 567 Illawarra, 261* Illicium, 896 Illinois, mean height of, 28 ; up- lifts in, 732 ; lead mines, 842, 522 Illinois River, 948 Ilmen Mts., 85 Ilmenite, 70, 87 Ilyanassa obsoleta, 994 Ilyodes, 691 India, 32, 34, 160, 299, 846, 406; united with S. Africa, 871, 873, 893 INDEX. 1061 India, Archaean in, 466 ; Cambrian, 483 ; Upper Silurian, 564 ; Car- boniferous, 632, 693 ; Permian, 686, 698, 699, 737, 770 ; Triassic, 632, 698, 737, 769, 770, 773, 791 ; Jurassic, 698, 776, 791, 873; Cre- taceous, 299, 833, 857, 866, 867, 873, 874, 876; Tertiary, 299, 920, 923, 925, 927, 936, 938 Indian Ocean, 17, 19, 23, 31, 33, 43, 44, 50, 296, 297, 632, 937, 939 ; top- ographic changes in, 737 Indian Territory, Cretaceous in, 817, 836 Indiana, 23 (height), 207, 357 ; min- eral gas and oil in, 206, 522, 523, 607 ; yield, 523 Indianaite, 638 Individualities in nature, 9 Indrodon, 917 Indus Basin, alluvial cones of, 195* delta, earthquakes of 1819 and 1845, 349 , valley of Upper, 368 Infra-Cretace, 865 Infra-Lias, 774 Infusorial earth, 81 , 895; Tertiary, 894*, 895 Ink-bag of Belemnite, 782* Inocaulis arbuscula, 516 Inoceramus, 759, 760, 834, 837, 840, 860, 867, 877 (end) ; biformis, 855 ; concentricus, 865; confertim-an- nulatus, 854; Crispii, 855, 867; Crispii var. Barabini, 854; de- formis, 855; digitatus, 866; di- midius, 841*; exogyroides, 855; fragilis, 855; labiatus, 840, 841*, 854, 855, 866; latus, 854, 867; raytiloides, 867 ; problematicus, (= I. labiatus), 841* ; proximus, 854 ; striatus, 866 ; sublsevis, 855 ; subquadratus, 855 ; substriatus, 790 ; sulcatus, 865 ; tenuicostatus, 855 ; tenuilineatus, 855 ; umbona- tus, 855 Inoperculates, 54 Inorganic distinguished from or- ganic, 9, 413 Insectivores, 54, 768, 902, 903, 906, 907, 911, 918, 925, 927, 928, 929, 930 Insects, 54, 72, 141, 154. 158, 163, 189, 418, 419, 520; derivation, 723-724 ; relations to other articu- lates, 724 ; tracks, 95, 742 ; Lower Silurian, 496, 521, 525; Upper Si- lurian, 574, 721 (first) ; Devonian, 575, 600*, 601; Subcarboniferous (none), 643; Carboniferous, 657, 674, 677, 679*, 691, 692, 701*, 704; Permian, 686 ; Paleozoic, 525, 721, 727 ; post-Paleozoic, 736 ; Triassic, 742, 750*, 751, 756, 757, 771, 794 ; Jurassic, 775, 776, 783*, 791, 794 ; Tertiary, 202, 887, 893, 900*, 901, 921, 922, 923 ; Glacial, 946 Integripallial, 425 Interior Continental region, 34, 199 of N. Amer., 348, 387, 580, 581, 590, 592, 593-594, 606, 714, 715, 716, 856, 944 ; of Europe, 533, 573, 627, 693, 769, 775, 867 Interior plains, 24 Intestinal worms, 423 Invertebrates, 404, 414, 418; rela- tion of, to Vertebrates, 418; reign of, 460 locrinus, 516 ; crassus, 514 Iodine, 331, 835 lolitic granite, 83 lone formation, 892 Iowa, height of, 23 ; uplifts in, 782 ; lead mines, 342, 522 Iowa-Texas Coal-measure region, 648 Iphidea bella, 471* Ireland, 203; disturbances, 534; eruptions, 258, 518; peat-beds, 154 , Archsean in, 456 ; Cambrian, 480, 481, 482, 534 ; Lower Silurian, 518, 534; Upper Silurian, 563, 574; Devonian, 622, 626 ; Subcarbonif- erous, 694, 695 ; Carboniferous, 693, 704; Permian, 697; Creta- ceous, 856 ; Tertiary, 938 Irish Deer, 927 Iron, density of, 15; oxidation of, 123; carbonate, 81, 125; oxides, 62, 124 ; sulphate, 70 ; sulphides, 70, 80, 123 age, 445 ore (and ore beds), 69, 70, 92, 127, 315, 326, 327, 344, 391 ; Archaean, 376, 445, 446, 449*, 450, 451, 453, 454, 455, 456, 458 ; Cambrian, 446 ; Lower Silurian, 524 ; Clinton, 539, 542, 543, 572, 728 ; Carboniferous, 650, 651, 652, 656, 663, 664-665, 708 ; Jurassic, 792 sandstone, 542 Iron Mts., 444, 449 Ironstone, 344, 688 Irrawaddy, ratio of sediment to water, 190 Isastrsea, 777, 778 (number of Brit- ish) ; discoidea, 854 ; explanata, 790 ; Murchisoni, 790 ; oblonga, 777* Ischadites, 562 ; bursiformis, 590 Ischyromys, 918 Ischyrosaurus, 856 ; antiquus, 829, 856 Isectolophus, 918 Isis nobilis, 72 Island Range of British Columbia, 739, 747, 809 Islands, chains of, 20, 374 ; curves in, 35*, 36*, 37*, 39* as parts of continents, 22 ; of British Columbia, 390 Isle of Wight. See Wight Isle Royale, 483 Isocardia Conradi, 854; fraterna, 917 ; medialis, 836 ; Washita, 837 Isocrymal chart, 46, 47* Isopods, 420*, 421, 422, 438, 439, 487, 512, 623, 624, 720, 723, 783 Isoseismic curves, 375 Isostasy, 377, 378, 379, 382, 875 Isotelus canalis, 503 ; platycepha- lus, 508* Isothermal chart, 46, 47* Itabyryte, 83 Itacolumyte, 82 Italy, 296 (volcanoes) ; Subcarbon- iferous in, 693 ; Carboniferous, 693 ; Triassic, 768 ; Jurassic, 793 ; Oolyte, 309; Cretaceous, 857. 859 ; Tertiary, 921, 926, 927, 938 (eruptions) Ithaca group, 603, 604, 605, 614, 620, 629 Ithygrammodon, 918 lulids, 419 lulus, 676 Ixtaccituatl, Mt., height of, 937 Jackson coal, 657 epoch, 884, 889, 907, 916 Jakobshavn Glacier, 244 Jamaica, 29, 163, 347, 891, 935, 936 James River, 816 Jan Mayen, 19, 297 Janassa bituminosa, 707 Janira occidentals, 836; Wrightii, 837 Japan, 19, 22, 32, 40, 183, 277, 280, 290, 293, 296, 297 ; earthquakes of, 373, 374 ; Carboniferous, 696, 700 ; Tertiary, 920 Japan Sea, 927 Jasper, 82, 84, 309, 450, 453, 454 Java, 38, 40, 277, 297 (volcanoes), 920 Jeanpaullia Munsteriana, 756; ra- diata, 756 Jeff Davis Peak, 945 Jefferson Mt., 240 (glacier), 296 Jelly-fish, 430 Jet, 775 Joaquin River, 30 Jock coal-bed, 656 Joggins Coal-measures, 654* (sec- tion), 658, 682, 690 John Day beds, 884, 886, 894, 911, . 918, 926 John Day River, 886, 894 Johnstown cement-bed, 652 Joints, 111, 112*, 371-572, 598 Jokuls Fiord, reconstructed glacier, 242 Joliet building-stone, 541 Jolleytown coal-bed, 651 Joplin lead mines, 522 Jordan valley, 23 Jorullo (Mt.), 27 Judith River beds, 828, 829, 847, 850,856 Juglans, 921 ; denticulata, 889 ; rhamnoides, 839 ; rugosa, 889 Jukes Butte, 301* Juncus, 75 Jungfrau, 236, 237 Jupiter, density of, 16 ; oblique lines on, 395 Jupiter Serapis, 349 Jura limestone, 738 Jura Mts., 207, 382; Triassic in, 768 ; Jurassic, 738, 774, 798 ; Cre- taceous, 859 ; Tertiary mountain- making, 367, 368* (section), 919, 932 Jura-Trias, 738, 749, 770, 881 ; of Elk Mts., 864* 1062 INDEX. Jurassic period, 738, 739, 758, 774, 857, 873 ; foreign, 774 Justedal Glacier, 251 Juvavites, 757 Kaibab fault and fold, 362, 868* Kainozoic. See Cenozoic Kalium, 61 Kamchatka, 40 ; volcanoes of, 296 Kames, 970 Kampecaris Forfarensis, 625 Kanab Canon, 581 Kanawha Salines, 689 Kangaroo, 415 Kansas, 23 (height), 842 (lead mines) ; Paleozoic in, 342 ; Car- boniferous, 130, 665, 674, 678, 690, 691 ; Permian, 660 ; Cretaceous, 813, 817, 819, 826, 829, 843, 848, 849, 850, 851, 852, 864, 872, 873 ; Tertiary, 885 Kaolin (kaolinite), 68, 81, 134, 295 Karharbari Coal-measures, 698 Karoo beds, 698, 699, 737, 770, 778 Kashmir, 32, 770 Kaskaskia group, 634, 637, 646 Kauai, 36, 283, 290 Kea, Mt., 27, 179, 268*, 269, 270, 276, 290, 291 ; density of, 379 Keeling atoll, 20 Keewatin, 466 Kellaway beds, 777 Kellaways rock, 775, 790 Kelp, 155 Kenia, or Kenya, Mt., 88, 977 Kennedy Channel, 495, 559 Kenodiscus Schmidti, 773 Kent Belt of limestone, 529*, 580 Kent-Cornwall ridge, Conn., 449, 531 Kentucky, 23 (height), 387; cav- erns, 130 (length), 137, 207 ; min- eral oil, 609; Cincinnati beds, 504, 692; Cincinnati uplift of, 387, 490, 532 Kentucky River, 503 Keokuk group, 634, 637 ; limestone, 97, 138, 342, 638, 644, 646, 647 Kerguelen Land, 296 (volcanoes) Kermadec Islands, 37 Kersantyte, 86 Kettle holes, 970, 992, 993* Keuper, Keuperian, 411, 788, 769, 771, 772, 773, 774 , Lower, 755, 771 Keupermergel, 769, 774 Keweenaw, Keweenawan, Kewee- nawian, Keweenian, 447, 464 copper region, 341, 342, 466, 468, 483 group, 445, 447, 465, 468, 469, 488, 484 Point, 465 Key West, 168 Khingan Mts.. 82 Kiama, 281 ; basaltic columns, 261*, 262* ; dike with outflow, 262* Kiamitia clays, 817 Kicking Horse Pass, 26, 469, 495 Kilauea, 178, 268*, 269*, 270, 271, 272, 276, 277-283 (passim), 284*, 285*, 286*, 288, 291, 293, 295, 308 Kilima-Njaro, Mt., 83; height of, 296 Killinite, 821 Kimberley shale, 770 Kimmeridge clay, 411, 775 Kimmeridgian group, 775, 776, 779, 780, 790 Kinderhook group, 634, 687, 638, 646, 647, 709 King William's Island, 495, 524, 544, 552 Kingdoms of nature, 9 Kingfisher, 54, 852 Kingsmill Islands. See Gilbert Islands Kionoceras laqueatum, 500* ; strix, 551 Kittanning coal-beds, 652, 663, 664, 688 Mts., 538, 539 ; valley, 857 Kiusiu Island, 277 Klamath Mts., 659, 747, 809 Knobstone group, 637, 638 Knorria, 610, 639, 645, 689, 698, 699 ; acicularis, 626, 699, 704; imbri- cata, 645, 689, 699, 704 Knox dolomyte, 468, 493 ; sand- stone, 468 Knoxville beds, 760, 815, 818, 820, 831, 837 Kossen beds. 769, 774 Kohala Range, Hawaii, 269 Kohlenkeuper, 769 Koipato group, 747 Koko Head, Oahu, 271* Kome group (beds), 819, 883, 888 Kong Mts., 33 Kootanie beds (group), 815, 818, 819, 820, 833, 834, 868, 872 Pass, 818 Kotzebue Sound, 240, 640, 1003 Krakatoa volcano, 163, 291 Kuen-Lun Mts., 26, 82 Kuhn Islands, 776 Kupferschiefer, 697, 707 Kurile Islands, 19, 296 (volcanoes), 297 Kutorgina, 480, 481, 486 ; cingulata, 471*, 480, 573 ; Labradorica var. Swantonensis, 480 Kyanite. See Cyanite Labradioryte, 86, 825 ihyric, 77 'ador, 350, 442, 944 (precipita- ;ion), 948 (fiords) ; Cambrian in, 467 current, 45, 48, 55, 166, 229, 230, i, 873 LaWdorian, 446 LabiWite, 64, 65, 77, 85, 86, 87, 88, 273^295, 311, 318, 319, 320, 328, 324, 325, 442 Labrosaurus, 766 Labyrinthine structure of teeth, 417*, 725 Labyrinthodonts, 417*, 796 ; Coal- measure, 772 ; Permian, 869 ; Tri- assic, 772*, 869 ; Cretaceous, 870 Laccadive Islands, 145 Laccolite, 301 Laccoliths, 296, 301*, 802, 803, 845, 383, 469, 804, 806, 807, 876 Lacerta, 787 Lacertians, 787, 848 Lacustrine areas, Tertiary, 202, 365, 882 beds (deposits), 76, 191, 202; Quaternary, 985, 986, 988 limestone of Beauce, 926 Ladrones, 19, 20, 37 ; volcanoes of, 296 Laelaps aquilunguis, 847 ; incrassa- tus, 847 . Laevibuccinum lineatum, 915 Lafayette beds (group), 888, 890, 892 formation, 964 Lagomys spelsetus, 1006 Lagrange group, 885, 891, 896 Lahontan region, 119, 133 Lake Agassiz, 985 Bonneville, 988 Cham plain, 982 Lahontan, 988 of the Woods, 200, 446 Warren, 987 Lakes, Great, elevated shore lines of, 986. See Great Lakes Lakes, 166, 198, 201* Lambdotherium, 918 Lamellibranchs, 424, 425* Laminarians, 56 Laminated rocks, 80, 309; struc- ture, 92 Lamna, 144, 863; compressa, 855; elegans, 416*, 901*, 925, 926; Texana, 843*, 855 Lampreys, 418 Land, arrangement of, 16, 21 ; be low sea level, 22, 23 ; in one hem isphere, 16* ; mean height of, 23 ; ratio of, to water, 16 Land-shells, 54 Landenian group, 925 Land's End, 317 - Landslides, 208, 232 Langhian group, 926 Lanthanum, 449 Laodon venustus, 767* Laopithecus, 918 Laopteryx, 768 ; priscus, 768 Laosaurus censors, 765* Lapilli, 267 Lapland, 234 (snow-line) ; Archaean in, 456 ; Cambrian, 484 La Plata (Rio de la Plata), 24, 80, 171, 191 (ratio of sediment to water) ; Cretaceous of, 867 Laramide Range, 382, 383, 389, 891, 483, 572, 581 ; Mountain System, 359*-364, 375, 380, 383, 398, 391, 406, 874*-876, 882, 883 Laramie beds, 824, 826, 827, 828, 846, 847, 850, 852, 856, 870, 873, 880, 893 (Upper), 815, 821, 825, 827, 828, 829, 830, 856, 873, 875 Mts., 748 Plains, 747 Lasiograptus mucronatus, 510* Lassens Peak, 87, 296, 749, 987 Laumontite, 68 INDEX. 1063 Laurentian, 445 , the Champlain period, 941 Laurentide Mts., 445 Laurus, 837, 840, 854, 921, 922; socialis, 839 Lauteraar Glacier, 237, 248 Lauzon group, 496 Lava, 76, 85, 267, 272, 275 conduit, 277 ; cones, conditions determining their forms, 274-276 ; stalactites and stalagmites, 294*, 295, 324 streams, 287*-291, 293, 294, 295 Layers, 76, 91, 92 (structure) Lead mines, Illinois and Wisconsin, 342, 522 ; Missouri, 342, 522 ; New York, 542 ; Kocky Mtn. region, 876 Leadville mines, 340, 341*, 343; region, 304, 342, 876 Leaia tricarinata, 691 Lecanocrinus, 550 Leclaire limestone, 543 Leda, 602, 621, 917 ; amygdaloides, 925; arctica, 984; mater, 916; minuta, 983, 984; multilineata, 916; ovum, 790; pernula, 983, 984 ; truncata, 984 Leech, 423 Leiocidaris hemigranosa, 837 Leiopteria, 621 ; laevis, 602 Leiorhynchus limitare, 602, 612 ; mesacostale, 612, 620, 621 ; quad- ricostatum, 612*, 620 ; sinuatum, 621 Leitha limestone, 926 Lemberg chalk, 866 Lemuravus, 918 Lemuroids, 917 Lemurs, 54 Lena River, 30 Lenticular mass, 92* Lepadocrinus, 562 ; Gebhardi, 562 Lepas family, 600 Leperditia, 481, 509, 516, 517, 562, 567 ; alta, 556*, 557 ; amygdalina, 503 ; Anna, 499* ; Argenta, 476, 477* ; armata, 515 ; Baltica, 552, 569 ; Cambrensis, 481 ; Canaden- sis, 502*, 503, 515 ; dermatoides, 474* ; fabulites, 508*, 515 ; Key- serlingi, 568 ; nana, 502* Lepidodendrids, 664, 684, 698, 712, 718, 750 Lepidodendron, 610, 611, 627, 628, 639, 645, 654, 658, 667*, 668*, 689, 698, 699, 704 ; aculeatum, 645, 646, 668*, 688, 689 ; acuminatum, 646 ; Chemungense, 609*, 610 ; clypea- tum, 668*, 688, 689 ; corrug'atum, 611, 645; costatum, 645; dicho- tomum, 645, 688, 689 ; diplostegi- oides, 645; forulatum, 645; Gaspianum, 583*, 595, 611, 622; lanceolatum, 669* ; modulatum, 688, 689 ; obovatum, 645, 689 ; obscurum, 645 ; primaevum, 595*, 601, 610 ; rimosum, 689 ; squaino- sum, 699; Sternbergii, 668, 688, 689 ; tetragonum, 645 ; turbina- tum, 645 ; Veltheimanum, 626, 645, 668*, 688, 689, 699, 704; vestitum, 689 ; Wortheni, 645 Lepidomelane, 65 Lepidophloios, 689, 699 ; laricinus, 689 Lepidophyllum, 668, 699 Lepidopters, 419, 679, 900 Lepidosiren, 54, 417, 418 Lepidosteus, 59, 73, 417*, 901, 926; osseus, 417* Lepidostrobus, 645, 668 ; hastatus, 669* Lepidotus, 783 Lepidoxylon, 673 Lepisma, 419, 702 Lepta-na, 503, 520, 521, 562, 568, 579; laticosta, 626; Murchisoni, 626 ; rhomboidalis, 507*, 514, 520, 548*, 551, 562, 567, 568, 572, 590 ; sericea, 503, 507*, 514, 520, 521, 522, 524, 550 ; transversalis, 503, 568 ; Verneuili, 568 Leptauchenia, 918 Leptictis, 918 Leptocardians, 414, 418 Leptochoerus, 918 Leptocladus, 789 Leptocoelia, 579, 627 ; flabellites, 579 Leptodesma, 620, 621 ; lichas, 618* ; spinigerum, 621 Leptolepis, 699 Leptomeryx, 918 Leptomitus Zittelli, 470* Leptophlreum, 590 ; rhombicum, 622 Leptophractus obsoletus, 682 Leptosolen biplicata, 854 Leptostrophia, 579; Becki, 579; perplana, 579 Leptotragulus, 907, 918 Leptynyte, S3 Lepus, 918 Lesleya, 639 Lessonia, 155 Lestosaurus, 848 ; simus, 849* Lette Island, 296 Lettenkohle, 755, 769, 774 Leucite, 65, 77, 81, 85, 86, 88, 273, 274; rocks, 81, 85 Leucitophyre, 85 Leucitophyric, 77 Leucityte, 86 Leucotephryte, 85 Leucozonia biplicata, 915 Levant series, 728 Level, changes of, now in progress, 348, 349*, 350 Level of no strain. See Zero strain Levis formation, 490, 496, 497, 527* Lewis Island, 456 Lewisian Gneiss, 440 (Archaean synonymy) group of Murcbison, 456 Lherzolyte, Liard River, 746, Lias (Liassic), 77"5; in Western America, 808, 809 , White, 774, 790 Liassian of D'Orbigny, 775 Libellula, 783* ; Brodiei, 783 Liberty Cap, geyser cone, 807* ! \ 46, 738 ), 775; in Libocedrus, 939 ; decurrens, 939 Lichas, 520, 521, 551, 561, 568, 586, 591 ; Anglicus, 567 ; Bigsbyi, 561 ; Boltoni, 549*, 551 ; cucullus, 515 ;. grandis, 586, 587* ; gryps, 587* ; hylaeus, 587* ; laxatus, 567 ; pus- tulosus, 561; Ribeiroi, 521; Trentonensis, 508*, 509, 512, 515 Lichenocrinus, 516 Lichens, 58, 75 (ash), 126, 136 (ash), 436, 688, 946 Life, characteristics of, 9, 413 ; its chemical work, 136-137 ; contribu- tions to rock-making, 71-75; de- structive effects of, 157 ; protec- tive effects, 155 ; transporting ef- fects, 156 , disappearance of, 403, 404 ; at close of Mesozoic, 876-877; at close of Paleozoic, 727, 728, 735- 736 ; at close of Cretaceous, 576 , evolution by variation, 1020 , general laws as to progress in, 1028; geographical distribution of, 52-60 ; injury to, from mineral and marine waters, 122 ; introduc- tion of, 397, 458 , lowest species the best rock- makers, 142 ; mechanical work and rock contributions, 117, 118, 140-158 , oceanic, distribution of, illus- trated by the physiographic chart, 47* , system of, animal kingdom, 413; vegetable, 434; cephaliza- tion, 437 Ligerian, 859, 866 Light affecting life, 52 Lighthouses and waves, 217, 218 Lightning, effects of, upon rocks and sand-heaps, 265, 266 ; heat of, 258 Lignite, 816, 817, 819, 821, 825, 829, 830, 887, 890, 922 Lignitic beds, 828, 829, 885, 887 (Brandon), 889, 895, 896, 921, 922 Ligumen planulatum, 854 Ligurian group, 884 Lily Encrinite, 770 Lima, 756, 757, 75\ 780, 834, 860 ; crenulicosta, 854 ; decussata, 866 ; gigantea, 779*, 790; Kimballi, 837; proboscidea, 791; punctata; 791; retifera, 690; rudis, 790; Shastaensis, 837; striata, 774; Taylorensis, 759* Limacina, 424 Limbs. See Merosthenic; Podos- thenic ; Prosthenic ; Urosthenic Limestone, 62, 78-80 ; ferriferous, decaying to limonite, 126* ; meta- morphic, 309, 310, 315; rate of formation, 716 ; teachings of coral reefs on, 151 caverns, 883 Limnadia, 486 Limnsea, 152; caudata, 926; desid- iosa, 966 ; humilis, 966 Limnophysa desidiosa, 966; hu- milis, 966 1064 INDEX. Limnopus vagus, 684* Limnoria, 158 Limnosyops, 918 Limonite, 71 ; from decaying fer- riferous limestone, 126* Limulids, Paleozoic, 676, 701*, 719 Limuloids, 419, 420, 423, 455 ; deri- vation, 720-721 Limulus, 59, 420, 496, 556, 565, 616, 676, 720, 721, 724 ; polyphemus, 420 Lingula, 59, 72, 73 (composition of shell), 425*, 468, 481, 487, 493, 496, 516, 521, 550, 606, 612, 621, 719 ; acuminata, 500 ; cuneata, 538, 544*, 549 ; Huronensis, 503 ; lamellata, 551 ; lata, 567 ; Lewisii, 567; Lyelli, 503; minima, 567; nitida, 840 ; ovalis, 73 ; quadrata, 507*, 514, 516; spatulata, 612*, 620 family, 779, 840 (Mesozoic and Paleozoic contrast) flags, 481, 489, 573 Lingulella, 425, 481, 482; ccelata, 471* ; Davisi, 481*, 520 ; Dawsoni, 475* ; ella, 471* ; ferruginea, 481 ; lowensis, 515; prima, 478*; pri- mseva, 481 Lingulepis antiqua, 478* Lingulocaris, 482 Linnarssonia pretiosa, 500 ; trans- versa, 475* Linton, Ohio, fossils, 661, 679, 681, 682, 692 Liochlamys bulbosa, 917 Liodon, 864 Lion, 54 Lipari, 276 Liquidambar, 921, 922 Liriodendron, 837, 921 ; Meekii, 837, 838* ; simplex, 837, 838* Lisbon, earthquake, in 1755, 373 Lisbon beds, 889 Listriodon, 927 Lithia, 61, 321 Lithia Well, Ballston, 121 Lithic era, 440 Lithistids, 777, 860* Lithium, 61, 335 ; salts, 119 Lithobius, 724 Lithodesare, 59 ; Agassizli, 59 Lithodomous shells, 348 Lithodomus, 157 ; praelongus, 867 Lithographic limestone, 637, 646, 776, 788 Lithoidyte, 84, 337 Lithomantis carbonaria, 702 Lithomylacris, 691 Lithophis, 901 Lithophysae (lithophyses), 289, 337, 338 ; of Obsidian Cliff, 337*, 338 Lithosphere, 61 Lithostrotion, 640, 659, 674, 700, 711, 718; Canadense, 639*, 640, 646; mammillare, 659 ; proliferum, 646 Lithostrotion beds, 688 Litoceras, 501 Litssea Weediana, 889 Little Ararat, 265, 296 (height) Elko Range, 866 Metis, Can., 497, 500 Little Missouri River, 266 River group, N. S., 593 Littoral and abyssal deposits com- pared, 151 currents, 212 ; zone, 56 Littorina, 130 ; palliata, 984 Lituites, 499, 511, 520, 521, 567, 568 ; Americanus, 573 ; Ammo- nius, 511 ; Farnsworthi, 500 ; giganteus, 567, 573 ; imperator, 499, 500 ; Marshi, 551 ; undatus, 514 Lituola nautiloidea, 432*, 860* Liverworts, 436 Livingston beds, 828, 839, 875 Lizards, 54, 415, 768, 787, 849 Llama, 54, 910, 924, 1002 Llandeilo group, 463, 515, 519, 568 Llandovery group, 518, 520, 534, 567, 569 Llano Estacado, 912 Llano group, 447, 469 Loa, Mt., 26, 27, 179, 268* 269* 270, 275, 276, 279, 286*, 288, 304 Loam, 76 Lob-worm, 156, 420*, 423 Lobster, 78, 420, 421, 438, 717, 771, 783 Locusts, 419, 677, 679 Lodes, 327, 331 Loess, 81, 152, 195, 196* Loess, of the Mississippi, fossils in, 964, 966, 973 Loftusia Columbiana, 674, 690 Loganellus, 503 Loganite, 454 Loganograptus Logani, 498* Logs, 156, 189, 191 ; carbonized at one end and silicified at the other, 143 ; in the Coal-measures, 654 ; see also Wood Loire River, peat marsh of, 154 Loligo vulgaris, 424* Lombardy, 769, 774 London, 17 London basin, 920, 923, 925; clay, 920, 923, 925 London-Paris basin, 857, 919, 920, 936 Lone Mountain, 495; limestone, 516, 733 Long Island, 18*, 41, 162, 167, 205, 206, 211*, 223, 224, 225, 350 ; ori- gin of north bays of, 949 ; clay- beds, 822, 823, 837, &39 ; drift, 942 - , Archaean of, 444 ; Cretaceous, 822, 823, 839, 872 ; beds upturned during the Tertiary, 934, 1022*; Glacial, 949, 960, 962, 964, 970 Sound, 18*, 211*, 226*, 227, 444, 461 ; a river channel in the Glacial period, 949 ; tides of, 211, 214, 215, 216, 226 Longmynd rocks, 480, 534 Lonsdalia, 718 Loochoo Mts., 40 Loon, 852 Lophiodon, 923, 924, 925 ; minimus, 926 Lopholatilus, 56 Lophophyllum, 674 ; proliferum, 674 Lorraine, 738, 792 Lorraine shales, 489, 494 Los Carlos Mts., 340 Louisiade Islands, 36, 38 Louisiana, mean height of, 28 Louisiana limestone, Missouri, 687 Loup Fork beds, 829, 884, 885, 886; fossils of, 894, 895, 911, 919 Low-lands, 23 Lower California. See California Lower Helderberg period, 558 , Devonian relations of fauna, 569-570 Lower Silurian era, 489 Lowlands, 28 Loxoinma Allmanni, 703 Loxonema, 520, 562, 590, 599, 618, 621, 625, 642, 700 ; priscum, 601 ; semicostatum, 690 ; sinuosum, 567 Loxotrema, 916 Loyalty Islands, 36 Lucia Island, 881 Lucina, 602, 780, 867, 916; ano- donta, 917 ; Claibornensis, 916 ; contracta, 917 ; cribraria, 917 ; occidentalis, 855 ; Portlandica, 791 ; serrata, 926 Ludian beds, 926 Ludlow beds, 463, 563, 578 Lumachelle limestone, 792 Lunatia, 916; Grcenlandica, 983, 984 ; heros, 983, 984 ; obliqua, 854 Lung fishes, 417, 587, 618 Lunulicardium, 602, 621 ; acutiros- trum, 620 ; fragile, 612*, 620 ; or- natum, 620 Lutetian group, 925 Lutraria papyria, 916 Luzon, 40, 920 Luzula, 240 ; hyperborea, 945 Lychnocanium lucerna, 438* Lycopodites, 610, 668 Lycopodium chamsecyparissus, 75; clavatum, 74; complanatum, 75; dendroideum, 75, 668, 669 ; selago, 946 Lycopods, 58, 74, 75, 434, 436, 663, 667, 668, 672, 711, 712, 713; ash of, 74, 75 ; spores, composition of, 713 ; Clinton, 549 ; Corniferous, 583*; Hamilton, 595*; Subcar- boniferous, 639, 645; Carbonif- erous, 666, 667, 668* Lyell (Mt.), glaciers of, 240, 945 Lykens Valley coal, 656 Lynton group, 625 Lyre bird, 54 Lyria costata, 898*, 916 Lyrodesma, 516 ; cuneatum, 567 Lytoceras, 760, 793, 794; Batesii, "*837 ; Jurense, 790 Macacus, 55 McGregor coal-bed, 658 Machaeracanthus sulcatus, 589* Machaerodus, 911, 919, 927, 1000; Floridanus, 1001 ; latidens, 1006 Mackenzie River, 40, 171, 859, 580, 590, 592, 593, 594, 602, 830 Laramie area, 827 Mackerel, 812, 862 Mackinac, 552, 580, 628 INDEX. 1065 ^Maclurea, 493, 499, 516, 51T, 520; arctica, 525 ; cuneata, 515 ; Logani, 502* ; magna, 491, 502*, 503, 514, 524, 525; matutina, 500, 517; subrotunda, 515 Maclurea limestone, 494 Macoma calcarea, 984 ; fragilis, 983, 984 ; fusca, 984 ; sabulosa, 983, 984, 995 Macquarie Islands, 37, 39 Macrauchenia, 1002 Macrocheilus, 599, 621, 642, 700; fusiformis, 675*, 690 ; Newberryi, 690 ; ventricosus, 690 Macrochilina subcostata, 601 Macrocyclis concava, 966 Macrocystis pyrifera, 156 Macrodon, 621 ; carbonarius, 675*, 690 Macropetalichthys Sullivanti, 588* Macropterna divaricans, 752* Macropus, 1006 Macroscopic texture, 76 Macrostachya, 699 Macrotheriura, 918, 925 Macrurans, 52, 59, 421 , 438, 439, 615, 701*, 707, 720, 771*, 783* Mactra alta, 855; delumbis, 917; ovalis, 983 Madagascar, 296 (volcanoes), 737, 873 Madeira, 297 Madison River geysers, 305, 307 Madrepora palmata, analysis of coral of, 72 Maestricht beds, Maestrichtian, 815, 858, 859, 864, 866, 870 Magellan, Straits of, 858, 867 Magellania, 426* ; flavescens, 426* Maggiore, Lago, 199 Magnesia, 61 .Magnesian limestone, 78, 131; Cambrian, 468 ; Lower Silurian, 491, 493, 501, 732 salts, of the ocean, 320 .Magnetic iron (magnetite), 70, 170, 223, 578 Magnetitic rocks, 83, 84 Magnolia, 812, 837, 840, 859, 921 Magothy formation, 819 ; River, 819 Mahoning sandstone, 652, 656 .Maine, 23, 85, 158, 160, 265, 461; fiords of, 444, 948 ; upturnings in, 630, 732 , Archaean in, 444 ; Paleozoic, 461 ; Cambrian, 466 ; Lower Silurian, 493 ; Niagara, 539, 541, 544, 552 ; Clinton, 539, 552 ; Lower Helder- berg, 544, 552, 558, 559, 562; Oriskany, 577, 579 ; Devonian, 622, 630 ; Glacial, 948, 949 Maine- Worcester trough, 461 Malacca, 22, 38, 41 Malachite, 342 Malaspina Glacier, 238, 239* Maldive Islands, 145, 150, 787 Maleri beds, 773 Mallotus villosus, 984 Malm, 776 Malocystites Barrandi, 503 ; Murchi- soni, 502*, 503 Malta, 921 Mammals, geographical distribu- tion, 54, 409*, 414; relation to Amphibians, 726, 794, 795, 796; increase in size of brain during the Tertiary, 913, 914; reign of, 878, 879 ; Triassic, 754*, 773, 797 ; Jurassic, 767*, 789* ; Cretaceous, 852, 871 ; Tertiary, 902, 920, 923, 927 ; evolution of Eocene, 928 , Tertiary and Quaternary, rela- tions of, 1017 .Quaternary, 950, 997; culmina- tion of, 1016 ; degeneration in some Quaternary species of, 1007 Mammoth coal-bed, 650, 652, 653, 656, 660, 663 Man, 1008 ; relation to Quadru- mana, 1017, 1036; Pleistocene, 1008 ; origin, 1036 Man-apes, 54, 1036 Manasquan group, 821 Manatus, 925 Manchuria, 32, 696 Mangaia Island, elevation, 350 Manganite, 71 Mangrove, 155 Manis, 54 Manitoba, rainfall in, 944 ; Trenton in, 515 ; Lower Helderberg, 561 ; Devonian, 594, 597, 601, 602 ; Cre- taceous, 830, 856 ; Glacial, 945 Manitoba (Lake), 594 Manitou Park, 876 Manitoulin Islands, 522, 540, 542 Mantellia, 777 ; inegalophylla, 776*, 777 Manteodon, 918 Manti beds, 893 Mantle, 425 Map of Apia and Menchikoff, 145* , bathymetric, 17, 19, following 20* (bathymetric) of submerged At- lantic border, 18* of the Atlantic coast-region, 224* of Mont Blanc glaciers, 235*, 236* of Triassic area of Connecticut, 801* of harbor at mouth of Connecti- cut, 226* , geological, of England, 693, 694* of Fiji Islands, 150* of the Great Lakes, 201* of western Greenland, 240, 241*, 249* of Hawaii, 268* of Hawaiian Islands, 36* of harbor at mouth of Housa- tonic River, 227* of land and water hemispheres, 16* of Long Island Sound, Long Island, and the Atlantic Border, 17, 18*, 211* of Loyalty group, 85* of Marquesas Islands, 36* of Mars, 396* of Maui, 179* of delta of the Mississippi, 197* of New Caledonia, 35* of New Haven harbor, 226* Map of trap dikes, near New Haven, 299* of New Hebrides, 35* of part of eastern New York and western Connecticut, 529*, 530 , geological, of North America, 412*, 635 of North America after the Ap- palachian revolution, 734, 735*, 739 of North America in the Ar- chaean, 442, 443* of North America at the com- mencement of the Carbonic era, 633* of North America in the Creta- ceous, 812, 813*, 814 of North America, Glacial, illus- trating the phenomena, after 944 of North America, Tertiary, 881*, 883 of North America, Upper Silu- rian, 535, 536*, 575, 633, 634 of Oahu, 292* of courses of Pacific island chains, 37*, 39* , topographical, of Pennsylvania, 357, 729, 730*, 731 of Pennsylvania coal-fields, 649* of courses and flexures of ridges in central Pennsylvania, 729, 731* of Mt. St. Elias region, 239* of Tahitian Islands, 36* of Tahiti, 180 of United States, 412*, 799 of Wasatch Mts. and Utah, 360* of ti,p world, on M creator's pro- jection, 17, 47* , physiographic, of the world, 46, 47*, 350 of Yellowstone Park, 306* Maple, 837, 859, 879 Marble, 76, 79*, 131 Marble Canon, 186, 187*, 862, 363* Marcasite, 70, 123, 125, 126, 258, 331, 342, 663 Marcellus epoch, 410, 576; shale, 576, 593 Marcy, Mt., 452 Mareniscan, 446 Margaric acid, 124 Margarita Nebrascensis, 841*, 855 ; striata, 984 ; varicosa, 984 Margaritana margaritifera, 950 Margarite, 320 Margaritella, 916 Margaritina confragosa, 966 Marginella, 917 Mariacrinus, 577 Mariposa region, 748, 760, 837 Marl, 68, 79 ; Tertiary, 820, 854 Marlstone, 411, 775 Marly clay, 81 Marlyte, 552, 553 Marmot, 156 Marquesas Islands, 297, 850; map of, 36*, 38 Marquette iron region, 445, 446, 450 Marquettian, 446 1066 INDEX. Mars, density of, 16 ; oblique feat- ure-lines on, 395, 396* Marsh gas, 124, 523 Marsh ore, 71, 344, 455. See also Bog ore Marshall group (grit and sand- stone), 638 Marshall Islands, 395 Marsilea, 718 ; quadrifolia, 436* Marsileacese, 519 Marsipobranchs, 418 Marsupials, 53, 54, 55, 415. See Mammals Marsupiocrinus caelatus, 567 Martha's Vineyard, Cretaceous of, 822, 837, 838; Tertiary of, 881; 891 ; upturning of beds, 934, 1022 Maryland, mean height of, 23; Cambrian in, 465, 466, 467 Mascarene Islands, 787 Massachusetts, 23 (height), 85, 453, 496; coal-beds, 634, 646, 657; iron ore beds, 127 ; kaolin beds, 134 ; marbles, 524, 530, 531 ; Cam- brian in, 310, 466, 467, 471, 475; Taconic, 491, 517, 524, 528, 530, 531 ; Trenton, 495 ; Triassic, 740, 741, 742, 750, 753, 800, 802 Bay, 444, 461, 536 Massawipi Lake, 558 Massillon coal, 657 Massive limestone, 76, 78 ; quartz- yte, 82 ; rocks, 76, 78 ; struc- ture, 92 Mastodon, 919, 927, 1000, 1011 Americanus, 998* ; Arvernensis 927; angustidens, 927; Borsoni 927 ; Floridanus, 1001 ; longiros tris, 927 ; mirificus, 911, 912 proavus, 911 ; tapiroides, 927 Mastodons, 141, 402, 911 (first), 924, 925 ;odonsaurus giganteus, 772* ; Jaegeri, 774 Mastogloia, 164*, 165 Matheria variabilis, 478* Matinal of Eogers, 490, 494, 728 Matterhorn, 189, 237 Matthews' Landing clays, 885, 888 Mauch Chunk group, 410, 634, 636, 644, 728 Maudunian group, 925 Maui, 150, 172 ; map of, 179*, 182 ; cone of, 270 Maumee Eiver, 947 Mauritius, volcanoes of, 277, 296, 1019 Mauvaises terres, 894 May-fly, 419, 600 May Hill sandstone, 518, 563. 566, 569 Mayencian group, 926 Mazonia Acadica, 691 ; Woodiana, 691 Mazzalina pyrula, 916 Meadville group, 638 Medina epoch, 535, 570 sandstone, 538, 542 Mediterranean Cretaceous basin, 857, 859, 872, 873; earthquakes of, 374; region, 769, 791, 793, 861 Sea, 20, 21, 22, 34, 45 ; tempera- ture of, 49 ; salinity of, 121 ; vol- canoes of, 295 Medlicottia Copei, 685*, 686 Medusae, 55, 418, 419, 429*, 430. 479, 480, 482 Medusites, 482 Meekella Shumardana, 685 ; striato- costata, 690 Meekoceras aplanatum, 757 Megadactylus, 753 ; polyzelus, 753 Megalaspis, 521 Megalichthys, 621, 692, 702 Megalocnus rodens, 1001 Megalodon triqueter, 774 Megalomus Canadensis, 548*, 551 Megalonyx, 912, 919, 1000, 1001, 1003 ; Jeffersonii, 1000, 1001* ; Leidyi, 1001 Megalopteris, 689 ; fasciculata, 645 Megalosaurs, 786, 828 Megalosaurus, 765, 766, 790 ; Bredai, 864 ; Bucklandi, 785 (time range) ; Dunkeri, 863 Megambonia, 562 Megaphyton, 699; McLayi, 669*, 689 ; protuberans, 645 Megaptera longimana, 983 Megathentomum, 679 ; pustulatum, 691 Megatheridse, 1000 Megatherium, 1000, 1002, 1004; Cuvieri, 1002* ; mirabile, 1000 Megistocrinus, 590, 602 Meionite, 65 Meizoseismic curve, 375 Melania costata, 926 ; fasciata, 926 ; inguinata, 925 ; turritissima, 926 Melantho subsolida, 966 Melaphyre, 87 Meleagris altus, 1002 ; celer, 1002 Melocrinus, 550, 562, 577 ; Clarki, 621 ; nobilissimus, 560 Melongena crassicornuta, 916 Melonites multiporus, 641*, 646 Melosira distans, 163, 164* ; granu- lata, 163, 164*; decussata, 163, 164*; Marchica, 163, 164*; sul- cata, 437*, 894* Melville Island, 659, 689 Memphremagog (Lake), 531, 580, 591, 630 Menaccanite, 70 Menacodon rarus, 767* Menchikoff Island, 145*, 150 Mendip Hills, 695 Mendoza earthquake, 349 Menevian group, 481 Menilite, 920 Meniscoessus conquistus, 852 Meniscotherium, 917 Meniscus limestone, 543, 550 Menobranchus lateralis, 682 Menocephalus, 503 Menominee, 446 Menurids, 54 Merced group, 884, 892 Mercer coal-beds, 656 Mercian, 631, 738 Mercury, density of planet, 16 Mercury mines of California, 835 Meretrix, 916 Meridian series, 728 Merista, 642 ; plebeia, 625, 628 Meristella, 562, 579, 642 ; angusti- frons, 567; didyma, 567; Isevis, 560*, 562; nasuta, 590, 591, 592; subundata, 520; sulcata, 557> 560* ; tumida, 568 Meristina nitida, 548*, 551 Merjelen (Lake), 238 Merocrinus, 516 ; typus, 514 Merosthenic, 717, 796, 870, 871 Merychyus, 919 Merycochcerus, 918, 919 Merycopotamus, 927 Mesa, 185, 186*, 300 Mesabi Kange, 446 Mesalia Claibornensis, 897*, 916;; obruta, 916 ; vetusta, 916 Mesnard, 446 Mesodectes, 918 Mesodevonian, 576 Mesodon albolabris, 966; diastema- ticus, 836 ; Dumblei, 836 ; pro- fundus, 966 Mesohippus, 908, 912, 913*, 918 Mesonacis Vermontana, 473* Mesonyx, 918 Mesoreodon, 918 Mesosaurus, 706 ; tumidus, 687, 688* Mesothyra Neptuni, 600; Oceani, 600, 615* Mesozoic time, 738 Messinian group, 927 Metacoceras cavatiforme, 690; dubium, 691 ; Hayi, 691 ; incon- spicuum, 691 ; Walcotti, 691 Metadiabase, 86 Metadoxides, 482 Metagene, 880 Metalophodon, 918 Metals heavier than iron not erup- tive, 876 ; native, 331, 332 Metamorphic rocks, 76, 82 and igneous, relations of, 326, 327 Metamorphism, 309 ; dynamical, began in the Archseozoic era, 441 ; , heat in, 311, 321-326; local, 311, 312-314; metachemic, 314, 318-- 321; moisture in, 311-312; para- morphic, 314, 317-318 ; regional, 311, 313, 314-315 ; statical, began in the Lithic era, 440; without, heat, 327 in Archfean, 448, 450, 451, 453 Metamynodon, 918 Metapedia Lake, 533 Metasomatic metamorphism, 314 Meteoric stones, 11, 876 Meteorites, 376, 486 Metia Island, 133, 151 (height), 350' Metoptoma, 482, 514, 516 ; alta, 501 ;. dubia, 503 Meudon chalk, 866 ; marls, 925 Meuse, ratio of sediment to water, 190 Mexico, 25, 26 ; snow-line in, 234 ; volcanoes, 296, 937 ; mines of, 338, 340; height of Cretaceous beds, 933 ; Archaean in, 444 ; Car- boniferous, 537, 569; Permian, 659 ; Triassic, 739, 747, 755 ;, INDEX. 1067 Jurassic, 749 ; Cretaceous, 364, 813*, 814, 817, 818, 820, 824, 834, 836, 874* ; Tertiary, 880, 885, 888, 894 Miacis, 918 Miamia Bronsoni, 679*, 691 Miarolyte, 83 Miascyte, 85 Mica, 65, 81 dioryte, 86 schist, 83 syenyte, 83 ; trachyte, 84 Michelinia, 562, 597, 640 ; stylopora, 601 Michigan, mean height of, S3 ; salt group, 638 , Archaean in, 442, 445, 446, 449*, 450, 454 ; Cambrian in, 464, 465*, 468 Michigan Bay, 628, 633 Michigan, Lake, 200, 201*, 202, 540, 635 ; fiords of, 947, 948 ; glacier of, 968 Michipicoten Island, 445, 483 Micraster, 860; brevis, 866; cor- anguinum, 866; cor-bovis, 866; glyphus, 866 ; tercensis, 866 Microbes. See Bacteria Microblattina, 691 Microchaerus erinaceus, 926 Microclaenodon, 917 Microcline, 64, 83, 85, 129, 821 granite, 83 Micrococcus nitrificans, 137 Microcoelus, 867 Microconodon tenuirostris, 754* Microdiscus, 473, 481; speciosus, 473* Microdon, 621 ; bellistriatus, 598*, 602 Micro-granitic rocks, 77 Microlestes, 774, 789; antiquus, 773* ; Moorei, 773 Microlites, 77, 266, 273, 288*, 449 Microscopic texture, 76 Microspongia, 515 Microsyops, 918 Midford sands, 775 Midway epoch, 884, 885, 888, 896*, 915 Migrations forced by glacial condi- tions, 945 ; Arctic, between Amer- ica and Europe or Asia, 946, 950 Mill Creek beds (group), 840, 872 Millepeds, 419, 723 Millepores, 72, 130, 142, 431 Millerite, 637 Millstone grit, SO, 410 Millstones, 82 Milo Island, volcanoes, 296 Minas Basin, N.S., 350, 741 Mineral charcoal, 662 oil and gas, 62, 74, 80, 124, 138; from the Trenton limestone, 522- 523 ; from Salina group, 554 ; from the Devonian, 606 ; map of areas in Pennsylvania, 730* springs, 119, 128, 320; analyses, 121 Minerals, 63; making of, 317, 318, 323 Mines, temperature in, 257, 258 Minette, 83 Mingan Islands, 492, 493, 497, 500, 501,503 Minnesota, height of, 23 ; rain- fall, 944 ; Archaean in, 446. 448* ; Cambrian, 468, 469, 478, 484 ; Cal- ciferous, 491, 493; Trenton, 494; Niagara, 540 ; Subcarboniferous, 634 ; Glacial, 945, 968 Minnesota River, 947 Minyros Island, 296 (volcanoes) Miocene lake basins, 882, 933 period, 880, 881*, 883; lacus- trine, 893-895 Miohippus, 911, 912, 913*, 918, 919 ; annectens, 894 Miohippus beds, 886, 894 Miolophus, 925 Mispec conglomerate and slate, 594 Mississaga Eiver, 445 Mississippi, mean height of the state, 23; Cambrian in, 466; Subcarboniferous, 638, 648; Car- bonic, 635; Cretaceous, 638, 819, 823, 845, 854, 888 ; Tertiary, 884 ; Glacial, 945 Eiver, 24, 29, 30, 31; pitch and amount of discharge, 173, 190; delta of, 197; headwaters in the Glacial period, 947, 948, 964; Southwest Pass of, 198 Mississippian period, 632 Missouri, mean height of, 23 ; iron mountains, 444, 449 ; lead mines, 134, 342, 522 Eiver, 29 ; discharge and pitch, 173 ; headwaters in the Saskatch- ewan during the Glacial period, 964 , region of Upper, 829, 841, 844, 855, 893 Mitchell, Mt., 27 Mites, 420 Mitoclema cinctosum, 503 Mitra, 916, 922; cellulifera, 916; conquisita, 916 ; scabra, 926 Mixodectes, 917 Moa, 1014 Modiola, 525, 757, 916, 917 ; Bran- neri, 836 ; minima, 774 ; plicatula, 994 ; Shawneensis, 690 ; Wyom- ingensis, 690 Modioloides priscus, 472* Modiolopsis, 481, 516, 520; com- planata, 567; dubia, 558; faba, 514 ; modiolaris, 511* ; orthonota, 544*, 549 ; primigenia, 544*, 549 ; subalata, 551 ; superba, 514 Modiomorpha, 602, 621 Modulus compactus, 917 Mohawk Eiver, analysis of water of, 121 Moisture in rocks, 122, 205, 278, 311-312, 315, 324, 325, 334, 354, 802 Mokkatam, 160* Molasse, 920, 921 ; Lignitic, 926 ; Lower, 926 ; Eed, 926 Molds, 436 Mole, 158, 927 Molgophis, 692 ; macrurus, 682, 692 Molluscoids, 140, 419, 423, 425, 526 Mollusks, 55, 59, 72, 423 Molokai, 292 Moluccas, 921 Molybdate, 340 Mona Series, 440 Monads, 419 Monazite, 85, 455 Mongolia, 32, 83, 34 Monkeys, 54, 55, 402, 924, 930 Mono Lake, 26, 132*, 138*, 276, 296, 334 Monoclines, 102*, 109, 110* Monoclonius, 847 Monodon, 690 Monomyaries, 525 Monongahela Eiver series, 651 Monopleura marcida, 836 ; pinguis- cula, 886 Monoprionidae, 498* Monopteria, 690 Monotis, 756, 759; Albert!, 774; curta, 758* ; decussata, 774 ; Halli, 685 ; salinaria, 757 ; septentrion- alis, 792 ; speluncaria, 685 5 sub- circularis, 757, 758 ; variabilis, 685 Monotis bed, 757 Monotremes, 53, 54, 415, 789, 852, 858*, 917 Monroe County, Pa., Prosser's sec- tion of, 594, 6U6 Monson, Mass., quarry, 373 Mont Blanc. See Blanc Montalban, 446 Montana, mean height of, 23 ; Cam- brian in, 476, 477 ; Subcarbonifer- ous, 639; Carboniferous, 658; Triassic, 746 ; Jurassic, 748 ; Cre- taceous, Lower, 818, 820 ; Upper,. 825, 826, 828 ; Tertiary, 894, 918 Montauk Point, 224 Monte Eosa. See Eosa Montebello sandstone, 594 Monterey beds, 888 Monticulipora, 505, 511, 516, 524 y 545*, 561 ; adhaerens, 503 ; favu- losa, 520 ; fibrosa, 503 ; frondosa, 520 ; lycoperdon, 524 ; patula, 503 Montlivaltia, 760, 777, 778 (number of British); Atlantica, 854; cary- ophyllata, 777* Montmartre Gypsum beds (gypsi- ferous marls), 923, 924, 926 Montmorenci, fault at, 527* Montrose shales, 606 Monument Park, 185, 186* Monzonyte, 85 Moon, ^urface of, 11 ; density of, 16 Moosehead Lake, 577 Moravia, Cretaceous in, 838 ; Per- mian, 698 Morea cancellaria, 854 ; naticella, 854 Moreau Eiver, 856 Mormolucoides articulatus, 750* Morocco, 33, 920 Morosaurus, 763, 786, 836; Beck- lesii, 863 ; grandis, 763* Morris (Mt.), 605 Mortar, 79 Mortonia Eogersi, 898* Mortoniceras, 855 ; Delawarense, 854 ; Leonense, 837 ; Shoshonense, 855 ; Texanum, 855 1068 INDEX. Morven, 867 Mosasaurids, Cretaceous, 870 ; Cre- taceous (Lower), 864 (first) ; Cre- taceous (Upper), 826, 845, 847, 848 (number in Kansas), 848*, 849* Mosasaurs, Cretaceous, 816, 826, 867, 870 Mosasaurus, 848 ; Camperi, 864*, 866; Dekayi, 848; major, 848; princeps, 848, 849* Moschus, 927 Moscow shale, 598 Moss-animals, 427 .Mosses, 53, 153, 154, 434, 436, 677 ; ash, 74, 75 Mother liquor, 120 Moths, 419 Mount Desert, 218, 219*, 444 Mountain, 24 ; chain, 24, 389, 390 Mountain chains, composite charac- ter of, 28* ; mostly on the borders of continents, 392 limestone, 631, 632, 634, 695 mass, 26, 27 range, 24, 389, 390 ; relations of, to denudation, 387-388 slopes, 26, 27 ; angle of, 27, 28 system, 24, 889, 390 .Mountain-making, 345 , Archaean, 451-452 ; at close of Eopaleozoic, 526; post-Paleozoic, 853, 729 ; post-Triassic, 357, 798 ; post-Jurassic, 809 ; post-Meso- zoic, 359, 874 ; Tertiary, 367, 369, 982, 940 Mountains of circumdenudation, 345 ; of igneous accumulation, 845 ; of subterranean igneous accumulation, 345 Mouse, 53, 797 Muck, 154 Mud, 76. See also Earth (soil) Mud-cracks, 94*, 95, 140, 223, 260, 327, 334, 464, 554, 608, 605, 742, 745 lumps, 1978, 198 volcanoes, 305 Muir Glacier, 238, 244, 251 Inlet, 238 Mull, 867, 938 Mullet family, 848 Multiplicate species and structure, 421, 438, 439; in Cambrian 486*; in Paleozoic, 720, 723, 725; in Jura-Trias, 795-796 \ in Creta- ceous, 870 ; in Tertiary, 912 Multituberculates, 917 Murchisonia angulata, 567 ; Anna, 500; articulata, 567; bellicincta, 500, 507*, 514, 520 ; bivittata, 551 ; corallii, 567; extenuata, 558; gracilis, 514, 520 ; macrospira. 651; major, 515; Milleri, 507*, 514, 516; minima, 690; minuta, 558; tricarinata, 514; turbinata, 601 Murchisonian, 535 (Upper Silurian synonymy) Murchisonite, 321 Murex Alabamiensis, 915 ; simplex, 916 Muriatic acid, 68 Muschelkalk, 411, 769, 770, 771 Muscovite, 65, 83, 318, 321 ; gneiss, 83 ; granite, 82 Muscovite-and-biotite granites, 82 Muscovite-biotite gneiss, 83 Muscovy glass, 65 Musophyllum complicatum, 839 Mussel, 423 Mustakh Range, 240 Mustela, 927 Mya, 425 ; arenaria, 917, 983, 984 ; truncata, 917, 983, 984, 995 Myacites, 757, 760 ; Liassinus, 791 ; subcompressa, 760 Myalina angulata, 647 ; concentrica, 647; Halli, 685; perattenuata, 685*, 690; Permiana, 685; recta, 685; recurvirostris, 690; squa- mosa, 707 Mylacris, 691 Myliobatis, 643 ; Edwardsi, 926 Mylodon, 1000, 1001 ; Harlani, 1000, 1001 Myocaris lutsaria, 521 Myophoria, 756, 759; alta, 757; costata, 773; Goldfussi, 774; lineata, 760, 770, 771* ; orbicularis, 773 ; vulgaris, 773, 774 Myriapods, 418, 419 ; derivation of, 723-724; Upper Silurian, 574; Devonian, 575, 625, 721 ; Paleo- zoic, 721; Carboniferous, 657, 674 ; Tertiary, 922 Myrica, 831 Myrmecobius, 755 ; fasciatus, 755* Myrsine, 837 ; borealis, 838* Myrtacese, 922 Myrtle, 859, 921 Mysops, 918 Mystriosaurs, 787 Mystriosaurus Tiedemanni, 786* Mytilarca, 562, 621 Mytiloconcha incurva, 917 Mytilus, 129, 525, 916; Carteroni, 867; edulis, 984; Shawneensis, 690 ; simplex, 867 Naedoceras, 591 Naiadites carbonarius, 690 Naked Mollusks, 424 Namur dolomite, 696 Nanafalia beds, 888 Nanaimo beds, 831 Nanawale, 285 Nanomeryx, 918 Nanosaurus agilis, 765* ; Rex, 765 Nantucket, 43, 210, 944 (Glacial), 9&3, 1022 Naphtha. See Petroleum Naples, earthquake of 1857, 875 Naples group, 603, 605, 614, 620 Napoleon group, 638 Narragansett Bay, 444, 586, 638, 949 Nashville group, 489, 494 Nasopus caudatus, 684* Nassa, 916; Dalli, 916; scalata, 916 Natica, 707, 780, 916, 922 ; abyssina, 854 ; clausa, 983, 984, 995 ; Missis- sippiensis, 916; pedernalis, 836; permunda, 916 ; recurva. 916 Naticella costata, 7t3 Naticina, 916 Naticopsis, 690 - Natrolite, 68 Nauplius, 420, 721 Nautiloids, 676*, 690, 727 ; culmina- tion in Carboniferous, 675 Nautilus, 59, 424, 425*, 501, 614, 685, 700, 707, 727, 774, 843, 861, 869, 922 ; bidorsatus, 773 ; bucci- num, 602; centralis, 925; Dani- cus, 866 ; Dekayi, 842*, 854, 855 ; divisus, 691 ; eccentricus, 685 ; elegans, 837, 855; ferox, 501; Forbesanus, 690; imperialis, 925 ; Jurensis, 790; Konincki, 700*; Liardensis, 758; Nordenskioldi, 792 ; Permianus, 685 ; pomponius, 501 ; semistriatus, 791 ; Sibyllae, 758 ; spectabilis, 642 Navarro beds, 824 Navesink group, 821 Navicula, 894*; amphioxys, 163, 164* ; bacillum, 163, 164* ; serians, 164*, 165; semen, 164*, 165 Navigators Islands. See Samoan Neaera, 916 Nebraska, 23 (height); Carbonifer- ous in, 674, 690, 691 ; Permian, 660; Cretaceous, 826; Tertiary, 882, 893, 919, 933, 935 (elevation) Nebraska lacustrine beds, 919, 933 Necrogammarus Salweyi, 565 Necroleinur, 926 Negaunee, 446 Neithea grandicostata, 837; Mor- toni, 867; quinquecostata, 854, 855 Nelumbium tenuifolium, 839 Nelson Eiver, 947 Nematophyton, 564. 582, 590; Lo- gani, 582* Nemodon Vancouverensis, 837 Neobolus beds, 483 Neocene, 880, 883 - Neocomian epoch, 815, 831, 857 Neodevonian, 576 Neogene, 880 Neolithic period, 1013 Neomylacris, 691 Neopaleozoic time, 460, 535 NeoplagianJax, 917, 925 Neozoic, 880 Nepheline-basalt, 88 ; doleryte, 87 Nephelinyte, 87 Nephelite, 65 ; rocks, 81, 84, 85 ; ar- tificial formation of, 274 ; changes of, 320; in Archaean rocks, 449, 458 Nephriticeras, 602 ; maximum, 599 Nephroma arcticum, 946 Neptunea constricta, 915 ; entero- gramma, 916 ; Matthewsensis, 915 Nerinea, 781, 820, 834, 861; acus, 836; Austinensis, 836; bisulcata, 861*, 866, 867; cultrispira, 836; Defrancii, 790 ; depressa, 791 ; dispar, 837; Favrei, 865; gigan- tea, 865 ; Goodhallii, 780* ; Meri- INDEX. 1069 ani, 865 ; subula, 836 ; Texana, 835* ; trinodosa, 791 Nerinean beds, 791 Neriopteris, 689 Nerita, 916 ; deformis, 837 Neritina, 854 ; concava, 926 Nesodon, 927 Nesquehoning, Pa., 649, 650 Netherland coast, 378 Netherlands, Triassic in, 768 Neuropteris, 565, 639, 671, 685, 699, 704 ; angustifolia, 689 ; auriculata, 692, 704 ; biformis, 645 ; capitata, 645, 689 ; cordata, 689, 692, 704 ; Dawsoni, 622 ; fimbriata, 689 ; flexuosa, 692. 704 ; German, 689 ; hirsuta, 671*, 689, 692, 693; in- flata, 689 ; Loschii, 671*, 689, 704, 705* ; polymorpha, 595*, 622 ; tenuifolia, 671*, 689 Neuropteroids, Paleozoic, 721 ; Car- boniferous, 677, 679*, 691, 702 Neuropters, 141, 419, 600, 750, 771, 794, 900 (number of Florissant) Nevada, mean height of, 23 ; sili- ceous deposits in, 152 ; minerals made at Steamboat Springs in, 323, 334; mines, 338, 339, 340, 341* , Archaean in, 447 ; Cambrian, 464, 469, 470, 473, 474, 477, 478, 484; Lower Silurian, 495, 516; Niag- ara, 541 ; Devonian, 581, 589-590, 592, 606 ; Carboniferous, 658, 659, 674 ; Triassic, 747, 757, 758 ; Ju- ! rassic, 749, 759, 760; Tertiary, I 882, 886, 893, 895, 937 (eruptions) ; | post- Paleozoic upturnings, 733 Nevadyte, 84 Neve, 283 Neverita, 916 New Brunswick, upturnings in, 527, 533, 630, 732 , Archaean in, 444 ; Cambrian, 446, 466, 467, 474, 475, 476, 521 ; Lower Silurian, 493 ; Upper Silu- rian in, 541, 558; Devonian, 578, 593, 621 ; insects of, 600 ; fishes of, 587, 617 ; plants of St. John, 594 ; Subcarboniferous, 639; plants, 645 ; albertite of, 661 ; Carboniferous, 658, 692 New Caledonia, 23, 36*, 38, 145, 148, 787, 937 New England, marbles of, 524; Chazy in, 491 ; Corniferous, 580 ; Glacial, 949 ; Niagara, 541 ; Paleo- zoic, 714; Taconic, 490, 491, 495, 527 ; Triassic, 740 ; Upper Silu- rian, 538, 571, 572 New Guinea, 19, 22, 38 ; volcanoes of, 296 New Hampshire, 23 (height), 87, 817, 332 ; Archaean in, 446 ; Cam- brian, 466 ; Upper Silurian, 531 ; Niagara, 541, 544, 551; Lower Helderberg, 544 New Haven, Conn., trap dikes of, 299, 800*, 804* ; kettle holes, 993 ; depth of harbor, 226* New Hebrides, 35*, 36, 38, 296 (vol- canoes) New Ireland, 36, 38, 39 New Jersey, mean height of, 23 ; coast of, 162, 224 ; Highlands of, 530 ; marl-beds, 822 ; clay -beds, 822 ; subsidence, 350, 378 New Jersey Gavial, 848 New Mexico. 23 (height), 29, 340 (mines), 363, 364, 747 ; Archaean in, 444, 449 ; Lower Silurian, 495 ; Carboniferous, 674, 690 ; Permian, 660, 688; Triassic, 746, 755, 756, 758 ; Jurassic, 747 ; Cretaceou s, 813*, 817, 826, 828, 829 ; Tertiary, 882, 885, 893, 902 ; igneous erup- tions during, 937 ; Glacial, 945 New Eed sandstone, 400, 623, 697, 740 New Eiver, 200 New York, mean height of state, 23 ; iron ore beds, 127, 826, 449*, 450 ; lead mines, 542 ; marbles, 524 ; sulphur springs, 554 New York Bay, 211*, 224, 225, 230, 444,592 New Zealand, 22, 36, 37, 221 ; vol- canoes of, 296; connection with Australia, 737, 798, 1019 ; geysers of, 82, 305 ; glaciers of, 242 ; Upper Silurian in, 564 ; Triassic, 698, 737, 770; Jurassic, 776; Cretaceous, 857 (coal); Tertiary, 923, 937; Quaternary, 1019 chain of islands, 37, 39, 374 Newark group, 740 Newberria Condoni, 579 Newburg, 357 Newcastle coal, 401 Newfoundland, 17, 41, 48, 232, 252, 389, 424, 461, 536, 537, 552, 634 (coal-beds), 737, 793, 944, 948 (fiords); Archaean in, 443, 444, 446, 447; Paleozoic, 461; Cam- brian, 464, 465, 466, 467, 473, 475, 476, 496; Calciferous, 492, 496, 500, 501 ; Chazy, 503 ; Upper Sil- urian, 536, 571; Carbonic, 633, 635 ; Glacial, 944, 948 Banks, 882 Niagara period, 538 Niagara Eiver and Falls, 539, 540* (section), 542, 553, 580 ; obstructed by drift, 972* ; age of, 1023 Nicaragua, Carboniferous in, 659 Nickel, 70, 342 Nicola Lake, 746 Niger Eiver, 30 Niihau. 37 Nile, 30, 172, 173 (slope), 177 (floods), 190 (silt), 417 Nileus, 503 ; affinis, 573 ; armadillo, 573 ; rnacrops, 573 ; scrutatus, 573 Nimravus, 918 Ninafou eruption, 374 Nineveh coal-bed, 651 Niobium, 449 Niobrara group, 815, 825 Eiver, 886 Nipa, 921 Niso, 916 Nitrates, 63, 137, 138, 191 Nitric acid, 63, 124 Nitrification, 137 Nitrogen, 61, 118, 186, 153; from volcanoes, 293 Nitrous acid, 124, 137 Nitschea curvula, 699 Nobby Island, N. S. W., trap dike of, 313 Nodosaria Texana, 837 ; vulgaris 432* Nodules, 73 (phosphatic), 97 Norfolk and Suffolk cliffs, 219 Norian, 446 None (Upper), 757 Normandy, 518 Normanskill Graptolites, 516 ; shales, 515 North Cape, 521 North Carolina, 85, 231, 358, 946; mean height of, 23 ; coast, 224* ; iron ores, 449 Norway, 19, 33, 41, 85, 87 ; snow- line in, 234; Archjean in, 453; Cambrian, 482, 518 ; Lower Silu- rian, 518; Upper Silurian, 568, 568, 569 Norwich Crag, 927 Noryte, 86, 87, 532 Nostoc calidarium, 60 Notharctus, 918 Nothodon, 688 Nothosaurus, 773 Notidanus primigenius, 416*, 901* Notochord, 414 Notornis, 1014 Nototherium Mitchelli, 1006 Nova Scotia, 41 ; subsidence, 350 ; coal-beds, 634, 639 ; uplifts, 527, 538, 630 , Archaean in, 444; Cambrian, 466; Lower Silurian (close of), 527, 533; Upper Silurian, 537, 541, 558, 563, 573 ; Devonian, 578, 593 ; Subcarboniferous, 639 ; Car- boniferous, 653, 654*; Permian, 658, 660, 708 ; Triassic, 740 ; post- Paleozoic upturnings in, 732 Nova Zembla, 48, 776 Novaculite, 80 Nucleocrinus, 597 ; Verneuili, 585*,. 590 Nucleospira concinna, 592; pisi- formis, 551 ; pisum, 567 Nucula, 525, 602, 621, 757, 780, 792 ; lirata, 601 ; nasuta, 647 ; per- crassa, 854; Shaleri, 917; Shu- mardana, 647 ; tenuis, 984 Nuculana bellistriata, 690 Nuculites, 621 Nudibranchs, 424 Nullipores, 72, 140, 147, 156, 437 Nummulites, 433, 896; Eocene, 347,>20, 922* Nummulites levigatus, 926; num- mularius, 432*, -922*; radiatus, 926 ; variolarius, 926 Nummulitic epoch, 880 ; upturn- ing at close of, 932, 936 Numuku, 150 Nunataks, 240. 241*, 249* ; plants, of, 945 Nunda group, 605 Nyctilestes, 918 Nyssa, 896, 921 ; lanceolata, 889 1070 INDEX. Oahu, 150, 163, 179, 271*, 282 ; map of, 292 Obi-Irtish Kiver, 30 Obolella, 425, 481, 486, 496 ; crassa, 471* ; plicata, 520 ; polita, 478* Obolus, 72, 73 (composition of shell), 425, 482, 521 ; Apollinis, 427* ; Davidsoni, 567 ; Labradori- cus, 480 Obsidian, 64, 84 Cliff, 264*, 276,337* Occident, 21, 22 Ocean, abyssal depths of, 229 ; amount of salts in, 120, 121 ; sili- cates made at the bottom, 186; the great mineral spring, 120, 320 as a mechanical agent, 209 ; earth- quake waves, 213 ; abyssal work, 229 Oceanic currents, 42, 43, 46* era, 440 ; islands, 20, 22, 23 ; life not easily exterminated, 142 Oceans, arrangement of, 17 ; depth, 18, 19, 380 Ocoee group, 468 Octopods, 424 Oculina arbuscula, analysis of, 72 Ocydromus Australis, 1019 Odontaspis, 863 Odontidium, 163, 164*, 165 ; pinnu- latum, 894* Odontocephalus, 591 Odontocetus, 927 Odontopolys compsorhytis, 916 Odontopteris, 637, 671. 685, 693, 699 ; obtusiloba, 704 ; Schlotheimi, 670*, 689 ; sphenopteroides, 689 Odontopteryx, 923 (Eningen, fossils at, 921, 922, 926 Oesel zones, 568 Ogden, Utah, 860*, 861 ; Canon, 581 ; quartzyte, 580, 581 Ogygia, 482, 520, 521 ; Buchii, 520 Ohio, mean height of, 23 ; mineral oil and gas, 522, 523, 554, 607, 608, 609 Ohio River, filled by drift, 965 Ohio shales, 603, 606, 615 Ohiocrinus, 516 Oil. See Mineral oil Oil-creek group, 638 Oil-sand, 607 Okhotsk Sea, 927 Oklahoma, 836; mean height of, 23 O"land, 521 Olcostephanus Astierianus, 865 ; Speetonensis, 865 ; Traskii, 837 Oldhamia, 482 ; antiqua, 481* ; radiata, 481* Olean conglomerate, 647 Olefiant gas, 528 Oleic acid, 124 Olenellus, 467, 473*, 479, 481, 482 ; asaphoides, 473; Callavei, 481; Gilberti, 478, 474* ; Kjerulfi, 482 ; Thompson!, 478* ; Vennontanus, 473* Olenellus zone, 464, 482 Olenoides, 482 ; Fordi, 473* Qlenopsis, 482 Olenus, 481, 482, 483; micrurus, 481* Olenus schists, 482 Oligobunis, 918 Oligocarpia, 699, 756; Gutbieri, 699 ; robustior, 749* Oligocene, 880, 886, 918, 920, 921, 926 Oligoclase, 64* ; gneiss and granite, 83 Oligoporus nobilis, 641*, 646 Oliva, 922 ; Mississippiensis, 916 Olivella, 916 Olivine. See Chrysolite Omnivores, 930 Omosaurus armatus, 787 Omphacyte, 88 Omphyma, 567 ; turbinata, 564*, 567 Onchidium, 424 Onchus, 546, 565, 626 ; Clintoni, 546, 550 ; Deweyi, 550 ; tenuistriatus, 566* Oncoceras, 551, 561 ; gibbosum, 549 ; ovoides, 558, 562 Oneida conglomerate, 538 Oneonta sandstone, 603, 606, 612, 618, 621 Oniscia harpuia, 916 Oniscus, 509, 783 Onoclea sensibilis, 840, 922 Onondaga beds, sections of, 552, 553* Lake, 553 limestone, 576, 581 period, 408, 410, 535, 552-558, 570, 572 salt group, 552 Ontarian, 446 Ontario, salt group in, 552 Ontario (Lake), 200, 201*, 494, 533, 946, 947 (depth) Onychodus, 417 ; sigmoides, 589* Onyx, 133 Oolitic, 82 ; limestones, 79 Oolyte, 79, 96 ,Bath, 775, 777, 790; Corallian, 790; Great, 775, 777, 779, 790; Oxford, 775, 790 Oolytic epoch, 738, 775 Opal, 62, 64, 135 Operculates, 54 Ophiacodon grandis, 688 Ophiderpeton, 706; Brownriggii, 704 Ophileta, 495, 499*, 515, 520 ; com- pacta, 500, 520 ; complanata, 499* ; levata, 499* ; Owenana, 514 ; pri- mordialis, 478* ; uniangulata, 499* Ophiolyte, 79, 89 Ophiurans, 55 Ophiuroids, 429, 505*, 646 Ophyte, 86 Opossum, 415, 902, 910, 924, 926 Oppelia, 794 Oquirrh Mts., 340, 469 Oracanthus Milled, 702 Oracodon conulus, 853* Orang-outang, 54 Orange, N.J., columnar basalt, 262* - Bay, 858 sand group, 891, 965 Orbicula, 482 ^-'' Orbicular dioryte, 87, 97* Orbiculoidea, 514, 612; Lodensis, 612*, 620; minuta, 592, 602; ru- gata, 567; tenuilamellata, 562; Vanuxemi, 557 Orbitoides, 433, 896 ; Mantelli, 896, 898* Orbitoides limestone, 896 Orbitolites, 433 Orbitulina conoidea, 865 ; discoidea, 865, Orbitulites Texanus, 834*, 836 Orbulina universa, 432* Orca, 144 Orchestia, 420* Orchids, 435 Ordovician, 489 Ore, ores, 327, 845, 810 ; origin of, 342, 348 Oregon, 23, 25; glaciers of, 240; igneous action in, 265, 266, 280 ; volcanoes of, 296; Cretaceous in, 818, 830; Tertiary, 882, 885, 892; John Day beds of, 911; sandstone veins, 344 Oreodon, 907, 918 ; gracilis, 910* Oreodon beds, 886, 894, 910, 918 Oreodoxites plicatus, 889 Oreti series, 770 Organic acids, 665 contributions to rock-making. See Kocks, organic constituents of nature, essential elements of, 9, 413 remains, 71 Orient, 21, 22 Orinoco Kiver, 30, 456 Oriskany period, 577 sandstone, 577, 578 Orizaba (Mt.), height of, 937 Ormoceras, 501 ; crepriseptum, 516 ; tenuifilum, 514 Ormoxylon Erianum, 622 Ornithomimus, 847, 856 ; velox, 847* Ornithopoda, 761, 764, 786, 845, 863 Ornithorhynchus, 415, 795 Ornithostoma, 863 Orodus, 644, 692, 702 ; mammillaris, 644*, 647 Orogenic work, 345, 376, 391 movements, Tertiary, of Long Island and Martha's Vineyard, 1021*. See further, Mountain- making Orohippus, 905, 912, 913*, 918; agilis, 905* Oromeryx, 918 Orthacanthus, 687 ; arcuatus, 692 Orthaulax Gabbi, 899*, 917 ; pugnax, 916 Orthaulax bed, 89,1 Orthids, 719 (time range) ; Upper Silurian, 574 Orthis, 310, 425, 426, 481, 482, 516, 517, 521, 550, 561, 562, 568, 579, 622, 642, 705 (last in Permian), 707 ; acuminata, 503 ; arcuata, 625 ; biforata, 507*, 514, 520, 550 ; Bil- lings!, 475*; biloba, 548*, 551; borealis, 503; Bouchardi, 520; INDEX. 1071 -calligramma, 520, 522, 567; cos- talis, 502*; Davidsoni, 568; dis- cus, 563; disparilis, 503, 514; elegantula, 519*, 520, 551, 552, 562, 563, 567, 568, 569; flabellulum, 519*, 520; grandaeva, 499*, 500; granulosa, 625 ; Highlandensis, 471* ; hipparionyx, 579 ; hybrida, 551, 563; imperator, 503; im- pressa, 592, 620, 621 ; inaequalis, 602; interlineata, 626; lowensis, 602 ; lata, 567 ; lunata, 567 ; lynx, 521; McFarlani, 592; Michelini, 703 ; Michelini var. Burlingtonen- .sis, 642*, 646; musculosa, 579; oblata, 562, 563, 579 ; occidentals, 507*, 514; orbicularis, 567; pal- liata, 568; parallela, 626; parva, 521 ; Pecosi, 690 ; perelegans, 563, 579; planoconvexa, 562; platys, .503; plicata, 626; porcata, 520; Porcia, 503; prava, 602; puncto- .striata, 563; Salemensis, 471*; . striatula, 426*, 520, 625, 626, 628 ; subaequata, 503 ; subcarinata, 563 ; suborbicularis, 602 ; subquadrata, 514 ; testudinaria, 507*, 514, 521 ; Tioga, 621 ; tricenaria, 507*, 514 ; tubulostriata, 563 ; Tulliensis, 592 ; Vanuxemi, 591, 602 ; varica, 560*, 562 Orthis family. See Orthids Orthisina, 425, 481; festinata, 471*; orientalis, 471*; Shumar- dana, 685 Orthoceras, 78, 481, 488, 499, 508, 511, 515, 516, 517, 520, 521, 546, 549, 551, 561, 562, 567, 568, 586, 591, 599, 613, 614, 625, 626, 642, 675, 705, 707, 719, 727, 736, 756; Allumettense, 503; amplicamera- tum, 516 ; anellum, 514 ; annula- tum, 520, 551, 567, 568, 569 ; arcuo- liratum, 520; Barrandii, 520; bebryx, 620 ; Blakei, 757 ; bulla- tum, 567, 573 ; coralliferum, 516 ; crotalum, 602 ; desideratum, 546 ; diffidens, 503; explorator, 503; fulgidum, 620; furtivum, 503; ibex, 568, 573 ; interruptum, 627 ; junceum, 506, 508*, 514; laquea- tum, 500* ; Ludense, 567 ; Luthei, 501; Midas, 568; moniliforme, 524; multiseptum, 549; nobile, 642; olorus, 508*, 514; Ozar- kense, 500 ; pacator, 620, 621 ; primigenium, 499*, 500, 501, 517* ; rectiannulatum, 503 ; rectum, 551 ; strix, 551 ; subflexuosum, 627 ; subulatum, 602, 620 ; tenui- annulatum, 567 ; tenuiseptum, 503 ; transversum, 516 ; vagans, 520 ; velox, 503 ; virgatum, 569 Orthocerata, 310, 497, 522, 561, 578, 700 Orthoceratite limestone, 627 Orthoclase, 64* ; augite, 84 Orthodesma, 516; parallelum, 511* Ortholyte, 83 Orthonota, 602, 621 ; affinis, 567 ; angulifera, 567 ; curta, 551 ; un- dulata, 598*, 602 Orthophyric rocks, 77, 84 Orthopteroids, 721, 722; Carbonic, 722 (culmination) ; Carboniferous, 677, 679*, 691 ; Coal-measure, 701, 702* Orthopters, 419, 574, 600, 702, 771, 794; number of Florissant, 900 Orthothetes Chemungensis, 591, 592 ; crenistria, 700* ; subplanus, 563 ; umbraculus, 704 ; Wool- worthanus, 563 Orthrocene, 880 Orycteropus, 54 Oryctoblattina, 691 Osage group, 634, 637 Osars, 972 Oscillatoria, 60 Oshima (Mt.), 280 Osmeroides, 862 ; Lewesiensis, 862* Osmunda affinis, 839 ; spicant, 74 Osteolepis, 417, 621, 627 Ostracoids (Ostracodes), 421 ; Cam- brian, 474*, 481, 486, 487 Ostrea, 780, 828, 829, 840, 854, 864, 916 ; acuminata, 790 ; aquila, 865 ; belliplicata, 854 ; bellovacina, 925 ; biauriculata, 866 ; carinata, 837 ; compressirostra, 897*, 915; con- gesta, 841*, 854, 855 ; Couloni, 865 ; crassissima, 926 ; decussata, 866 ; deltoidea, 790 ; diluviana, 866 ; dis- parilis, 917 ; falcata, 854 ; Frank- lini, &36; Georgiana, 898*, 916; gigas, 927; glabra, 855; glandi- formis, 854 ; Johnsoni, 915 ; larva, 841*, 854, 855, 866 ; Liassica, 774, 790; macroptera, 865; Marshii, 780*; 790, 791 ; Matheroni, 866 ; Merceyi, 866 ; percrassa, 917 ; prae-compressirostra, 915; Pulas- kensis, 915; quadruplicata, 837; sellaeformis, 889, 897*; solitaria, 791 ; Sowerbyi, 790 ; stringilecula, 760; subspatulata, 854; subtri- gonalis, 856 ; thirsae, 915 ; titan, 892; trigonalis, 916; vesicularis, 866 ; Vicksburgensis, 916 Ostrea sellaeformis beds, 889 Ostrich, 54, 852, 871, 902 Otodus, 843, 863; appendiculatus, 843*, 854 ; obliquus, 926 Otozamites contiguus, 791 ; lingui- formis, 756* ; Macombii, 756 Otozoum, 753 ; Moodii, 752* Ottawa, 490, 491, 493, 494 Ottrelite, 315, 819 Ottrelitic rocks, 82, 83, 467 Ouachita Mts., 380, 389, 732, 817 Outcrop, 99* Ovibos bombifrons, 999 ; cavifrons, 999, 1002 ; maximus, 1002 ; mos- chatus, 1002 Ovis, 927 Owl, 902 Ox, 54, 907 Oxfordian group, 775 Oxidation, 122, 123; constructive effects, 127; destructive effects, 125 Oxyaena, 918 Oxyclaenus, 917 Oxygen, 61 , 122 ; in atmosphere of the Lithic era, 440 Oxyrhina, 144, 843, 863; hastalis, 917; Mantelli, 843* Oxyria, 240 ; digyna, 945 Oyster family, 840 Oysters, 56; analysis of shell, 72 Ozark series of Broadhead, 468 Pachysena, 918 Pachycardium Spillmani, 855 Pachyderms, 927 Pachydiscus Brazoensis, 836; per- amplus, 866 ; Whitneyi, 837 Pachynolophus, 918 Pachyrhizodus, 843 Pachytheca, 564 Paciculus, 918 Pacific border of America, 18, 24 ; volcanoes of, 295, 296, 297, 987; glaciers of, 945 ; submerged river channels, 949 ; Triassic and Jur- assic of, 746, 756, 808 ; Cretaceous, S18 ; Tertiary, 885 ; lacustrine de- posits of, 893 Pacific Ocean, 17, 19, 20, 31, 41, 42, 43; temperature of, 49; -salinity of, 121 , island-chains of, 35-39*, 40, 295, 296, 393, 395 , islands of, 17, 20, 23 (number), 38, 39, 151, 161, 182, 227 ; eleva- tions in, 350 , system of currents, 43, 44 , volcanoes in, 295, 296, 297, 938 Pah-Ute Lake, 895; Kange, 366, 812 Pahoehoe, 287, 288 Pahranagat Eange, 366*, 606 Painted Canon, 758 Palaeacis, 639; cuneiformis, 646; obtusus, 646 Palaeacodon, 918 Palaeanatina, 621 Palaearca, 481, 520 Palaeaspis Americana, 557* Palaeaster, 481, 516, 520 ; Dyeri, 511 ; Jamesi, 510*, 511 ; magnificua, 511 ; matutinus, 505*, 514 ; Nia- garensis, 429*, 551 Palaeasterina primaeva, 567 Palasechinus, 567 Palaeichthyes, 415 Palaeinachus, 782 Palselodi, 923 Palaemon, 703 Palseoblattina DonviUei, 566 Palaeocampa, 723 ; anthrax, 676, 691 Palseocaris typus, 678*, 691 Palseocastor Nebrascensis, 911 Palaeocreusia, 591 ; Devonica, 587 Palaeocrinus, 514; striatus, 502*, 508 Palaeoctonus Appalachians, 754 Palaeocyclus, 567 ; rotuloides, 545*, 550 Palaeocystites Chapmani, 508 ; Daw- soni, 503 ; pulcher, 503 ; tenuira- diatus, 503 Palaeogene, 880 Palseohatteria, 706, 707, 795, 797; longicaudata, 706* 1072 INDEX. Palaeolagus, 918, 919 Palaeolithic Man, 1011 Palaeomanon, 550 Palseomyrmex prodromus, 788 Palaeoneilo, 621 ; fllosa, 620 Palaeonictis, 918, 925 Palseoniscidae, 620 Palaeoniscoids, 417 Pateoniscus, 417, 603, 702, 705, 772 ; antipodeus, 699 ; Bainei, 770 ; Browni, 692 ; comptus, 707 ; Devonicus, 620 ; elegans, 707 ; Freieslebeni, 417*, 705*, 707, 740 ; gracilis, 692; Jacksoni, 692; Leidyanus, 692 ; lepidurus, 417* ; peltigerus, 692; sculp tus, 770; scutigerus, 692 Palaeopalaemon, 620 ; Newberryi, 615* Palaeophis toliapicus, 925 ; typhaeus, 923, 926 Palaeophonus nuncius, 565 Palaeopteris Rcemeriana, 704 Palaeornis, 864 Palaeosaccus Dawsoni, 497 Palaeosaurus, 773 ; Fraserianus, 754 Palaeoscincus, 856 Palaeospondylus Gunni, 1031 Palaeosyops, 907, 918 ; paludosus, 907* Palaeotherium, 926; crassum, 926; curtum, 924, 926 ; magnum, 924, 926 ; medium, 926 ; minimum, 926 ; minus, 926 Palseothrissum Freieslebeni, 740 Palapteryx, 54, 1014 Palawan, 40 Paleocene, 880 Paleothere, 924 Paleozoic, 407 time, 460 ; growth of American continent during, 714 ; biological changes in, 716; mountain-mak- ing following, 729, 733 Palinurus, 73 Palisade Range, 358, 808 System of ranges, 357, 880, 389 Triassic area, 740, 741, 743, 798, 799, 800 Paliurus zizyphoides, 839 Pallium, 425 Palmacites, 859 Palms, 53, 409* (time range), 434, 435, 879 Palo Duro beds, 884, 885, 919 Paloplotherium annectens, 926 Palpipes priscus, 783* Paludina, 152; fluviorum, 861*, 864 ; lenta, 926 ; orbicularis, 926 Paludina limestone, 864 Paluxy sands, 817 Pamlico Sound, 224* Pampas, 24 Pamunkey formation, 888 Panama, 891 (Miocene) ; conglom- erate, 680, 638 Panamints, 23 Panchet group, 698, 769, 778 Pandanus family, 777 Panenka, 621 Paniselian beds, 925 Panochthus, 1004 Panolax, 919 Panopsea Americana, 917 ; elongata, 915; porrectoides, 916; reflexa, 917 Panther Creek anthracite basin, section of, 649* Pantolambda, 917 Pantolestes, 918 ; brachystomus, 906 Paolia vetusta, 679* Papandayang (Mt.), 277 Papaver, 240 Parabatrachus Colei, 708 Paraclases, 113 Paracyclas, 592, 602, 621 ; elliptica, 590, 601 ; proavia, 585*, 590 Paradoxides, 474, 475, 477, 482 ; Bennetti, 475; Davidis, 481; Forchhammeri, 482 ; Harknessi, 481 ; Harlani, 475, 476* ; Eegina, 475, 476*, 521; Solvensis, 481; Tessini, 482 Paradoxides beds, 467, 481, 482; zone, 464 Paragonite, 84 ; schist, 84 Paraguay River, 183 Paramorphs, 62, 67, 69, 70 Paramys, 917, 918 Paria, 747. Parictis, 918 Paridigitates, 906 Paris, 17, 347, 926 basin, 774, 872, 880, 920, 928 Parisian group, 884, 925 Parma sandstone, 657 Parodiceras, 602 Paromylacris, 691 Parophite schist, 84 Parrots, 54, 923 Pasceolus, 515 Passalacodon, 918 Patagonia, 20, 209, 925 Patella, 130, 471, 487, 780 Patellina Texana, 834*, 836 Paterina, 480, 486 Patoot group (beds), 831, 840, 872 Patriofelis, 918 Patterson Glacier, 240 Patula alternata, 966; perspectiva, 966 ; solitaria, 966 ; striatella, 966 Patuxent River, 889 Paumotu Archipelago, 20, 86, 37, 145, 222, 350 Paurodon valens, 767* Peace Creek, Fla., deposits, 890, 892 (bone beds) River, Brit. Amer., 444, 659, 746, 830 ; coal of, 825 Pearl sinter, 82 ; spar, 540 Pearlyte, 84 Peat, 74, 81, 153*, 666 ; composition of, 661, 713 Pebbles in Archaean rocks, 448, 449 Pebidian period, 457 Peccary, 54 Pe-chi-li, 198 (gulf), 696 (province) Pecopteris, 671, 684, 699, 704, 750, 756 ; acuta, 689 ; arborescens, 654, 671*, 689, 692, 704; Browniana, 831; Candolleana, 692-693, 705; cyathea, 689; dentata, 693, 705; erosa, 689 ; Germari, 705 ; lati- folia, 705; Miltoni, 698, 704; notata, 689, 693; oreopteridea,. 693, 705; pennaeformis, 705; Pluckeneti, 693, 705 ; preciosa, 622; pteroides, 689, 693, 705; robustior, 749*; serrulata, 689; unita, 689 Pecten, 525, 756, 780, 860, 916; Alabamiensis, 915 ; anatipes, 916 ; asper, 865, 866; Burlingtonensis, 855; calvus, 791; ciuctus, 791, 865; circularis, 867; Clintonius, 917 ; decennarius, 917 ; deforrnis, 757 ; discites, 774 ; fibrosus, 790 ; Groenlandicus, 983, 984 ; irradians, 994; Islandicus, 983, 984, 995; Jeffersonius, 899*, 917 ; lens, 790 ; Madisonius, 917; Nillsoni, 855; nuperus, 916 ; operculiformis, 837 ; Poulsoni, 898*, 916; quadri- costatus, 865 ; quinquecostatus, 854 ; Stantoni, 836 ; vagans, 790 ; Valoniensis, 774, 790; venustus, 854 Pectinated rhombs, 430 Pectolite, 68 Pectunculus arctatus, 916; quin- querugatus, 917 ; subovatus, 917 Pegmatyte, 83 Pei Ho, 198 Pelagic and abyssal life, deposits from, 143-144, 229 Pelagite, 71 Pele's hair, 279 Pelew Islands, 350 Pelicans, 923 Pelion Lyelli, 682, 683*, 692 Pelorosaurus Becklesii, 863 Peltoceras, 794 ; athleta, 791 Peltodus, 692 Pelycodus, 918 Pemphix Sueurii, 771* Pen of the Cuttle-fish, 424* Penarth beds, 769 Peneplane, 204 Pennant, 696 Pennine chain, 695, 696 Pennsylvania, 23 (height), 24, 25, 41, 356, 357, 358, 882, 383, 388, 891, 399, 405 ; coal-field, map of, 649* ; copper ores, .745; iron ore beds, 127 ; marbles, 524 , mineral gas and oil in, 606, 607, 609, 664, 730*, 731 ; yield of, 608, 609 , diagram showing the courses and flexures of the ridges, 729, 731* , rocks, section of, 727, 728 ; Pros- ser's section of, 594, 606 , topographical map of, 357, 729 r 730*, 731, 798 Pennsylvania period, 632 Penobscot Bay, 544, 552 Penokee-Gogebic range, 446 Penokee-Marquette belt, 446, 449 r 454 Pentacodon, 917 Pentacrinus, 59, 428*, 719, 758, 778 ; asteriscus, 757, 758*, 760; Bria- reus, 778*, 790 ; caput-medusse, 428* ; decorus, 58* ; subangularis,, 79 INDEX. 1073 Pentamerella arata, 581, 590 Pentamerids, 574 Pentameroceras mirum, 551 Pentamerus, 425, 550, 552, 562, 568; borealis, 568; brevirostris, 569 ; caudatus, 567 ; comis, 601 ; conchidium, 552, 569 ; fornicatus, 563 ; galeatus, 560*, 562, 563, 567, 568, 569, 626, 628 ; globosus, 520 ; Knightii, 551, 564*, 565,' 567, 568, 569; Isevis, 569; oblongus, 520, 545, 546*, 550, 551, 552, 567, 568, 569 ; occidental, 551 ; pseudo- galeatus, 560*, 561, 562 ; uodatus, 520 ; Verneuili, 561* Pentamerus, Lower, 535; Upper, 535 Pentremites, 430, 585, 590 Pentremites, 597, 601, 602, 641; Godoni, 640*, 646; ovalis, 626; pyriformis, 640*, 646 Pentremital group, 637 Peoquop Range, 365 Peperino, 80 Peralestes, 789* Peramus, 789* Peraspalax, 789* Perch, 812, 879 ; family, 862, 901 Perchoerus, 918 Pericentric stratification, 99 Peridot, 67 Peridotyte. 89 Perihelion and aphelion, changes of, 254 Period, 406 Peripatus, 723 Periptychus, 917 Perisphinctes, 749, 760 ; Colfaxi, 760; Muhlbachi, 760; virgulati- formis, 760 Perlyte, 122 Permian period, 660, 689, 690; foreign, 697, 704 in India, etc., supposed to be glacial. 698 ; emergence of Ant- arctic land, 737 Permo-Carboniferous, 635, 687 Perna maxillata, 378 ; mytiloides, 790 Perry sandstone, 594, 606 Persia, plateau of, 26 ; Cretaceous in, 857 ; Tertiary in, 920 Persian Gulf, 41 Perthite, 321 Peru, 41, 51, 213, 222 ; volcanoes of, 296; Cretaceous in, 857, 867; Tertiary, 935 Peruvian islands, 153 Petalite, 449 Petalodonts, 643, 647, 705 Petalodus, 680, 692; curtus, 648; destructor, 680*, 692 Petraia, 515, 520, 567 ; bina, 520, 567 ; profunda, 517 Petricola, 157 ; centenaria, 917 Petrifactions, 131, 135, 143 Petrified forests, 135 Petrodus, 692 ; occidentalis,680*,692 Petroleum, 522, 555, 661 Petrosilex, 84 Petschora-land, 776 Phacoceras, 675 ; Dumbli, 675, 676*, 691 Phacops, 422, 520, 521, 551, 561, 568, 570, 579, 586, 591, 599, 626; bufo, 599*; callicephala, 515; caudata, 567, 568 ; Downingii, 565*, 567, 573 ; elegans, 568 ; fecunda, 568, 570 ; granulata, 625 ; latifrons, 625, 626, 627; Logani, 561* ; longicaudata, 567 ; nupera, 614 ; rana, 592, 599*, 614 ; Stokesi, 567 ; trisulcata, 550 Phaenogams, 434-435, 595; Neo- paleozoic, 460 Phaethonides, 591, 643 ; occidental, 614 ; spinosus, 614 Phalangidse, 691 Phaneropleuron, 418, 621, 625; curtum, 617*, 619, 621 Pharella Dakotensis, 855 Phascolestes, 789 Phascolotherium, 789* ; Bucklandi, 789* Phasma, 677 Phenacodus, 903, 910, 917, 918, 925 ; primaevus, 903* Phenocryst, 77 Philippine Islands, 296 (volcanoes), 297, 920, 921 Phillipsasjrea, 718; gigas, 590; Verneuili, 584*, 585, 590 Phfflipsid, 521, 643, 676, 686, 700; Cliftonensis, 691 ; major, 691 ; Missourieusis, 691 ; scitula, 691 ; seminifera, 700* Phillipsite, 136, 144 Phlegethontia, 692 ; linearis, 682 Phlegraean Fields, volcanic region Phlogopite, 65 Phlyctaenaspis Acadica, 616*, 618 Phoberus caecus, 59 Phrenicites, 921 Phrenix Islands, 20 Pholadella, 621 Pholadomya, 759, 780 ; abrupta, 917 ; cuneata, 925 ; fiducula, 790 ; Lincenumi, 855 ; Marylandica, 915; multicostata, 791; ovulum, 791 ; papyracea, 855 Pholas, 157, 158; alatoidea, 915; Phonolyte, 85; columnar, 263*, 264* ; solubility, 122 Phos Texanus, 916 Phosgenite, 335 Phosphates, 63, 69 Phosphatic concretions, 78, 493, 891; deposits, 153; fossils, 314, 487 rock-material, 72-74, 141 Phosphoric acid, 69, 72, 73, 74, 75, 153, 241, 663 Phosphorite beds of Quercy, 926 Phosphorus, 62, 63, 123; in mineral coal, 663 Phragmites Alaskanus, 839 Phragmoceras, 567 ; parvum, 551 Phragmodictya, 646 Phrynus, 724 Phthanocoris, 722 ; occidentalis, 691 Phthanyte, 82 Phylloceras, 793, 794; ptychoicum, 791 Phyllograptns, 470, 520 ; Anna, 500 ; typus, 498* Phyllopods, 421, 439; Cambrian, Lower, 474* ; Cambrian, Middle, 476, 477* ; Chemung, 614, 615* ; Corniferous, 586 ; Hamilton, 599, 600* ; Lower Silurian, 521 ; Paleo- zoic, 720 ; Subcarboniferous, 643 Phyllyte, 80, 89 Physa, 152 ; heterostropha, 682 Physeter, 912, 927 Physiographic chart of the world, 46, 47*, 350 Physiographic geology, 14, 15 Physospongia, 639, 646 Phytolitharia, 163, 164* Phytopsis cellulosa, 505 Pichincha (Mt.), 26, 296 Pickwell Down beds, 625 Picotite, 88 Picryte, S"8 Pictured rocks, 94*, 464, 465* Piedmont region, 24, 448 Pigeons, 54 Pikermi beds, 927 Pike's Peak, 811, 876 Pile worm, 158 . Piloceras, 520, 573 ; Canadense, 501 ; Wortheni, 501 Pilton beds, 625 Pilularia globulifera, 436* Pinacoceras Metternichi, 774; par- ma, 774 Pine, 435, 436, 667, 668, 777, 859 Pine Mountain, Ky., 543, 657 River, 746 Finite, 68, 318, 320 Pinites, 704, 777 Pinna, 129, 760 ; affinis, 925 ; decus- sata, 866; expansa, 759*; Mis- souriensis, 647; Mulleti, 865; peracuta, 690 Pinnularia aequalis, 164*, 165 ; bore- alis, 164*, 165; peregrina, 437*, 894*; viridis, 164*, 165; viridula, 164*, 165 Pinon Range, 365, 733 Pinus, 859, 922; abies, 74; suc- cinifer, 922 Pinyte, 84 Pipestone quartzyte, 468 Pisolite, 96* Pisolitic limestone, 859 Pit River, 747, 749, 809 Pitchstone, 84 Pithecanthropus erectus, 1036 Pitt, Mt., 296 Pittsburg coal-bed, 653 Placenticeras Guadalupae, 855 ; pla- centa, 841, 842*, 854, 855 Placoderms, 417 ; Trenton, 509 Placodus, 773 Placoparia, 520, 521 Placuna scabra, 854 Placunopsis, 690 Planer (Lower), 866; (Middle), 866 Plagiaulax, 768, 789, 864; minor, 789* ' Plagioclase, 64 Plaisancian beds, 927 Planation, 167, 169, 219, 221* Plane tree, 831, 922 DANA'S MANUAL 68 1074 INDEX. Planorbis, 152, 856; discus, 926; euomphalus, 926 Plant-beds, 933 Plantain, 812 Plants, 71, 72 ; geographical distri- bution of, 52-60 ; phosphoric acid in ash, 73 ; analyses of, 74, 75 ; chemical work by, 136 ; pro- tective eifects of, 155; materials for rock-making, 140, 143 Plaster of Paris, 69 Plastic clays, 821, 825, 925 Plasticity of rocks from superheated Plastomenus, 850 Platanus, 831, 840, 922 ; aceroides, 839 ; Guillelmse, 839 ; Reynoldsii, 839 Plateau, 25, 188 belt, 739, 748, 749, 811 ; region, 818 Plateaus carved into mountains, 188 Platephemera antiqua, 600* Platinum, 331, 376, 455 Platte River, 29, 885 Plattendolomit, 697 Platyceras, 478, 487, 499, 561, 562, 568, 570, 574, 578, 585, 590, 598, 602, 612, 642; angulatum, 548*, 551 ; auriformis, 503 ; carinatum, 592, 602 ; conicum, 592, 602 ; den- talium, 592 ; dumosum, 586*, 590 ; equilaterale, 647 ; erectum, 602 ; Haliotis, 573 ; nodosum, 592 ; pri- maevum, 471, 472* ; rectum, 602 ; reversum, 647 ; spirale, 579 ; sym- metricum, 602; thetis, 602; ven- tricosum, 562 ; vetustuin, 625 Platycrinus, 597, 646; Saffordi, 640*, 646 Platygnathus, 626 Platygonus, 919 Platyschisma helicites, 567 ; heli- coides, 578 Platysomus, 705; gibbosus, 707; macrurus, 707 Platystoraa, 562, 590, 612, 621 ; Ni- agarenese, 548*, 551 Platystrophia biforata, 507*, 550 Playa, 196 Pleasant (Mt.) beds, 606 Plectambonites, 503, 550 ; sericeus, 507*, 514, 520, 522, 524, 550; transversalis, 426*, 548*, 551, 568 Plectoceras, 501 Plectrodus mirabilis, 567 ; pleio- pristis, 567 Pleistocene life, North American, 997 ; South American, 1002 ; Eu- ropean, 1004; Australian, 1006; foreign, 1004 ; man, 1008 Pleistocene period, 890, 940, 941 Plesiadapis, 925 Plesiosaurus, 773, 785, 790, 856, 863 ; dolichodeirus, 784* ; macrocepha- lus, 785* ; oeciduus, 828, J356 Pleuracanthus Gaudryi, 702, 703* Pleuroceras spinatum, 781* Pleuroccelus altus, 836 ; nanus, 836* Pleurocystites filitextus, 505*, 514 ; tenuiradiatuB, 517 Pleurodictyon, 626 Pleurolichus, 918 Pleuromya, 760 ; laevigata, 837 ; uni- oides, 760 Pleurophorus elongatus, 774; sub- cuneatus, 685* Pleurorhynchus, 520 Pleurosigma angulatum, 437* Pleurotoma, 922; abundans, 916; Americana, 916; attenuate, 926; beadata, 916 ; congesta, 916 ; cris- tata, 916 ; declivis, 916 ; Heilprini, 916; Huppertzi, 916; moniliata, 915; perexilis, 916; rotaedens, 916 ; tenella, 916 ; Texana, 855 ; Tippana, 855 Pleurotomaria, 59,487, 493,499, 516, 520, 521, 525, 551, 562, 586, 590, 598, 621, 642, 700, 707, 780 (culmi- nation), 792 ; Adansoniana, 59 ; an- tiquata, 503 ; Attleborensis, 471 ; Austinensis, 837 ; biangulata, 503 ; Brittoni, 854; calcifera, 500; ca- lyx, 503 ; carbonaria, 690 ; docens, 503 ; Grayvillensis, 690 ; grega- ria, 500; litorea, 544*, 549; Ohio- ensis, 516 ; pervetusta, 549 ; Shu- mardi, 647 ; solarioides, 549, 551 ; sphaerulata, 675*, 690; staminea, 517 ; subconica, 514 ; tabulata, 675*, 690; turbinea, 627; virgu- lata, 602 Pliauchenia, 912, 919 Plicated rocks, effects of erosion of, 186* Plication of clayey layers, 208, 209* Plications and plicating, experi- ments by Daubree on, 353; in mountains, 354 Plicatula inflata, 866 ; placunea, 837, 865 ; spinosa, 790 Plinthosella squamosa, 432* Pliocene period, 880 Pliohippus, 913*, 919 Pliohippus beds, 885 Pliopithecus, 927 Pliosaurus, 785 Plocoscyphia maeandrina, 866 Plombieres, formation of zeolites at, 323 Plover, 902 Plum, 921 Plumbaginous rock. See Graphitic Plumbago, 62 Plutonic rocks, 298 Pluvial period, 981 Pnesopteryx, 1014 Po, ratio of sediment to water, 190 Pocono group, 410, 634, 636, 728 Podosthenic, 439, 717, 726, 796 Podozamites Emmonsi, 749* ; lance- olatus, 833* ; nervosus, 834 Podura, 419, 702 Poebrotherium, 911, 918 ; labiatum, 910, 911* Poecilodus, 692 Pogonip limestone, 495, 516 Pogonodon, 918 Poikilitic group, 631, 7S8 Polacanthus Foxi, 868 Polar Bear, 950 ice-cap, 346 Polenos Island, 296 (volcanoes) Polioptenus elegans, 704 Polishing of rocks. See Scratches Pollinices Burnsii, 917 Polycystines, 433* Polyernus, 691 Polygnathus dubius, 621 ; nasutus, 621 ; palmatus, 621 ; princeps, 621 ; punctatus, 621 Polymastodon, 917 Polynesian chain of islands, 37*, 38, 39 Polyonax, 847 Polyps, Polyp corals, 144, 419, 429*, 431 Polypterus, 59, 417 Polyzoans, 427 Pomeroy coal-bed, 653, 654, 689 Pompeii, 280 Ponderosa marls. See Exogyra pon- der osa marls Ponent series, 728 Pontian stage, 927 Popanoceras, 686 Poplar, 837-, 922 Popocatapetl (Mt.), height of, 937 Populus laevigata, 839; mutabilis ovalis, 839; Nebrascensis, 889 primseva, 833 Porambonites, 521 Porcelain clay, 81, 184, 638 ; jasper,, 84 Porcelanyte, 84 Porcellio, 420* Porcupine, 798 Porcupine Hills beds, 830 Porifera, 431 Poroblattina, 691 Porocrinus, 514, 516 Pororoca, 212, 215 Porous rocks, 328 Porphyritic rocks, 77*, 83, 824 Porphyry, 84, 341* Porphyryte, 86 Port Hudson clay, 198 Port Jackson, E". S. W., cliffs at, 221* Port Jackson shark, 643, 797 Portage epoch and group, 576, 602 sandstone, 603, 605 Porte Blanche, 248 Portheus, 844*, 862; molossus, 848 Portland beds, England, 788, 777; dirt-bed, 775, 776* cement, 79 Portland Oolyte, 411, 775 ; stone, 775 Portland, Victoria, 34 Portlandian group, 738, 775 Portsdown axis, 936 Portugal, 85; Cambrian in, 484; Lower Silurian, 521 Posidonomya, 756; Bronni, 790; venusta, 627 Post-Pliocene, 940, 941 Post-Tertiary, 940 Pot-holes, 184, 250, 949 Potamides transsectus, 916 Potash, 61, 81 ; salts, 320 Potassium, 61 Potentilla, 240 Poteriocrinus, 532, 646, 690; Cox- anus, 640 INDEX. 1075 Potomac group, 816 Potosi, 26 Potsdam period, Potsdam Sand- stone, 463, 464 Potter's clay, 81 Pottsville coal-beds, 650, 656 conglomerate, 64T Powder Eiver, 266 Pozzuolana, 80 Prsearcturus, 623, 624 Prasopora lycoperdon, 505*, 514 Prawn, 438 Precession of the equinoxes, 258 Prehnite, 68 Preston beds, 817, 836 Prestwichia, 701, 720 ; anthrax, 703 ; Danaa, 977*, 691 ; longispina, 691; rotundata, 701*, 703 Priacodon ferox, 767* Priconodon crassus, 836* Primal of Rogers, 490, 728 Sandstone, 463 Primary, 408, 880 Primates. See Quadrumana Primitia, 481, 516 Primitive system, 408 Primitivgebirge, 440 Primordial, 462, 464, 482 Prince Edward Island, 357, 741; Permian in, 660; Triassic, 753, 755 Prince Patrick Island, 749, 760, 792 Prince William Sound, 240 Prioniodus acicularis, 621 ; angula- tus, 621 ; armatus, 621 ; erraticus, 621 ; spicatus, 621 Prionocyclus, 855 ; Woolgari, 855 Prionotropis, 855 Pristis bisulcatus, 925 Proboscideans, 919 Procamelus, 911, 919 Prodryas Persephone, 900* Productella, 611, 612 ; hirsuta, 621 ; lacrymosa, 613*, 621 ; navicella, 590; pyxidata, 602; speciosa, 620 ; subaculeata, 585* ; subulata, 598*, 601, 602 ; truncata, 602 Productus, 309, 427*, 591, 592, 642, 674,^700, 705-, -707 ; aculeatus, 427* ; Cancrini, 704 ; cora, 690 ; costatus, 606, 704; dissimilis, 602; Fle- mingi, 646; horridus, 704, 707; lacrymosus, 592 ; latissimus, 704 ; Leplayi, 704; longispinus, 700*, 704, 711 ; mesolobus, 606 ; muri- catus, 690; Nebrascensis, 675*, 690 ; Norwood!, 685 ; parvus, 647 ; prselongus, 626 ; punctatus, 642*, 690, 704; Rogersi, 685; scabri- culus, 703, 704; scitulus, 646; semireticulatus, 427*, 685, 690, 711; Shumardianus, 602; spe- ciosus, 592 ; subaculeatus, 626, 627, 628 Proetus, 513, 515, 521, 552, 562, 568, 579, 586, 591, 643, 720 ; auriculatus, 614; crassimarginatus, 587*, 591, 599 ; doris, 614 ; Girvanensis, 520 ; latifrons, 565*, 567 ; minutus, 614 ; parviusculus, 516 ; precursor, 14 ; Stokesi, 551, 567, 569 Proganochelys Quenstedtii, 773 Progonoblattina, 691 Progress in earth's development, 397 Proicene, 880 Prolecanites Lyoni, 643* Promontory Eange, 365 Promylacris, 691 Propylyte, 87, 304 Prorhynchus, 621 ; nasutum, 621 Proscorpius Osborni, 557* Prosoponiscus problematicus, 707 Prospect Ridges, 495, 733 Prosqualodon, 927 Prosthenic, 717, 796, 870 Protseiphyllum, 831 Protannularia Harknessi, 519* Protapirus, 910, 918 Protaster, 516, 562 ; Forbesii, 562 ; hirudo, 567 ; Sedgwickii, 567 Protaxis, 24. See also Acadian protaxis ; Appalachian ; Archaean ; Rocky Mountain ; also Gold Range Proteacese, 921, 922 Protean group, 542, 638 Proterosaurus Speneri, 706* Protichnites septemnotatus, 478* Protoadapis, 925 Protobalanus Hamiltonensis, 600* Protocardium Hillamim, 836 Protocarids, 486 Protocaris, 720 ; Marshi, 474* Protoceras, 911, 918 Protoceras beds, 886, 894, 911, 918 Protocimex Siluricus, 520 Protococcus, 235, 436 ; nivalis, 241, 436$ Protogine, s 83 Protogonia, 917 Protogonodon, 917 Protohippus, 911, 912, 913*, 919 Protolabis, 911, 919 Protolimulus Eriensis, 615*, 617 Protolycosa anthracophila, 703 Protophasmids, 677, 679, 691, 701 Protophytes, 407 ; Corniferous, 583* ; Cretaceous, 859 ; Tertiary, 895 Protopterus, 60 Protoreodon, 907, 918 Protorthis Billingsi, 475* ProtosaMnia, 718 ; Huronensis, 584 Protospongia, 482, 497; coronata, 498*; cyathiformis, 498*; fene- strata, 474*, 481 ; mononema, 498*, 500; Quebecensis, 498*; tetranema, 498* Protostega gigas, 849 Prototarites Logani, 591 Prototherium, 795, 927 Prototype characters, 928 Protozoans, 140, 141, 407, 409*, 418, 419, 431, 432*; Archaean, 455; Lower Cambrian, 470 Protozoic, 407 Provence, Cretaceous in, 866 Proviverra, 918, 925 Provo, 360*, 361 Psammodonts, 643, 647 Psammodus, 589, 643 Psaronius, 704 ; Erianus, 595 Pseudaelurus, 919 Pseudodiadema, 779, 834; diatre- tum, 854 ; hemisphaericum, 790 ; Moorei, 790; seriale, 778*, 779; Texanum, 836 Pseudoliva, 916; scalina, 915; tu- berculifera, 915 ; unicarinata, 915 Pseudomonotis, 690 ; Hawni, 685* ; Ochotica, 758 ; speluncaria, 707 Pseudopecopteris, 699 ; anceps, 645, 689; decipiens, 689; irregularis, 689 ; latifolia, 689 ; muricata, 689 ; nervosa, 689 ; nummularia, 689 Psilomelane, 71 Psilophyton, 583, 590; cornutum, 560 ; princeps, 583*, 622 Psittacotherium, 904, 917 Pteranodon, 863 ; ingens, 852 ; lon- giceps, 849*, 852 Pteranodonts, 851 Pteraspids, 417, 557, 725 Pteraspis, 564, 625 ; Banksii, 566*, 567 ; Ludensis, 567 ; truncata, 567 Pterichthys, 566, 617, 625, 627 ; Canadensis, 611 ; cornutus, 624* ; major, 627 ; Milleri, 624* Pterinea, 621, 877 (end) ; Chemun- gensis, 613*, 621; flabella, 598*, 602 ; hians, 567 ; retroflexa, 567, 568; Sowerbyi, 567; sublaevis, 567 ; Trentonensis, 507* Pteris aquilina, 74 ; erosa, 839 Pterocerajucarinata, 865 ; oceani, 791 ; ponti, 791 Pterocerian beds, 791 Pterodactyls, 796 ; Jurassic, 776 Pterodactylus, 788, 790; crassiros- tris, 786*, 788 ; montanus, 767 Pterodon, 918 PterophyUum, 698; Jaegeri, 770*, 774 ; Riegeri, 749* Pteropods, 59, 72, 141, 144, 423, 424, 425* ; Cambrian, 469, 472*, 475*, 478*, 480, 483 Pteropsis Conradi, 897*; lapidosa, 916 Pteropus, 53 Pterosaurs, 796, 877 ; Jurassic, 760, 767, 787*, 788; Cretaceous, 844, 851, 852, 863, 870, 871, 876 (end of tribe) Pterotheca, 503, 506 ; attenuata, 514 Pterygotus, 557, 565, 722, 724; acuticaudatus, 557 4 Anglicus, 623* ; bilobus, 564*, 567 Ptilodictya, 514, 521, 550; scalpel- lum, 567' Ptilodus, 917 Ptilophyton plumula, 645 (last of the genus) Ptychaspis speciosa, 501 Ptychites, 686 ; gibbosus, 774 Ptychoceras, 855 ; Texanum, 855 Ptychodus mammillaris, 855; Mor- toni, 843* Ptychoparia, 500, 516; Adamsi, 473*; Calcifera, 501; formosa, 476* ; Hartti, 501 ; Kingi, 476* ; Matthewi, 476* ; minuta, 479* Ptychopteria, 621, 638 ; falcata, 621 ; Sao, 621 Ptyonius serrula, 682, 683* 1076 INDEX. Ptyonodus, 687 Pudding-granite, 97 Pudding-stone, 80, 147 Puerco Eocene lake or basin, 881*, 882, 893 group, 886 Puerto Eico, 19 Puget group, 831 Sound, 831 Pugnellus densatus, 854 Pulaski shales, 494 Pullastra arenicola, 774 Pulmonates, 423, 674 (first), 676* Pumice, 80, 84, 136, 144, 266, 276, 892 Punjab, 770 Pupa, 152, 708 ; Blandi, 966 ; con- tracta, 966; fallax, 966; mus- corum, 966 ; quarticaria, 966 ; simplex, 966 ; Vermilionensis, 676*, 690 ; vetusta, 676*, 682, 690 Purbeck axis, 936 beds, Purbeckian, 411, 775, 777, 783, 789, 791 Purity of air and waters in the Cambrian, 484, 485 Purpura, 130 ; cancellata, 855 Purus, 867 Putnam County, N.Y., 24 Pycnodonts, 417, 836 Pycnodus, 417, 772, 783 Pycnogonids, 419 Pygidium, 421 Pygocephalus Couperi, 703 Pygopterus, 692, 705 ; mandibularis, 707 Pygurus rostratus, 865 Pyramids of Egypt, made in part of Nummulitic limestone, 920 Pyrazisinus acutus, 916 ; campanu- latus, 898*, 916 Pyrenean basin, 857 Pyrenees, 23, 239, 265, 812 ; Lower Silurian in, 518 ; Jurassic, 775 ; Cretaceous, 866; Tertiary, 347, 865, 919, 920 ; elevation of, 932, 936 Pyrifusus granosus, 855; New- berryi, 841*, 855; subduratus, 854 Pyrite, 70*, 123 Pyrites, 80 Pyritiferous rocks, 78, 84, 658 Pyromeride, 84 Pyrophyllite, 68, 89 Pyrophyllyte schist, 89 Pyroxene, 67*, 85, 86, 288* ; rocks, Pyroxenyte, 88, 532 Pyrrhotite, 70 Pytho, 847 Pythonomorphs, 826, 847 Quadersandstein, Upper, 866 Quadrumana, 54, 902, 903, 906, 907, 917 ; in Europe, 923, 925, 927 Quadrupeds. See Mammals Quakertown coal-beds, 656 Quartz, 15, 62, 63 ; work of solu- tions of, 135-136 Quartz-andesyte, 86, 273, 296; basalt, 296; dioryte, 86, 272; doleryte, 87 ; felsyte, 272, 325; gabbro, 87 ; porphyry, 84, 817 ; syenyte, 85 ; trachyte, 84, 86, 273, 314 (see also Ehyolyte) Quartz flour from glaciers, 169 Quartzophyric rocks, 77, 83, 84 Quartzose rocks, 78 Quartzyte, 80, 82, 112* (jointed) ; septaria, 138* Quartzytic rocks, 83, 84 Quaternary era, 940 ; general obser- vations on, 1016 Quebec, 466 group, 482, 490, 496, 497, 503, 527* Queen Charlotte Islands, 747, 757, 760, 809, 818, 830, 868 Queensland, 698, 699 ; Devonian in, 628 ; Jurassic, 776 ; Cretaceous, 857 Quenstedioceras cordiforme, 758*, 760 Quercus, 840, 921, 922 ; angustiloba, 839; castanopsis, 839; Ellisiana, 839 ; Godeti, 839 ; myrtifblia, 895*, 896; suber, 713 Quercy phosphorite beds, 926 Quetta, earthquake in 1892, 375 Quicklime, 78, 79 Quicksilver mines, 335 Quito, plateau, 26; volcanoes of, 296 Eacket Eiver, 946 Eacodiscula, 432* Eadack Islands, 36, 38, 39, 145 Badiates, 419 Eadiolarian earth, 935, 936; ooze, 144 Eadiolarians, 57, 64, 72, 121, 136, 141, 144, 433* ; Archaean, 1029 Eadiolite limestone, 866 Kadiolites, 820, 861, 877; Austin- ensis, 855 ; Bournoni, 861* ; Mor- toni, 861; Neocomiensis, 865; Texanus, 834, 835*, 836 Eadula acutilieneata, 854 Eafinesquina, 503, 579; alternata, 507*, 514, 524; fasciata, 503; incrassata, 503 Eaft of Bed Eiver, 191 Eagadinia annulata, 432* Eaibl shales, 774 Eain, causes influencing the amount of, 50, 51 Eain-drop, work of, 177, 178* Eain-prints, 95, 178, 223, 645, 742 Eain fall, 51, 944, 945 Eainier, Mt. See Tacoma Eainy Lake, 446 Eajmahal group, 698, 873 Ealick Islands, 36, 38, 39, 145 Eancocas group, 821 Eangifer caribou, 946, 1002 ; taran- dus, 946 Eanunculus, 240 Eaphistoma, 506, 520, 521 ; lenticu- lare, 507*, 514, 524, 567; multi- volvatum, 501 ; Pepinense, 501 ; planistrium, 508 Eappahannock freestones, 816 Earitan beds (group), 815, 821 Eat, 58, 156, 797 Eaton coal-field, 364 Eaton Mts., 828 Eattan, 435 Eattlesnake, 682 Eauchwacke, 697 Eauhkalk, 697 Eauracian group, 790 Eays, 415, 418 Eazor stone, 88 Eecent period, 1012 Eeceptaculites, 497*, 513, 515, 516, 560, 584, 597; elegantulus, 497*, 500 ; globularis, 513 ; infundibuli- formis, 562 ; lowensis, 513 ; Nep- tuni, 517, 524, 569; Oweni, 513, 515 Eed Bluff group, 889 Eed Crag, 927 Eed Deer Eiver, 847 Eed earth, 134 Eed marl, 542, 627 Eed ocher, 70, 126, 331 Eed porphyry, 86 Eed Eiver, 191 (raft), 819, 885, 888,. 895 Eed Eiver of the North, 947 Eed Sea, 21, 41, 200 ; volcanoes of, 295, 296 Eed Wall Group, 469, 658 Eedwood, 831, 859, 939 Eegelation, 245 Eeindeer, 946, 950, 1013 Eeindeer or Mesolithic epoch,. 997, 1009 Eemopleurides, 520, 521 Eensselferia, 562, 578, 579 ; ovoides, 578*, 579 Eensselaerite, 320, 453 Eeptiles, 54, 55, 414 ; reign, or era of, 737 ; Permian, 687, 706, 726 : relation to Birds, 794, 795 Eequienia, 877 (end of genus) ; am- monia, 865; Lonsdalei, 865; ob- longa, 865; patagiata, 836; Texana,. 834, 835*, 836 Eesins, 74, 143, 712, 713 Eespiration, 136 Eeteocrinus, 516 Eetepora, 427 Eetzia, 627 Ehabdoceras Eusselli, 757 Ehabdoceras bed, 757 Ehacophyllites, 760 Ehacophyllum, 699 ; Brownii, 611 ; filiciforme, 689, 705 ; flabellatum, 645 ; lactuca, 689, 693, 705 Ehadinichthys, 692 Ehaetic beds^ 738, 769 Ehamnus Goldianus, 839 ; rectiner- vis, 839 ; salicifolius, 839 Ehamphorhynchus, 788, 790 ; phyl- lurus, 787*, 788 Ehea, 54 Ehenan beds, 626, 627 Ehine, 169, 176, 191 (denudation), 195 (loess), 570 Ehinoceros, 54, 902, 907, 909, 910, 911, 927, 928 ; Etruscus, 927 : hemitoachus, 1005, 1006; incisi- vus, 927 ; megarhinus, 927 ; pro- terus, 1001 ; Schleiermacheri, 927; tichorhinus, 1004, 1005, 1006 INDEX. 1077 Khizocarps, 435, 436*, 584, 611, 718 Rhizocrinus, 59 Rhizodus, 417, 692 Rhizopods, 56, 72, 140, 432*, 817 ; Archaean, 454, 455 Rhodanian, 859, 865 Rhode Island, mean height of, 23 ; coal-beds of, 634 Rhodocrinus, 597 Rhone, slope of river, 178; dis- charge of detritus by, 190 valley glaciers, 235*, 238, 242 Rhotomagian, 859, 866 Rhus, 921 Rhynchocephalia, 54, 687, 706, 795, 856 Rhynchodus secans, 589* Rhyncholites, 424 \Rhynchonella, 425, 426*, 516, 517, 520, 550, 552, 562, 568, 579, 642, 700, 719, 756, 757 ; acutirostris, 503 ; affinis, 568 ; altilis, 503 ; bi- dentata, 569; capax, 507*, 514; castanea, 592; compressa, 865; concinna, 790, 791 ; contracta, 613*, 621 ; corallina, 790 ; cuboides, 593, 601, 622, 625, 627, 628 ; Cuvi- eri, 866; decorata, 790; dubia, 503 ; duplicate, 592 ; eximia, 620 ; inconstans, 779 ; Laura, 592 ; Mar- tini, 866 ; navicula, 567 ; neglecta, 551, 567; nobilis, 562; nucula, 567 ; oblata, 579 ; obsoleta, 790 ; orientalis, 503 ; Petrocorriensis, 866; pigmaea, 790; plena, 502*; pleurodon, 628; plicatilis, 866; psittacea, 426*, 984 ; pugnus, 620, 628; semiplicata, 562; sinuata, 592 ; socialis, 790 ; speciosa, 579 ; spinosa, 790 ; Strickland!, 567, 569, 573 ; subangulata, 790 ; tripar- tita, 520 ; variabilis, 791 ; varians, 790 ; ventricosa, 560*, 562 ; Wil- soni, 562, 567, 569, 573 Rhynchonellids, 922 Rhynchophora, number of Floris- sant, 900 Rhynchosaurus, 773 Rhynchotreta cuneata, 548*, 551, 569 Rhyolyte, 84, 87, 272, 273, 276 Rhytina Stelleri, 1015 Richmond (Va.) basin, 358, 742, 756 ; coal areas, 743, 755 ; infusorial earth, 894*, 895; Triassic area, 740, 741, 743, 799 Ridges, 28* Riffelhorn, 248 Rill-marks, 95*, 538 Rimella, 916 ; laqueata, 916 ; Tex- ana, 916 Ringgold and Rogers Exploring Ex- pedition, 927 Ringicula biplicata, 916 Rio de la Plata. See La Plata Rio Grande, 817, 819, 855, 885 Ripley epoch or group, 815, 821, 840. 854, 873 Ripple-marks, 13, 89, 94, 95*, 161, 223 ; Cambrian, 464, 484 Risaoa Chastelii, 926 River systems, 28, 29, 30 valleys, excavation of, 178 ; buried, 204, 934 waters, analyses of, 121 Rivers : lengths and drainage areas, 30, 172, 173 ; special points in fluvial history, 203-204; trans- portation and deposition by, 189- 202 ; distribution of transported material, 191 ; velocity of, 175" ; working-power of, 173-177 Roan Mts., 901, 946 Robinia, 921 Roche-Moutonnee Creek, 250* Roches moutonnees, 250* Rock-cities, 604, 647 Rock-flour, 81, 248, 251, 941 Rock-making, 140 Rock salt, 320, 552, 553, 554, 769 Rockford shale, 606 Rocks : constituents, 61 ; kinds of, 75; organic constituents, 71-75, 140-141, 458 ; structure, 90 ; ex- pansion, 259 , volcanic. See Volcanic Rockwood beds, 577 Rocky Mountain Chain, 389, 748; protaxis, 24, 444, 461, 464, 483, 490, 746; silver and lead mines, 876 Rocky Mountain region, Archaean in, 444; Cambrian, 464; Lower Silurian, 494, 495; Upper Silu- rian, 541 ; Devonian, 575, 581 ; Glacial, 944 ; Subcarboniferous, 639; Carboniferous, 634, 635, 658; Triassic and Jurassic, 808- 812; Cretaceous, 814, 815, 818, 827, 829, 838, 868, 880 ; Tertiary, 882, 887; elevation during, 933, 935 Rocky Mts., 24, 31*, 51 ; glaciers of, 240 ; changes of level in, 347 ; making of Laramide Mts., 874; volcanoes of, 296, 937 Romingeria, 579; cornuta, 584*, 590 Roofing-slate, 80, 92, 112, 113*, 370, 871 Roots, acidity of, and the corroding effects, 136 ; destruction by, 157* Rosa, Monte, glacier region of, 236, 287,248 Rosendale cement, 555 Rossberg landslide, in 1806, 208 Rosso antico, 86 Rostellaria, 922 ; nobilis, 854 Rota Island, elevation of, 350 Rotalia Boucana, 432*; globulosa, 432* Rothliegende, 697, 706 Rotifers, 423, 455 720, 721 Rotomahana Lake, 305 Rotten limestone group, 815, 823, 824, 848, 854 Rubidium, 335, 449 Ruby, 64 Rudistes, 840, 841*, 854, 861* Rupelian beds, 926 Rurutu Islands, 37 ; elevation of, 850 Rusophycus bilobatus, 545*, 546 Russia, 34, 167 ; upturnings in, 630, 734 , Cambrian in, 482, 484, 518 ; Lower Silurian, 518, 521, 588; Upper Silurian, 533, 563, 566, 567, 568, 569, 573; Devonian, 627; Subcarboniferous, 693, 696, 704 ; Carboniferous, 690, 693, 697, 710 ; Permian, 686, 697, 707 ; Tri- assic, 768; Jurassic, 760, 775, 776, 790, 794; Cretaceous, 857; Tertiary, 923 Rutoceras, 591, 602 Ruwenzori, Mt, 33, 296 (height) Sabal, 837, 921 ; major, 933 Sabine River, 889, 890 Sable Island, 444, 944 Saccammina Carteri, 700 Saccosoina pectinata, 778*, 779 Sacramento River, 30, 809; valley, 749, 811, 818, 820, 830, 895 Saganaga Lake, 448 Sageceras, 756 ; Haidingeri, 757* Sagenaria acuminata, 646 Sagenopteris, 698, 704 Saghalien, 40 Saguenay River, 948 Sahara, desert of, 51 ; plateau of, 26,34 St. Cassian beds, 769, 774 St. Elias, Mt., 25, 238, 239*, 240 (glaciers), 251, 390 St. George's Shoal, 881, 889 St. Gothard tunnel, fossils, 310 St. Helena, volcano of, 290, 297 St. Helens Island, 531, 558 St. Helens, Mt., 296, 945 St. John, N.B., elevation, 350 St. Lawrence Bay, 461, 541, 544 channel, 536, 571 Gulf, 444, 533, 537 ; coal making in, 708 River, 40, 171, 536; depth of, 948 valley in the Champlain period, 982 St. Louis limestone, 634, 687, 688, 646, 647 St. Mary River series, 880 St. Paul's Island, 867 St. Peter, Lake, 542 St. Peter's Island, 867 sandstone, 136, 491, 498, 494, 782 St. Vincent Island, 168 Salamander, 415, 920 Salenia, 840, 860 Salina beds, 552 Saline deposits, 119 ; efflorescences, 138, 160 ; springs, 200, 553 Salinity of the ocean, 121, 214 Salisburia, 53, 435; nana, 883; Sibirica, 833* Salix, 854, 922 ; angusta, 839 ; Meekii, 837, 838* Salmon. 812, 879 ; family, 862 Salt, 63 (see also Rock salt) ; lakes, 119, 881 ; making, 120 ; pans, 120, 133, 134, 554, 791 ; water, subter- ranean, 320 Salt Lake City, 360*, 361 Salt Range, India, 483, 698, 770, 776 1078 INDEX. Salt-works of Salina, 553, 554 Salterella, 471 ; Billingsi, 515 ; Mac- cullochi, 573 ; pulchella, 471, 472* ; rugosa, 578 Salton Lake, 200 Saltonstall Ridge, 801* Saltpeter, 63, 137 Salvinia, 584, 718 ; natans, 435, 436* Samoan Islands, 36, 88, 145, 283, 297 San Bernardino, Pass of, 160 San Francisco Mountains, 660; peninsula, 884, 892 ; Eiver, 885 San Gabriel Range, 892 San Juan Mts., 363 Sand, 75, 76 ; barriers, 223, 224* ; bars, 192, 193, 202, 212, 216, 225, 226*, 227*; hills on sea shores, 94, 155, 161, 162; rock, 80; scratches, 160 ; spits, increase of, 223, 224 Sand-blast, carving by, 161 Sand-flea, 420*, 421 Sand-worm, 423 Sandstone, 80; dikes or veins, 344*, 811, 876 Sandstones of Condros, 625 Sandusky limestone, 581 Sandy Hook, formation of, 224, 225 Sangay, 26 Sangre de Cristo Range, 266 Sanidin, 84, 88 ; trachyte, 84 Sannionites, 501 Sannoisian stage, 926 Santa Cruz beds, 927 ; Islands, vol- canoes of, 296 ; Mts., 892 Santa Inez Range, 892 Santa Lucia Mts., 892 Santa Maria Island, elevation of, 849 Santa Monica Range, 892 Santa Suzanna Range, 892 Santee beds, 888 Santo Domingo, 19, 935 Santonian, 859, 866 Santorin Island, 296 (volcanoes) Sao hirsuta, 481*, 482 Sao Miguel, geysers of, 308 Sapindus, 838, 896 ; Morrisoni, 838 Saportsea, 685 Sapphire, 64 Sapphirina Iris, 420*, 421 Sarcinula, 640 ; obsoleta, 511*, 515 Sardinia, Cambrian in, 482 ; Upper Silurian, 563, 564 Sargasso Sea, 45, 121, 148, 156 Sargassum, 437 Sarmatian stage, 927 Sarotes venatorius, 168 Saskatchewan River, 29, 203, 947 Sassafras, 812, 831, 837, 879, 921 ; Cretaceum, 837, 838* Sat valley, 240 Saurichthys, 772 ; apicalis, 774 Saurocephalus, 862 ; lanciformis, 844 Saurodon lanciformis, 844 Saurodonts, 826, 843, 862 Sauropods, 761, 762-764, 786, 867 Sauropus primaevus, 645* Saussurite, 65, 88, 318, 319 ; rocks, 82,88 Sarage Island, elevation, 350 Savaii, 283 Saxicava, 157; arctica, 983, 984; rugosa, 984, 995 Saxifraga, 240 ; oppositifolia, 945 Saxony, Archaean in, 455, 456 ; Per- mian, 706, 707 ; Triassic, 768 Scalaria, 916, 922; Bowerbankii, 925 ; Groenlandica, 984 ; Hercules, 854 ; Sillimani, 854 Scalent series, 728 Scales, Fish, analysis of, 73 Scalites angulatus, 502* Scandinavia, 32, 43, 256; fiords of, 948; Archaean in, 456; Cam- brian, 482 ; Lower Silurian, 521 ; Upper Silurian, 563, 568, 569, 573; Cretaceous, 857; Glacial, 948. See also Norway ; Sweden ; etc. Scandinavian plateau, 19 Scaphaspis Ludensis, 567 Scaphiocrinus, 646, 690 ; Missouri- ensis, 640*, 646 Scaphites, 854; aequalis, 866; Con- radi, 842*, 854, 855 ; Geinitzi, 866 ; hippocrepis, 854 ; larvaeformis, 842*, 843, 855 ; nodosus, 855 ; pul- cherrimus, 866 ; Texanus, 855 ; ventricosus, 855 ; vermiformis, 855 Scaphodus Ludensis, 567 Scaphopods, 424 Scapolite, 65, 79, 310, 818, 820 Scar limestone, 695 Scaumenacia, 621 Scelidosaurus, 787 Scelidotherium, 1003 Scenella, 482 ; reticulata, 472* ; re- tusa, 472* Schillerization, 321 Schist, 83, 84 Schistose rocks, 82, 83 Schistosity, 113, 371 Schizaster atavus, 866 Schizobolus truncatus, 612 Schizocrania filosa, 507*, 514 Schizocrinus, 532 ; nodosus, 514 Schizodus, 602, 621, 687, W ; am- plus, 690; Chesterensis, 647; dubius, 707 ; obscurus, 707 ; quadrangularis, 620 ; Rossicus, 685 ; Schlotheimi, 707 ; truncatus, 707 Schizopods, 439, 703 Schizotherium, 918 Schlern dolomyte, 774 Schkenbachia Belknapi, 836; cris- tata, 865 ; dentato-carinata, 855 ; inflata, 865; Peruviana, 886; varians, 866 ; varicosa, 865 Schlrenbachia clays, 836 Schoharie epoch, 410, 576, 579 ; grit, 576, 579, 587, 590, 591, 601, 628 Schorl rock, 88 Schuylkill River, 816 Scirpus, 75 ; caespitosus, 946 Sciurus, 910, 918 Scolithus, 428, 470 ; linearis, 477* Scolopendra, 419, 724 Scoria, 266, 267, 281*, 282 Scoriaceous lavas, 280, 281*, 298 ; rocks, 78 Scorpions, 420, 564, 722, 724; Upper Silurian, 556, 565, 574, 722; Devonian, 575; Carbon- iferous, 677, 691, 701* Scotland, 155, 218, 229, 258, 288, 453, 534; Archaean in, 453, 456, 457; Cambrian, 457, 481 ; Lower Silurian, 518, 520, 524; Upper Silurian, 563, 565, 573; Devo- nian, 622, 623, 625 ; Subcar- boniferous, 695 ; Carboniferous, 702, 703 ; Permian, 697 ; Triassic, 768, 773; Jurassic, 775; great thrust movement in Highlands of, 534 Scratches, 95, 96 Scratching by drifting sand, 160; by icebergs, 252; by slides of rock, 249* Scutella,559 > Scutella limestone, 559 Scyphia digitata, 513 Scyphian-Kalk, 790 Sea-anemone, 431 Sea bottom, changes in level of, 345, 348, 949 Sea water, salts of, composition of, 120 ; dolomization by means of, 134 Seals, 415 Seam, 92 Seaweeds, 56, 75, 143, 155, 436 Secondary formations,738; minerals, *320, 323, 332, 340, 341; rocks, 408, 880 Secretary Bird, 923 Section, general, of geological series, 410*, 411* of Adirondacks, Can., 452* ; Appalachians, 102*, 109*, 355*, 356*; Arch;ean, 451*; Bald Mt., N. Y., 528* of Coal-measures at Trevorton Gap, 650* ; Coal-measures near Nesquehoning, 649* of Colorado Plateau, 110*, 363* ; Cumberland Table-land, Tenn., 356* of Dent de Morcles, 367* ; Mt. Eolus, Vt., 530* ; at Genesee Falls, 91*, 542; of Greylock Mt., Mass., 530* of Hamilton beds, Lake Erie, 594*; Hawaii, 269*; Himalayas, 82*, 368* ; Jura Mts., 368* of Mt. Loa, 286* ; of Portland dirt-bed, 776* ; at Niagara River, 540* ; of Paleozoic at Pottsville, 650* (Prosser's) of New York rocks near Rochester, 605; (Prosser's) of Pennsylvania rocks, Munroe Co., 594, 606 - on the Schuylkill, Pa., 650*; of Snake Mt., Vt., 528*; Taconic Range, near Montmorenci Falls, 527* ; Tennessee Rocks, 856* ; Timpahute Range, 366*; Utah ore-beds, 339* showing cavern-making in lime- stone, 130*; of decaying lime- stone, Amenia, N.Y., 126 INDEX. 1079 Section of Alps, 102*, 110* ; Car- bonate Hill, Leadville, 341*; Coal-measures, 651-662, 656, 657 ; Kilauea, 284*, 285* of Laramide Mountain range, Brit. A., 359* Sediment, 76, 167 ; ratio of, to water, 190 Sedimentary rocks, 167 ; sedimen- tation more rapid in salt water than in fresh, 209, 210, 217 Sedum rhodiola, 945 Seeds, transportation of, 156, 168 Seiches, 202 Seine, 191 Seismograph, seismometer, seismo- scope, 375 Selachians, 415, 416* Selaginella, 718 Selenium, 331 Selkirk Mts., 240 Selvage, 332 Semele Stimpsoni, 927 Seminula subtilita, 675*, 685, 690 Semi-oviparous Mammals, 415 Senonian group, 815, 858, 859, 860, Sepia, 424 Septaria, 97*, 188* (quartzyte) Sepulchre Mt., 937 Sequanian group, 790 Sequoia, 816, 831, 837, 840, 859, 921, 939 ; ambigua, 838 ; gigantea, 939 ; gracilis, 834 ; Langsdorffi, 921 ; Reichenbachi, 834, 839 ; Smittiana, 833*, 834 Serai series, 728 Sergestes mollis, 52 Sergipian group, 867 Sericite, 65 ; schist, 84, 88, 89 Sericitschiefer, 84 Series, 406 Serolis, 420* Serpentine, 68, 319 Serpula, 423 Serpulidae, 59 Serpulites dissolutus, 515 Serripes Groenlandicus, 983, 984 Sertularia, 430* ; abietina, 430*; rosacea, 430* Sevier Lake, 119 Sewickley coal-bed, 651 Seychelles Islands, 737 Shakopee limestone, 498 Shale, shaly structure, 80, 92 Shan-a-lin Mts., 32 Shan si, 696 Shan-Tung, 198 Sharks, 56, 60, 73 (analysis of bones), 415, 416* ; teeth of, dredged, 144. See Selachians Sharon coal-beds, 656; conglomer- ate, 648, 656 Shasta, Mt., 87, 267*; glaciers of, 240, 945 ; height of, 296 group, 818 ; Aucellae of, 834 Shasta-Chico series, 809, 815, 820, 830, 868 Shawangunk grit, 538, 539, 541 Mts., 538, 946 Shawnee coal-bed, 828 Shear-zones, 111, 322 Shearing, 168, 216, 322 Sheep-backs, 250* Shell-beds or heaps, 98, 158; of Maine, 983, 994 Shell Bluff, Ga., 916 Shell-limestone, 79, 151 ; marl, 79 Shenandoah valley, 357 Shenango group, 638 Sheppey, Isle of, 921, 923, 925 Sheridan, Mt., height of, 296 Shetlands, 87, 218 Shinarump Cliffs, 747 Ship worm, 158 Shoal Creek limestone, 817 Shore-lines, elevated, in region of Great Lakes, 906; about Lake Winnipeg, 985 Shore-platforms, 220, 221*, 222* Shoshone Lake, 200,- 305 Range, 366, 945 Shot, angle of rest of, 165 Shrimps, 420, 438, 615* Shrinkage cracks, 94*, 464 Siam, 22 Siberia, 32, 166, 195, 776, 794, 833, 927 Sicily, 296, 431, 921 Siderite, 69, 126, 344, 449, 664, 665 Sierra Blanca, 874 Sierra Chain and System, 365, 389, 811 Sierra de Salina, 892 Sierra Madre, 444, 758 Sierra Nevada, 25, 27 ; buried river valleys, 204; volcanoes of, 296; river systems of, 934; glaciers of, 240 ; upturnings at close of Jurassic, 809, 814; elevation in the Tertiary, 366, 932 , Archaean in, 444; Upper Silu- rian, 810 ; Carboniferous, 635, 659; Triassic, 746, 747, 758, 809; Triassic and Jurassic, 739, 809; Jurassic, 358, 748, 760, 809 (close of), 810, 932 ; Tertiary, 366, 883, 887, 892, 895, 934 (elevation), 935, 937 (eruptions) ; Glacial, 945 Sierra San Carlos, 820 Sigillaria, 611, 639, 654, 667, 668, 682, 689, 698, 699; Brardii, 689, 693, 705; Halli, 595*; Lescurii, 689 ; mammillaris, 689 ; Menardi, 689 ; monostigma, 689 ; palpebra, 622 ; Pittstonana, 668*, 688 ; Silli- mani, 668*, 688; tesselata, 689; Vanuxemi, 609* Sigillarids, 698, 712, 718, 750 ; Car- boniferous, 669, 670, 672, 688; Coal-measure, 653 ; Permian, 684, 704, 718 (last) Silene, 240 ; acaulis, 945 Silesia, 88; Coal-measures in, 696, 702, 708 Silica, 62, 63, 135-136 ; as a solidi- fier, 323 Silicates, 62, 63, 64-68 Siliceous deposits, 82, 152, 305, 306, 808, 309, 335, 441 Claiborne, 885, 888" group, Tenn., 638 Siliceous organic rock-material, 72 r 140, 141 rocks, 80, 81, 82 ; slate, 82 solutions, 82, 94, 97 sponges, 431 Silicified wood, 125, 185 Silicon, 62, 63 ; fluoride, 66 Sillery sandstone, 467, 496 Sillimanite, 319 Silt, 81 , 150, 167, 177, 190, 198, 628; of rivers, amount of, 190 Silurian, 535 and Cambrian, history of the terms, 463, 464, 489 , Lower, 489 ; European, 517 ; economical products, 522; gen- eral observations, 524; the Cin- cinnati uplift at close of, 387, 532, 537 , Upper, 535 ; foreign, 563 ; gen- eral observations, 570 Siluric era. See Silurian Siluroids, 843 Silver Canon, 366* Silver Cliff, 340 Silver-moth, 702 Silver Peak, 469 Silverado, 733 Simeto, erosion of the, 184 Simoceras, 793 Simosaurus, 773 Sind, 299, 770, 925 Sindree, changes of level at, 849 Sineraurian group, 775; (Lower), 790 Singala Mt., 368* Sinopa, 918 Sinter, 82 Sinupallial, 425 Sioux quartzyte, 468 Siphocypraea problematica, 917 Siphonaria Penjinae, 927 Siphonema, 503 Siphonia lobata, 860* Siphonotreta, 521 ; unguiculata. 427* Sitomys, 918, 919 Sivatherium, 927 Siwalik Hills, 923, 927, 988 (Tertiary beds), 936 Skiddaw slates, 517, 519, 520 Skye, 938 Slate, 83, 92 ; siliceous, 82 Slates, auriferous, 748, 759, 809 Slaty cleavage or structure, 77, 92, 112, 113*, 370, 371 Slaty Peak, Col., height of Creta- ceous rocks, 935 Slaty rocks, 66 Slickensides, 96, 108, 111 Slimonia, 567 Slope of loose materials, 165 of mountains, 26, 27* ; of Eocky Mts., 26* Sloth, 54 Smaragdite, 88 Smilax, 435 Smilodon, 1000 Smithsonite, 342 Snails, 424, 425* Snake Mt., fault at, 527, 528* Snake River, 300, 805 ; plains, 988 1080 LNDEX. dnakes, 415, 848; Carboniferous, 726; Cretaceous, 848, 870; Ter- tiary, 202, 901, 923 Snow-drifts, 162 Snow-line on heights, 233, 284 Soapstone, 67, 68, 89 Society Islands. See Tahitian Soda, 61 ; in plants, 74, 75 Soda-granite, 86 Soda Springs, Idaho, 746 Sodalite, 81, 85, 449, 876 Sodium, 61, 63, 120 Soil, 81 ; moved by frost, 281 Solarium ornatum, 866; planorbis, 836 ; triliratum, 916 Solemya, 602 Solen, 425, 916, 917 Solen beds, 892 Solenhofen, 776, 783, 784, 786, 788, 796, 852 Solenoceras annulifer, 854 Solenomya radiata, 690; vetusta, 590 (first known) Solenopora compacta, 514 Solfataras, 128, 265, 278, 283, 293, 295, 334 Solidification, 258, 264, 326 ; of the earth, 376 Solids, flow of, 351-852 Solitaire, 1014 Soloman Islands, 86, 38, 156 Solution, 118-122 Solva group, 481 Somma, Mt., 276, 291 Sonora, 747, 748 (gold placers), 749, 755, 756 Sorata, Mt., 27 Sorrel, 945 Souris Eiver beds, 880 South Africa, 406 ; united with In- dia, 873, 937 ; and Australia, 874, 937; no fiords, 948; Paleozoic in, 699 ; Carboniferous, 699 ; Per- mian, 698, 699, 707, 737 ; Triassic, 707, 737, 770, 773, 791 ; Jurassic, 791 ; Quaternary, 1019 South America, 16, 18 ; mean height of, 23 ; surface features of, 30 ; volcanic cones of, 274 ; elevations of, 347, 874, 877 : Cordilleras, 390 ; fiords of, 948 ; Archaean in, 442, 450; Cambrian, 483; Devonian, 627; Carboniferous, 682, 659, 693, 711; Cretaceous, 857, 867; Tertiary, 865, 456; elevation during, 927, 985; post-Mesozoic mountain-making, 874 ; Glacial, 948 South Carolina, mean height of, 23 ; phosphatic deposits of, 153 ; earthquakes of, 373 South Dakota, mean height of, 28 ; Cambrian in, 464, 468, 476 ; Nia- gara, 541; Cretaceous, 828, 838, 856 ; Tertiary, 909 South Mtn., Pa., 465, 532 South Park, 495, 886, 898 South Shetlands, 296 (volcanoes) Spjtin, plateau of, 26 ; volcanoes of, 296; Cambrian in, 484; Lower Silurian, 518 ; Upper Silurian, 568, 573 ; Subcarboniferous, 693 ; Car- boniferous, 693; Jurassic, 775, 793 ; Cretaceous, 857 ; Tertiary, 920, 982 Spalacodon, 926 Spalacotherium, 789* Spanish Peaks, 296, 318, 876 Sparnacian group, 925 Spathiocaris Emersoni, 620, 621 Species, difference in, attending dif- ference in environment, 402 Specific gravity in relation to fusi- bility, 304 Specular iron, 70, 88, 578; rocks, 83 Speeton Cliffs, 865 Sperm Whale, 912 Spermatophilus Eversmani, 156 Sphserexochus, 521 ; mirus, 520, 565* ; parvus, 503 Sphseriurn, 152, 856 Sphaeroceras, 760 Sphaerocystites, 562 Sphaerophthalmus, 481 Sphaerospongia, 596 ; tesselata, 597*, 601 Sphaerozoum orientale, 433* Sphaerulites, 861 ; Hceninghausi, 861* ; Texanus, 836 Sphagnum, 73 (ash), 153; com- mune, 74 Sphalerite, 70, 125, 333, 340, 542, 687 Sphenacodon, 688 Sphene, 67 Sphenella glacialis, 699 Sphenodiscus lenticularis, 854 ; pleurasepta, 855 Sphenodon, 687 ; punctatum, 54 Sphenolepidium, 831 ; Virginicum, 834 Sphenophyllum, 639, 671, 685, 698, 699, 704 ; antiquum, 622 ; emargi- natum, 689; filiculme, 692, 693; longifolium, 689, 704; Schlot- heimi, 671*, 689 ; vetustum, 583* Sphenopteris, 639, 671, 685, 689, 693, 698, 699, 704 ; arguta, 791 ; cristata, 645; flaccida, 626; fur- cata, 689; Gravenhorstii, 670*, 689; Grevillioides, 888; Hartti, 622 ; Hildrethi, 670*, 689 ; Hitch- cockiana, 622 ; Hoeninghausi, 622 ; Hookeri, 626 ; Humphriesiana, 626; Mantelli, 831, 882*; Schim- peri, 704 ; spinosa, 689 ; tridactyl- ites, 689 ; Valdensis, 834 Sphenopterium obtusum, 646 Sphenotus, 621 ; contractus, 621 Spherophyric, 77 ; rocks, 83, 84 Spherulites, 84, 96, 97, 289, 388 Sphyradoceras, 591 Sphyrenids, 843 Spicules of sponges. See Sponge- spicules Spiders, 141, 163, 420, 525, 722, 723, 724 ; Upper Silurian, 574 ; Devo- nian, 575; Carboniferous, 657, 674, 677, 701, 722 (first) ; Paleo- zoic, 722, 723, 727 ; Tertiary, 893, 901 Spinax Blainvillii, 416* Spinel, 313, 449, 453 Spirifer, 810, 401, 425, 426*, 550, 561, 562, 568, 579, 592, 606, 642, 705, 719; acuminatus, 585*, 590, 591 ; alatus, 707 ; altus, 612 ; are- nosus, 578*, 579; arrectus, 579; asper, 602 ; bimesialis, 602 ; bi- plicatus, 642*, 646 ; borealis, 758 ; canaliferus, 625 ; cameratus, 675*, 685, 690 ; Clannyanus, 707 ; Con- radanus, 591 ; Cooperensis, 646 ; crispus, 563, 567, 568 ; cultrijuga- tus, 626, 627 ; curvatus, 625 ; cus- pidatus, 703; cyclopterus, 562, 563 ; decussatus, 626 ; disjunctus, 370*, 592, 612, 613*, 621, 622, 625, 626, 628, 703; Dumonti, 626; duodenarius, 591 ; elevatus, 567, 568; exporrectus, 520; fimbria- tus, 591, 601, 602; fragilis, 773, 774 ; giganteus, 370* ; glaber, 627 ; 700*; glaber (var. contractus), 647 ; granuliferus, 601 ; gregarius, 585*, 590, 591 ; Hungerfordi, 602 ; hystericus, 625 ; incrassatus, 704 ; increbescens, 642*, 646 ; Keokuk, 646; laevicostatus, 625; laevis, 612* ; lineatus, 690, 704 ; Logani, 646; macropleurus, 560*, 561, 562, 563; Marionensis, 602, 646; Meeki, 646; mesacostalis, 620; mesastrialis, 620 ; mucronatus, 601; Munsteri, 774; Niagarensis, 548*, 551, 563 ; Parryanus, 602 ; pennatus, 598*, 602; perlamel- losus, 562, 563; plicatellus, 520; pyxidatus, 579 ; radiatus, 522, 550, 551 ; raricosta, 592 ; speciosus, 703; striatus, 426*; sulcatus, 548*, 551, 562, 563, 567 ; Urii, 626, 627, 707 ; Vanuxemi, 558 ; vari- cosus, 592; Verneuili, 626, 627, 628 ; Whitneyi, 602 Spiriferids, 574 . Spiriferina, 756, 790 ; cristata, 707 ; Kentuckensis, 690; octoplicata, 707 ; spinosa, 642*, 646, 647 ; Wal- cotti, 779*, 790 Spirifersandstein, 570 Spirocyathus Atlanticus, 470* Spirophyton, 601, 688; caudagalli, 582*, 667, 688 Spirorbis, 675 ; arietinus, 691 ; car- bonarius, 676*, 691 ; laxus, 558 Spitzbergen, 48, 395, 758; Subcar- boniferous in, 696, 704; Carbon- iferous, 635, 696, 704, 711 ; Per- mian. 704; Triassic, 768, 774, 792 ; Jurassic, 776 ; Cretaceous, 868, 872 (climate) ; Tertiary, 922, 939 (Sequoia) Spodumene, 321, 332, 449 Spondylus, 130 ; gregalis, 854 ; spi- Sponge-beds, 777, 790 Sponges, Sponge-spicules, 57, 64, 72, 140, 141, 419, 431, 432*, 474*, 513, 515, 588*, 590, 596, 601, 611, 777, 860* Spougillae, 432 Spongiolithis appendiculata, 894* Sporangi in coal, 655* Sporangites, 601 ; Corniferous, 584 ; INDEX. 1081 Hamilton, 596; Chemung, 610, 611, 612 ; Coal-measure, 655 Sporangites Huronensis, 610, 612 Spores, 582*, 584, 611, 718 ; in coal, 654, 655*, 712 Spring Hill, 783 Springs, 205. See also Hot springs ; Mineral ; Sulphur ; Thermal waters Spruce, 435, 436, 667, 668, 770, 859 Spyroceras, 602 Squalodon, 912, 927 Squalodonts, 843*, 863, 869 Squalus cornubicus, 78 Square Lake, Me., 552, 558 Squash-bug, 419 Squid, 424*, 525, 758, 776 Squirrels, 910 Stages, 407 Stagodon tumidus, 853*; validus, 853* Stagonolepis, 778 Stags, 907, 927, 930, 1002, 1013 Staked Plains, 885, 895. See also Llano Estacado Stalactites, 79, 131, 294*, 695 ,- and stalagmites at Kilauea, 294*, 295, 324 Stalagmites, 79, 92, 131, 294* Stampian stage, 926 Stangeria, 718 Star Peak groups, 747 Starfishes, 158, 428, 429* Starucca sandstone, 606 Staten Island clay -beds, 821, 823 Statuary marble, 79 Staurolite, 65*, 66, 319, 449 Staurolitic rocks, 83, 310 Steam, 300, 338 ; in metamorphism, 312, 323, 354 3teamboat Springs, 323 ; superficial vein-making at, 334, 335 ; depos- iting gold, 335 Steatite, 67 Steatyte, 89, 450 Steel ore, 69 Stegocephs, 681, 687 Stegosaurids, 863 Stegosaurs, Stegosaurians, 761, 764, 787, 796 Stegosaurus, 765*, 787; ungulatus, 764* f^elletta, 432* Stemmatopteris, 699 ; punctata, 669*, 689 Stenaster Huxleyi, 499*, 500 Steneofiber, 918, 919 Steneosaurus, 790 Stenocrinus, 516 Stenogale, 919 Stenopora, 524 ; fibrosa, 508, 517, 567 ; Petropolitana, 517 Stenotheca, 481 ; Acadica, 475* ; rugosa, 472* Btenotrema hirsutum, 967 ; mono- don, 966 Stephanoceras Humphriesianum, 781*, 790 ; macrocephalum, 791 Stephanocrinus, 547* ; angulatus, 547*, 550 Sterculia modesta, 839 Stereocaulon Vesuvianum, 186 Stereognathus, 789* Stereosternum, 706 ; tumidum, 687 Sternbergia, 673 Sthenopterygians, 417 Stibarus, 918 Stictopora, 514, 550 Stictoporella, 505 ; cribrosa, 506* Stigmaria, 627, 645, 653, 658, 669*, 670, 699, 704; anabathra, 645; ficoides, 646, 699; minor, 645; minuta, 645 ; perlata, 622 ; pusilla, 622 ; umbonata, 645 Stikine Eiver, glaciers of, 240 Stilbite, 68 Stinkstein, 697 Stiper stones, 517 Stissing Mtn., 467 Stockbridge limestone, 467, 491, 528, 530 Stomapod, 783 Stomatopora arachnoidea, 514 Stone age, 1008 Stone coal, 661 ; rivers, 209 ; state, 264 Stones on sea bottom, 144 Stonesfield slate, 411, 775, 777, 787, 788, 789, 790 Stony Creek, Conn., 949 Stormberg beds, 699, 770 Strain, level of no. See Zero-strain Strangeria, 596 Straparollus, 495, 515, 707; Clay- tonensis, 501 ; lens, 647 ; perno- dosus, 690 ; pristiniformis, 501 ; similis, 647 ; Spergensis, 647 ; subrugosus, 690 Strata, stratification, 91* Straticulate, 92 Stratified formations, 90-116 (struc- ture and characteristics, 90 ; cal- culating thickness of, 113, 114* ; conformability, unqonformability, 114), 398, 441, 450 Stratigraphical, 91 Stratum, 91 Strephochetus, 502 Stpepsidura ficus, 916 Streptaxis Whitfieldi, 690 Streptelasma, 550, 562; apertum, 513 ; calyculus, 550 ; corniculum, 504, 505*, 513; expansum, 503; profundum, 513 Streptorhyncus crassum, 690 ; crenistria, 625, 626, 700* ; um- braculum, 625, 704 Striae. See Scratches Striarca centenaria, 899*, 917 Stricklandia lens, 520, 567 ; lyrata, 567 Strike, 99*, 100, 101, 105* Stringocephalus Burtini, 595, 601, 625, 626 Stringocephalus beds, 626, 627 ; zone, 595, 601 Strobilospongia, 513 Stromatocerium pustulosum, 514 Stromatopora, 455, 499, 547, 551, 562, 584, 625; concentrica, 547*, 550, 569 ; ponderosa, 590 Stromatoporids7447, 504 Strombodes gracilis, 550 Stromboli, 276, 280 Strombus Aldrichi, 899*, 917 ; Lei- dyi, 917 ; Sautieri, 865 Strontium, 335 Strophalosia, 707 (ends with Per- mian) ; excavata, 707 ; Goldfussi, 707 ; lamellosa, 704 ; productoides, 628 ; truncata, 620 Stropheodonta, 551, 562, 579, 642; arcuata, 602 ; Cayuta, 621 ; de- missa, 591, 602 ; filosa, 567 ; mag- nifica, 579; mucronata, 620; na- crea, 602 ; perplana, 591, 592, 602 ; punctulifera, 592 ; reversa, 602 ; varistriata, 558 Strophodus, 772 (first), 783 Strophomena, 425, 426, 503, 516, 517, 520, 521, 552, 562 ; alternata, 503, 507*, 514, 524 ; arenacea, 520, 567; compressa, 567; deltoidea, 521 ; depressa, 551, 626 ; expan- sa, 521 ; incrassata, 514 ; pecten, 568 ; planumbona, 426*, 503 ; pli- cifera, 502*, 503; rhomboidalis, 503, 625; rugosa, 568; subplana, 563 ; Woolworthana, 563 Strophomenids, 568 Strophonella euglypha, 567 ; radi- ata, 560* Strophostylus, 562 ; cancellatus, 579 Structural geology, 14, 61-116 (rocks, 61 ; terranes, 89) Struthio, 54 Struthiosaurus, 864 Sturgeon Kiver, 445 Sturgeons, 59, 923 Stylacodon, 768 ; gracilis, 767* Stylina, 760 ; tubulifera, 759* Stylinodon, 905 Styliola, 59* Styliolina, 586, 599 ; fissurella, 592, 598*, 602, 603, 612, 620, 621 Styliolina limestone, 603, 613, 621 Stylodon, 789* Stylolites, 543, 555 Stylonurus, 567, 623 ; excelsior, 615 ; Wrightianus, 615 Sub-, as a prefix, 407, 634 Subapennine marls and sands, 927 Subcarbon period, 632 Subcarboniferous period, 636 Sub-Himalayas, 933, 936 Sub-Oleon conglomerate, 638 Subretopora incepta, 502* Subsidence, 151, 345, 846, 347; Champlain, 981 ; modern, 348, 849, 350, 378, 392; through the Paleozoic, 380, 385 , coral island, the counterpart of continental elevation, 937 ; of the Pacific indicated by coral islands, 149, 350, 392; rate of, in coral islands and in the history of coral reefs, 149*, 150, 151, 202 Subterranean waters, 204-209 Subulites, 514 ; ventricosus, 551 Succinea avara, 966 ; obliqua, 966 Suchoprion aulacodus, 754 Suessonian group, 884, 925 Suillines, 930 Sulcopora fenestrata, 502*, 508 Sulphates, 63, 69 Sulphides, 70 1082 INDEX. Sulphur, 63, 70; in coals, 661, 663, 664 springs, 125 ; in California, 335 ; in New York, 554, 555 Sulphuric acid, 63 ; springs, 125, 555 Sulphurous acid, 63, 124, 125, 324 ; from volcanoes, 278, 293, 294 Sumatra, 22, 88, 40; volcanoes of, 297 Sun, a chief source of geological energy, 117 ; causes of the vary- ing degree and effects of its heat, 253-257 ; its heat as related to the ocean's work, 166, 209, 214; as affecting the temperature and density of water, 214 spots, 11-year cycle of, 177, 255 Sunderland Lake, 533 Superga, molasse of, 926 Superior, Lake, 29, 40, 85, 166, 200, 201*, 206, 483 ; basin, 106, 199 ; copper veins, 272, 823, 338, 339, 465, 466 Superposition, order of, 899, 400 Surcula, 916 Surficial, 1988, 272 Surgent series, 728 Surirella craticula, 164*, 165 Sus, 54, 927 Susquehanna River, 888, 465, 780*, 781, 816 Sussex marble, 864 Swabia, 788 Swallows, 923 Sweden, Archaean in, 456; Cam- brian, 482, 484, 518 ; Lower Silu- rian, 518, 519, 520, 521; Upper Silurian, 563, 564, 565, 568, 569, 573; Triassic, 769; Cretaceous, 888 Switzerland, Cretaceous in, 857, 859 ; Jurassic, 783 ; Tertiary, 920, 925, 926 Sydney sandstone, Australia, 221 Syenite, 85 ; granite, 85 Syenyte, 85 Syenytic gneiss, 85 Synbathocrinus, 602 Synclines, 102*, 103*, 104, 105* Synclinorium, 380, 729, 731 Syncoryne, 429*, 431 Synedra ulna, 164*, 165; vitrea, 699 Syornis, 1014 Syria, Cretaceous in, 857, 859 Syringodendron, 699 Syringopora, 551, 552, 567, 585, 704, 711; bifurcata, 567, 568; Hisin- geri, 591, 592 ; Maclurii, 584*, 590, 592; multattenuata, 690; multi- caulis, 550 ; retiformis, 550 Syringostroma columnare, 590 ; densum, 590 System of formations, 406; of Mountain Ranges, 389; of the Rhine, De Beaumont's, 784 Systemodon, 903, 918; tapirinus, Tabellaria, 168, 164* Table mountain or mesa, 185, 186*, Table Mountain, S. Africa, 699 Tachylyte, 87 Tacoma, Mt., 240 (glacier), 296 (height), 945 Taconian, 446 Taconic limestone belts, 528-531 Range, 24; making of, 386, 527- 532; Cambrian of, 467, 483; Lower Silurian of, 490, 495, 517 ; metamorphism in, 309, 325 Tamia solium, 437 Taeniaster spinosus, 505*, 514 Taeniophyllum, 633 Tseniopteris, 689, 698, 704, 750, 756 ; latior, 756; Lescuriana, 705; linnaeifolia, 749* ; magnifolia, 756 ; multinervis, 705; Newberryana, 705 ; vittata, 705 Tahiti, thickness of coral reef, 150 ; denudation of, 180* ; waterfalls at, 185; tide at, 212; lava streams thicker toward the. interior, 290 Tahitian Islands, map of, 36* Tainoceras cavatum, 691 Talc, 65, 67, 68, 79, 89, 318, 320, 453 Talcahuano, elevation at, 349 Talchir group, 698, 699 Talcose schist, 89 ; slate, 84, 89 Talpa, 927 Tampa limestone, 891 Tancredia, 759, 760 ; Americana, 855 ; extensa, 760 ; Warreniana, 758* Tanganyika (Lake), 38 Tanna Island, 296 Tantalum, 449 Tape-worm, 437 Tapes, 916 Tapir, 54, 902, 981, 1002 Tapiravus, 919 Tapirus, 928; Americanus, 1001; Arvernensis, 927 ; Haysii, 1001 ; Indicus, 905* ; priscus, 927 Tar, mineral, 712 Tarannon shales, 563 Tarawan Islands. See Gilbert Tarawera eruption, 291, 305, 374 Tarn (Mt.), 858 Tasmania, 21, 415, 628, 937, 948 (fiords) Taunusian, 626 Taxinese, 596, 673 Taxites, 777, 840, 921 ; Olriki, 921 Taxocrinus, 602 ; elegans, 505*, 514 Taxodium, 921, 922, 989 ; cuneatum, 838; distichum, 921; distichum Miocenum, 839 Taylor marls, 855 Tchad Lake, 34 Tecali, Mex., limestone, 138 Technocrinus, 577 Teeth, composition of, 72, 78 Tejon beds or group, 830, 831, 884, 885, 888, 889, 916 Teleoceras, 919 Teleodus, 918 Teleosaurs, 787 Teleosaurus, 790 ; Chapmanni, 790 Teleosts, 418, 869; Cretaceous, 812,843 Telephus, 521 Telerpeton Elginense, 772*, 778 Tellina, 916, 917; biplicata, 917; Groenlandica, 984 ; linifera, 916 Tellinomya, 516; alta, 514, 516; Angela, 500 ; machaeriformis, 550 ; nasuta, 507* ; nucleiformis, 558 Tellurium, 381 Telmatherium, 918 Temiscaming Lake, 445 Temiscouata Lake, 533, 559 Temnochilus, 675 ; conchiferum r 690; crassum, 675, 676*, 690; depressum, 690 ; Forbesanum, 690 ; latum, 690 Temnocyon, 911, 918 Temperature, 52, 727, 877 (change', exterminating life); in Archaean time, 440, 441, 442; in mines, 257 ; of the ocean, 46. See also- Climate Temple of Jupiter Serapis, changes of level, 348, 349* Teneriffe, crater of, 277, 291 Tennessee, mean height of, 28 j marble, 494, 524 River, 540 Tentaculite limestone, 535, 552, 556^ 557, 558, 559 Tentaculites, 556, 560 Tentaculites, 516, 562, 568, 586, 599, 626; attenuatus, 592; bellulus, 592 ; distans, 562 ; elongatus, 560, 579 ; gracilistriatus, 592, 620, 621 ; gyracanthus, 556*, 557 ; incurvus, 514; ornatus, 567, 568, 569; Os- wegoensis, 514, 516; Richmond- ensis, 514; scalariformis, 590; scalaris, 625 ; spiculus, 620 ; Ster- lingensis, 514; tenuistriatus, 516 Tephryte, 87 Terebellum fusiforme, 926; sopita, 926 Terebra, 916 ; Houstonia, 916 ; sim- plex, 917 Terebratula, 72 (analysis), 425, 426*, 756, 834, 856; augusta,. 757; biplicata, 791, 865; bovi- dens, 690 ; Choctawensis, 837 ; digona, 779*; diphya, 779*, 791, 793 ; diphyoides, 791 ; elongata, 707; fimbria, 790^ fusiformis,. 704; gracilis, 866; Harlani, 378 r 840*, 854; hastata, 700*; im- pressa, 425*; Liardensis, 758;. perovalis, 790; plicata, 840*, 854; sella, 791 ; semisimplex, 757 ; Sul- livanti, 601 ; vitrea, 426* ; Waco- ensis, 837 Terebratula family, 585*, 779 Terebratulids, 922 Terebratulina Atlantica, 854 ; caput- serpentis, 426*; gracilis, 866; Guadalupae, 855 Teredina personata, 925 Teredo, 158, 425 Termites, 158 Terrace formation, 992 Terrace period, 941 Terraces of rivers, lakes, and sea- shores, 193, 194*, 228, 943, 947, 981-994; height due mostly to height x of flood, 194. See also Flood-grounds ; Shore platforms INDEX. 1083 Terraces, of Champlain period, 981, 986, 986, 991* Terrane, 90 Terranes, 61, 89-116; stratified, 90; unstratified, 116 Terrestrial life rarely fossilized, 141, 525 Terrigenous, 144 Terror, Mt., height of, 296 Tertiary era, 188, 202, 339, 347, 350, 364-366, 380, 381, 392, 407, 408, 409*, 411, 822, 828, 829, 831, 857, 879 ; subdivisions, 880 ; N. Amer- ica, 880 ; foreign, 919 ; general observations, 928; Tertiary ele- vation continued into Glacial period, 946. See also Miocene; Pliocene eruptions, 876 ; in western Amer- ica, 340^ igneous outflows in the Deccan, 299 fresh-water lakes of N. America, 202, 882 mountain-making, foreign exam- ples of, 367-369, 769, 812; oro- genic and epeirogenic move- ments, 932-939 ; orographic move- ments along the Pacific mountain border, 364-366 Teschenyte, 88 Testudinates, 767, 901* Testudo, 901; Atlas, 923; bron- tops, 901*, 902 ; Stricklandi, 787, 790 Tetrabranchs, 424, 425*, 781, 869 (pass their climax) Tetracoralla, 431 , 718 Tetractinellids, 431 , 432* Tetradecapods, 420*, 421, 423, 438, 439, 525, 574, 707, 720, 721, 724, 725 Tetradium, 501, 505; cellulosum, 515; columnare, 514; fibratum, 511*, 515 Tetragraptus bryonoides, 500 ; fru- ticosus, 500 Tetrahedrite, 335 Tetrapterus priscus, 925 Texas, mean height of, 23 ; Archaean in, 444, 446, 447 ; Cambrian, 464, 466, 469, 477, 484; Upper Silu- rian, 537; Devonian, 575, 580; Subcarboniferous, 637 ; Carbonif- erous, 648, 690, 693 ; Permian, 660, 685, 687, 688; Triassic, 660, 746; Cretaceous, 817, 824, 854; disturbances in, 868; Ter- tiary, 884, 885, 888 ; Quaternary, 378 Textularia, 855 ; globulosa, 432* Thalassic, 535 Thalassophyllum clathrus, 582 Thames River, Conn., 461, 949 Thames River, Eng., 191 Thamnastrsea, 777, 778 (number of British); concinna, 790; gre- garia, 790 Thanet sands, 920, 925 Thanetian group, 925 Theca, 481, 514, 521, 707 ; parvius- cula, 514, 516 Thecidium family, 779 Thecodontosaurus, 773 ; gibbidens, 754 Thecodonts, 754 Thecosmilia, 777, 778 (number of British) ; annulata, 790 Thelodus parvidens, 566*, 567 Thelyphonus, 723 Thenaropus heterodactylus, 692 Thermal waters, 258, 305-309, 334, 335 Theromora, 688 Theromores, 707 Thian-Shan Mts., 32 Thick-bedded structure, 92 Thielson, Mt., 266 Thimble Islands, degradation at, 260 ; pot-holes of, 949 Thinohyus, 911, 918 Thinolite, 133* Thoracosaurus, 848 Thorium, 449 Thracia Conradi, 983 ; curta, 984 ; depressa, 791 Thrissops, 417* Thrust-planes, 534 Thuia, 840 Thuringia, Permian in, 706 Thuyites, 777 Thysanura, 419, 702 Thysetes verrucosus, 567 Tiaropsis, 429* Tibet, 26, 32; Silurian of, 868; Triassic in, 770; Jurassic, 791; folded Nummulitic beds of, 521, 920 ; Mammals of, 936 Tiburtine, 79 Ticholeptus beds, 886, 894, 895 Tick, 420 Tidal wave and currents, 43, 210 ; on Lake Michigan, 202 Tide and currents in the Cambrian, 484 ; Devonian, 629, 630 Tierra del Fuego. See Fuegia Tile clay, 665 Tile-fish, 56 Tilestones, 563, 566 Tilibiche, coral limestone at, 347 Till, 81, 251 Tillodonts, 903, 904, 917, 918 Tillotherium, 904, 918; fodiens, 904*, 905 ; latidens, 904*, 905 Timber Belt beds, 888 Time, geological, subdivisions of, 404 ; ratios and length, 1023 Timpahute Range, 366*, 469 Tin, 83, 88, 336, 343 Tinacoro Island, 296 Tinoceras, 907, 918; anceps, 907; grandis, 907 ; ingens, 906*, 907 Tinodon bellus, 767* Tionesta basin, 947 Tipula Carolina?, 900* Tipulidse, 900 Tirolanus Cassianus, 773 Tisiphonia, 432* Titanic acid, 86 ; iron, 70, 449, 450 Titanichthys, 618 ; Clarki, 619 Titanite, 67 Titanium, 70, 455 Titanophasma Fayoli, 701, 702* Titanosaurus, 867 Titanotheres, 907, 908, 91)9, 918 Titanotherium anceps, 907 ; gigan- teum, 908*, 909 Titanotherium beds, 886, 893, 908, 910, 918 Tithonian group, 779, 791 Titicaca, Lake, 26, 347, 627 Toarcian group, 775 ; (Upper), 790 Tredi-Windgaellen group of moun- tains, 367 Tofua Island, 296 Toluca, Mex., 265 Tom, Mt., 802; Ridge, 801*, 803, 804, 805, 806, 807 Tombigbee River, 885, 889 ; sands, 815, 823, 854 Tomitherium, 918 Tonga Islands, 37, 350, 374 Tongrian group, 884, 926 Tongue River, 266 Tonto group of Gilbert, 447, 469 Topaz, 63, 66*, 338 Topazolites, 312 Torbanite, 662 Tornoceras mithrax, 591 Torosaurus, 847 ; gladius, 846* Toroweap fault, 362, 363* Torre del Greco, 294 Torres Strait, 937 Torrid zone, 46 Torridonian group, 457 Torsion, 105, 106*, 107, 371 ; effects of, in ice, 371, 372*; in strata, 105, 106*, 371 as an explanation of the zigzag arrangement of continents, 394, 395 Tortoises, 787 Tortone blue marls, 926 Tortonian group, 884, 926 Totoket Ridge, 801*, 802, 803, 806 Toucan, 54 Touraine, 926 Tourmaline, 63, 66*, 82, 88, 160, 312, 320; crystals displaced by quartz, 138* ; rocks, 82, 83 Tourmalyte, 88 Toxaster Campicheii, 865; compla- natus, 865 Toxoceras bituberculatum, 862*, 865- Toxodon, 927 Toyabe Range, 365 Tracheates, 419 Trachelomonas laevis, 163, 164* Trachodon mirabilis, 846 Trachyceras, 756; aonoides, 774; Archelaus, 774 ; balatonicum, 774 ; binodosum, 774 ; Canadense, 758 ; Curionii, 774 ; Reitzi, 774 ; trino- dosum, 774 ; Whitneyi, 757* Trachyte, 80, 84, 86 ; difference in density of glass and stone states. of, 265 ; relation to granite, 814 Tracks. See Footprints Trade winds, 50, 51, 159, 166 Trails. See Footprints Transition rocks, 408 Translation-waves, 213 Trans-Pecos region, 824, 874 Transportation by currents of water, 169, 189 by glaciers, 247 ; by waves, 222 of, and by, plants and animals, 15ft 1084 INDEX. Transylvania, 85 Trap, 86 in Connecticut valley Triassic, 800 Trapa natans, ash of, 75 Traverse (Lake), 947 Travertine, 79, 131, 132*, 133 Tree-ferns, 53, 669* Trees, protection by, 155 Tremadictyon reticulatum, 777* Tremadoc slates, 481, 517 Tremataster disparilis, 646 Trematis, 514 Trematodiscus Konincki, 700* Trematopora, 551 Trematosaurus, 773 Trematospira, 562 ; multistriata, 551, 579 Tremolite, 67, 79, 819, 531 Tremolitic limestone, 79 Trends, systems of, 35 Trenton, 490 Treodopsis appressa, 967 Triarthrus, 515; Beckii, 422*, 511*, 512*, 516 Triassic period, Trias, 738 ; Ameri- can, 740, 746 ; foreign, 768 Triceratium obtusum, 894* Triceratops prorsus, 846* ; serratus, 846* Trichiulus villosus, 691 Trichomanites, 622 Triconodon mordax, 789* Tridymite, 64, 84, 318, 323, 338 Trigonarca pulchra, 915; Sioux- ensis, 855 Trigonia, 59, 707, 759 (first Ameri- can), 760, 780 (number of Jurassic), 860; aliformis, 867; carinata, 865; caudata, 865; clavellata, 780*, 790; Conradi, 758*; costata, 790, 791; Eufau- lensis, 854 ; gibbosa, 791 ; incurva, 791; limbata, 866, 867; longa, 867; Mortoni, 854; navis, 792; paucicosta, 790; scabricula, 865; Smeei, 791 ; ventricosa, 791 Trigonia family, 770 Trigonocaris Lebescontei, 521 Trigonocarpus, 622, 673*, 689 ; ornatus, 673*, 689 ; tricuspidatus, 673*, 689 Trigonoceratidae, 675 Triisodon, 917 Trilobites, 59, 420*, 421* ; Cambrian, 469, 480, 482, 483, 488 ; legs of, 422*, 512* ; young of, 512*, 562* Triloculina Josephina, 432* Trinidad, Col., 313 Trinidad, W. I., 22, 891 Trinity epoch or group, 815, 817, 832, 834, 836, 887; sands, 817, 819 Trinucleus, 422, 520, 521 ; concen- tricus, 508*, 509, 512, 515, 516, 517, 520, 567, 569 Triolites Cassianus, 773 Trionyx, 850, 926 Triopus, 521 Triphylite, 321 Triplesia primordialis, 478* Triplopus, 918 Tripolyte, 81 Tripriodon, 852 ; caperatus, 853* ; ccelatus, 853* Trisetum, 240; subspicatum, 945 Trispondylus, 917, 918 Tristan d'Acunha, 297 Tritonium, 916 Tritylodon, 773, 789 Trochoceras, 515, 549, 568, 586 (last), 591 ; boreale, 552 ; clio, 591 ; cos- tatum, 551 ; Desplainense, 551 ; eugenium, 591 ; Halli, 515 ; no- turn, 551 ; pandum, 591 Trocholites, 506, 520; Ammonius, 506, 508*, 511, 515, 516 ; undatus, 506, 508*, 514 Trochonema, 514, 516, 520, 521, 598 Trochosmilia striata, 916 Trochus, 525, 780 ; Texanus, 836 Trogons, 923 Troodon, 856 Troostocrinus, 646 ; subcylindricus, 547*, 550 Trophon clathratum, 984, 995 Tropidocaris bicarinata, 621 Tropidoleptus, 627 ; carinatus, 598*, 601 Tropites, 756, 757 ; subbuUatus, 774 Truckee Miocene, 895 Tsien-Tang, the eager of, 212, 215 Tuba acutissima, 917 Tubicola, 423 Tucubit Mts., 581 Tuedian group, 695 Tufa, volcanic, 80 ; cones of, 270, 271*, 276* Tufa, calcareous, 131, 132* Tulip Tree, 812, 837, 879 Tully limestone, 576, 593, 594, 599, 601, 603, 605 Tunicates. See Ascidians Tunneling by animals, 158 Turbinella regina, 917; Wilsoni, 916 Turbinolia Texana, 887 Turbo, 707, 780; Shumardi, 591; solitarius, 774 Turf, protection by, 155 Turkey, 34 Turonian group, 815, 858, 859, 866 Turricula Millingtoni, 916; polita, 916 Turrilepas, 567, 579, 602 ; Canaden- sis, 513* ; Devonicus, 600* Turrilite, 861 Turrilites, 771, 861; Brazoensis, 837 ; catenatus, 862*, 865 ; costa- tus, 866 ; helicinus, 855 ; pauper, 854 ; tuberculatus, 866 Turritella, 824, 916, 922 ; Alabami- ensis, 915; alveata, 916; areni- cola, 916 ; cselatura, 916 ; carinata, 897*, 916 ; Chipolana, 917 ; com- pacta, 854; erosa, 984; indenta var. mixta, 917 ; Mississippiensis, 916; multisulcata, 926; nasuta, 897*, 916; perdita, 916; plebia, 378 ; prsecincta, 915 ; pumila, 854 ; reticulata, 984 ; subgrundifera, 899*, 917; Tampse, 898*, 916; vertebroides, 854 Turtles, 415, 847; Triassic, 772* 773, 797 ; Jurassic, 760, 766*, 767,' 768, 797; Cretaceous, 826, 849, 856, 867 ; Tertiary, 202, 901*, 902, 923, 927 Tuscaloosa group, 815, 816, 819 } Tylosaurus micromus, 849* Typhis, 916; acuticosta, 917; cur- virostratus, 916 ; pungens, 926 Typothorax coccinarum, 758 Tyrol, dolomyte of, 134 Tysonia Marylandica, 831 Uinta Eocene lake basin, 360*, 881*, 882, 886, 893 Mts., 109, 360*, 365 Uintatherium, 907, 918; Leidya- mim, 907 ; robustum, 907 Uitenhage series, 873 Ullmannia, 693, 704 Ulodendron, 699 ; majus, 689 ; punc- tatum, 689 Umbone, 424 Umbral series, 684, 728 Unaka Mts., 85 Unakyte, 85 Unartok series, 921 Unconformability, 114, 115*, 116 Unconformity, 115* Under-clay, 639, 653, 708 Ungulates, 902, and beyond Ungulina, 621 Unio, 612, 821, 829, 837; Danse, 856 ; Deweyi, 856 ; ebenus, 966 ; Liassinus, 760 ; ligamentinus, 966 ; rectus, 966 ; Valdensis, 861* Unio family, 946, 950 Uniontown coal-bed, 651, 656 United States, mean height of, 23 ; geological map of, 412* ; heights of the Cretaceous beds of the Kocky Mountains, 933 Untercarbon, 682 Unterer Wieder Schiefer, 569 Upernavik, 244 Uphantaenia Chemungensis, 611 Upper Pentamerus. See Pentame- rus Silurian, 535 Uralichas Kibeiroi, 521 Uralite, 317 Uralitization, 317 Uraninite, 321 Uranium minerals, 821 Uranoplosus, 836 Urformation, 440 (Archaean syn- onymy) Urgebirge, 440 (Archaean synony- my) Urgneiss, 408 Urgneissformation, 440 (Archaean synonymy) Urgonian, 867*, 859, 865 Urocordylus Wandesfordii, 704 Urosalpinx trossulus, 917 Urosalpynx cinerea, 994 Urosthenes australis, 698 Urosthenic, 439, 717, 726, 796, 931 Ursa stage of Heer, 704 Ursus amplidens, 1000; Arctos, 950, 1004, 1006 ; Arvernensis, 927 ; INDEX. 1085 ferox, 1006 ; pristinus, 1001 ; spe- ISEUS, 1004*, 1009 Urus, 1013 Utah, mean height of, 23; high plateaus of, 187, 386 ; Henry Mts. in, 301 ; ore beds of, 338, 339*, 340 ; map of, 360* , Archaean in, 449 ; Cambrian, 469, 473, 476; Lower Silurian, 469, 495; Trenton, 495; Carbon- iferous, 301, 658, 674, 690; Per- mian, 660 ; Triassic, 746 ; Jura- Trias, 749; Jurassic, 747, 760; Cretaceous, 302, 339*, 340, 825 (coal), 826, 829, 856 ; post-Meso- zoic, 876 ; Tertiary, 302, 365, 366, 882, 886, 893, 901, 934 Ute limestone, 494 Utica and Hudson epochs, 489, 492 Val d'Arno, 927 Valdivia, 51 Valenginian, 859, 865 Valley drift, 946 Valleys, excavation of, 180, 182 ; filled, not excavated by the ocean, 228 Vallonia pulchella, 966 Valparaiso, banded and other veins, 329*, 332* ; earthquake in 1822, 849 Vanadate, 340 Vancouver Island, 23, 747; Creta- ceous of, 818 ; coal of, 825 ; coal- plants of, 837, 840, 872 Eange, 25, 812, 892 Vanuxemia Montrealensis, 503 Varenna marble, 774 Vasum horridum, 917; subcapitel- lum, 916 Vavau Island, 39, 350 (elevation) Vegetable kingdom, 9, 413, 414, 434-437 Vegetation, protection by, 155 Vein-structure of glaciers, 243 Veins, 327; of Archaean rocks, 449 Veinstone, 331 Veleda lintea, 854 Venericardia borealis, 917 ; plani- costa, 897* Venezuela, 31, 857 (Cretaceous) Veniella Conradi, 854 ; trapezoidea, 854 Ventriculites, 482*, 860 Venus, density of, 16 ; oblique lines on surface of, 395 Venus, 425, 916 ; cortinarea, 917 ; mercenaria, 994 ; rugatina, 900*, 917 Venus's Flower-basket, 432 Verd -antique marble, 68, 77, 79, 89 Vergent series, 728 Vermes, 423 Vermiceras Crossmani, 760 Vermicular limerock, 555; sand- stone and shales, 637 Vermilion Cliffs, 187, 747 group, 886 Pass, 469 schists, 44fl Vermont, 23 (height), 325, 496 ; eo- lian limestone, 517 ; faults, 527, 528* ; fossils, 309, 310, 887, 896 ; marbles, 524, 528 Vertebraria, 698 Vertebrates, 141, 404, 414, 415-418, 424 ; relation of, to Invertebrates, 418; Merosthenic, era of, 796; Urosthenic, era of, 796 , Lower Silurian, 496, 509, 525 ; Paleozoic, 725-726 Vesicular rocks, 78, 298 Vespertine series, 634, 728 Vesperugo, 918 Vesulian group, 790 Vesuvius (Mt.), 85, 266*, 276, 280 Viburnum Goldianum, 839 Vicksburg epoch (beds), 880, 884, 889, 890, 896, 898*, 916 Victoria, Lake, 200 Victoria (province), 698, 699 Vicuna, 54 Vienna, Miocene of, 922, 939 Viesch glacier, 237 View of the aa lava-stream, 287* View of alluvial cones, Indus Basin, 195* View of an atoll, 145* View of Beehive Geyser in action, 308* View of blocks on the shore-plat- form of the Paumotus, 222* View (ideal) of Carboniferous vege- tation, 666* View of cliffs, Port Jackson, N.S. W., 221* View of Colorado Canon, 188* View of columnar basalt, Orange, N.J.,262* View of drop-made and of rain- made columns, 178* View in Elk Mts., showing up- turned strata, 106*, 364* View of Geyserite Terraces, N. Zeal., 305* View of the Gorner Glacier, 237* View of Gothic Mt., Col., 275* View of a high island with barrier and fringing reefs, 148* View of jointed rocks, Cayuga Lake, 112* View of Juke's Butte, 301* View of Kiama basaltic columns. 261*, 262* ViewofKilauea, 270* View of loess formation on the Hoang Ho, 196* View of Mammoth Hot Springs, 132* View of Marble Canon, 187* View of the southwest end of Mok- katam, 160* View from Monument Park, illus- trating erosion, 186* View of Mount Shasta, 267* View of Nanawale cinder-cones, 285* View of Oahu tufa-cones,~271* View of Obsidian Cliff, Yellowstone Park, 264* View of " The Old Hat," New Zea- land, 221* View of Phonolyte Peak, Fernando de Noronha, 263* View of plicated clayey layer, 209* View on Boche-Moutonnee Creek, 250* View of rocks detached by wave- action, Mount Desert, 219*, 220* View of rocks disrupted by roots of trees, 157* View of sandstone veins, Oregon, 844* View of Temple of Jupiter Serapis, 349* View of terraces on the Connecticut Eiver, 194* View of trap bluff at Greenfield, 805* View of tufa deposits, Lake Mono, 132* View of upturned Cretaceous beds near Abu Eoasch, 161* View of Vesuvius, 266* View of water-and-gas geyser, Pa., 608* View of West Eock, 804* Virgen, Eio. See Virgin Eiver Virgin Eiver, 339, 363 Virginia, 23 (height), 24, 125, 353, 357, 358, 383, 387, 437, 468; iron ore beds, 127, 449; section of rocks, 355 ; upturnings in, 532, 808 Virgloria, Virglorian, 774 Virgulian group, 791 Vise limestone, 696 Viso, Mt., 266 Vitrifiable clay, 81 Vitriol, 70 Vitulina, 627 Viverra, 927 Viviparous Mammals, 415 Viviparus, 856 ; fluviorum, 861* Volcanic action and its causes, 277- 293 ; reached its maximum in later Cretaceous and Tertiary, 326 Volcanic ashes, eolian transporta- tion of, 80 ; deposited over the sea bottom, 136 - belt separating northern and southern continents, 394 bombs, 287*, 2S9 eruptions, earthquakes not essen- tial in, 286 glass, 84, 86, 87, 263, 264*,272- 2S8 mud. See Tufa necks, 290 rocks, 84, 272, 298 vapors, 268, 269, 277-282, 283- 288 (passim); work of spent vapors, 293-295 Volcanoes, distribution of, 295-297 ; number, 297 ; occurrence in lines, 282; of continents mostly on their borders, 295, 392; conti- nental distinguished from oceanic, 379 , carbonic acid from, 128, 278 , extinction of, 290-291 ; interior of, before and after extinction, 290, 291 Volga, 88 1086 INDEX. Volgian, 760, 790 Volsella scalpra, 760 Voltzia, T50, 774 ; heterophylla, 698, 770*, 773 Voluntomorpha Eufaulensis, 854 Voluta, 922 ; ambigua, 926 ; athleta, 926 ; Newcombiana, 915 ; nodosa, 925; Showalteri, 915; Wether- ellii, 925 Yolutilithes Haleanus, 916 ; limop- sis, 896*, 915 ; rugatus, 896*, 915 Vosges, 310, 626, 734 (upturnings), 738 ; Archaean in, 456 ; Triassic, 768 Vosgian, 738, 769, 773 Vraconnian, 859 Vulcano, 276 Waagenoceras, 686 Wabash River, 947 Wachita Mts. See Ouachita Wacke, 80, 408 Waders, 141 (easily fossilized), 852, 902 Wadesboro Triassic area, 741 Walderthon, 865 Wairoa series, 770 Wakes Island, 38 Walchia, 693, 699, 704, 750 ; pini- formis, 699, 704, 705* Waldheimia, 59 ; compacta, 690 ; digona, 790 ; humeralis, 791 Wales, 173, 191, 370, 463, 464 ; erup- tions in, 518 ; upturnings in, 534, 783 ; geological map of, 694* , Archaean in, 456, 457 ; Cambrian, 457, 480, 481; Lower Silurian, 517, 518, 520; Upper Silurian, 563, 564, 568, 574 ; Devonian, 622, 625 ; Subcarboniferous, 695 ; Car- boniferous, 322, 662, 693, 694*, 695, 696, 734 ; Permian, 734 ; Tri- assic, 768 Walker's Lake, 757 Wallala beds, 830, 840 Walnut clays, 817 ; sands, 886 Warrior coal-fields, 648, 657 Warsaw group, 634, 637, 638 Wasatch Eocene basin or lake, 360*, 361, 865, 881*, 882, 893 limestone, 580, 581, 659 Wasatch Eange, 24, 25, 340, 359, 360* (map), 874 , Archaean in, 444, 447; Cambrian, 469 ; Trenton, 494 ; Upper Silu- rian, 541 ; Devonian, 360*, 361, 362, 580, 581; Carboniferous, 360*, 361, 362; Mesozoic, 380; Triassic, 747 ; Jurassic, 747, 760 ; Cretaceous, 360*, 361 ; post-Mes- ozoic, 874, 875; Tertiary, 365, 366, 934 Washakie group or basin, 886, 893 Washburn, Mt., 276, 296 (height) Washington, Mt., Mass., 104, 105*, 528, 530 Washington, state, mean height of, 23 ; glaciers of, 240 ; volcanoes of, 296, 937 ; coal of, 831 ; Tertiary in, 885, 892 Washita epoch or group, 815, 817, 819, 886 ; limestone, 817, 887 Water, arrangement of seas, 16; composition of, 71 ; character- istics of, 170-171; amount ab- sorbed within the earth, 209; freezing and frozen : glaciers and icebergs, 118, 171, 230-253 as a chemical agent, 118; as a solvent, 118, 119, 121, 122 ; chem- ical absorption of, 128; carbonic acid in rain, river, and sea, 128 Water-lime group, 410, 535, 552, 553, 554, 555, 556, 558, 559, 570, 571, 606; American species occurring elsewhere, 569 Water-line of coasts, 346 Water-sculpture of mountains, 185, 186* Water-spout, 163 Waterfalls, 174, 184, 185 ; in glacier Crevasses, 250 Waterglass, 135 Wave-marks, 94, 538 Waverly group, 604, 638 Waves, action and force of, 210, 212 ; height of, 213, 216 ; limit of de- nudation by, 219, 221. See also Tidal wave Waynesburg coal-beds, 651, 657, 663, 677 Weald axis, 936 Wealden epoch, 858 Weasel, 924 Weathering, 128, 136 Weber, 360*, 361, 362 conglomerate, 659 ; quartzyte, 659 Weevils, 771 Weissliegende, 697 Wellenkalk, 769, 773 Wellington Strait, 544, 552 Wells. See Artesian ; Mineral oil Welwitschia, 435, 674; mirabilis, 435* Wengen shales, 774 Wenlock Edge, Scotland, 534 group, 463, 519, 563, 564, 565, 566, 567, 568 limestone, 563 ; shale, 563 Werfen (Werfenian) beds, 769, 773 Wernerite, 65 West Humboldt. See Humboldt West India basin, 857 West Indies, 19, 21, 22, 40 (trends), 145 (coral reefs), 153, 296 (volca- noes), 428, 429, 431, 578, 891 (Mio- cene) West Peak, Col., 266 West River, 227 West Rock dike and Eidge, 299*, 302*, 303, 801*, 802, 803, 804* (view), 805, 806, 808 West Virginia, height of, 23 ; min- eral oil in, 607, 608 Western border region. See Pacific border Western Continental Interior (sea) of N. America, 575, 580, 635, 739, 872 ; Triassic and Jurassic in, 746-749, 756-768 ; Cretaceous, 818*, 814, 867, 873, 880 ; Tertiary, 880 Western Isles of Scotland, 288 Westphalia, 627 ; coal-beds, 696 Wetterstein, 774 Whale-bone Whales, 912*, 925 Whales, 56, 144, 415, 902, 908, 912, 927 (toothed), 931 ; ear-bones of, dredged, 144 Whetstone, 80 Whip-snake, 682 White ants, 159 White Bluff bed, 889 White Cliff group, 747 White Fish River, 445 White Island, eruption, 374 White Lias, 774, 790 White Mts., N. H., landslide in, 208 ; incipient glacier in, 234; Arctic plants of, 945, 946 White Pine district, 495 White River, 894, 901 White River beds, 884, 886, 893 White Sea, 521, 768 Whitfieldella didyma, 567; nitida, 548*, 551 ; oblata, 549 Whitney, Mt., 810 Whittleseya, 689 ; elegans, 674 Whortleberry, 921 Wianamatta shale, 699 Wichita, 660 Wight, Isle of, 920, 926 Wild Boar, 54, 902, 927 Willamette River, 30 Willoughby, Mt., 945 Willow, 837, 859, 879 Willow Creek beds, 830 Willow River limestone, 493 Wind, 89 ; denudation by, 159 Wind-drift coral rocks, 151 ; struc- ture, 93*, 162 Wind-made waves and currents, 166, 212, 216 Wind River basin and group, 884, 886, 893, 918; Mts., 240 (glaciers), 639, 748, 945 Windsor series, 639 Windward Islands, 44 Winnipeg Lake, 29, 199, 200, 515, 524, 552; climate of, 944; dis- charge into the Mississippi, 947 ; . in the Champlain period, 985 Winnipegosis (Lake), 594 Winooski limestone, 467, 472 Wisconsin, 23 (height), 536, 944 (rainfall) ; lead mines, 842, 522 Wodnika striatula, 707 Wolf, 924, 927 Wolf Creek conglomerate, 605 Wood brought down by rivers, 191 ; carbonized, 892; composition of, 74, 123, 713; decomposition of, 123, 124, 613; silicified, 125, 135, 143, 280, 300, 892 (see also Petri- factions) Woodchuck, 915 Woodocrinus elegans, 640*, 646 Woodpecker, 902 Wood 1 s Bluff beds, 888 Woodville sandstone, 657 Woodwardia latiloba, 839 Woolhope beds, 563 Woolwich beds, 925 Worcester, Mass., 453, 461, 633, 635, 646, 658, 714, 732 INDEX. 1087 Worm-burrows, Archaean, 446; Cambrian, 464, 470, 477*, 480; Hamilton, 593 Worms, Sea, 59 ; trails of, 95 ; work of common earth-, 156 ; charac- teristics of, 418, 419, 420*, 423, 437; Cambrian, 469, 474, 477*, 487 Wrangel Bay, 747 Wright, Mt., 238 Writing slate. See Koofing slate Wyoming, height of, 23, 29, 85, 338, 360, 365, 808 ; Archaean, 449 ; Cambrian, 466, 476 ; Subcfirbonif- erous, 639 ; Coal-measures, 662 ; Triassic, 746, 747 ; Jurassic, 748, 760, 761, 763, 767, 768; Creta- ceous, 825 (coal), 826, 828 (coal). 845, 847, 848, 849, 876 ; Tertiary, 882, 886, 893, 894, 906, 907 ; Gla- cial, 945 Xanthidia, 582, 583*, 859 Xenoneura antiquorum, 600* Xiphodon, 924, 926 ; gracilis, 924*, 926 Xylobius, 701 ; fractus, 691 ; Ma- zonus, 691 ; similis, 691 ; sigilla- rise, 678*, 682, 691, 703 Xystrodus, 692 Yablonoi Mts., 32 Yang-tse-Kiang, 30, 198 Yellow ocher, 71 , 126 Yellow Eiver, China. See Hoang Ho Yellow Sea, 198 Yellowstone Lake, 200, 306 Yellowstone National Park, 29, 30 ; geysirite, 82, 152 ; Obsidian cliff, 84, 263; Death Gulch in, 128; calcareous deposits or travertine, 79, 131, 152 ; volcanic peaks of, 296; lithophyses in, 337; time of eruptions, 876, 937 ; geyser region, hot springs, etc., 135, 305, 300* ; siliceous Algae, 152 Yellowstone Elver, 29, 266, 830, 937 Yenisei Eiver, 30 Yews, 53, 435, 596, 639, 666, 673, 685, 718, 735 Yoldia, 760, 917 ; arctica, 984, 995, 997; Claibornensis, 915; eborea, 915; glacialis, 983, 984; limatula, 917, 984 ; sapotilla, 917 Yoredale group, 695 Yorktown epoch, 884, 891, 899* Yosemite domes, origin of, 260 Yosemite valley, 810 Ypresian group, 925 Yttrium, 449 Yucatan, 40, 44 Yukon district, 818, 868 Zambesi Eiver, 30, 33 Zamia, 434, 750 Zamites acutipennis, 833, 834 ; aper- tus, 834 ; borealis, 834 ; Montana, 833, 834 ; occidentals, 756 Zanclean beds, 927 Zanskar district, 456, 791 Zanzibar, 83 Zaphrentis, 515, 516, 551, 552, 562, 579, 591, 597, 611, 640, 674, 700, 718 ; bilateralis, 545*, 550 ; Cana- densis, 515 ; Edwardsi, 590 ; gi- gantea, 584*, 590, 591 ; Halli, 601 ; minas, 646; prolifica, 590; Rafi- nesquii, 584*, 590 ; simplex, 601 ; spinulosa, 646 Zeacrinus, 646, 690 Zebra, 54 Zechstein, 697, 707 Zeolites, 68, 78, 312 ; at Plombieres, 323 ; origin of, 336 Zermatt, glacier of, 237* Zero-strain, depth of, 3S4, 385, 387 Zeuglodon, 822, 908, 912, 923, 931 ; cetoides, 908* Zinc ores, 70, 340, 342, 449, 542 Ziphias, 144 Zircon, 67 , 85, 455 ; syenyte, 85, 447 Zirconia, 67 Zirconitic granite, 83 Zirconium, 449 Zizyphus fibrillosus, 839 Zoantharia, 431 Zoisite, 66, 88, 318 Zones, 407 Zygospira modesta, 514, 516 CORRIGENDA AND ADDENDA. Page 93, Fig. 62 should be inverted. " 237, 3d line from foot, for " Lauterarr," read " Lauteraar." " 525, 13th line, for " Area," read " Area." " 572, 25th line, for " geanticline," read " geosyncline." " 716, 25th line, after "was," read "much longer than Neopaleozoic ; "" 27th line, for "6:1:2:2," read "7 (or 8):1:2:2;" also add to the paragraph : "The Eopaleozoic, as has been shown (pages 509, 520), continued on after the first appearance of Fishes and Insects, types that were formerly supposed to date from the Devonian." " 988, 9th line, after "1895," add " and F. B. Taylor, Am. Jour. Sc. t 1895." " 1036, add: "The Memoir by E. Dubois on Pithecanthropus erectus is. noticed in the number of the Am. Jour. Sc. for February, 1895." 1088 USE RETURN TO DESK FROM WHICH BORROWED EARTH SCIENCES LIBRARY TEL: 642-2997 This book is due on the last date stamped below, or oo the date'to which renewed. Renewed books are subject to immediate recall. MAR i 1074- LD21-35m-8,'72 (Q4189S10)476 A-32 General Library University of California Berkeley YD I