UNIVERSTTYsfttUFORNIA COLLEGE of MINING DEPARTMENTAL LIBRARY BEQUEST OF SAMUELBENEDICTCHRISTY PROFESSOR OF MINING AND METALLURGY 1885-1914 TEXT-BOOK OF GEOLOGY DESIGNED FOE, SCHOOLS AND ACADEMIES. BY JAMES D. DANA, LL.D., AUTHOR OF "A MANUAL OF GEOLOGY," "A SYSTEM OF MINERALOGY," OF REPORTS OF WILKES'S EXPLORING EXPEDITION ON GEOLOGY, ZOOPHYTES, AND CRUSTACEA, "CORALS AND CORAL ISLANDS," ETC. E&ttton. ILLUSTRATED BY 400 WOODCUTS. IVISON, BLAKEMAN", TAYLOR, & CO., NEW YORK AND CHICAGO. Entered, according to Act of Congress, in the year 1863, BY THEODORE BLISS & CO., in the Clerk's Office of the District Court of the United States for the Eastern District of Pennsylvania. Entered according to Act of Congress, in the year 1874, BY IVISON, BLAKEMAN, TAYLOR, & CO., in the Office of the Librarian of Congress, at Washington. UNIVERSITY PRESS : WELCH, BIGELOW, & Co., CAMBRIDGE. PREFACE. IN preparing this abridgment of my Manual of Geology, the arrangement of the larger work has been retained. The science is not made a dry account of rocks and their fossils, but a history of the earth's continents, seas, strata, moun- tains, climates, and living races; and this history is illus- trated, as far as the case admits, by means of American facts, without, however, overlooking those of other continents, and especially of Great Britain and Europe. No glossary of scientific terms has been inserted, because the volume is throughout a glossary, or a book of explana- tions of such terms, and it is only necessary to refer to the Index to find where the explanations are given. The teacher of Geology, and the student who would ex- tend his inquiries beyond his study or recitation-room, is referred to the Manual for fuller explanations of all points that come under discussion in the Text-book, including a more complete survey of the rock-formations of America and other parts of the world, with many sections and details of local geology, a much more copious exhibition of the ancient life of the several epochs and periods and of the principles deduced from the succession of living species on 303417 iv PREFACE. the globe, a more thorough elucidation of the depart- ments of Physiographic and Dynamical Geology, a chap- ter on the Mosaic Cosmogony, a large number of addi- tional woodcut illustrations, with references to authorities, and personal acknowledgments, besides a general chart of the world. This second edition of the Text-book has been changed throughout, so as to make it conform in all respects to the new edition of the Manual. NEW HAVEN, CT., November 2, 1874. TABLE OF CONTENTS. PAGE INTRODUCTION 1 PART I. Physiographic Geology. 1. General Characteristics of the Earth's Features .... 5 2. System in the Earth's Features 8 PART II. Lithological Geology. I. CONSTITUTION OF ROCKS 14 1. General Observations on their Constituents . . . 14 2. Kinds of Rocks 20 II. CONDITION, STRUCTURE, AND ARRANGEMENT OF ROCK-MASSES 27 Stratified Condition . 31 1. Structure 31 2. Positions of Strata 37 3. Order of Arrangement of Strata .... 44 REVIEW OF THE ANIMAL AND VEGETABLE KINGDOMS. 1. Animal Kingdom ......... 48 2. Vegetable Kingdom 60 PART III. Historical Geology. General Observations . . . . . . . . .64 I. ARCHAEAN TIME 73 II. PALEOZOIC TIME . .78 I. AGE OF INVERTEBRATES, OR SILURIAN AGE ... 79 1. Primordial Period 80 2. Canadian and Trenton Periods . . . . . 84 3. Upper Silurian Era 93 vi CONTENTS. II. PALEOZOIC TIME (continued). II. AGE OF FISHES, OK DEVONIAN AGE V .- . . 103 III. CARBONIFEROUS AGE, OR AGE OF COAL PLANTS . . 114 GENERAL OBSERVATIONS ON THE PALEOZOIC * . . 140 DISTURBANCES CLOSING PALEOZOIC TIME ... . 150 III. MESOZOIC TIME . .- . .. * . . . . . 157 REPTILIAN AGE . . . . . . ... 158 1. Triassic and Jurassic Periods . . . . .159 2. Cretaceous Period . ... . . - -..-. .- - 184 GENERAL OBSERVATIONS ON THE MESOZOIC . . . 196 IV. CENOZOIC TIME >. .::.. . . .; ,. i. . 201 I. TERTIARY AGE, OR AGE OF MAMMALS . . . . 202 II. QUATERNARY AGE, OR ERA OF MAN . * , .. . 219 1. Glacial Period . . . . . v . . 220 2. Champlain Period . . ... ...,'... . 225 3. Recent Period . ';.'./."'. . . 229 III. LIFE OF THE QUATERNARY . . ' ! ; .'' . 232 GENERAL OBSERVATIONS ON CENOZOIC TIME .- :_ ; . . 243 V. GENERAL OBSERVATIONS ON GEOLOGICAL HISTORY 245 PART IV. Dynamical Geology. I. LIFE . .".... . . . . . . 264 1. Peat Formations . . . , . . . 265 2. Beds of Microscopic Organisms 267 3. Coral Reefs .." * . . . 268 II. THE ATMOSPHERE . . . . . . . . 273 III. WATER . . I . . 275 1. Fresh Waters . . , < . . . . ? . , . 275 2. The Ocean . . . . . : . . . . 286 3. Freezing and Frozen Waters, Glaciers, Icebergs . . . 294 IV. HEAT 303 1. Expansion and Contraction 305 2. Igneous Action and Results 306 3. Metamorphism 319 4. Formation of Veins 323 CONTENTS. vii V. THE EARTH A COOLING GLOBE: ITS CONSEQUENCES . . 327 1. General Considerations ...... . 327 2. General Results of the Lateral Pressure . . . . 329 3. Evolution of the Earth's Fundamental Features . . 331 4. Formation of Mountain Chains 334 VI. CONCLUDING REMARKS 342 APPENDIX. 1. Catalogue of American Localities of Fossils . . . . .346 2. Geological Implements, etc. . . .... , 350 INDEX 353 INTRODUCTION. 1. Rock-structure of the earth's crust. Beneath the soil and waters of the earth's surface there is everywhere a base- ment of rocks. The rocky bluffs forming the sides of many valleys, the ledges about the tops of hills and mountains, and the cliffs along sea-shores, are portions of this basement exposed to view. The rocks generally lie in beds ; and these beds vary from a few inches to hundreds of yards in thickness. The differ- ent kinds are spread out one over another, in many alterna- tions. Sometimes they are in horizontal layers ; but very often they are inclined, as if they had been pushed out of their original position. In some regions they are soft and crumbling ; in others they are not only hard, but also crystal- line in texture. Moreover, they are not all found in any one country. By careful study of the rocks of different continents it has been ascertained that the series of beds, if all were in one pile, would have a thickness of 18 or 20 miles. The actual thickness in niost regions is far less than this. These 18 or 20 miles out of the 4,000 miles between the earth's surface and centre are all of the great sphere that are within reach of observation. The series of rocks alluded to overlie, beyond all question, crystalline rocks that are not part of the series. There is good reason for believing, also, that, not many scores of miles below the surface, there are regions of melted rocks or fire seas of great extent. These fiery depths are nowhere open 2 INTRODUCTION. to examination ; yet the rocks ejected in a melted state from volcanoes or from the earth's fissures are supposed to afford indications of what they contain. 2. Facts taught by the arrangement and structure of the rocks. The various rocks afford proof that they were all slowly or gradually made, the lowest in the series, of course, first, and so on upward to the last. The lowest, therefore, belong to an early period of the world, and those above to later periods, in succession. The larger part of them bear evidence that originally they were deposits or accumulations of sand, mud, or pebbles in a shallow ocean, and that the material was laid down or arranged by the waves and currents of the same ocean, just as beds of sand, mud, or gravel are now made off sea-shores, or along sea-beaches ; others indicate that they were formed by the action of the waters of lakes or of rivers ; and others still, that the sands of which they consist were gathered together by the drifting winds, as sands are drifted and heaped up near vari- ous sea-coasts. In many of the rocks there are marks on the layers that were made by the rippling waves, or by the cur- rents, when the material of the bed was loose sand or clay ; or there are cracks though now filled that were opened by the drying sun in an exposed mud-flat; or impressions that were produced by the drops of a fall of rain. Thus the beds themselves make known the conditions under which they were formed, and thereby the depth and outline of the continental seas. Again, in some regions, the rocks, after being consolidated, have been profoundly fractured, and the fissures thus opened have been filled with melted rock proceeding from the depths below. Again, beds have been uplifted and pressed into great folds, and thus mountain-ranges have sometimes been made. They have often, in addition, undergone crystallization over areas thousands, or even hundreds of thousands, of square miles in extent, the original mud-bed becoming in the change a rock INTRODUCTION. 3 like gneiss or granite. Thus also the disturbances or great movements in the earth's crust are registered, and the various steps in the progress may be deciphered. The succession of rocks in the earth's crust is, hence, like a series of historical volumes, full of inscriptions. It is the endeavor of Geology to examine and interpret these inscrip- tions. They are sufficient, if faithfully studied and compared, to make known the progress of the growing continents through all the successive periods in their long history. 3. Facts taught by the fossil contents of rocks. Again, most of the beds contain shells, corals, leaves, and other re- lated forms, called fossils, so named because dug out of the earth, the word being from the Latin fossilis, meaning, that which is dug up. These fossils are the remains of animals or plants once alive over the earth. The shells and corals were formed by animals, just as the shell of a clam is now formed by the animal occupying it, or corals of existing seas by the coral animals. The various species that have left their re- mains in any bed must have been in existence when that bed was in process of formation : they were the living species of the waters and land at the time. The fossils that occur in one range of beds differ more or less in species from those of the next above in the series ; and those of this range of beds are unlike those of the following ; and so on. Since, therefore, each bed contains evidence as to what animals and plants were living when it was forming, the study of the fossils of the successive beds is the study of the succession of living species that haw existed in the earth's history. 4. Objects of Geology, and subdivisions of the science. The preceding explanations afford an idea of the objects of the science of Geology. They are, 1. To study out the system in the earth's features. 2. To ascertain the nature and arrangement of the rocks. 3. To gather from the rocks the successive events in the progress of the sphere, and present the facts as a continuous 4 INTRODUCTION. history ; part of these facts pertaining to rock-making, moun- tain-making, valley-making, and other operations connected with the growth and finishing of the continents; part to changes in the climate, oceanic currents, and other physical conditions of the earth; and part, to the unfolding of the kingdoms of life, or the succession in the plants and animals of the globe. 4. To determine the causes of all that has happened in the earth's history, that it may be understood how rocks were made, fractured, uplifted, folded, and crystallized ; how mountains were made, and valleys, and rivers ; how con- tinents and oceanic basins were made, and how altered in size or outline from period to period; why the climate of the globe changed from time to time ; and how the living species of the globe were exterminated, or otherwise affected by the physical changes in progress. There are, hence, four principal branches of the science : 1. Physiographic Geology, treating of the earth's phys- ical features ; that is, of the system in the exterior features of the earth. This department properly includes, also, the - system of movements in the water and atmosphere, and the system in the earth's climates, and in the other physical agencies or conditions of the sphere. 2. Lithological Geology, treating of the rocks of the globe, their kinds, structure, and conditions or modes of occurrence. The word lithological is from the Greek X/0os, stone, and Xoyo?, discourse. 3. Historical Geology, treating of the succession in the rocks of the globe, and their teachings with regard to the successive conditions of the earth, or to the changes in its oceans, continents, climates, and life. 4. Dynamical Geology, treating of the causes, or the methods, by which the rocks were made, and by which all the earth's changes were brought about. The word dy- namical is from the Greek Si/m/us, power or force. PART I. PHYSIOGRAPHIC GEOLOGY. UNDER the department of Physiographic Geology only a brief and partial review is here made of the general features of the earth's surface. THE EARTH'S FEATURES. 1. General Characteristics. 1. Size and form. The earth has a circumference of about 25,000 miles. Its form is that of a sphere flattened at the poles, the equatorial diameter (7,926 miles) being about 26 \ miles greater than the polar. 2. Oceanic basin and continental plateaus, Nearly three, fourths (more accurately, eight elevenths} of the whole surface are depressed below the rest, and occupied by salt water. This sunken part of the crust is called the oceanic basin, and the large areas of land between, the continents, or continental plateaus. , 3. Subdivisions and relative positions of the oceanic basin and continental plateaus. Nearly three fourths of the area of the continental plateaus are situated in the northern hemisphere, and more than three fourths of the oceanic basin in the south- ern hemisphere. The dry land may be said to be clustered about the North Pole, and to stretch southward in two masses, an Oriental, including Europe, Asia, Africa, and Australasia, and an Occidental, including North and South America. The ocean is gathered in a similar manner about the South Pole, 6 PHYSIOGRAPHIC GEOLOGY. and extends northward in two broad areas separating the Oc- cident and Orient, namely, the Atlantic and Pacific Oceans, and also in a third, the Indian Ocean, separating the southern prolongations of the Orient, namely, Africa and Australasia. The Orient is made, by this means, to have two southern prolongations, while the Occident, or America, has but one. This double feature of the Orient accords with its great breadth ; for it averages 6,000 miles from east to west, which is far more than twice the mean breadth of the Occident (2,200 miles). The inequality of the two continental masses has its paral- lel in the inequality of the Pacific and Atlantic Oceans ; for the former (6,000 miles broad) is more than double the aver- age breadth of the latter (2,800 miles). Thus, there is one Iroad and one narrow continental mass, and one broad and one narrow oceanic area. The connection of Asia with Australia, through the inter- vening islands, is very similar to that of North America with South America. The southern continent, in each case, lies almost wholly to the east of the meridians of the northern ; and the islands between are nearly in corresponding posi- tions, Florida in the Occident corresponding to Malacca in the Orient, Cuba to Sumatra, Porto Eico to Java, and the more eastern Antilles to Celebes and other adjoining islands. It is, therefore, plain that Australia bears the same relation to Asia that South America does to North America. It is also true that Africa is essentially in a similar position with reference to Europe. The northern portion of the Orient, or Europe and Asia combined, makes one continental area ; and its general course is east and west. The northern portion of the Occident, or North America, is elongated from north to south. 4. Oceanic depression and continental elevations. The depth of the oceanic basin below the water-level is possibly in some parts 40,000 feet. The mean depth is much less. The depth across from Newfoundland to Ireland, along what is THE EARTH'S FEATURES. 7 called the telegraphic plateau, is from 6,000 to 15,000 feet. Farther south the depth of the North Atlantic is mostly 12,000 to 19,000 feet ; eighty miles from Bermuda it is 25,500 feet. The mean depth of the North Pacific, between Japan and San Francisco, has been determined by Professor Bache, from the passage of earthquake-waves in 1855, to be 13,000 feet; and that of the South Pacific, between South America and New Zealand, on similar evidence, is about the same. The highest point of the continents that has been measured is 29,000 feet : it is the peak called Mount Everest, in the Himalayas. But the mean height of the continental plateaus is only about 1,000 feet. The mean height of the several continents has been estimated as follows : Of Europe, 670 feet ; Asia, 1,150 feet ; North America, 748 feet ; South America, 1,132 feet ; all America, 932 feet ; Europe and Asia, 1,000 feet ; Africa, probably 1,600 feet ; and Australia, per- haps 500. The material in the Pyrenees, if spread equally over Europe, would raise the surface only 6 feet ; and that of the Alps, only 22 feet. Although some mountain-chains reach to a great elevation, their breadth above a height of 1,000 feet is small compared with that of the continents below this height. 5. True outline of the oceanic depression. Along the oceanic borders the sea is often, for a long distance out, quite shallow, because the continental lands continue on under water with a nearly level surface ; then comes a rather sud- den slope to the deep bed of the ocean. This is the case off the eastern coast of the United States, east and south of New England. Off New Jersey the deep water begins along a line about 80 miles from the shore ; off Virginia this line is 50 to 60 miles at sea ; and thus it gradually approaches the coast to the southward. The slope of the bottom, for the 80 miles off New Jersey, is only 1 foot in 700 feet. The true boundary between the continental plateau and the oceanic depression is the commencement of the abrupt slope. The British Islands are situated on a submerged portion of the 8 PHYSIOGRAPHIC GEOLOGY. European continent, and are essentially a part of that con- tinent, the limit of the oceanic basin being far outside of Ireland, and extending south into the Bay of Biscay. New Guinea is in a similar way proved to be a part of Australia. 6. Surfaces of the continents. The surface of a continent comprises (1) low lands, (2) plateaus or table-lands, and (3) mountain-ridges. The mountain-ridges may rise either from the low lands or the plateaus. The plateaus are great areas of the surface situated several hundred feet, or a thousand feet or more, above the sea, or above the general level of the low lands. They are often parts of the great moun- tain-chains. Sometimes plateaus include a region between mountain-ridges, and sometimes the mass of the mountains themselves out of which the ridges rise. For example, the regions of Northern and Southern New York are plateaus (the former averaging 1,500 feet in height, the latter 2,000 feet) situated within, or on the borders of, the Appalachian chain. Between the Sierra Nevada and the Wahsatch there is a plateau of vast extent, having the Great Salt Lake in its northeastern portion ; its height above the sea averages 4,000 feet; the high ranges of the Humboldt mountains rise out of it. The eastern part of New Mexico is a plateau of about the same elevation, called the Llano Estacado ; and Mexico is situated in another, from which rise various ridges and peaks. The Desert of Gobi, between the Altai and the Kuen- Lun range, is a desert plateau about 4,000 feet high, while the plateau of Thibet, between the Kuen-Lun range and the Himalayas, is 11,500 to 13,000 feet above the sea. Persia and Armenia constitute another plateau. These examples are sufficient to explain the use of the term. 2. System in the Earth's Features. 1. General form of the continents resulting from their reliefs. The continents are constructed on a common model, as follows : they have high borders and a low centre, and are, THE EARTH'S FEATURES. 9 therefore, basin-shaped. Thus, North America has the Appa- lachians on the eastern border, the Eocky chain on the west, and between these the low Mississippi basin. Fig. 1 illus- Fig. 1. trates this form of the continent. In the section, b represents the Rocky Mountain chain on the west, with its double line of ridges at summit ; a, the Washington chain (including the Sierra Nevada and Cascade range), near the Pacific coast ; c, the Mississippi basin ; d, the Appalachian chain on the east. South America, in a similar manner, has the Andes on the west, the Brazilian Mountains on the east, and other heights along the north, with the low region of the Amazon and La Plata making up the larger part of the great interior. Fig. 2 Fig. 2. is a transverse section from west to east (W, E), showing the Andes at a, and the Brazilian Mountains at b. In these sections the height as compared with the breadth is neces- sarily much exaggerated. In the Orient there are mountains on the Pacific side, others on the Atlantic; and, again, the Himalayas, on the south, face the Indian Ocean, and the Altai face the Arctic or Northern Seas. Between the Himalayas (or rather the Kuen- Lun Mountains, which are just north) and the Altai, lies the plateau of Gobi, which is low compared with the enclosing mountains ; and farther west there are the low lands of the Caspian and Aral, the Caspian lying even below the level of the ocean. The Urals divide the 6,000 miles of breadth into i* 10 PHYSIOGRAPHIC GEOLOGY. two parts, and so give Europe some title to its designation as a separate continent. West of their meridian there are again extensive low lands over Middle and Southern Euro- pean Eussia. In Africa there are mountains on the eastern border, and on the western border south of the coast of Guinea ; there are also the Atlas Mountains along the Mediterranean, and the Kong Mountains along the Guinea coast; and the interior is relatively low, although mostly 1,000 to 2,000 feet in ele- vation. In Australia, also, there are high lands on the eastern and western borders, and the interior is low. All the continents are, therefore, constructed on the basin- like model 2. Relation between the heights of the borders and the extent of the adjoining ocean. There is a second great truth with regard to the continental reliefs; namely, that the highest border faces th# largest ocean. By largest ocean is meant not merely greatest in surface, but greatest in capacity, the depth being important in the consideration. The Pacific, both in depth and surface, greatly exceeds the Atlantic ; so the South Pacific exceeds the North Pacific, and the South Atlantic exceeds the North Atlantic. The Indian Ocean is also one of the large oceans ; for it ex- tends eighty degrees of latitude south of Asia, before reaching any body of Antarctic land ; and this is equivalent to 5,500 miles, nearly the mean breadth of the Pacific : moreover, as it is much more free from islands than the Pacific, it is probably the deeper, of the two, and, consequently, yields in capacity to no other ocean on the globe. Each of the continents sustains the truth announced. North America has its great mountains, the Eocky chain, on the side of the great ocean, the Pacific ; and its small moun- tains, the Appalachian, on the side of the small ocean. So, South America has its highest border on the west ; and the Andes as much exceed in elevation and abruptness the Eocky THE EARTH'S FEATURES. 11 chain as the South Pacific exceeds in capacity the North Pacific. The Orient has high ranges of mountains on the east, or the Pacific side, and lower, as those of Norway and other parts of Europe, on the west ; and the Himalayas, the highest of the globe, face the great Indian Ocean (besides being most elevated eastward toward the great Pacific), while the smaller Altai face the small Northern Ocean. In Africa the eastern mountains, or those on the side of the Indian Ocean, are higher than those on that of the Atlantic. In Australia the highest border is on the Pacific side ; for the South Pacific, taking into view its range in front of East Australia, is greater than the Indian Ocean fronting West Australia. Hence the basin-like shape before illustrated is that of a basin with one border much higher than the other ; and with the highest border on the side adjoining the largest ocean. These features have a vast influence in adapting the con- tinents for man. America stands with its highest border in the far west, and with all its great plains and great rivers inclined toward the Atlantic ; for, through the Gulf of Mexico, the whole interior, as well as the eastern border, has its natural outlet eastward. Had the high mountains of the continent been placed on its eastern side, they would have condensed the moisture of the winds before they had traversed the land, and sent it back, in hurrying and almost useless torrents, to the ocean ; but, being on the western, all the slopes, from the Atlantic to the tops of the Eocky Mountains, lie open to the moist winds, and fields and rivers show the good they thus receive. Again, the Orient, instead of rising into Himalayas on the Atlantic border, has its great heights in the remote east, and its vast plains and the larger part of its great rivers, even those of Central Asia, have their natural outlet westward, or toward the same Atlantic Ocean. Thus, as Professor Guyot has said, the vast regions of the world which are best fitted 12 PHYSIOGRAPHIC GEOLOGY. by climate and productions for man are combined into one great arena for the progress of civilization. Both the Orient and the Occident pour their streams and bear a large part of their commerce into a common ocean; and this ocean, the Atlantic, is but a narrow ferriage between them, and vastly better for the union of nations than connection by as much dry land : 3,000 miles of dry land would be, even in the present age, a serious obstacle to intercourse ; while 3,000 miles of ocean draw the east and west only into closer political, commercial, and social relations. PART II. LITHOLOGICAL GEOLOGY. THE term rock, in geology, is applied to all natural for- mations of rock-material, whether solid or otherwise. Not only are sandstones and slates called rocks, but also the loose earth, sand, and gravel of the surface, provided they have been laid out in beds ly natural causes. All sand- stones were once beds of loose sand; and there is every shade of gradation, from the hardest sandstone to the softest sand-bed : so that it is impossible to draw a line between the consolidated and unconsolidated. Geology does not attempt to draw the line, but classes all together as rocks, regarding consolidation as an accident that might or might not happen in the case of the earth's beds or de- posits. Kocks may be studied simply as rocks, that is, with reference to their composition, and collections may be made containing specimens of their various kinds. Again, they may be studied as rock-masses spread out over the earth and forming the earth's crust ; and, with this in view, the condition, structure, and arrangement of the great rock- masses (called sometimes terranes) would come up for con- sideration. The two subjects under Lithological Geology are, therefore: 1. The Constitution of Rocks; 2. The Con- dition, Structure, and Arrangement of Rock-masses, or Ter- ranes. 14 LITHOLOGICAL GEOLOGY. I. CONSTITUTION OP ROCKS. 1. General Observations on their Constituents. Eocks consist essentially of minerals, and the minerals of the common rocks are of four groups : 1. Quartz, or, as it is called in chemistry, silica. 2. Silicates, or compounds of silica and other substances. 3. Carbon, the chief element of charcoal, with carbonic acid and mineral coal. 4. Carbonates, or compounds of carbonic acid and other substances. 1. Quartz, or Silica. Quartz, or silica (consisting of sili- cium and oxygen), far exceeds all other species in abundance. It is one of the hardest of common minerals ; it does not melt before the blow-pipe ; it does not dissolve in water. Its hardness and durability especially fit it for this place of first importance in the material of the earth's founda- tions. It is often seen in crystals of the forms represented in Figs. 3, 4, though generally occurring in grains, pebbles, or masses. It is distinguished ordinarily by its glassy Fig. 3. Fig. 4. , ^. , -11 j aspect, whitish or grayish color, and an absence of all tendency to break with a smooth surface of fracture (a quality of crystals called cleavage). Although usually nearly colorless or white, it is very often reddish, yellowish, brownish (especially smoky brown), and even black ; and the lustre is sometimes very dull, as in chalcedony, flint, and jasper. The sands and pebbles of the sea-shores and gravel-beds are mostly quartz, because quartz resists the wearing action of waters better than any other common mineral. For the same reason, most sandstones and conglomerates consist mainly of quartz. The hardness (on account of which it scratches glass easily), infusibility, insolubility, non-action of acids, and CONSTITUTION OF ROCKS. 15 absence of cleavage are the characters that serve to distin- guish quartz from the other ingredients of rocks. Although quartz is one of the original minerals of the earth's crust, the quartz of rocks is not all directly of mineral origin. Part of it has passed through living beings, either plants or animals ; for some of the lowest species of these kingdoms of life have the power of making siliceous shells or forming siliceous particles or spicules in their texture ; and beds have been made of these microscopic siliceous shells and spicules. The animal species that secrete spicules of silica are the Sponges; and those making siliceous shells are the microscopic forms called Polycystines. The plants making siliceous shells are the microscopic kinds called Diatoms. (See page 61.) 2. Silicates. Silica also occurs in many of the other rock- making minerals, constituting what are called silicates. It exists, thus, in combination with the constituents of the bases alumina, magnesia, lime, potash, soda, the oxides of iron, and a few others. Pure alumina (consisting of aluminum and oxygen), the most important of the above-mentioned bases, is hard, infusi- ble, and insoluble, and therefore adapted to be next in abun- dance to silica. When crystallized, it is the hardest of all known substances, excepting the diamond, it being the gem sapphire. A massive or rock-like variety, reduced to powder, is emery. Magnesia (magnesium and oxygen), well known under the form of calcined magnesia, is as hard as quartz, when crystal- lized, and equally infusible and insoluble. Lime (calcium and oxygen) is common quick-lime. Potash (potassium and oxygen) and soda (sodium and oxygen) are the alkalies ordinarily so called. These three ingredients, or their elements, are found in many silicates. The same is true, for the most part, of the oxides of iron. The compounds of silica and alumina alone are infusible ; but when lime, potash, soda, or an oxide of iron is present, the silicate is fusible ; and 16 LITHOLOGICAL GEOLOGY. this fits them for being the constituents of igneous or volcanic rocks. The following are the most common of these silicates : 1. Feldspar. Feldspar consists of silica and alumina, along with lime, potash, or soda. Common feldspar, or ortho- clase, contains mainly potash, along with the silica and alu- mina; albite contains, in place of the potash, soda; and labradorite, oligoclase, and other kinds of feldspar contain lime as well as soda. The specific gravity is 2.4-2.7. Either of these kinds of feldspar is distinguished from quartz by having a distinct cleavage-structure, the grains or masses breaking easily in two directions with a flat and shining surface. They are nearly as hard as quartz, often white, but sometimes flesh-red. The albite is usually white, and the labradorite often brownish, with often a beautiful play of colors. 2. Mica, Mica consists of silica and alumina, along with potash, lime, magnesia, or oxide of iron. It cleaves easily into tough leaves, thinner than the thinnest paper, and somewhat elastic. On account of its transparency, and its difficult fusibility, it is often used in the doors of stoves. Its most common colors are whitish, brownish, and black. Some micas contain water, that is, are hydrous ; and these hydro- micas, as they are called, are pearly in lustre, feel a little soapy to the fingers, and are sometimes mistaken for talc. The minerals quartz, feldspar, and mica are the con- stituents of granite; and they may be distinguished in it as follows : the grains of quartz, by their more glassy lus- tre, grayer color, and want of cleavage ; the grains of feld- spar, by their cleavage ; the grains of mica, by their very easy cleavage into thin, elastic leaves by means of the point of a knife-blade. 3. Hornblende and Pyroxene. Hornblende and pyroxene consist, alike, of silica along with magnesia, lime, and pro- toxide of iron. They are both of dark-green, greenish-black, and black colors in most of the rocks formed of them, CONSTITUTION OF ROCKS. 17 though sometimes gray and white. Both are cleavable ; but, unlike mica, they are brittle, and never afford flexible or elas- tic folia by cleavage. Hornblende often occurs in slender needle-shaped crystals ; and there are fibrous varieties of each, called asbestus. They are nearly as hard as feldspar, but much heavier than it (specific gravity = 2.8-3.5), and in general much more fusible. 4. Garnet ; Tourmaline ; Andalusite. These are other silicates, of very common occurrence in rocks. They are usually found in crystals distributed through a rock. Gar- net is commonly in dark-red, brownish, or black crystals of 12 or 24 sides (dodecahedrons or trapezohedrons). The Fig. 5. Fig. 6. Fig. 7. first of these forms is represented in Fig. 5, showing garnets distributed through a mica schist. Tourmaline is generally in oblong 3, 6, 9, or 12 sided crystals, shining and black ; also at times blue-black, brown, green, and red. The crystals are common in gneiss and mica schist, and are at times imbedded in quartz (Fig. 6). Andalusite is found in imbedded crystals in clay slate : the form is nearly a square prism. The interior of the crystals is very frequently black or grayish-black at the centre and angles (Fig. 7), while the rest is nearly white ; and this variety is called made, or chiastolite. 18 LITHOLOGICAL GEOLOGY. 5. Talc ; Serpentine. Talc and serpentine are com- pounds of silica and magnesia with water. They both have a greasy feel, especially the talc. Talc is a very soft min- eral, so soft that it does not feel gritty to the teeth. It is often in foliated plates or masses like mica ; but the folia, or leaves, though separating rather easily, and flexible, are not elastic. The usual color is pale green. A massive gran- ular talc, of whitish, grayish, or greenish color, is called soap- stone, or steatite. Serpentine is harder than talc. It is usually a dark-green massive rock, of a very fine-grained texture. It may be cut with a knife, and it differs in this, and also in its being lighter, from compact hornblendic rocks. 3. Carbon, Mineral Coal, Carbonic Acid. 1. Carbon. Car- bon is familiarly known under three names and conditions : /. Diamond; 2. Graphite; 8. Charcoal. The second is the ma- terial of lead-pencils, and is called also black lead, though containing no lead. The diamond is the hardest of all known substances, and graphite y one of the softest. Char- coal is carbon combined with a little oxygen and hydrogen ; it is derived from wood by smothered combustion, and is not known among minerals. 2. Mineral CoaL Mineral coal is carbon combined with some hydrogen and oxygen. Like charcoal, mineral coal was made from wood or plants. The variety burning with a bright flame is called bituminous coal The harder kind, burning with a feeble flame, bluish or yellowish, is anthracite. Broiun coal differs from true bituminous coal in containing more oxygen (20 per cent or more) and giving a brownish-black powder, and also in coming from strata newer than those of the Car- boniferous age. Lignite is a brown coal retaining in part the structure of the original wood, and having an empyreumatic odor when burned. 3. Carbonic Acid is a gas consisting of carbon and oxygen. It composes about 4 parts by volume of 10,000 parts of the atmosphere. It is formed in all combustion of wood or coal, and is given out in the respiration of animals. CONSTITUTION OF ROCKS. 19 4. Carbonates. 1. Carbonate of Lime, or Calcite, the essential ingredient of limestone and marble, consists of carbonic acid and lime. It crystallizes in a great variety of forms, a few of which are represented in Figs. 8, 9. It cleaves easily in three directions with bright surfaces, as may be seen on exam- ining even the grains of a fine white marble. It is rather soft, so as to be easily scratched with a knife ; dissolves in diluted acid (chlorohydric) with effervescence, that is, with an escape of carbonic acid gas; and when heated (as in a lime-kiln or before the blow-pipe) it burns to quick-lime without melting. By its effervescence with acids it differs from all the minerals before mentioned. 2. Dolomite is a carbonate of lime and magnesia ; that is, it differs from calcite in containing magnesia in place of part of the lime. Much of the so-called limestone of the world is magnesian limestone. It closely resembles common limestone, but may be distinguished by its effervescing scarcely at all with acid unless heat be applied. The trial may be made by dropping a particle, as large as half a grain of wheat, into a test-glass containing a mixture, half and half, of chloro- hydric acid and water. The larger part of the carbonate of lime of rocks has been derived directly from shells, corals, and other animal re- mains. Animals take the material of their shells and other stony structures from the waters of the globe, or from the 20 LITHOLOGICAL OEOLOGY. food they eat, through their power of secretion, the same power by which man forms his bones. After death the shells, corals, or bones, which are of ho further use to the species, are turned over to the mineral kingdom to be made into rocks. The immense extent and thickness of the earth's limestone rocks, nearly all of which, the magnesian included, are proba- bly of organic origin, give some idea of the amount of life that has lived and died through past time. The magnesia of the limestones containing it was taken in chiefly, if not wholly, during the process of consolidation ; and it was prob- ably derived from the ocean's waters. Carbonate of lime and silica are the two stony ingre- dients which have been contributed largely by living species to the earth's rock-formations. Mineral coal is an- other material abundantly contributed by the kingdoms of life, the great beds of the coal period and of other eras having been all made from the material of plants. 5, Sand ; Clay. Sand and clay are not minerals : they are mixtures of minute particles of different minerals, produced by the wearing down of different rocks. A large part of common clay is pulverized feldspar mixed with some quartz. Other kinds, having a greasy feel in the fingers, consist of a material derived from the decomposition of feldspar and allied minerals, and are composed of alumina, silica, and water, mixed more or less with quartz and other impurities. 2. Kinds of Rocks. 1. Fragmental and Crystalline Rocks. The minerals of which a rock consists may be either (1) in broken or worn grains or pebbles, like those of sand or clay, or a bed of pebbles; or (2) they may be in crystalline grains, in which case they were formed where they now are at the time of the crystallization of the rock. Such crystalline grains are angular, and in the case of most minerals excepting quartz show surfaces of cleavage. KINDS OF ROCKS. 21 The rocks of the first kind, consisting of fragments of other rocks, are called fragmental rocks ; and those of the latter kind, crystalline rocks. Eocks made from clay, mud, or sand are fragmental rocks no less than those consisting of coarser material; for each particle of the clay or mud is in general a rock-fragment, however minute it may be. Nearly all the earth and clay, sand-beds and pebble-beds, of the globe have been made of material produced by the wear, decomposition, or disaggregation of rocks. Fragmental rocks are often called sedimentary rocks, be- cause formed in general from sediment, or the earth deposited by waters of the ocean, lakes, or rivers. Intermediate between rocks that are obviously either frag- mental or crystalline there are others, of a flinty compactness, which show no distinct grains, and are therefore not easily referred to either division. In the case of such rocks, the geologist, in order to determine the division to which they belong, has to examine the rocks of the beds associated with them. If these associated rocks are fragmental, then the compact beds are probably so also ; but if these are crystal- line, then they are probably related to the crystalline. Expe- rience among rocks is required to decide correctly in all such cases. 2. Metamorphic and Igneous Rocks. The crystalline rocks are either metamorphic or igneous. 1. Metamorphic rocks are those which have been altered or metamorphosed by means of heat. The alteration, when most complete, consists in a complete crystallization of the rock ; and when less so, in a consolidation of it, with some- times no distinct crystallization. Earthy sandstones and clay-rocks have been thus meta- morphosed into granite, gneiss, and mica schist, and ordinary limestone into statuary marble. 2. Igneous rocks are those which have been ejected in a melted state, as from volcanic vents, or from fissures opened to some seat of fires within or below the earth's crust. 22 LITHOLOGICAL GEOLOGY. 3. Calcareous rocks. Calcareous rocks are the limestones. To a great extent they have been formed from pulverized animal relics, such as shells and corals ; and in this case they are properly fragmental or sedimentary beds, although so finely compact that this might not be suspected from their texture. Some limestones have been made from the accumulation and consolidation of very minute shells, called Rhizopods. These shells being no larger than the finest grains of sand, no powdering was necessary. The limestone rocks formed of them are not fragmental in origin. Other calcareous rocks have been deposited from waters holding the material in solution, and are, therefore, of chemi- cal origin. Of this kind is the travertine of Tivoli near Eome in Italy, and of Gardiner's Kiver in the geyser region of the Yellowstone Park, and similar beds in many regions of mineral springs, besides the petrified moss and trees of some marshy places. 4. Massive, schistose, laminated, slaty, shaly rocks. Eocks are termed massive when there is no tendency to break into slabs or plates, as in the case of granite and most conglom- erates ; schistose, when crystalline and breaking into slabs or plates, owing to the arrangement in layers of the mineral ingredients, especially the mica or the hornblende; lami- nated, when splitting into slabs or flagging-stones, but not in consequence of a crystalline structure ; slaty, when dividing easily into thin, even, hard slates, like roofing-slate; shaly, when dividing easily into thin plates like a slate-rock, but the plates irregular and fragile. The term schist is applied to a schistose rock ; flag, to a laminated rock ; slate, to a slaty rock ; shale, to a shaly rock. A hydrous mineral is one containing water ; and a hydrous rock contains a hydrous mineral among its constituents. The kinds of rocks are here described under the four heads: 1. Fragmental Rocks, not calcareous; 2. Metamorphic Eocks, not calcareous ; 3. Calcareous Rocks ; 4. Igneous Rocks. KINDS OF ROCKS. 23 I . Fragmental Rocks. 1. Sandstone, Composed of sand, coarse or fine. When of pure quartz sand, the rock is a siliceous sandstone ; and if very hard and a little pebbly, a grit. When earthy or clayey, it is an argillaceous sandstone, the term argilla- ceous meaning clayey. Argillaceous sandstones are usually laminated, and, when very hard, may make good flagging- stone. 2. Conglomerate. Containing rounded or angular pebbles. If rounded pebbles, the rock is often called a pudding-stone ; and if angular fragments, a breccia; if the pebbles are of quartz, a siliceous conglomerate; if of limestone, a calcareous conglomerate. 3. Shale. Composed of clay or clayey earth, and having a shaly structure. The colors are of all dull shades from gray to black. When the shaly structure is very imperfect and the rock is quite fragile, it is a marlyte. 4. Tufa. A kind of volcanic sandstone, composed of volcanic sand or pulverized volcanic rocks : color, usually browrlish, brownish-yellow, grayish, and reddish. 2. Metamorphic Rocks. 1. Granite. A crystalline rock, consisting of quartz, feld- spar, and mica. Color, usually light or dark gray, or flesh- red, the latter shade derived from a flesh-colored feldspar. The quartz, uncleavable and usually grayish-white in color ; the feldspar, white to flesh-red, and yielding smooth, shining surfaces by cleavage ; the mica, white to black, and affording thin, flexible leaves by cleavage. 2. Gneiss. Like granite in constitution^ but somewhat schistose, owing to the arrangement of the minerals, espe- cially the mica, in planes, and, consequently, having a banded appearance on a surface of fracture transverse to the struc- ture. If the color of the gneiss is dark gray, it is banded usually with black lines. Aloag the micaceous planes it 24 LITHOLOGICAL GEOLOGY. breaks rather easily into slabs, which are sometimes used for flagging. 3. Mica Schist. Related to gneiss, but consisting mainly of mica, with quartz and more or less of feldspar, and, in consequence of the mica, breaking into thin slabs. The slabs have a glistening surface. In regions of mica schist the dust of the roads is often full of shining particles of mica. 4. Syenyte ; * Hornblendic Gneiss ; Hornblendic Schist. Syenyte resembles granite, but contains hornblende in place of mica : the hornblende may be distinguished from mica by its less perfect cleavage, and by the brittleness of the laminae which cleavage, with some difficulty, affords. A rock like gneiss, but containing hornblende in place of mica, is called syenytic gneiss. A black or greenish-black schistose rock consisting almost wholly of hornblende is called hornblende schist. Hyposyenyte is a syenyte without quartz. 5. Hydromica Slate. A slaty fine-grained micaceous slate feeling somewhat greasy to the fingers. It used to be called talcose slate ; but it contains a hydrous mica instead of talc. 6. Chlorite Slate. A slaty rock containing an olive r green mineral called chlorite, which is related to talc in being magnesian, but contains oxide of iron, and is hardly greasy in feel. Color dark green, and often olive-green. 7. Slate, Clay-Slate, or Argillyte. These are different names of roofing-slate and the allied slaty rocks. The texture is hardly at all crystalline, but the slates in the most perfect kinds are hard, smooth in surface, and not absorbent of water. Color blue-black, purplish, greenish, and of other shades. There is a gradual passage of the above rocks from granite into gneiss; froni gneiss into mica schist; and from mica schist, hydromica slate, and chlorite slate into argillyte. 8. Quartz Rock ; Quartzyte. There is also a gradual * In the names of rocks the last syllable is spelt with a "y" instead of an "i," to distinguish them from the names of minerals. The term granite is made an exception, because it is of so common use in general literature. KINDS OF ROCKS. 25 passage, through the more or less complete absence of the feldspar, into a micaceous quartz rock having a schistose structure ; and, by a more or less complete absence of the mica, into a pure massive quartz rock, called also quartzyte. Quartzyte is only a very firmly consolidated sandstone made of quartz sand. The consolidation has been produced by the aid of heat, just as crystallization into gneiss has been produced. For the former the sandstones were purely sili- ceous, or nearly so, and for the latter, earthy sandstones. 9. Itacolumyte. A peculiar laminated quartz rock occurs in many gold-regions, which bends without breaking, when in large thin plates. It contains scales of a hydrous mica, and owes to this its laminated structure, toughness, and flexibility. 3. Calcareous Rocks. a* Uncrystalline. 1. Common Limestone. A compact rock of grayish and other dull shades of color to black. It breaks with little or no lustre, and with either a slightly rough or a smooth sur- face of fracture. Consists essentially of carbonate of lime, though often very impure from the presence of clay or earth. When containing fossils, it is called fossiliferous limestone. When consisting of carbonate of lime and magnesia, it is a magnesian or dolomitic limestone, or dolomite, a kind not distinguishable by the eye from ordinary limestone. For the distinctive characters, see page 19. When impure, and therefore good for making hydraulic lime (lime that will make a cement which sets under water), it is called hydraulic limestone. Many varieties of common limestone are polished and used as marbles ; they have black, reddish, yellow, gray, and other colors. Some kinds contain fossils. 2. Oblyte. A limestone consisting of concretions as small as the roe of fish, or smaller, whence the name, from the Greek MOV, egg. Oolyte or oolitic limestone occurs in all the 26 LITHOLOGICAL GEOLOGY. geological formations, and is forming in modern seas about some coral reefs. 3. Travertine. (See page 22.) Stalactites are limestone concretions, of the form of icicles, hanging from the roofs of caverns ; and Stalagmite is the same material covering their floors. The waters trickling through limestone rocks hold some carbonate of lime in solution (in the state of bicarbon- ate) ; and its deposition, as the dropping water evaporates, produces these concretions and incrustations. to. Crystalline. Granular Limestone ; Statuary Marble. Limestone hav- ing a crystalline granular texture, and, consequently, glisten- ing on a surface of fracture. The pure white kind, looking when broken much like loaf-sugar, is, when of firm texture, the marble used for statuary ; and both this and coarser varieties are employed for marble buildings. Most of the handsome clouded marbles are here included. 4. Igneous Rocks. 1. Granite-like rocks. Granite, syenyte, and hyposyenyte are here included. Yet far the larger part of granite is either of metamorphic origin or vein-formation. Most igne- ous rocks contain little or no quartz. 2. Dioryte consists of a feldspar (albite, or oligoclase) and hornblende; and, though it may be light colored from the abundance of the feldspar, it is usually dark green and greenish-black, from the preponderance of the hornblende. 3. Doleryte consists of the feldspar labradorite with pyrox- ene, and has greenish-black, brownish-black, and black colors. It is also often called trap. It may be either crystalline granular, or of a flinty compactness. It contains also grains of magnetite. Basalt is only a compact variety of doleryte. Didbasyte is a chloritic or hydrous doleryte. 4. Peridotyte is a doleryte containing grains of a green silicate, of a bottle-glass green color, called chrysolyte or olivine. STRATIFIED ROCKS. 27 5. Porphyry, True porphyry consists of feldspar (ortho- clase) in a compact condition, with disseminated crystals of feldspar of a paler color ; so that a polished surface is covered with angular spots. But any rock containing distinct dis- seminated crystals of feldspar is said to be porphyritic. 6. Trachyte. Consists of feldspar, partly glassy, and has a rough surface of fracture. Hornblende is often present, and sometimes quartz. Phonolyte is a feldspathic rock of smoother surface than trachyte, containing hydrous minerals of the zeolite family. 7. Lava. Any rock that has flowed in streams from a volcano, especially if it contains cavities, or, in other words, is more or less scoriaceous. It is usually a dohryte, perido- tyte, or trachyte in composition. 8. Scoria is a light lava, full of cavities, like a sponge; and pumice, a white or grayish feldspathic scoria, having the air-cells long and slender, so that it looks as if it were fibrous. Igneous rocks, like doleryte and trachyte, sometimes take in water when in process of eruption (deriving it from sub- terranean streams or sources), and then become hydrous. Thus dolerytic lava is made into diabasyte, and trachyte into phonolyte. II. -CONDITION, STRUCTURE, AND ARRANGE- MENT OF ROCK-MASSES. The rocks which have been described are the material of which the great rock-masses or terranes of the globe consist. These rock-masses occur under three conditions : 1. The Stratified; 2. Unstratified ; 3. The Vein-form. 1. The Stratified condition. Stratified rocks are those which lie in beds or strata. The word stratum (the singular of strata) is from the Latin, and signifies that which is spread out. The earth's rocky strata are spread out in beds of vast extent, many of them being thousands of square miles in area and thousands of feet in thickness. 28 LITHOLOGICAL GEOLOGY. The stratified rocks exposed to view over the earth far exceed in surface the unstratified. They are the rocks of nearly the whole of the United States and of almost all of North America, and not less of the other continents. Throughout Central and Western New York, and the States south and west, the rocks, wherever exposed, are seen to be made up of a series of beds. And if the beds are less dis- tinct over a large part of New England, it is, in general, only because they have been obscured by the upturning and crys- tallization which the rocks have undergone since they were formed. Fig. 10. The preceding figure represents a section of the rocks along the river below Niagara Falls. It gives some idea of the alternations which occur in the strata. In a total height of 250 feet (165 feet at the Falls, at F, on the right) there are on the left six different strata in view and parts of two others, the upper and lower,. making eight in all. Num- ber 1 is gray argillaceous sandstone ; 2, gray and red argil- laceous sandstone and shale ; 3, flagstone, or hard laminated sandstone ; 4, reddish shale, or marlyte, and shaly sandstone ; 5, shale ; 6, limestone ; 7, shale ; 8, limestone. Only two of these strata, 7 and 8, are in sight at the Falls (at F). The alternations are thus numerous and various in all regions of stratified rocks. Along the canon of the Colorado there are in some places more than 8,000 feet of stratified beds, show- ing their edges in lofty precipices, and in the mountains tow- ering above the adjoining plains. It must not be inferred that the earth is covered by a regular series of coats, the same in all countries ; for this is far from the truth. Many strata occur in New York that are VEINS. 29 not found in Ohio and the States west, and many in South- ern New York that are not in Northern ; and each stratum varies greatly in different regions, sometimes being limestone in one and sandstone in another. A stratum is a bed of rock including all of any one kind that lie together, as either Nos. 1, 2, 3, 4, 5, 6, 7, or 8 in the preceding figure. A formation includes all the various kinds of strata that were formed in one age or period, as the Carboniferous forma- tion or that of the coal era. A subdivision of a formation, including two or more related strata, is often called a group. A layer is one of the subdivisions of a stratum. A stratum may consist of an indefinite number of layers. 2. TJnstratified condition. Unstratified rocks are those which do not lie in beds or strata. Mountain-masses of granite are often without any appearance of stratification. The rock of the Palisades, on the Hudson, stands up with a bold columnar front, and has no division into layers. There are similar rocks about Lake Superior. Most lavas of vol- canoes have flowed out in successive streams ; and, conse- quently, volcanic mountains are generally stratified. But in some volcanic regions the rocks rise into lofty summits with- out stratification. Although true granite bears no marks of proper stratification, it very often passes insensibly into gneiss, which is a stratified rock ; and there is evidence in this fact that granite is, generally, a stratified rock which has lost the appearance of stratification in consequence of the crystallization it has undergone. 3. Vein-form condition. When rocks have been fractured, and the fissures thus made have been filled with rock-mate- rial of any kind, or with metallic ores, the fillings are called veins. Veins are therefore large or small, deep or shallow, single or like a complete network, according to the char- acter of the fractures in which they were formed. They may be as thin as paper, or they may be many yards, or even rods, in width. Figs. 11 to 14 represent some of them. In 30 LITHOLOGICAL GEOLOGY. Fig. 11 there are two veins, a and b; in Fig. 12, a network of thin veins ; in Fig. 13, two of irregular form, a kind not Fig. 11. Fig. 12. uncommon ; in Fig. 14, two large veins, of still more irregu lar character, crossing one another. Fig. 13. Fig. 14. Fig. 15. if Many veins have a banded structure, like Fig. 15. In this vein the layers 1, 3, 6 consist of quartz; 2, 4, of gneis- soid granite ; 5, of gneiss. Most metallic veins are of this kind: the ores lie in one or more bands alternating with other stony bands consisting of different minerals or rock-material, as calcite, quartz, fluoryte, etc. Those veins that have been filled with melted rocks are usually called dikes; they are not banded, and have regular walls, and the rocks are igneous rocks. They are often transversely columnar in structure. Fig. 16 represents a portion of a dike hav- ing this transversely columnar structure. 65 I 4C ',i 1 21 _' f 'j i 2 y 4 ',',! i.i ! 6 ';!' i ij ',' i ^ ^ ( , i 1 * I'M i'% j ' Hi i I ?' 1: i ; ' j ill ,' i . ,! :'; */, '1*1 M 'r! ', ',' 1 1 ( ii' friil 1 i-'; I;, 1 'I 1 ! ii, ii STRUCTURE OF ROCKS. 31 4, Relation of stratified and true unstratified rocks and veins in the earth's crust. The relations of the stratified and unstratified rocks in the earth's crust will be understood after considering the origin of the crust. The crust is believed to be the cooled exterior of a melted globe. After the first crusting over of the surface of the sphere, the ocean commenced at once to make stratified rocks over the exterior through the wear of the crust-rocks, and the strat- ifying of the sand or mud thus made; while the continued cooling, going on very slowly, made unstratified rocks beneath this first crust as its inner portion. The ocean thus worked over and covered up with strata nearly all, if not all, the original unstratified crystalline rocks. Hence, true unstrati- fied rocks that is, those which were unstratified in their first formation are of very small extent over the globe. As mentioned on page 26, even ordinary granite is not generally of this kind. Veins are a result of fractures of the crust ; and they too are of very limited distribution. Geology, consequently, has for its study, chiefly, strati- fied rocks. Nearly all the facts in geological history are derived from rocks of this kind. It is, therefore, important that the various details with regard to their structure and arrangement should be well understood by the student. Stratified Condition. I . Structure. 1. Massive, laminated, and shaly structures, The massive, laminated, and shaly structures of layers have been explained on page 22. The massive is represented in Fig. 17 a; the laminated, in Fig. 17 ~b ; and the shaly, in Fig. 17 c. Sand- stone is more or less laminated, according to the proportion of clay or fine earthy material it contains. The same is true of limestone. 32 LITHOLOGICAL GEOLOGY. 2. Beach structure. The structure of the upper part of a beach is illustrated in Fig. 17 d. Instead of being composed of evenly laid material, it consists of many irregular small layers as deposited or thrown together by the waves during storms. The lower part of the beach has an even slope of usually 5 to 8 degrees, and the sands beneath are in beds having the same slope. Fig. 17. 3. Ebb-and-flow structure. Having portions of the beds obliquely laminated (as shown in Fig. 17 e) while other alter- nate layers are often laminated horizontally. Such a struc- ture is formed where currents intermit at intervals or are reversed, as in the ebb and flow of the tides. 4. Flow-and-plunge structure. Where the waves plunge heavily in connection with a flow of tidal or other currents, the obliquely laminated layer is broken up into wave-like or wedge-shaped parts, as illustrated in Fig. 17 g. This structure is common in stratified drift. 5. Wind-drift structure. Having the subordinate layers dipping in various directions, sometimes curving and some- times straight, as shown in Fig. 17 /. The hills of sand formed by the winds on a sea-coast are usually thus strati- STRUCTURE OF ROCKS. 33 fied. The sands drifted over the rising heaps form layers conforming to the outer surface, and so may slope at all angles. In storms the heaps may be blown away in part, and afterward be completed again ; but then the layers will conform to the new outer surface, and hence have a different direction. In this way, by successive destructions and re- completions, a bed of sand may be made which shall consist of parts sloping in one direction and other parts in directions very different, with numerous abrupt transitions, as illus- trated in the figure. Fig. 18. Pig. 19. 6. Ripple-marks. A gentle flow of water, or its vibration, over mud or sand ripples the surface. Sandstone and clayey rocks are often covered with such ripple-marks (Fig. 18). 7. Rill-marks. When the waters of a spreading or return- ing wave on a beach pass by shells or stones lodged in the sand, the rills furrow out little channels. Fig. 19 shows such rill-marks alongside of shells in a Silurian sandstone. 8. Mud-cracks. When a mud-flat is exposed to the air or sun to dry, it becomes cracked to a few inches or feet in depth. Fig. 20 represents mud-cracks in an argillaceous sandstone. The cracks were subsequently filled with stony 2* c 34 LITHOLOGICAL GEOLOGY. material, which became harder even than the rock itself; so that the filling stands prominent above a weathered surface of the rock : it is actually a network of veins. Tig. 20. Fig. 21. Fig. 22. 9. Rain-prints. The impressions of rain-drops on sand, or a half-dry mud, have often been preserved in the rocks, appearing as in Fig. 21. 10. Concretionary structure. Layers often contain spheres or disks of rock, which are called concretions. They result from a tendency in matter to concrete or solidify around centres. Some are no larger than grains of sand or the roe of fish, as in oolitic limestone (page 25). Others are as large as peas or bul- lets, and others a foot or more in diameter. The granite of the mountains about the Yo- semite, in California, has rounded forms above owing to a concretionary structure thousands of feet in radius. Fig. 22 represents a spherical concretion ; Fig. 23, a rock made up of rounded concretions, showing also that there is sometimes a concentric structure ; Fig. 24, one with flattened concretions. Concretions, are usually globular in sandstones, lenticular STRUCTURE OF ROCKS. 35 in laminated sandstones, and flattened disks in argillaceous rocks or shales. All these kinds are shown in Fig. 25. The Fig. 23. Fig. 24. Fig. 25. balls are sometimes hollow, and the disks mere rings. Fre- quently the concretions have a shell or other organic object Fig. 26. Fig. 27. Fig. 28. at centre (Fig. 26). They are often cracked through the interior (Fig. 27), the outside in such a case having solidified while the inside was still moist, and the latter afterward cracking as it dried : in such a case the cracks may become filled with other minerals, so that the concretion, on being sawn in two and polished, may have great beauty, owing to the crystals (Fig. 28), as of quartz, or the layers, as of agate, which they contain. Such a cavity lined with crystals is called a geode. Sometimes they contain a loose ball with^- in, a concretion within a concretion. Basaltic columns (Fig. 29) are columns of igneous rock. As the rock cools it contracts, and hence it often becomes di- vided into prisms at right angles to the cooling surfaces. In the consolidation there is a tendency to the concretionary structure, as often shown by the tops of the columns being concave, or their becoming so when the rock decomposes. 11. Jointed structure. The rocks of a region are often di- vided very regularly by numerous straight planes of fracture, 36 LITHOLOGICAL GEOLOGY. Fig. 29. all parallel to one another, and cutting through to great depths. Such deep planes of fracture may characterize the rocks over areas hundreds of miles in ex- tent. They are called joints; and a rock thus divided is said to present a jointed structure. In many cases there are two sys- tems of joints in the same region, crossing one another, so that they divide the rock into angular blocks, or give to a "bluff a front like that of a fortification or a broken wall, as shown in Fig. 30, a view from the shores of Cayuga Lake. The direc- tions of such joints are facts which the geologist notes down with care. The divisional planes in Fig. 29 also are called joints. Fig. 30. 12. Slaty cleavage. The term slaty has been explained on page 22. But one important fact regarding the structure is not there stated, which is, that the slates are usually trans- verse to the bedding, that is, they often cross the layers of stratification more or less obliquely, instead of conforming to the layers like the slialy structure. Slaty cleavage is in this respect like the jointed structure ; but it differs in having the planes of fracture or divisional planes so numer- ous that the rock divides into slates instead of blocks. Slaty cleavage is confined to fine-grained argillaceous rocks. If a rock is a coarse argillaceous rock or an argilla- POSITIONS OF STRATA. 37 ceous sandstone, it may have a jointed structure, but will not have the true slaty cleavage. In Fig. 31 the lines of bedding or stratification are shown at a, b, c, d, while the Fig. 32. transverse lines correspond to the direction of the slates. The same is shown in Fig. 32, with the addition of a slight irregularity in the slates along the junction of two layers. 2. Positions of Strata. 1. Original position of strata. Horizontal position. Ordi- nary stratified rocks were once beds of sand or earth, or of other rock-material, spread out by the currents and waves of the ocean, or the waters of lakes or rivers, or by the winds. When the larger portion of the beds over the North Amer- ican continent were formed, the continent lay to a great extent beneath the ocean, as the bottom of a great, though mostly shallow, continental sea. The principal mountain - chains the Eocky Mountains and the Appalachians had not yet been made, and the surface of the submerged land was nearly flat. The fact that those beds were really marine is proved by their containing, in most cases, marine shells, crinoids, or corals, the relics of marine life; and the great extent of the continental seas is indicated by the fact that the beds cover surfaces tens of thousands of square miles in area, some of them reaching from the Atlantic border west- ward beyond the Mississippi. In such great continental seas, having the bottom nearly flat, the deposits made by means of the currents and waves would have been nearly or quite horizontal. As they increased, they would near the surface ; and here the action of the waves would level off 38 LITHOLOGICAL GEOLOGY. the upper surface of the beds, whether accumulations of sand or earth, or of shells or corals. If the bottom over the region were very slowly sinking, the accumulations might go on thickening, and the beds continue to have the same level or horizontal position. Many strata have been formed along the borders of the continents ; and here, also, they take horizontal positions. The bottom of the border of the Atlantic, south of Long Island, is, for eighty miles from the coast-line, so nearly horizontal that it deepens only 1 foot for every 600 to 700 feet; and if the area were above the ocean, no eye would detect that it was not perfectly level. It is obvious that deposits over such a continental border w r ould be very nearly horizontal. The deltas about the mouths of great rivers, like that of the Mississippi, cover sometimes thousands of square miles. They are made of the sands and earth brought down by the river and spread out by the currents of the river and ocean. They are, therefore, examples of the deposition of rock-mate- rial on a scale of great extent ; and various strata have been formed as deltas are formed. The beds of delta-deposits are always hoi*izontal or nearly so. Other beds were originally vast marshes, like the marshes of the present day, only larger. Such was the condition of those beds in the coal-formation that contain coal. Marshes have a horizon- tal surface ; and marsh deposits, as they accumulate, have a horizontal structure. Many coal-beds contain stumps of trees rising out of the coal (Fig. 33) ; and they always stand vertically on the bed, how- ever much the latter may be displaced, showing that the bed was horizontal when it was formed, or when the trees were growing. Exceptions to a horizontal position. When a river empties into a lake or sea, the bottom of which, near its mouth, is Fig. 33. DISLOCATIONS OF STRATA. 39 more or less inclined, the deposits of detritus made by the river will for a while conform to the slope of the bottom, as in Fig. 34. When rivers fall down precipices, they make a steep bank of earth at the foot, whose layers, if any are Fig. 34. observable, take the slope of the bank. The sand-accumula- tions of a sloping beach have the slope of the beach (page 32), or usually a dip of 5 to 8. But these and similar cases of exceptions to a horizontal position are of small extent. 2. Dislocations of strata. Most of the strata of the globe have lost their original horizontal position, and are more or less inclined ; some are even vertical. They are occasionally bent or folded as a quire of paper might be folded, only the folds are miles, or scores of miles, in sweep. They have often also been fractured, and the separated parts have been pushed, or else have fallen, out of their former connections, so that the portion of a stratum on one side of a fracture may be raised inches, feet, or even miles, above that on the other side. It is stated on page 1, that a thickness of rock equal to 18 or 20 miles is open to the geological explorer. This could not be true, were all strata in their original horizontal posi- tion ; for the most that would in that case be within reach would not exceed the height of the highest mountain. But the upturning which the earth's crust has undergone has brought the edges of strata to the surface, and there is hence no such limit: however deep stratified beds may extend, there is no reason why the whole should not be brought up so as to be exposed to view in some parts of the earth's surface. 40 LITHOLOGICAL GEOLOGY. The following are explanations of the terms used in de- scribing the positions of strata : 7. Outcrop. The portions or ledges of strata projecting out of the ground, or in view at the surface (Fig. 35). 2 f Dip. The angle of slope of inclined or tilted strata. In Figs. 35, 36, d p is the direction of the dip. Both the angle of slope and the direction are noted by the geologist : Fig. 35. thus, it may be said of beds, the dip is 50 to the south, or 45 to the northwest, etc. When only the edges of layers are exposed to view, it is not safe to take the slope of the edges as the slope of the layers; for in Fig. 36 the edges on the faces 1, 2, 3, 4 are all edges of the same beds, and only those of the face 1 would give the right dip. The dip is measured by means of instruments called clino- meters. In Fig. 37, a I c d represents a square block of wood, having a graduated arc b c and a plummet hung below a. Placed on the sloping surface A B, the position of the plummet gives the angle of dip. This kind of clinometer is often made in the form of a watch and com- DISLOCATIONS OF STRATA. 41 bined with a compass. It is most convenient for use when it has a square base. In the same figure, e d f represents another clinometer. It has a level on the arm d e; and when the arm d f is placed on the sloping surface, the other arm is Fig. 38. raised until, as shown by this level, it is horizontal ; the dip is the angle between the two arms, as measured on the arc at the joint. To avoid errors from the unevenness of a rock, a board should be laid down first, and the measurement be made on its surface. When the instrument has a square base it is often best to measure the dip by holding it between the eye and the rock, with one edge of the base in the direc- tion of the dipping layers. 3. Strike. The horizontal direction at right angles with the dip, as s t in Fig. 35. The di- rection of the edges of layers on a surface that is quite horizontal is the true strike. 4. Fault. When strata have been fractured and the parts are displaced, as in Fig. 38, the dis- placement along the fracture is called a fault. The coal-beds 1 and 2 in this figure are thus faulted in two places ; and the amount of the fault in either is the number of feet or inches that one part is above or below the other. The downward movement of the middle portion has caused a bending of the layers in contact along one of the fractures. 42 L1THOLOGICAL GEOLOGY. 5. Folds or flexures. The rising or sinking of strata in curving planes, as represented in the following sections, Fig. 39. a '\ A B at Fig. 39, A, B ; and in the natural section, Fig. 40, from the Appalachian Mountains in Virginia. Fig. 40. S.E. In Fig. 39, a x is the axis or axial plane of the fold. 6. Anticlinal. Having the strata sloping away from a common plane in opposite directions, as the layers either side of a x in Fig. 39, A : the axis is here called an anticlinal axis ; and a ridge made up of such strata is an anticlinal ridge. The word anticlinal is from the Greek dvri, in opposite direc- tions, and K:\lva), I incline. 7. Synclinal. Having the strata sloping toward a com- mon plane from opposite directions. In Fig. 39, B, a a?, a x are anticlinal axes, and a' x', between the others, a synclinal axis; or, viewing the former as anticlinal ridges, the latter is a synclinal valley. The word synclinal is from the Greek a\rj, head) : having no prominent head, and only imperfect eyes, if any ; and the shell commonly of two parts called valves, placed either side of the body, whence the common name of most of the species, Bivalves; as the oyster, clam (Figs. 79-81). These species are called Lamellibranchs, because they have thin lamellar gills either side of the body, from lamella, a plate, and branchia, a gill. The body has on either side a thin fold of skin called the pallium or cloak. In Fig. 79, showing the inside of a valve, 1, 2 are impres- sions of the two great muscles by which the animal closes the shell, and p p is the impression of the margin of the mantle or pallium, called the pallial impression. This mantle lies next to the shell, and the shell is secreted by it; the gills are between it and the body of the Mollusk. In Fig. 80, the pallial impression p p has a deep bend or sinus open- ing toward the back margin of the valve. Shells having this sinus in the impression are described as sinupallial, and those without it as integripallial In Fig. 81, of the oyster, there is but one large muscular impression (at 2). 2. Brachiate Mollusks. These are of two orders : 7. Brachiopods: species (Figs. 82, 83) having a bivalve shell, like the Lamellibranchs, but one of the valves dorsal (or over the back), and the other ventral, instead of being on the sides of the body; moreover, the form is symmetrical either side of a middle line ; that is, if a line be dropped from the beak to the opposite edge (as from b to a in Fig. 83), the parts of the shell on the two sides of the line will RADIATES. 57 be equal. A line similarly drawn in the Lamellibranchs divides the valve unequally (as in Fig. 79). The animals have two spiral arms within, which serve as gills. The name Brachiopod, from the Greek fipaxifov, arm, and TTOU?, foot, refers to these arms. 2. Bryozoans: species of minute size like a polyp in exter- nal form, making often cellular corals which, though often in thin plates or incrustations, sometimes delicately branch like a moss, whence the name, from the Greek ftpvov, moss, and doW, animal. They include the Cellepores, Flustras, etc. Fig. 84 shows a number of the animals protruded from their cells. 4. Sub-kingdom of Radiates. There are three grand divisions of Eadiates : Figs. 86-95. RADIATES. 1. Echinoderms : 86, Echinus, the spines removed from half the surface (x |); 87, Star-fish, Palaeaster Niagarensis ; 88, Crinoid, Encrinus liliiformis ; 89, Crinoid, of the family of Cystideans, Callocystites Jewettii. 2. Acalephs : 90, a Medusa, genus Tiaropsis ; 91, Hydra (x 8) ; 92, Syncoryna. 3. Polyps: Fig. 93, an Actinia ; 94, a coral, Dendrophyllia ; 95, part of a branch of a coral of the genus Gorgonia, showing one of the polyps expanded. 1. Echinoderms (Figs. 86 - 89) : having a more or less hard, inflexible exterior, which is often covered with spines, 3* 58 ANIMAL KINGDOM. whence the name, from e^o?, a hedgehog, and Sepfia, skin. The mouth opens downward in all species except in some at- tached species. Among them are : 7. Echinoids, in which the exterior is a solid shell covered with spines, and the mouth opens downward (Fig. 86 the spines are removed from half of the shell) ; 2. The Asterioids, or Star-fishes, in which the exterior is rather stiff, but still flexible, so that the animal flexes it in its movements (Fig. 87) and the viscera extend into the arms ; 3. The Crinoids (including the Coma- tulids), having flexible arms like star-fishes, but the rays and body made of closely fitting solid calcareous species, and hav- ing in the Comatulids arms for attachment, and in the other Crinoids a stem and being thus plant-like. Other kinds are the RolotJmrioids, which are much like the Echinoids in interior structure and the absence of arms, but have no hard exterior shell, and are seldom found fossil ; and the Ophiuroids, or Serpent-stars, which are near the Asteroids, but have the arms very slender, with no groove beneath. 2. Acalephs (Figs. 90 - 92) : having a soft, flexible body, usually of a jelly-like aspect, though rather tough, and mov- ing, when free, with the mouth downward, as the Medusce (Fig. 90). Some of the species called Hydroid Acalephs (Figs. 91, 92), in one of their stages, if not through all, look like Polyps ; and some of these Acalephs form corals, like the Polyps. The Millepores are Acaleph corals. The other spe- cies are mostly too soft to be common as fossils. 3. Polyps (Figs. 93-95) : having a soft body usually at- tached to a support ; a mouth opening upward ; one or more rows of tentacles arranged about the margin of a disk (some- what like the petals of an Aster around its central disk) ; and the mouth situated at the centre of the disk, as in Fig. 93. Most corals are made by polyps. The coral is secreted with- in the polyp in the same manner as bones are secreted within other animals. Figs. 94, 95 represent portions of living cor- als with the polyps expanded. The number of rays in the cells of many modern corals (the Actinoids), is a multiple of PROTOZOANS. 59 six; and that in many of the more ancient corals, those called Cyathophylloids, is a multiple of four. 5. Protozoans. The principal groups of Protozoans important to the geolo- gist are three : 1. The Sponges. Sponges contain in their tissues great numbers of minute spicules, which are, in nearly all species, siliceous ; and these siliceous spicules are found fossil. There Figs. 96-109. RHIZOPODS. Fig. 96, Orbulina universa ; 97, Globigerina rubra ; 98, Textilaria globulosa Ehr. ; 99, Rotalia globulosa ; 99 a, Side-view of Rotalia Boucaua ; 100, Grammostomum phyllodes Ehr. ; 101, Frondicularia annularis ; 102, Triloculina Josephina ; 103 , Nodosaria vulgaris ; 104, Lituola nautiloides ; 105, a, Flabellina rugosa ; 106, Chrysalidina gradata ; 107, a, Cuneolina pavonia; 108, Nummulites nummularia; 109 a, 6, Fusulinacylindrica. are also sponges that have the fibres siliceous throughout. (See page 188.) 2. The Rhizopods. The larger part of them make calcareous Figs. 110-112. in, POLYCYSTINES. Fig. 110, Lychnocamtim lucerna (x 100); 111, Eucyrtidium Mongol- fieri(x 100); 112, Haliralyptia fimbriata (X 75). 60 VEGETABLE KINGDOM. shells, the most of them minute, consisting usually of many cells. They are often called Foraminifera, from the existence of minute perforations through the shells. Some of the species, magnified from 10 to 20 times (excepting the last two, which are of natural size), are represented in Figs. 96-109. Others called Polycystines make minute siliceous shells, con- sisting of many united cells (Figs. 110-112). They differ from the other Ehizopods, further, in having the arrangement of the cells radiate, and not spiral or alternate. II. Vegetable Kingdom. The vegetable kingdom is not divisible into sub-kingdoms like the animal ; for all the species belong to one grand type, the Radiate, the one which is the lowest of those in the ani- mal kingdom. The higher subdvisions are as follow : I. Cryptogams. Having no distinct flowers or proper fruit, the so-called seed being only a spore, that is, a simple cellule without the store of nutriment (albumen and starch) around it which makes up a true seed ; as Ferns, Sea-weed. They include, 1. Thallogens, consisting wholly of cellular tissue; grow- ing in fronds without stems, and in other spreading forms ; as, 7. AlgCB, which include Sea-weeds and also the Confervee, or Frog-spittle, and many allied fresh- water plants ; 2. Lichens, the dry grayish-white and grayish-green plants that cover stones, logs, etc. ; 3. Fungi, including Mushrooms, etc. The Marine Alga:, or Sea-weeds, that are found fossil, and are not microscopic in size, are mostly of the tough leathery kinds, related to the modern Fuci. They are often called by the general term of Fucoids, signifying resembling Fuci. 2. Anogens, consisting wholly of cellular tissue; growing up in short, leafy stems; as, 7. Musci, or Mosses; 2. Liver- worts. 3. Acrogens, consisting of vascular tissue in part, and growing upward; as, 7. Ferns, or Brakes; 2. Lycopods, or the Ground- Pines; 3. Equiseta, or the Horse-tails. CRYPTOGAMS. 61 The Microscopic Algae are sometimes called ProtopJiytes. They are mostly one-celled species : a few consist of a small number of cells united; and these pass into other species, like common mould, which are in threads, simple or branched, made up of many cells. The kinds found fossil are the fol- lowing : 7. Diatoms. Species having a siliceous shell, often quite beautiful in form. Some of the shells are represented, highly magnified, in Figs. 117 to 122. They grow so abundantly in some waters, fresh or salt, as to produce large siliceous beds, the material of which is an excellent polishing powder, and has long been used for this purpose. 2. Desmids. Species making no siliceous shell, consisting of one or more greenish cells (Figs. 180 186, page 108). These are found fossil in flint and hornstone. 3. Nullipores. Coral-like species, growing in stout calca- reous stems or incrusting masses, so-called because having no surface pores or cells. 4. Coccoliths. Microscopic calcareous disks occurring in -, 122 Figs. 113-122. PLANTS. Fig. 113, section of exogenous wood ; 114, fibres of ordinary coniferous wood (Pinus Strobus), longitudinal section, showing dots, magnified 300 times ; 115, same of the Australian conifer, Araucaria Cunningham! ; 116, section of endogenous stem. Figs. 117 to 122, DIATOMS highly magnified; 117, Pinnularia peregrina, Kichmond, Va. ; 118, Pleurosigma angulatum, id. ; 119, Actinoptychus senarius, id. ; 120, Melosira sulcata, id; a, transverse section of the same ; 121, Grammatophora marina, from the salt water at Stonington, Conn. ; 122, Bacillaria paradoxa, West Point. many places over the ocean's bottom, and also found fossil. Named from KOKKOS, seed, and X/#o5, stone. 62 VEGETABLE KINGDOM. II. Phenogams. Having (as the name implies) distinct flowers and seed ; as the Pines, Maple, and all our shade and fruit trees, and the plants of our gardens. They are divided into: 1. Gymnosperms. Having the flowers exceedingly simple, and the seed naked, the seed being ordinarily on the inner surface of the scales of cones, and the wood having a bark and rings of annual growth (Fig. 113) ; as the Pine, Spruce, Hemlock, etc. The name Gymnosperm is from the Greek for naked seed. The Gymnosperms include (1) the Conifers, or the Pine- tribe of plants, usually called evergreens ; and (2) the Cycads, or plants related to the Cycas and Zamia, which have the leaves and look of a Palm (page 162), although, in fruit and wood, true Gymnosperms. The wood of the Conifers is simply woody fibre without ducts, and in this respect, as well as in the flowers and seed, this tribe shows its inferiority to the following subdivision. The fibres, moreover, may be distinguished, even in petrified specimens, by the dots along their surface as seen under a high magnifier. The dots look like holes, though really only thinner spaces. Fig. 114 shows these dots in the Pinus Stro- bus. In other species they are less crowded. In one division of the Conifers, called the Araucarice, of much geological in- terest, these dots on a fibre are alternated (Fig. 115), and the Araucarian Conifers may thus be distinguished. 2. Angiosperms. Having regular flowers and covered seed ; growth exogenous, the plants having a bark and rings of annual growth (Fig. 113) ; as the Maple, Elm, Apple, P^ose, and most of the ordinary shrubs and trees. These plants are called Angiosperms, because the seeds are in seed-vessels ; and also Dicotyledons, because the seed has two cotyledons or lobes. The Gymnosperms and Angiosperms make up the division of plants called Exogens, which is so named from the Greek eo>, outward, and yevvaa), to grow, because growth takes place PHENOGAMS. 63 through annual additions of layers to the outside of the trunk between the wood and the bark, as illustrated in Fig. 113. 3. Endogens. Having regular flowers and seed ; growth endogenous (from ei/Soi>, within, and yei>i>ao>), the plants show- ing, in a transverse section of a trunk, the ends of fibres, and no rings of growth (Fig. 116), and having no bark; as the Palms, Rattan, Reed, Grasses, Indian Corn, Lily. The Endo- gens are Monocotyledons; that is, the seed is undivided, or consists of but one cotyledon. PART III. HISTORICAL GEOLOGY. HISTORICAL GEOLOGY treats of the order of succession in the strata of the earth's crust, and of the changes that were going on during the formation of each bed or stratum, that is, of the changes in the oceans and the land ; of the changes in the atmosphere and climate ; of the changes in the plants and animals. In other words, it is an historical view of the events that took place during the earth's progress, derived from the study of the successive rocks. It is sometimes called stratigrapJiical geology; but this term embraces only a description of the nature and arrangement of the earths strata. By using the means for determining the order of the sev- eral formations mentioned on page 44, and by a careful study of the organic remains (as fossils are often called) contained in the rocks, from the oldest to the most recent, it has been found that a number of great ages in the progress of this life, and in other events of the history, can be made out. The following have thus been recognized : 1. There was first an age, or division of time, when there was no life on the globe ; or, if any existed, this was true only in the later part of the age, and the life was probably of the very simplest kinds. 2. There was next an age when Shells or Mollusks, Corals, Crinoids, and Trilobites abounded in the oceans, when the SUBDIVISIONS IN THE HISTORY. 65 continents were almost all beneath the salt waters, and when there was, throughout far the larger part, as far as fossils show, no terrestrial life. 3. There was next an age when, besides Shells, Corals, Crinoids, Trilobites, and Worms, there were Fishes in the waters, and when the lands, though yet small, began to be covered with vegetation. 4. There was next an age when the continents were at many successive times largely dry or marshy land, and the land was densely overgrown with trees, shrubs, and smaller plants, of the remains of which plants the great coal-beds were made. In animal life there were, besides the kinds already mentioned, various Amphibians and some other Reptiles of inferior tribes. 5. There was next an age when Reptiles were exceed- ingly abundant, far outnumbering and exceeding in variety, and many also in size and even in rank, those of the present day. 6. There was next an age when the Reptiles had dwindled, and Mammals or Quadrupeds were in great numbers over the continents. 7. After this came Man; and the progress of life here ended. The above-mentioned ages in the progress of life and the earth's history have received the following names : 1. Archaean Time or Age. The name is from the Greek for beginning. 2. Age of Invertebrates, or the Silurian Age. 3. Age of Pishes, or the Devonian Age. 4. Age of Coal-Plants, or the Carboniferous Age. 5. Age of Reptiles, or the Reptilian Age. 6. Age of Mammals, or the Mammalian Age. 7. Quaternary Age, or the Age of Man. The first of these ages the Archcean stands apart as pre- paratory to the age of Invertebrates, or the Silurian, when the systems of life, excepting the Vertebrate, were well displayed. 66 HISTORICAL GEOLOGY. The Silurian, Devonian, and Carboniferous ages were alike in many respects, especially in the aspect of antiquity pervad- ing the tribes that then lived, the shells, crinoids, corals, fishes, coal-plants, and reptiles belonging to tribes that are now wholly or nearly extinct. The era of these ages has, therefore, been appropriately called Paleozoic time, the word Paleozoic coming from the Greek TraXato?, ancient, and ftwrj, life. The next age was ushered in after the extinction of many of the Paleozoic tribes ; and its own peculiar life approxi- mated more to that of the existing world. Yet it was still made up wholly of extinct species, and the most prominent of the tribes and genera disappeared before or at its close. This age corresponds to Mediceval time in geological history, and is called Mesozoic time, from the Greek fieao?, middle, and 0)77, life. The next age, as well as the last, was decidedly modern in the aspect of its species, the higher as well as lower. Both are included under the division called Cenozoic time, from the Greek :a>o?7, life (the ai of Greek words always becoming e in English, as, for example, in ether,' from the Greek alOrip). The following are, then, the grand divisions of geological time adopted : I. Archaean Time. II. Paleozoic Time, including, 7. The Age of Invertebrates, or Silurian ; 2. The Age of Fishes, or Devonian ; 3. The Age of Coal-Plants, or Carboniferous. III. Mesozoic Time, including the Reptilian Age. IV. Cenozoic Time, including the Tertiary and Quaternary Ages. The following sections represent the successive formations of the globe, arranged in the order of time, with the subdi- visions corresponding to the Ages and Periods. AGES. SUBDIVISIONS IN THE HISTORY. 67 Fig. 123. PALEOZOIC. AMERICAN PERIODS. FOREIGN SUBDIVISIONS. Wenlock beds. Upper Llandovery Caradoc sandstone. Bala limestone. Llandeilo group. Archaean 68 AGES. HISTORICAL GEOLOG-Y. Fig. 123 (continued). PERIODS. FOREIGN SUBDIVISIONS. Upper Cretaceous. Middle Cretaceous. Lower Cretaceous. In the preceding sections, Archocan is at the bottom, on the left ; above it there are the names Silurian, Devonian, and so on ; and the names of the Periods, Primordial, Canadian, Trenton, etc., dividing off these Ages, on the right. The names of the Periods in the first part of the section (those of the Paleozoic), the first excepted, are derived from the names of American rocks or localities. The names on the other part are mostly European, as the series of rocks it contains (those of Mesozoic and Cenozoic time) are more com- plete in Europe than in America. SUBDIVISIONS IN THE HISTORY. 69 70 HISTORICAL GEOLOGY. The various strata in the formations of an age are very diversified in character, limestones being overlaid abruptly by sandstones, conglomerates, or shales, or either of these last by limestones ; and each may be very different from the following in its fossils. These abrupt transitions in the strata are proofs that there were great changes at times in the conditions of the region where the strata were formed, and the transitions in the kinds of fossils are evidence of great destructions at intervals in the life of the seas. Such transitions, therefore, naturally divide off the ages into smaller portions of time, or periods, as they are called. By transitions similar in kind, but not so great, periods may often be subdivided into still smaller parts, or epochs. The map on page 69 represents the distribution of the rocks of the different ages, as surface-rocks, over the United States and Canada. The areas indicated by the different kinds of lining are stated on the map. The areas left white are of unascertained or doubtful age ; cr. marks outcrops of Cretaceous on the Atlantic border ; C., Cincinnati ; CL, Claiborne ; V., Vicksburg. The Silurian strata may underlie the Devonian, and both Silurian and Devonian the Carboniferous. The black areas of the Carboniferous period do not, therefore, indicate the absence of Devonian and Silurian, but only that the Car- boniferous strata are the surface strata over the region. There may even be exceptions to this remark with regard to the surface strata ; for, over the areas thus marked Car- boniferous, older rocks may occur in some of the bluffs along the valleys, or occupy small areas in the region, which are too limited to be noted on so small a map. The map on page 71 represents the surface-rocks of the State of New York and Canada, the several areas corre- sponding to the periods. For the Silurian, the lines or dots are drawn horizontally, as in the preceding, and for the De- vonian, vertically. There is no Carboniferous, except near the southern border of the State of New York. SUBDIVISIONS IN THE HISTORY. 71 Geological Map of New York and Canada. 72 ARCHAEAN TIME. No. 1. The Archaean. 2. The Primordial Period. 3. The Canadian Period. 4. The Trenton Period. 5. The Niagara Period. 6. The Salina Period. 9. The Upper Helderberg Period. 10. The Hamilton Period. 11. The Chemung Period. 12. The CatskiU Period. Fig. 126. Lower Silurian. Tipper Silurian. Devonian. Silurian. In the section in Fig. 126, the rocks of the successive periods are represented in order, from the Archaean, in North- ern New York, southwestward to the Coal-formation of Penn- sylvania, showing that they succeed one another on the map simply because they come to the surface in succession. The amount of dip and its regularity are greatly exaggerated in the section ; and there is no attempt to give the relative thickness of the beds. GEOGRAPHICAL DISTRIBUTION. 73 L ARCHJEAN TIME. 1. Rocks: Kinds and Distribution. 1. Distribution. The Archsean era commenced with the origin of the earth's crust, and includes the oldest rocks of the globe. Its formations are those upon which the fos- siliferous rocks of the Silurian and subsequent ages have been spread out, and the material out of which most of these later rocks have been made. The Archaean rocks extend around the whole sphere ; but, Fig. 127. Archaean Map of North America. in general, they are concealed from view by subsequent for- mations. In North America they are surface rocks over a large area north of the great lakes, shaped like the letter V, 74 ARCHAEAN TIME. the longer branch of which area runs northwest to the Arctic Ocean, and the shorter, northeast to Labrador. The white area on the following map, in what is now British America, is the portion of the continent here referred to. There is also a small Archaean area in Northern New York (see map page 71) ; the Highlands of Dutchess County, New York, and of New Jersey is Archaean, and so also in part the Blue Ridge of Virginia; another south of Lake Superior; and a few other spots east of the Eocky Mountains. Some high ranges also of the Rocky Mountain region are Archaean. In Europe Archaean rocks are in view in the great iron re- gions of Sweden and Norway, in Bohemia, and in Scotland. 2. Kinds of Rocks, The rocks are mostly crystalline rocks, such as granite, syenyte, gneiss, syenytic gneiss, mica- schist, hornblende schist, chlorite slate, and granular lime- stone. But besides these there are some hard conglomerates, quartz-rocks or gritty sandstones, and slates. The beautiful iridescent feldspar called labradorite (page 16) is a common constituent of some of the coarse crystalline or granitic rocks. An abundance of iron is one characteristic of the beds. The rocks very often contain hornblende, an iron-bearing mineral, or black mica, also iron-bearing. Along with the rocks there are, in some regions, immense beds of iron ore (i i i, in Fig. 128). In Northern New Fig. 128. York the beds are 100 to 200 feet thick. Similar iron-ore beds occur in New Jer- sey, Michigan, south of Lake Superior, and in Missouri. Graphite is common in some places, and constitutes 2 to 30 per cent of some beds, especially of the limestones. 3. Disturbance and Crystallization of the Rocks. The layers of gneiss and other schistose rocks, with the included lime- stones, are nowhere horizontal; but, instead of this, they dip at all angles, and are often flexed or folded in a most complex manner. Fig. 129 represents the folded character of the Archaean rocks of Canada. The folded rocks in this ORIGIN OF THE ROCKS. 75 figure are overlaid by beds that are nearly horizontal, which belong to the Lower Silurian. Owing to the discolations and uplifts which the rocks have undergone, the iron-ore beds look like veins ; and even the strata of crystalline limestone have often a similar vein-like Fig. 129. Fig. 129, by Logan, from the south side of the St. Lawrence in Canada, between Cascade Point and St. Louis Rapids ; 1, Archaean gneiss ; 2, 2, Silurian strata. appearance. Where strata have been thrown up so that the layers stand vertical, the included bed of ore will be vertical also, and will descend downward in the same manner as a true metallic vein ; and through the breaking and faulting of the strata many of those irregularities would result that are so common in veins. Gneiss, micaschist, granular limestone, and other crystal- line rocks have been described on page 23 as metamorpliic rocks, rocks that were once horizontal sandstones, shales, and stratified limestones, and which have been, by some pro- cess, crystallized. The gneiss and schists in Archaean regions, although upturned at all angles, are actually in layers or strata alternating with one another, as common with ordinary sandstones and shales ; and the ore-beds are conformable to the layers of schist and quartzyte in which they occur. 4. Conclusions as to the Origin of the Rocks. The following conclusions hence follow : 1. That the Archa3an rocks here referred to were originally horizontal strata of sandstones, shales, and limestones ; 2. That after their formation they were pushed out of place by some great movement of the earth's crust, which uplifted and folded them, so that now they are nowhere horizontal; 3. That, besides being dis- placed, they were also crystallized, that is, changed into metamorpkic rocks. The thickness of the Archaean rocks of Canada is stated to exceed 30,000 feet. So great an accumulation of marine beds is proof that the era was very long. 76 ARCHAEAN TIME. It is altogether probable that the time of the uplifting and that of the metamorphism were the same. There may have been many such metamorphic epochs in the course of Archaean time. But, since even the latest beds of the Archaean are thus upturned and crystallized, an extensive revolution of this kind must have been a closing event of the age. Fig. 129 shows that the upturning preceded the formation of the lowest Silu- rian beds, for these lie undisturbed over the folded and crys- tallized Archaean. Below the surface Archaean rocks there must be others, constituting the interior portions of the earths crust. If the earth were originally a melted globe, as appears altogether probable, the earth's crust is its cooled exterior. Whenever the crust formed, its surface must have been at once worn by the waves, wherever within their reach, and deposits of sand, pebbles, and clay must have been formed; and in this way the Archaean formations were begun. But at the same time that these surface strata were in progress, the crust would have been increasing in thickness within by the cooling which was continuing its progress. Of the interior rock o*f the crust little is known. 2. Life. The Archaean rocks contain no distinct fossil-plants. If plants existed then, they were Sea-weeds; for remains of none higher than sea-weeds occur in the overlying Lower Silurian formations. It is possible that Licliens existed over the explored rocks ; for such plants away from waters would not have left their remains in the mud or sands of the seas. There may also have been Fungi of simple kinds. But there is reason to believe that Mosses and higher plants were all absent, for none of these have been found in any Lower Silurian strata. The graphite, abundant in some beds in Canada, is probable evidence of the existence of plants, because it is known that GENERAL OBSERVATIONS* 77 Fig. 130. in later times graphite has been formed out of their remains. The limestone beds suggest the idea that there was present either vegetable or animal life ; for almost all limestones (see page 22) are of organic origin. The annexed figure represents what has been regarded as a fossil form, and named Eozoon Cana- dense. It is supposed to have been a coral-like mass made by Protozoans of the class of Khizo- pods, the simplest of all kinds of animal life. Each dark layer in the mass is supposed to mark the position of the animals. Its animal nature has not, however, been placed beyond doubt. Still, it is altogether probable that Rhizopods existed in the waters Eozoon Canadeuse . before the close of the Archaean era, and that the beds of limestone have been made of their minute shells, or else of calcareous Nullipores. 3. General Observations. The large Archaean area on the map, page 73, represents the main portion of the dry land of North America in the later part, or at the close, of the Archaean age ; for it consists of the rocks made during the age, and is bordered on its dif- ferent sides by the earliest rocks of the next age. It is the outline, approximately, of Archcean North America, or the continent as it appeared when the Silurian age opened. It is, therefore, the beginning of the dry land of North America, the original nucleus of the continent. The smaller Archaean areas mentioned appear to have been mountain ridges and islands in the great continental seas. Europe had its Archaean lands at the same time in Scandi- 78 PALEOZOIC TIME. navia, Scotland, Bohemia, and some other points ; and prob- ably each of the other continents was then represented by its spot, or spots, of dry land. All the rest of the sphere, except- ing these limited areas, was an expanse of waters. The facts to be presented under the Silurian age teach that the great but yet unmade continents, although so small in the amount of dry land, were not covered by the deep ocean, but only by comparatively shallow oceanic waters. They lay just beneath the waves, already outlined, prepared to commence that series of formations the Silurian, Devonian, Carbonif- erous, and others which was required to finish the crust for its ultimate continental purposes. Portions may have been at times a few thousands of feet under water, but in general the depth was small compared with that of the ocean. We thus gather some hints with regard to the geography of America in the period of its first beginnings. The outlines of the Northern Archaean area on the map, page 73 the embryo of the continent and the directions of the other Archaean lands are very nearly parallel to the coast lines of the present continent. The Archaean lands, both in North America and Europe, are largest in the more northern latitudes. II. PALEOZOIC TIME. PALEOZOIC TIME includes three ages : 1. The Age of Invertebrates, or Silurian Age. 2. The Age of Fishes, or Devonian Age. 3. The Age of Coal-Plants, or Carboniferous Age. In describing the rocks of these ages over North America, and the events connected with their history, there are four distinct regions to be noted, distinct, because in an impor- tant degree independent in their history. These are, 1. The Eastern border region, or that near the Atlantic bor- der, including Central and Eastern New England, New Bruns- SILURIAN AGE. 79 wick and Nova Scotia,, and the coast region south of New York. 2. The Appalachian region, or that now occupied by the Appalachian Mountain chain, from Labrador on the north, along by the Green Mountains, and the continuation of the heights through New Jersey, Pennsylvania, Virginia, East- ern Tennessee, and so southwestward to Alabama. 3. The Interior Continental region, or that west of the Appa- lachian region, continued over much of the present eastern slope of the Eocky Mountain chain. 4. The Western border and Rocky Mountain region, from the crest of the Rocky Mountains westward. I. AGE OF INVERTEBRATES, or SILURIAN AGE. This Age is called Silurian from the region of the ancient Silures in Wales, where the rocks occur. It was first so named by Murchison. The Age is naturally divided into Lower and Upper Silurian, each corresponding, in America, to three periods, thus : 1. Lower Silurian. 1. Primordial, or Cambrian Period : including the Cam- brian of England, with the Lingula flags. 2. Canadian Period: including the Tremadoc slates, the Skiddaw slates, and Stiper-stones group of Great Britain. 3. Trenton Period : including the Llandeilo flags, Bala limestone, and Caradoc sandstone of Great Britain. 2. Upper Silurian. 1. Niagara Period: including the Wenlock beds of Great Britain, with the Upper Llandovery. 2. Salina Period. 3. Lower Helderlerg Period : including part of the Ludlow beds of Great Britain. 4. Oriskany Period : including the upper part of the Lud- low beds. 80 PALEOZOIC TIME. LOWER SILURIAN. 1. Primordial Period. I. Rocks: Kinds and Distribution. The strata of the Primordial period, in America, over the Interior Continental basin, are exposed to view at intervals from New York to the Mississippi Eiver ; beyond the river, over some parts of the eastern and western slopes of the Rocky Mountains ; and also in Texas. The area on the map of New York and Canada (page 71) is that numbered 2, lying next to the Archaean. There is reason to believe, from the many points at which the strata come to the surface, that they extend over the larger part of the continent outside of the Archsean area represented on the map, page 73, though concealed by other less ancient strata over most of the sur- face. Through the Interior region the lower rocks are in part a sandstone, called the Potsdam sandstone, from a locality in Northern New York. The sandstone beds contain, in many places, ripple-marks (Fig. 18, page 33) ; mud-cracks (Fig. 20).; layers showing the wind-drift and ebb-and-flow structure (Figs. 17 /, e) ; worm-burrows, and also occasionally the tracks of some of the animals of the period. In the Appalachian region in Vermont, north in Canada, and in Pennsylvania, etc., the rocks are slates overlying sandstone, along with some limestone, the whole 2,000 to 7,000 feet or more thick. In the Eastern border region beds of the period occur at Braintree, near Boston, at St. John's, New Brunswick, and on the Labrador coast. These are the oldest of American Primordial rocks, and have been distinctively called the Acadian group. In Great Britain the Primordial rocks are hard sandstones and slates. The uppermost include the Lingula flags. They are most extensively in view in North and South Wales and in Shropshire. The lower portion of the series, of great thick- PRIMORDIAL PERIOD. 81 ness, consisting of slates and other rocks, was named Cam- brian by Sedgwick. In Lapland, Norway, Sweden, and Bohemia, Primordial strata have been observed. If the strata of later date could be removed from the continents, we should probably find the Primordial beds extensively distributed over all the conti- nents. 2. Life. These most ancient of fossiliferous rocks contain no re- mains of terrestrial life. The plants of the period that have left traces in the rocks were all Sea-weeds. Among animals, the sub-kingdoms of Radiates, Mollusks, and Articulates were represented by water-species, and by these only ; there is no evidence that there were any Vertebrates. The older sandstone abounds in many places in a shell smaller, in general, than a finger-nail, related to the modern Lingula (Fig. 131). It is the shell of a Mollusk of the tribe of Brachiopods. It stood on a stem, when alive, as represented in Fig. 82, page 55. These shells are so characteristic of the beds in many regions as to have suggested the name pm Lingula flags, or Lingula sandstone. Among Mollusks there were only Brachiopods for the greater part of the Primordial period ; but in the later division appear some species of La- mellibranchs, Pteropods, Gasteropods, and Cephalopods. Another tribe very prominent among the earliest of the earth's animals is that of Trilobites, of the sub-kingdom of Articulates, and class of Crustaceans. One of the largest of them, and a kind characteristic of the Lower or Acadian division of the Primordial, is represented in Fig. 132, one sixth the natural size. Its total length, when living, must have been eighteen inches or more, and hence it was about as large as any living Crustacean. The specimen figured was found at Braintree, south of Boston. As shown, it had large eyes situated on the head-shield, evidence, 82 PALEOZOIC TIME. LOWER SILURIAN. Pig. 132. as Buckland observed, of the clear waters and clear skies of Primordial time. As no legs are ever found in connec- tion with Trilobites, they are supposed to have had only thin membranous or foliaceous plates for swimming. Tig. 133 shows the track of a large animal (re- duced to one sixth) found by Logan in the Canada beds, which may have been made by one of the great Trilobites as it crawled over the sand. The existence of marine worms among the earliest animals of the globe is proved by the great numbers of worm-holes or burrows in the sandstones, now filled with hard sandstone like that of the rock. They are very similar to the holes- made by such worms in the sands of sea-shores at the pres- ent time. One species has been called Scolitkus linearis. These worm-holes are common in the European as well as American Primordial sand- stones. There were also Crinoids of the sub-kingdom of Eadiates (page 58), for disks from the broken stems of Crinoids are not uncommon. And among Protozoans there were Sponges, and probably the minute Rhizopods (page 59). Sponges among Protozoans, Crinoids among Radiates, TRILOBITE. Paradoxides Harlani (X ft Fig. 133. Track of a Trilobite (x ft PRIMORDIAL PERIOD. 83 Brachiopods and some representatives of other tribes among Mollusks, Worms and Trilobites among Articulates, and Sea- weeds among Plants, made up the living species thus far dis- covered; and in this Primordial population, Trilobites took the lead. There is as yet no evidence that the dry Primor- dial hills bore a Moss or Lycopod, or harbored the meanest Insect, or that the oceans contained a single Fish. 3. General Observations. The ripple-marks, mud-cracks, and tracks of animals pre- served in this most ancient of Paleozoic rocks are records left by the waves, the sun, and the life of the period, as to the extent and condition of the continent in that early era. These markings teach that when the beds were in progress a large part of the continent lay at shallow depths in the sea, so shallow that the waves could ripple its sands ; that over other portions the surface was a sand-flat exposed at low tide ; or a sea-beach, the burrowing-place of worms ; or a mud-flat, that could be dried and cracked under the heat of the sun, or in a drying atmosphere. With such evidences of shallow water or emerged flats in a formation extending widely over the continent, it is a safe conclusion that the North American continent was at the time in actual existence, and probably not far from its present extent ; and, although partly below the sea-level, and in some places deeply so, it was generally at shallow depths. The same may prove to have been true of the other continents. There is, in fact, evidence of other kinds which, taken in connection with the above, leaves little doubt that the existing places of the deep ocean and of the continents were determined even in the first formation of the earth's crust in the early Archaean era, and that, in all the move- ments that have since occurred, the oceans and continents have never changed places. This preservation of markings, seemingly so perishable, on the early shifting sands, is a very instructive fact. They 84 PALEOZOIC TIME. LOWER SILURIAN. illustrate part of the means by which the earth has, through time, been recording its own history. The track of a Trilo- bite, or of a wavelet, is a mould, in sand or earth, into which other sands are cast both to copy and preserve it ; for if the waves or currents that succeed are light, they simply spread new sands over the indented surface, without obliterating the mould ; and so the addition of successive layers only buries the markings more deeply and thus protects them against destruction. When, finally, consolidation takes place, the track or ripple-mark is made as enduring as the rock itself. After the formation in North America of the great Primor- dial sandstone, there was a change in the condition of the surface, especially over the interior of the continent. For limestone strata began then to form where sandstones were in progress before. This change was probaby some increase in the depth and clearness of the Interior Continental sea. Along the borders of this sea that is, in New York and along the Appalachian region from Quebec into Virginia the rock was a sandstone or shale, with some subordinate strata of limestone. 2. Canadian and Trenton Periods. The CANADIAN period is so named from Canada, where the rocks are well displayed and have been most thoroughly studied; and the TRENTON period, from Trenton Falls, just, north of Utica, the river at the Falls running between high bluffs of Trenton limestone. In Great Britain the first of these periods covers the era of the Tremadoc and Skiddaw slates, and the latter that of the Bala limestone and Llandeilo flags. I. Rocks: Kinds and Distribution. In the Primordial period the rock deposits formed over the North American continent were mainly of sands or mud, CANADIAN AND TRENTON PERIODS. 85 making sandstones and shales ; and but little limestone was formed. The Canadian period is one of transition to a third, the Trenton, when limestones were in progress over nearly the whole breadth of the continent, the Appalachian and Arctic regions, as well as the Interior Continental. The rocks of the Canadian period to the eastward in New York and Canada are, 1. A sandstone associated in places with much limestone, and called, in allusion to the limestone, the Calciferous sand-rock ; 2. South of Quebec, shale, sand- stone, and thin beds of limestone, called the Quebec group ; 3. A limestone formation, called the Chazy limestone, from a place of that name in Northern New York. The latter lime- stone (with probably beds of the Quebec group) makes part of the granular limestone or marble of the Green Mountains from Vermont to Connecticut, and has great thickness also in Pennsylvania and Virginia. In the Interior basin the rock of the period is mainly limestone in Iowa and Wisconsin the Lower Magnesian limestone excepting to the north, where the upper part is sandstone (St. Peter's sandstone) and along the south side of Lake Superior, where there is only sandstone. The " Pictured Kocks " are included in it ; and the thick sandstones of Keweenaw Point, remarkable for their intersection by trap dikes and veins of copper, are sup- posed to be of the same period. The Trenton period is the most remarkable limestone-mak- ing era in American geological history. The rock, unlike the Lower Magnesian limestone, is generally full of fossils, shells, crinoidal remains, corals, etc. ; and often these fossils are so crowded together that no spot so large as the end of the finger can be found without one or more of them. The " Birdseye " and " Black Eiver " limestones are the lower strata in succession of the Trenton period. The upper part of the limestone (marble) of the Green Mountains is probably Trenton. The rock of the latter part of the Trenton period (called the Cincinnati epoch), in New York and the Appala- chians, is shale and sandstone, and even in the Interior 86 PALEOZOIC TIME. LOWER SILURIAN. basin the limestones are often, as about Cincinnati, quite clayey or impure. The Utica shale, Lorraine shale, and a small portion of the Hudson Eiver shale of New York, belong to this era. In the Green Mountains, instead of shales and earthy sandstones, there are gneiss, micaschist, quartzyte, etc. The thickness of the rocks of the Canadian and Trenton periods in Pennsylvania is over 7,500 feet ; while in Illinois it is but 750 feet, and in Missouri about 2,000 feet. The rocks of this era in Great Britain are shales and shaly sandstones, with but little limestone. The Tremadoc slates are dark slates over 1,000 feet thick in Wales, passing below into the Lingula flags, and above into the Llandeilo beds. The Llandeilo flags are shaly sandstones ; and, together with the associated shales, they have a thickness of many thousand feet. Above them there are the Caradoc sandstone of Shrop- shire, and the Bala formation, the latter sandy slates and sand- stone, with thin beds of limestone, in Wales. In Scandinavia the rocks are limestone, overlaid by slates and flags ; and in the Baltic provinces of Russia part of the Interior Conti- nental portion of the Eastern Continent they are mainly limestones. 2. Life. The life of these periods, like that of the Primordial, was, as far as evidence has been collected from the American or foreign rocks, wholly marine : no trace of a terrestrial or fresh-water species of plant or animal has been found. The plants found fossil are Sea-weeds. All the sub-kingdoms of animals were represented, with the exception of the Vertebrates. Among Radiates there were Corals and Crinoids ; among Mollusks, representatives of all the several orders; among Articulates, the water-divisions, Worms and Crustaceans. 1. Radiates, The Canadian beds, especially the finer slates and shales, are remarkable for the great abundance CANADIAN AND TRENTON PERIODS. 87 of very delicate plume-like remains of Eadiate life, called Graptolites, from the Greek jpdcf)a), I write. GRAPTOLITES. Fig. 134, Graptolithus Logani, the central portion of a radiating group of stems with parts of the stems ; 135, same, portion of one of the stems, and 135 a, part of steins enlarged; 136, Graptolithus pristis ; 137, 138, Phyllograptus typus; 139, the young of a Graptolite. A few of the kinds are represented in Figs. 134, 135, 137- 139, and one species, from the later part of the Trenton period, in Fig. 136. In the living state there were cells along the notched margin, one for each notch, from which little star-shaped animals extruded themselves. They be- long to the tribe of Hydroids, under Acalephs, described on page 58. Fig. 140 represents one of the Corals of the Trenton. Its shape is that of a curved cone, a little like a short horn, the small end being the lower. At top, when perfect, the cavity of the coral is divided off by plates radiating from the centre. Such corals are called CyathopJiylloid corals, from the Greek /cvaOos, cup, and $>v\\ov, leaf, alluding to the cup full of radi- ating leaves or plates. When living, the coral occupied the interior of an animal similar to that represented in Fig. 93 or Fig. 94 on page 57. Another kind of coral, of a hemispherical form, and made up of very fine columns, is represented in Figs. 141, 142, the latter showing the interior appearance. It is called Chcetetes lycoperdon. Another, of coarser columns, each nearly a sixth of an inch in diameter, is called the Columnaria alveo- 88 PALEOZOIC TIME. SILURIAN. lata. In a transverse section the columns are divided off by horizontal partitions. Masses of this coral have been found that weigh each between two and three thousand pounds. Fig. 143 shows the form of one of the Crinoids, though the stem on which it stood is mostly wanting, and the arms are not entire. The mouth was in the centre above, and the ani- mal was related to the Comatula among star-fishes, from which it differed in being attached to the sea-bottom by means of a jointed stem. There were also true star-fishes in the seas. Figs. 140-151. 143 RADIATES OF THE TRENTON PERIOD. Fig. 140, Petraia corniculum ; 141, 142, Chsetetes lycoperdon ; 143, Lecanocrinus elegans. MOLLUSKS : Fig. 144, Ptilodictya acuta ; 145, Orthis testudinaria ; 146, Orthis occidentalis ; 147, Leptsena sericea ; 148, Avicula (?) Trentonensis ; 149, Pleurotomaria lenticularis ; 150, Orthoceras junceum. ARTICULATES : Fig. 151, Asaphus gigas. 2. Mollusks. Among Mollusks Bryozoans were very com- mon : the fossils are small cellular corals : one is shown in Fig. 144. Brachiopods were still more characteristic of the CANADIAN AND TRENTON PERIODS. 89 period, and occur in vast numbers. Fig. 145 is Orthis testudi- naria; Fig. 146, 0. occidentalis ; Fig. 147, Leptcena sericea. There were also some Lamellibranchs, as Fig. 148, Avicula ? Trentonensis ; and some Gasteropods, as Fig. 149, Pleuroto- maria lenticularis. Shells of Cephalopods were especially common under the form of a straight or curved horn with transverse partitions. Fig. 150, Orthoceras junceum, repre- sents a small species. One kind had a shell 12 or 15 feet long and nearly a foot in diameter. The word Orthoceras is from the Greek o/o#o9, straight, and ice pas, horn. There were some species also of the genus Nautilus. 3. Articulates. Fig. 151 represents one of the large Trilo- bites of the Trenton rocks, the Asaphus gigas, a species sometimes found a foot long. Another Trilobite is the Caly- mene Blumenbachii, represented in Fig. 73, page 54. While Trilobites appear to have been the largest and high- est life of the Primordial seas, Cephalopods, of the Orthoceras family, far exceeded Trilobites in both respects in the Trenton. The larger kinds must have been powerful animals to have borne and wielded a shell 12 or 15 feet long. Although clumsy compared with the fishes of a later age, they emu- lated the largest of fishes in size, and no doubt also in their voracious habits. Crustaceans, in their highest divisions, as the Crabs, may perhaps be regarded by some as of superior rank to Cephalopods. But Trilobites, of the inferior division of Crustaceans, without proper legs, living a sluggish life in slow movement over the sands or through the shallow waters, or skulking in holes, or attached like limpets to the rocks, were far inferior species to the Cephalopods. 3. General Observations. 1. Geography. The wide continental region covered by the Trenton limestone formation, stretching over the Appalachian region on the east, and widely through the Interior basin, must have been throughout a clear sea, densely populated over its bottom with Brachiopods, Corals, Crinoids, Trilobites, 90 PALEOZOIC TIME. and the other life of the era. It may, however, have been a shallow sea ; for the corals and beautiful shells of coral reefs live mostly within 100 feet of the surface. During the later part of the period, or that of the Cincin- nati group, the same seas, especially on the north, became more open to sediment, through some change of level or of coast-barriers, and consequently much of the former life dis- appeared, and other kinds, adapted to impure waters or to muddy bottoms, supplied their places. 2. Disturbances during the Lower Silurian, and at its Close. 7. Igneous ejections in the Lake Superior district. During the progress of the Canadian period there were extensive igneous ejections through fractures of the earth's crust in the vicinity of Lake Superior, about Keweenaw Point and elsewhere ; and probably to some extent also over the bottom or area of the lake itself, for this is indicated by the dikes and columnar trap of Isle Koyale, an island in the lake. These rocks, which were melted when ejected, now stand in many places in bold bluffs and ridges ; and mixtures of scoria and sand make up some of the conglomerate beds of the region. The sandstones,, penetrated by the dikes of trap, and made partly before and partly after the ejection, have a thickness in some places of six or eight thousand feet. There appears to have been a sinking of the region equal to the thickness of the beds, in addition to the igneous ejections. The great veins of native copper of the Lake Superior region are part of the results of this period of disturbance. 2. Emergence of the region of the Green Mountains. The changes from deep to shallow seas, or partly emerged flats, during the Silurian era, are evidence that changes of level, by gentle movements or oscillations in the earth's crust, were going on throughout it. But after the Lower Silurian had closed there appear to have been greater and more permanent changes. The valley of Lake Champlain and the Hudson, as shown by Logan, probably dates from this time. The Green Mountains were probably then made and became part of the LOWER SILURIAN. 91 stable dry land, like the Archaean regions. (See map, page 73.) That they were not dry land before is shown by the Chazy^ and Trenton limestones in their structure, for these are of marine origin ; and that the region was above the water from and after this time is indicated by the fact that the Trenton formations were the latest there formed, and by the still more important observation that near Hudson, in the Hudson River valley, and near Bernardston, in the Connecticut Valley, there are Upper Silurian rocks overlying unconformably the up- turned older rocks. During the progress of the Lower Silurian era a great thick- ness of rock had been made over the Green Mountain region, probably 15,000 or 20,000 feet. These beds were laid down, not in a sea 15,000 or 20,000 feet deep until it was full, but in shallow waters over a bottom that was gradually sinking, and so gradually that the rock-material accumulating over it kept it shallow. Then, when the slowly forming trough had reached this depth, the epoch of catastrophe, that is, of mountain-making, began when the beds were displaced and folded, and consolidated or crystallized. Quartzose sandstones were changed to hard quartzyte, the rock of high ridges in Berkshire and Vermont ; earthy sandstones were made into mica-schist and gneiss; and common limestones came out white or clouded marbles, now extensively quarried for archi- tectural purposes in Canaan, Connecticut, Berkshire County in Massachusetts, and at Eutland and elsewhere in Vermont. Thus, this northern end of the Appalachian region was the first of it to be made into mountains and become part of the stable land ; the rest of it to the south, as well as the cen- tral region of Southern New York, was still receiving, for a long era afterward, new formations, and so preparing for another time of mountain-making, that of the Alleghany range. Besides this uplifting and upturning in Western New Eng- land, there was at the same time, as shown by Safford and Newberry, a bending upward of the Lower Silurian beds along 92 PALEOZOIC TIME. a region extending southwestward from Lake Erie over Cin- ^innati through Kentucky, which area was partly an emerged peninsula or island through the rest of Paleozoic time. In Great Britain and Europe also there were disturbances at the close of the Lower Silurian. The range of Southern Scotland has been referred to this epoch, and so also the Westmoreland Hills, and mountains in North Wales, and hills in Cornwall. 3. Life. There is no evidence that the system of life in its progress during the Lower Silurian had so far advanced as to include a terrestrial species, or the lowest of Vertebrates. Trilobites held the first position in the Primordial Period, Or- thocerata and other Cephalopods in the Trenton. Among Articulates there were neither Myriapods, Spiders, nor In- sects as far as discovered ; for these are essentially terrestrial animals, and the first species of them thus far found are of Devonian age. Among the genera of the Lower Silurian, only four have living species. These are Discina, RJiyncJwnella, and Crania among Brachiopods, and Nautilus among Cephalopods. Lin- gula is supposed by some to be another of this group ; but others make the Silurian species of another genus. These genera of long lineage thus reach through all time from the Lower Silurian onward. All other genera disappear, some at the close of the Primordial, others at that of the Canadian or Trenton period, and some at the termination of subordinate epochs within these periods. The extermination of species took place at intervals through the periods, as well as at their close ; though those at the latter were most universal. With the changes from one stratum to another there were disappearances of some species, and with the changes from one formation to another still larger proportions became extinct. No Primordial spe- cies are known to occur in the Canadian period ; very few of the species of the Canadian period survive into the Trenton ; and very many of those of the early part of the Trenton did UPPER SILURIAN. 93 not exist in the later part. Thus life and death were in pro- gress together, species being removed, and other species ap- pearing as time moved on. 3. Upper Silurian Era. I. Subdivisions. The Upper Silurian era in North America includes four periods : the NIAGARA, the SALINA, the LOWER HELDERBERG, and the ORISKANY. The name of the first is from the Niagara River, along which the rocks are displayed ; that of the second, from Salina in Central New York, the beds being the salt- bearing rocks of that part of the State ; that of the third, from the Helderberg Mountains, south of Albany, where the lower rocks are of this period ; that of the fourth, from Oris- kany, a place in Central New York, northwest of Utica. 2. Rocks: Kinds and Distribution. The rocks of the Niagara period are : 1. A conglomerate and grit-rock called the Oneida conglomerate, which extends from Central New York southward along the Appalachian region, having a thickness of 700 feet in some parts of Penn- sylvania ; together with shaly sandstones of the Medina group, which spread westward from Central New York through Michigan, and also southward along the Appalachian region, being 1,500 feet thick in Pennsylvania ; 2. Hard sandstones, or flags and shales of the Clinton group, having nearly the same distribution as the Medina formation, though a little more widely spread in the west, and about 2,000 feet thick in Pennsylvania ; 3. The Niagara group, occurring in Western New York, and extending widely over both the Appalachian and Interior Continental regions : it consists, at Niagara, of shales below and thick limestone above ; mainly of limestone in the Interior region ; and of clayey sandstone or shales in the Appalachian region, where it has a thickness of 1,500 feet or more. The Niagara is one of the great limestone 94 PALEOZOIC TIME. formations of the continent, existing also in the Arctic regions. Ripple-marks and mud-cracks are very common in the Medina formation. The example of rill-marks figured on page 33 is from its strata in Western New York. The Salina rocks are fragile, clayey sandstones, marlytes, and shales, usually reddish in color, and including a little limestone. They occur in New York and sparingly to the westward, being thickest (700 to 1,00(3 feet thick) in Onon- daga County, New York. The salt of Salina and Syracuse, in Central New York, is obtained from wells of salt water 150 feet and upward in depth, which are borings into these saliferous rocks. From 35 to 45 gallons of the water afford a bushel of salt, while of sea- water it takes 350 gallons for the same amount. No salt is there found in solid masses, but near Goderich, in Canada, at a depth of about 1,000 feet, there is a bed of rock-salt 14 to 40 feet thick. Gypsum is common in some of the beds. The lower beds are the water-lime group, the limestone being hydraulic (page 25). The Lower Helderberg group consists mainly of limestones, and is the second limestone formation of the Upper Silurian. The formation is well developed in the State of New York and along the Appalachian region to the south ; it also occurs in Ohio, Indiana, Southern Illinois, and Tennessee ; also Fig. 152. w Section along the Niagara, from the Falls to Lewiston Heights. along the Connecticut Valley, in Northern Maine, and in New Brunswick and Nova Scotia. The section, Fig. 152, represents the rocks on the Niagara UPPER SILURIAN. 95 \ Eiver at and below the Falls. The Falls are at F ; the whirl- pool, three miles below, at W ; and the Lewiston Heights, which front Lake Ontario, at L. Nos. 1, 2, 3, 4 are different sandstone strata belonging to the Medina group; 5, shale, and 6, limestone, to the Clinton group ; 7, shale, and 8, lime- stone, to the Niagara group. The next section (Fig. 153), Fig. 153. 56 oo ott t> Section of the Salina and underlying strata, from north to south, south of Lake Ontario. from the region south of the eastern part of Lake Ontario, consists as follows : 5 b, Medina group, 5 c, Clinton group, 5d, Niagara group (shale and limestone), 6, Salina beds. (Hall.) The Oriskany beds are mostly rough sandstones. The for- mation extends from Oriskany, New York, southward along the Appalachian region through Pennsylvania, Maryland, and Virginia, where it is several hundred feet thick. It occurs also in Northern Maine, and at Gaspe on the Gulf of St. Lawrence, where the rock is partly limestone. In Great Britain the Upper Silurian rocks are first sand- stones and shales, called, where occurring in South Wales, Llandovery beds, and corresponding to the Medina and Clin- ton groups. Above these there is the Wenlock limestone group, consisting of limestone and some shale (and including, in the upper portion, the Dudley limestone). These rocks occur as surface-rocks near the borders of Wales and England. Next comes the Ludlow group, of the age of the Lower Hel- derberg and Oriskany beds. In Scandinavia the Gothland limestone is the equivalent of the Niagara. 3. Life. The limestone strata and most of the other beds of the Niagara group are full of fossils ; and so also are the rocks of 96 PALEOZOIC TIME. the Lower Helderberg period, and of the Wenlock and Ludlow formations in Great Britain. The Salina formation is desti- tute of them. The life of the era was the same in general features as that of the latter half of the Lower Silurian, though mostly dif- ferent in species. Figs. 154-166. 154 RADIATES : Fig. 154, Zaphrentis bilateralis, Clinton group ; 155, Favosites Niagarensis, Niagara group ; 156, Halysites catenulata, id.; 157, Caryocrinus ornatus, id. MOL- LTTSKS : Fig. 158, Pentamerus oblongus, Clinton gr. ; 159, Orthis biloba (x 2), Niagara gr., and Dudley limestone ; 160, Leptsena transversalis, id. ; 161, Stropliomena rhomboida- lis, id. ; 162, Rhynchonella cuneata, U. S. and Great Britain, id. ; 163, Avicula emacerata, Niagara gr. ; 164, Cyclonema cancellata, Clinton gr. ; 165, Platyceras angulatura, Niagara gr. ARTICULATES : Fig. 166, Homalonotus delphinocephalus, id. The only plants yet found in the Lower Helderberg and underlying beds are Algce, or Sea- weeds ; but in the Oriskany UPPER SILURIAN. 97 beds of Gaspe are found remains of true terrestrial species, re- lated to the Lycopods or modern Ground-pine. They were about as large as the common Lycopodium dcndroideum of the present day. (See page 60.) Similar remains of plants have been found also in the Upper Ludlow beds of Great Britain. In the Animal Kingdom the sub-kingdom of Radiates was represented most prominently by Corals and Crinoids ; that of Mollusks, by species of all the grand divisions, among which the Brachiopod and Orthoceras tribes were the most character- istic, and especially the Brachiopod, whose shells far outnum- ber those of all other Mollusks ; that of Articulates, by Worms, Ostracoids, and Trilobites ; and, before the close of the era, by the new form of Crustaceans represented in Fig. 174 1. Radiates. Fig. 154 is a polyp-coral of the Cyathophyl- loid tribe, showing the radiating plates of the interior ; Fig. 155, a species of Favosites, a genus in which the corals have a columnar structure (somewhat honeycomb-like, whence the name from the Latin favus, honeycomb), and horizontal parti- tions subdivide the cells within ; Fig. 156, Haly sites catenulata, called chain-coral ; Fig. 157, a Crinoid, Caryocrinus ornatus, the arms at the summit broken off; Fig. 89, page 57, another Crinoid of the family of Cystideans, from the Niagara group ; Fig. 87, page 57, a star-fish, also from the Niagara group. 2. Mollusks. Figs. 158 to 162, different Brachiopods of the Niagara period; Figs. 167 to 171, other species charac- teristic of the Lower Helderberg period; Figs. 164, 165, Gas- teropods, and Fig. 163 a Lamellibranch of the Niagara period. Fig. 172 represents small slender tubular cones, called Tentac- ulites, which almost make up the mass of some layers in the Lower Helderberg ; the form of one enlarged is shown in Fig. 173 ; they are regarded as the shells of Pteropods. 3. Articulates. Fig. 166 is a reduced figure of a common Trilobite of the Niagara group, a species of Homalonotus, often having a length of 8 or 10 inches. Fig. 174 represents Eu~ rypterus remipes, a species of a new family of Crustaceans, commencing in the Lower Helderberg ; it is sometimes nearly 98 PALEOZOIC TIME. a foot long. Species of the same family occur in Great Britain in the Ludlow beds, and one of them is supposed, from the fragments found, to have been 6 or 8 feet long, far surpassing any Crustacean now living; Fig. 175, an Ostracoid Crustacean, the Leperditia alta, of unusually large size for the family, modern Ostracoids seldom exceed- ing a twelfth of an inch in length. Figs. 167-175. 168 MOLLTJSKS : Figs. 167, 168, Pentamerus galeatus ; 169, 170, Ehynchonella ventricosa ; 171, Spirifer macropleurus ; 172, Tentaculites irregularis ; 173, id. enlarged. ARTICU- LATES : Fig. 174, Eurypterus remipes, a small specimen ; "175, Leperditia alta. Species all from the Lower Helclerberg group. 4. Vertebrates. The first remains of Vertebrates yet dis- covered occur in the Upper Silurian. They are of fishes, and have been found in the Ludlow beds of Great Britain. They are teeth, scales, and other relics, chiefly of shark-like species. The kinds are further described under the Devonian. 4. General Observations. 1. Geography, On the map, page 69, the areas over which the Silurian formations are surface-rocks are distinguished by UPPER SILURIAN. 99 being horizontally lined. It is observed that they spread southward from the northern Archaean area, and indicate an extension in that direction of the growing continent. South of the Silurian area commences the Devonian, which is vertically lined; and the limit between them shows ap- proximately the course of the sea-shore at the close of the Silurian age. It is seen that more than half of New York, and nearly all of Canada and Wisconsin, had by that time become part of the dry land; but a broad bay covered the Michigan region to the northern point of Lake Michigan, for here Devonian rocks, and to some extent Carboniferous, were afterward formed. The Archaean dry land, the nucleus of the continent, had also received additions in a similar manner on its eastern and western sides, through British America.* But, with all the increase, the amount of dry land in North America was still small. " Europe is proved by similar evi- dence to have had much submerged land. The surface of the earth was a surface of great waters, with the continents only in embryo, one large area and some islands representing that of North America, and an archipelago that of Europe. The emerged land, moreover, was most extensive in the higher latitudes. The rivers of a world so small in its lands must also have been small. The lands, too, according to present evidence, had no green sward over the rocks, except during the closing part of the Silurian age. The succession of Upper Silurian formations is as follows : 1. The Medina sandstone having at base the coarse grit called Oneida conglomerate, occurring of great thickness along the Appalachian region, and reaching north to Central New York, * On the map referred to, page 69, lines of the Silurian and Devonian are seen to extend from the Hudson River southwestward along the Appalachian region. But the outcrop of the Silurian, here represented, is not evidence that there was a strip of dry land along this region from the close of the Silu- rian era, because there is proof that these Appalachian outcrops are a conse- quence of the uplift of the Alleghany Mountains, an event of much later date. (Page 151.) 100 PALEOZOIC TIME. and, besides, spreading westward beyond the limits of that State; 2. The Clinton group of flags and shales, having the same Appalachian extension and great thickness, but spreading on the north much farther westward, even to the Mississippi; 3. The Niagara group, covering the Appalachian region deeply with sandstones and shales, and New York with shales and limestones, and spreading as a great limestone formation through the larger part of t!4eInterior region; then (4) the limited Salina salt-bearing nMrl^fces of New York, ex- tending west through Canada, and AVer part of the Appala- chian region southwest ; then (5} anwther limestone, but im- pure, spreading over New York Stmte and the Appalachian region, and also some of the Statesklvest ; and also occurring in the Connecticut Valley anctovop Maine to the Gulf of St. Lawrence. These facts teach tuW geographical changes took place from time to time, in tha^ourse of the era, corresponding to these several changes in the formations. The clear conti- nental seas of the Trenton period were succeeded by con- ditions fitted to produce Ij^e-^everal arenaceous and argilla- ceous formations, of v^irymor limits, which followed ; but clear waters returned again sN^tiieWpoch. of the Niagara group, when corals, crinoids, and shevtai covered the bottom of the conti- nental sea and made the Niagara limestone formation. But these seas in the Niagara\epoch were less extended than those of the Trenton ; for the 4PP a l acn i an region, instead of being part of the pure sea and making limestones, was receiving great depositions of sand and clay, as if it w r ere at the time a broad reef, or bank, bordering the Atlantic Ocean. The Niagara epoch of limestone-making was followed by the Salina or saliferous period. Since the beds are (1) clays and clayey sands, (2) are almost wholly without fossils, and (3) afford salt, it may be inferred that Central New York was at the time a great salt marsh, mostly shut off from the sea. Over such an area the waters would at times have become too salt to support life, owing to partial evaporation under the hot sun, and too fresh at other times, from the rains. More- UPPER SILURIAN. 101 over, muddy deposits would have been formed ; for they are now common in salt marshes wherever there is, as there was then, no covering of vegetation, and the salt waters would naturally have yielded salt on evaporation in the drier sea- sons. Through an occasional ingress of the sea, the salt waters might have been resupplied for further evaporation. There is direct testimony as to the condition of the land and shallowness of the waters in the regions where many of the rocks were in progress; for ripple-marks and mud- cracks are common in some layers, and are positive evidence that the sands and earth that are now the solid rock were then the loose sands of beaches, sand-flats, or sea-bottoms, or the mud of a salt marsh. Such little markings, therefore, remove all doubt as to the- condition of Central New York in the Salina period. Similar markings indicate^ ; also, the precise condition of the region of the Medina sandstone, showing that there were sand-flats, sea-beaches, and muddy bottoms open to the in- flowing sea. Where the rt&Hpf&ftfc were made (Fig. 19, page 33) the sands of the spot were t^se o a gently sloping flat or beach ; the waters swept lighflyyver the sands, dropping here and there a stray shell (asjfhe Lingula cuneata} or a pebble, which became partly buried; and then, as they retreated, they made a tiny plunge over the little obstacle and furrowed out the loose sand below it. The fineness of the sand, lightness of the shells, and smallness of the furrows are proof that the movements were light. The great thickness of the several formations of the Upper Silurian along the Appalachian region leads to many inter- esting conclusions. It has been stated (page 91) that the Appalachian formations of the earlier Silurian were equally remarkable for their great thickness. The Appalachian re- gion, from the Primordial era onward, was, hence, in strong contrast with the Interior Continental region, where the series of cotemporaneous beds are hardly one tenth as thick. Taking this into connection with another fact, that very 102 PALEOZOIC TIME. many of the strata among the thousands of feet of Silurian formations in the Appalachian region contain those evidences of shallow water and mud-flat or sand-flat origin above ex- plained, there is full proof that in the Silurian era the region was for the most part, as already suggested, a vast sand-reef, ever increasing by new accumulations under the action of the waves and currents of the ocean. It was much of the time a great barrier-reef lying between the open ocean and the Inte- rior Continental sea ; and under its lee, this inner sea, opening southward through the area of the Mexican Gulf, was often in the best condition for the growth of the Shells, Corals, and Crinoids of which the great limestones were made. While the Appalachian region was alike in its general con- dition through the earlier and later Silurian, the limits of the formations in progress during these two eras were somewhat different, as explained on page 91. The part of the Appala- chian region which participated, during the Upper Silurian era, in the great changes connected with the formation of rocks, extended northward from Pennsylvania into New York, and not along the Green Mountains ; the rocks in the State of New York have great thickness for some distance beyond the Pennsylvania border, but thin out about the centre. 2. Life. In the Upper Silurian the highest species of the seas and of the world continued for a while to be Mollusks, of the order of Cephalopods. But before its close there were fishes in the waters, and Vertebrates ever afterward existed as the highest species. Corals and Crinoids were the only kinds of life that had the semblance of flowers. These flower-ani- mals foreshadowed the flowers of the vegetable kingdom for ages before any of the latter existed. The little Lycopods of the later part of the Upper Silurian were flowerless plants, like Ferns. Up to 1872, over 10,000 species of Silurian animals ranging from Sponges to Fishes had been made known through the study of fossils. DEVONIAN AGE. 103 II. AGE OF PISHES, or DEVONIAN AGE. I. Subdivisions. The Devonian formation was so named by Sedgwick and Murchison, from Devonshire, England, where it occurs. The Age may be divided into two eras, an earlier and a later, or that of the lower and that of the upper formations. The Lower Devonian includes the CORNIFEROUS period; the Upper Devonian, the HAMILTON, CHEMUNG, and CATSKILL periods. 2. Rocks: Kinds and Distribution. 1. Earlier and Later Eras. The Lower Devonian is remark- able for a great limestone formation, which spread from New York over a large part of the Interior region, and nearly equalled the Trenton in extent; while the Upper includes very little limestone, the rocks being mainly sandstones, shales, and conglomerates. 2. Comiferous Period. The lowest rocks of this period are fragmental beds, called the Cauda-Galli grit and the Scho- harie grit, having their distribution along the Appalachian region, commencing in Central and Eastern New York and extending southwestward. Next follows the great Comiferous limestone, the lower part of which is sometimes called the Onondaga limestone, and the whole often the Upper Helderlerg group. It stretches from Eastern New York westward to the States beyond the Mississippi. The name Comiferous (derived from the Latin cornu, horn) was given it by Eaton, from its frequently containing a kind of flint called hornstone. This hornstone differs from true flint in being less tough, or more splintery in fracture, though it is like it in hardness and in consisting wholly of silica. The limestone is in many places literally an ancient coral reef. It contains corals in vast numbers and of great variety ; 104 PALEOZOIC TIME. and in some places, as at the Falls on the Ohio, near Louis- ville, Kentucky, the resemblance to a modern reef is perfect. Some of the coral masses at that place are 5 or 6 feet in di- ameter; and single polyps of the Cyathophylloid corals had in some species a diameter of 2 and 3 inches, and in one, of 6 or 7 inches. The same reef-rock occurs near Lake Memphremagog on the borders of Yermont and Canada, and also at Littleton, New Hampshire; but the corals have in these places been partly obliterated by metamorphism. 3. Hamilton Period. The Hamilton formation consists in New York of sandstones and shales, with a few thin layers of limestone. It consists of three parts, corresponding to three epochs : the lower part is called the Marcellus shale ; the middle, the Hamilton beds ; and the upper, the Genesee shale. It has its greatest thickness along the Appalachians. From New York it spreads westward, where it is in part calcareous, and forms the upper part of the "cliff" limestone. It in- cludes a stratum of Hack shale (supposed to be of the epoch of the Genesee shale), 100 to 350 feet thick, which yields in some places 15 to 20 per cent of mineral oil. The formation occurs also in Eastern Maine, New Brunswick, and at Gaspe, on the Gulf of St. Lawrence. The Hamilton beds afford an excellent flagging-stone in Central New York, and on the Hudson River, near Kingston, Saugerties, Coxsackie, and elsewhere, which is extensively quarried and exported to other States. 4. Chemung Period. The Chemung beds are mainly sand- stones, or shaly sandstones, with some conglomerate. They spread over a large part of Southern and Western New York, having great thickness in the Catskill Mountains. A shale of the period in Northern Ohio is called the Erie shale. The formation along the Appalachians is 5,000 feet thick. It thins out to the west of New York, in Ohio, and Michigan. In the following section, taken on a north-and-south line south of Lake Ontario, No. 6 represents the beds of the DEVONIAN AGE. 105 Salina period ; overlaid by 7, the Lower Helderberg lime- stone ; 9, the Corniferous, or Upper Helderberg limestone ; 10, a, b, c, the Hamilton beds ; and 11, the Chemung group. Fig. 176. t> 7 9 10 a Section of Devonian formations south of Lake Ontario. 5. Catskill Period, The rocks are sandstones, shaly sand- stones, and shales ; they occur in Eastern New York, and are 2,000 to 3,000 feet thick in the Catskill Mountains. They also extend southwestward along the Appalachians, being 5,000 to 6,000 feet thick in Pennsylvania. In Great Britain the Devonian rocks include the Old Red Sandstone, the prevailing rock of the age in Wales and Scot- land. The thickness in some places is 8,000 to 10,000 feet. This formation, besides sandstone, includes marlytes of red and other colors, and some limestone. The distribution in Great Britain is shown on the map, page 118. In Germany, in the Rhenish provinces, there is a coral limestone very similar to that of North America. 3. Life. 1. General Characteristics. The Devonian of North America was characterized by forests and an abundance of insects over the land, and by fishes of many kinds in the waters. 2. Plants. Figs. 177-179 represent portions of some of the plants. Fig. 179 is a fragment of a Fern, and Figs. 177, 178, portions of the trees, of the age. The scars or prominences over the surface are the bases of the fallen leaves : a dried branch of a Norway spruce, stripped of its leaves, looks closely like Fig. 178. By referring to page 60, it will there be seen that 5* 106 PALEOZOIC TIME. among the Cryptogams there is one order, the highest, or that of Acrogens, in which the plants have upward growth PLANTS. Fig. 177, Lepidodendron primaevum, from the Hamilton group ; 178, Sigillaria Hallii, ibid. ; 179, Noeggerathia Halliana, from the Chemung group. like ordinary trees, and the tissues are partly vascular : it is the one containing the Ferns, Lycopods, and Equiseta or Horse- tails. The most ancient of land plants belong, to a great ex- tent, to this order, the highest of Cryptogams, and were of the three kinds just mentioned. Another portion are related to the lowest order of flower-bearing plants or Phenogams, called Gymnosperms (see page 62). The groups represented under these divisions are the fol- lowing : I. Flowerless Plants, or Cryptogams, Order of Acrogens. 1. Fern Tribe. The species have a general resemblance to the ferns or brakes of the present time. 2. Lycopods, or plants related to the Ground-Pine. The existing plants of this tribe are slender species, seldom over 4 or 5 feet high : some of the ancient kinds were of the size of DEVONIAN AGE. 107 forest-trees. These ancient species belong mostly to the Lepi- dodendron family, in which the scars are contiguous and are arranged in quincunx order, that is, alternate in adjoining rows, as shown in Fig. 177. The name Lepidodendron is from the Greek A.67T69, scale, and SevSpov, tree, and alludes to the scar-covered trunk, which looks something in surface like a scale-covered reptile. The Ground-Pine of modern woods, although flowerless like the fern, has leaves very similar to those of the Spruce or Cedar (Conifers) ; and this type of plants is intermediate in some respects between the Aero- gens and Gymnosperms (Conifers). The Sigillarids, another family in this tribe, included trees of moderate height, with stout, sparingly branched trunks, bearing long linear leaves much like those of the Lepidoden- drids ; but the scars on the exterior are mostly in parallel vertical lines, as in Fig. 178, and Fig. 222, page 125, and not in quincunx order, like those of the Lepidodendra. The name is from the Latin sigillum, a seal, in allusion to the scars. 3. Equisetum, or Horse-tail Tribe, The Equiseta of mod- era wet woods are slender, hollow, jointed rushes, called sometimes scouring -rushes. They often have a circle of slen- der leaf-like appendages at each joint. The Calamites or Tree- rushes, which are referred to this tribe, are peculiar to the ancient world, none having existed since the Mesozoic. They had jointed striated stems like the Equiseta, and otherwise resembled them. But they were often a score of feet or more in height, and over 6 inches in diameter. Some of them had hollow stems like the Equiseta ; others had the interior of the stems partially woody, and these were intermediate in some respects between the Equiseta and the Gymnosperms. Fig. 225, page 125, represents a portion of one of these plants. II. Flowering Plants, or Phenogams, of the Order of Gymnosperms. Conifers. The species are related to the common Pines and Spruces, or more nearly to the Araucanian Pines of Aus- 108 PALEOZOIC TIME. tralia and South America. The fossils are merely portions of the trunk or branches. Conifers, Ferns, and Lepidodendrids have also been reported from some of the Devonian beds of Britain and Europe. The hornstone, which is massive quartz, or silica, develops, under the microscope, the fact that it was probably made from the siliceous remains of plants and animals. Figs. 180 to 194 represent some of the species which have been detected by Dr. M. C. White in specimens from New York and else- where. Figs. 180 to 186 are microscopic plants, related to Microscopic Organisms from the Hornstone. the Desmids ; Fig. 187 is another kind, called a Diatom, a kind which forms siliceous shells, and which is probably one of the sources of the silica of which the hornstone was made. (See, on Diatoms and Desmids, page 61.) Figs. 188, 189 are spicules of Sponges, also siliceous, and another of the sources of the silica. Figs. 190-192 are probably also sponge-spi- cules. Figs. 193, 194 are fragments of the teeth of some Gasteropod Mollusk. The last is from a hornstone of the Trenton period which was found to afford the same evidences of organic origin. 3. Animals. The early Devonian was the coral period of the ancient world. In no age before or since, not even the present, have coral reefs of greater extent been formed. Among Mollusks, Brachiopods were still the prevailing kinds, though ordinary Bivalves or Lamellibranchs, and DEVONIAN AGE. 109 Univalves or Gasteropoda, were more abundant than in the Silurian. A new type of Cephalopods commenced in the Middle Devonian. Hitherto, the partitions or septa in the shells, straight or coiled, were flat or simply concave; but in the new genus Goniatites the margin of the plate has one or more deep flexures, one of the flexures or pockets being at the middle of the back of the shell. The name is from the Greek yovv, knee or angle. Fig. 205 (page 110) represents one of the species, and Fig. 205 a shows some of the flexures along the back of the shell. Among Articulates there were Worms and Crustaceans, as in earlier time, and the most common Crustaceans were Trilo- bites. Besides these there were the first of Insects, the wings of some species having been reported from the Devonian of New Brunswick. Figs. 195-199. 196 a vrflK . 197 RADIATES. Fig. 195, Zaphrentis Rafinesquii ; 196, 196 a, Cyathophyllum rugosuin ; 197, Syringopora Maclurii ; 198, Aulopora cornuta ; 199, Favosites Goldfussi : all of the Corniferous period. L Radiates. Fig. 195, one of the Cyathophylloid corals, Zaphrentis Rafinesquii ; Fig. 196, another, Cyathophyllum ru- gosum, both from the Falls of the Ohio, and the latter form- ing very large masses. Fig. 196 a is a top view of the cells in Fig. 196. Fig. 199, a Favosites from the same locality, showing well the columnar structure characterizing the genus : 110 PALEOZOIC TIME. the species F. Goldfussi occurs both in America and Europe. Figs. 197 and 198 are small corals from Canada West. 2. Mollusks. Figs. 200 to 202, Brachiopods from the Hamilton beds; Figs. 203, 204, Lamellibranchs, from the Pigs. 200-206. 200 203 MOLLUSKS: Fig. 200, Atrypa aspera ; 201, Spirifer mucronatus; 202, Chonetes setigera; 203, Grammysia bisulcata; 204, Microdon bellistriatus ; 205, 205 a, Goniatites Marcel- lensis : all from the Hamilton group. ARTICULATES : Fig. 206, Phacops bufo, from the Hamilton group. same ; Fig. 205, the Cephalopod, Goniatites Marcellensis, ibid. ; Fig. 205 a, a view of the back, showing the flexures in the partitions, this species having but one flexure or pocket. 3. Articulates. Fig. 206, the Trilobite, Phacops lufo, one of the common species of the Hamilton. The earliest remains of Insects yet discovered have been found in beds DEVONIAN AGE. Ill Fig. 207. supposed to be of the Hamilton era, at St. John's, New Brunswick. A wing of a gigantic species of May-fly is represented in Fig. 207. 4. Vertebrates, The fishes of the Devonian belong to three orders : 1. the Selachians, or Sharks; 2. the Ganoids; and 3. the Placoderms. The Placo- derms are represented in Figs. 208, 209. The name, from the Greek, alludes to the plates that cover the body much like those of a turtle. Some of the Ganoids are shown in Figs. 210-215. The Figs. 208, 209. Platephemera antiqua. VERTEBRATES. Fig. 208, Pterichthys Milled (X |) ; 209, Coccosteus decipiens (X i)- Ganoids are related to the Gar-pike of some modern lakes and rivers, a kind of fish now rarely met with. They have bony, shining scales, and to this the name, from 701*09, shin- ing, alludes. As remarked by Agassiz, they have several 112 PALEOZOIC TIME. characters that ally them to Eeptiles ; that is, (1) they have the power of moving the head at the articulation between the head and the body, the articulation being made by means of a convex and concave surface ; (2) the air-bladder, which an- swers to the lung of higher animals, has a cellular or lung- Pigs. 210-215. 210 GANOIDS. Fig. 210, Cephalaspis Lyellii (x f ) ; 211, 212, scales of same ; 213, Holopty- chins (X i); 214, scale of same; 215, Dipterus macro! epidotus (X ^); 215 a, scale of same. like structure, thus approximating the species to air-breathers; (3) the teeth have in general a structure like that of the early Amphibians. These early species had the tail vertebrated (or heterocercal), as illustrated in Fig. 215. Fig. 210 represents the Cephalaspis, having a flat and broad plate-covered head, with rhombic scales over the body : Fig. 212 shows the DEVONIAN AGE. 113 form of some of the scales. Fig. 215 is a species of Dip- terus, covered with rhombic scales, put on, as in the pre- ceding, much as tiles are arranged on a roof: Fig. 215 a is one of the scales, natural size. Fig. 213 represents another type of Ganoids, having the scales rounded (as shown in Fig. 214) and set on more like shingles; it is a Holoptychius. These figures are all much reduced. Scales of a Holopty- chius have been found in Chemung beds which were over an inch and a half broad, indicating the existence of fishes of great size. The Selachians, or species of the shark tribe, belong in part to the family of Cestracionts (page 53), or that in which the mouth has a pavement of broad bony pieces for grinding. The food in the seas for these carnivorous Fishes consisted Fig. 216. Fin-spine of a Shark ( x |). mainly of shell-fish and mail-clad Ganoids; and grinders were, therefore, well suited for the times. Many of these Cestraciont sharks were of a very large size. Fig. 216 repre- sents a fin-spine of one, drawn two thirds its actual size, found in the Corniferous beds of the State of New York. 4. General Observations. 1. Geography. During the Silurian, there had been a grad- ual gain of dry land on the north, extending the Archaean continent (page 73) southward. This gain continued through the Devonian, so that the formations of the next age, the Car- boniferous, extend only a short distance north of the southern boundary of New York. The sea-shore was thus being set farther and farther southward with the progressing periods. The formations have their greatest thickness along the Ap- palachian region, as in the Silurian age. And both this- fact 114 PALEOZOIC TIME. and their successions lead to similar general conclusions to those stated on page 102. 2. Life. The great feature of the Devonian age is the oc- currence of forests of Acrogens and Conifers; of Insects, among terrestrial Articulates ; and of great Sharks and Gars in the seas, as representatives of Vertebrates. No Mosses appear to have existed as intermediate species between Sea-weeds and the earliest Ferns, Lycopods and Pines. With regard to Fishes, the earliest species belong to the two high groups of the class, the Sharks and the Ganoids; the Ganoids being a type that is partly Eeptilian. The rocks have afforded no evidence of any links between the Mollusk, Worm, or Trilobite and these fishes. III. CARBONIFEROUS AGE, or AGE OF COAL PLANTS. I. General Characteristics: Subdivisions. The Carboniferous age was remarkable, in general, for 1. A low elevation of the continents above the sea-level through long eras alternating with small submergences of the same. 2. Extensive marshy or fresh- water areas over large por- tions of these low continents. 3. Luxuriant vegetation, covering the land with forests and jungles. 4. Scorpions, true Spiders, Centipedes, Insects, over the land, and Amphibians and other Eeptiles over the marshes and in the seas. But, while having these as its main characteristics, it was not an age of continued verdure. There was, first, a long period the Subcarboniferous in which the land was largely beneath the sea ; for limestone, full of marine fossils, is the prevailing rock, and there are but few, and mostly thin coal-beds in the sandstones and shales. This period was fol- lowed by the Carboniferous, or that of the true Coal-measures. CARBONIFEROUS AGE. 115 Yet even in this middle period of the age there were alterna- tions of submerged with emerged continents, long eras of dry and marshy lands luxuriantly overgrown with shrubbery and forest-trees intervening between other long eras of great bar- ren continental seas. Then there was a closing period, the Permian, in which the ocean prevailed again, though with contracted limits ; for the rocks are mainly of marine origin. The Carboniferous period and age were so named from the fact that the great coal-beds of the world originated mainly during their progress. The term Permian was given to the rocks of the third period by Murchison, De Yerneuil, and Keyserling, from a region of Permian rocks in Eussia, the an- cient kingdom of Permia, now divided into the governments of Perm, Yiatka, Kasan, Orenberg, etc. 2. Distribution of Carboniferous Rocks. The Carboniferous areas on the map of the United States, page 69, are the dark areas ; the black cross-lined with white being the Subcarboniferous ; the pure black, the Carboniferous ; the black dotted with white, the Permian. The last occur only west of the Mississippi. The following are the positions of the several great coal areas in North America : 1. EASTERN BORDER EEGION. 1. The Rhode Island area, extending from Newport in Ehode Island northward into Massachusetts. 2. The Nova Scotia and New Brunswick area. II. ALLEGHANY and INTERIOR EEGIONS. 1. The great Al- leghany area, extending from the southern borders of New York and Ohio southwestward to Alabama, covering the larger part of Pennsylvania, half of Ohio, part of Kentucky and Tennessee, and a portion of Alabama. To the northeast, in Pennsylvania, this coal-field is much broken into patches, as shown in the accompanying map of a part of the State, the black areas being those of the coal-district. 2. The Michigan area, covering the central part of the State of Michigan. 116 PALEOZOIC TIME. 3. The Illinois or Eastern Interior area, covering much of Illinois, and part of Indiana and Kentucky. 4. The Missouri, or Western Interior, covering part of Iowa, Minnesota, Missouri, Kansas, Arkansas, and Northern Texas. 5. Besides these, there is a barren Carboniferous region about the slopes and summits of the Kocky Mountains, as around the Great Salt Lake in Utah, and also in California, the workable coal-beds of the Eocky Mountain region being Cretaceous or Tertiary. CARBONIFEROUS AGE. 117 III. ARCTIC KEGION. On Melville Island, and other isl- ands between Grinnell Land and Banks Land, mostly north of latitude 70, and on Spitzbergen and Bear Island north of Siberia. The areas of the coal-measures in North America have been estimated as follows : 1. Rhode Island 500 square miles. 2. Nova Scotia and New Brunswick . 18,000 " " 3. Alleghany . . ; . . . 60,000 " " 4. Michigan. . . . . . 5,000 " u 5. Illinois and Missouri . . . . 120,000 " " But of these, the workable portion probably does not exceed 120,000 square miles. Carboniferous strata occur also in Great Britain and various parts of Europe. The beds in England are distributed over an area between South Wales on the west and the Newcastle basin on the northeast coast (as shown by the black areas on the following map), the most important for coal being the South Wales region ; the Lancashire district, bordering on Manchester and Liverpool; the Yorkshire, about Leeds and Sheffield ; and the Newcastle. In South Wales the thickness of the coal-measures is 7,000 to 12,000 feet, with more than 100 coal-beds, 70 of which are worked. Scotland has some small areas between the Grampian range on the north and the Lammermuirs on the south ; and Ireland, several coal-regions of large extent, as at Ulster, Con- naught, Leinster (Kilkenny) and Munster. The coal-fields of Europe which are most worked are the Belgian, bordering on and passing into France. Germany contains only small coal-bearing areas ; and Eussia in Europe still less, although the Subcarboniferous and Permian rocks cover large portions of the surface. The area of the coal-measures in Great Britain and Ireland is about 12,000 square miles; in Spain, 4,000; in France, 2,000; Belgium, 518. Valuable coal-beds are not found in any rocks older than 118 PALEOZOIC TIME. those of the Carboniferous age, although Wack carbonaceous shales are not uncommon even in the Lower Silurian. They occur, however, in different Mesozoic formations, and also Fig. 218. Fig. 218, Geological Map of England. The areas lined horizontally and numbered 1 are Silurian. Those lined vertically (2), Devonian. Those cross-lined (3), Subcarboniferous. Carboniferous (4), black. Permian (5). Those lined obliquely from right to left, Triassic (6), Lias (7 a), Oolite (7 b), Wealden (8), Cretaceous (9). Those lined obliquely from left to right (10, 11), Tertiary. A is London, B, Liverpool, C, Manchester, D, Newcastle. CARBONIFEKOUS AGE. 119 occasionally in the Cenozoic, but not of the extent which they have in the Carboniferous formations. 3. Kinds of Rocks. 1. Subcarboniferous Period. The Subcarboniferous strata in the Interior Continental region are mainly limestone ; and, as the limestone abounds in many places in Crinoidal re- mains, the rock is often called the Crinoidal limestone. In the Appalachian region, in Middle and Southern Virginia, the rock is also limestone, and has great thickness ; but in North- ern Virginia and Pennsylvania it is mostly a sandstone or conglomerate overlaid by a shaly or clayey sandstone and marlytes of reddish and other colors, the whole having a maximum thickness of 5,000 to 6,000 feet, In the Eastern border region, in Nova Scotia, the rocks are mostly reddish sandstone and marlyte, with some limestone, the estimated thickness 6,000 feet. The prevailing rock in Great Britain and Europe is a lime- stone, called there the Mountain limestone. 2. Carboniferous Period. 7. Rocks of the Coal-formation. - The rocks of the Carboniferous period that is, those of the Coal-measures are sandstones, shales, conglomerates, and occasionally limestones ; and they are so similar to the rocks of the Devonian and Silurian ages that they cannot be distin- guished except by the fossils. They occur in various alter- nations, with an occasional bed of coal between them. The coal-beds, taken together, make up not more than one fiftieth of the whole thickness ; that is, there are 50 feet or more of barren rock to 1 foot of coal. The maximum thickness in Pennsylvania is 4,000 feet; in Nova Scotia, 13,000 feet. The following is an example of the alternations : 1. Sandstone and conglomerate beds . ,. . . . 120 feet. 2. COAL ,- , 6 " 3. Fine-grained shaly sandstone . . . . . 50 " 4. Siliceous iron-ore ....... 1^ " 5. Argillaceous sandstone 75 " 120 PALEOZOIC TIME. 6. GOAL, upper 4 feet shale, with fossil plants, and below a thin clayey layer 7 feet. 7. Sandstone . 80 " 8. Iron-Ore . . . . . : -. . ' .. . '.-. . 5 1 " 9. Argillaceous shale . -.''- .- o^-;*! t . :. t . /. - t QQ u 10. LIMESTONE (oolitic), containing Producti, Crinoids, etc. 11 " 11. Iron- Ore, with many fossil shells . . . . ." . "". 3 " 12. Coarse sandstone, containing trunks of trees . ' .' ' 25 " 13. COAL, lying on 1 foot slaty shale with fossil plants . 5 " 14. Coarse sandstone >'-.-' '.". ; .* ... i .:.; ; V-i. k'.-.i ; 12 " The limestone strata are more numerous and extensive in the Interior Continental region than in the Appalachian; west of the States of Missouri and Kansas limestone is the prevailing rock. Beds of argillaceous iron-ore or clay-ironstone are very com- mon in coal-districts, so that the same region affords ore and the coal for smelting it. Some of the largest iron- works in the world, on both sides of the Atlantic, occur in coal-dis- tricts. The ore is usually the carbonate of iron, impure from mixture with some earth or clay. The coal-beds often rest on a bed of grayish or bluish clay, called the under-day, which is filled with the roots or under- water stems of plants. When this under-clay is absent, the rock below is usually a sandstone or shale. Above the coal- bed the rock may be sandstone, shale, conglomerate, or even limestone ; often the layer next above, especially if shaly, is filled with fossil leaves and stems. In some cases, trunks of old trees rise from the coal and extend up through overlying beds, as in the annexed figure, by Dawson, from the Nova Scotia Coal-measures. Occasionally, as in Ohio and Penn- sylvania, logs 50 to 60 feet long lie scattered through the sandstone beds, looking as if a forest had been swept off from the land into the sea. 2. Coal-Beds. The coal-beds vary in thickness from a fraction of an inch to 30 or 40 feet, but seldom exceed 8 feet, and are generally much thinner : 8 to 10 feet is the thickness of the principal bed at Pittsburg, Pa. ; 29J feet, that of the CARBONIFEROUS AGE. 121 " Mammoth Vein " at Wilkesbarre, Pa. ; 37 J feet, that of one of the two great beds at Pictou in Nova Scotia. In these thick beds, and often also in the thin ones, there are some in- tervening beds of shale, or of very impure coal, so that the whole is not fit for burning. Fig. 219. Section of a portion of the Coal-measures at the Joggins, Nova Scotia, having erect stumps, and also "rootlets " in the under-clays. The coal varies in kind, as explained on page 18, that burn- ing with little flame being called anthracite, and that with a bright yellow flame bituminous coal. When only 12 or 15 per cent of volatilizable substances are present, it is often called semi-bituminous coal. In Pennsylvania the coal of the Pottsville, Lehigh, and Wilkesbarre regions is anthracite ; that of Pittsburg, bituminous coal ; and that of part of the in- termediate district, semi-bituminous, as designated on the map, page 116. The coal also varies as to the impurities present. All of it contains more or less of earthy material, and this earthy material constitutes the ashes and slag of a coal-fire. Ordi- nary good anthracite contains 7 to 12 pounds of impurities in a hundred pounds of coal, and the best bituminous coals 3 to 7. In some coal-beds there is much sulphid of iron or pyrite (a compound of sulphur and iron), and the coal is then unfit for use. It is seldom that the sulphid is altogether absent ; it is the chief source of the sulphur gases that are perceived in the smoke or gas from a coal-fire. 122 PALEOZOIC TIME. Mineral coal, although it seldom breaks into plates unless quite impure, still consists of thin layers. Even the hardest anthracite is delicately banded, as seen on a surface of frac- ture when it is held up to the light. This structure is absent in the variety called Cannel coal, which is a bituminous coal, very compact in texture, feeble in lustre, and smooth in frac- ture. 3. Mineral Oil. Besides mineral coal, the rocks sometimes afford, when heated, liquids consisting of carbon and hydro- gen, called ordinarily petroleum or mineral oil, and bitumen ; when purified for burning it becomes kerosene. Oil-wells are largely worked at Titusville, in Pennsylvania, and about Mecca, in Trumbull County, Ohio, regions of Subcarbonif- erous rocks. The wells are borings into an inferior part of the Subcarboniferous formation, or into the upper part of the Devonian. When a boring reaches the oil-level, the oil rises to the surface, and sometimes issues in a jet. The oil is there- fore in subterranean cavities, and under pressure. It has probably reached those cavities from some subjacent region of oil-yielding shales or limestones. These shales, like the Erie shale of the Chemung period, in Ohio, or the black shale of the Genesee epoch of the Hamilton period, or the Utica shale of the Lower Silurian, are black from the carbonaceous material penetrating them ; and although they do not contain any oil (for the solvents of it take up none from them, or but traces), they contain compounds of carbon and hydrogen (probably oxygenated) which, when the shale is heated, yield the oil or liquid carbo-hydrogen. Thus the shales are oil- yielding, though not oil-containing. The regions of wells are mostly along lines of axes of disturbance ; and probably the heat developed by the movement of disturbance caused the production of the oil and its rising into any opened spaces above. Petroleum is a result of the decomposition of vege- table or animal substances. 4. Salt or Salines. The Subcarboniferous formation in Michigan, in the Saginaw Valley, and in the adjoining region, CARBONIFEROUS AGE. 123 affords extensive salines, and many wells have been opened by boring. The beds affording the saline waters consist of clayey beds or marlytes, shale, and magnesian limestone, and abound also in gypsum, thus resembling those of the Salina period in New York (page 94). 3. Permian Period. The Permian beds are mostly sand- stones and marlytes, with some impure magnesian limestones, and gypsum. They occur in North America west of the Mis- sissippi in Kansas, where they lie conformably over the Car- boniferous. Similar rocks occur in Great Britain in the vicinity of several of the coal-regions, and also in Germany and Eussia. Thin seams of coal are occasionally interstrati- fied with the sandstones, but none of workable extent are known. 4. Life. * 1. Plants. The plants of the forests, jungles, and floating islands of the Carboniferous age, thus far made known, number about 900 species. Among the fossils there are none that afford satisfactory evidence of the presence of either Angiosperms or Palms (page 62) ; for no net- veined leaves, allied in char- acter to those of the Oak, Maple, Willow, Rose, etc., have been found among them ; and no palm-leaves or palm-wood. More- over, the plains were without grass, and the swamps and woods without moss. At the present day Angiosperms, along with Conifers or the Pine family, make up the great bulk of our shrubs and trees ; Palms abound in all tropical countries ; grass covers all exposed slopes where the climate is not too arid ; and mosses are the principal vegetation of most open marshes. The view in Fig. 220 gives some idea of the Carboniferous vegetation over the plains and marshes of the era. The Carboniferous species, like their predecessors in the Devonian age, belonged to the following groups : 124 PALEOZOIC TIME. Fig. 220. CARBONIFEROUS AGE. 125 I. Cryptogams, or Flowerless Plants, Order of Acrogens. 1, Fern Tribe. Ferns were very abundant, a large part of the fossil plants of a coal-region being their delicate fronds (usually called leaves). A portion of a fossil fern is repre- Figs. 221-226. Fig. 221, Lepidodendron aculeatum ; 222, Sigillaria oculata; 223, Stigmaria ficoides ; 224, Sphenopteris Gravenhorstii ; 225, Calamites eannaeformis ; 226, Trigonocarpus tricuspi- datus. sented in Fig. 224. Besides small species, like the common kinds of the present day, there were Tree-ferns, species that 126 PALEOZOIC TIME. had a trunk, perhaps 20 or 30 feet high, and which bore at top a radiating tuft of the very large leaf-like fronds, resem- bling the modern tree-fern of the tropics. One of the tree- ferns of the Pacific is represented in Fig. 220, near the middle of the view, and smaller ferns in front of it below. Tree- ferns, however, were not very common in the Carboniferous forests. The scars in fossil or recent tree-ferns are many times larger than those of Lepidodendrids, and the fossils may be thus distinguished. 2. Lycopodium Tribe. 1. The Lepidodendrids appear to have been among the most abundant of Carboniferous forest- trees, especially in the earlier half of the Carboniferous Age, or to the middle of the Coal Period. They probably covered both the marshes and the drier plains and hills. Some of the old logs now preserved in the strata are 50 to 60 feet in length, strikingly contrasting with the little Ground- Pines of modern times ; and the pine-like leaves were occasionally a foot or more long. The taller tree to the left, on page 124, is a Lepi- dodendron. Fig. 221 shows the surface-markings of one of the species, natural size. 2. Sigillarids. The Sigillarice were a very marked feature of the great jungles and damp forests of the Coal period. They grew to a height sometimes of 30 to 60 feet ; but the trunks were seldom branched, and must have had a stiff, clumsy aspect, although covered above with long, slender, rush-like leaves. Fig. 222 represents a common species, ex- hibiting the usual arrangement of the scars in vertical lines, and also indicating, by the difference in the scars of the right row from those of the others, their difference of form on the outer surface of the tree and beneath the surface. 3. StigmaricB. The fossil Stigmarice are stout stems, gen- erally 2 to 3 or more inches thick, having over the surface distinct rounded punctures or depressions. Fig. 223 is a por- tion of the extremity of a stem, showing the rounded depres- sions and also the leaf-like appendages occasionally observed. The stems or branches are a little irregular in form, and spar- CARBONIFEROUS AOE. 127 ingly branched. They have been found spreading, like roots, from the base of the trunk of a Sigillaria, and sometimes also from that of a Lepidodendron ; and they are hence regarded either as the roots or subaqueous stems of these trees. They are an exceedingly common fossil, especially in the under- clays of the Coal-measures (p. 120). 3. Equisetum Tribe. Fig. 225 represents a portion of one of the tree-rushes, or Catamites, of the Equisetum or Horse- tail tribe. The specimens were very abundant in the great marshes, through the whole of the Carboniferous Age. Some of them were 20 feet or more high and 10 or 12 inches in diameter. Besides these Cryptogams there were also Fungi; but, as already stated, no remains of Mosses from the rocks of the age are known. In the ideal view of a Carboniferous landscape, Fig. 220, page 124, the broken trunk to the right is a Sigillaria. The landscape, to be quite true to nature, should have been made up largely of Sigillarice, Calamites, and Lepidodendra, with few tree-ferns. The Stigmarise should have been mostly con- cealed beneath the water or soil, or in the submerged mass of the floating islands. II. Phenogams, or Flowering Plants, Order of Gymnosperms. 1. Conifers. Trunks of trees, Coniferous in character, and related especially to the Araucanian pines, are not uncommon. 2. Fruits. Besides the leaves, stems, and trunks already alluded to, there are various nut-like fruits found in the Car- boniferous strata. One is represented in Fig. 226 (page 125), the figure to the left being that of the shell, and the other that of the nut which it contained. Some of them are two inches in length. The most of them were probably the fruit of Conifers. It is seen from the above that 1. The vegetation of the Carboniferous age consisted very largely of Cryptogams, or flowerless plants. 128 PALEOZOIC TIME. 2. The flowering plants, or Phenogams, associated with the flowerless vegetation, were of the order of Gymnosperms, whose flowers are imperfect and inconspicuous. 3. While, therefore, there was abundant and beautiful fo- liage (for no foliage exceeds in beauty that of Ferns), the vegetation was nearly flowerless. 4. The characteristic Cryptogams were not only of the highest group of that division of plants, but in general they exceeded in size and perfection the species of the present day, many being forest-trees. 2. Animals. 1. Radiates. Among Radiates, species of Crinoids were especially numerous in the Subcarboniferous period. Figs, 227, 228, 229 represent some of the species. The radiating arms are perfect in Fig. 227, but wanting in 228. Fig. 229 is a species of the genus Pentremites (named from the Greek 7rei/T, five, alluding to the five-sided form of the fossil). The Pentremites had a stem made of calcareous disks, like other Crinoids, but no long radiating arms at top. Fig. 230 presents an upper view of a very common Coral of the same period : it has a columnar appearance in a side view. * 2. Mollusks. The tribe of Bryozoans contained the singu- lar screw-shaped (or auger-shaped) Coral shown in Fig. 231, and named Archimedes (referring to Archimedes's screw). It is made up of minute cells that open over the lower surface ; each of the cells, when alive, contained a minute Bryozoum (page 57). These fossils are common in some of the Subcar- boniferous limestone strata. Brachiopods were the most abundant of Mollusks through the Carboniferous age, and especially species of the genera Spirifer and Productus. Figs. 232 to 235 are of species from the American Coal-measures: Fig. 234, a Spirifer ; Fig. 233, a Productus ; Fig. 232, a Chonetes ; Fig. 235, an Athyris, oc- curring also in Europe. Fig. 236 represents one of the Gas- CARBONIFEROUS AGE. 129 teropods of the Coal-measures. Fig. 237 is a Pupa, the earli- est yet found of land-snails : it is from the Coal-measures of Pigs. 227-237. 231 RADIATES : Fig. 227, Zeaerinus elegans ; 228, Aetinocrinus proboscidialis ; 229, Pentre- mites pyriformis ; 230, Lithostrotion Canadense. MOLLUSKS : Fig. 231, Archimedes reversa ; 232, Chonetes mesoloba ; 233, Productus Nebrascensis ; 234, Spirifer cameratus ; 235, Athyris subtilita ; 236, Pleurotomaria tabulata ; 237, Pupa vetusta. Nova Scotia ; others have been found in Illinois. The order of Cephalopods contained but few and small species of the old tribe of Orthocerata, but many of the Ammonite-like GrO- niatites. 6* I 130 PALEOZOIC TIME. 3. Articulates. Among Articulates, Crustaceans appeared under a new form, much like that of modern shrimps, and Trilobites were of rare occurrence. Figs. 238-240. sa. SPIDERS : Fig. 238, Arthrolycosa antiquus ; 239, Eoscorpius carbonarius. INSECT : Fig. 240, Miainia Bronsoni. Besides Insects (Fig. 240), there were also Myriapods, true Spiders (Fig. 238), and Scorpions (Fig. 239) ; the figures are of Illinois species. The Insects include May-flies (Neurop- ters), Locusts and Cockroaches (or Orthopterous insects), and Beetles (or Coleopters). 4. Vertebrates. Fishes were numerous, both of the orders of Ganoids and Selachians. All the Ganoids were of the an- CARBONIFEROUS AGE. 131 cient type, having the tail vertebrated (or heterocercal), as in Fig. 241, representing a Permian species of Palceoniscus. Many of the Selachians, or Sharks, were of great size, as shown by the fin-spines. Fig. 242 represents a small portion of one of these spines, natural size, from the Subcarboniferous beds of Europe. One of the largest specimens of the same species thus far found had a length of 14J inches, and when entire it must have been full 18 inches long. Figs. 241, 242. Fig. 241, Palseoniscus Freieslebeni (x); 242, Part of a spine of Ctenacanthus major. The first traces of Eeptiles yet known occur in the Subcar- boniferous beds of Pottsville, Pennsylvania. Fig. 243 is a reduced sketch of a slab containing tracks of the species, and also an impression left by the tail of the ani- mal. The tracks of the fore-feet, as described by Dr. Lea, are 5-fingered and 4 inches broad, and 'those of the hind feet 4-fingered and nearly of the same size ; while the stride indi- cated was 13 inches. Fig. 244 represents a skeleton of an Amphibian from the Ohio Coal-measures, found by Newberry ; and Fig. 245 a vertebra of a swimming Saurian probably re- 132 PALEOZOIC TIME. lated to the Enaliosaurs, or Sea-Saurians, of the Mesozoic (see page 174), discovered by Marsh in the Coal-measures of Nova Pigs. 243-245. Fig. 243, Tracks of Sauropus priinsevus (x |); 244, Raniceps Lyellii ; 245, a. Vertebra of Eosaurus Acadianus. Scotia. This vertebra is concave on both surfaces, as shown in the section in Fig. 245 a, and in this respect resembles those of fishes. The Enaliosaurs had paddles like Whales. . CARBONIFEROUS AGE. 133 These Enaliosaurs, or swimming Eeptiles, are the highest species of animal yet discovered in rocks of the Carboniferous period. In the Permian period there were still higher Eep- tiles, somewhat Crocodile-like, called Thecodonts (because the teeth are set in sockets, from the Greek Qr\icT), case, and oSovs, tooth). But these also had the fish-like characteristic of doubly-concave vertebrae. 5. General Observations. 1. Formation of Coal, and origin of the Coal-measures. 7. Origin of the Coal. The vegetable origin of coal is proved by the following facts : 1. Trunks of trees, retaining still the original form and part of the structure of the wood, have been found changed to mineral coal, both in the Carboniferous strata and in more modern formations, showing that the change may and does take place. 2. Beds of peat, a result of vegetable growth and accumu- lation, exist in modern marshes ; and in some cases they are altered below to an imperfect coal. (See page 265, on the formation of peat.) 3. Eemains of plants, their leaves, branches, and stems or trunks, abound in the Coal-measures ; trunks sometimes ex- tend upward from a coal-bed into and through some of the overlying beds of rock ; roots or stems abound in the under- clays. 4. The hardest anthracite contains throughout its mass vegetable tissues. Professor Bailey examined with a high magnifying power several pieces of anthracite burnt at one end, like Fig. 246, taking fragments from the junction of the white and black portion, and detected readily the tissues. Fig. 247 represents the ducts, as they appeared in one case under his microscope ; and Fig. 247 a part of the same, more magnified. Fig. 248 shows the appearance of the spores of Lycopods (Lepidodendrids) much magnified ; they are com- mon in coal. 134 PALEOZOIC TIME. 2. Decomposition of Vegetable Material. The Mineral Coal of the Coal-measures consists (impurities excluded) of 77 to 97 per cent of carbon along with 2 to 6 of hydrogen and 2 to 15 of oxygen ; and woody material, whether of Conifers, Ferns, Lycopods, or Equiseta, consists of about 50 per cent of car- bon, 6 of hydrogen, and 44 of oxygen. To change the wood Figs. 246 -247 a. 247 n Fig. 248. Vegetable tissues in Anthracite. or vegetable material to coal, it is necessary to get rid of part of the oxygen and hydrogen. Vegetable matter decomposing in the open air like wood burnt in an open fire passes, carbon and all, into gaseous combinations, and little or no carbon is left behind. But when it is decomposed slowly under water, or by a half- smothered fire, only part of the carbon is lost in gaseous combinations, the rest re- maining in combination with a portion of the hydrogen Spores and part of a Sporangium in bitumi- n __ _ j _ ji J nous coal of Ohio (x 70). oxygen as coal, mineral coal in the former case, and charcoal in the latter. The actual loss, by weight, in the transformation into bitu- CARBONIFEROUS AGE. 135 minous coal, is at least three fifths of the wood, and in that into anthracite, three fourths. Adding to this loss that from com- pression, by which the material is brought to the density of mineral coal, the whole reduction in bulk is not less than to one fifth for the former, and to one eighth for the latter. In other words, it would take 5 feet of vegetable matters to make 1 of bituminous coal, and 8 feet to make 1 of anthracite. 8. Impurities in Coal. The coal thus formed would have de- rived some silica and other earthy ingredients from the wood itself, and alumina from the Lepidodendrids, this earth exist- ing in the ash of modern Lycopods. By this means the best coal received the earthy impurities which give rise to the ashes and slag formed in a hot fire; while the poorer coals contain clay or earthy material carried over the marshes by the waters or winds. 4. Accumulation and Formation of Coal-beds. The origin of coal-beds was, then, as follows : The plants of the great marshes and shallow lakes of the Coal era, the latter with their floating islands of vegetation, continued growing for a long period, dropping annually their leaves, and from time to time decaying stems or branches, until a thick accumulation of vegetable remains was formed, probably 5 feet in thick- ness for a one-foot bed of bituminous coal. The bed of ma- terial thus prepared over the vast wet areas of the continent early commenced to undergo at bottom that slow decomposi- tion the final result of which is mineral coal. But, as the coal-beds alternate with sandstones, shales, conglomerates, and limestones, the long period of verdure was followed by another of overflowing waters, and generally, in the case of the region of the Interior basin of North America, oceanic waters, as the fossils prove, which carried sands, pebbles, or earth, over the old marsh, till scores or hundreds of feet in depth of such deposits had been made. Thus the bed of vegetable material was buried ; and under this condition the process of decomposition and change to mineral coal went forward to its completion ; it had the smothering influence of 136 PALEOZOIC TIME. the burial, as well as the presence of water, to favor the pro- cess. 5. Climate of the Age. The wide distribution of the coal regions over the globe, from the tropics to remote Arctic lands, and the general similarity of the vegetable remains in the coal-beds of these distant zones, prove that there was a general uniformity of climate over the globe in the Carbon- iferous age, or at least that the climate was nowhere colder than warm-temperate. Besides, corals and shells existed dur- ing the Subcarboniferous period in Europe, the United States, and the Arctic within 20 of the north pole, and so profusely as to form thick limestones out of their accumulations ; and some Arctic species are identical with those of Europe and America. The ocean's waters, even in the far north, were, therefore, warm compared with those of the modern temper- ate zone, and probably quite as warm as the coral-reef seas of the present age, which lie mostly between the parallels of 28 either side of the equator. 6. Atmosphere. The atmosphere was especially adapted for the age in other respects. It contained a larger amount than now of carbonic-acid gas, the gas which promotes (if not in excess) the growth of vegetation. Plants derive their carbon mainly from the carbonic acid of the atmosphere ; and hence the mineral coal of the world is approximately a measure of the amount of carbonic acid the atmosphere in the Carboni^ erous era lost. The growth of the flora of that age was a means of purifying the atmosphere so as to fit it for the higher terrestrial life that was afterward to possess the world. Again, the atmosphere was more moist than now. This follows from the greater heat of the climate and the greater extent as well as higher temperature of the oceans. The con- tinents, although large during the intervals of verdure com- pared with the areas above the ocean in the Devonian or Si- lurian, were still small and the land low. It must, therefore, have been an era of prevailing clouds and mists. A moist climate would not, however, have been universal, since even CARBONIFEROUS AGE. 137 the ocean has now its great areas of drought depending on the courses of the winds. America is now the moist forest- conti- nent of the globe ; and the great extent of the coal-fields of its northern half proves that it bore the same character in the Carboniferous age. 2. Geography. 7. Appalachian and Rocky Mountains not made. On page 114 it is stated that the continents in this age were low, with few mountains. The non-existence of the Appalachians of Pennsylvania and Virginia is proved by the fact that the rocks of these mountains are to a considerable extent Carboniferous rocks; partly marine rocks, indicat- ing that the sea then spread over the region ; partly coal-beds, each bed evidence that a great fresh- water marsh, flat as all marshes are, for a long while occupied the region of the pres- ent mountains. There is the same evidence that the mass of the Rocky Mountains had not been lifted; for marine Carboniferous rocks constitute a large part of these mountains, many beds containing remains of the life of the Carboniferous seas that covered that part of North America. Only islands, or archi- pelagoes of islands, made by some Arcliean and perhaps also Paleozoic ridges, existed in the midst of the widespread western waters. 2. Condition in the Subcarboniferous Period. Through the first period of this age the Subcarboniferous the continent was almost as extensively beneath the sea as in the Devonian age. This, again, is shown by the nature and extent of the Subcarboniferous rocks, the great crinoidal limestones. The shallow continental seas were profusely planted with Crinoids amid clumps of Corals. Brachiopods were here and there in great abundance, many lying together in beds as oys- ters in an oyster-bed; other Mollusks, both Lamellibranchs and Gasteropods, were also numerous ; Trilobites were few ; Goniatites and Nautili, along with Ganoid Fishes and Sharks, were the voracious life of the seas, and Amphibian reptiles haunted the marshes. 138 PALEOZOIC TIME. 8. Transition to the Carboniferous Period. Finally, the Sub- carboriiferous period closed, and the Carboniferous opened. But in the transition from the period of submergence to that of emergence, required to bring into existence the great marshes, a widespread bed of pebbles, gravel, and sand was accumulated by the waves dashing rudely over the surface of the rising continent; and these pebble-beds make the Mill- stone grit that marks the commencement of the Carboniferous period in a large part of Eastern North America, especially along the Appalachian region, and also in Europe. 4. Coal-plant Areas in the Carboniferous Period. Then began the epoch of the Coal-measures. The positions of the great coal areas of North America (see map, page 69) are the positions, beyond question, of the great marshes and shallow fresh-water lakes of the period. But it is probable that the number of these marshes was less than that of the coal areas. The Appalachian, Illinois, Mis- souri, Arkansas, and Texas fields may have made one vast Interior continental marsh-region, and those of Rhode Island, Nova Scotia, and New Brunswick an Eastern border marsh- region connected over Massachusetts Bay and the Bay of Fundy. There is reason, however, for believing that a low area of dry land extending from the region of Cincinnati into Tennessee (page 91) divided at least the northern portion of the Interior marsh. The Michigan marsh-region appears also to have had its dry margins, instead of coalescing with the Illinois or Ohio areas. It is not to be inferred that the marshes alone were cov- ered with verdure. The vegetation probably spread over all the dry land, though making thick deposits of vegetable re- mains only where there were marshes under dense jungles and shallow lakes with their floating islands. 5. Alternations of Condition: Changes of Level. It has been remarked that the many alternations of the coal-beds with sandstones, shales, conglomerates, and limestones (page 119), CARBONIFEROUS AGE. 139 are evidence of as many alternations of level, or at least of conditions, during the era. After the great marshes of the Continental Interior had been long under verdure, the salt waters began again to encroach upon them in consequence of a sinking of the land, and finally swept over the whole surface, destroying the terrestrial and fresh- water life of the area, that is, the terrestrial and fresh- water Plants, Mollusks, Insects, and Eeptiles, but distributing at the same time the new life of the salt waters. Then, after another long period, one perhaps of many oscillations in the water-level, in which sedimentary beds in many alternations were formed, the continent again rose to aerial life, and the marshes and shallow lakes were luxuriant anew with the Carboniferous vegetation. Thus the O sea prevailed at intervals intervals of long duration - through the era even of the Coal-measures ; for the associated sedimentary beds, as has been stated, are at least fifty times as thick as the coal-beds. In the Nova Scotia Coal area, the waters which came in over the coal-beds were the brackish or fresh waters of a great estuary, that at the mouth of the St. Lawrence River of the Carboniferous period. These oscillations continued until 3,000 to 4,000 feet of strata were formed in Pennsylvania, and over .14,000 in Nova Scotia. The Carboniferous period was, therefore, ever varying in its geography. A map of its condition when the great coal- beds were accumulating would have its eastern coast-line not far inside of the present, and in the region of Nova Scotia and New England even outside of the present ; for there must have been a sea-barrier in order that the deposits in the for- mer region should have been of brackish or fresh-water origin. The southern coast-line would pass through central Carolina, Georgia, Alabama, and Northern Mississippi, then west of the Mississippi, around Arkansas and the bordering counties of Texas ; thence it would stretch northward, bounding a sea covering a large part of the Rocky-Mountain region, for the Coal period was, in that part of the continent, mainly a 140 PALEOZOIC TIME. time of limestone-making. On the contrary, in a map repre- senting it during the succeeding times of submergence, the coast-line would run through Southeastern New England, then near the southern boundary of New York State, then north- westward around Michigan, then southward again to Northern Illinois, and then westward and northwestward to the Upper Missouri region, or the Eocky Mountain sea. Through these conditions, as the extremes, the continent passed several times in the course of the Carboniferous period. 6. Condition in the Permian Period. Finally, in the Permian period, the Appalachian region, and the Interior region east of a north-and-south line running through Missouri, appear to have been mainly above the ocean ; for the Permian beds are mostly confined to the meridians of Kansas and the remoter West. GENERAL OBSERVATIONS ON THE PALEOZOIC. 1. Rocks, 7. Maximum thickness. The maximum thick- ness of the rocks of the Silurian age in North America is *at least 25,000 feet ; of the Devonian, about 14,400 feet ; and of the Carboniferous age, about 16,000 feet. 2. Diversities of the different Continental regions as to kinds of rocks. The Paleozoic rocks of the Appalachian region are mainly sandstones, shales, and conglomerates ; only about one fourth in thickness of the whole consists of limestone. The rocks of the Interior Continental are mostly limestone, full two thirds being of this nature. The difference of these two regions, in this particular, will be appreciated on comparing the following general section of the strata of the Interior with the section, on page 67, of the rocks of New York, New York State lying on the inner border of the Appalachian region. The Lower Silurian beds in the Mississippi basin, as the section shows, consist mainly of limestones ; so also the Upper Silurian, Devonian, and Sub- carboniferous formations ; and the Carboniferous of the region GENERAL OBSERVATIONS. 141 contains more limestone than that of the East. In the Devo- nian of the Interior the Hamilton is represented by a lime- stone in parts of Michigan, Ohio, Canada West, and Illinois, to Iowa, and besides this there is only a black shale, one to three or four hundred feet thick. In the Eastern-border region, about the Gulf of St. Law- rence, there is a great predominance of limestones in the Pig. 249. Permian Carboniferous Subcarboniferous Chemung ... ( Hamilton ( Corniferous Niagara j Cincinnati j Trenton j Canadian j Potsdam J Permian. Coal Measures. Coal Conglomerate. Subcarboniferous limestone. Subcarboniferous sandstone. Black shale. Cliff limestone. Blue limestone and shale. Trenton limestone ; Galena limestone ; Black River limestone. Lower Magnesian limestone (= Calciferous). Potsdam sandstone. Section of the Paleozoic rocks in the Mississippi basin. formations. They prove the existence in that region of an Atlantic-border basin similar in some respects to the basin of the Interior, the two being separated by the Green Moun- tains, that is, the northern part of the Appalachian region. 3. Diversities of the Appalachian and Interior-Continental regions as to the thickness of the rocks. In the Appalachian region the maximum thickness of the Paleozoic rocks is about 50,000 feet. But this thickness is not observed at any one locality, it being obtained by adding together the greatest thicknesses of the several formations wherever observed. The greatest actual thickness at anyone place in Pennsylvania is about 40,000 feet, or over seven miles. 142 PALEOZOIC TIME. In the central portions of the Interior-Continental region the thickness varies from 3,500 feet (and still less on the northern border) to 6,000 feet ; and it is, therefore, from one sixth to one tenth that in the Appalachian region. 4. Origin of the deposits. The material of the fragmental rocks, or those of sand, clay, mud, pebbles (the sandstones, shales, earthy sandstones and conglomerates), was "made (1) by the wear of pre-existing rocks under the action of water ; (2) by disintegration produced by partial decomposition ; and (3) by disaggregation from expansion and contraction due to daily and annual changes of temperature. The water was mainly that of the ocean, and the power was that of its waves and currents. But the water from the rains aided in the wear, although there were no large rivers ; and, through the carbonic acid it took up from the atmosphere, it was a great agent in the disintegration of exposed rocks, feldspar, the most common ingredient in crystalline rocks and also nearly all iron-bearing minerals, yielding more or less easily under the action. The material of the coarser rocks may have accumulated where the waves were dashing against a beach or an exposed sand-reef, or else where currents were in rapid movement over the bottom; for accumulations of pebbles and coarse sand are now made under these circumstances. The material of the earthy sandstones may have been the mud or earthy sands forming the bottom of shallow seas. The fine clayey or earthy deposits must have been made in either sheltered bays or interior seas, in which the waves were light, and therefore fitted to produce by their gentle attrition the finest of mud ; or else in the deeper off-shore waters, where the finer detritus of the shores is liable to be borne by the currents. Accumulations of any degree of thickness may be made in shallow waters, provided the region is undergoing very slow subsidence ; for in this way the depth of the waters may be kept sufficient to allow of constantly increasing depositions. Thus, by a slow subsidence of 1,000 feet, deposits 1,000 feet GENERAL OBSERVATIONS. 143 thick may be produced, and the depth of water at no time exceed 20 feet. The occurrence of ripple-inarks, mud-cracks, or rain-drop impressions in many beds of most of the forma- tions proves that the layers so marked were successively near the surface, and therefore that there must have been a grad- ual sinking of the bottom as the beds were formed. The limestones of the Paleozoic were probably made, in every case, out of organic remains, either Shells, Corals, Cri- noids, etc., or the minute Khizopods, which are known to have formed, to a large extent, the chalk-beds of Europe. Shells, Corals, and Crinoids must be ground up by the waves to form fine-grained rocks ; while the shells of Ehizopods are so minute as to be already fine grains, and may become compact rocks by simple consolidation. The hornstone in the limestones, as remarked on page 108, may be wholly of organic origin. 2. Time-Ratios. Judging from the maximum thickness of the rocks of the several Paleozoic ages in North America, and allowing that five feet of fragmental rocks may accumulate in the time required for one foot of limestone, the relative lengths of the Silurian, Devonian, and Carboniferous ages were not far from 4 : 1 : 1, and the Lower Silurian era was four times as long as the Upper. Time moved on slowly in the earth's first beginnings. The condition of the earth in an age of Invertebrates, when all life was the life of the waters, and nothing existed above the ocean's level except it may be the humble lichen or fungus, was very inferior to that of the Carboniferous, when the con- tinents had their forests, the waters their fishes, and the marshes their reptiles. Yet the length of time through which the earth was groping under the first-mentioned condition was vastly longer than under the last. Such is time in the view of the infinite Creator. 3. Geography. 7. Close of Archcean time. The map on page 73 shows approximately the outline of the dry land of North America at the close of the Archaean. The only mountains 144 PALEOZOIC TIME. were Archsean mountains, the principal of which were the Laurentian of Canada, the Adirondacks of Northern New York, the Highlands of New Jersey and Dutchess County of New York, the Blue Kidge farther to the southwest, and the Wind- River and other eastern ridges of the Eocky Mountain region. We qannot judge of the height of these mountains then from what we now see, after all the ages of Geology have passed over them, for the elements and running water have never ceased action since the time of their uplift, and the amount of loss by degradation must have been very great. 2. General Progress through Paleozoic time. The increase of dry land during the Paleozoic has been shown (pages 99, 113) to have taken place mainly along the borders of the Archsean, so that the original area was thus gradually extending. This increase is well marked from north to south across New York. At the close of the Lower Silurian the shore-line was not far from the present position of the Mohawk, indicating but a slight extension of the dry land in the course of this very long era; when the Upper Silurian ended, the shore-line probably extended along a score of miles or so south of the Mohawk. When the Devonian ended and the Carboniferous age was about opening, the coast-line was just north of the Pennsylvania boundary. The progress southward was at an equal rate in Wisconsin, where there is an isolated Archaean region like that of North- ern New York. In the intermediate district of Michigan the coast made a deep northern bend through the Silurian and Devonian. In the Carboniferous the same great Michigan bay existed during the intervals of submergence ; but it was changed to a Michigan marsh or fresh-water lake, filled with Coal-measure vegetation, during the intervening portions of the Carboniferous period ; and, at the same times, as explained on page 139, the continent east of the western meridian of Missouri had nearly its present extent, though not its moun- tains or its rivers. 3. Regions of rock-making, and their differences. The sub- GENERAL OBSERVATIONS. 145' merged part of the continent was the scene of nearly all the rock-making ; and this work probably went on over its whole wide extent. The rocks, as partially explained on page 142, varied in kind with the depth, and with the exposure to the open sea. This Interior Continental region, which was for the most of the time a great interior oceanic sea, afforded the conditions fitted for the growth of Corals and Crinoids and other clear- water species, and hence for the making of limestone reefs out of their remains ; for limestones are the principal rocks of the Interior. Yet there were oscillations in the level ; for there are abrupt transitions in the limestones, and some sand- stones and shales alternate with them. But these oscillations were not great, the whole thickness of the rocks, as stated 011 page 142, being small The Appalachian region, on the contrary, presented the conditions required for fragmental deposits. It was appar- ently a region of immense sand-reefs and mud-flats, with bays, estuaries, and extensive submerged plateaus or off-shore soundings, such as might have existed in the face of the ocean. Here the change of level was very great ; for within this region occur the seven miles of Paleozoic formations (page 141). This vast thickness indicates that while there were various upward and downward movements over this Appala- chian region through Paleozoic time, the downward move- ments exceeded the upward even by the amount just stated. These movements, moreover, were in progress from the Pots- dam period onward ; the formations of nearly every period in the series exceed 8 to 10 times the thickness they have over the Interior region. 4. Mountains of Paleozoic origin. The mountains in Eastern North America, made in the course of the Paleozoic ages, were few. Those of the region south of Lake Superior about Keweenaw Point, and to the west, probably rose during the Canadian period, the second of the Lower Silurian. The Green Mountain region became dry land after the close of the 146 PALEOZOIC TIME. Lower Silurian (page 90) ; but there is no reason to believe that it was at its present level, for the Hudson River Valley east of Hudson, and part or all of the Connecticut Valley, was beneath the ocean, and became covered by crinoidal and coral reefs and other formations during the Lower Helderberg era, and perhaps also during the early Devonian. The Devonian and other beds of the vicinity of Gaspe, and of Nova Scotia and New Brunswick, were raised into ridges before the Car- boniferous age began, mountain-making having gone forward in this Atlantic-border region after the close of the Devonian. But the larger part of the continental area remained without mountains. The Eocky chain had only some ridges as isl- ands in the seas, and the Appalachians south of New England were yet to be made. 5. Rivers ; Lakes. The depression between the New York and the Canada Archaean, dating from Archaean time, was the first indication of a future St. Lawrence channel. It con- tinued to be an arm of the sea, or deep bay, through the Si- lurian, and underwent a great amount of subsidence as it received its thick formations. After the Silurian age marine strata ceased to form, indicating thereby that the sea had re- tired ; and fresh waters, derived from the Archaean heights of Canada and New York, probably began their flow along its upper portion, and emptied into the St. Lawrence Gulf of the time not far below Montreal. . The raising of New York State out of water at the close of the Devonian suggests that from that time the Hudson Valley was a stream of fresh water. The valley itself, and its continuation north as the Champlain Valley, date from the close of the Lower Silurian, if not from the Ar- chaean. The Mississippi and its tributaries, east and west, were not in existence in the Paleozoic ages. In the intervals of Car- boniferous verdure, when the continent was emerged, the Ohio and Mississippi basin were regions of great marshes, lakes, and bayous, and not of great rivers ; for rivers could GENERAL OBSERVATIONS. 147 not exist without a head of high land to supply water and give it a flow. Over portions of Lake Superior there were extensive rock- deposits and igneous eruptions in part of the Canadian period ; and the thick accumulations show that deep subsidences were then in progress there, as also in the region of the St. Law- rence ; so that we may infer that the basin of this great lake was already in process of formation before the Lower Silurian closed. The extent and position of the great Michigan bay through the Silurian and Devonian ages and much of the Carboniferous, as mentioned on pages 99, 138, show that Lakes Erie, Huron, and Michigan were then within the limits of this bay. Whether deeper or not than other portions of the bay, is not known. Thus, Geology studies the Geography of the Paleozoic ages, and traces North America through its successive stages of growth. 4. Climate. No evidence has been found through the Paleozoic records of any marked difference of temperature between the zones. In the Carboniferous age the Arctic-seas had their Corals and Brachiopods, and the Arctic lands their forests and marshes under dense foliage, no less than those of America and Europe. The facts on this subject are stated on page 136. 5. Life. 7. Appearance and disappearance of species. With the beginning and progress of each formation in the series, new species appeared, and the old ones more or less com- pletely disappeared. Such changes in the life occurred in connection even with the minor transitions in the rock-for- mations, as in that from a bed of shale to sandstone or to limestone, and the reverse. Thus, through the ages, life and death were in concurrent progress. 2. Beginning and ending of genera, families, and higher groups. The following table of the tribe of Trilobites illustrates the progress which took place in this group and exemplifies the general fact with regard to other tribes : 148 PALEOZOIC TIME. Trilobites Paradoxides. Bathyurus Asaphus, Remopleurides ... Calymene, Ampyx, Illsenus, Acidaspis, and Ceraurus Homalonotus and Lichas. Phillipsui, Griffithides The vertical columns correspond to the Lower and Upper Silurian, the Devonian, and the Carboniferous. The left- hand column under Lower Silurian corresponds to the first, or Primordial period ; and the three columns under the Car- boniferous, to the Subcarboniferous, Carboniferous, and Per- mian periods of the age. Opposite TRILOBITES, the black area shows that the tribe began with the beginning of the Paleo- zoic and continued nearly to its end. Next there is the name of a genus which existed only in the Primordial period, it having then many species, but none afterward ; with it there were other genera which had species also in the later part of the Lower Silurian. Then there is a genus, Bathyurus, which continued from the Primordial through the Lower Silurian. Then, others confined to the rest of the Lower Silurian ; others that passed into the Upper Silurian, then to become extinct ; others that continued into the Devonian; and two genera confined to the Carboniferous. In a similar manner the genera and families of Brachiopods began at different periods or epochs, and continued on for a while, to become, in general, extinct. Many genera ended in the course of the Paleozoic and at its close ; only a few con- tinued into later periods. GENERAL OBSERVATIONS. 149 3. Special Paleozoic peculiarities of the Life. The following facts show in what respects the life of the Paleozoic ages was peculiarly ancient : a. Not only are the species all extinct, but almost every genus. Fifteen or sixteen of the genera which existed in the course of the Paleozoic have living species ; and all these are Molluscan. b. Among Eadiates, the Polyps were largely of the tribe of Cyathophylloid corals, which is almost exclusively ancient or Paleozoic. The Echinoderms were mostly Crinoids, and these were in great profusion. Crinoids were far less abundant, and of different genera, in the Mesozoic ; and now, few exist. c. Among Mollusks, Brachiopods were exceedingly abun- dant : their fossil shells far outweigh those of all other Mol- lusks. But in the Mesozoic they were much less numerous than other Mollusks; and at the present time the group is nearly extinct. The Cephalopods were represented very largely by Orthocerata, but few species of which existed in the early Mesozoic, and none afterward. d. Among Articulates, Trilobites were the most common Crustaceans, a group exclusively Paleozoic. e. Among Vertebrates, the Devonian Fishes were either Ganoids, Placoderms, or Selachians, and the Ganoids had verte- Irated tails. Of this kind of Ganoids, but few species lived in the first period of the Mesozoic ; and the whole group of Ganoids is now nearly extinct. Of the Selachians, a large proportion were Cestracionts, a tribe common in the Meso- zoic, but now nearly extinct. /. Among terrestrial Plants, there were Lepidodendrids, Sigillarids, Catamites in great profusion, mating, with Conifers and Ferns, the forests and jungles of the Carboniferous and later Devonian : no Lepidodendrid or Sigillarid existed after- ward, and the Calamites ended in the Mesozoic. Thus, the Paleozoic or ancient aspect of the animal life was produced through the great predominance of Brachiopods, Cri- noids, Cyathophylloid Corals, Orthocerata, Trilobites, and verte- 150 PALEOZOIC TIME. brated-tailed Ganoids ; and that of the plants over the land, through the Lepidodendrids, Sigillarids, and Calamites, along with the Ferns and Conifers. In addition to this should be mentioned the absence of Angiosperms and Palms among Plants ; the absence of Teliost Fishes, and of Birds and Mam- mals, among Vertebrates ; and of nearly all modern tribes of genera among Radiates, Mollusks, and Articulates. 4. Mesozoic and Modern types begun in Paleozoic time. The principal Mesozoic type which began in the Paleozoic was the Reptilian. But besides these Reptiles there were the first of the Decapod Crustaceans ; the first of Oysters ; the first of the great tribe of Ammonites, the Goniatites being of this tribe ; the first of Insects, Spiders and Centipedes. The type of In- sects, or terrestrial Articulates, belongs eminently to modern time ; for it probably has now its fullest display. Thus, while .the Paleozoic ages were progressing, and the types peculiar to them were passing through their time of greatest expansion in numbers and perfection of structure, there were other types introduced which were to have their culmination in a future age. ...*-. DISTURBANCES CLOSING PALEOZOIC TIME. L General quiet of the Paleozoic Ages. The long ages of the Paleozoic passed with but few and comparatively small disturbances of the strata of Eastern North America. There were some early permanent uplifts in the Lake Superior region, during the Lower Silurian; again, after the Lower Silurian, the Green Mountains were made ; and again, after the close of the Devonian, there were disturbances and upturn- ings in Eastern New Brunswick, part of Nova Scotia, and East- ern Canada by Gaspe near St. Lawrence Bay. Besides these changes there was, through the ages, a gradual increase on the north in the amount of dry land ; and through parts of all the periods, over a large part of the continent, slow oscil- lations were in progress, varying the water-level and favoring APPALACHIAN REVOLUTION. 151 the increasing thickness of the rocks, and their successive variations as to kind and extent. But these movements of the earth's crust were exceedingly slow, probably less than a foot a century. There may have been many occasional quakings of the earth, even exceeding the heaviest of modern earthquakes. There may have been at times sudden risings or sinkings of portions of the continental crust. But the condition of the strata of the interior of the continent, and of the Appalachian region south of the Green Mountains, indicates that general quiet prevailed through the long Paleo- zoic ages. 2. The Appalachian the region of greatest change of level through the Paleozoic. The region of greatest movement dur- ing these ages was the Appalachian. For it has been shown that the oscillations which there took place resulted in sub- sidences of one or more thousand feet with nearly every period of the Paleozoic. In the Green Mountain portion the oscilla- tions ceased after the close of the Lower Silurian era ; but not until the subsidence there had reached probably 20,000 feet : and in Pennsylvania and Virginia they continued through a large part of the Carboniferous age, until the sinking amounted to 35,000 or 40,000 feet. But this sinking was quiet in its progress, as is proved by the regularity in the series of strata. The thickness of the coal-beds indicates that the coal-plant marshes were long undisturbed, and therefore that long periods passed without appreciable movement. 3. Approach of the epoch of Appalachian revolution. The era of comparative quiet alluded to came gradually to a close as the Carboniferous age was terminating, and an epoch of upturning and mountain-making began. There are mountains to testify to this both in Europe and America. In Eastern North America the disturbances affected Nova Scotia and the coal area of Ehode Island and Southeastern Massachusetts ; and, with far grander results, the Appalachian region and Atlantic border from Southern New York to Ala- bama. The Appalachian mountains are a part of the result, 152 CLOSE OF PALEOZOIC TIME. and hence the epoch is appropriately styled the epoch of the Appalachian revolution. The region in Eastern America of the deepest Paleozoic subsidence and of the thickest accumu- lation of Paleozoic rocks, that is, the Appalachian, was now the region of the profoundest disturbances and the greatest uplifts. 4. Effects of the disturbances. The following are among the effects of the disturbances along the Appalachian region and Atlantic border : 1. Strata were upraised and flexed into great folds, some of the folds a score or more of miles in span. 2. Deep fissures of the earth's crust were opened, and faults innumerable were produced, some of them of 10,000 to 20,000 feet. 3. Eocks were consolidated; and over some parts sand- stones and shales were crystallized into gneiss, mica-schist, and other related rocks, and limestone into architectural and statuary marble. 4. Bituminous coal was turned into anthracite in Penn- sylvania and Ehode Island. 5. In the end,. the Appalachian mountains were made. ; 5. Evidence of the flexures, uplifts, and metamorphism. The evidence that the rocks of the Appalachian region and Atlantic border were flexed, uplifted, faulted, and -otherwise changed from their original condition, is as follows : The Coal-measures and other Paleozoic strata, though originally spread out in horizontal beds, are now in an uplifted and flexed or folded condition ; and they are so involved to- Fig. 250. Section of the Coal-measures near Nesquehoning, Pennsylvania. gether in one system of flexures and uplifts that the whole must have been the result of one system of movements. Figs. 250 - 253 illustrate this. APPALACHIAN REVOLUTION. Fig. 250 shows the condition of the Anthracite coal-beds of Mauch Chunk in Pennsylvania. Some of the upturned Fig. 251. Section on the Schuylkill, Pennsylvania ; P., Pottsville on the Coal-measures ; 2, Calciferous formation ; 3, Trenton ; 4, Hudson River ; 5, Oneida and Niagara ; 7, Lower Helderberg ; 8, 10, 11, Devonian ; 12, 13, Subcarboniferous ; 14, Carboniferous, or Coal-measures. beds, as is seen, stand nearly vertical. Fig. 251 is from another locality near Pottsville in the same State. The coal- beds are the upper ones numbered 14 ; the rest are the beds of the Upper and Lower Silurian (2 to 7) ; the Devonian (8, 10, 11) and Subcarboniferous (12, 13). Fig. 252 was taken from Fig. 252. Section from the Great North to the Little North Mountain through Bore Springs, Virginia ; t, t, position of thermal springs ; 11, Calciferous formation ; in, Trenton ; iv, Hudson River; v, Oneida; vi, Clinton and Lower Helderberg, vu, Oriskany Sandstone and Cauda-Galli Grit. the vicinity of Bore Springs, in Virginia, and includes Silurian and Devonian beds : it shows well the folded character of the Fig. 253. m Section of the Paleozoic formations of the Appalachians in Southern Virginia, between Walker's Mt. and the Peak Hills (near Peak Creek Valley) : F, fault ; a, Lower Silurian limestone ; &, Upper Silurian ; c, Devonian ; d, Subcarboniferous, with coal-beds. rocks. Fig. 253 represents one of the great faults in South- ern Virginia (between Walker's Mountain and Peak Hills) ; 154 CLOSE OF PALEOZOIC TIME. the break is at F, and the rocks on the left were shoved up along the sloping fracture until a Lower Silurian lime- stone (a) was on a level with the Subcarboniferous formation (cQ, a fault of more than 10,000 feet. Such examples are in great numbers throughout the Appalachians. In many of the transverse valleys the curves may be traced for scores of miles. As shown in the above sections (Figs. 250-253), the folds, instead of remaining in regular rounded ridges with even synclinal valleys between, such as the flexing of the strata might make, have been to a great extent worn away, or mod- elled into new ridges and valleys, by the action of waters during subsequent time ; and often what was the top of a fold is now the bottom of a valley, because the folds would be most broken where most abruptly bent, that is, along the axes of upward flexure, and hence would be most liable in these parts to be cut away or gorged out by any denuding causes. The figures on page 43 illustrate still further the condition of folded strata before and after denudation. Some of the Appalachian folds were probably 20,000 feet in heigtit above the present level of the ocean, or would have had this height if they had remained unbroken, while in fact the loftiest summits now are less than 5,000 feet, and few exceed 3,000 feet. Over New England there are similar flexures. Those of the Rhode Island coal-formation are very abrupt, and full of faults, the coal-beds being much broken and displaced. 6. General truths with regard to the results. The follow- ing are some of the general truths connected with the uplifts and metamorphism : 1. The courses of the flexures and of the outcrops or strike, and those of the great faults, are approximately north- east, or parallel to the Atlantic border. There is a bend eastward in Pennsylvania corresponding with the eastward bend of the southern coast of New England, and then a change to the northward in New England. APPALACHIAN REVOLUTION. 155 2. The folds have their steepest slope toward the northwest, or away from the ocean. If Fig. 41 (page 43) represent one of the folds, the left would be the ocean side, or that to the southeast, and the right the landward side, or that to the northwest. 3. The flexures are most numerous and most crowded on that side of the Appalachian region which is toward the ocean, and diminish westward. There is seldom, however, a gradual dying out westward, the region of disturbance being often bounded on the west by one or more of the great fractures and faults, as in Eastern Tennessee and along the valley of the Hudson. 4. The consolidation and metamorphism of the strata are more extensive and complete to the eastward (or toward the ocean) than to the westward. 5. The change of bituminous coal to anthracite, by the expulsion of volatile ingredients, was most complete where the disturbances were greatest, that is, in the more eastern portions of the coal areas. The anthracite region of Penn- sylvania (see map, p. 116) owes its broken character partly to the uplifts and partly to denudation. To the westward the coal is first semi-bituminous, and then, as at Pittsburg, true bituminous. In Ehode Island, where the associated rocks are partly true metamorphic or crystalline rocks and the disturbances are very great, the coal is an extremely hard anthracite, and in some places is altered to graphite, an effect which may be produced in ordinary coal by the heat of a furnace. 7. Conclusions, These facts lead to the following conclu- sions : 1. The movement producing these vast results was due to lateral pressure, the folding having taken place just as it might in paper or cloth under a lateral or pushing movement. 2. The pressure was exerted at right angles to the courses of the folds, as is the case when paper is folded in the manner mentioned. 156 CLOSE OF PALEOZOIC TIME. 3. The pressure was exerted from the ocean side of the Appalachians ; for the results in foldings and metamorphism are most marked toward the ocean. 4. The force was vast in amount. 5. The force was slow in action and long continued, and not abrupt or paroxysmal as when a wave or series of waves is thrown up by an earthquake shock on the surface of an ocean. For the strata were not reduced by it to a state of chaos, but retain their stratification, and show comparatively little confusion, even in the regions of greatest disturbance and alteration. 6. The action of the force was attended by the production of heat. For without some heat above the ordinary tempera- ture, it is not possible to account for the consolidation and crystallization of the rocks. 7. The history of the Appalachian Mountains extends through all the geological ages from the Archaean onward. During the Silurian, Devonian, and Carboniferous ages the formations were accumulating to a great thickness, while a slow subsidence was in progress. When the Carboniferous age was closing, and the subsidence had reached a depth of several miles, there were other movements, producing flexures of the strata, uplifts, faults, consolidation, and metamorphism, and ending in the making of the mountains. And finally, during these upliftings, moving waters commenced the work of denudation, which has been continued to the present time. 8. Disturbances on other continents. The amount of con- temporaneous mountain-making over the globe at this epoch has not yet been clearly made out. Enough is known to ren- der it probable that the Ural Mountains, with their veins of gold and platinum, were made at the same time with the Ap- palachians, and that uplifts and metamorphism also occurred in other parts of Europe, and in Great Britain. Murchison states that the close of the Carboniferous period was specially marked by disturbances and uplifts ; that it was then " that the coal strata and their antecedent formations were very MESOZOIC TIME. 157 generally broken up, and thrown, by grand upheavals, into separate basins, which were fractured by numberless power- ful dislocations." The epoch of the Appalachian revolution was, then, a grand epoch for the world. The extermination of life which took place at the time was one of the most extensive in all geological history, and must have been a consequence of the great physical changes progressing over the earth's surface. But it cannot be affirmed that the extermination was univer- sal, although no fossils of the Carboniferous formation occur in later rocks ; for these strata, as they are confined to portions of the continental seas, testify only as to changes and de- structions throughout those seas, and not respecting the life existing elsewhere. III. MESOZOIC TIME. 1. Ages. Mesozoic or mediaeval time, in Geological his- tory, comprises but one age, the EEPTILIAN. In the course of it the class of Eeptiles passed its culmination ; that is, its species increased in numbers, size, and diversity of forms, until they vastly exceeded in each of these respects the Hep- tiles of either earlier or later time. 2. Area of progress in rock-making. The area of rock- making in North America, during Mesozoic time, was some- what different from what it was in Paleozoic. Then, nearly the whole continent, outside of the northern Archaean area, was receiving its successive formations ; and the three great regions were the Eastern border, the Appalachian, and the Interior Continental. By the close of Paleozoic time the Appalachian region and the Interior east of the Mississippi, excepting its southern portion, had become part of the dry land of the continent, as is shown by the absence of marine strata of later date. The great areas of progress were conse- 158 MESOZOIC TIME. REPTILIAN AGE. quently changed, and became (1) the Atlantic border, (2) the Gulf border, and (3) the Western Interior, or region west of the Mississippi. In other words, the continent, from the Mesozoic onward, until the close of the Tertiary period in the Cenozoic, was receiving its new marine formations along its borders, and in extensive areas over the part of the Interior region embraced by the Summit region and slopes of the Rocky Mountains. These three regions are continuous with one another, the Atlantic connecting with the Gulf border region on the south, and the Gulf border region passing northwestward into the Western Interior or Rocky Mountain region and Pacific border. In Europe no analogous change can be distinguished ; for the continent was, from the first, an archipelago, and it con- tinued to bear this geographical character, though with an increasing prevalence of dry land, until the Cenozoic era had half passed. Western England then stood as three or four islands above the sea (the area marked as covered by Paleo- zoic rocks on the map, page 118) ; and the area of future rock- making was mainly confined to the intervals between these islands and to the submerged area on the east and southeast. It is probable that this area and a portion of Northeastern France were, geologically, part of a large German-Ocean basin. REPTILIAN AGE. Periods. The Reptilian Age includes three periods : 7. Tn'assic : named from the Latin tria, three, in allusion to the fact that the rocks of the period in Germany consist of three separate groups of strata. This is a local subdivision, not characterizing the rocks in Britain or in most other parts of Europe. 2. Jurassic: named from the Jura Mountains, situated on the eastern border of France, between France and Switzerland, where rocks of the period occur. TRIASSIC AND JURASSIC PERIODS. 159 3. Cretaceous : named from the Latin creta, chalk, the chalk- beds of Britain and Europe being included in the Cretaceous formation. 1. Triassic and Jurassic Periods. I. Rocks: Kinds and Distribution. The American rocks of the Triassic period have not yet been separated from those of the Jurassic, except in the re- gion west of the Mississippi. In the Atlantic-border region these rocks occupy narrow ranges of country parallel with the Appalachian chain, fol- lowing its varying courses. One of these ranges occupies the valley of the Connecticut between Northern Massachusetts and New Haven on Long Island Sound, and runs parallel with the Green Mountains: it has a length of about 110 miles. Another the longest of them commences at the north extremity of the Palisades, on the west bank of the Hudson River, and stretches southwestward through New Jersey, Pennsylvania (here bending much to the westward, like the Appalachians of the State, as shown in the map on page 116), and reaching far into the State of Virginia. Another stretches almost in the line of the last through North Carolina. There is another along Western Nova Scotia. These, and some other smaller areas, are indicated on the map on page 69 by an oblique lining in which the lines run from the right above to the left below. The rocks are mainly sandstones and conglomerates, but include some considerable beds of shale, and in a few places impure limestone. The sandstones are generally red or brownish-red. The freestone of Portland, near Middletown in Connecticut, and of the vicinity of Newark in New Jer- sey, are from this formation. The pebbles and sand of the beds were derived mainly from metamorphic rocks alongside of the regions in which they lie ; and from some of the coarser layers large stones of granite, gneiss, and mica-schist 160 MESOZOIC TIME. REPTILIAN AGE. may be taken. The strata overlie directly, but unconform- ably, these inetamorphic rocks. Near Eichmond in Virginia and in North Carolina there are valuable beds of bituminous coal. The several ranges of this sandstone formation are remark- able for the great number of trap dikes and trap ridges inter- secting them (page 30). Mount Holyoke in Massachusetts, East and West Eocks near New Haven in Connecticut, and the Palisades on the Hudson are a few examples of these trap ridges. Trap is an igneous rock, one that was ejected in a melted state from a deep-seated source of fire, through fis- sures made by a fracturing of the earth's crust. The dikes and ridges are exceedingly numerous, and have the same gen- eral course with the sandstone ranges. They are so associated with the sandstone formation that there must have been some connection in origin between the water-made and the fire-made rocks. The proofs that the trap came up through the fissures in a melted state are abundant ; for the wall-rock of the fissures is often baked so as to be very hard, and is sometimes filled with crystallizations, as of epidote, tourma- line, garnet, hematite, etc., evidently due to the heat. West of the Mississippi, in the Western Interior region southwest of Southern Kansas, there is a sandstone formation, containing much gypsum (and hence called the gypsiferous formation), but barren of fossils, except an occasional frag- ment or trunk of fossil wood, which is regarded as Triassic. Triassic beds occur also in Colorado and New Mexico, Utah and Nevada. Along with Jurassic strata they enter into the constitution of the Elk and Wahsatch mountains, and the Sierra Nevada. These western Jurassic beds in many places contain fossils, but only rarely so the Triassic. In the vicinity of the Black Hills, in the region of the Upper Missouri, there are some beds of impure limestone con- taining marine fossils which are true Jurassic. In Europe, the Triassic rocks of Eastern France and Ger- many, east and west of the Ehine, consist of a shell limestone TRIASSIC AND JURASSIC PERIODS. 161 (called in German Muschelkalk) between an underlying thick reddish sandstone (Bunter Sandstein) and overlying strata of reddish and mottled marlytes and sandstone (Keuper of the Germans). In England (see No. 6 on map, page 118), the formation consists of reddish sandstone and marlytes; it is mostly confined to a region running north-northwest just east of the Paleozoic areas, and to an extension of this region westward to Liverpool bay (or over the interval between the two main areas) and up the west coast. This formation, in Europe, contains in many places beds of salt, and is hence often called the Saliferous group. At Northwich in Cheshire, in England, there are two beds of rock-salt, 90 to 100 feet thick; and in Europe there are simi- lar beds at Vic and Dieuze in Prance, and at Wurtemberg in Germany. The Jurassic rocks of Britain and Europe are divided into three principal groups : 1. The Liassic (No. 7 a on map of England, page 118), con- sisting of grayish compact limestone strata, called Lias. 2. The Oolytic (No. 76 on map, page 118), consisting mostly of whitish and grayish limestones, part of them oolitic (page 25). One stratum, near the middle of the series, is a coral- reef limestone, much like the reef-rock of existing coral seas, though different in species of coral. Near the top of the series there are some local beds of fresh-water or terrestrial origin, in what is called the Purbeck group, and one on the island of Portland is named, significantly, the Portland dirt-bed. The Solenhofen lithographic limestone is a very fine-grained rock (thereby fit for lithography), of the age of the Middle Oolyte occurring in Pappenheim in Bavaria. 3. The Wealden (No. 8 on the map of England), a series of beds of estuary and fresh-water origin, mostly clay and sand, but partly of limestone. They occur in Southeastern England. They are named Wealden from the region where first studied, called the Weald, covering parts of Kent, Surrey, and Sussex. 162 MESOZOIC TIME. REPTILIAN AGE. 2. Life. 1. Plants. The vegetation of the Triassic and Jurassic periods included numerous kinds of Ferns, both large and small, Catamites t and Conifers, and so far resembled that of the Carboniferous age. But there were no forests or jungles of Lepidodendrids and Sigillarids. Instead of these Carboniferous types, a group of trees and shrubs sparingly represented in the later Carbon- iferous, that of the Cycads, was eminently characteristic of the Mesozoic world. This group has now but few living species, and among Fig - 254 * the genera, Cycas and Zamia are those whose names are best known. The plants have the as- pect of Palms ; and Fig. 255. CYCADS: Fig. 254, Cycas circinalis(x -j-^j) j 255, leaf of a living Zamia ( x there was, therefore, in the Mesozoic forests a mingling of palm-like foliage with that of Conifers (Spruce, Cypress, and the like). But the Cycads are not true Palms. They are TRIASSIC AND JURASSIC PERIODS. 163 Fig. 256. Gymnosperms, like the Conifers both in the structure of the wood and in the fruit. The resemblance to Palms is mainly in the cluster of great leaves at the sum- mit, and in the appearance of the exte- rior of the trunk. Fig. 254 represents, much reduced, a modern Cycas, and fig. 255 the leaf of a living Zamia, one twentieth the actual length. The fossil remains of Cycads are either their trunks or leaves. A fossil species from the Portland dirt-bed is represented in fig. 256. The trunks of some Cycads have a height of 15 or 20 feet. In one important respect these Cycads resemble the Ferns, that is, in the unfolding of the young Figs. 257-261. Stump of the Cycad, Mantellia (Cycadeoidea) megalophylla Fig. 257, Podozamites lanceolatus ; 258, Pterophyllum graminioides ; 259, Clathropteris reo- tiusculus ; 260, Pecopteris (Lepidopteris) Stuttgartensis ; 261 a, Cyclopteris linnseifolia. 164 MESOZOIC TIME. REPTILIAN AGE. leaf, the leaf being at first rolled up into a coil, and grad- ually unrolling as it expands. The Cycads thus combine peculiarities of three orders of plants, Ferns, Palms, and Conifers, and are examples, therefore, of what are called comprehensive types. Fossil plants are common in the coal-regions of Eichmond, Virginia, and in North Carolina, and occur also in other localities. Figs. 256, 257 are parts of the leaves of two species of Cycads, from North Carolina. Figs. 258 to 260 represent a few of the ferns : Fig. 258, a Clathropteris, from East Hampton, Mass. ; Fig. 259, a Pecopteris, from Eichmond, Va., and the Trias of Europe; Fig. 260, a Cydopteris, from Eichmond, Ya. Large cones of firs have also been found. Several of the American plants are identical in species with those of the European Triassic, and a few nearer to Jurassic forms. 2. Animals. a. American. The American beds of the Atlantic border region are re- markable for the absence of true marine life : all the species appear to be either those of brackish water, or of fresh water, or of the land. 1. Radiates and Mollusks. In the beds of the Atlantic border Eadiates are unknown ; and the remains of Mollusks are of doubtful character. The Jurassic beds of the Eocky Mountain region and its western borders contain many spe- cies, and the Triassic of California a few. 2. Articulates. The shells of Ostracoid Crustaceans are common in Pennsylvania, Virginia, and North Caro- lina, but have not yet been found in New England. Fig. 261. Fig. 261 represents one of the little shells of these bivalve species, called an Estheria. It was long sup- posed to be Molluscan. The Estherice are brackish- water species. A few remains of Insects have been found, and, what is more remarkable, the tracks of several species. These tracks were TRIASSIC AND JURASSIC PERIODS. 165 Pigs. 262 - 264. 263 264 It N, \ A f\ f\ made on the soft mud, probably by the larves of the Insects, for certain kinds pass their larval state in the water. Fig. 262 represents one of these larves found in shale at Turner's Falls in Massachusetts; it resembles, according to Dr. Le Conte, the larve of a modern Ephemera, or May-fly. Figs. 263, 264 are the tracks of Insects. Pro- fessor Hitchcock has named nearly 30 species of tracks of Insects and Crustaceans. 3. Vertebrates. There are evidences of the existence of Fishes, Reptiles, Mammals, and probably Birds. With the ap- pearance of the last two types the sub-kingdom of Vertebrates was finally represented in all its ARTICULATES. Fig. c l asses mediaeva ( x \\) ; 263, 264, Tracks of Insects. The Fishes found in the American rocks are all Ganoids, although Selachian remains are common in Europe. Fig. 265 represents one of the species, reduced one half ; the tail is half vertebrated. In other species of these rocks it is not at all vertebrated, being like that of modern Ganoids ; and in them this old paleozoic feature of the Ganoids is finally lost. Fig. 265. Pig. 265, GANOID, Catopterus gracilis (x J); a, Scale of same, natural size. The Eeptiles of the era are known to us partly from their fossil bones, and partly from their footprints. The footprints indicate a wonderful varietv as to form and size. Bones have 166 MESOZOIC TIME. REPTILIAN AGE. been found, especially in Pennsylvania, North Carolina, and Nova Scotia. Fig. 266 represents a tooth, half the natural size, of a Nova Scotia species (Bathygnathus borealis of Leidy); and Fig. 267, a tooth of another, from North Carolina, Belodon prisons. Several kinds occur at Phoenixville, Pa., where there is literally a bone-bed. Figs. 268 - 270 a, represent the tracks of three species of Eeptiles from the Connecticut Valley beds ; 268 - 270 are the Figs. 266-270. REPTILES. Fig. 266, Bathygnathus borealis (x J); 267, Belodon priscus ; 267 a, section of same ; 268, 268 a, fore and hind feet of Anisopus Deweyanus (x ) ; 269, 269 a, ibid, of A. gracilis (x ); 270, 270 a, ibid, of Otozoum Moodii (x iV). impressions made by the fore-foot in each, and 268 a, 269 a, 270 a, of the hind foot. Fig. 270 is reduced to one eighteenth the natural size, the actual length of the track being 20 inches. The animal is called Otozoum Moodii by Hitchcock ; it appears to have walked like a biped, bringing its fore-feet to the ground only occasionally, impressions of these feet being sel- dom found. The animal had a stride of 3 feet, and must have been of formidable dimensions. Twenty-one consecutive tracks of an Otozoum were exposed to view in the summer of 1874 in one of the Portland quarries. TRIASSIC AND JURASSIC PERIODS. 167 Some of the Eeptiles made three-toed tracks, closely like those of birds ; and this fact has suggested the doubt whether also the three-toed tracks in connection with which no tracks of fore-feet have been found may not be Keptilian. These Eeptiles with three-toed tracks have several bird-like char- acters ; they are called Dinosaurs, this name, from 8ewos, terrible, and cavpos, lizard, having been given to some gigan- tic species of the Jurassic and Cretaceous periods. The tracks, which have been regarded as those of birds (no tracks of the anterior feet being known), are very numerous. The largest of them is one and a half feet long (Fig. 271), far ex- ceeding that of an Ostrich, and even surpassing that which the giant Moa of New Zealand might have made (p. 242). Fig. Figs. 271, 272. 271 272 Fig. 271, Track of Brontozoum giganteum (x ); 272, Slab of sandstone with tracks of Birds? and Reptiles (x ^TJ). 272 represents, on a small scale, a slab from the Connecticut Eiver sandstone covered with tracks of reptiles and the sup- posed birds, as figured by Hitchcock. The two tracks lettered a are added, of larger proportional size than the others, to show more distinctly the form. 168 MESOZOIC TIME. KEPTILIAN AGE. Pig. 273. Jaw-bone of Dromatherium sylvestre. The only relics of Mammals yet discovered in the American rocks are two jaw-bones (Fig. 273). They are from North Carolina, and belong to a species of the division of Mammals called Marsupials (see page 50), the same to which the Opossum belongs, which now inhabits the same region. The facts prove that the land population of Mesozoic America included Insects, Reptiles, Marsupial Mammals, and probably Birds ; and that the forests that covered the hills were mainly composed of Conifers and Cycads. The existence of birds is probable because (1) the tracks are pre- cisely those of birds as well as of Dinosaurs ; (2) it is im- probable that Mammals, the highest of Vertebrates, should have preceded birds in geological history ; and (3) remains of a true bird have been found in the Jurassic rocks of Europe. b. Foreign. The European and British rocks of these periods, especially 275 Figs. 274-277. RADIATES : Fig. 274, Prionastrsea oblonga (a Coral) ; 275, Encrinus liliiformis (a Crinoid) ; 276, Cidaris Blumenbachii (an Echinus) ; 277, Spine of same. TRIASSIC AND JURASSIC PERIODS. 1G9 of the Jurassic, abound in marine fossils, and afford a good idea of the Mesozoic life of the ocean. The remains of ter- restrial life are also of great interest, Marsupial Mammals occurring in the Triassic beds, and birds in the Jurassic. 1. Radiates. Polyp-corals are common in some Jurassic strata : they are related to* the modern tribe of corals, and not to the ancient. Fig. 274 represents one of the oolytic spe- cies. Crinoids are of many kinds, yet their number, as com- pared with other fossils, is far less than in the preceding ages; and they are accompanied by various new forms of Star-fishes and Echini (page 57). Fig. 275 represents one of the Triassic Crinoids, the Lily-Encrinite, or Encrinus lilii- formis; Fig. 276, an Echinus, from the Qolyte, stripped of its spines ; and Fig. 277, one of the spines separate. 2. Mollusks. Brachiopods are few compared with their number in the Paleozoic. The last species of the Paleozoic genera, Spirifer and Leptcena, lived in the early part of the Figs. 278-281. 281 278 MOLLTJSKS : Fig. 278, Spirifer "Walcotti ; 279, Gryphsea incurva 5 280, Trigonia clavellata 281, Viviparus (Paludina) fluviorum. Jurassic period. Fig. 278 represents one of these last of the Spirifer group. Lamellibranchs and G-asteropods abound in spe- cies, and under various new, and many of them modern, genera. 170 MESOZOIC TIME. REPTILIAN AGE. Species of the genus Gryphcea were common in the Lias and later Mesozoic rocks : they are related to the Oyster, but have the beak incurved. Fig. 279 represents a Liassic species. Trigonia (Fig. 280) is a characteristic genus of the Mesozoic ; the name alludes to the triangular form of the shell : the species figured is from the Ob'lyte. Fig. 281 represents a fresh-water snail-shell, a very abundant fossil in the fresh- water limestone of the Wealden, closely resembling many modern species. But the most remarkable and characteristic of all Mesozoic Mollusks were the Ceplialopods. This order passed its maxi- mum as to number and size in the Mesozoic, and hundreds of species existed. The last of the Paleozoic types of Orthocerata Pigs. 282, 283. 282 MOLLTJSKS : Fig. 282, Ammonites Humphreysianus ; 283, A. Jason. and Goniatites lived in the Triassic period. In the same pe- riod species of Ammonites, one of the most characteristic of Mesozoic groups, became common ; and, in the earliest Juras- sic, the first of Belemnites, another peculiarly Mesozoic type, appeared. The Ammonites had external chambered shells like the Nau- TRIASSIC AND JURASSIC PERIODS. 171 tili (page 55) and G-oniatites. Two Ob'lytic species are repre- sented "in Figs. 282, 283. One of them (Fig. 283) has the side of the aperture very much prolonged ; but the outer mar- gin of the shell, whether prolonged or not, is seldom well preserved. The partitions (or septa) within the shells of Ammonites are bent back in Flg * 284t many folds (and much plaited within each fold) at their junction with the shell, so as to make deep plaited pockets. The front view of the outer plate, with the entrances to its side-pockets, are seen in Fig. 284. The fleshy mantle of the animal descended into these pockets, and thus the animal was aided in holding firmly to its shell. The siphuncle in the Ammonites is dorsal. The Paleozoic Goniatites were of the Ammonite family, but Ammonites tornatus . the pockets were much more simple, the flex- ures of the margins of the partitions being without plications. The fossil Belemnite is the internal bone of a kind of Ce- phalopod, analogous to the pen or internal bone (or osselet) of a Sepia, or Cuttle-fish (see Fig. 289). It is a thick, heavy fos- sil, of the forms in Figs. 285, 286, having a conical cavity at the upper end. The fossils are more or less broken at this extremity ; when entire, the margin of the aperture is elon- gated into a thin edge, and sometimes, on one side, into a thin plate of the form in Fig. 287. The animal had an ink-bag like the modern Sepia ; and ink from these ancient Cephalo- pods has been used in sketching their fossil remains. Fig. 288 represents one of the ink-bags of the Jurassic Cephalo- pods. Fig. 289 is another related Cephalopod, showing some- thing of the form of the animal, and also the ink-bag in place. 3. Articulates. The Articulates included various shrimps, or craw-fishes (Fig. 290, a Triassic species), Crabs, and Te- tradecapod (or 14-footed) Crustaceans (Fig. 291, representing a species something like the modern Sow-bug), but no Tri- lobites ; also Spiders (Fig. 292), and species of many of the 172 MESOZOIC TIME. REPTILIAN AGE. orders of Insects. Fig. 293 is a Libellula, or Dragon-fly, of the Jurassic period, from Solenhofen ; and Fig. 294, the wing- case of a beetle, from the Stonesfield Oolyte. Figs. 285-289. MOLLTJSKS : Fig. 285, Belemnites clavatus ; 286, B. paxillosus ; 286 a, Outline of section of same, near extremity ; 287, View, reduced, of the complete osselet of a Belemnite ; 288, Fossil Ink-bags of a Cephalopod ; 289, Acanthoteuthis antiquus. 4. Vertebrates. The Fishes were chiefly Ganoids or Sela- chians. In the Triassic beds of Europe, as in America, oc- curred the last species of the vertebrated-tailed Ganoids, and the first of those having the tail not vertebrated. Fig. 295 represents one of the latter kind from the Lias. Among the TRIASSIC AND JURASSIC PERIODS. 173 SJiarks (or Selachians) the Cestraciont tribe, one of the most ancient, characterized by a pavement of grinding teeth (page Figs. 290-294. ARTICULATES : Fig. 290, Pemphix Sueurii ; 291, Archseoniscus Brodiei ; 292, Palpipes priscus ; 293, Libellula ; 294, Wing-case of a Buprestis. 52), still continued, and was very numerously represented. There were also, in the Jurassic beds, Sharks having sharp- rig. 295. 295 a VERTEBRATE : Fig. 295, Restored figure of .Echmodus (Tetragonolepis) from the Lias ( x 4) ; 295 a, Scales of same. edged teeth like those of the tribe of Sharks that inhabits modern waters. Reptiles were the dominant race in the Eeptilian world. 174 MESOZOIC TIME. REPTILIAN AGE. Among them Amphibians, the division most common in the Carboniferous age, passed their climax in the Triassic, while true Keptiles expanded and reached their maximum of size and grade near the close of the Jurassic or in the earlier half of the Cretaceous period. Figs. 296-298. VERTEBRATES : Fig. 296, Skull of Mastodonsaurus giganteus (x (x ); 298, Footprints of Cheriotherium (x j 297, Tooth of same The latter included species for each of the elements, the water, the earth, and the air. Among the Triassic Amphibians, one frog-like Ldbyrintho- dont had a skull over 2 feet long, of the form shown in Fig. 296 ; its mouth was set round with teeth 3 inches long (Fig. 297), and the body was covered with scales. The specimen here figured was found in Saxony. It is probable that some of the American Reptilian species whose tracks are so com- mon in the Connecticut Valley were of this type. Fig. 298 is a reduced view of hand-like tracks, from the same locality as the above, supposed to have been made by an animal of the same species. The frogs of the present day are feeble and diminutive compared with the Triassic Amphibians. Among true Reptiles there were, first, Swimming Beptiles, called Enaliosaurs because of their living in the sea (from the Greek evd\ios t of the sea, and cravpos, lizard) ; they prob- TRIASSIC AND JUEASSIC PERIODS. 175 ably existed in the Carboniferous age (page 132), but became numerous and of great size in the Middle Mesozoic. They had paddles like Whales, and thus were well fitted for marine life. The most common kinds were the Ichthyosaurs and Ple- siosaurs. Figs. 299-303. VERTEBRATES: Fig. 299, Ichthyosaurus com munis (x TOTT) : 300, Head of same ( x 301 a, 301 b, View and section of vertebra of same ( x ) ; 302, Tooth of same, natural size ; 303, Plesiosaurus dolichodeirus ( x inj) ; 303 a, 303 6, View and section of vertebra of same. The Ichthyosaurs (Fig. 299) had a short neck, a long and large head, enormous eyes, and thin, doubly-concave, and therefore fish-like, vertebrae. The name is from the Greek Iffirt* fish, and ren and the Pacific border it is probable that some Cretac&jurs species continued on into the Tertiary, as stated beyond (page 209). There is no reason for asserting that the species of tjhe open ocean were exterminated ; on the contrary, it is believed that at least one Cretaceous Mollusk a Terebratula still exists in the depths of the Atlantic. Besides the destruction of species, there was the final ex- tinction of several families and tribes. The great family of Ammonites^ and many others of Mollusks, all the genera of Reptiles excepting Crocodilus, and others in all departments of life, came to their end at the close of the Cretaceous or soon after. Extermination over so wide a range of Continental seas must have been due to a cause which acted as widely, and no other appears to be sufficient excepting a change of climate CENOZOIC TIME. 201 in the north. The Arctic and other high-latitude regions may have been elevated more than those of lower latitudes, for Tertiary rocks do not occur on the eastern borders of the American continent north of the parallel of 42 N. to show that the continent was then below its present level. Con- nected with the elevation of the land to the north there may have been an exclusion of warm oceanic currents from the Arctic seas ; for in Behring Straits the depth of water is less than 200 feet. By these means a semi-glacial epoch may have been occasioned which sent cold oceanic currents from the north along the sea-borders and Continental seas to the south. Should the cold winds and cold oceanic currents of the north- ern part of the existing temperate zone penetrate for a single year into the tropical regions, they would produce a general extermination of the plants and animals of the land, and also of those of the coast and sea-borders, as far as the cold oceanic currents extended. A change to a climate no colder than the present would have been sufficient probably for all the de- struction that took place, since the life of the Cretaceous seas, even in Northern Europe, was largely that of the warm-tem- perate zone. While the emergence of northern lands here appealed to may have taken place as the Cretaceous period closed, there appears to have been no mountain-making of much extent until the Tertiary age had already far advanced (page 218). IV. CENOZOIC TIME. 1. Age of Mammals. Cenozoic time covers two ages : 1. THE TERTIARY AGE, or AGE OF MAMMALS ; and 2. THE QUATER- NARY, or AGE OF MAN. 2. General characteristics, In the transition to this era the life of the world takes on a new aspect. Trees of modern types Oak, Maple, Beech, etc., and Palms unite with 202 CENOZOIC TIME. Conifers to make the forests ; Mammals of great variety and size, Herbivores, Carnivores, and others, successors to the small semi-oviparous Mammals, tenant the land in place of Reptiles ; Birds and Bats possess the air in place of reptilian Birds and Pterodactyls; Whales and Teliost or common Fishes, with Sharks, mainly of modern type, occupy the waters in place of Enaliosaurs, and almost to the exclusion of the ancient tribes of Cestraciont Sharks and Ganoids. Finally Man appears when Mammals were passing their maximum in grade and magnitude, and becomes the domi- nant species of the finished world. I. TERTIARY AGE, or AGE OF MAMMALS. The Mammals of this age are all extinct species, and the other species of life mostly so ; the number of living species of Invertebrates (Eadiates, Mollusks, and Articulates) varies from perhaps one per cent in the early part of the period to 90 in the latter. In the Quaternary the Mammals of the earlier part are nearly all of extinct species ; the Invertebrates are almost wholly of living species, not over 5 per cent being extinct. I . Periods. The Tertiary strata have been divided by Lyell into three groups : 1. Eocene (from the Greek 770)9, dawn, and Kaivos, recent) : species nearly all extinct. 2. Miocene (from fjLicov t less, and icawos) : less than half the species living. 3. Pliocene (from TrXetW, more, and KCLIVO*;) : more than half the species living. These subdivisions are not necessarily those marked off by the grander physical changes of a continent. In North America there was : 1. The Lignitic period, corresponding to the Lower Eocene. TERTIARY AGE. 203 The beds follow on conformably after the Cretaceous ; and then, as the period closed, these Lignitic strata, along with the underlying Cretaceous, were together upturned, folded into mountains, and partly rendered metamorphic ; and this hap- pened both in the Rocky Mountain region and in California. This mountain-making epoch makes a natural ending of the period. 2. The Alabama period, corresponding to the Middle and Upper Eocene. The beds in the Eocky Mountain region overlie nearly or quite horizontally the upturned Lignitic and Cretaceous beds. On the Gulf of Mexico they include the marine beds of Claiborne, Alabama, and of Jackson and Vicksburg, Mississippi. The close of the period was marked off by a change over the lower part of the Mississippi Valley about the Gulf; for no marine Tertiary strata later than Eocene exist in those regions. The country in the line of Florida to the northwest, now 300 to 700 feet above the sea- level, is the western boundary of the area of the later Ter- tiary. 3. Yorktown, or that of the beds of Yorktown, Virginia, in which 20 to 40 per cent of the species are living, usually called Miocene, but possibly including part, at least, of the Pliocene. A fourth has been separated as Pliocene, or the Sumter epoch, based on observations on the beds in Sumter and Dar- lington districts, South Carolina ; but according to Conrad, it may not be distinct from the Yorktown. 2. Rocks: Kinds and Distribution. The beds are either of marine or of fresh-water origin. The marine Tertiary beds of North America border the continent south of New England along both the Atlantic Ocean and the Mexican Gulf, overlying the Cretaceous in part. The most northern locality is on Martha's Vineyard. (See map, page 69, in which the area is lined obliquely from the left above to the right below.) They spread northward 204 CENOZOIC TIME. to the mouth of the Ohio, and also westward into Texas, west of the Mexican Gulf. The marine Tertiary beds do not, like the Cretaceous, stretch north and northwest up the eastern slopes of the Eocky Mountains ; but, instead, there are over these slopes extensive fresh-water Tertiary strata (formed in and about great lakes), with in many places some of the lowest beds of brackish-water origin, as shown by the fossils. This fresh- water Tertiary extends over the summit region of the Eocky Mountains; and there the lower part includes not only brackish-water, but also salt-water, beds, along with those of fresh-water formation. Marine Tertiary occurs also in California and Oregon, not far from the coast. The Lignitic period, or early Eocene, includes the marine and brackish-water, and associated fresh-water, strata of the Upper Missouri and Eocky Mountain regions. They are re- markable for containing extensive beds of good mineral coal, called brown coal or lignite, whence the name of the period. These coal-beds are worked at Evanston, Coalville, and other places on or near the Central Pacific Eailroad. In Colorado and New Mexico the Lignitic Tertiary passes downward, according to the statements of some observers, into lignitic strata that belong to the Upper Cretaceous. Lignitic beds underlying the marine Tertiary of the Missis- sippi Valley south of the Ohio are also of this era. The Alabama period, or the Middle and Later Eocene, comprises the marine Tertiary of the Gulf border from Mis- sissippi eastward, and the lower beds of the Tertiary forma- tion along the Atlantic border. To the Yorktown period, or Miocene, belong the marine Ter- tiary beds of the Atlantic border from New Jersey to South Carolina, overlying the Eocene ; and fresh-water strata of great extent in the Upper Missouri region and elsewhere over the eastern slopes of the Eocky Mountains. The Pliocene Tertiary, besides including possibly marine beds in South Carolina, as mentioned above, comprises fresh- TERTIARY AGE. 205 water beds in the Upper Missouri region, and to the south, where they overlie the Miocene fresh-water strata, and, like them, are of lacustrine origin. The Tertiary rocks are generally but little consolidated; they consist mostly of compacted sand, pebbles, clay, earth that was once the mud of the sea-bottom or of estuaries, mixed often with shells, or are such kinds of deposits as now form along sea-shores and in shallow bays and estuaries, or in shallow waters off a coast. There are also limestones made of shells, and others of corals, resembling the reef- rock of coral seas. The latter are found mainly in the States bordering on the Mexican Gulf. Another variety of rock is buhrstone, a cellular siliceous rock, flinty in texture, used, on account of its being so hard and at the same time full of irregular cavities, for making millstones. It is found in South Carolina and Alabama. The Tertiary of Great Britain occurs mostly in the south- eastern part of England, in the London basin as it is called, and on the southern and eastern borders of the island, adjoin- ing the Cretaceous. On the continent of Europe the Paris basin is noted for its Eocene strata and fossil Mammals. Other Tertiary areas are those of the Pyrenean and Mediterranean regions, those of Switzerland, of Austria, etc. Some of the marine Fig. 335. Eocene beds contain Ehizopods (p. 59) having the shape of a coin, called Nummulite (from the Latin nummus, a coin). One is here figured, of natural size ; it has the exterior of half of it removed to show the cells within. Occasion- ally the beds are so far made up of these Nummulites that the rock is called Nummulitic limestone. These marine Eocene strata spread very widely over Eu- rope, Northern Africa, and Asia, occurring in the Pyre- nees, forming some of their summits ; in the Alps to a height of 10,000 feet ; in the Carpathians, in Algeria, in Egypt, where the most noted pyramids are made of Nummulitic limestone, 206 CENOZOIC TIME. in Persia, in the Western Himalayas (the region of Cash- mere), to a height of 16,500 feet. The later Tertiary forma- tions are much more limited in distribution, and many are of terrestrial or fresh-water origin. The rocks are similar to those of North America, but in- clude more of hard sandstone and limestone. The sandstone is a very common building-stone in different parts of Europe, being soft enough to be worked with facility, yet generally hardening on exposure, owing to the fact that it contains cal- careous particles (triturated shells), which render the perco- lating waters or rain calcareous, so that on evaporating they produce a calcareous deposit, as a cement, among the grains of sand. The Eocene formation of Southeastern England consists of beds of clay and sand, the lowest of sand sometimes contain- ing rolled flints. The Lower Eocene includes the Thanet sands, Woolwich beds, and London clay ; the Middle Eocene, the lower Bagshot beds ; the Upper Eocene, the Barton clay, Bembridge beds, and the Hempstead beds near Yarmouth. The Older Pliocene includes the Coralline crag and Eed crag of Suffolk ; and the Newer Pliocene, the Norwich crag, which is of fluvio-marine origin. No marine Miocene beds have yet been identified in Great Britain. I. Life. 1. Plants. The great feature of the Tertiary vegetation is the preva- lence of Angiosperms, the tribe of plants which made its first appearance in the Cretaceous. Leaves of Oak, Poplar, Maple, Hickory, Dogwood, Mulberry, Magnolia, Cinnamon, Fig, Syca- more, Willow, and many others, have already been found in both American and European Tertiary strata, besides the re- mains of Palms and Conifers. A leaf of a Tertiary Fan-palm (species of Sabal), found in the Upper Missouri, must have been, when entire, 12 feet in breadth. Nuts are also common in some beds, as at Brandon, Vermont. Fig. 336 is the TERTIARY AGE. 207 leaf of an Oak ; Fig. 337, of a species of Cinnamon ; Fig. 338, of a Palm ; Fig. 339, the nut of a beech, closely like that of Figs. 336-340. Fig. 336, Quercus myrtifolia?; 337, Cinnamomum Mississippiense ; 338, Calamopsis Danac; 339, Fagus ferruginea?; 340, Carpolithes irregularis. the common beech ; Fig. 340, another nut, from Brandon, of unknown relations. Figs 341-346 The Eocene Plants of Great Britain included Palms, and among those of Central and South- ern Europe there were many spe- cies related to the trees of Austra- lia; while the Miocene and Plio- cene had much similarity to those of America. The microscopic plants which form siliceous shells, called Diatoms (Figs. 341 to 346, all Diatoms. 208 CENOZOIC TIME. greatly enlarged), make extensive deposits in some places. One stratum near Kichmond, Virginia, is 30 feet thick, and is many miles in extent ; another, near Monterey, California, is 50 feet thick, and the material is as white and fine as chalk, which it resembles; another, near Bilin in Bohemia, is 14 feet thick. The material from the latter place was used as a polishing-powder (and called Tripoli, or polishing-slate) long before it was known that its fine grit was owing to the re- mains of microscopic life. Ehrenberg has calculated that a cubic inch of the fine earthy slate contains about forty-one thousand millions of organisms. Such accumulations of Dia- toms are made both in fresh waters and salt, and those of the ocean at all depths. 2. Animals. The most prominent fact with regard to the Tertiary In- vertebrates is their general resemblance to modern species. Although a number of the genera are extinct, and nearly every Eocene species, there is still a modern look in the re- Pigs. 347-351. 349 847 350 LAMELLIBRANCHS : Fig. 347, Ostrea sellseformis ; 348, Crassatella alta ; 349, Astarte Conradi ; 350, Cardita planicosta. GASTEROPOD : 351, Turritella carinata. mains, and the specimens have often the freshness of a shell from a modern beach. TERTIARY AGE. 209 The preceding are figures of a few Mollusks of the marine Eocene, from Claiborne Alabama. Fig. 347 represents an Eocene Oyster ; Fig. 348, a species of Crassatella ; Fig. 349, an Astarte; Fig. 350, a Cardita ; and Fig. 351, a Turritella. Figs. 352 to 355 are species of Miocene shells, from Virginia ; figs. 352, 353 represent a very common Crepidula, Figs. 352-355. 354 GASTEROPOD : Figs. 352, 353, Crepidula costata. L AMELLIBRANCHS : Fig. 354, Yoldia liinatula ; 355, Callista Sayana. upper and under sides. The species of the epoch include the common Oyster and Clam, and other modern species ; and these are, therefore, among the most ancient of living species on the globe. The Lignitic beds of the Kocky Mountain region in Wyoming Territory and elsewhere contain a very few Cretaceous species, among them the Inoceramus proble- maticus. With regard to Vertebrates the points of special interest are the following : 1. In the class of Fishes : (1) The prevalence of Teliosts, or fishes allied to the Perch and Salmon, as already stated ; and (2) the abundance of Sharks, some of them having teeth 6 inches long and broad. The teeth of sharks are the durable part of the skeleton ; they are very abundant in both Eocene and Miocene beds. Fig. 356 represents a tooth of the Car- charodon angustidens. The larger teeth above alluded to belong to the Carcliarodon megalodon, and are found at different places on the Atlantic border from Martha's Vineyard southward. 210 CENOZOIC TIME. Figs. 356, 357. Fig. 357 represents the tooth of another common kind of Shark, a species* of Lamna, from Claiborne. In the class of Eeptiles : The existence of numerous Croco- diles and Turtles. The shell of one of the Miocene turtles, found fossil in India, had a length of 12 feet, and the animal is supposed to have been 20 feet long. The first of true Snakes, moreover, occur in the Eocene. Dinosaurian remains, unknown in Europe above the Cretaceous, occur sparingly in the Lignitic beds of the Rocky Mountain region, and have strengthened the doubt whether these beds are not part of the Upper Cre- taceous. In the class of Birds : The species found are not long-tailed, or in any respect reptilian, but resemble mod- ern birds ; they are related to the Pelican, Waders, Pheasants, Perchers, TEETH OF SHARKS. -Fig. ase, Cultures Owls, Woodpeckers, and Carcharodon angustidens ; 357, Other Kinds. In the class of Mammals : The occurrence of the first of Whales, the first of Carnivores, Her- bivores, Rodents, Monkeys, and of other tribes, indicating a large population of brute animals, different from the present in species, though, in general, related to the modern kinds in form and structure. A few, however, are widely diverse from anything in existence, such combinations as the mind would never have imagined without aid from the skeletons furnished by the strata. In the early Eocene there appear to have been more Her- bivores than Carnivores ; but afterward the Carnivores were as common as now. Cuvier first made known to science the existence of fossil TERTIARY AGE. 211 Tertiary Mammals. The remains from the earthy beds about Paris had been long known, and were thought to be those of modern beasts. But, through careful study and comparisons with living animals, he was enabled to bring the scattered bones together into skeletons, ascertain the tribe to w T hich they belonged, and determine the food and mode of life of the ancient but now extinct species. Cuvier acquired his skill by observing the mutual dependence which subsists between all parts of a skeleton, and, in fact, all parts of an animal. A sharp claw is evidence that the animal has trenchant or cut- ting molar teeth, and is a flesh-eater ; a hoof, that he has broad molars and is a grazing species ; and, further, every bone has some modification showing the group of species to which it belongs, and may thus be an indication, in the hands of one well versed- in the subject, of the special type of the animal, and of its structure, even to its stomach within and its hide without. One of these Paris beasts from the middle Eocene beds is called a Paleothere, from the Greek TraXaio'?, ancient, and v, wild beast. It is related to the modern Tapirs (Fig. Fig. 358. Tapirus Indicus. 358), and was of the size of a horse. Another kind, called a Xiphodon, was of more slender habit, and somewhat resembled 212 CENOZOIC TIME. a stag, as shown in Fig. 359. There were others, related to the hog, or Mexican Peccary ; also some Carnivores, a Bat, and an Opossum. Among American Eocene Mammals there is a species of whale of great length, called a Zeuglodon, from %evy\7), yoke, and oSoi;?, tooth, in allusion to the fact that part of the teeth have two long prongs which give them a yoke-like shape. Fig. 359. Xiphodon gracile. The bones occur in many places in the Gulf States, and in Alabama the vertebrae were formerly so abundant as to have been built up into stone walls, or burned to rid the fields of them. The living animal was probably 70 feet in length. One of the larger vertebrae measures a foot and a half in length and a foot in diameter. The Lignitic beds, or early Eocene of North America, have afforded no Mammalian remains. But, from the overlying Middle or Later Eocene, of the Green Kiver basin, near Fort Bridger, a large number of species have been obtained. The skull of one kind, of elephantine size, having six horn-cores, and called by Marsh Dinoceras, in allusion to its horns, is rep- resented in Fig. 360. It was somewhat related to the Khino- ceros. There were also the earliest of the Horse tribe, called Orohippus; and it is remarkable that these Eocene Horses had four usable toes (Fig. 361) instead of the one only of the TERTIARY AGE. 213 modern Horse. The relations in the foot of the latter to dif- ferent kinds of Tertiary Horses are illustrated in Figs. 361-364. Fig. 360. Dinoceras miraMle ( x ). In Fig. 364 it is shown that the modern Horse has one usable toe, the third, and rudiments of two others, the second Figs. 361-364. 362 w FEET OF SPECIES OF THE HORSE TRIBE. -Fig. 361, Orohippus, of The Eocene (x |); 362, Anchitherium, of the Miocene; 363, Hipparion, of the Pliocene; 364, the modern Horse. 214 CENOZOIC TIME. and fourth, in what are called the splint-bones. In the Hip- parion, of the Pliocene (Fig. 363), the second and fourth have hoofs, but they are not usable. In Anchitherium, of the Mio- cene (Fig. 362), the second and fourth toes come to the ground, and are therefore usable. In Orohippus (Fig. 361) there are four toes, the second, third, fourth, and fifth, and all are usable. Other Wyoming species are related to the Tapir and Hog, some approaching in characters the Paris Paleothere. There were also Monkeys, some Carnivores related to the Cat and Wolf, Bats, Squirrels, Moles, and Marsupials. The Miocene beds of the " Bad Lands " on the White River, in the Upper Missouri region and elsewhere in the West, have afforded remains of other Mammals. Tig. 365. Among them are several Tooth of Titanotherium Proutii (X Carnivores related somewhat to the Hyena, Dog, and Panther ; many Herbivores, including Rhinoceroses, species approaching the Tapir, Peccary, Deer, Camel, Horse; Rodents. Fig. 365 Fig. 366. Teeth of Rhinoceros (Hyracodon) Nebrascensis. represents a tooth, half the natural size, of a Titanothere, an animal related to the Tapir and Paleothere, but of elephan- tine size, standing probably 7 or 8 feet high. Fig. 366 repre- TERTIARY AGE. 215 sents a few of the teeth of an animal related to the Rhinoceroses. Another species, the Brontotherium, nearly as large as an Elephant, but related somewhat to the Ehinoceros, had a pair of great horns. Pig. 367- Fig. 368. Oreodon gracilis. Fig. 367 represents the skull of another Miocene Mammal, called an Oreodon, which is intermediate between the Deer, Camel, and Hog. Remains of a Camel and Rhinoceros, and some of the tapir-like beasts, have been found in the Miocene of the Atlan- tic border. In the Pliocene beds of the Upper Missouri region still other species occur; including Camels, a Rhinoceros, an Elephant, a Masto- don, Horses, Deers, a Wolf, a Fox, a Tiger, a range of species quite Oriental in character. Among Mammals of the Euro- pean Miocene there were Elephants, Mastodons, Deer, and Dinotherium giganteum (X 216 CENOZOIC TIME. other Herbivores, many Carnivores, Monkeys, Ant-eaters, etc. One of the most singular species is the Dinothere, the form of the skull of which is shown in Fig. 367 ; its actual length is 3 feet 8 inches. It appears to have had a proboscis like an Elephant, but the tusks proceeded from the lower instead of upper jaw, and were bent downward. The earliest of the Bovine or Ox group occur in the Euro- pean Pliocene. 4. General Observations. 1. Geography. The Tertiary period completed mainly the work of rock-making along the borders of the continent, which Pigs. 369. Map of North America in the early part of the Tertiary Period. had been in progress during the Cretaceous period. The ac- companying map shows approximately the part of the conti- nent of North America under the sea toward the middle of TERTIARY AGE. 217 the Eocene Tertiary, or when the Lignitic period was near its close. By comparing it with the map of the Cretaceous con- tinent, page 194, it is seen that in the interval the Kocky Mountain region had become dry land. The occurrence of brackish-water beds in the Lignitic Tertiary of the Upper Missouri region, and of salt-water beds, as well as brackish- water, in the Lignitic of the summit of the mountains, indicate, as shown by Hayden, that the passage from the marine condi- tion of the Cretaceous era gradually changed into that of the fresh-water lakes and dry land of the later Eocene. The gradualness of the transition is further shown in the occur- rence of Lignitic or coal-bearing beds in the Upper Creta- ceous. After the Eocene, the elevation went forward, but still with extreme slowness, for in the Miocene the eastern slopes of the mountains were covered with immense fresh- water lakes, whose borders were the haunts of the Mammals of the era ; and these lakes were continued, though of dimin- ished size, into the Pliocene. The Cretaceous beds are now 10,000 feet above the sea-level, showing that this amount of elevation has taken place since that era ; but this height may not have been fully attained before the closing part of the Pliocene period. The area of the Mississippi river-system, embracing the slopes of the Eocky Mountains on the west and those of the Appalachians on the east, then for the first time attained its full dimensions. The Mexican Gulf was much larger in the Eocene period than at present ; but there was not that long extension northward which it had during the Cretaceous period. Florida was still submerged, and also all the bays of the Atlantic coast south of New York. After the Eocene epoch the Mexican Gulf became much more con- tracted by an elevation of the coast along the Gulf, accom- panying which the part of Georgia northwest of Florida, where Eocene and Cretaceous beds had been formed in the sea, was raised 300 to 700 feet above the sea-level. By the close of the Tertiary period the continent appears to have reached nearly its present outline. 10 218 CENOZOIC TIME. Besides the gradual changes, there was in the Bocky Moun- tain region and also in California the making of mountain ranges. At the close of the Lignitic period there were up- turnings of the Lignitic and Cretaceous formations, both to- gether, and high ridges in Colorado, Utah, and Wyoming are part of the results of the disturbances. Probably at the same time the Cretaceous strata of California, west of the Sierra Nevada, were made into mountains that are now part of the coast ranges. This was then one of the great mountain- making epochs in American Geological history. In the Orient the Eocene era was one of very extensive submergence of the land, as shown by the distribution of the nummulitic beds over Europe, Asia, and Northern Africa, as stated on page 205. Before the close of the Eocene, the greater part of these Continental seas became dry land, and in general continued so afterward ; for the marine Miocene and Pliocene are, comparatively, of limited extent. Many of the great mountains of the globe, as the Pyrenees, Alps, Carpa- thians, Himalayas, etc., received then a large part of their elevation, as is proved by their containing Eocene rocks in their structure, or by their bearing them about their summits. Thus it is learned that the elevation of the Pyrenees, though commenced before the close of the Cretaceous, was mainly produced in the middle or later part of the Eocene, as also that of the Julian Alps, the Apennines and Carpathians, and that of heights in Corsica. The Himalayas, in their western part about Cashmere, have nummulitic or Eocene beds, at a height of 16,500 feet ; so that even this great chain, although earlier elevated to the east, was not completed before the Middle Eocene ; and even later than this it received a consid- erable part of its elevation, as later Tertiary beds at lower levels show. The elevation of the Western Alps, including Mont Blanc, is referred by Elie de Beaumont to the close or latter part of the Miocene period; and that of the Eastern Alps, along the Bernese Oberland, to the close of the Plio- cene. An elevation of 3,000 feet took place in Sicily after the Pliocene. QUATERNARY AGE. 219 Many parts of the region of the Andes were raised 3,000 to 5,000 feet or more in the course of the Tertiary period. Climate. In Europe, the fact that, during the Eocene, Palms abounded in Britain, is evidence of a sub-tropical or warm-temperate climate even in its northern latitudes. The plants of the Miocene in Southern Europe are supposed to indicate a sub-tropical climate there during the middle Tertiary, but England had lost its palms and was cooler. In North America, the Eocene palms and other plants of the Upper Missouri region show that the temperature now found in the Dismal Swamp in North Carolina characterized in the Early Tertiary era the region of the Upper Missouri, the vicinity of the Great Lakes, and also Vermont, where ex- ists the Brandon deposit of nuts and lignite. The Camels, Ehinoceroces, and other animals of the Pliocene of the Upper Missouri, seem to prove that a warm-temperate climate still prevailed there in that closing epoch of the Ter- tiary period. It is therefore plain that the Earth had not as great a diver- sity of zones of climate as now ; and that Europe was little if any colder in the Eocene than in the Jurassic era. If the interval between the Cretaceous and Tertiary was one of un- usual cold, through Arctic and other elevations, as suggested on page 200, the cold epoch had mostly passed when the Eocene era opened. II. QUATERNARY AGE, or ERA OF MAN. 1. General characteristics. The Quaternary age was re- markable (1) for high-latitude movements and operations both north and south of the equator ; (2) for the culmination of the type of brute Mammals ; and (3) for the appearance of Man on the globe. 2. Periods. The periods are three : 1. The Glacial, or the period when, over the higher latitudes, the continents underwent great modifications in the features of the surface through the agency of ice. 220 CENOZOIC TIME. 2. The Champlain, when the ice disappeared, and the same high-latitude portions of the continent, and to a less extent the lower, were below their present level, and became covered by extensive fluvial and lacustrine formations, and along sea- coasts by marine formations. 3. The Recent or Terrace period, begun by a raising of the land nearly or quite to its present level. I. Glacial Period. The special effects of the operations that went forward in the Glacial period are the following : 1. Transportation. The transportation of a vast amount of earth and stones from the higher latitudes to the lower, over a large part of the breadth of a continent. The material consisted of earth, gravel, and stones, and also in some places broken trunks or branches of trees. Part of it was deposited in a pell-mell or unstratijied condition during the progress of the period, and part, either stratified or unstratified, in the opening part of the next period when the ice melted. This transported material is called Drift. Over the interior of the continent it contains no marine fossils or relics. At bottom there is often a bed of clay, called bowlder-clay, be- cause large stones or bowlders often occur in it. New England, Long Island, Canada, New York, and the States west to Iowa are in many parts thickly covered with this northern unstratified Drift. It reaches south to the lati- tude of 39, or nearly to the southern limits of Pennsylvania, Ohio, Indiana, Illinois, and Central Missouri, being rarely traceable south of the Ohio Eiver. Over the western half of the continent, west of the meridian of 98 W., the northern drift is mostly wanting. Besides this northern Drift, there are similar accumulations of earth and stones belonging to the same era, distributed lo- cally about some of the Appalachian ridges, south of Drift latitudes ; also on a grand scale about the higher ridges of the summit of the Eocky Mountains, and in the Sierra Nevada and other ranges and heights of the Pacific border region. QUATERNARY AGE. 221 The stones are of all dimensions, from that of a small peb- ble to masses as large as a moderate-sized house. One at Bradford in Massachusetts is 30 feet each way, and its weight is estimated to be at least 4,500,000 pounds. Many on Cape Cod are 20 feet in diameter. One lying on a naked ledge at Whitingham in Vermont measures 43 feet in length and 30 in height and width, or 40,000 cubic feet in bulk, and was probably transported across Deerfield Valley, the bottom of which is 500 feet below the spot where it lies. There are many great bowlders of trap from 50 to 1,000 tons in weight along the western border of the Triassico-Jurassic area in Connecticut; the line reaching to Long Island Sound, just west of New Haven ; and others similar, of equal magnitude, occur farther south on Long Island. The drift-material is coarsest to the north. The directions in which it travelled are in general between south westward and southeastward, and mostly between south- ward and southeastward. The material was carried south- ward across the Great Lakes and across Long Island Sound, the land to the south, in each case, being covered with stones from the land to the north. The distance to which the stones were transported in North America, as learned by comparing them with the rocks in place to the north, is mostly between 10 and 40 miles, though in some cases over 200 miles. 2. Scratches. The rocky ledges over which the drift was borne are often scratched, in closely crowded parallel lines, as in the following figure (Fig. 370). The scratchings or groov- ings are sometimes deep and broad channellings, and at times a yard or more deep and several feet wide, as if made by a tool of great size as well as power. At Kowe in Massachu- setts, on the top of Mount Monadnock, and in the sandstone of East Haven, west of New Haven, Ct., the scratches are of this remarkable character. The scratches occur wherever the drift occurs, provided the underlying rocks are sufficiently durable to have preserved them, arid they are usually of great 222 CENOZOIC TIME. uniformity in any given region. In some places two or more directions may be observed on the same surface. They are found in the valleys and on the slopes of mountains to a height, on the Green Mountains, of 4,400 feet, and on the "White Mountains of 5,500 feet. Fig. 370. Drift groovings or scratches. They often cross slopes and valleys obliquely, that -is-, without following the direction of the slope or valley. But, when so, it is usually found that these valleys are small tribu- taries to some greater valley. The scratches have a nearly common course over the higher levels ; but they generally conform to the directions of the great valleys of the land. Thus, in the Hudson Eiver Valley, between the Catskills and Green Mountains, the scratches have mostly the Hudson River course; so also in the Connecticut River Valley, the Merri- mack, and other valleys they have the course of the valley. The stones, or bowlders, are often scratched as well as the rocks. 3. European Drift. The Drift in Europe presents the same general course and peculiarities as in North America. It reaches south in some places to about latitude 50. The region south of the Baltic, and parts of Great Britain, are covered with drift and stones from Scandinavia. The distance QUATERNARY AGE. 223 of travel varies from 5 or 10 miles to 500 or 600. About the Alps and other high mountains south of Drift latitudes there are local accumulations of Drift of the Glacial area, and also scratches over the surface rocks. 4. Fiords. Fiords are deep, narrow sea-channels running many miles into the land. They occur on the coasts of Nor- way, Britain ; of Maine, Nova Scotia, Labrador, Greenland ; on the coast of Western North America north of the Straits of De Fuca; along that of Western South America south of latitude 41 S. Fiords are thus, like the Drift, confined to the higher lati- tudes of the globe, the Drift-latitudes ; and the two may have been of contemporaneous origin. 5. Origin of the Drift Nothing but moving ice could have transported the Drift with its immense bowlders. Glacier Theory. The ice is performing this very work now in the glacier regions of the Alps and other icy mountains, and stones of as great size have in former times been borne by a slow-moving glacier from the vicinity of Mont Blanc across the lowlands of Switzerland to the slopes of the Jura Mountains, and left there at a height of over 2,000 feet above the level of Lake Geneva. Moreover, there are in many places deposits of bowlder-clay, made of the earth formed by trituration of stones against stones during the moving of the glacier. Further, there are scratches, of precisely the same character as to numbers, depth, and parallelism, in the granitic and limestone rocks of the ridges ; and, besides, the transported material is left unstratified over the land, wherever it was not acted upon and distributed by Alpine torrents. Icebergs also transport earth and stones, as in the Arctic seas ; and great numbers are annually floated south to the Newfoundland banks, through the action of the northern or Labrador current, where they melt and drop their great bowlders and burden of gravel and earth to make deposits over the sea- bottom. But icebergs could not have covered great surfaces so regularly with scratches ; and, again, there are no marine 224 CENOZOIC TIME. relics in the unstratified drift to prove that the continent was under the sea in the Glacial period. There is a seeming difficulty in the Glacial theory, from the supposed want of a sufficient slope in the surface to produce movement. But a slope in the under surface is not needed, any more than for the flowing of pitch. Pitch, deposited in continued supply on any part of a plain, would spread in all directions around ; and this it would do if, instead of a plain, the surface beneath had an ascending slope. The slope of the upper surface of a plastic or fluid substance determines the rate of flow, not that of the under surface. Hence, if ice were accumulated over a region so that the upper surface had the requisite slope, there would be motion in the mass in the direction of this slope, whatever the bottom slope might be. At the same time the slope of the land at bottom, or the courses of the valleys, would determine to some extent the movement at bottom ; just as oblique grooves in a sloping board, down which pitch was moving, would determine more or less com- pletely the direction of the movement of the pitch that was in the grooves. All the facts or phenomena connected with the northern Drift are fully explained by reference to a great northern semi-continental glacier as the cause, and those relating to local drift in the Appalachians, Rocky Mountains, Sierra Ne- vada, Alps, and other high mountains south of Drift latitudes, on the view that local glaciers covered these heights in the Glacial period. The height to which scratches and drift occur about the White Mountains proves that the upper surface of the ice in that region was 6,000 or 6,500 feet ; and hence that the ice w r as not less than 5,000 feet thick over Northern New Eng- land. With a thickness of even 2,000 feet the glacier would have had great abrading power. Soft rocks would have been deeply ploughed up by it, and all jointed rocks, soft or hard, would have been torn to fragments, -and the loosened masses borne off. QUATERNARY AGE. 225 The stones and earth transported by the Continental glacier were gathered up by its lower part, from the surface of hills or ridges that projected into it, and even of the plains beneath it ; for there were no peaks rising above its upper surface to be a source of avalanches, as in the Alps. The cold of the Glacial period was probably due in part to the continents having at the time a higher level above the sea over the higher latitudes. This would not only produce greater cold through the extension and elevation of the lands, but also through its exclusion of the warm oceanic currents of the Atlantic and Pacific from their flow into the Arctic Zone. 2. Champlain Period. The Champlain period, as is proved by marine relics and by other facts described beyond, was an era of depression in the continents over the higher latitudes below the present level, and a depression which, within certain limits, increased to the northward. It was also a period, as indicated by the terres- trial life, of warmer climate than the Glacial ; and, probably, because of the lower level of the northern or high-latitude lands. The warmer climate appears to have determined the melting of the great glacier, and it caused this melting to go on widely over its surface ; so that, when it had thinned down the ice to within 500 or 1,000 feet, the disappearance of the rest of the ice went forward with accelerated progress. (1) The melting was thus the great event of the opening part of the Champlain period ; and it must have caused im- mense floods in all valleys, vastly beyond those from the breaking up of an ordinary winter. With the melting of the lower 1,000 feet, and during the era of floods, there would have been (2) the deposition of the earth, gravel, and stones contained therein; and in the de- position, wherever the material fell over the land, it would have gone down pell-mell and been left (a) unstratifted ; while, whatever fell into flowing streams, lakes, tidal estuaries, or along sea-coasts, would have been (6) stratified. The stratified 10* o 226 CENOZOIC TIME. deposits of the Champlain period are then either (1) of river- valley origin, (2) lacustrine, or (3) estuary or marine. After the era of floods or the Diluvial part of the Champlain period, the depositions in what may be called the Alluvial part of the period went on more quietly; and many land shells, bones, and other relics are contained in the river- valley deposits then made. The Diluvial beds consist of earth, clay, sand or pebbles, or of mixtures of these materials. And the Alluvial are partly the same, but more commonly of finer earth and clay. The river-border deposits occur in all or nearly all the river- valleys within the drift latitudes of the North American continent, from Maine to Oregon and California; and they exist farther south, extending along the Mississippi Valley to the Gulf of Mexico. The cold water descended the valley in a vast flood to the Gulf, bearing on its surface much drift ice from the dissolving glacier, the fact of the flood and that of the floating ice being proved, as Hilgard has shown, by the nature of the stratified deposits, and the occurrence of northern bowlders, 100 to 150 pounds in weight at least, as far south as the State of Mississippi. Facts prove also that the cold waters and ice in the Gulf were destructive to the tropical life along its northern borders. These river-valley deposits form at present elevated plains on one or both sides of the valley. Their elevation above the river is greater in Northern New England than in Southern ; and there is a like difference between those of the northern and southern parts of the States to the west of New Eng- land. The view in Fig. 371 represents a scene on the Connecti- cut, a few miles below Hanover in New Hampshire, where there are three different levels, or terraces, in the alluvial formation ; the upper shows the total thickness of the for- mation down to the river-level. Fig. 372 represents a section of a valley, with the allu- vial formation, //', filling it, and the channel of the river at E. QUATERNARY AGE. 227 Were the country to be elevated, the river would dig out a deeper channel as the elevation went on, and thus the top Tig. 371. Terraces on the Connecticut River, south of Hanover, N. H. of the valley formation would finally be left far above the river, beyond the reach of its waters. The river would, at the same Fig. 372. Section of a valley in the Champlain epoch, with dotted lines showing the terraces of the Terrace epoch. time, wear away a portion of this formation, either side, during its floods, and thus make room for a lower flat on its banks, over which the flooded waters would spread, as illustrated by the lines d d f , b b', in the figure ; for every river, not con- fined by rocks, has both its low-water channel and its flood- ground. 228 CENOZOIC TIME. The lacustrine deposits are of similar character to those of the valleys, and of like distribution over the continent ; and they are equally elevated above the present level of the water they border. The sea-border deposils, or those formed on sea-shores and estuaries, are found at many places on the coasts of New Eng- land, both the southern and eastern. At several localities in Maine they afford shells at heights not far from 200 feet above the sea-level. They form deposits of great thickness along the St. Lawrence, as near Quebec, Montreal, and King- ston ; at Montreal they contain numerous marine shells at a height of 400 to 500 feet above the river. They border Lake Champlain, being there 393 feet in height above its level; and, besides marine shells, the remains of a whale have been taken from the beds. In the Arctic regions similar deposits full of shells are common, at different elevations up to 600 or 800 feet, and in some places 1,000 feet, above the sea-level. These sea-border deposits, now elevated, must have been at the water-level, or below it, when they were formed ; that is, in the Champlain period. The facts prove that the river St. Lawrence was at that time an arm of the sea, of great breadth, with the bordering land 400 to 500 feet below its present level; that Lake Champlain was a deep lay opening into the St. Law- rence channel, and that it had its whales and seals as well as sea-shells ; that the coast of Maine was in part 200 feet or more below its present level, and Southern New England 40 feet or more. The present elevated positions of the river-valley and lacus- trine formations over the wide extent of the continent, from the Atlantic to the Pacific, are equally good evidence that its interior, in the Champlain period, was below its present level. There is thus reason for believing that the whole northern portion of the continent was less elevated than now ; and also that the depression was greatest to the north, since the sea- QUATERNARY AGE. 229 border, river- valley, and lacustrine formations are all at higher elevations to the north, or near the northern boundary of the United States, than they are to the south. The facts here stated with regard to elevated river-valley, lacustrine, and sea-border formations in North America have their parallel in Europe. In Great Britain the Glacial period was followed by one of depression, in which its northern por- tions were over 1,000 feet below their present level. The re- markable terraces or benches of Glen Eoy, in Scotland, are three in number, and 1,139, 1,039, and 847 feet above the sea- level. In Sweden there are sea-border beds with shells very similar to those of Maine and the St. Lawrence. The valley of the Ehine, and those of many other rivers of Europe, have their high terraces. While, therefore, the facts connected with the Glacial period favor the view that the northern portions of the continents were then much raised above their present level, those of the next or Champlain period prove that they were afterward much below their present level. It hence appears that there was an upward high-latitude movement for the Glacial period and a downward for the Champlain period ; and that the latter movement brought to its close the era of ice, by occasioning a warm climate. 3. Recent Period. When the Champlain period was in progress, the upper plain of the sea-border formations, now so elevated, was at the sea-level ; and the high alluvial plains along the rivers were the flood-grounds of the rivers. The land has since been raised ; and, during the progress of the elevation, the alluvial forma- tions were cut into terraces, as represented in Fig. 371, page 226, and the sea-border formations, also, were cut into other terraces, or " benches," of different levels. This elevation led to the making of terraces in the river- valley, lacustrine, and sea-border Champlain formations. In Fig. 372 there are dotted lines showing the levels of the 230 CENOZOIC TIME. river and its flood-plain at different periods in the progress of this elevation ; and Fig. 373 represents the terraces com- pleted. The successive terraces are not necessarily evidence of as many successive movements in the elevation of the continent, yet may be so in some cases. Fig. 373. Section of a valley with its terraces completed. As already stated, the river- valley formations throughout the continent are raised high above the present flood-plains of the rivers or lakes, and to a greater height in the northern portions of the country than in the southern. Hence, while the Champlain period was one of a low level in the continent, especially at the north, the Recent period began in a rising again, until the continent reached its present height ; and this rising was greatest at the north. The facts seem hence to sustain the conclusion that the high-latitude oscillations of this part of geological history were an upward movement for the Glacial period, a downward for the Champlain period, an upward again for the Recent period. There is no evidence that the movement resulted anywhere in the raising of a mountain-range ; there was simply a gentle bending upward, then a sinking, and then a rising again of the general sur- face. In Europe there was a second Glacial era, in which the northern portions of that continent were again covered with ice, and glaciers spread anew from the Alps over part of Lower Switzerland. It appears to have occurred at the close of the Champlain period, and to have been connected with the ris- ing of the land that introduced the Recent period, the rising having carried the land above its present level. Proofs QUATERNARY AGE. 231 of the occurrence of such an epoch are found in the remains of the Reindeer and other sub-arctic animals, in Southern France (page 238), in deposits that are subsequent in date to true Champlain deposits. The Eecent period is, hence, opened by this second Glacial epoch, while it closes with the modern or historical era. Modern Changes of Level. The sea, the rivers, the winds, and all mechanical and chemical forces are still working as they have always worked ; and, too, the earth is undergoing changes of level over wide areas, although it has beyond question reached an era of com- parative repose. These changes of level are either paroxysmal, that is, take place through a sudden movement of the earth's crust as sometimes happens in connection with an earthquake ; or they are secular, that is, result from a gradual movement prolonged through many years or centuries. The following are some examples : 1. Paroxysmal In 1822 the coast of Western South America, for 1,200 miles along by Concepcion and Valparaiso, was shaken by an earthquake, and it has been estimated that the coast near Valparaiso was raised at the time 3 or 4 feet. In 1835, during another earthquake in the same region, there was an elevation, it is stated, of 4 or 5 feet at Talcahuano, which was reduced after a while to 2 or 3 feet. In 1819 there was an earthquake about the Delta of the Indus, and simultaneously an area of 2,000 square miles, in which the fort and village of Sindree were situated, sunk so as to be- come an inland sea, with the tops of the houses just out of water ; and another region parallel with the sunken area, 50 miles long and in some parts 10 broad, was raised 10 feet above the delta. These few examples all happened within an interval of sixteen years. They show that the earth is still far from absolute quiet, even in this its finished state. 232 CENOZOIC TIME. 2. Secular. Along the coasts of Sweden and Finland, on the Baltic, there is evidence that a gradual rising of the land is in slow progress. Marks placed along the rocks by the Swedish government, many years since, show that the change is slight at Stockholm, but increases northward, and is felt even at the North Cape, 1,000 miles from Stockholm. At Udde valla the rate of elevation is equivalent to 3 or 4 feet in a century. In Greenland, for 600 miles from Disco Bay, near 69 N., to the frith of Igaliko 60 43' 1ST., a slow sinking has been going on for at least four centuries. Islands along the coast, and old buildings, have been submerged. The Moravian set- tlers have had to put down new poles for their boats, and the old ones stand "as silent witnesses of the change." It is suspected that a sinking is also in progress along the coast of New Jersey, Long Island, and Martha's Vine- yard, and a rising in different parts of the coast-region be- tween Labrador and the Bay of Fundy. There are deeply buried stumps of forest -trees along the sea-shore plains of New Jersey, whose condition can hardly be otherwise ex- plained. The above cases illustrate movements by the century, or those slow oscillations which have taken place through the geological ages, raising and sinking the continents, or at least changing the water-line along the land. This fact is to be noted, that these secular movements of modern time over the continents are, for the most part, so far as observed, high-latitude oscillations, just as they were in the earlier part of the Quaternary. Life of the Quaternary. The invertebrate animals of the Quaternary, and probably also the plants, were very nearly if not quite all identical with existing species. The shells and other invertebrate remains found in the beds on the St. Lawrence, Lake Cham- QUATERNARY AGE. ANIMAL LIFE. 233 plain, and on the coast of Maine, are similar to those now found on the coast of Maine or Labrador, or farther north. The life of the Quaternary of greatest interest is the Mam- malian, which type, as regards brutes, culminated in the Champlain period. This culmination was manifested in (1) the number of species, (2) the multitude of individuals, (3) the magnitude of the animals, the period in each of these particulars exceeding the present time. Along with the brute Mammals of the Quaternary ap- peared also Man. I. Brute Mammals. 1. Europe and Asia. The bones of Mammals are found in caves that were their old haunts ; in Drift and stratified Champlain deposits along rivers and lakes; in sea-border deposits ; in marshes, where the animals were mired ; in ice, preserved from decay by the intense cold. The caves in Europe were the resort especially of the Great Cave-Bear (Ursus spelceus), and those of Britain of the Cave-Hyena (Hycena spelcea). Into their dens they dragged the carcasses or bones of other animals for food, so that relics of a large number of species are now mingled together in the earth, or stalagmite, which forms the floor of the cavern. In a cave at Kirkdale, England, portions of a very large num- ber of Hyenas have been made out, besides remains of an Elephant, Lion, Tiger, Bear, Wolf, Fox, Hare, Weasel, Elii- noceros, Horse, Hippopotamus, Ox, Deer, and other species, all then inhabitants of that country. A cave at Gaylenreuth is said to have afforded fragments of at least 800 individuals of the Cave-Bear. The Cave-Hyena is regarded as a large variety of the Hymna crocuta of South Africa, and the Cave Lion, a variety of Felis leo, the Lion of Africa. But many of the species are now extinct. The fact that the numbers of species and of individuals in the Quaternary was greater than now, may be inferred from comparing the fauna of Quaternary Great Britain with that 234 CENOZOIC TIME. of any region of equal area in the present age. The species included gigantic Elephants, two species of Rhinoceros, a Hip- popotamus, three species of Oxen, two of them of colossal size, the Irish Deer (Megaceros Hibernicus), whose height to the summit of its antlers was 10 to 11 feet, and the span of whose antlers was in some cases 12 feet, Deer, Horses, Wild Boars, a Wild-cat, Lynx, Leopard, a Tiger larger than that of Bengal, a large Lion called a Machcerodus, having sabre-like canines sometimes eight inches long, the Cave-Hyena, Cave- Bear, besides various smaller species. Fig. 374. Skeleton of Mastodon giganteus. The Elephant (Elephas primigenius) was nearly a third taller than the largest modern species. It roamed over Britain, Middle and Northern Europe, and Northern Asia, even to its Arctic shores. Great quantities of tusks have been exported from the borders of the Arctic sea for ivory. QUATERNARY AGE. ANIMAL LIFE. 235 These tusks sometimes have a length of 12 J feet. Near the beginning of the century one of these Elephants was found frozen in ice at the mouths of the Lena ; and it was so well preserved that Siberian dogs ate of the ancient flesh. Its length to the extremity of the tail was 16 J feet, and its height 9J feet. It had a coat of long hair. But no amount of hair would enable an Elephant now to live in those bar- ren, icy regions, where the mean temperature in winter is 40 F. below zero. Siberia had also a hairy Bhinoceros. Although there were many Herbivores among the Qua- ternary species of the Orient, the most characteristic animals were the great Carnivores. The period was the time of tri- umph of brute force and ferocity, and the Orient was espe- cially the scene of its triumph. 2. North America. In the Champlain period there were great Elephants and Mastodons, Oxen, Horses, Stags, Heavers, and some Edentates, "in Quaternary North America, unsur- passed in magnitude by any in other parts of the world. Herbivores were the characteristic type. Of Carnivores there Fig. 375. Megatherium Cuvieri ( x ^- 5 -)- were comparatively few species ; no true cavern species have been discovered. Fig. 374 (from Owen) represents the speci- men of the American Mastodon now in the British Museum. 236 CENOZOIC TIME. The skeleton set up by Dr. Warren in Boston has a height of 11 feet and a length to the base of the tail of 17 feet. It was found in a marsh near Newburgh, New York. The American Elephant was fully as large as the Siberian. 3. South America. South America had, at the same time, its Carnivores, its Mastodons, and other Herbivores; but it was most remarkable for its Edentates, or animals related to the Sloths. Fig. 375 shows the form and skeleton of one of these animals, the Megathere. It exceeded in size the largest Rhinoceros : a skeleton in the British Museum is 18 feet long. It was a clumsy, sloth-like beast, but exceeded im- mensely the modern Sloth in its size. Another kind of Edentate had a shell like a turtle, and was somewhat re- lated to the Armadillo. One of them is called a Glyptodon (Fig. 376). The animals of this kind w r ere also gigantic, the Glyptodon here figured having had a length, to the extrem- ity of the tail, of nine feet. South America was eminently the continent of Edentates. Pig. 376. Glyptodon clavipes (X ^,). 4. Australia. Quaternary Australia, in the Champlain period, contained Marsupial animals almost exclusively, like modern Australia ; but these partook of the gigantic size so characteristic of the Mammalian life of the period. One species, called Diprotodon, was as large as a Hippopotamus, and another, the Nototherium, was as large as an ox. QUATERNARY AGE. MAN. 237 5. Conclusions. The facts sustain the following conclu- sions : 1. The Champlain period of the Quaternary was the cul- minant time of Mammals, both as to numbers and magni- tude. 2. Each continent was gigantic in that type of Mammalian life which is now eminently characteristic of it : The Orient, in Carnivores, and, it may be added, also in Monkeys ; North America, in Herbivores ; South America, in Edentates ; Aus- tralia, in Marsupials. 3. The climate of Great Britain and Europe, where were the haunts of Lions, Tigers, Hippopotamuses, etc., must have been warmer than now, and probably not colder than warm- temperate. The climate of Arctic Siberia was such that shrubs could have grown there to feed the herds of Elephants, and hence could not have been below sub-frigid, for which degree of cold it is possible the animals might have been adapted by their hairy covering. 4. The Champlain period, the meridian time of the Quater- nary Mammals, was hence, as before stated, one of warmer climate over the continents than the present, and much warmer than that of the Glacial period. The species may have begun to exist before the Glacial period ended in Eu- rope ; but they belonged pre-eminently to the Champlain period, when the sinking of the land over the higher latitudes had introduced the warmer climate. 5. The larger part of the great Mammals of the Quater- nary disappeared with the close of the Champlain period or in the early part of the Recent period, while others found refuge in the tropics. They were animals of a warmer cli- mate than now belongs to the regions which they then inhab- ited ; and the cold of the second Glacial era, with which the Recent period opened, probably brought about the extermina- tion and forced migration. Such an epoch of cold could not have been passed through by Europe without some refrigeration of the climate of North 238 CENOZOIC TIME. America, since the two continents are bound together by a common Arctic. The remains of Eeindeers have been found in Southern New York ; and they may have been driven so far south by the climate of that epoch, as the same animals were driven, in Europe, to Southern France. Among the Mammals of Europe which existed before the close of the Champlain period, some are now living ; as the Reindeer, Marmot, Ibex, Chamois, Elk, Wild Boar, Goat, Stag, Aurochs, Urus, Wolf, Brown Bear, and others. 2. Man. 1. Relics of Man. The earliest relics of Man in Europe are rude flint implements, as arrow-heads, chisels, etc. ; flint- chippings, or the chips thrown off in making the implements ; rude carvings ; human bones and skeletons ; the bones of the animals used for food, split lengthwise, this being done to get at the marrow ; charcoal, and other remains of fires. They occur associated with the remains of the Cave-Bear, Cave- Hyena, Cave-Lion, Elephant, and other species. They date from the Champlain period, and perhaps, in part, from the earlier Glacial period. 2. The Paleolithic Era. As the only implements of early Man in Europe were of stone, the era in human history has been called the " Stone age " ; and this earliest part of that age, above referred to, has t>een designated the Paleolithic era, from the Greek iroXoux?, ancient, and X/#o that of the Archsean (page 78) ; and all ranges of mountains later made in any part were approximately parallel to the earlier Archaean lines of that part (page 249). Thus the adult character- istics of the continent were as plainly manifested in its begin- nings as those of a Vertebrate in its embryo stage. 1. Why were mountains made along the borders of the Conti- nents, and why raised highest and in the largest number of long lines, and why attended by the mos't and loftiest volcanoes, on the sides of the largest ocean? The oceanic area, besides being depressed much below the continental, has, as observed above, 332 DYNAMICAL GEOLOGY. rather abrupt sides. Hence, while the lateral pressure in the crust was universal over the sphere, the force in the oceanic crust acted obliquely upward against the crust of the conti- nental border. The action was that of a shove or thrust from the direction of the ocean, and in each oceanic area was somewhat proportional to the extent of it ; conse- quently, bendings, uplifts, fractures, foldings of strata, earth- quakes, mountain-making, became eminently features of the continental borders, and most prominently so of the borders which faced the largest oceans. 2. Method of action, and its progress in North America. The two systems of forces engaged in the progress of North Amer- ica were those of the Atlantic and Pacific, the latter the greatest. Under their action the V-shaped Archaean dry land (map, page 73) was first defined, one branch stretching north- eastward to Labrador and the other northwestward to the Arctic, and thus facing respectively the Atlantic and Pacific ; while mountains were made along the course of the Appala- chian chain and the Blue and Highland ridges. It follows, from the courses of the arms of the V> and of the moun- tains, that the Atlantic force acted mainly from the south- eastward and the Pacific from the southwestward, and the two, therefore, nearly at right angles to one another. It is also apparent that the Pacific force even then was the greater, and hence the Pacific Ocean the larger; for the northwestward branch of the V is f ar the longer. Thus the Archaean nucleus was outlined, and the position of Hudson's Bay determined within the arms of the V- From this nucleal dry land progress went forward southeastward, or toward the Atlantic, and southwestward, or toward the Pacific, successive formations being added under gentle oscil- lations, and the dry land gradually extending under changes of level caused mainly by the same forces. Then, when the Lower Silurian closed, appeared the Green Mountains ; and when Paleozoic time was closing, appeared the Alleghany part of the Appalachian chain, parallel to the eastern branch RESULTS OF THE EARTH'S CONTRACTION. 333 of the Archaean heights. Later still rose the trap ridges of the Mesozoic on the Atlantic border (page 160), making an- other parallel to the eastern branch, or tripling the arm of the V on the east, and even repeating all the bends in the Appalachians. Again, on the Pacific side, other ranges were made parallel to the course of the Bocky Mountain chain; among them after the Jurassic period, the Sierra Nevada, Wahsatch, and Cascade range, the last with its many volcanoes, also Creta- ceous ranges, and still later Tertiary ridges, each epoch adding new parallels to the western branch of the Archaean nucleus. Finally, in the course of the Tertiary, the mass of the Rocky Mountains rose to its full height above the ocean. Each added range, as is seen, proves that the mountain- making forces continued to act to a large degree from the same directions as in Archaean time. The intersection of the uplifts produced by the Atlantic and Pacific forces may be distinguished over the interior of North America ; for the courses of the uplifts of the Coal-formation in Illinois and the trend of Florida are parallel to the Pacific border, and the line between these two intersects the Appa- lachian chain in Eastern Tennessee. Thus the continent made progress, adding layer after layer to the rocks over its surface, and range after range in parallel lines to its heights, until finally the continental area reached its limit, and the great interior basin had its mountain-bor- ders completed : on the east, the low Appalachians, and the trap ridges of the Mesozoic ; on the west, the massive and lofty Eocky Mountain chain, with the parallel ranges over its western slopes. It has been explained on page 243 that, when the continent was thus far completed, there occurred a change in the region moved by the forces. The high-latitude oscillations of the Quaternary then began. But the Pacific and Atlantic forces may have occasioned these new movements. For if, in the course of the changes through the geological ages, the por- 334 DYNAMICAL GEOLOGY. tions of the continental crust in lower latitudes, thickened by the successive formations, and stiffened by mountain-chains and metamorphism, had become less yielding than those of higher latitudes, the pressure from contraction would have produced its oscillations in the latter rather than in the former. Thus, the evolution of the features of the surface, even to the terraces made along the river- valleys in the last of the ages, may have taken place through one system of forces originating in one single cause, the earth's contraction from cooling. North America, which is here appealed to for ex- planations, affords the truest and clearest illustration of the principles involved, because it lies alone between the two oceans, the Atlantic and Pacific, with the nearest continent, South America, to the west of its meridians. The evolution, under the forces from the two directions, went forward on this account with great regularity, each age repeating the preceding in the direction of all oscillations, or uplifts. It was a single isolated individual making systematic progress throughout until its final completion, and exhibits truly the system in the earth's development. Europe, in contrast, has Africa on the south and Asia on the east ; it is, therefore, full of complexities in its feature lines and in the succession of events that make up its geological history. 4. Formation of Mountain Chains. 1. A Geosynclinal, or downward bend of the Crust, the first step in ordinary Mountain-making. In the making of the Appalachians there was first, under the lateral pressure, a slowly progressing subsidence; it began in, or before, the Primordial period, the commencing era of the Silurian, and continued in progress until the Carboniferous age closed. As the trough deepened, deposits of sediment, and sometimes of limestone, were made, that kept the surface of the region near the water level ; and, when the trough reached its maximum, there were 40,000 feet in thickness of stratified rock in it RESULTS OF THE EARTH'S CONTRACTION. 335 (page 151), and this, therefore, was the depth of the trough. The Green Mountains began in a similar subsidence, and at the same time; and the trough was kept full with deposits as it progressed; but it reached its maximum, or the era of catastrophe, at the close of the Lower Silurian. Such facts are in the history of many, if not all, mountains. 2. The bottom of the Geosynclinal weakened by the Heat rising into it from below. As planes of equal temperature within the earth have a nearly uniform distance from the surface, the accumulation of sedimentary beds in sinking trough would occasion, as Herschel long since urged, the corresponding rising of heat from below, so that, with 40,000 feet of such accumu- lations, a given isothermal plane would have been raised 40,000 feet. Under such an accession of heat, the bottom of the trough would have been greatly weakened, if not partly melted off. If the lower surface of the crust had dipped down this much into the plastic layer that was beneath it, it would have been actually melted off. 3. The Heat in the lower part of the trough increased by the transformation of motion into heat The heat from the trans- formation of the motion of the crust would have been of feeble amount, if the motion was extremely slow and regular. But, with fractures, shovings, and crushing accompanying it, the heat from the rise of the isogeothermal would have been much reinforced. 4. The weakened trough yields before the pressure. The lateral pressure, acting against a trough thus weakened, would end, as Hunt has observed, in causing a collapse, that is, a catastrophic break of the trough below, and a pressing to- gether of the stratified beds within it. And with this break the shaping of the mountain would begin. 5. Character of the Mountain thus made. Under such cir- cumstances the stratified rocks would be folded, profoundly broken, shoved along fractures, and pressed into a narrower space than they occupied before ; and thus they would become raised, as argued by Le Conte, above their former level, so that 336 DYNAMICAL GEOLOGY. a mountain range would be the result, even without any actual uplift of the crust beneath. The crust beneath was that of the geosyiiclinal ; and lateral pressure, however powerful, could not possibly have raised at the time the downward flexed crust. 6. The finished Mountain Range a Synclinorium. Such a mountain range, begun in a geosynclinal and ending in a catastrophe of displacement and upturning, is, as named by the author, a synclinorium, it owing its origin to the progress of a geosynclinal. (The word is from the Greek for synclinal, and o/oo?, mountain) Although at first consisting of a series of parallel folds of strata, with the anticlinals greatly broken, the anticlinals, perhaps two, or three, or more miles in height, denudation, after pursuing its work for a while, would reduce it to a group of synclinal ridges. The fractured anticlinals are easily worn away ; while the synclinals have the elements of greater permanence, in being much less broken above, and in having their rocks folded and pressed together, if a close synclinal, and thus made firmer and more durable, even if not also crystallized by metamorphism. The syncli- nals of greatest breadth and depth, other things being equal, should become ultimately the highest of the mountain ridges, because more material is embraced in them. In the Taconic Mountains, on the western border of Massachusetts, Mount Washington (including Mount Everett) and Graylock are the high peaks, for the reason just explained. Other portions of the Taconic range are made of narrower portions of the syn- clinal, and are less elevated. 7. A Mountain Chain may comprise Synclinoria of different ages. The Appalachian chain consists of (1) mountains of Archaean rocks, that were made in pre-Silurian time ; (2) the Green Mountains, that date from the close of the Lower Silurian; and (3) the Alleghanies, that were formed at the close of the Carboniferous age. The Green Mountains began in the same great geosynclinal with the Alleghanies ; but that northern part of it reached its completion and catastrophe RESULTS OF THE EARTH'S CONTRACTION. 337 long before the Alleghany part, probably because so near the Adirondack border of the stable part of the continent. It is probable that the Archaean portion of the Appalachian chain, which includes the Blue Ridge, the New Jersey Highlands, continued in Dutchess County, N. Y., and the Adirondacks, corresponds to another older synclinorium. Thus a mountain chain may comprise several synclinoria made at widely differ- ent epochs. The several areas of the Triassico-Jurassic sandstone (page 159) were areas of subsidence or sinking troughs, and of sedi- mentary accumulations in progress in each trough ; and the geosynclinal, in each case, ended in catastrophe, as exhibited in upturned or displaced rocks, and in many lines of great fractures, giving exit to igneous rocks. The progress was like that in the case of a synclinorium, although no true mountain- chain was made. 8. Metamorphism and other attendant effects. The heat developed through the transformation of motion, added to that rising into the strata from below, would produce all the consolidation and crystallization which has been, in any case, observed ; and would cause, as lighter effects, the change of brown oxyd of iron to red oxyd, thereby reddening sandstones and clays, or make other decompositions in which red oxyd of iron is developed ; and also debituminize mineral coal, and evolve mineral oil from black hydrocarbon shales (like the Black shale of the Hamilton), to be condensed in cavities in overlying strata. The heat engendered, and causing the metamorphism, may be so great as to reduce the rock subjected to it to a plastic condition, and make granite, or some other granite-like rock ; in which case granite might be made to fill opened fissures, like a true igneous rock, or to constitute the core of a long mountain range, like that of the Sierra Nevada. 9. The region of a Synclinorium becomes added to the stable part of the Continent The region that had been long under- going subsidence becomes, after the upturning and consolida- 15 V DYNAMICAL GEOLOGY. tion, stiff, unyielding, and stable ; and the locus of the next progressing geosynclinal on the same continental border will be situated to one or the other side of it. After the Alle- ghany range was made, there was, in the next or Triassic pe- riod, a new trough, or rather a series of them, more to the eastward, in which the Triassico-Jurassic beds were laid down. 10. Geanticlinals as well as Geosynclinals concerned in Moun- tain-making. In the movements of the earth's crust there would necessarily be upward as well as downward flexures, that is, geanticlinals as well as geosynclinals. The Appa- lachians, as explained above, may, when first made, have stood up in lofty ridges, without having undergone any uplifting from an elevation of the crust underneath. But, however this be, the region actually experienced elevation before the Triassic period opened, as is proved by the position of the Triassic beds ; and this took place through a gentle upward bending of the crust, such a bending becoming possible after (although not before) the region of the Appalachians had become a portion of the stable part of the continent. The Rocky Mountains in the Cretaceous era were 10,000 feet below their present level, the sea covering them. They were raised as a whole, during the Tertiary, through a low geanticlinal. The last geosynclinals were more local than the preceding, because the crust had become stiffened by its pli- cated and solidified, and partly crystallized, coatings, as well as by thickening beneath ; and, therefore, while the Tertiary movements were in progress, the part of the force not ex- pended in producing them carried forward an upward bend, or geanticlinal, of the vast Rocky Mountain region as a whole. 11. Anticlinoria of the Atlantic Border of North America, - An upward bend of the crust, or geanticlinal, is of itself an elevation; and such an elevation is* an anticlinorium. The Cincinnati uplift, described on page 91, is an anticlinorium, made, parallel with the Appalachians, after the Lower Silu- rian era, contemporaneously with the making of the Green Mountains. RESULTS OF THE EARTH'S CONTRACTION. 339 While the geosynclinal preparatory for the making of the Appalachians and those for the Triassico-Jurassic formations were going forward, through Paleozoic and Mesozoic time, there was, along the Atlantic Border, near or outside of the present coast-line a geanticlinal in progress, or sea-border an- ticlinorium. It was the first effect of the pressure from the ocean- ward ; and the geosynclinal was the second. Proofs of this are found (1) in the necessity that one move- ment should have taken place as a counterpart to the other, since the depression of a geosynclinal thousands of feet would push out from beneath it an equivalent mass of plastic rock ; and this would involve a bulging on one side or the other ; (2) in the fact that obliquely upward pressure from the ocean- ward, however slight the obliquity, would first have made an upward bend, and beyond this the downward bend ; and (3) in the character of the remains of marine life, or else its ab- sence, in the sea-border rocks, through a large part of Paleo- zoic and Mesozoic time, showing that a barrier of some kind existed along the sea-border. The facts from the fossils are these : While, in the early part of the Lower Silurian, the species of the Eastern border are like those of Europe in some points, this is not so in the long Trenton period, so that the barrier must then have ex- isted. In the Carboniferous rocks of Eastern Pennsylvania there are almost no marine fossils; and again, in those of the following Triassic and Jurassic eras, none at all. It was not until the Cretaceous period that the coast was open to the ocean, through a disappearance of the geanticlinal barrier. The Cretaceous rocks abound in marine fossils. Anticlinoria appear generally to have faded out, as gravity was against their permanence ; and that in the region of Cin- cinnati, extending southwestward to Tennessee, is one of the few permanent ones. 12. Geanticlinal effects over the Continents greatest and most permanent, and Geosynclinal least so, in the Tertiary and Quater- nary Ages. After the crust had become thickened, by the 340 DYNAMICAL GEOLOGY. earth's internal cooling, through the ages, and had been stiff- ened also by the plication and solidification, and partly the crystallization, of the strata of the supercrust, geosynclinals became less a possibility, and therefore of diminished extent ; and consequently the chief movement caused by the ever- continuing lateral pressure was an upward one. Hence it is that the mountain-chains received their great height so largely in the Tertiary ; and hence also the vastness of the areas over the earth's surface that were affected by single movements, such as the high-latitude movements of the Quaternary. There was, also, a downward bending over those higher lati- tudes, in the Quaternary, and another in the warm parts of the oceans, the coral-island subsidence. But these bear the character of the times in the extent of surface involved, and are wholly unlike the mountain-making geosynclinals of ear- lier time. It is probable that the Pacific coral-island subsi- dence, or geosynclinal, was the counterpart of the geanticlinals over the continents of the later Tertiary and early Quater- nary. 13. Fractures and outflows of igneous rocks become numerous, after the crust has become too much stiffened to bend easily. Great floods of doleryte and trachyte were poured out over the Eocky Mountain slope, after the close of the Cretaceous pe- riod. The previous plications and solidifications of the strata involved in the making of the various ranges of mountains - the Sierra Nevada and the Coast ranges on the west, and the Wahsatch and Cretaceous mountains on the east had left the crust firm and unyielding ; and, being too stiff to bend, it broke, and out leaped the fiery floods. It had broken at times before; but at this time the fractures became much more numerous, and the floods of rock more extensive. Moreover, from this era appears to date the opening of the great volcanoes of the Shasta range. In fact, the larger part of the volcanic eruptions of the world are probably of Tertiary and later origin. Fractures giving outlet to igneous eruptions have probably RESULTS OF THE EARTH'S CONTRACTION. 341 been, in all cases, consequences either (1) of catastrophe in a geosynclinal, as in the Triassico- Jurassic areas of the Atlantic border, or (2) catastrophe in a geanticlinal, when the crust was too stiff for geosynclinal bendings, as over the Pacific slope of the Rocky Mountains ; and the latter became far the most common in the later part of geological time. The principles in the earth's evolution above presented have been elucidated by reference mainly to facts from North America. If true for that continent, the same must be law for all continents.* 14. Mountain-making slow work. To obtain an adequate idea of the way in which lateral pressure has worked, it is necessary to remember that mountain elevation has taken place after immensely long periods of quiet and gentle oscil- lations. After the beginning of the Primordial, the first period of disturbance in North America, of special note, was that at the close of the Lower Silurian, in which the Green Mountains were finished ; and if time, from the beginning of the Silurian to the present, included only 48 millions of years (page 245), the interval between the beginning of the Primordial and the uplifts and metamorphism of the Green Mountains was at least 20 millions of years. The next epoch of moun- tain-making on the Atlantic border was after the Devonian in Nova Scotia and New Brunswick ; on the above basis, it occurred 30 millions of years from the beginning of the Primordial. The next epoch of disturbance was that at the close of the Carboniferous era, in which the Alleghanies were folded up ; by the above estimate of the length of time, 36 millions of years after the commencement of the Silurian; so that the Alleghanies were at least 36,000,000 of years in making, the preparatory subsidence having be- gun as early as the beginning of the Silurian. The next on the Atlantic border was that of the displacements of the * For a fuller discussion of the subject here briefly presented, see a memoir in the American Journal of Science for June, July, August, and September, 1873, Vols. V. and VI. 342 CONCLUSION. Triassico-Jurassic sandstone, and the accompanying igneous ejections, which occurred before the Cretaceous era, at least 5 millions of years, on the above estimate of the length of time, after the Appalachian revolution. Thus the lateral pressure resulting from the earth's contraction required an exceedingly long time, in order to accumulate force sufficient to produce a general yielding and plication or displacement of the beds, and start off a new range of prominent elevations over the earth's crust. CONCLUDING REMARKS. Geology may seem to be audacious in its attempts to unveil the mysteries of creation. Yet what it reveals are only some of the methods by which the Creator has performed his will ; and many deeper mysteries it leaves untouched. It brings to view a perfect and harmonious system of life, but affords no explanation of the origin of life, or of any of nature's forces. It accounts for the forms of continents ; but it tells nothing* as to the source of that arrangement of the wide and narrow continents and wide and narrow oceans that was necessary to the grand result. It teaches that strata were made in many successions as the continents lay balancing near the water's level, sometimes just above the surface, sometimes a little below ; but it does not explain how it happened that the amount of water was of exactly the right quantity to fill the great basin, and admit of oscillations of the land beneath or above its surface by only small changes of level ; for if the water had been a few hun- dred feet below the level it now has, the continents would have remained mostly without their marine strata, and the plan of progress would have proved a failure ; or if as much above its present level, the land through the earlier ages would have been sunk to depths comparatively lifeless, with no less fatal results both to the series of rocks and the system of CONCLUSION. 343 marine and terrestrial life ; and in the end there would have been broad and narrow strips of dry land and archipelagoes, in place of the expanded Orient and Occident. It may be said to have searched out the mode of develop- ment of a world. Yet it can point to no physical cause of that prophecy of Man which runs through the whole history ; which was uttered by the winds and waves at their work over the sands, by the rocks in each movement of the earth's crust, and by every living thing in the long succession, until Man appeared to make the mysterious announcements intelligible. For the body of Man was not made more completely for the service of the soul, than the earth, in all its arrangements from beginning to end, for the spiritual being that w r as to occupy it. In Man, the bones are not merely the jointed framework of an animal, but a framework shaped throughout with reference to that erect structure which befits and can best serve Man's spiritual nature. The feet are not the clasping and climbing feet of a monkey ; they are so made as to give firmness to the tread and dignity to the bearing of the being made in God's image. The hands have that fashioning of the palm, fingers, and thumb, and that delicacy of the sense of touch, which adapt them not only to feed the mouth, but to contribute to the wants of the soul and obey its promptings. The arms are not for strength alone, for they are weaker than in many a brute, but to give the greater power and expression to the thoughts that issue from within. The face, with its expressive features, is formed so as to re- spond not solely to the emotions of pleasure and pain, but to shades of sentiment and interacting sympathies the most varied, high as heaven and low as earth, ay, lower, in de- based human nature. And the whole being, body, limbs, and head, with eyes lo'oking, not toward the earth, but beyond an infinite horizon, is a majestic expression of the divine feature in Man, and of the infinitude of his aspirations. So with the earth, Man's world-body. Its rocks were so arranged, in their formation, that they should best serve Man's 344 CONCLUSION. purposes. The strata were subjected to metamorphism, and so crystallized that he might be provided with the most per- fect material for his art, his statues, temples, and dwellings ; at the same time they were filled with veins, in order to supply him with gold and silver and other treasures. The rocks were also made to enclose abundant beds of coal and iron ore, that Man might have fuel for his hearths and iron for his utensils and machinery. Mountains were raised to temper hot climates, to diversify the earth's productiveness, and, pre-eminently, to gather the clouds into river-channels, thence to moisten the fields for agriculture, afford facilities for travel, and supply the world with springs and fountains. The continents were clustered mostly in one hemisphere to bring the nations into closer union ; and the two having climates and resources the best for human progress, the northern Orient and Occident, were separated by a narrow ocean, that the great mountains might be on the remoter bor- ders of each, and all the declivities, plains, and rivers be turned toward one common channel of intercourse. So, also, the species of life, both of plants and animals, were appointed to administer to Man's necessities, moral as well as physical. Besides these beneficent provisions, the forces and laws of nature were particularly adapted to Man, and Man to those laws, so that he should be able to take the oceans, rivers, and winds into his service, and even the more subtle agencies, heat, light, and electricity ; and the adjustments were made with such precision that the face of the earth is actually fitted hardly less than his own to respond to his inner being : the mountains to his sense of the sublime, the landscape, with its slopes, its trees, its flowers, to his love of the beautiful, and the thousands of living species, in their diversity, to his various emotions and sentiments. The whole wo*rld, indeed, seems to have been made almost a material manifestation, in multi- tudinous forms, of the elements of his own spiritual nature, that it might thereby give wings to the soul in its heavenward aspirings. It may therefore be said with truth that Man's CONCLUSION. 345 spirit was considered in the ordering of the earth's structure as well as in that of his own body. It is hence obvious that the earth's history, which it is the object of Geology to teach, is the true introduction to human history. It is also certain that science, whatever it may accomplish in the discovery of causes or methods of progress, can take no steps toward setting aside a Creator. Far from such a result, it clearly proves that there has been not only an omnipotent hand to create, and to sustain physical forces in action, but an all- wise and beneficent Spirit to shape all events toward a spiritual end. Man may well feel exalted to find that he was the final purpose when the word went forth in the beginning, LET LIGHT BE. And he may thence derive direct personal assur- ance that all this magnificent preparation is yet to have a higher fulfilment in a future of spiritual life. This assurance from nature may seem feeble. Yet it is at least sufficient to strengthen faith in that Book of books in which the promise of that life and " the way " are plainly set forth. 15* APPENDIX. A. Catalogue of American Localities of Fossils. THE following catalogue of American localities of fossils contains only some of the more important, and is intended for the conven- ience especially of the student-collector. Localities of Fossils. Acadian Group. Coldbrook, Ratcliffe's Millstream, St. John, New Brunswick. Long Arm of Canada Bay, Newfoundland. Potsdam Group. Swanton, Vt. Braintree, Mass. Keeseville (at "High Bridge"), Alexandria, Troy, N. Y. Chiques Ridge, Pa. Falls of St. Croix, Osceola Mills, Trempaleau, Wisconsin. Lansing, Iowa. S*t. Ann's, Isle Perrot, C. W. Near Beauharnois on Lake St. Louis, C. E. Calciferous. Mingan Islands, St. Timothy, and near Beauharnois, C. E. Grand Trunk Railway between Brockville and Prescott, St. Ann's, Isle Perrot, C. W. Amsterdam, Fort Plain, Canajoharie, Chazy, Lafarge- ville, Ogdenshurg, N. Y. Quebec Group. Mingan Islands, Point Levi, Philipsburg, and near Beauharnois, C. E. Point Rich, Cow Head, Newfoundland. Cuts in Black Oak Ridge and Copper Ridge, Knoxville and Ohio Railroad, Tenn. Malade City, Idaho. Chazy Limestone. Chazy, Gal way, Westport, N. Y. One to three miles north of "the Mountain" Island of Montreal, C. E. St. Joseph's Island, Sault Ste. Marie, C. W. Knoxville, Lenoir's, Bull's Gap, Kings- port, Tenn. Bird's-eye Limestone. Amsterdam, Little Falls, Fort Plain, Adams, Watertown, N. Y. Black River Limestone. Watertown, N. Y. Ottawa, C. W. Island of Montreal, and near Quebec, C. E. Trenton Limestone. Adams, Watertown, Boonville, Turin, Jackson- burg, Little Falls, Lowville, Middleville, Fort Plain, Trenton Falls, N. Y. Pine Grove, Aaronsburg, Potter's Fort, Milligan's Cove, Pa. Highgate APPENDIX. 347 Springs, Vt. Montmorency Falls and Beauport Quarries near Quebec, Island of Montreal (quarries north of the city), C. E. Ottawa, Belleville, Trenton (G. T. R. R., west of Kingston), C. W. Copper Bay, Mich. El- kader Mills, Turkey River, Dubuque, Iowa. Falls of St. Anthony, St. Paul, Mineral Point, Cassville, Beloit, Quimby's Mills near Benton, Wis. Warren, Rockton, "Winslow, Dixon, Freeport, Cedarville, Savanna, Rockford, 111. Murfreesborough, Columbia, Lebanon, Tenn. Utica Slate. Turin, Martinsburg, Lorraine, Worth, Utica, Cold Spring, Oxtungo and Osquago Creeks near Fort Plain, Mohawk, Rouse's Point, N. Y. Rideau River along railroad at Ottawa, bed of river two miles above, C. W. Cincinnati Group. Pulaski, Rome, Lorraine, Boonville, N. Y. Penn's Valley, Milligan's Cove, Pa. Oxford, Cincinnati, Lebanon, 0. Madison, Richmond, Ind. Anticosti, opposite Three Rivers, C. E. Weston on the Humber River, nine miles west of Toronto, C. W. Little Makoqueta River, Iowa. Savannah, Green Bay, Wis. Thebes, Alexander County ; Savanna, Carroll County ; Scales's Mound, Jo Daviess County ; Oswego, Yorkville, Kendall County ; Naperville, Dupage County ; Wilming- ton, Will County, 111. Cape Girardeau, Mo. Drummond's Island, Mich. Nashville, Columbia, Knoxville, Tenn. Medina Sandstone. Lockport, Lewiston, Medina, Rochester, N. Y. Long Narrows below Lewistown, Pa. Dun das, C. W. Clinton Group. Lewiston, Lockport, Reynolds Basin, Brockport, Roch- ester, Wolcott, New Hartford, N. Y. Thorold on Welland Canal, Hamilton, Ancaster, Dundas, C. W. Hanover, Ind. Niagara. Lewiston, Lockport, Gosport, Rochester, Wolcott, N. Y. Thorold, Hamilton, Ancaster, C. W. Anticosti, C. E. Arisaig, Nova Scotia. Racine, Waukesha, Wis. Sterling, Grafton, Savanna, Chicago, Joliet, 111. Marblehead on Drummond's Island, Michigan. Springfield, Cedarville, Ohio. Delphi, Waldron, Jeffersonville, Madison, Logansport, Peru, Ind. Louisville, Ky. The "glades " of West Tennessee. (Coral- line Limestone. Schoharie, N. Y.) Onondaga Salt Group. Buffalo, Williamsville, Waterville, Jerusalem Hill (Herkimer County), N. Y. Gait, Guelph (G. T. R. R.), C. W. Lower Helderberg Limestones. Dry Hill, Jerusalem Hill (Herki- mer County), Sharon, East Cobleskill, Judd's Falls, Cherry Valley, Carlisle, Schoharie, Clarksville, Athens, N. Y. Pembroke, Parlin Pond, Me. Gaspe, C. E. Arisaig, East River, Nova Scotia. Peach Point, opposite Gibraltar, Ohio. Thebes, Devil's Backbone, 111. Bailey's Landing, Mo. " Glades " of Wayne and Hardin Counties, Tenn. Oriskany Sandstone. Oriskany, Vienna, Carlisle, Schoharie, Pucker Street, Catskill Mountains, N. Y. Cumberland, Md. Moorestown and Frankstown, Pa. Bald Bluffs, Jackson County, 111. Four miles S. W. of St. Mary's, Ste. Genevieve County, Mo. Cauda-galli Grit. Schoharie (Fucoides Cauda-galli), N. Y. Schoharie Grit. Schoharie, Cherry Valley, N. Y. Upper Helderberg Limestones. Black Rock, Buffalo, Williamsville, 348 APPENDIX. Lancaster, Clarence Hollow, Stafford, Le Roy, Caledonia, Mendon, Auburn, Onondaga, Cassville, Babcock's Hill, Schoharie, Cherry Valley, Clarksville, 1ST. Y. Port Colborne, and near Cayuga, C. W. Columbus, Delaware, White Sulphur Springs, Sandusky, Ohio. Mackinac, Little Traverse Bay, Dundee, Monguagon, Mich. North Vernon, Charlestown, Kent, Hanover, Jefferson ville, Ind. Louisville, Ky. Marcellus Shales. Lake Erie shore, ten miles S. of Buffalo, Lancaster, Alden, Avon, Leroy, Marcellus, Manlius, Cherry Valley, N. Y. Hamilton Group. Lake Erie shore, Eighteen Mile Creek, Hamburg, Alden, Darien, York, Moscow, East Bethany, Bloomfield, Bristol, Seneca Lake, Cayuga Lake, Skaneateles Lake, Moravia, Pompey, Cazenovia, Delphi, Bridgewater, Richland, Cherry Valley, Seward, Westford, Milford, Portland- ville, N. Y. Widder Station (G. T. R. R.), near Port Sarnia, C. W. New Buffalo, Independence, Rockford, Iowa. Devil's Bake Oven, Jackson County, Moline, Rock Island, 111. Grand Tower, Mo. Thunder Bay, Little Traverse Bay, Mich. Jefferson ville, Ind. Nictaux, Bear River, Moose River, Nova Scotia. Geiiesee Shale. Banks of Seneca and Cayuga Lakes, Lodi Falls, Mount Morris, two miles south of Big Stream Point, Yates County, N. Y. (Genesee or Portage. Delaware, Ohio. Rockford, North Vernon, Ind. Danville, Ky.) Portage Group. Eighteen Mile Creek on Lake Erie, Chautauqua Lake, Genesee River at Portage, Flint Creek, Cashaqua Creek, Nunda, Seneca and Cayuga Lakes, N. Y. Chemung Group. Rockville, Philipsburg, Jasper, Greene, Chemung. Narrows, Troopsville, Elmira, Ithaca, Waverly, Hector, Enfield, Franklin, N. Y. - Gaspe, C. E. Catskill Group. Fossils rare. Richmond's quarry above Mount Up- ton on the Unadilla, Oneonta, Oxford, Steuben County, south of the Canis- teo, N. Y. Subcarboniferous. Burlington, Keokuk, Columbus, Iowa. Quincy, Warsaw, Alton, Kaskaskia, Chester, 111. Crawfordsville, Greencastle, Bloomington, Spergen Hill, New Providence, Ind. Hannibal, St. Genevieve, St. Louis, Mo. Willow Creek, Battle Creek, Marshal, Moscow, Jonesville, Holland, Grand Rapids, Mich. Mauch Chunk, Pa. Newtonville, Ohio. Ice's Ferry, on Cheat River, Monongalia County, W. Va. Red Sulphur Springs, Pittsburg Landing, White's Creek Springs, Waynesville, Cowan, Tenn. Big Bear and Little Bear Creeks, Big Crippled Deer Creek, Miss. Clarksville, Huntsville, Ala. Windsor, Horton, Nova Scotia. Carboniferous. South Joggins, Pictou, Sydney, Nova Scotia. Wilkes- barre, Shamokin, Tamaqua, Pottsville, Minersville, Tremont, Greensburg, Carbondale, Port Carbon, Lehigh, Trevorton, Johnstown, Pittsburg, Pa. Pomeroy, Marietta, Zanesville, Cuyahoga Falls, Athens, Yellow Creek, Ohio. Charlestown, Clarksburg, Kanawha, Salines, Wheeling, W. Va. Saline Company's Mines, Gallatin County ; Carlinville, Hodges Creek, Macoupin County ;. Colchester, McDonough County; Duquoin, Perry County; Mur- APPENDIX. 349 physborough, Jackson County ; Lasalle ; Morris, Mazon, and Waupecan Creeks, Grundy County ; Danville, Pettys' Ford, Vermilion County ; Paris, Edgar County ; Springfield, 111. Perrysville, Eugene, Newport, Horseshoe of Little Vermillion, Verniilliori County ; Durkee's Ferry, near Terre Haute, Vigo County ; Lodi, Parke County ; Merom, Sullivan County, Ind. Bell's, Casey's, and Union Mines, Crittenden County ; Hawesville and Lewisport, Hancock County ; Breckenridge, Giger's Hill, Mulford's Mines, and Thompson's Mine, Union County ; Providence and Madisonville, Hopkin's County ; Bonhar- bour, Daviess County, Ky. Muscatine, Alpine Dam, Iowa. Leavenworth, Indian Creek, Grasshopper Creek, Juniata, Manhattan, Kansas. Rockwood, Emory Mines, Coal Creek, Careyville, Tenn. Tuscaloosa, Ala. Triassic. Southbury, Middlefield, Portland, Conn. Turner's Falls, Sunderland, Mass. Phcenixville, Pa. Richmond, Va. Deep River and Dan River Coal-fields, N. C. Cretaceous. Upper Freehold, Middletown, Marlborough, Blue Ball, Monmouth County ; Pemberton, Vincenton, Burlington County ; Black- woodtown, Camden County ; Mullica Hill, Gloucester County ; Woods- town, Mannington, Salem County ; New Egypt, Ocean County, N. J. Warren's Mill, Itawamba County ; Tishomingo Creek, R. R, cuts, Hare's Mill, Carrollsville, Tishomingo County ; Plymouth Bluff, Lowndes County ; Cha walla Station (M. & C. R. R.), Ripley, Tippah County ; Noxubee, Macon, Noxubee County ; Kemper, Pontotoc and Chickasaw Counties, Miss. Finch's Ferry, Prairie Bluff, on Alabama River ; Choc taw Bluff, on Black Warrior River ; Greene, Marengo, and Lowndes Counties, Ala. Fox Hills, Sage Creek, Long Lake, Great Bend, Cheyenne River, etc., Nebraska. Fort Harker, Fort Hayes, Fort Wallace, Kansas. Fort Lyon, Santa Fe, New Mexico. Eocene. Everywhere in Tippah County ; Yockeney River ; New Pros- pect P. 0., Winston County ; Marion, Lauderdale County ; Enterprise, Clarke County ; Jackson, Satartia, Yazoo County ; Homewood, Scott County ; Chickasawhay River, Clarke County ; Winchester, Red Bluff Station, Wayne County ; Vicksburg, Amsterdam, Brownsville, Warren County ; Brandon, Byram Station, Rankin County ; Paulding, Jasper County, Miss. Clai- borne, Monroe County ; St. Stephen's, Washington County, Ala. Charles- ton, S. C. Tampa Bay, Florida. Fort Washington, Fort Marlborough, Piscataway, Md. Marlbourne, Va. Brandon, Vt. In New Jersey, at Farmingdale, Squankum and Shark River, Monmouth Co. Green River, Fort Bridger, Wyoming. Canada de las Uvas, Cal. Miocene. Gay Head, Martha's Vineyard, Mass. Shiloh, Jericho, Cumberland County, and Deal, Monmouth County, N. J. St. Mary's, Eas- ton, Md. Yorktown, Suffolk, Smithfield, Richmond, Petersburg, Va. Astoria, Willamette Valley, John Day Valley, Oregon. San Pablo Bay, Ocoya Creek, San Diego, Monterey, San Joaquin and Tulare Valleys, Cal. White River, Upper Missouri Region. Crow Creek, Colorado. Pliocene. Ashley and Santee Rivers, Si C. Platte and Niobrara Rivers, Upper Missouri. John Day Valley, Oregon. Sinker Creek, Idaho. Alameda County, Cal. 350 APPENDIX. B. Geological Implements, Specimens, etc. 1. Implements. The student requires for his geological excur- sions and research the following implements : (1.) A. hammer. If his object is to get specimens of hard rocks, or obtain minerals from such rocks, it should have the form in Fig. 406, the edge being in the direction of the handle. But if fossils are to be collected, this edge should be transverse to the handle. The face should Fi S* 4 06. be flat, and nearly square, with its edges sharp instead of rounded. The socket for the handle should be large, that the handle may be strong. The hammer, for ordinary excursions, should weigh 1^ pounds exclusive of the handle ; the handle should be about 12 inches long. Another is required for trimming specimens, weighing half a pound. (2.) A steel chisel, 6 inches long, such as is used by stone- cutters. Also, another half this size. (3.) A clinometer, with magnetic needle attached. The best kind is a clinometer-compass 3 inches in diameter, having a square base about 3^ inches each side, two sides of the base being parallel to the north and south line of the compass. (4.) A small magnet. A magnetized blade of a pocket-knife is a good substitute. (5.) A measuring-tape 50 feet long. The field geologist should know ac- curately the measurements of his own body, his height, length of limbs, step or pace, that he may use himself, whenever needed, as a measuring-rod. (6. ) In many cases, a pick, a crow-bar, a sledge-hammer of 4 to 8 pounds' weight, and the means of blasting, are necessary. (7.) Besides the above, a barometer and surveyor's instruments are occa- sionally required. Of the latter, a hand-level is a desirable instrument for determining small elevations by levelling ; it is a simple brass tube, with cross-hairs, bubble, and mirror. A first-rate aneroid barometer is excellent for all heights between 5 feet and 2,000 feet ; and, having one, the hand- level is superfluous. 2. Specimens. Specimens for illustrating the kinds of rocks should be carefully trimmed by chipping to a uniform size, pre- viously determined upon : 3 inches by 4 across, and 1 inch through, is the size commonly adopted. In the best collections of rocks, the angles are squared and the edges made straight with great precision. They should have a fresh surface of fracture, with no bruises by the hammer. It is often well to leave one side in its natural weathered state, to show the eifects of weathering. Specimens of fossils will, of course, vary in size with the nature APPENDIX. 351 of the fossil. When possible, the fossil should be separated from the rock ; but this must be done with precaution, lest it be broken in the process; it should not be attempted unless the chances are strongly in favor of securing the specimen entire. The skilful use of a small chisel and hammer will often expose to view nearly all of a fossil when it is not best wholly to detach it. "When the fossils in a limestone are silicified (a fact easily proved by their scratching glass readily and their undergoing no change in heated acid), they may be cleaned by putting them into an acid, and also applying heat very gently, if effervescence does not take place without it. The best acid is chlorohydric (muriatic) diluted one half with water. Collections both of rocks and fossils should always be made from rocks in place, and not from stray bowlders of uncertain origin. 3. Packing. For packing, each specimen should be enveloped separately in two or three thicknesses of strong wrapping-paper. This is best done by cutting the paper of such a size that when folded around the specimen the ends will project two inches (more or less, according to the size of the specimen) ; after folding the paper around it, turn in the projecting ends (as the end of the finger of a glove may be turned in), and the envelope will need no other securing. Pack in a strong box, pressing each specimen, after thus enveloping it, firmly into its place, crowding wads of paper between them wherever possible, and make the box absolutely full to the very top (by packing-material if the specimens do not suffice), so that no amount of rough usage by wagon or cars on a journey of a thousand miles would cause the least movement inside. 4. Labelling. A label should be put inside of each envelope, separated from the specimen by a thickness or more of the paper. The label should give the precise locality of the specimen, and the particular stratum from which taken, if there is a series of strata at the place ; it should also have a number on it corresponding to a number in a note-book, where fuller notes of each are kept, together with the details of stratification, strike, and dip, sections, plans, changes or variations in the rocks, and all geological observations that may be made in the region. A specimen of rock or fossil of unknown or uncertain locality is of very little value. 352 APPENDIX. 5. Note-Book. The note-book should have a stiff leather cover, and be made of rather thick, smooth writing-paper, good for sketch- ing as well as for writing. Five inches by three and a half is a convenient size. A kind made of prepared paper, and provided with a zinc-pointed pencil, is often sold for the purpose, and is excellent until it gets perchance a fall into the water, when the notes that may have been carefully made will be pretty surely obliterated. If the geologist is a draughtsman, he may also need a portfolio for carrying larger paper ; but the small note-book will, in general, answer every purpose. INDEX. NOTE The asterisk after the number of a page indicates that the subject referred to is illustrated by a figure. Acadian group, 80. Acalephs, 57,* 58. Acanthoteuthis, 172.* Acephals, 56.* Acrodus minimus, 52.* nobilis, 52.* Acrogens , 60. Carboniferous, 125. Devonian, 106. Actinia, 57.* Actinocrinus proboscidialis, 129.* .SSpyornis, extinction of, 243. Ages in Geology, 64, 65. Alabama period, 203, 204. Albite, 16. Algse, 60. Alleghany coal-area, 115. Alluvial deposits, 226, 283 Alps, glaciers in, 300. America, North, Geography of. See GEOGRAPHY. Ammonites, 170.* Huniphreysianus, 170.* Jason, 170.* placenta, 191.* tornatus, 171 * ofMesozoic, 198. Amphibians, 50, 165,* 174.* Amphipods, 54 * Aiuphitherium, 179 * Amygdaloid, 318. Anatifa, 54.* Anchitherium,213.* Andalusite, 17.* Angiosperms, 62. Cretaceous, 186.* Tertiary, 206.* Animal kingdom, 47, 48. Anisopus, tracks of, 166.* Anogens, 60. Ant-eaters, 216. Anthracite, 18, 121. origin of, 156. vegetable tissues in, 134.* Anticlinal, 42.* Anticlinorium, 338. Appalachian revolution, 155. Appalachians, formation of, 151,248,334 folded rocks of, 152.* thickness of formations of, 104, 151. Araucariae , 62. Archaean time, 65, 73. N. America, 73 * Archaeoniscus Brodiei, 173.* Archaeopteryx, 178. Archimedes reversa, 129 * Arctic coal area, 117. Arenicola piscatorum, 54.* Argillyte, 24. Artesian wells, 285.* Arthrolycosa, 130.* Articulates, 49, 53,* 81.* Asaphus gigas, 88.* Ascidians, 54. Astarte Conradi, 208 * Athyris subtilita, 129.* Atmosphere, agency of, 273. Atolls, 269.* Atrypa aspera, 110.* Auk, extinction of, 243 Aulopora cornuta, 109.* Australia, basaltic columns of, 319.* Marsupials of, in Quater- nary, 230. Avicula emacerata, 96.* Trentonensis, 88.* Azoic. See ARCELEAN. Baculites ovatus, 191.* Bagshot beds, 206. Bala formation, 86. Basalt, 26, 311. Basaltic columns, 35,* 319.* Bathygnathus borealis, 166.* Beach-formations, 32, 292. Bear, cave, 233. Beetles, 130. Belemnitella mucronata, 191.* Belemnites,171,*191.* Belodon priscus, 166.* Bembridge beds, 206. Bernese Alps, 296. Bilin, infusorial bed of, 208. Birds, 50. Cretaceous, 194. of Connecticut Valley, 167* ofSolenhofen,178, 201. Tertiary, 210. Birdseye limestone, 85 Bituminous coal, 18, 121. Black River limestone, 85. Black slate of Devonian, 104. Bore, 289. Bowlders, 220, 221, 282, 298. Brachiopods, 56 * 88* 96 * 98,* 129.* Brandon fossil fruits, 206.* Breccia, 23. Brown coal, 18. Bryozoans, 57.* Buhrstone. Tertiary, 205. Bunter Sandstein, 166. Buprestis, 173.* Catamites, 107, 125.* in Triassic, 167. Calamopsis Dana-, 207 * Calcareous rocks, 22, 25. Calciferous sand-rock, 85. Calcite, 19.* Callista Sayana, 209 * Callocystites Jewettii, 57 * Calymene Blumenbachii, 54 * 89. Cambrian, 81. Camel, Tertiary American, 214. Canadian period, 84. Cancer, 54.* Canons, 278.* Caradoc sandstone, 86. Carbon, 18. Carbonate of lime, 19. Carbonic acid, 18. Carboniferous age, 114. Carcharodon angustidens,52.* megalodon, 209. Cardita planicosta, 208.* Caryocrinus ornatus, 96 * Catbpterus gracilis, 165.* W 354 INDEX. Catskill period, 105. Connecticut River sandstone Dikes, 30,* 318 Cauda-galli grit, 103. and footprints, 159. Dicotyledons, 62. Cave animals of Quaternary, terraces, 227.* Dinoceras, 213.* 233. Cenozoic time, 201. trap rocks, 160. Continents, basin-like shape Dinornis, extinction of, 242. Dinosaurs, 176,210. general observations on, of, 9.* Dinothere, 215.* 243. origin of, 330.* Dioryte, 26. Cephalaspis, 112.* Contraction a cause of change Dip, 40.* Cephalates, 55.* of level, 327. D.protodon,236. Cephalization, progress in, Coprolites, 177. Dipterus, 112.* 258. Coral islands, 268.* Discina, 252. Cephalopods, 55.* ofMesozoic,200. Cestracionts, 52,* 113, 173. reef of the Devonian, 103. Corals, formation of, 58. recent, 57.* Dislocated strata, 39.* Dodo, extinction of, 241. Doleryte, 26, 317. Chsetetes lycoperdon, 87.* Coralline crag, 206. Dolomite, 19. Chain-coral, 9ti.* Corniferous limestone, 103. Drift, 220. Chaik, 185, 195. period, 103. sands, 32,* 274. Champlain period, 220, 225. Crabs, 53.* scratches, 221.* Chazy limestone, 85. Cheirolepis Traillii, 51. Crassateila alta, 208.* Craters, 307. Dromatherium sylvestre, 1G8.* Dudley limestone, 95. Cheirotherium, 174.* Crepidula costata, 209.* Dunes, 274. Chemung period, 1U4. Chlorite slate, 24. Cretaceous period, 159, 184. America, map of, 194. Dynamical Geology, 264. Chonetes mesoloba, 129.* Crevasses, 296. Eagre, 289. setigera, 110.* Cidaris Blumenbachii, 168.* Crinoidal limestone, Subcar- boniferous, 119. Earth, size and features of, 5. relation to Man, 343. Cinders, 308. Crinoids, 58.* features, origin of, 327. Cinnamomum, Tertiary, 207.* Jurassic, 168.* interior of, 328. Circumdenudation, 279. Primordial. 82.* Earthquakes, origin of, 327, Clathropteris, 163.* Silurian, 88,* 97.* 329. Clay, 20. Subcarboniferous, 128.* Ebb-and-flow structure, 32. Clay -slate, 24. Crocodiles, 193. Echini, 57.* Cleavage, slaty, 36.* Crustaceans, 53.* Mesozoic, 174.* Cliff-limestone, 104. Cryptogams, 60. Echinoderms, 57.* Climate, cause of changes in, Crystalline rocks, 20. Edentates, Quaternary, 235.* 330. Crystallization. See METAMOR- Elephants, Quaternary, 234, Carboniferous, 136. PHISH. 235. Cretaceous, 195. Ctenacanthus major, 131.* Tertiary, 215. Jurassic, 183. Paleozoic, 147. Ctenoids, 50.* Currents, oceanic, 289, 290. Elephas primigenius, 234, 239.*- Eievation of coast of Sweden, Quaternary, 237. Cyathophylloid corals, 58, 87 * 232. Tertiary, 219. 96,* 109.* of Green Mountains, 90. Clinkstone. See PHONOLYTE. Cyathophy Hum rugosum , of Himalayas, 218. Clinometer, 40.* 109.* of Rocky Mountains, 217. Clinton group, 93. Cycads, 62. of Western South America, Coal, kinds of, 18. Triassic and Jurassic ,162.* 219. formation of, 133. Cycloids, 50. of Quaternary , 216. deprived of bitumen, 155. Coal-areas of Britain and Eu- Cyclonema cancellata, 96.* Cyclopteris linnaeifolia, 163.* Elevations, causes of, 327. Emery, 15. rope, 117.* -areas of N. America, 115.* Halliana, 106. Cypris, 53. 193. -beds, characters of, 120. Cystideans,58,*97. Encrinus liliiformis,57,* 168.* -beds, formation of, 135. Cythere Americana, 54.* Endogens, 63 -beds of Triassic, 164. England, geological map of, -beds, flexures in, 152.* Decapods, 53.* 118.* -formation, rocks of, 119. Delta of Mississippi, 283.* Entomostracans, 53.* -plants of Richmond, 1*59.* Deltas, 284. Eocene, 202. -plants of the Carbonifer- Dendrophyllia, 57.* Eosaurus Acadianus, 132 * ous, 123.* Coccoliths, 61. Denudation, 43,* 276, 280. Desmids, 61,* 108.* Eoscorpius carbonarius, 130.* Kozoon, 77.* Coccosteus, 111.* Detritus, 282. Ephemera, 165- Cockroaches, 130. Devonian age, 103. Equiseta, 60, 107, 127. Coin-conglomerate, 240.* hornstone, microscopic or- Equivalent strata, 44. Colorado, canon of, 278.* ganisms in, 108.* Erie shale, 104. Columnaria alveolata, 87-* Diabasyte, 26, 27, 318,* 326. Erosion by rivers, 275^286. Comatulids, 58. Diamond, 18. over continents, 279.* Comprehensive types, 253. Diatoms, 61.* Eruptions of volcanoes, 309. Concretions, 34, 35.* in hornstone, 108 * non-volcanic, 317. Conformable strata, 43.* formation of deposits by, Estheria ovata, 164.* Conglomerate, 23. 186. Estuary formations. 2S4 Conifers, 62, 107, 127. Tertiary, 207. Euplectella speciosa, 188.* INDEX. 355 Eurypterus remipes, 98.* Exogyra arietina, ly> * Extermination of species, 92, 147,200,241. methods of, 265. Fagus,207.* Fan-palm, 206. Fasciolaria buccinoides, 191.* Faults, 41,* 153.* Favosites Goldfussi, 109.* Niagarensis, 96.* Feldspar, 16. Ferns, 60. Devonian, 106.* Carboniferous, 125.* Fiords, 223. Fishes, 50 * Age of, 103. Carboniferous, 130.* Devonian, 111.* Mesozoic, 173,* 192.* Silurian, 98. Teliost, 191, 192.* Fish-spines, 113,* 131 * Flags, 22. Flint, 14, 186. Flint arrow-heads, 238. Flow-and-plunge structure, 32,* 293. Fluvio-marine formations, 292 Folded rocks, 42,* 74, 153,* 327. Footprints. See TRACKS. Foraminifera, 60.* Formation, 29. Fossils, use of, in determining the equivalency of stra- ta, 3, 46. list of localities of, 346. number of species of, 102, 253. Fragmental rocks, 20, 22. Freestone of Portland, Ct., 159. Fresh waters, action of, 275. Fruits, Carboniferous, 127.* Tertiary, 206.* Fusulina, 59.* Fusus Newberryi, 193.* Ganoids, 50, 51 * Carboniferous, 131.* Devonian, 111.* Triassic, 165.* Garnet, 17 * Gasteropods, 56.* Geanticlinal, 42, 329. Genera, long-lived, 149. Genesee shale, 104. Genesis, 263. Geode, 35. Geography, progress in North America, 77, 78, 146, 246, 332. American, in Archaean, 73,* 77, 143- in Carboniferous, 137. in Cretaceous, 194 * in Devonian, 113. in Mesozoic, 196. in Paleozoic, 144. in Quaternary, 243. Geography. American, in Silu- rian, 89, 98. in Tertiary, 216.* Triassic, 180. Geosynclinal,42, 329. Geysers, 316.* Giants' Causeway, 319. Gilbert Islands, 270. Glacial period, 219, 220, 230. Glacier, great, of Switzerland, 296.* scratches, 222.* theory of the drift, 223. Glaciers, 295. Glen Roy, benches of, 229. Globigerina, 58.* Glyptodon, 236.* Gneiss, 23. Goniatites, first of, 109. last of, in Triassic, 170. Marcellensis, 110.* Grammy sia Hamiltonensis, 112.* bisulcata, 110.* Granite, 23, 26. Graphite, 18,76. Graptolites, 87.* Greenland, glaciers of, 300. changes of level in, 232. Green Mountains, emergence of, 90. limestone of, 85. Green-sand, 185. Grit, 23. Gryph8ea,speciesof,169,*190 * Guadaloupe, human skeleton of, 240.* Gulf of Mexico, progress of, 216. Gymnosperms, 62. Gypsiferous formation, 160. Gypsum, 94, 123. Gyrodus umbilicus, 51.* Halysites catenulata, 96.* Hamilton period, 104 Harmony in the life of an age, 254. Hawaii, volcanoes of, 309.* Heat, 303, 329. evidence of internal, 303 Height of Aconcagua peak , 307 of Sorata, 307. of Shasta, 307. Hempstead beds, 206. Herculaneum, 314. Heterocercal, 51 * Hipparion, 213.* Hitchcock , E. , tracks described by, 166.* Holoptychius, 112.* Homalonotus, 93.* Homocercal, 51 Hornblende, 1(3 Hornblende rocks, 24. Hornstone, 103. microscopic remains in , 108.* Horse, fossil, 212, 213.* Hot Springs, 316. Hudson Bay, 332. Hudson River shale, 86. Hyaena spelaea, 233. Hybodus, species of, 52.* Hydroid Acalephs, 58.* Hydromica slate, 24. Hyposyenyte, 24, 26. Ice of lakes and rivers, 295. glacier. 295. Icebergs, 223, 295, 300. Ichthyosaurus, 175.* Igneous rocks, 21, 26,306,340. ejections of Lake Superior region, 90 ejections, Triassic, 160. Iguanodon,176, 195. Infusorial beds, Tertiary, 208. Ink-bag, fossil, 172.* Inoceramus problematicus, 190,* 209. Insects, 53. first of, 111. Carboniferous, 130.* Jurassic, 173.* Triassic. 164.* Irish Deer, 234. Iron ore, Archaean, 74.* Iron ores, Carboniferous, 120. Iron mountains of Missouri, 74, Isopods, 54.* Itacolumyte, 25. Joints in rocks, 35, 36,* 329. Jurassic period, 159. Kerosene, 122. Keuper, 161. Keweenaw Point, 85, 90. Kilauea, 310. Kingsmill Islands, 270. Kirkdale cavern, 233. Labradorite, 16. Labyrinthodonts, 174.* Lacustrine deposits, 228. Lake Champlain in Quater- nary, 228. Mem phremagog, Devonian coral-reef of, 104. Lakes,origin of Great, 146, 247. Lake-dwellings, 240. Lamellibranchs, 56.* Laminated structure, 22, 31.* Lamna elegans, 52,* 210. Land-slides, 286. Lava, 27,308. Layer, 29. Lecanocrinus elegans, 88.* Leguminosites, 187.* Leperditia alta, 98.* Lepidodendra, 97. Lepidodendron aculeatum, 125.* primajvum, 106.* Lepidosteus osseus, 51.* Leptasna sericea, 88 * transversalis, 96 * Leptgenas, last of, 169. Lesley, results of denudation, 279.* Level, change of, in Greenland, 232. 356 INDEX. Level, changes of, in the Qua- ternary, 228, 230, 231. origin of changes of, 327. Level. See ELEVATION. Lias, 161. Libellula, 173 * Life, agency of, in rock-mak- ing, 264. general laws of progress of, 251 Life. See SPECIES. Lignite, 18, 185, 219. L gnitic period, 202, 204. Limestone, 25, 26. formation of, 143, 265, 268, 297. Limestones of Mississippi Val- ley, 141 * Limulus,53. Lingulse, 81,* 252. Lingula flags, 80. Liriodendron Meekii, 187.* Lithostrotion Canadense, 129.* Llandeilo flags, 86. Llandovery beds, 95. Localities of fossils, list of, 346. Locusts, 130. London clay, 206. Lorraine shale, 86. Lower Helderberg, 94. Ludlow group, 95. Lycopods, 60, 97, 106,* 126.* Macluerodus, 234. Madagascar, /Epyornis of, 243. Magnesian limestone, 19, 25, 85. Magnolia, 206. Mammals, 50. Age of, 202. first of, 168.* Jurassic, 179,* 201. Tertiary, 210 * Triassic, 168,* 179 Man, Age of, 201, 219, 238. fossil, of Guadaloupe, 240.* the head of the system of life, 241, 257. Map of Pennsylvania coal re- gion, 116.* of England, 118.* of N. America, Archaean, 73.* of N. America, Cretaceous, 194. of N America, Tertiary, 216* of New York and Canada, 71.* of United States, 69.* Marble, 26. of Green Mountains , 85 , 91. Marcellus shale, 104 Marine formations, 291. > Marl, 22, 185. Marlyte, 23. Marsupials, 50. Triassic, 168, 179. Jurassic, 179.* Massive structure, 22, 31.* Mastodon, QuaVrnary, 234.* Tertiary, 215. Mastodonsaurus, 174 * Mauna. See MOUM. May-flies, 130.* Medina group, 93. Medusa;, 57,* 58. Megaceros Hibernicus, 234. Megalosaur, 176.* Megathere, 235.* Mer-de-glace, 296. Mesozoic time, 157. general observations on, 193. geography of, 196. life of, 198. Metamorphic rocks, 21, 23. Metamorphism, nature and cause of, 319, 337. Miamia Bronsoni, 130.* Mica, 16. schist, 24. Michigan coal-area, 115 Microdon bellistriatus, 110 * Microscopic organisms, 59,* 61,* 108,* 267. Millepores, 58. Mineral coal. See COAL. oil, 122. Miocene, 202 Mississippi River, amount of water of, 276. delta of, 283.* detritus of, 282. Moa, extinction of, 242. Mollusks, 49, 54.* Monadnock, 221. Monoclinal, 42. Monocotyledons, 63. Moraines, 298.* Mosasaur, 192,* 193.* Mountains, making of, 216, 327. of Paleozoic origin, 145 made after the close of the Paleozoic, 150. made after the Jurassic, 183 made during the Tertiary, 216. See ELEVATIONS. Mount Blanc, 300. Holyoke, 160, 318. Loa, 309.* Tom, 318. Muck, 266. Mud-cones, 316. Mud-cracks, 33 * Muschelkalk, 161. Myriapods, 53, 130. Nautilus, 55 * in the Silurian, 89. Nautilus tribe, number of ex- tinct species of, 253. Neolithic era, 239. New Brunswick coal-area, 115. New Caledonia reefs, 272. New South Wales cliff, 287.* Niagara Falls , rocks of, 28 * 94.* group, 93. River, gorge of, 245. 279. Noeggerathij, See CYCI/>P- T^RIS. North America, form of, 9. geography of. See GEOG- RAPHY. Norwich crag, 206. Notidanus primigenius, 52.* Nototherium, 236. Nova Scotia coal-area, 115. Nummulites, 59.* Nummulitic limestone, 205. Nullipores, 61. Nuts, fossil, 127, 206. Oak, 206. Ocean, depression of, 6, 7. effects of, 286. Oceanic basin, origin of, 331. Ohio, coral-reef of Falls of, 1 J4. Oil, mineral, 122. Old red sandstone, 105. Oneida conglomerate, 93. Onondaga limestone, 103. Oolitic structure, 25. Ooiyte, 161. Orbitolina Texana, 189.* Oreodon gracilis, 215.* Orient, characteristics of, 5. Origin of species, 263. Oriskany period, 93, 95. Orohippus, 212. Orthis biloba, 96.* occidentalis, 88.* testudinaria, 88 * Orthoceras junceum, 88.* last of, 175, 200. Orthoclase, 15. Osmeroides Lewesiensis, 192.* Ostracoids, 54.* of Triassic, 164.* Ostrea sellgeformis, 208.* Otozoum Moodii, 166. Outcrop, 40.* Ox, first of, 216. Oyster, Tertiary, 209.* Palaeaster Niagarensis, 57.* Palaeoniscus lepidurus, 51.* Freieslebeni, 51,* 131.* Paleolithic era, 238. Paleothere, 211 * Paleozoic time, 78. disturbances closing, 150. general observations on, 140. Palephemera mediseva, 165.* Palisades, 160 Palms, first of. 186. Tertiary, 207.* Palpipes priscus, 173 * Paludina Fluviorum, 1^9 * Paradoxides HarlanS 82.* Paris basin, Tertiary animals of, 211. Paumo u Archipelago, 271. Peat, formation of, 265. Peccary, fossil, 214. Pecopteris Stuttgartensis, 163.* Pemphix Sueurii, 173 * Pentamerus galeatus, 98.* oblongus, 96.* Peutremites, 128.* INDEX. 357 Peridotyte, 26, 318. Rhinoceroses, Tertiary, 214.*, Permian period, 115, 123. Quaternary, 234. Petraia corniculum, 88.* Rhizopods, 59.* Petroleum, 122. Cretaceous, 187.* Phacops bufo, 110 * formation of deposits by, Pbascolotherium, 178.* 267. Phenogams, 62. Rhode Island coal-area, 115. Phonolyte, 326. Physiographic Geology, 6. Pictured rocks, 85. ' Rhynchonella cuneata, 96.* ventricosa, 98.* Rill-marks, 33,* 293. Plants, 47, 60. Ripple-marks, 33,* 293. Carboniferous, 123.* Rivers, action of, 275. Cretaceous, 187.* of Paleozoic origin , 146. earliest marine, 76, 81. River terraces, 227,* 230.* Devonian, 99,* 106.* Tertiary, 207.* Roches moutonnees, 299. Rock, definition of, 13 Triassic, 162.* Rocks, constituents of, 14. Platephemera antiqua, 111.* Platyceras angulatum, 96.* Plesiosaurs, 175,* 193. Pleurotomaria lenticularis, formation of sedimentary. 275. fragmental , 20. kinds of, 20. 88.* metamorphic, 21. tabulata, 129.* Pliocene, 202. of Mississippi Valley, sec- tion of, 141 * Pliosaur, 176. origin of Archaean , 75. Podozamites lanceolatus, 163 * origin of Paleozoic, 142. Polycystines, 59* 263. thickness of Paleozoic in Polyps, 58.* North America, 140, 249. Polythalamia. See FORAM.- Rocky Mountains, origin of, NIFERA. 196,217,334. Pompeii, 314. Mountain coal-area, 204. Porphyry, 27, 308. Rotalia, 59.* Portland (England) dirt- bed, 161. Sabal, 206. (Connecticut) freestone, St. Lawrence River in the Qua- 159. ternary, 228. Potsdam sandstone, 80. St. Peter's sandstone, 85. Primordial period, 80. Saliferous group of Britain Prionastraea oblonga, 168.* and Europe. 161. Productus Nebrascensis, 129.* rocks of New York, 94. Protophytes, 61.* Salina rocks, 94, 100. Protozoans, 49, 59 * 187. Salisbury Craigs, 318. Pterichthys, 111.* Salix Meekii, 187.* Pterodactyl, 177,* 193. Salt of coal formation, 122. Pterophyllum, 163.* of Salina, etc, 94. Pteropods, 56.* of Triassic, 161. Pterosaurs, 177,* 193. Sand, 20. Ptilodictya, 88.* Sand-banks, 291, 293. Pudding-stone, 22. Sand-scratches, 274. Pupa vetusta, 129.* Sandstones, 22. Pyrifusus, 191 * Sapphire, 15. Pyroxene, 16. Sassafras Cretaceum, 187.* Sauropus primaevus, 132 * Quadrupeds. See MAMMAL. Scaphites larvscformis, 191.* Quaternary, 201, 219, 237. Schist, schistose rocks, 22. Quartz, 14.* Schoharie grit, 103. Quartz rock, or Quartzyte, 24. Scolithus linearis, 82. Quebec group, 85. Scoria, 27. Quercus, Tertiary, 207.* Scorpions, first of, 130.* Sea-beaches, elevated, 228. Radiates, 49, 57.* Sea-weeds, 60. Rain-prints, 34,* 145. Section of New York rocks, 72 * Raniceps Lyellii, 132.* of the series of rocks, 67.* Rays, 52. Sections of Paleozoic rocks, Reefs, coral, 268.* 105,* 141,* 153.* Regelation, 298 Sedimentarv beds, formation Reindeer era, 231,238. of, 301. Reptiles, 50. Selachians, 52 * Mesozoic, 165,* 174 * 192 * Devonian, 113.* 201. Serolis, 54.* Reptilian age, 158. Serpentine, 18. Shale, 22, 23, 31. Sharks, 52 * Devonian, 113* Teeth ,52,* 173, 210.* Shasta, height of, 307. Sigillaria Hallii, 106. Carboniferous, 125.* Silica, or Quartz, 14. Silicates, 15. Siliceous shells, microscopic, 59,* 61,* 108,* 267. waters of Geysers, 316. Silt, 282. Silurian age, 79. Upper, 93. Siphonia lobata, 189.* Slate, 22, 24. Slaty cleavage, 36,* 329. Sloths, gigantic, of Quater- nary, 236.* Snakes, first of, 210. Soapstone, 18. Solenhofen lithographic lime- stone, 161. Solfataras, 315 Solitaire, 242.* South America, form of, 9. changes of level in, 231 Species, exterminations of. 92, 147, 198, 200, 252, 255. Sphagnous mosses, 265. Sphenopteris Gravenhorstii, 125.* Spicules of Sponges, 59, 108,* Spiders, 53, 130.* Spinax Blainvillii, 52.* Spirifer cameratus, 129.* macropleurus, 98 * mucronatus. 110 * Walcotti, 169.* Spirifers, last of, 174,* 200. Sponges, 59,* 188.* Cretaceous, 188,* 189.* Sponge-spicules, 59, 189. in hornstone, 108.* Spores in coal, 134.* Stalactites, 26. Stalagmite, 26. Star-fishes, 58.* Statuary marble, 26. Steatite, 18. Stigmarise, 126.* Strata, definition of, 27. positions of, 37,* 39 * 44. Stratification, 27,* 31.* Strike, 41.* Strophomena rhomboidalis, 96.* Subcarboniferons period, 113, 119. Submarine eruptions, 314. Subsidence of coast of New Jersey, 232. of Greenland, recent, 232 Subsidences of volcanic re- gions, 314. Subterranean waters, 284. Sweden, Quaternary of, 229. changes of level in, 232. Syenyte, 24, 26. 358 INDEX. Synclinal, 42.* Synclinorium, 335. Syringopora Maclurii, 109.* Talc, 18. Talcose schist, 23. Tapirus Indicus, 211. Teliost fishes 50.* Cretaceous, 191,* 200. Tertiary, 209. Tentaculites, 97.* Terraces on Connecticut River, 227.* of Scotland, 229. origin of, 225, 229. Tertiary age, 206. Tetradecapods, 53.* Tetragonolepis, 173.* Thallogens, 60 Thanet sands, 206. Thecodonts, 133. Thrissops, 51.* Tidal currents, 288. Tiger, 215 Time, length of geological, 245. Time-ratios, 140, 196, 245. Titanothere, 214.* Tourmaline, 17.* Trachyte, 27. Tracks of birds, 167.* Cheirotherium, 174.* of insects, 166.* of reptiles, Carboniferous, 132.* of reptiles, Triassic, 166. Tracks of trilobites, 28.* Transportation by rivers, 281. Trap, 26. of Connecticut Valley , etc. , 160. columnar, 319.* Travertine, 26. Tree-ferns, 125 * Trenton period, 84. Triassic period, 159. Trigonia clavellata, 169 * Trigonocarpus tricuspidatus, 125.* Trilobites, 54 * 81,* 88 * 96* 150. beginning and ending of genera, 147. Tufa, 23, 308 Turrilites catenatus, 191.* Turritella carinata, 208 * Turtles, Cretaceous, 193. Jurassic, 177. Tertiary, 210. Unconformable strata, 43.* Under-clays, 120. Unstratified condition, 29.* Upper Helderberg, 103. Upper Silurian, 93. Ursus spelseus, 233. Utica shale, 86. Valleys, formation of, 277. Veins, 29.* Veins, formation of. 323. Vertebrate-tailed fishes, 51 * 112-* Vertebrates, 49, 50. first of, 98. Vesuvius, 303 Viviparus fluviorum, 169.* Volcanoes, 306. Water, action of, 275. subterranean, 284. freezing and frozen, 294. Water lime group, 94. Waves, action of, 287. Wealden, 161. Wenlock limestone, 95. Whales, first of, 210. Winds, effects of, 273 Wind-drift structure, 32* 274. Woolwich beds, 206. Worms, 53,* 82. Xiphodon gracile, 212. Yoldia limatula, 209.* Yorktown period, 203. Zamia, 62, 162. Zaphrentis bilateralis, 96.* Rafinesquii, 109.* Zeacrinus elegans, 129.* Zeuglodon, 212. THE END. University Press, Cambridge: Electrotyped and Printed by Welch, Bigelow, & Co. VB 24056