FIRST BOOKS OF -.NATURAL HISTORY. ELEMENTS OF GEOLOGY PRP:PARED FOR THE USE OF SCHOOLS AND COLLEGES, ELLIOT, FOURTH STREET. 1845. W. S. W. RUSCHENBFTIGER, M.D. I, LOW OF THE COLLEGE OF PHYSICIANS ; HOS. l| UA MEDICAL SOCIETY; MEMBER OF THE .\L SCIENCES OF iT: L, ETC , ETC. MILNE EDWARDS AND ACHILLE COMTE, PROFESSORS OF NATURAL HISTORY- IN THE COLLEGES OF HENRI IV., AND CHARLEMAGNE. : UNIVERSITY OF CALIFORNIA. FROM THE LIBRARY OF DR. JOSEPH LECONTE, GIFT OF MRS. LECONTE. No. Geology. RXJSCHENBERGER'S SERIES. FIRST BOOKS OF NATURAL HISTORY, ELEMENTS OF GEOLOGY: PREPARED FOR THE USE OP SCHOOLS AND COLLEGES, BY W. S. W. RUSCHENBERGER, M.D. SURGEON IN THE U. S. NAVY ; FELLOW OF THE COLLEGE OF PHYSICIANS OF PHILADELPHIA ; OF THE COLLEGE OF PHYSICIANS AND SURGEONS OF THE UNIVERSITY OF THE STATE OF NEW YORK J HON. MEMBER OF THE PHILADELPHIA MEDICAL SOCIETY J MEMBER OF THE ACADEMY OF NATURAL SCIENCES OF PHILADELPHIA J CORRESPONDING MEMBER OF THE AMERICAN INSTITUTE, ETC. ETC. FROM THE TEXT OF F. S. B E U D A N T, .OYAL ACADEMY OF SCIENCES J INSPECTOR OF STUDIES, ETC. MILNE EDWARDS, AND ACHILLE COMTE, OF THE ROYAL ACADEMY OF SCIENCES J INSPECTOR GENERAL OF STUDIES, ETC. WJCTH THREE HUNDRED E PHILADELPHIA : GRIGG & ELLIOT, NO. 9 NORTH FOURTH STREET. 1846. Entered, according to the Act of Congress, in the year 1843, by W. S. W. RUSCHENBERGER, M.D., in the clerk's office of the District Court of the United States in and for the Eastern District of Pennsylvania. J. Fagan, btereotyper. T. K. & P G^ Collins, Printers. (4) PREFACE THE eighth in the series of " First Books of Natural History," comprises the Elements of Geology. The volume has been compiled chiefly from the work of F. S. Beudant, and that of Milne Edwards, and Achille Cornte. The works of other writers have been consulted, and freely used ; amongst them, Ansted, Lyell, Mantel, Murchison, Trimmer, Buck- land, Bakewell, De la Beche, Lea, Parkinson, Phillips, Dana, Percival, Charles T. Jackson, Henry D. Rogers, Morton, Conrad, &c., &c. The numerous illustrations, to the execution of which we par- ticularly invite attention, were engraved by MR. G. THOMAS, of Philadelphia. We believe better wood-cuts have never been engraved in the United States for any work of the kind, and as a sample of the art, they are creditable to our country. The explanations and etymologies of technical words are given as they occur, either in the text, or in foot-notes ; and in many, if not in all cases, the pronunciation of these words has been indi- cated by accents. An ample glossary, which will be found suffi- ciently copious for the general reader, is also appended. When it occurs, the Greek omega has been marked thus (d), and italics have been substituted for Greek characters, because, it is presumed, many who may use this volume are unacquainted with the dead languages. It is believed this small volume contains all that is requisite for acquiring a knowledge of the Elements of Geology, except the desire and consequent labour of the student, essential elements in the acquisition of knowledge of every kind. Without labour, knowledge cannot be obtained ; to reach the goal, the road must be travelled, no matter how smooth and easy it may be made ; there 11 101308 (5) VI PREFACE. is no royal path to learning. When the student is master of the information contained in this book, he will be fully prepared for reading, advantageously, voluminous treatises, and the various geological reports and papers almost daily issuing from the press. All knowledge is necessarily communicated from one person to another, through the medium of words, or signs. When branches, or parts of knowledge, or ideas, become familiar and common, the words representing them cease to be difficult. Then the complaint about " hard words" ceases. Few persons acquainted with the instruments, complain that the words Thermometer, or Barometer, are " hard ;" the first is familiar to all, even to those ignorant of its construction and numerous practical uses. The names Quadrant and Sextant are not " hard words" to the most unlettered seaman, and we may remark, in passing, that the science of navigation would not be rendered of more easy acquisition, if those instru- ments were designated by the more familiar names of Bob and Bill. The votary of music does not find the numerous terms, such as clef, minim, semibreve, crotchet, or sonata, overture, aria, or pianissimo, crescendo-, forte, &c., obstacles in acquiring a know- ledge of the science. The same is true of all human sciences. Each has its technicalities and significant names, which cannot be changed without injury, or taken away without increasing the difficulties of acquiring knowledge. The names and terms employed in Natural History are very numerous, but most of them are very significant and appropriate. [t is true, some are of doubtful or remote meaning, and might have been better. The fashion of naming natural objects after dis- tinguished individuals, might be safely abandoned. All who are so fortunate as to discover a new genus, or species, should carefully select a name for it significant of some prominent quality or attri- bute, so that the generic and specific names would be together descriptive, as far as possible, of the object. Hard names are no real obstacles to the acquisition of science, and no benefit would arise by departing from systematic nomencla- ture in elementary works. One great object of such works, is to explain the meaning of the names and terms employed. Nursery, or "baby talk," does not facilitate a child in learning to speak, or in acquiring ideas ; nor would the study of geology be facilitated PREFACE. Vll by analogous language. Probably Natural History has been made less interesting in our country, and has been less beneficially studied, in consequence of attempts to employ old words, already appropriated to well-known things, to designate new objects. The writer trusts the above remarks will be sufficient to meet the objections of all those who cavil about " hard words." Besides being in itself very interesting, forming as it were the blossom and bloom of Natural History, a knowledge of zo'ology and botany being necessary to the study and recognition of animals and plants in the fossil state, Geology is practically useful in a high degree. To agriculture, and many of the mechanic arts, it is of great advantage, and it is not totally useless to any avocation or pursuit. A competent knowledge of Geology better enables the architect to select materials for buildings, as well as sites for their erection ; the engineer learns from it where he may run a railroad or canal with the greatest facility, and least cost; the miner is guided in the pursuit of mineral wealth, metals, or coal, with greater certainty of success when assisted by this noble science, which is more unerring than witch-hazel or diving rod ; it facili- tates the physician in the study of climate, and opens a wide field to the divine for pointing out the wonders of the creation, and the goodness of God. Before its natural history was explored, at a cost of more than two hundred thousand dollars, voted by the Legislature, vast sums of money were spent in vainly hunting for coal-mines in the state of New York. But after the geological surveyors reported that no coal could ever be discovered in the districts they had examined (because the several formations constituting the surface of these districts were those which are naturally below the coal-bearing series), these wasteful speculations were abandoned, although per- sons unacquainted with Geology complained that, "not satisfied with their inability to find coal themselves, the surveyors had decided that no one else would ever be able to detect any, having had the presumption to pass sentence of future sterility on the whole land," But time will show there was no presumption or guess, but the sentence of the geologists was a positive deduction from their science a deduction that has saved thousands of dollars to individuals, who would still seek for coal where it does not exist, were it not for a knowledge of Geology. Vlll PREFACE. In order to study Geology with greater facility and success, schools should be supplied with drawings, representing the principal facts in the science. Also, with some living shells, marine, flu- viatile, and terrestrial ; specimens of coral, turf, and volcanic pro- ducts, all distinctly labelled ; these, after being pointed out, should be left accessible to the pupils. To teach them the composition of the crust of the earth, there should be drawings of the different stratifications, and collections of fossils characteristic of the several formations, all distinctly labelled. Where fossils cannot be obtained, casts representing them will serve a good purpose. Specimens of the various crys- talline and sedimentary rocks should form a part of the teacher's apparatus. To illustrate the various effects attributable to igneous and aqueous causes, there should be some well-selected specimens, distinctly labelled, of fossil-shells, encri'nites, of echini'deae, of madrepores, &c., in order to compare them with those now existing. Drawings on a large scale, of faults and crevices, of dykes and injected rocks, of basaltic bosses and of erosions attributable to water, should also belong to the school. During and after the lesson referring to a particular part of the subject, these speci- mens and drawings should be exhibited and explained to the pupils. U. S. Naval Hospital, ? New York, October 16th, 1845.3 CONTENTS. LESSON I. GEOLOGY DEFINED. Form of the Earth. Its Surface. Internal heat. Mineralogy denned. Definition of the terra Rock. Formations. Strata. The origin of Strata. Vegetable Earth. Alluvium. Divi- sion of the Formations. Plutonic formations. Neptunian or Strati- fied Rocks. Order of Strata. Temple of Jupiter Serapis. Subsidence and elevation of coasts p. 11 to 20. LESSON II. ORGANIC REMAINS. Fossils how produced. FIRST GEOLOGICAL EPOCH. Primitive Rocks. Granite. Gneiss. Mica- Schist. Argillaceous Schist SECOND GEOLOGICAL EPOCH. Transition Formation. Cambrian System. Silurian System. Trilobites and other Animal Remains. Devonian System. Fossil Fishes. Fossils. Limits of the Transition Formation. Strata changed in position by Geological Convulsions p. 21 to 36. LESSON III. THIRD GEOLOGICAL EPOCH. Secondary Formation. Carboniferous Forma- tion. Old Red Sandstone. Fossils. Coal Formation. Fossils. Extent of Coal Measures. FOURTH GEOLOGICAL EPOCH. New Red Sandstone. Fossils. Triassic System. Bunter Sandstein. Muschelkalk. Keuper. Ammonites. Fossils. FIFTH GEOLOGICAL EPOCH. Lias or Liassic System. Fossils. Ichthyo- saurus. Pleisiosaurus. Pteroda'ctylus. Oolitic System. Fossils p. 36 to 66. LESSON IV. SECONDARY FORMATION continued. SIXTH GEOLOGICAL EPOCH. Cretaceous Formation. Lower Cretaceous Sys- tem. Fossils. Wealden Deposit. Greensand. Gault. Fossils. Upper Cretaceous System. Fossils. Extent of Cretaceous Formation. Table of Formations p. 66 to 77. LESSON V. SEVENTH GEOLOGICAL EPOCH. Tertiary Formation. Eocene Beds. Paris Basin. Fossils. Anoplotherium. Paleotherium. Miocene Beds. Dinotherium Lignites. Pliocene Beds Fossils Bone caverns. SUPERFICIAL DEPOSITS. Drift. Diluvium. Megatherium. Boulder For- mation. Alluvium. Big Bone Lick. EIGHTH GEOLOGICAL EPOCH. Modern Formation p. 77 to 96. LESSON VI. INFLUENCE OF INTERNAL AGENTS ON THE SURFACE OF THE EARTH. EARTHQUAKES. Description of. Effects of. Changes of level produced by. Upheaval and Subsidence. Constant level of Seas. Slow and Progressive Subsidence. General Conclusion. X GEOLOGY. CONTENTS. VOLCANIC PHENOMENA. Explosion. Eruption. Island of Saint George.- Monte-Nuovo. Jorullo. Vesuvius. Definition of a Volcano. Sub- marine Eruptions. Volcan of Unalaska. Crater of Elevation. For- mation ef Craters. Effects of Upheaval. Form of Volcanic Islands. Periods in the Formation of a Volcano. Interior of Craters. Kirauea. Solfataras. Volcanic Ashes. Lava Currents. Characters of Lavas. Dykes. Gaseous Volcanic Products. Eruption of Mud. Solid Pro- ducts of Volcanoes. Trachyte. Obsidian. Compact Lavas. Porous Lavas p. 96 to 122. LESSON VII. INFLUENCE OF EXTERNAL AGENTS ON THE SURFACE OF THE EARTH. Effects of the Atmosphere. Degradation. Effects of Winds. Dunes. Ef- fects of Lightning. EFFECTS OF WATER. Dissolving Power. Softening Power. Denudation. Erosion. Effects of weight of Water. Running Waters. Debacle of Lakes. Mud-Torrents. Slope of Torrents and Rivers. Rolled Flints. Transportation by Ice and Glaciers. Action of Waves. De- posits formed by Water. Geysers. Structure of Sedimentary Deposits. Talus. Effects of Transport or Drift. Effects of Oscillation in Waters. Nature of Deposits from Water. Coral Reefs. Polyparia. Peat-Bogs p. 122 to 144. LESSON VIII. EXPLANATION OF VARIOUS PHENOMENA. Consequences of Central Heat. First effect of Cooling. Warm-Springs. Deposits referable to Sedi- ment. Fresh Water Deposits. Fossils of. Marine Deposits. Fossils of. Carbonaceous Deposits. EFFECTS ATTRIBUTABLE TO UPHEAVAL AND SUBSIDENCE. Shell Deposits and Raised Beaches. Submarine Forests. Tracks of Quadrupeds and Birds. Dislocation of Strata. Faults. Crateriform arrangement of Strata. Valleys of Elevation. Upheaval without Dislocation. Dis- tortion of Strata. Origin of Valleys. Valleys from Dislocation from Subsidence from Folding or Plaiting from Erosion or Denudation. Origin of Caverns p. 144 to 166. LESSON IX. EXPLANATION OF VARIOUS PHENOMENA CONTINUED. Deposits attributable to Volcanic Action. Lava. Basalt. Action of Basalt on Adjacent Rocks. Dolomisation. Giants' Causeway. Trachytic Formation. Trap Rocks. Porphyry. Granitic Rocks. Injection of Granite. Metalliferous Veins.--Metamorphism.--Effects of Erosion--p. 166 to 181. LESSON X. CLASSIFICATION OF FORMATIONS. Different kinds of Stratification. Dip. Strike. Conformable Stratification. Unconformable Stratification. False Stratification. The form and habits of an Animal deducible from a single bone. Relative ages of the principal catastrophes of the Globe. Systems of Upheaval. Classification of. State of Europe at different epochs of Formation. Deluge Geogeny p. 181 to 210. GLOSSARY p. 211 to 235. OF THE UNIVERSITY ELEMENftlJF GEOLOGY. LESSON I. GEOLOGY DEFINED. Form of the Earth its Surface Internal Heat Mineralogy defined Definition of the term Rock Formations Strata The Origin of Strata Vegetable Earth Mluvium Division of the Formations Plutonic Forma- tions Neptunian or stratified Rocks Order of Strata Tem- ple of Jupiter Serapis Subsidence and Elevation of Coasts. 1. GEO'LOGY (from the Greek, ge, the earth, and logos, dis- course), or science of the earth, is that branch of Natural History which treats of the physical constitution of our globe. 2. The earth, as is generally known, is in form of a ball, or spheroid, slightly flattened at the poles, floating freely in space. Its diameter is about 8000 miles, and its surface is irregular; here it is studded with long chains of mountains, there hollowed by deep depressions ; but these inequalities, however gigantic they may appear, when compared with objects surrounding us, are in reality very trifling, in comparison with the mass of the globe ; they are proportionally much less than those we see on the skin of the smoothest orange, and if represented on a ball three feet in diameter, the highest mountains would be still so small as almost to require a microscope to perceive them. 3. The deepest excavations of the surface of the globe are covered by great masses of water which conceal them and prevent their examination ; but there is reason to believe that the most pro- found depressions do not much exceed three miles in depth, below the surface of the sea, and we know by exact measurement that the summit of the loftiest mountains is not six miles above the same level. Mont Blanc, the highest mountain in Europe, is 15,748 feet; Mont Perdu, of the Pyrenees, is 11,168 feet; Peak of Teneriffe, 12,172 feet; in South America, in the Cordillera of the Andes, there are still higher mountains ; 1. What is Geology ? 2. What is the form of the earth ? What is its size? What is the cha- racter of its surface ? 3. What is the greatest depth of the sea ? What is the greatest height of land above the level of the sea ? (11) 12 INTERNAL HEAT OF THE EARTH. Chimborazo, 21,440 ; Illimani, 24,450 feet ; and Scrota, 25,000. The high- est mountain in the world is in Asia, the Himalaya, which rises 26,862 feet above the level of the sea. 4. The surface of the earth has not always possessed the same configuration that it now presents ; it has been frequently upturned, and there is even reason to believe that the entire globe was a liquid mass, melted by heat, and that it gradually became solid as it cooled. 5. Except at comparatively shallow depths, we cannot examine the nature of the materials constituting our globe, not even by descending into mines, excavated for the purpose of extracting the wealth they contain ; for the deepest of these excavations do not exceed 500 yards. But by calculations, it has been inferred that the centre of the earth cannot be occupied, either by water, or by vapour, but by matter as heavy as our heaviest metals, and so hot that it is probably in a state of constant fusion. 6. A great number of facts concur in proving that the earth possesses an internal heat (the remnant of its original heat), inde- pendent of that which it receives from the sun. Its temperature increases in proportion as we descend to considerable depths ; there are some very deep mines in which the workmen can only labour when naked, and wherever the water of a spring rises from a great depth, its temperature is always very high. This increase of temperature has even been measured, and it has been ascer- tained that the heat of the earth increases about two degrees, Faren- heit, for every 70 to 100 feet. In very deep cellars, where the influence of the seasons is not felt, and where the temperature is always the same, the thermometer, at Paris, stands at about 51 degrees, and at a depth of 200 feet below these cellars the heat is about 55 degrees ; at a league below the surface, the temperature must be above that of boiling water, and at a depth of less than two leagues, it must be sufficient to melt tin. 7. It appears to be demonstrated, that the globe, at some remote period, was in a state of incandescence, or liquefaction from heat, and that it cooled by degrees ; but we must not conclude that this cooling process has continued to the present time, and is still going forward ; it has almost, if not entirely, ceased. From the earliest records of history, to the present moment, the temperature of the 4. Has the surface of the earth always been the same in form and shape as it now is ? Is it supposed that the globe has always been in its present condition ? 5. What occupies the centre of the earth ? 6. Is the temperature of the earth the same at its centre as it is on the surface ? What reasons lead us to the conclusion that the earth possesses an internal heat? 7. Is it supposed that the earth is becoming cooler and cooler every day ? How is the earth enabled to preserve its temperature ? STRATIFICATION. 13 globe has not sensibly changed, and by the calculations of the learned, it is proved that the surface of the earth receives from the sun during a year a quantity of heat equivalent to that which it loses in the same space of time ; the internal heat of the earth no longer influences the temperature of its surface, except in an in- sensible degree, and to diminish this influence, which is almost none at all, one-half, would require the lapse of 30,000 years. 8. Our knowledge of the central portion of the globe is limited to what we have just said of its weight and temperature ; but the solid crust, constituting its surface, has been better studied. 9. This crust is not formed of a single piece, but is composed of a great number of various materials. The study of these vari- ous substances, particularly, belongs to Mineralogy ; the study of their mutual relations and the more or less important part they play in the constitution of the globe, is the province of Geology. 10. In general we give the name of rocks to mineral substances, which are united in great masses, and apply the term formations, to diverse assemblages of rocks which appear to have been formed under the same circumstances. The word rock, as used by geologists, is applicable to all mineral masses, whether hard or soft, and therefore includes in its meaning, sand, marble, clay, granite, 19), (from the Latin, catena, a chain, and porus, a pore). The oval form of the cells when united laterally, and the flexu- ous disposition of the lamellae, give rise .in transverse sections to elegant catenated mark- ings, from which ap- pearance the fossil has received the name of chain-coral. The spe- cies figured (Jig. 19), is common in Silurian limestone, and some- times forms hemispher- ical masses more than a foot in diameter. 36. The organic re- mains of the Cambrian system differ from those of the Silurian system in being less developed ; the genera and species of mollusks and corals found in both are alike. 37. The DEVONIAN SYSTEM (so called be- cause it is largely deve- Fig. 20.* Fossil Fishes of the Devonian System, loped in Devonshire, England) forms the su- perior part of the preceding formation. It appears to be composed * Explanation of Fig.2Q. 1. Pterichthys cornutus, seen from above (Pterichthys, from the Greek, pteron, wing, and ichthos, fish : cornutus, La- tin, horned. The horned wing fish). 2. Coccosteus oblongus. These figures are restored with great accuracy from the best preserved specimens hitherto discovered. The British species of fossil wing-fishes, of which five or six are known, are all very small, varying in length from one to eight or ten inches. But in the Devonian strata of Russia enormous spe- cies occur ; the spines of some of them exceed a foot in length. See Man- tell 1 s Medals of Creation. London, 1844. 36. How do the fossils found in the Cambrian rocks differ from those of the Silurian System ? DEVONIAN SYSTEM. 33 at first of pudding-stone, with which it commences, and to pass to sandstone, with which it alternates at different places. Then come Fig. 21. Caryopliy'llia fastigia'ta. Fig. 23. Calceola sandalina. Fig. 22,Amplexus coralloi'des sandstone-schists, more or less fine, different species of schist, lime- stones, alternating with each other, in the midst of which are found beds of anthracite. These va- rious materials are differently developed in different coun- tries : in England the sand- stones predominate. They form the old red sandstone, comprising strata of clay and marl of different colours. In other places the limestones prevail with different clay- slates, or chloritic schists, some- times intercalated with schistose Fi S' M'Clyme'ma linea'ris. quartz, as in Devonshire, and sometimes almost alone, as in Corn- wall. 37. What is the origin of the term Devonian System ? What is its geological position ? Of what rocks does it consist ? 34 SLATE SYSTEMS OF ROCKS. 38. This system presents us with depots of the oldest com- bustible materials known ; and we find in it ferns, ca'lamites, divers species of plants, differing but little from the plants found in the coal formation which immediately follows. We here find also a great many pol'yps more or less analogous to the Caryophyllia (fig. 21) ; Jimplexus (fig. 22), by some re- garded as polyps and by others as chamber- ed shells, which are found nowhere beside. Fig. 25. Megalodon cuculla'lus. - ~, ,. * so nearly resembling certain productus, appears to be characteristic of the Devonian rocks ; and perhaps also the Clymenia Hnearis (Jig. 24), a cham- bered shell with aventral siphon. Certain peculiar bivalves are also found (Jig. 25); some brachiopods, and among others the Terr ebra' tula porrecta (Jig. 26). 39. Slates, so" extensively used for roofs, are furnished from this group of ancient rocks ; and on many we find im- pressions of trilobites. The upper part of the transition strata often contains car- boniferous materials, some- times disseminated among the schists, and at others constituting more or less ex- tensive masses, w r hich are generally composed of anthracite, though sometimes of bituminous coal. 40. These three systems of rocks, namely the Cambrian, Silu- rian and Devonian, which are not easily distinguished from each other, are found in most countries of Europe, where their assemblage constitutes the greater part of what is named the transition or palaeozoic formation. They abound in Brittany : there the anthraciti'ferous mass forms a stripe along the Loire, ex- tending from Maine to Morbihan, as well as other depots in Sarthe and Mayenne. These rocks are found through the whole chain Fig. 26. Terrebra'tula porrecta. 38. What fossils are found in the Devonian System ? 39. What useful material is found in the Devonian System ? 40. What systems of rocks constitute the palaeozoic formation ? is this formation met with ? Where POSITIONS OF THE DIFFERENT STRATA. 35 of the Pyrenees, in the southern part of Cevennes, in the moun- tains of Forez and Beaujolais, and in some parts of Vosges. They form all the Hundsruck, Eiffel, and Ardennes and the southern part of Belgium. They are met with in Hartz, in Saxony, and different parts of Germany, Sweden, and Norway ; and they abound in England as well as in the United States. They every- where offer a matrix for anthracite. 41. Geologists are not agreed as to the natural limit between these strata and those of a more recent order, generally designated under the name of secondary formation ; but most authors con- sider the period of transition to cease beneath the carboniferous rocks and the coal measures. 42. While the different stratified rocks we have spoken of were in progress of formation, there were effusions of granite and other igneous rocks on their surface, and these geological convulsions have produced in the strata elevations and changes of direction, so that many of them are raised up and are very much inclined and in some instances almost vertical. It was during one of these revolutions that the mountains of Westmoreland and Cornwall, in England, were suddenly elevated ; a part of those of Brittany, and Bigorre, &c., in France, of the Hundsruck, Eiffel, and Hartz, in Germany, and many other mountain chains. The superior transi- tion strata, which were formed subsequently to this convulsion and rested on the edge of strata thus upheaved, were in turn dislocated and raised up, and according to the observations of a French geo- logist, Elie de Beaumont, this elevation appears to have been ante- rior to the formation of more recent rocks than those we have yet mentioned, and to correspond with the eruption of masses of igne- ous rocks of the mountains of Vosges, known under the name of buttons of Alsace and Comte. The elevation of the hills of Bocage, in Calvados and several mountain chains in England, Germany and Poland appears to have occurred about the same time. The following diagram (fig. 27), represents the several strata we have described, in a horizontal position, one lying above the other, and embraces the granite or plutonic rocks below, next the aqueous or metamorphic rocks, and above the whole, the transition formation, consisting of the Cambrian, Silurian and Devonian Sys- tems of strata. {Devonian Sys'em Fossils- -Fishes. Silurian System Fossils ' Frilohi'es rv_ 07 -Polyps. Tig* <*/ {Arzillaceous-chist. Mica-schist. Gneiss. Granite Pluionic Rocks. A B 41. How is the transition separated from the secondary formation? 42. What is supposed to have happened while the stratified rocks were being formed ? 36 THIRD GEOLOGICAL EPOCH. If we suppose the strata to have been in this position at the time of a geological convulsion, such as we have alluded to above, and that the granite should force its way upwards at A or B, we should find perhaps all the relations of the strata changed, presenting something like the arrangement represented in the following figure. Transition. Stratified. Fig. 28. The above figure represents the effect of the sudden rising up of a mass of granite, bursting and breaking through all the strata that were lying above it. Instead of a horizontal level surface, as in fig. 27, we have a mountain of granite, from the lowest stratum, overtopping all the more recent formations ; and the ends of the several strata, where they were broken to give passage to the granite, are brought up towards the earth's surface, represented by the dotted line. In such a case as we here suppose, it would be very difficult for one who had not studied the subject to determine which stratum was first formed : it might seem to him that inas- much as he finds the granite occupying the highest point, and the transition rocks the lowest, that the granite is of the last or most modern formation. LESSON III. THIRD GEOLOGICAL EPOCH. Secondary Formation Carbonife- rous Formation Old Red Stone fossils Coal Formation Fossils Extent of Coal Measures. FOURTH GEOLOGICAL EPOCH. New Red Sandstone Fossils Triassic System Bunter Sandstein Mushelkalk Keu'per Ammonites Fossils. FIFTH GEOLOGICAL EpocH.~-Zz's, or Lia'ssic System Fossils I'chthyosau'rus Plei'siosau'rus Pteroda' ctylus O'olitic System Fossils. THIRD GEOLOGICAL EPOCH. Secondary Formation Carboniferous Formation. 1. After the great revolutions which seem to have terminated the ancient period commonly designated as the transition epoch, OLD RED SANDSTONE, &c. 87 the earth appears to have remained in a state of repose for a long time, which permitted new generations of organized beings to mul- tiply on its surface, and mineral substances, carried by the waters, to be deposited in great layers, and to entomb in their substance the solid remains of the exuviae of contemporaneous animals and plants. 2. The first deposits which took place during this geological epoch, constituted the strata of sandstone, conglomerate, (an assem- blage of fragments of rocks and pebbles, cemented together by other mineral matter,) clay, calcareous rocks, &c., and from their union resulted the formation called by geologists the old red sand- stone, on account of its antiquity and prevailing colour. But this state of things was soon changed, and there was formed, slowly and gradually, at the bottom of the waters, an immense stratum of calcareous rocks, seven or eight hundred feet in thickness ; then the sandy sediment alternated with these limestones, and above this great formation, designated under the name of carboniferous (coal- bearing) limestone, numerous strata of sandstone, schistose cky and coal were accumulated. 3. The fossils of the old red stone are somewhat numerous, and belong, for the most part, to marine animals, among which was a fish of strange form, called cephalaspis, (from the Greek, kephale, head, and aspis, shield or buckler,) because its head resembles a kind of buckler (Jig. 29). Fig. 29. Cephalaspis Lyellii. The remains of the genus Cephalaspis (fig. 29) are found chiefly in the upper beds of the old red sandstone of Scotland, but also in Herefordshire and Wales. " In this genus, the head is very large in proportion to the body, and occupies nearly one-third of the entire length of the animal ; its outline is rounded and crescent-shaped, and the lateral horns slightly incline towards each other, their points being nearer to one another than they are to the round part of the snout. The middle of the head is elevated, and the sides dilated, so as to overlap the body, and extend considerably behind it; but perhaps the head only appears to extend so far, owing to accidents of displacement since the death of the animal. The eyes are placed in the middle of the shield, near to each other, and are directed straight upwards. It is imagined that the pointed horns of the crescent may have been useful 1. What happened after the termination of the transition period of geo- logical history ? 2. What were the first deposits after the transition period ? 3. What is the character of the fossils of the old red sandstone ? What is the Cephalaspis ? 4 CARBONIFEROUS LIMESTONE. as defences when the fish was attacked by the powerful cephalopoda which inhabited the ocean at the period of its existence." The head and body are covered with scales, of peculiar and varied shapes. Ansted. 4. The carboniferous limestone, also called mountain limestone, and metalliferous limestone, affords several varieties of black, bluish grey, and variegated marbles, as well as ores of lead, cop- per, zinc, &c. It contains a great number of organic remains, such as divers polyparia cyathophylla (Jig. 18), madrepora, &c., encrinites, which belong to the division of crinoidea (fig. 30). It also contains the remains of a number of mollusks, as the orthoceras lateralis (fig. 31) ; goniatites (fig. 32), which resem- ble the nautilus ; bellerophons (fig. 33), which, with analogous forms, are not chambered ; euomphalus (fig. 34) ; spirifers and productus in great variety, especially (figs. 35, 36). The Crinoidece, (from the Greek, krinon, a lily, and eidos, resemblance,) a family belonging to the class of radiate animals, are remarkable for the simplicity of their organization, and the peculiarly com. plicated structure of their skeleton. The animal resem- bled a true polyp or coral animalcule ; the body consisted of a gelatinous tube, contracted at one extremity, by which it was attached, and furnished at the opposite end with a variable number of delicate contractile filaments placed around the opening which represents the mouth. The calcareous skeleton was formed within the tube, and consisted of thousands of regularly-shaped pieces, kept together by the tough membrane which enclosed them during the life of the animal. The family is divided into genera, according to the form of the stems, or according to its general shape. When the arms or stems are round, it is an Encrinite ; Fig- 30 ^-Cyatho- t ' ie cyathocrinites (Jig. 30) takes its name from the criniles planus. Greek i kuathos, a cup, and krinon, lily. Many limestones are composed almost exclusively of the remains of species of Crinoidea, as at Lockport, New York ; and various genera of this family are found in Alabama, near Huntsville. The Orthoceras^ or orthoccratite, (from the Greek, orthos, straight, and keras, horn,) is straight, or slightly bent, cylin- drical, slightly conical, many-chambered cell ; the chambers are separated by plain septa, which are concave towards the larger end, and pierced with a siphuncle. Go'nialites (Jig. 32), (from the Greek, gdnia, an angle,) is a genus of extinct cephalopods, which inhabited a cham- bered shell resembling that of the am- monites. Belle'rophon (Jig. 33), (from the Greek, Bellerophontes, the name of a fabulous hero,) a genus of cephalopods which in- . Ortho- habited chambered shells similar to those ceras lateralis. of the argonaut and nautilus. Fig. 32.Go'nia. tiles cvolutus. 4. What are the characters of the carboniferous limestone ? COAL FORMATION. The Euomphalus (fig. 34), (from the Greek, U, properly, and omphalos the navel,) was a gasteropod mollusk. The shell is often exceedingly thick, and is divided irregularly into a number of compartments or chambers, provided with a solid tube running through them, entirely shutting off that part of the shell in which the animal dwelt, from the smaller and uninhabited portion. These empty spaces served, no doubt, as floats, rendering the whole mass of the shell and animal sufficiently light to move easily in the water. Ansled. Fig. 33.Belle'ro- phon coslatus. Fig. 34. Euom'pkalus penta'ngula'tus. Fig. 35. Spi'rifer glaber. Fig. 36. Productus Martini. 5. At the period of the Coal Formation, the earth appears to have been occupied, in a great part, by a deep sea studded with islands, covered by an abundant and luxuriant vegetation. The then existing plants differed very much from those now living ; hundreds of different species are known, but almost the whole of them belonged to the class of vascular cryptoo-a'mia : they are principally ferns, equisita'ceae, lycopodia'cere, that is, plants of a very simple structure but of gigantic size. The tree-ferns, of which existing species do not exceed 20 or 25 feet in height, even in the torrid zone, and generally not more than 8 or 10 feet, then grew, in localities far beyond the tropics, from 40 to 50 feet high ; and other plants, whose representatives of the present time are mere herbs, then rose to 60 feet in height. 6. In that period, there were also insects resembling weevils and neuro'ptera of the present day ; scorpions, which differed from the 5. What was the condition of the earth at the period of the coal formation ? 40 COAL FORMATION. existing species in the number of their eyes ; fresh-water mollusks, and very remarkable fishes, which, in certain respects, resembled reptiles, and had their bodies covered by thick solid plates. 7. The debris of the plants of that period, accumulated in im- mense masses and altered by time and other causes, were trans- formed into the combustible material, which is so immensely valuable, known under the name of coal. 8. The deposits of coal begin, in France, ordinarily with pud- ding-stones formed of the debris of different rocks from the sur- rounding country, often comprising gigantic blocks scarcely rounded. Sometimes finer pudding-stones alternate with sandstone, which always constitutes a chief part of the deposit. Very numerous va- rieties of these sandstones, arising from the size of the grains of quartz and the quantity of argilla'ceous matter entering into their composition, are found ; they are frequently micaceous and schistose ; they contain beds of clay -slate and bituminous schist, which are sometimes very thick, but rarely calcareous strata. The masses of coal are scattered throughout, but are always separated from the sandstone by beds of slate ; these are at first nearly pure, then mixed with the combustible, and finally are represented alone above the deposit. 9. Besides the coal formed by the accumulation of the debris of decomposed plants, the coal-measures con- tain a great number of the remains of plants which retain their organic charac- ters : the stems and trunks of trees are found in the sandstone ; the leaves have left their imprints perfectly preserved in the schists and clays which accompany the coal. 10. The impressions of ferns are ex- tremely numerous ; among them is the Pecopteris (fig* 37), of which the leaflets, but little detached from the pedicle, are joined in a single leaf, deeply incised, in which we recognise a principal nervure, from which the secondary nervures arise perpendicularly ; the Sphfcnopteris (Jig. 38), analogous to the preceding, but in which the leaflets are more distinct, deeply lobed, and have the nervures radiate al- most from the base ; the Neuro'pteris Fig.31. -Pecopteris aquilina.^g which a ls has the leaflets de- 6. What animals existed at that period ? 7. From what was coal formed ? 8. In what kind of rock is coal found ? 9. In what do we find impressions of plants ? COAL FORMATION. 41 tached, but entire and rounded, and the nervures arise very obliquely from the middle nervure, and afterwards frequently divide ; and a great number of other genera founded on the form of their leaflets Fig. 3d. Sp/tanopleris Haninghausi. Fig. 39. Neuropteris Loshii. and the arrangement of their nervures. We also find various other plants, the families of which are uncertain, such as the Spheno- phyllites (fig. 40), Jlnnula'ria, &c. (fig. 41), which are very abundant in certain localities. Fig. 40. Spheno'pJiyllum dentatum. Fig. 41. Annula'ria brevifolia. 11. True equisita appear to have existed in the coal-measures ; but we are also led to place in the same family certain stems, grooved lengthwise, with joints at intervals from which branches sometimes spring (Jigs. 42, 43). These stems, called ca'lamites, 10. Name some of the genera of fossil plants found in coal-beds. 4* 42 COAL FORMATION. are often found, like all the rest of those of which we speak, con- verted into argillaceous matter, which has become hard, or into car- bonates of iron, but rarely into silicious matter. The external vegetable tissue is frequently found to have passed into a carbonous state. Fig, 42._ Calami'tes suckovii. Fig. 43. Calami'tes cann&fo'rmis. 12. The Lycopodia'cex embrace various species of Lepidode'n- drons (figs. 44, 45), of which entire trees have been sometimes found, upwards of sixty feet in height. Their trunks present rhomboidal projections, spirally arranged, which clearly exhibit near the top cica'trices of leaves. Fig. U.Lepidode'ndron crena'tum. Fig. te.Lepidode'ndron e'legans. 13. The Sigilla'nse (fig. 46) seem to range themselves next to the Cyca'decD ; their stems, flattened by pressure, are channelled lenothwise but not articulated, and the cica'trices are arranged in a longitudinal series. The stems, called stigma'ria (Jig. 47), are, ~~11. What genera belonging to the family of equisita'cere are found in coal-beds ? 12. What fossil plants of the family of lycopodia'cesB are found m coal- measures ? COAL FORMATION. 43 according to Ad. Brongniart, probably only the roots of plants, the body of which is traversed by a ligneous axis surrounded by soft fleshy parts. Fig. 46.Sigilla'ria pachyde'rma. Fig. 47. Stigma'ria Jicoi'des. 14. The co'nifers, which, from the consistence of their wood, seem to have participated largely in the formation of carbonaceous matter in different strata, present us, in the different coal- measures, especially in the upper beds, species approxima- ting to the arauca'ria in their spirally-ar- ranged sessile leaves. M. Ad. Brongniart refers the whole of them to the genus Walchia of M. Stern- berg, of which two species, with their leaves and fruit, are here figured, (Jig. 15. Animal re- Fig. 48. -a Walchia Schlatheimii. b Walchia Hypnoidcs. mains are not very common in coal-mea- sures ; stih 1 some are found, and even in great numbers in certain 13. What are sigillariae ? What are stigmarise ? 14. What genus of conifers is found fossilized ? 44 COAL FORMATION. localities. From the calcareous beds, subordinate to these sand- stones, in the environs of Edinburgh, Dr. Hibbert has collected the remains of enormous sauroid fishes, the strong and longitudinally striated teeth of which, as well as the whole osseous system, remind Fig. 49. Lower Jaw of the Holopticus Hibberti. us of the largest sized reptiles. Fig. 49 represents, very much reduced, a portion of the lower jaw of one of these voracious crea- tures, and fig. 50 a tooth of the natural size of another species. The limestone in which they are found also contains particular concretions (fig. 51) which are considered to be the excrement of these animals, and, on this account, called coprolites, (from the Greek, kopros, dung, and lithos, stone). The family of squalae was then represented by the division of cestra' dons, characterized by teeth adapted for grinding, (yz^.52); and by that of the hybodons, with conoidal but not tren- chant teeth, the ena- mel of which is plaited on both surfaces (Jig. 53). The true sharks, Fig. 50. Tooth of the w i t h teet h flattened Megalichthys Hibberti. and trenchar>t on tne edges, (Jig. 54), did not then exist, and did not appear until very much later in the creta'ceous formation. 16. Other fishes are found in the coal-basins of the continent of Europe, either in the bituminous schists, as at Sarrebruck and at Antun, or in kidney-shaped masses of carbonate of iron, as at Saint-Etienne. They belong to neighboring genera of sturgeons, named by M. Agassiz palxoni'scus, (Jig. 56), and am'blipterus, and seem to have lived in fresh water. 15. What animal remains are found in the coal-measures ? What are coprolites ? 16. Are any other fishes found in coal-beds ? Fig. 51. Coprolilf-s. COAL FORMATION. 45 17. Marine shells are rare in coal strata, and are only found in the subordinate limestone of Belgium and England ; but at the same time there were some species of unio and some small ento- mostracans Avhich indicate at least an afflux of fresh water to the sea at the points where these particular deposits were made. Fig. 52. Tooth of Fig. 53. Tooth of Fig. 54. Tooth of Ceslracion. Hybodon. true Shark. 18. EXTENT or THE COAL-MEASURES. It is evident that the coal formation cannot be found except above the Cambrian, Silurian and Devonian strata, which were formed anteriorly to, or about the time of these deposites. If it existed before that period, it must be necessarily concealed by aU the strata subsequently formed, and searches have been extended below them at great expense for this combustible. The consequence is, that the coal formation occupies a small portion of the uncovered surface of the earth. Ah 1 the depo- sites known in France do not occupy more than one two-hundredth part of the superficies of the territory. England and Belgium are comparatively richer, for in the first the surface of the coal forma- tion is equal to one-twentieth of the whole kingdom, and in the second to one tAventy-fourth. Ah 1 the other States of Europe are much poorer, and some, Sweden, Norway, Russia, Italy and Greece, are almost entirely without this valuable formation. Bohemia is the richest part of Germany in coal, although it does not produce largely. The northern part of the Spanish peninsula seems to contain considerable deposites of coal, and to participate, in this respect, in the wealth of Western Europe. 19. The coal-fields of the United States are numerous and ex- tensive. Coal is found in Massachusetts, Rhode Island, Pennsyl- vania, Maryland, Virginia, Ohio, Kentucky, Tennessee, Illinois, Alabama, Mississippi, and Indiana ; in a word, the coal formation in the United States is greater than in any country or kingdom on the face of the earth, and embraces every variety hitherto disco- vered. 20. The different layers, constituting the coal-measures, were deposited horizontally at the bottom of the basins they occupy, but they have not remained in this position ; at certain places they 17. What does the existence of the genus unio in the coal-beds indicate? 18. What is the relative geological position of the coal-measures? 19. In what parts of the United States do we find coal ? 46 COAL FORMATION. were raised up, and at others lowered down, so that they became more or less oblique, and often seem to be, as it were, folded on themselves ; it is also remarked that frequently a certain extent of the mass formed by these layers has been sepa- rated from neighboring parts by a sort of split or cleft, and elevated or de- pressed to a different level ; conse- Fig. 55. Fault. quently the beds of coal are suddenly interrupted at these points, and are found further on at a different height. These geological accidents are designated by miners under the name of faults, (Jig. 55). Speaking of the origin and nature of coal, Dr. Buckland remarks, " The most early stage to which we can carry b 81), some of which were twenty-five feet in length; the Plei'sio- sau'rus, (fig. 82), some species of which are nearly fifteen feet long. 38. Are any species of Trigo'nia characteristic of any part of the Lias ? 39. What is an Ich'thyosau'rus ? What is the lowest stratum in which it is found ? What is the Plei'siosau'rus ? FOSSILS OF LIASSIC SYSTEM. 57 The I'CHTIIYOSAU'RUS (from the Greek ichthus, a fish, and sauros, a lizard fish-lizard Jig. 81), must have resembled some huge fish, having an exceedingly large head and very powerful tail. The spine consisted of 120 Fig. 81. I'chtliyosau'rus communis. vertebrse or joints, besides those of the neck, which were united into a mass of solid bone. The eye was an extremely powerful organ, " capable of adapting itself," says Dr. Buckland, "to great changes of distance, and great alterations in the amount of light in which it could be used ; giving to its possessor the power of discerning a far-distant object, as well as one near at hand, and of pursuing its prey in the darkness of night, or the dim obscurity of the depths of the ocean, as well as in the day-time or on land." This animal had a wrinkled skin, like the whale, without scales. Fig. S2. Plei'siosau'rus dolichodeirus. The PLEI'SIOSAU'RUS (from the Greek plesion, near, and sauros, a lizard or reptile resembling a reptile -Jig. 82) may be described as exhibiting the head of a lizard, attached to a neck whose length was three, or, in some species, even more than four times that of the head. The body appended to this head and neck was comparatively small and fish-like ; the extremities were large paddles, and the tail like that of the crocodile. The neck con- sisted of upwards of thirty vertebrae or joints, and was very long and flex- ible. Ansted. Fig. 83. Pteroda 'ctylus longiro'stris. 40. We also find, for the first time, in the lia'ssic group, the pterodac'lylus (from the Greek pteron, wing, and daklulos, finger- 58 JURASSIC OR OOLITIC SYSTEM. fig. 83), a flying saurian, whose head and neck gave it the semblance of a bird, and its tail was like that of a mammal, while its extremities were analogous to those of a bat ; it was capable of walking and flying, and, perhaps, of climbing steep rocks in pursuit of food. 41. With the remains of these singular animals are found, in the lias of Lime-Regis, on the coast of Dorset, England, an immense quantity of coprolites (from the Greek kopros, dung, and lithos, stone), which probably belonged to them : sometimes their intes- tines are found in their skeletons ; and we also find, in these, the remains of fishes and other reptiles, clearly showing how the aquatic species were nourished. The remains of insects are found with those of the pteroda'ctyli at Solenhofen, in Franconia, also showing what was the food of these animals. 42. Saurians resembling crocodiles were much less abundant in this epoch, although we find, in the lias, remains which prove their existence. The me'galosau'rus (from the Greek me gas, great, and sauros, reptile) partook of the nature of the crocodile and monitor, and must have been from fifty to sixty feet in length. 43. Ink-bags of considerable size (Jig. 84), ana- logous to those of the cuttle-fish, are also found. In the lias of Lime-Regis, the dorsal bones of the calmar are also met, with other traces of this genus, as well as of belemni'tes. The ink or se'pia, which may be obtained from these fossils, is as good as that pre- pared from the recent cuttle-fish, and has been used. 44. THE JURA/SSIC OR O'OLITIC SYSTEM. O'olite (from the Greek don, an egg, and lithos, a stone), is a granular variety of carbonate of lime, frequently called roe-stone, from its resemblance to a fish-roe, or egg-bag. The frequency of the occurrence of this particular .. Ink- / i- ^ i i bag. form of limestone in a great series of deposits, has caused the name of o'olitic to be applied to the whole series. 45. The o'olitic or jura'ssic deposits (the Jura-kalk of German geologists), are divided into several groups, which are distinguisha- ble from each other by their relative position in the scale of eleva- tion, but more particularly by the fossils found in them ; the re- mains which are characteristic of the preceding groups, are not met with in this. The o'olite is divided into the lower, middle, and upper o'olites. 46. The lower o'olite, the first in the series of o'olitic deposits, 40. What is a Pteroda'ctylus ? Where is it found ? 41. What was, probably, the food of the Pteroda'ctylus ? 42. What was the Me'galosau'rus ? 43. What other fossil substances are found in lias ? 44. What is o'olite ? 45. How is the o'olitic system divided ? How are the divisions recognised ? 46. Of what does the lower o'olite consist? By what fossil is it charac- terized ? FOSSILS OF THE OOLITE. 59 consists at first of layers of marl intermixed with sand, then layers of ferru'ginous o'olites, and strata of compact limestone and clays, more or less pure and fitted for the purposes of the fuller, and hence named/w//ers' earth. The first of these marly deposits joins with the marls of the lias, but is characterized by a new species of gryphae'a (Jig. 85), which is not found in the preceding layers. 47. Above these deposits are found fissile marls, lime- stone, with ferru'ginous o'olite ; to which succeed earthy de- posits, the great o'olite, which consists of a variable series of coarse shelly limestone (lo- cally called "rag"), alternat- ing with beds of fine soft free- stone, devoid of fossils, and admirably adapted for building purposes. Above these again come marls, sands, clays, and limestones, some of which are full of shells. They are known under the names of Bradford day, Forest marble, and Corn- brash. In spite of the num- ber of fossils, often broken and in the state of moulds, found in this group, it is difficult to designate those which are cer- tainly characteristic of it. Fig. 85.Grypha'a cym'frium. 48. To the Gryphae'a cym'bium (Jig. 85), which is characteristic of the first group of the o'olitic deposit, and forming, as it were, a new geognostic horizon, we may add the O'strea acumina'ta (Jig. 86), Fig. 87. Terelra'tula digo'na. Fig. 86. O'strea acumina'ta. 47. What is found above the lower o'olite ? 60 FOSSILS OF THE OOLITE. which is found in the upper marls, or limestones sometimes met with in their place : different species of Terebra'tula (Jigs. 88, 89), Terebrat.globa'ta. FigSQ. Tereb. spino'sa. Fig.QQ. Ammonites Brongnia' rtii. which seem to belong more particularly to the lower o'olite, as well as a small globose species of ammonites (fig. 90). 49. In the limestones proper, different species of ammonites (fig. 91) are found; various species of pleurotoma'ria (fig. 92), Fig. 91. Ammonites stria' lulus. Fig. 92. Pleuroloma'ria cono'idea. which seem to be characteristic, and a great number of shells of divers kinds, are met with. Encrini'tes, frequently very nume- rous, which are chiefly referred to the pyriform species, apiocri'- nites, are sometimes found on the very spot where they lived, attached to the solid materials forming the bottom of the sea of that epoch, and covered by successive deposits of the earthy matter of which it was constituted. 50. An important fact is connected with the marls and fissile limestones which form the first of the o'olite system : the first, or most ancient fossil mammals, were discovered in Stonefield slates. 48. What fossils are characteristic of the o'olite ? 49. What fossils are found in the limestone proper of the o'olite scries ? 50. What important fact is connected with the fissile limestone and marls of the lower o'olite ? FOSSILS OF THE O'OLITE. 61 These small ani- mals, the lower jaw of one of which is repre- sented (fig. 93), belong to the mar- supials ; that is, one of the most imperfect orders Of the Class. Fig.W.JawoftheDide'lph Bones of large animals, thought to belong to the order of ceta' cea, are also found in the o'oli- tic strata. 51. Con'ifers, which are but rarely found beyond the shell- limestones, are abundantly met with in the o'olite series, of particular genera (Jig. 94), with Cyca'dete (Jig. 95) ferns of different species, dif- fering from all those met in more ancient strata, and finally a true equisetum (fig. 96). \ Buckla'ndii (twice the natural size'). Fig.95. Ptero 'pJiyllum Williamso'nis. 51. What fossil plants are found in the lower o'olite ? 6 62 FOSSILS OF THE O'OLITE. 52. MIDDLE O'OLITE. This group, which is less complicated than the preceding, at the lowest part consists of clay, called Oxford clay, with layers of calcareous grit, and stratoid masses of lime- stone. Above these are found sands, and limestones which are more or less o'olitic, and often ferru'ginous. In this group we find deposits of o'olitic iron, which had already appeared in the pre- ceding series. It is very rich in fossils, particularly ammonites ; and the Jinanchy'tes bicorda'tus (fig. 97) is very common. Fig. 97. Ananchy'tes licorda'lus. Ananchy'tes is a genus of the family of Echini'dese, or sea-urchins, some- times vulgarly called sea-eggs. The family contains thirteen genera, which are distinguished from each other by the form and size of the ambula'cra, (alleys) the narrow longitudinal portions of the shell of the echinus or sea- urchin, which are perforated with a number of small orifices, giving pas- sage to tentacular suckers, and alternate with the broad tuberculate spine- bearing portions (see Jig. 70) and also by the position of the vent, and of the mouth. Figure 70, p. 54, exhibits the ambula'cra, between the tubercles to which the spines are attached in living species. 53. What especially characterizes the Oxford clays is the pre- sence, often in abundance, of a new species of Grypnae'a (Jig- 98), Fig. 98. Gryplia'a dilata'ta. Fig. 99. 0' street Ma'rskii. Fig. 101, Tcrebra'tula impre'ssa. the O'strea Ma'rshii (fig. 99), which already commenced in the preceding group, a great number of different terebra'tula, among 52. Of what does the middle o'olite consist ? What fossils belong to it? 53. How are the Oxford clays especially characterized ? FOSSILS OF THE O'OLITE. 63 which we find in the upper part of the series, the Terebra'tula Thurmanni (Jig. 100), and the Terebra'tula impressa (fig. 101). The moulds of these shells are frequently silicious, and we find, in the upper layers, beds of silicious balls of loose texture, some- times enclosing silicious moulds of shells. 54. The upper group of the middle o'olite, called coral o'olite, consists almost entirely of limestone ; it is divided into different thick layers, which are distinguishable from each other by their structure. The first or lowest layers are ordinarily compact, grey- ish or yellowish, filled with polypa'ria or corals of a sac'charoid structure, or those which have passed to the silicious state : this constitutes the coral rag of English geologists. Some of the succeeding layers are o'olitic, frequently of large irregular grains, mingled with fragments of rolled shells ; others are compact, pass- ing into chalk or even marl of greater or less solidity. 55. The numerous polypa'ria contained in this group present to us caryophy'llia (fig. 21), a'strea, meandri'na, madrepores of a great number of species, resembling more or less those of coral reefs, and a great many other genera. Among the shells, ammo- nites are less common ; but above the o'olite, where all the organic remains are broken, the lowest layers contain a great quantity of various shells, among which are neri'nea (figs. 102, 103). The Fig. 102. Neri'nea Goodhallii. Interior of the shell, showing the plic& of its colum'nella. fig. 103. Neri'nea mosa. superior strata contain a great quantity of astarles (figs. 104, 105), the most characteristic of which is the astarte minima. 54. What are the characters of the upper group of the middle o'olite ? What is coral rag 55. What genera of corals are found in the middle o'olitc ? What fossil Shells do we find in this group ? 64 FOSSILS OF THE O'OLITE. Fig. 104. Astartemi'nima. Fig. 105. Astarte elegans. Among other shells, we may cite the Dicefras arieti'na 106) ; and among the echi'noderms, the cida'ris corona'ta (fig- Fig. 106. Mould and shell of the Dice 'r as arieti'na. Fig. 101. Cida'ris corona'ta. 56. UPPER O'OLITE. This group is divided into Kimmeridge clay, and Portland o'olite. Kimmeridge clay, (so named because it is well exhibited at Kimmeridge Bay, and near the village of the same name, in the isle of Purbeck \, is of a blue, slaty, or grey- ish yellow colour. Above this is the Portland stone, which, with alternations of compact, marly, sandy or o'olitic limestones, termi- nates the Jura'ssic or o'olitic system. 57. The organic remains which characterize this group are of the genera ostrea, and ex'ogy'ra of particular species (figs. 108, 109), sometimes in great abundance. Witk a few ammonites, we also find mya (fig. Ill), Pholadomy'a (fig. 110}, and Terebra'tula (fig. 112), which are also equally characteristic. Certain beds of this formation contain Paludi'nse, or Helices, consequently indi- cating that streams of fresh water emptied into the seas of that period. 56. How is the upper o'olite divided? What is Kimmeridge What is found above the Kimmeridge clay ? 57. What fossils are characteristic of the upper o'olite ? FOSSILS OF THE O'OLITE. 65 Fig. 108. O'strea del to'idea. Fig. HQ.Pholadomy'a a'cutico'sta. Fig. IQ9.Ex'ogy'ra vir'gula. 58. The lithographic stone of Solenhofen, in Bavaria, is referred to the upper strata of the Jura'ssic system ; in it are found an im- mense quantity of fossils, reptiles, particularly, pterodactyls, fishes, insects, plants, &c. In some parts of upper o'olite are beds of a highly bituminous shale (locally known as Kimmeridge coal); 'in the latest calcareous beds of the Portland group are found cyca'dex Fig. 112. Tere.bra'tula sella. Fig. 113. Za'mia feneo'nis. 59. The o'olitic or Jura'ssic system of rocks is met with in Eng- land and on the continent of Europe, but is not represented in North America, where the transition from the new red sandstone to the greensand and other rocks of the creta'ceous period is abrupt. No rock answering to the Lias has yet been discovered in the United States. 58. To what geological group does the lithographic stone of Solenhofen belong ? What is Kimmeridge coal ? 59. In what part of the world is the o'olitic system of rocks found ? Is it known in the United States ? 6* SIXTH GEOLOGICAL EPOCH. LESSON IV. SECONDARY FORMATION Continued. SIXTH GEOLOGICAL EPOCH. Creta'ceous Formation Lower Cre- ta'ceous System Fossils Wealden Deposit Greensand Gault Fossils Upper Creta'ceous System Fossils Extent of Creta'ceous Formation Table of Formations. SIXTH GEOLOGICAL EPOCH. CRETA'CEOUS FORMATION. (Secondary Formation Continued.} 1. Next in order above the Jura'ssic system we find, in discord- ant stratification, immense Creta'ceous deposits in a great many lo- calities ; these deposits may be divided into several others, accord- ing to the discordance of stratification observed in some of their divisions. The Creta'ceous formation (from the Latin, cre/a, chalk) may be divided into the upper and lower chalk. 2. The LOWER, or INFERIOR CRETA'CEOUS system : Neocomian of the French ; the Shanklin, or Lower Green Sand of the Eng- lish. The first deposits formed above the o'olite are composed of marls, then a yellowish limestone, characterized by great numbers of genus Spata'ngus (Jig. 114), with a multitude of the remains of shells and polypa'na of different genera. This limestone is sometimes in continuous layers of considerable thickness, some- Fig. 114.- Spata'ngus Fig. 115. Exo'gy'ra Fig. 116. Lima retusus. subplica'ta. elegans. 1. What is found next above the Jurassic formation? Why is it termed Creta'ceous ? How is the creta'ceous group divided ? 2. How are the first deposits above the o'olite characterized ? What is lumachella ? What is found next above the yellow limestone ? CRETACEOUS FORMATION. 67 times only in masses agglutinated to each other by mud and sand ; sometimes it is entirely wanting. Above it are clays which con- tain, often in great quantity, ex'ogy'ra (Jig' 115), and oysters, among which is distinguished the great species, named Ostrea Leymerii ; the Lima elegans (Jig- 116) is also found. Among these clays are met large calcareous masses, a good deal flattened, filled with the same fossil sheDs, presenting tumachdla* or conchi- lians, which have been confounded with the Portland group, form- ed by an accumulation of the ex'ogy'ra vi'rgula (fig. 109). Next we have, at least in parts of France, sands and clays, sometimes variegated in colours, among which are masses of iron ore, com- monly o'olitic. The remains of shells seem to give place here to ferruginous masses. 3. These last deposits seem to be wanting in other localities, in which we find, instead, great layers of limestone, more or less compact, sometimes white, sometimes coloured, which enclose hippuri'tes,spheruli'tes,and even nummuli'tes, which have been long regarded as belonging to the tertiary formation. We also find here a fossil which is very characteristic ; it was at first compared to the diceras (Jig. 106), but is now call- ed Chama ammonia (fig. 117). This species of shell, which is often very abundant, is always so imbedded in the mass of rock, where it is dis- tinguished by the sinuosities Fi S- H7- Cha'ma ammo'nia. it forms, that it is very difficult to detach it entire. Various spe- cies of ammonites, gigantic hamites, several species of Crio'ceratites (fig. 118 from the Greek, Krios, a ram, and Keras, horn) and belem- nites. The trigo'nise, which are still met with and continued to the green- sand, present here new species (fig. 119), which seem to be characteris- tic. 4. In the south of France and in the Pyrenees the chalk formation Fig. us * Lumachella an Italian word, formed from limacea, a snail, which is derived from the Latin, Umax. The word is used to designate a mass formed of the remains of snails, &c. with their nacre, united by gluten It is also called conchilian marble. 3. Are sands and clays everywhere found above the yellowish limestone? What fossils are found in these limestones of the creta'ccous group? 68 CRETACEOUS FORMATION. (View of Hinge.} Fig. 119. Trigo'nia a'l&for'rnis. possesses peculiar characters, both in relation to the organic re- mains contained in it, as well as its mineralogical relations. We there find a great many shells, very remarkable for their form and peculiar structure, which are called hippuri'tes (figs. 120, 121), ^wggrT^ and spheruli'tes (fie;. 122). Many nummuli'tes (fig. 123), of which some deposits are formed exclusively, are also met with. It is not determined pre- cisely to what part of the lower chalk these deposits should be referred, but Fig. 1 20. Hippuri't es lio'culata. Fig. 1 2 1 .Hippuri'tes orga'nisans. 4. How is the chalk formation characterized in the south of France ? "What are Hippurites ? THE WEALDEN DEPOSIT. they seem to represent a part of the neocomian (or Shanklin) for- mation. In the Pyrenees the lay- ers are often of a deep colour, and separated by argilla'ceous schists, which seems to make them a part of the transition for- mation ; but, on the contrary, in the north part of the ba-sin of the Gironde, they belong to the chalk. 5. The neocomian, which was not at first distinguished from other parts of the chalk forma- tion, is now recognized in a Fig. 1%2,Spkcruli teg ventricosi Radiuli' te.-< lurbina'ta. Fig. 123. Nummuli'tes from the chalk. great part of France, Switzerland, and different parts of Germany, Poland, and even to the Crimea. Here and there deposits of gyp- sum of greater or less extent are met with, sometimes isolated, and sometimes associated with crystalline rocks. 6. The WEALDEN DEPOSIT. We frequently meet in the first deposits of the chalk formation the remains of organized bodies, which appear to belong to paludi'nse, clearly showing there was here and there an afflux of fresh water to those seas in which these remains accumulated. We also find in the same situations deposits of combustibles, which have always been known under the name of lignite (from the Latin, lignum, wood), probably form- ed from con'ifers (as dicoty'ledons did not then exist), which were doubtlessly carried by rivers : such are those in the environs of Orthez, in the department of Landes ; of Bellesta and of Saint-Girons, in the department of Ariege ; of Irun, in Guipuscoa (Spain), &c. But all these local deposits are nothing compared to those which have long been described in England, in parts of the counties of Kent, Surrey, and Sussex, under the name of wealds, from which is derived the term wealden formation. 5. What is the Neocomian deposit ? What is its extent ? 6. What is meant by Wealden formation ? Why is it so called ? 70 THE WEALDEN DEPOSIT. 7. This formation is composed of alternate layers of limestone, sand, more or less ferru'ginous, and clay, the deposits of which are sometimes extremely thick. There are .entire beds of limestone composed of paludi'nre, constituting what' is named Purbeck lime- stone. The lamina? of argilla'ceous matter are often covered by cy'clades and anodo'ntse, and we find disseminated a great number of small cypris. TJiere are many species of fresh water fishes, the remains of fluviatile tortoises, mingled with marine and terres- trial saurians, among which is the monstrous i'guanodon, which must have been thirty feet in length, to judge from the size of its bones. In this formation are found also, in the dirt of the Isle of Portland, the sili'cified stems of cyca'dere (fig. 124), standing erect in the midst of the earth, of which the deposit consists ; various species of conifers, equi- sita'ceoe, and ferns are also met. The remains of birds of the order Fig. 124. Mante'Llia nidifo'rmis. of gra'lleas (waders)also exist, but no mammals, although we have seen them in the marls of the o'olite (Jigs. 81, 82). 8. It is believed that the clays in the environs of Boulogne, which seem to be continuous with those of England on the south- ern side of the Channel, may be referred to the wealden deposit, as well as those of Forges and of Savigny in the country of Bray, where paludine limestones like those of Purbeck have been found. It is very certain, according to the observations of M. Leymerie, these deposits are connected with those in the department of Aube, and form part of the superior neocomian clays : if there are indi- cations of fresh water deposits, they prove the connection between the wealden formations and those of this epoch. 9. According to English geologists, the wealden formation is below the neocomian, and is, consequently, older and not precisely contemporaneous with it. 10. Above the neocomian and wealden formations there is a group of deposits generally termed Green Sand, consisting of two arena'ceous beds, with a parting of clay called gaidt. The green sand formation receives its name from the prevalence of small green particles of si'licate of iron distributed through the sand. It is found in New Jersey. In England it is divided into lower green sand, gault, and upper green sand. This group consists of white 7. What is Purbeck limestone ? 8. What is the extent of the Wealden formation ? 9. Which deposit lies above, the Neocomian or Wealden ? 10. What is found next above the Wealden and Neocomian ? From what does green sand obtain its name ? How is it divided ? GREEN SAND. GAULT. 71 and yellowish sands, which are frequently ferruginous, containing masses of limestone, clays, and sandstones of more or less com- pactness : it also comprises the quadersandstein and plxmr-kalk of German geologists. 11. Gault is a stiff clay of a blue colour, and the inferior por- tion of it in England abounds in iron py'rites, while the upper part contains green particles of the silicate of iron. Various nodules and concretions are found throughout, which are sometimes fossili'- ferous, but more frequently obscure and of doubtful origin. Gault is a provincial term, used originally in the middle of England to designate the brick-clay, which there belongs to the creta'ceous system. 12. Above the green sand formation, the calcareous part be- comes more abundant ; at first it is mixed with sandstone, and then, little by little, becomes isolated, and now contains only green parti- cles of si'licate of iron, which, from being at first very abundant, gradually disappear : this is the chloritic chalk, which is some- times friable, and at others solid. The green particles having totally disappeared, the limestone is found alone, sometimes in form of pure chalk, of more or less solidity, and occasionally becomes very compact ; here we have argilla'ceous or arena'ceous limestone, and finally sands, or nearly pure sandstone. From these result the chalk marlj or representatives of it. 13. Organic remains are in very abundant these deposits, and in species and even in ge- nera are very distinct from those of the preced- ing formations. Immedi- ately above the wealden is a marly bed, charac- terized by the presence of a species of Ex'ogy' ra (Jig> 125) five or six inches in diameter, not known in the neo- comian. According to M . Leymerie, the nu'- cula pectina'ta (fig> 126) is a characteristic shell of the gault or blue Fig. 125. Ex'ogy'ra sinua'ta. marl. Belonging to the green sand 11. What is gault ? What is the origin of the name ? 12. What succeeds the green sand formation ? What is chloritic chalk ? What is chalk marl ? 13. What organic remains are found in these deposits ? 72 FOSSILS. formation generally, the characteristic shells are the inoce'ramus conce'ntricus (fig. 127), the plica'tula placu'nea (Jig- 128), seve- ral species of ammonites, and particularly the ammonites monile (Jig- 129), which is quite characteristic. Fig. 127. Jnoce ramus con- ce'ntricus. Fig. 126. JWcw/a pcctina'ta (.skell and mould). Fig. l"Xi.Scnplii'tes e'qualis. Fig. 128. Plica'tula placu'nea. 14. We find in the chalk marl the bacilli' tes (fig. 130), and turrili'tes (fig. 131), different species of the first of which are found in the highest part of the chalk formation. To these may be added the scaphi'tes (fig- 132), some particular species of Fig. 129. Ammonites moniU. Fig.lZQ.Baculi'tes. ammonites (figs. 133, 134), the Ex'ogy'ra columba (fig. 135), the O'strea carina'ta (fig. 136), the terebra'tula octo'plica'ta (Jig. 137), which continue in "the chalk. 14. What animal remains are found in the chalk marl ? FOSSILS. 73 Fig. 134. Ammonites rotkomage'nsis: Fig. 135. Ex'ogy'ra columba. Fig. 137. Tcrcbra'tula octo'plica 1 ta. Nu'cula (from the Latin, nux, a nut) is an inequilateral bivalve shell; the hinge is narrow, and has many teeth like those of a comb : several species are known. Scaphi'ics (from the Greek, scaphe, a boat) is an eliptical, many cham- bered shell, somewhat resembling the ammonites. Ba'culiles (from the Latin, ba'culum, a stick) is a multilocular, straight, or slightly bent, and slightly conical shell ; the chambers are separated by septa, pierced by a marginal siphuncle. Turrili'tes is a spiral, turriculated, multilocurlar shell; the chambers are separated by winding septa, which have the si'phuncle in their disks : the aperture is round. This fossil must not be confounded with the Turrite'lla, which is a univalve, found both recent and fossil. 15. The Upper Chalk Formation. In this we find chalk with and without flints. The layers of flint are frequently almost the only indications of stratification afforded by the mass. It is fre- quently soft, and susceptible of solution or suspension, as in Spa- nish whiting, which contains an immense quantity of microscopic shells, belonging to the group of foraminifera. In some cases it is arena'ceous, and sometimes very compact. Although often white, we find it in some places coloured grey, yellow, red, &c. ; 15. How is the upper chalk formation characterized ? 7 74 UPPER CHALK FORMATIONS. sometimes it is o'olitic in character, and becomes almost crystalline, even magnesian, and in localities remote from crystalline materials which might affect it. The inferior part of this formation is fre- quently soiled with clays chalk marl. Above it is more pure, and contains a great many nodules of flint or silex. Though this character is very common, it is wanting in a great many places. At its upper part the chalk formation becomes very sandy, as in the neighbourhood of Maestricht. 16. Excepting the ba'culites found at Maestricht, the remains of cephalopods are not found in the upper creta'ceous formation ; but belemni'tes (from the Greek, belem'non, a dart) of particular species, such as Jig. 138, and many other organic remains not Fig. 138. Belemni'tes mucrona'tus. met with in the chalk marl, are found : among them are the pla- gio'stoma spino'sum (fig. 139) ; the o'strea vesicitla'ris (fig. 140) ; Fig. 139. Plagio'stoma spino'sum. Fig. 140. O'strea vesicula'ris. the Ca'tylus Cuvieri (fig. 141), the structure of which is fibrous ; the Terebra'tula Defra'ncii (fig. 142) ; the ana'nchytes ova'tus (Jig. 143) ; the Spa'tangus cor-ari guinum (fig. 144). Fig. 141. Ca'tylus Cuvieri. Fig. 142. Terebra'tula Defra'ncii. 16. What organic remains are found in the chalk formation ? UPPER CHALK FORMATIONS. 75 . 143. Ana'nchytes ova'tus. Fig. 144. Spa'tangus cor.an guinum. 17. In the upper part of these deposits we find, among many other fossils, an enormous saurian, called the Mosasaurus (from the name of the river Meuse, and the Greek, sauros, lizard), originally found on the banks of the Meuse, in the celebrated quarries of St. Peter's Mount, near Maastricht (Jig. 145). Organic remains of a Mosasaurus have been found in New Jersey. Fig. 145. Head of the Mosasaurus of Maastricht. " The Mosasaurus is a genus determined from a fossil discovered upwards of sixty years ago, and which at that time was extremely puzzling to natu- ralists. Its true place in the animal kingdom is now known to be among the Lacertian Saurians; but the animal appears to have been perfectly ma- rine in its habits. The head, the only part at first discovered, measured 7. Where is the Mosasaurus found ? From what is its name derived ? 76 CRETACEOUS GROUP. four feet in length, and is preserved in the museum at Paris. Other paits have also been found from time to time in the Maastricht quarries, and some fragments in the chalk of the south of England." Ansted. The whole length of the animal was probably not less than twenty-four feet, a magnitude which must be compared with that of the lizards of the present day, and not with the crocodilians, whose structure is totally dif- ferent. 18. We also find in the chalk formation ceta'ceous mammals, which are classed among the lamantins and dolphins. 19. The CRETA'CEOUS GROUP prevails extensively in England and on the continent of Europe. True white chalk exists not only in England, but also in France, in Denmark, in Poland, in central Russia, and in the Caucasus. Semicrystalline rocks of the creta'ceous epoch also exist in the central plains of Asia Minor. Beds of the creta'ceous period are found in New Jersey, and other parts of the United States ; but they rest on the oldest secondary- rocks, without the intervention of the o'olite. The formation is extremely calcareous, in places chiefly arenaceous, but no true chalk has yet been discovered in America ; nor has o'olite been found. Fossils, apparently creta'ceous, have been recently obtained from south-eastern India. '" This brings us up to the close of the secondary formation. As far as we have studied our subject, we find the earth's crust to con- sist of a series of formations, as represented in the following dia- gram (fig. 146). Secondary . Chalk with flints. Chalk without flii Chalk marl. Green sands. Wealden. O'olitic System. Cretaceous Systt Liassic System. Upper new red sandstone, orTriassic System. Lower new red sandstone, or Permian System. Carboniferous System. Old red sandstone. Transition. Metamorphic. Plutonic Rocks. f Devonian System. Silurian System. ambrian System. Argillaceous Schist. Mica Schist. Granite. Fig. 146. 18. What mammals are found in the chalk formation ? 19. What is the extent of the creta'ceous group ? Has chalk been found in the creta'ceous formation of the United States ? SEVENTH GEOLOGICAL EPOCH. 77 The study of the creta'ceous rocks brings us, as it were, to the termination of that period in the history of the earth's structure to which the character of antiquity belongs. In the succeeding period, we shall find all the fossils are either resemblances or types of existing organic creatures. LESSON V. SEVENTH GEOLOGICAL EPOCH. Tertiary Formation Eocene beds Paris Basin Fossils Jlnoploihe'rium Paleothe'rium Miocene beds Dinothe'rium Lignites Pliocene beds- Fossils Bone Caverns. SUPERFICIAL DEPOSITS. Drift Diluvium Megathe'rium Boulder Formation Alluvium Big Bone Lick. EIGHTH GEOLOGICAL EPOCH. Modern Formation. SEVENTH GEOLOGICAL EPOCH. TERTIARY FORMATION. 1. Ordinarily, geologists designate under the collective name of SECONDARY FORMATION, the long series of systems of rocks, com- mencing above the transition formation with old red sandstone and coal (fig. 146), and terminating above with the chalk ; and they give the name of TERTIARY FORMATION to those strata which are more recent than the chalk, and consequently superior to it, but still more ancient than the strata of the present or modern epoch. 2. During that period the seas were very much less extensive than they were in the more remote geological ages, and conse- quently the sedimentary deposits formed in those waters are of less extent and more isolated. Moreover, their formation was effected at different points of the globe, and at different periods, and to fol- low their history in chronological order, it is necessary to subdivide them into three groups. At the period contemporaneous with the deposit of each one of these series of formations, there existed particular species of organized creatures, mingled with other spe- cies like the preceding or succeeding periods ; but the fauna of all the divisions of this period possesses certain common characters, and among the most remarkable of these is the existence of a great number of mammals. i 1. What is understood by secondary formation ? What is meant by ter- tiary formation? 2. How did the seas of the tertiary epoch differ from those of more re- mote geological ages ? What is the most remarkable characteristic of the tertiary formation ? 7* 78 TERTIARY FORMATION. 3. The Tertiary Formation is divided into the older, middle, and newer tertiary groups, which have been conveniently designated by Mr. Lyell under the names of Eocene, Miocene, and Pliocene. The first, EOCENE (from the Greek, eos, dawn, and kainos, recent), designates the older tertiary strata, in which there appears, as it were, the first dawn of existing species. The second, MIOCENE (from the Greek, melon, less, and kainos, recent), is applied to the middle tertiary strata, because in them we find more recent species than in the preceding group, but still fewer recent than extinct species. The third, PLIOCENE (from the Greek, pleibn, more, and kainos, recent), is given to the newer tertiary beds, because there is always a greater number of recent than of extinct species found in them. 4. The Eocene, or older tertiaries. The beds thus designated are a very variable series, consisting, in England and Belgium, of stiff clays alternating with sand, and resting on coarse sand and gravel ; and, in Paris, of a number of limestones and marls, alter- nating with gypsum and silicious strata. They are deposited in basin-shaped depressions in the older rocks, and in England some portion of them has been so greatly disturbed, that the beds are actually vertical. 5. The older tertiaries of England are chiefly confined to three masses, contained in trough-shaped basins, called respectively, the . London, the Hampshire, and Isle of Wight basins ; a stiff clay predominates in them, and, from being very abundant near Lon- don, is known as the " London day''' The London clay often, but not always, rests on a series of sandy and gravelly beds, in- closing bands of potters' clay, to which the name of Plastic clay has been given. 6. The greatest development of eocene strata in the United States occurs in Virginia, North and South Carolina, Georgia, and Alabama. In Virginia these beds consist of greenish sands, nearly identical in appearance with a portion of the creta'ceous series, and of the same mineral composition ; and a little further to the south a continuous formation of white limestone ("Santee limestone") occurs, which is of no great thickness, and which varies in hard- ness, and is composed of comminuted shells, but so closely resem- bling certain creta'ceous beds of the secondary period in New Jer- sey, as to have been frequently mistaken for them. But this resemblance does not extend to the fossil contents of the beds, 3. How is the tertiary period divided? What is meant by Eocene? What by Miocene ? What by Pliocene ? 4. What are the characters of the Eocene beds ? How are they de- posited ? 5. What are the chief localities of Eocene beds in England ? What is London clay ? 6. In what parts of the United States do Eocene strata exist? TERTIARY FORMATION. PARIS BASIN. 79 which are in many instances analogous, or the same as those of the eocene formations in other parts of the world. 7. The geological position of the city of Paris resembles that of London, each being situated upon an extensive and important group of tertiary strata, which occupies a depression or basin in the underlying chalk. The nature of the two deposits is, how- ever, totally different, the deposit being characterized in England by great accumulations of argillaceous matter, which form the London clay, while in the neighbourhood of Paris there is a varied series of limestones and marls, alternating with important beds of gypsum and silicious matter. 8. The depression in the chalk forming the celebrated Paris basin so frequently named by geologists, which is filled up by these strata, is nearly one hundred and eighty miles in its greatest length, and about half that in breadth. The surface of the chalk is usually covered by broken and rolled flints, often cemented by a silicious sand into a kind of breccia; and these flints seem to mark the action of the sea upon reefs of chalk before the commencement of the tertiary epoch. The order of stratification of the Paris basin is represented in the following table. 8. Upper marine sands. 7. Upper fresh water sands. W- y, ' 6. Green marls. 5. Gypsum. i { Calcaire siliceux, or o ( Calcaire grossier, or ' ( Fresh water limestone. ' I Marine limestone. 2. Plastic clay. 1. Chalk. 9. Above the chalk we find, first, deposits of plastic clay, so called because varieties of it are well suited for the manufacture of pottery. In the neighbourhood of Montereau on one side, be- tween Houdan and Dreux on the other, it is remarkable for its whiteness and purity, and is used in the fabrication of the finest porcelain. Around Paris it is coloured and impure, and suitable only for coarse pottery. These clays contain lignite, in which we see, perhaps for the first time, mingled with numerous co'nifers, phanero'gamous monocotyledons, true palms, and some dicotyle- dons. Marine, as well as fresh water shells, are found in its upper part. 7. In what respects does the geological position of Paris differ from that of London. 8. What is the extent of the Paris basin ? 9. What lies next above the chalk in the Paris basin ? What are the characters of plastic clay ? To what uses is it applied ? 80 TERTIARY FORMATION PARIS BASIN. 10. Above the plastic clay we find thick deposits of marine limestones, more or less arena- ceous in structure, the different beds of which may be easily distinguished by their characters. These limestones contain a pro- digious quantity of mil'liolites (fig> 147) extremely small Fig. 147. Mil'liolites (greatly mag- nified). shells the most of which do not attain .03937 of an inch in size, and yet they constitute a great number of genera. These serve, in a manner, as paste to an immense number of shells of different genera, which are more analogous to creatures now living than any we have hither- to mentioned : three per cent, of them are even identical with species now existing in the neighbouring seas. The cerithia are here so abundant that the formation is sometimes known by the name of cerithia lime- stone, although these same fos- sils are found in many other de- posits. There are certain spe- cies which are characteristic, that is, they are always found wherever these deposits exist : such, for example, is the Ceri'- thium giga'nteum (fig* 148), Fig. 148. Ceri'thium giga nteum (very much reduced). 10. What lies above the plastic clay ? What are mil'liolites ? What proportion of fossil shells found in eocene strata resemble living species ? What is Cerithia limestone ? FOSSILS. PARIS BASIN. sometimes twenty-seven inches in length, the extremity of which is almost always worn or broken by the friction and knocks occa- sioned by the movement of the animal. Among other shells, of which there are a great many species, it is difficult to name any which are absolutely characteristic ; among the most common are the Turrite'lla imbrica- ta'ria (Jig. 149); the ampulla' ria acuta (fig- 150) ; the terebe'llum fusifo'rme, (fig. 151) ; the milra SCabra (fig- Fig. 149. Turrite'lla imbricata'ria. 152); the crassatella sulca'ta (Jig- 153); the car'dium porulo'sum Fig. 15QAmpulla'ria acuta. Fig. 151. Terr die' Hum fusifo'rme. Fig. 152.Mitra scabra. (Jig. 154). With these species are found a great many others, which have been described and figured in a great many books on the Fig. 153.Crassate'lla sulca'ta. environs of Paris ; there are species which are much more com- Fig. 154. Car'dium porulo'sum. 82 PARIS BASIN ANOPLOTHERIUM. mon than those named, but some of them are not found every- where, and others are seen first in the superior formations. 11. Above the marine limestone, or rather parallel with it, we find what is named fresh-water or silicious limestone, so called be- cause there is mingled in it a considerable quantity of silex, some- times uniformly disseminated, and at others forming here and there more or less voluminous masses (fig. 155), which constitute the mill- Millstone. Fig. 155. Fresh-water limestone, with masses of millstone without shells. stone without shells, which is wrought into millstones. Fluviatile shells are found in the lower parts of this bed, such as lymnea and planorbis. 12. The next group in the general series of Paris basin rocks consists of white and green marls, with a considerable quantity of gypsum, the latter being chiefly developed in the centre of the basin. The upper parts both of the marine and fresh-water lime- stone alternate occasionally with marls ; but the latter form, on the whole, a distinct overlying group of fresh-water origin, and contain land and fluviatile shells, fragments of wood, and great numbers of the bones of fresh-water fishes, of crocodiles, and other reptiles, of birds, and even of quadrupeds, the latter being usually isolated and often entire. The gypsum beds having been extensively quarried for the manufacture of "plaster of Paris" (obtained by burning the gypsum), they have yielded a multitude of these mammalian remains, which formed the base of the great dis- coveries of Cuvier so that the investigation of them by that anatomist may even be considered to have laid the foundation of the science of Paleontology, so far as it is dependent on sound principles of analogy. It is chiefly in the lower parts of the gypsum that these extinct quadrupeds are found. Such, for ex- ample, are the anoplo- the'rium and palco- thefriwn, pachyder- matous animals, more or less approaching to the rhinoceros and ta- pir, of which there were several species. The common anoplo- Fig. 156. Skeleton of the Anoploihe'rium commune, the'rium (fig. 156 11. What is the position of the fresh- water limestone of the Paris basin ? 12. What is found next above the limestones of the Paris basins ? What is plaster of Paris ? What fossils are found in the gypsum ? What is the Anoplothe'rium ? PALEOTHERIUM. MIOCENE. 83 from the Greek, a, without, oplon, arm, and therioh, animal), was of the size of an ass, of a heavy form, and with thick short legs and a long tail ; some species had slender legs, and must have been swift and active ; and others of the size of a hare, and even of a guinea-pig, which were nevertheless adult. 13. The paleothe' rium (fig. 157 from the Greek, palaios, ancient, and therion, a beast), was of the size of a horse, and form of a tapir ; species of various size, both large and small, existed. Fig. 157. Skeleton of the Paleothe'rium magnum. 14. Above the gypsum we find another more modern group, consisting of two formations, one marine and the other fresh- water. They are composed of marls, mica'ceous and quartzose sands, and layers of flint. These beds of sand are often of great thickness, and are at first coloured by oxide of iron, and then white and pure: they frequently form masses of sandstone, sometimes without or- ganic remains, or only rolled shells of the marine limestone ; some- times, on the contrary, they contain the casts or impressions of shells. On these sandstones repose new lacu'strine deposits, form- ing sometimes shell millstone, filled with lymnese (fig. 158), plano'rbis (fig. 159), and seeds ofchara, or gyro'gonites (jig. 160). Fig. 158. Lymnea longisca'ta. Fig. 159. Plano'rbis cuom'phalus. Fig.lGQ.Chara medi- cage'nula ? (greatly magnified.) 15. The Miocene, or middle tertiary period. During- this second part of the tertiary period both terrestrial and aquatic ani- 13. What is the Paleothe'rium ? 14. What lies above the gypsum ? 84 MIOCENE, OR MIDDLE TERTIARY. mals became more numerous, and more like those of our own times ; then there existed a great number of mollusks, belonging to species which still inhabit the seas of the present epoch. 16. In England the miocene tertiary is represented by a thin and variable heap of gravelly strata, called the " crag formation," which is divided into three parts. The lowest is called coralline crag, because a great many coral remains are found in it ; the next is the red crag, distinguished by its deep ferru'ginous stain ; the uppermost is named Norwich, or mammali'ferous crag, which is of more recent origin than the red crag, and contains bones of large mammals, and occasionally fresh-water shells. 17. An extensive series of miocene beds occupies the whole surface of both shores of the Chesapeake Bay, a hundred miles north and south, and fifty miles wide. A similar series occurs in Virginia. The lowest beds of the Chesapeake series are argilla'- ceous, and the uppermost are sandy ; both series abound in fossils, and when met on the side of a river they are sometimes found to consist of little else than shells and the remains of zo'ophytes, often in a high state of preservation. 18. The miocene tertiaries prevail extensively on the continent of Europe ia, various river basins. They occupy a considerable portion of the west of France, filling up the basins of the Loire and Garonne ; they fill up also a great part of the valley of the middle Rhine, and the whole of the great valley of Switzerland, between the. Alps and the Jura chain ; and from Switzerland they extend towards the north-east, following the course and partly fill- ing up the valley of the Danube. From point to point they may here be traced spreading out into extensive series near Vienna, and in Styria, and occurring again in the plains of Hungary ; they are also found in Poland and Russia ; they appear both in northern and southern Italy, and on the shores and islands of the Mediterra- nean. 19. The miocene beds of the basin of the Loire are chiefly de- veloped near the city of Tours, and in the Touraine district, where they consist for the most part of broken shells ; these beds, how- ever, sometimes afford a building stone, the comminuted shells being mixed with sand and gravel, and cemented by calcareous matter. In Switzerland there is a series of tertiary sandstones of the miocene period ; and between the lakes of Geneva and Lu- 15. What is remarked of the miocene period, as respects animals ? 16. How are the miocene beds represented in England ? What is coral- line crag ? What is red crag ? What is Norwich crag ? 1 7. In what part of the United States do we find examples of miocene beds? 18. Where do we find miocene beds in Europe ? 19. What is the nature of the miocene beds in Switzerland ? What is molasse ? MIOCENE FOSSILS. 85 cerne these beds consist of a coarse conglomerate, called " nagel- fluhe," passing into a finer sandstone (the "molasse" of French geologists), which is usually soft and incoherent, but sometimes sufficiently hard to be used as a building stone. Various beds of lignite and marl are irregularly distributed through the molasse, which are evidently of fresh-water origin. 20. The marine deposits of the miocene strata, although abound- ing in shells, do not contain as great a number of species as the marine limestone of the Paris basin; yet, eighteen per cent, of these species are identical with those now Jiving in the neighbour- ing seas. There is often the strongest analogy between these new deposits and the lower limestones, with which they have been confounded ; yet, if we do frequently observe a common aspect, and often find the same shells in both, there is, nevertheless, es- sential differences between them. In one case, we no longer find species characteristic of the lower deposits ; there is no ceri'thium giga'nteum, no car'dium porulo'sum, &c. : in the other, we find new remains which we did not meet with before, such as the Bala'nus cra'sus (Jig. 161), the Rostella'riapespelica'ni (Jig. 162), the Pe'cten pleurone'ctes (Jig. 163), &c., which are never found in the Paris basin, but exist in the subapennine formation. Fig. 161. Bala'- Fig. 162. Rostella'ria Fig. 163. Pe'cten mis crasus. pespelica'ni. pleurone'ctes. 21. The strata belonging to this period of the tertiary formation contain divers species of paleothe'rium, but differing from those found in the Paris gypsum. Here we also find several other species of animals, which constitute genera, no trace of which is met with in the preceding formation, and which totally disappear in the suc- ceeding epoch. Here we find the remains of mastodons (from the Greek, mastos, a nipple, and odous, tooth), animals analogous 20. What is the character of the fossils of these beds ? What proportion of them resemble recent or living 1 species? 8 86 MASTODON. DINOTHERIUM. to the elephant, but whose teeth (Jig. 164) have crowns studded with conical or nipple-like points, instead of being flat. On the miocene beds we also find the gigantic Dinotherium (from the Greek, dinos, circular, and therion, a beast), an animal resembling the tapir, which is remarkable by having the tusks turned downwards (fig- 165). It was first found in Hesse, afterwards Fig. 164. Tooth of a ma' sto- near Auch by M. Lartet, who sub- don (reduced). sequently found in the same place the bones of monkeys. Remains of the rhi- noceros, of the hippo- po'tamus, and of the castor are also found in these deposits. "The Dinothe'rium is the largest of the terres- trial mammalia of whose existence we have any positive knowledge, but as it is not a matter of absolute certainty at pre- sent of what nature its ex- tremities may have been, we are hardly in a condition to speak very decidedly of its general appearance or habits. It is chiefly known by the' fragments of the head and teeth, which exhibit a near approach, the former to the ceta'cean tribe, and the latter to the tapir ; but there is a remarkable and very striking anomaly in the existence of two large and heavy tusks placed at the extremity of the lower jaw, and curved downwards like the tusks in the upper jaw of the walrus. It is probable, from the size and position of these tusks, as well as from the structure of the bones of the head, that the animal was aquatic in its habits, living almost entirely in the water, and feeding on such succu- lent plants as it could there obtain. " The length of the Dinothe'rium is calculated to have been at least as much as eighteen feet, and its proportions were, probably, very much the same as those of the great American tapir. It was provided with a trunk, which seems to have been short, but extremely large and powerful, and capable of being employed to tear up the food which the tusks, acting' like pick-axes, may have loosened." Ansted. 22. The miocene is very rich in combustible material ; to it belong the lignites of Languedoc, of Provence, Switzerland, and most of those of Germany as well as the masses of earthy com- Fig. 1 65. Lower jaw and tusJc of the Dinothe'rium giga'nteum. 21. What fossil animal remains are found in these beds ? What is the Dinothe'rium ? LIGNITES. MOLASSE. 87 bustible in the neighbourhood of Cologne. All these Hgnites appear to have been formed chiefly from con'ifers, the structure of which (fig. 166) may be recognised in the mass of combustible itself, or in the wood disseminated through various deposits. C. Fig. 166. Structure of the wood of con'ifers. fl. Part of a transverse section of natural size. b. Part of the same section seen under a microscope. c. Longitudinal section, in the direction from B to C, also magnified. d. Section in the direction from A to B. 23. But the tertiary sandstones of the miocene period (the mo- lasse) also contain a great quantity of dicotyledonous plants, the wood of which is here and there found disseminated, sometimes in a silicious state, and clearly exhibiting the proper tissue or struc- ture of this class of plants (fig. 167), particularly characterized by the presence of large lono-i'tudinal vessels. We also find leaves, C. a. B. b. Fig. 167. Structure of the wood of dicoty'ledons. a. Part of a transverse section of natural size. b. Part of the same section, seen under the microscope, showing the large vessels. c. Longitudinal section in the direction from A to B, showing the struc- ture of the medullary rays, and that of a large vessel. 22. What is lignite ? From what family of plants were these lignites probably formed ? How is this family of plants recognised ? 23. What description of plants exist in the tertiary sandstone of the miocene period ? FOSSILS. Fig. lG8.Leafofanun determined elm. the midst of deposits of often in great numbers, in the clays which ac- company the lignites, in the characters of which we distinctly re- cognise existing dicoty'- ledons, such as walnuts, maples, elms, birches, fec. (Jig*. 168, 109). Even fruits are found which re distinguish- ed, often with difficulty, from those now grow- ing. 24. We also find in {h[s f ormatiori5 eilher fo Fig. 169. Complonia combustible -- a'cutilo'ba. ^ j n those O f Liblar near Cologne, or in the ar- gilla'ceous or sandy matter of the formation, the remains of monoco- ty'ledonous plants : there is wood presenting the structure of the palms, that is, an assemblage of woody fasciculi (bundles), longi- tudinally arranged, without regard Fi to regularity, in the middle of eel- 170. Structure of the icood Fig. 171. Palmacites Lamanonis. lular tissue, as seen (fg. 170). Leaves like the representation (fig. 171) are also met with. We find, too, in the miocene gypsum of the same na- ture as that of the Paris basin, which has led to the supposition that they were of the same epoch ; but besides this section of country being formed of the "molasse," the or- ganic remains are not of the same species. Towards the close of the miocene, or second epoch of 24. How do we recognise the previous existence of iiioiiocoty'ledonous plants from their fossil remains ? PLIOCENE. 89 the tertiary period, a new upheaval appears to have taken place in the region of the Alps. A part of this complicated chain of mountains had then long existed. Thus the Alps of Provence and of Dauphiny, which belong to a system of which Mont-Viso is the most remarkable point, date from the interval elapsed between the deposit of the inferior and upper lay- ers of the creta'ceous system ; other portions of the Alpine region were raised up at the same time as the Pyrenees, that is, after the creta'ceous period ; for example, the neighbourhood of Castel-Gomberts, and in the mountains which connect the Alps to the Jura, we perceive traces of an upheaval contemporaneous with that of Corsica, which occurred after the deposit of the eocene, or first period of the tertiary formation ; but the greater part of this majestic barrier between Italy and the north seems to have acquired its present configuration, and to have attained the immense height we now observe, in more recent times. The chain of the western Alps appears to have been upheaved after the deposit of the miocene or second series of the tertiary ; and the chain extending from Valais towards Austria appears to be of still more recent origin. Dating from the geological convulsion which gave to the western Alps their existing prominence, and at different points produced the elevation of the " molasse," and other tertiary strata of the miocene period, as well as those of more ancient epochs, Europe presented a great continental sjfcce ; and during the period of tranquillity which followed this catastrophe, marine deposits did not take place except on the shores or in gulfs not far from the centre of this region, as in the subapennine hills, in some parts of Sicily, and on a portion of the coast of England ; but sedimentary deposits occurred in the basins or valleys of still existing rivers, and in some lakes of fresh water which a more recent geological revolution has caused to disappear. 25. The Pliocene, or newer tertiary. In Europe the pliocene is chiefly represented in south Italy, in the Morea, and in the isl- ands of the eastern archipelago ; and important contemporaneous beds exist in the valley of the lower Rhine, near Bonn, and a por- tion of central France, as well as in southern Russia. 26. The pliocene beds are not all, however, of the same age, and the beds so called must have been in the course of formation for a very long period. Those of Italy admit of being subdivided into two groups, the older of which is called the sub-apennine, and attains a great thickness near Parma, exhibiting a considerable number and variety of fossils. These beds consist for the most part of greyish, brown, or blue marls, containing calcareous mat- ter, and overlaid by thick sandy beds. The Sicilian beds are dis- tinctly newer than these, and are equally extensive. Marls, with occasional limestone, form the great mass of the materials of these strata. Like the subapennines they are richly fossili'ferous, but are chiefly characterized by their shells. A fresh-water bed of the newer period is found at (Eningen, on the lake of Constance, and contains numerous remains of fishes, and some fragments of land animals. 27. From the eocene, or deposits of the Paris basin, there is a 25. In what parts of Europe are the pliocene beds represented ? 26. Are all pliocene beds of the same age? What is the character of the Sicilian beds ? 8* 90 FOSSILS. progressive increase in the number or proportion of recent species found : in the Paris basin three per cent, of the fossil shells are analogous to the shells now .existing ; in the miocene, eighteen per cent., and in the pliocene fifty per cent, of the fossil shells resem- ble existing species. There is scarcely any analogy between the shells of the Paris basin limestone and those of the subapennine hills. Besides the Balanus crasus (Jig. 161), and the Rostella'- ria pespelica'ni (Jig. 162), we may cite the Pleuro'toma rota'ta (fig. 172), the Buc'cinum prisma'ticum (fig. 173), the Volu'ta Lambe'rti (fig. 174), &c., and almost all the shells 01 the Mediter- ranean. Fig. 172. Pleura' toma Fig. 173. Buc'cinum rota'ta. prisma'ticum. Fig. n4Vplu'la Lambe'rti. Fig. I15.Murex alveola'tus. Fig. 176. Astarte Bas- teroli. Fig. m.Cy'prea coccinelloides. The deposits alluded to also contain masses of lignites, which arc advan- tageously worked in different localities. Some offer regular layers of a sort of compact coal (brown coal), accompanied by fresh- water shells, indicating a tranquil deposit in lakes ; but the greatest number contain only irregular masses of wood, some of which present the texture of the con'ifers. A great number of leaves, analogous to those of existing dicoty'ledons, are also found. 27. What proportion of fossils found in the eocene, miocene, and plio- cene respectively, resemble species now living ? BONE CAVERNS. 91 28. The pliocene beds of the United States seem to belong chiefly to a very modern period ; they exist to a great extent in several localities. At the mouth of the Potomac, in Maryland, is a series of clay beds, alternating occasionally with sand. All the fossils found in these beds are identical with those species found living on the neighbouring sea-coast, a positive indication of the newness of these beds. Similar beds exist at Niagara and in Kentucky, and in other parts of North America ; in all cases the recent deposits are very striking. 29. While these lacu'strine deposits were tranquilly forming be- neath the waters, the then uncovered surface of the earth was in- habited by hyenas, cavern bears, hairy elephants, ma'stodons, rhi- noceroses, hippopo'tami and other animals belonging to genera still in existence, but the species of which are now lost ; they appear to have been destroyed in the geological revolution which raised up the principal chain of the Alps, and gave to these mountains their present configuration, and its present shape to the European continent. It is probable, too, that the same revolution destroyed the multitude of animals whose bones are found at the bottom of certain caverns or fissures in the rocks, where they are buried in a sort of calcareous cement, ordinarily of a reddish colour. 30. BONE CAVERNS. The most ancient caverns, celebrated for the remains of mammals which they contain, are those of Harz and of Franconia ; but since Dr. Buckland has shown the pro- priety of removing the mud, sands, rolled flints-, stala'gmites, &c., which often cover the bone collections, these remains have been found everywhere, even in places where they had not been pre- viously supposed to exist. 31. Most of these caverns appear to have had one or more lateral openings, affording easy entrance to the animals that fre- quented them, as places of refuge, to devour their prey, and finally they came to them to die. Here their bones accumulated through a great many generations, and we now find them buried in a dark earth, in or on which we recognise their dejections. Often we find among the bones of a certain genus of animals other bones, having upon them the print of teeth, showing they had been the prey of the first. The greater number of these bones belong to the bear tribe, two species of which were larger than any now existing ; or to the hyena tribe, also larger than those now known. Sometimes one, and sometimes the other of these genera predomi- nates ; a species of wolf abounds in the bear caverns of Galenreuth in Franconia : other carni'vora, of the genus dog, and those of the genus cat, including species of cougars, are everywhere in small 28. In what parts of the United States do pliocene beds exist? 29. What kind of animals inhabited the land while theje-Ja&tt^gtcine de- posits were being formed ? 30. What are bone caverns ? Jf r HE 31. What are the features of bone caverns? ' 81 Kj I y p D Q |TY 92 SUPERFICIAL DEPOSITS. numbers. The remains of rodents, of ruminants, also of large pachyderms and of birds, which have been dragged as prey to these resorts, are also found. SUPERFICIAL DEPOSITS. " The regularly stratified deposits, of whatever geological period they may be, are in most parts of the world covered up, more or less, by a con- siderable mass of heterogeneous material derived from the degradation of the more ancient rocks. This mass is generally unstratified, and deposited in irregular heaps, partially filling up valleys, covering low tracts of level country, and sometimes even capping low hills, but almost always bearing marks of having been transported from a distance over ranges of high land, although not without some reference to the present physical features of the country over which it has travelled. "Occasionally the fragments which have been thus conveyed are of large size and angular, and in this case they are called "boulders," or "erratic blocks ;" but such masses have not generally travelled to any very con- siderable distance from the parent rock. The transported fragments are much more commonly of small size, and rounded, as if by mutual attrition, at the bottom of the sea ; and in this state they have been often carried to very great distances, and are found many hundred miles from the place whence they seem to have been derived. They are then called ' gravel,' and are riot unfrequently mingled with bones and fragments of bones of large quadrupeds." Ansted. 32. These superficial deposits are termed DRIFT, and comprise deposits of water-worn, transported materials, consisting of gravel, boulders, sand, clay, &c. 33. Drift is divided into DILU'VIUM, or ancient drift, and ALLU'- VIUM (from the Latin, alluo, I wash upon), or modern drift. 34. The DILU'VIUM (formed from the Latin, diluo, I wash away) co- vers up the tertiary depo- sits, and contains fossils whose origin dates back to a period not very long antecedent to the present. In fact the dilu'vium, to a certain extent, unites the tertiary with the re- cent period. It contains the bones of large mam- mals, both of extinct and recent genera and spe- cies. Among them we may perhaps place the enormous megathe'rium Fig. 178. Skeleton of the Megatherium. (fig- 178 from the 32. What is meant by drift ? 33. How is drift divided ? What is the difference between dilu'vium and allu'vium ? MEGATHERIUM BOULDER FORMATION. 93 Greek, mcgas, great, and therion, beast), which was not less than eighteen feet long and nine feet high. The skeleton is analogous to that of animals of the order edentata. The thigh-bone in the megathe'rium is nearly three times as great as the largest known elephant ; the bones of the instep and those of the foot are of cor- responding size, the heel-bone projects back nearly eighteen inches, and the small bones of the foot advanced as much forwards. The third toe is provided with a socket to receive a claw, the sheath of which measures thirteen inches in circumference, and the core on which the nail was attached is ten inches in length. The fore limbs were well adapted for grasping the trunk or larger branches of a tree. This animal was slow in its movements, and probably fed on roots, which its teeth were admirably adapted for grinding. 35. To the diluvial drift are also referred the great collections of bones of the Icy ocean, on the coasts of Siberia and on the neighbouring islands : there a number of enormous animals, their flesh preserved through thousands of years, lie buried in sands consolidated by perpetual ice ; in the same situations have been found stags and horses, the elephant and rhinoceros, covered with hair, seemingly indicating that the species which then lived in northern climates were enabled to bear, from being clothed in fur, lower temperatures than those with naked skins which now inhabit southern Asia and Africa. The tusks of these elephants of the ancient world are sought for the ivory they afford, and compete, in commerce, with those of modern elephants. It is perhaps to the dilu'vium we must refer those immense masses of rolled debris which contain gold, platina, and the diamond, in Brazil, in Africa, in India, and in the Oural mountains, as well as the arena'ceous veins of tin in Cornwall arid Mexico. 36. The BOULDER 'FORMATION, or ERRATIC BLOCK FORMATION, also, is regarded as a part of the diluvial drift. A great part of the plain of Switzerland is covered at intervals by fragments of rock, measuring about a cubic yard, which strew the plain, and dot the sides of the Alpine ravines, and rise on the opposite side of the Jura range, even to an elevation of several thousand feet above the sea. The most concentrated distribution of these blocks seems to be near the town of Neuchatel, but similar masses are also found on the summit of the Mont Saleve, behind Geneva. It is very remarkable that a belt of fragmentary masses (not few or small, but countless and gigantic), differing entirely in character from the formation on which they rest, should be found lying on a steep, almost precipitous slope of nearly bare or thinly -covered rock. One of the blocks behind Neuchatel, eight hundred and fifty feet above the lake, is of granite, and measures between fifty 34. What is the position of diluvial drift ? What is the megathe'rium ? 35. What other fossils are referred to the diluvial drift ? 36. What is the nature of the Boulder formation ? 94 ALLUVIUM, OR MODERN DRIFT. and sixty feet in length, by twenty feet broad, and forty feet high, while between the Jura and the Alps blocks still larger are in many places to be found one, out of a great number together in the canton of Berne, measuring 01,000 cubic feet. 37. Erratic blocks and gravel cover the plain of central Europe and the steppes of Russia. Almost the whole surface of North America, as far as it has been examined, has been found covered with gravel, pebbles, and boulders, varying greatly in thickness, and obviously of the same origin as similar deposits in Europe ; and a region which has been called the great Atlantic plain, ex- tending between the Alleghany mountains and the Atlantic ocean, together with the lower part of the great valley of the Missisippi, appear to* be the districts where it conceals the underlying deposits to the greatest depth. On the borders of Lakes Erie and Ontario there are very de- cided marks of the great drift which has elsewhere overspread North America, and the boulder formation, containing marine shells, extends into the valley of the St. Lawrence, as far down as Quebec, and at a height of at least three hundred feet above the sea-level. Below Gluebec there are large and far-transported boul- ders in beds, both above and below these marine shells, and wherever the contact of the drift with hard subjacent rocks is seen, these rocks are smoothed and furrowed on the surface, as they are in similar positions in northern Europe. 38. ALLU'VIUM, or MODERN DRIFT. In many parts of North America the valleys are filled up to a depth of twenty or thirty feet with unconsolidated beds of earth of various kinds, and the heteroge'neous mass contains in it abundant remains of large pachyde'rmatous animals, not now living in the country, but asso- ciated with, and overlaid by other and similar beds, in which occur the bones of buffaloes, that have within a fe\v years been driven westward by the advancing steps of civilized man. These beds all belong to the same geological period, or nearly so, and a descrip- tion of one will be sufficient to give an accurate notion of a multi- tude of similar bogs and soft meadows in many of the western states. The most remarkable is that known as the " Big Bone Lick" in Kentucky. 39. The Big Bone Lick occupies the bottom of a boggy valley, kept wet by a number of salt springs, which rise over a surface of several acres, and the substratum of the country is a fossili'ferous limestone. At the Lick the valley is filled up to the depth of not less .than thirty feet with beds of earth, the uppermost of which is a yellow clay, apparently the soil brought down from the high grounds by rains and land floods. In this yellow earth, along the 37. Where is the Boulder formation met with ? 38. What is allu'vium ? 39. What are the characters of the Big Bone Lick of Kentucky ? EIGHTH GEOLOGICAL EPOCH. 95 water-courses at various depths, the bones of buffaloes and other modern animals are often found quite entire. Beneath the clay is another layer of a different soil, bearing the appearance of having been formerly the bottom of a marsh. It is more gravelly, darker coloured, and softer than the other, and in it, or sometimes in a stratum of compact blue clay alternating with it, there are found innumerable bones of large mammals, chiefly ma'stodons, but in- cluding also elephants, and extinct species of animals of the ox and deer tribe. In other localities the ma'stodon bones are found immediately below the surface in reclaimed marshes, and they are sometimes extremely perfect, sometimes broken and water-worn. The Big Bone Lick would appear to have been resorted to, not only in modern times by the living races, but more anciently by animals now extinct, for the salt, and perhaps the food produced by the marsh. The buffalo and bison are frequently known to perish entrapped in these licks and swamps, and it seems evident that the ma'stodon and elephant of former times must, from their huge size and unwieldy forms, have been at least equally exposed to the same fate. Jlnsted, Rogers, fyc. 40. Up to the present time all geologists agree in saying that in the formations of this period, as well as in the most ancient rocks, neither human bones nor any vestige indicative of the existence of man on the face of the earth has been found, and it is, for this rea- son, probable that man had not yet been created at the time of the destruction of these animals. EIGHTH GEOLOGICAL EPOCH. Modern Formation. 41. New formations are now being made, either by the effusion of igneous matter from the bowels of the earth, or by sediment from waters, and these formations, which are contemporaneous with man, constitute the modern formation. 42. Since the last great catastrophe alluded to (the upheaval of the Alps), there has been a general repose, which perhaps will be disturbed one day by some new geological revolution ; by the up- heaval of some great mountain chain, for example, and by the great rush of waters which must follow such a convulsion, new lands will rise from the bosom of the ocean, and probably enclose remains of the bony frame of man and of animals now existing, just as the ancient formations conceal the solid remains of creatures which preceded us on the earth. Even now we have proof that things must pass in the present time very nearly as they did in 40. Are human bones found in a fossil state, in the formations thus far studied ? What is the inference from the fact ? 41. What is meant by modern formation? 42. Are human bones any where found in a fossil state ? 96 MODERN FORMATION. ages long gone by-, for in certain modern formations, which con- tinue to be formed under our eyes, we find human skeletons im- bedded in the substance of the rock, and already presenting the characters of fossils of the tertiary period. One of the most re- markable examples of this kind has been discovered in the island of Guadaloupe. Thus far we have presented a sketch of the earth's structure as revealed to us by an examination of its crust, only in reference, however, to the order of superposition of its formations, resulting from great geological convulsions, and characterized by the remains of animals found entombed in it. When we reflect on the incon- ceivable length of time it has evidently required to effect all these changes, and elevate one above another gigantic stories of various rocks, the imagination is startled ; when we see entire creations of plants and animals covering the surface of the earth, and inhabit- ing the waters, disappear after a time, leaving a few mutilated re- mains as the only trace of their existence, and give place to a new flora and a new population of animated creatures, destined to un- dergo in turn a similar fate, we are struck with astonishment, and overcome by admiration of the power of the Creator 'of things so grand and so beautiful. LESSON VI. INFLUENCE OF INTERNAL AGENTS ON THE SURFACE OF THE EARTH. EARTHQUAKES Description Effects of Changes of level pro- duced by Upheaval and Subsidence Constant level of seas Slow and progressive Subsidence General conclusions. VOLCANIC PHENOMENA. Explosion Eruption Island of Saint George Monte-Nuovo Jorullo Vesuvius Definition of a Volcano Submarine Eruptions Volcan of Unalaska Crater of elevation Formation of Craters Effects of upheaval Form of Volcanic Islands Periods in the formation of a Volcano Interior of Craters Kirauea Solfataras Volcanic fishes Lava Currents Characters of Lavas Dykes Gas- eous Volcanic Products Eruption of Mud Solid products of Volcanoes Trachyte Obsidian Compact Lavas Po- rous Lavas, $c. 1. We have spoken of formations and of their relative order of superposition, and occasionally alluded to the various causes which affect them. From what we have said it might be inferred that the several formations are so many concentric spheres, enveloping 1. Why is it that the surface of the globe is not entirely smooth, free from mountains and valleys ? DESCRIPTION OF EARTHQUAKES. 97 a mass of fire ; and such in fact might have been the case had it not been for certain disturbing forces which have fashioned the mountains and valleys, and caused the dry land to be lifted up above the waters. Had it not been for these disturbing forces, phenomena analogous to volcanoes and earthquakes, the whole globe would have remained under water, and man would not have been called into existence. But having seen the general structure of the interior of the earth, we will study the phenomena, the dis- turbing forces which modify its surface, more particularly than we have yet done. These disturbing forces are either internal or external ; first, of the INFLUENCE OF INTERNAL AGENTS ON THE SURFACE OF THE EARTH. It has been already stated (page 12) that the centre of our earth is a mass of fire, to the influence of which many phenomena may be referred. EARTHQUAKES. 2. Description of Earthquakes. Every one has heard of the terrible scourge which in a moment reduces the most flourishing cities to a heap of ruins, and sometimes upturns the neighbouring country. An earthquake is often preceded by rumbling, subterra- neous sounds, which are frequently heard some time before the catastrophe. Tremblings more or less violent are perceived during a few minutes or seconds only, which in many instances are often repeated with more or less rapidity and force ; in certain cases they even continue, with irregular intervals, during several days, or months, or even entire years. These movements of the earth are of different kinds ; sometimes they consist of jerking horizon- tal oscillations, occurring at irregular intervals, sometimes of verti- cal shocks, that is, in rapid and successive rising and falling of the soil ; at other times of various twisting movements. Frequently all the various motions take place almost at the same moment, and then nothing can escape destruction. 3. Sometimes an earthquake is circumscribed in narrow limits ; that which happened on the 2d of February, 1828, in the island of Ischia, was not felt either in the neighbouring islands or on the continent. Frequently, too, it shakes an immense surface : for example, the earthquake of the 17th June, 1826, in New Grenada, was felt over many thousand square leagues. Sometimes it extends enormous distances, as in the case of the famous earthquake of Lisbon, which was felt in Lapland in one direction, and Martinique in another ; and, transversely, from Greenland to Africa, where 2. What are earthquakes ? What is the nature of the motions produced by earthquakes ? What is the duration of earthquakes ? 3. What are the limits of earthquakes ? 9 EFFECTS OF EARTHQUAKES. Morocco, Fez, and Mequinez were destroyed : ail Europe expe- rienced its effects at the same moment. From the different histo- ries of earthquakes, many examples of this kind of propagation might be adduced, extending more or less widely. It may beeren concluded, from statements of facts, that the shock extends accord- ing to a great circle, more or less inclined to the equator, and per- haps over an entire hemisphere. 4. Effects of Earthquakes. Earthquakes, when violent, not only overturn entire cities, and the most solidly built edifices, but they cause important modifications" in the ground itself. Those of Calabria, in 1783, furnish examples, which are the more important because the facts were observed by the most distinguished men of the times, such as Vicenzio, physician to the king of Naples, Gri- maldi, Hamilton, Dolomieu, &c., and also by a commission ap- pointed by the royal academy of Naples. All was overturned in this unhappy country ; the course of rivers was interrupted and changed ; houses were raised above the level of the country, while others, frequently at no great distance, were sunk down more or less ; edifices of great solidity were split from top to bottom ; cer- tain parts were raised above others, and the foundations pushed up out of the ground. Every where the surface of the earth partly opened, often in long crevices, some of which were one hundred and fifty yards in breadth ; some of these were isolated, sometimes bifurcated frequently exhibiting other fissures perpendicular to their direction (Jig. 179); some were in form of rays diverging from a centre, like a broken glass (fig. 180). Some opened at^ne Fig. 179. Fig. 180. Crevasses and fissures produced by earthquakes. moment of the shock, and immediately closed again, grinding be- twixt their parietes the habitations they swallowed up ; others in- variably remained gaping after the commotion, or, commenced by a first shock, were widened by succeeding shocks. In both cases it was sometimes observed that the borders of the split were on the same plane, or showed a more or less projecting swelling up 4. What are the effects of earthquakes? What is the character of fis- sures produced by earthquakes ? UPHEAVAL AND SUBSIDENCE. 99 Q\ 181); sometimes one of the parts is elevated much higher than the other (Jigs. 182, 183), showing that one must have been raised while the other was sunk. Fig. 181. Fig. 182. Fig. 183. Changes of level produced by earthquakes. Again it happens that a more or less considerable extent of surface is suddenly sunk, carrying down plantations and habitations, leaving yawning chasms, with vertical sides, eighty or a hundred yards in depth. In certain cases an immense quantity of water springs from the bottom of these cavi- ties, forming more or less extensive lakes, sometimes without apparent cur- rent, and sometimes giving origin to impetuous torrents. In some instances, on the contrary, rivulets were absorbed by the fissures in the earth, or swal- lowed for a time, or forever. But, besides the numerous cracks and divers chasms which intercept the waters, furnishing new springs, and giving them a new channel, it also happens that masses of rocks, falling across valleys, arrest the waters and soon form lakes in the upper part. Now, these accumulated waters make new passages, either by breaking through the sides of the valley, or by en- larging some fissure in the mountain ; or, they degrade, cut down, the obsta- cle which retained them, and soon overturn it entirely or in part Hence arise those fearful outbreaks, those impetuous torrents rolling down enor- mous masses of rock, the ravages of which are as disastrous as the earth- quake itself, and which, excavating new channels, or widening and deep- ening those that waters before pursued, mark their course by the debris which they roll down and successively deposit. When the principal effects of earthquakes took place on the continent between Oppido and Soriano, the phenomena extended as far as Messina, across the straits ; more than half the city was destroyed, and twenty-nine hamlets or villages were swallowed up. The bottom of the sea was sunk, and disturbed at various points ; the shore was rent, and the whole ground along the port of Messina was inclined towards the sea, suddenly sinking several yards ; the whole promontory which formed its entrance was swal- lowed in a moment. 5. Upheaval and Subsidence. The earthquakes which occurred on the coast of Chile in 1822, 1835, and 1837, have produced effects not less remarkable. Different parts of the coast, from Valdivia to Valparaiso, that is, an extent of more than two hundred leagues, were evidently elevated above the waters, as well as many neighbouring islands as far as those of Juan Fernandez ; the bot- tom of the sea to a considerable extent participated in this phe- nomena. On the coast, rocks which had been previously under water were raised two or three yards above its level, with the mol- 5. Give some examples of upheaval and subsidence produced by earth- quakes. 100 UPHEAVAL AND SUBSIDENCE. lusks which lived on their surface ; rivers emptying on the coast became fordable where they had been navigable by small vessels ; well-known anchorages were diminished in depth to a correspond- ing extent, and at different points, shoals now oppose the passage of vessels of large draught where they readily floated before. Analogous circumstances occurred in India in 1819; a hill, fifty miles long and sixteen broad, was raised up in the midst of a flat country, barring the course of the Indus. Further to the south, on the contrary, but parallel to the same direction, the country sank, carrying down the village and fort of Sindre, which nevertheless remains standing, half submerged. The eastern mouth of the river became more shallow in many places, and por- tions of its bed which had been fordable suddenly ceased to be so. The history of all times and of all places furnishes us with facts of exactly the same nature. Everywhere we are told of fissures in the earth, of pro- found chasms, in which cities and even entire countries are swallowed, from which flow mephitic gases, enormous masses of water, sometimes cold, sometimes hot, sometimes even flaming. Also of plains suddenly trans- formed into mountains, of shoals raised in the midst of the ocean, of moun- tains rent and overturned, of mountainous regions, of hundreds of leagues of rocks all at once levelled and replaced by lakes. Of water-courses changed, swallowed in chasms of the earth ; of lakes which dry up by breaking through their bounds, or suddenly lost in subterraneous conduits, instantaneously formed. In opposition, we also learn of enormous springs producing new streams, suddenly rising through a fissure of a rock, without any knowledge whence the waters come : of thermal springs which have become instantaneously cold ; of others, on the contrary, appearing where they did not exist before. All these phenomena are so many indications of fissures in the earth, which afford new channels to waters which might have circulated there before. 6. Relatively to the sea-coasts, these phenomena are often men- tioned by authors in a peculiar manner ; rarely do we see it expli- citly announced, there is an elevation ; but the event is stated in other terms, referring the effect to the most moveable element. In this way authors speak of the sea having retired more or less, leav- ing its bed dry, either permanently or only for an instant : some- times, on the contrary, they mention that the sea suddenly over- flowed more or less elevated coasts. Geologists translate these indications by the term oscillation^ if the phenomenon be mo- mentary, and by the terms upheaval, or subsidence of coasts, if it be permanent, because they refer these effects to the solid parts of the globe, and not to the sea, the level of which does not vary. Nevertheless it must be borne in mind that, if these transitory phe- nomena may sometimes be attributed to oscillations of the earth, they may also arise from a real impulse communicated to the waters of the sea, and possibly partake of both causes. We know, in fact, that during earthquakes the sea is sometimes vio- lently agitated, that its waters, elevated to considerable heights, occasionally make fearful irruptions on the land, advancing and 6. What is meant by oscillation ? What is meant by upheaval ? What by subsidence ? CONSTANT LEVEL OF SEAS. 101 retiring again, carrying devastation over a greater or less extent. These impetuous movements of advance and retreat, accompanied by sudden dislocations caused by subterraneous commotions in the solid crust of the globe, may occasion frightful havoc. The his- tory of the Grecian archipelago, of the islands of Japan, and of a multitude of places, is full of disasters produced by these catas- trophes. The various effects produced by earthquakes under our eyes, and those cited in the most authentic narrations, tend to confirm what is transmitted to us from the most remote times, although we might state the facts in other terms. Who dares formally to contradict Pliny, relating, according to the historians, that Sicily was separated from Italy by an earthquake ; that the island Cy'prus was separated from Syria by the same means ; and that of Eubre'a (Negropont) from Bosotia, &c. ? We would not even positively deny the existence of the Atlantis, swallowed by the waters, according to Egyp- tian tradition, in a dav and a night. Let us rather declare, that the assem- blage of observations we have, evidently shows that immense upheavals and subsidences have for a long time formed part of the mechanism of nature, in bringing the surface of the earth to the configuration we -now observe. 7. Constant level of seas. We have just admitted the subsid- ence and upheaval of coasts, and laid down the principle that the level of seas is invariable : but this last assertion being contrary to opinions commonly received by the world, it is necessary to sup- port it by demonstration. The laws of hydrostatics teach us that a mass of liquid cannot be permanently elevated or depressed at one point of its surface, but that a level must be established after oscillation, great or small, ceases. Hence it follows that the level of the sea cannot be stationary at one point, without its being so throughout, and that the waters cannot be elevated or depressed in one spot, without similar changes being experienced at all points of the same basin. Now we know thousands of localities where the surface of the sea has not undergone the least variation since the most remote historic times ; therefore the level has not changed, and its constancy is the most positive fact we are aware of, be- cause it has been subject to the proof of all ages. On the other hand, if we could be led to suppose, like the inhabitants of Chile, seeing the manifest change on their coast, that the sea has sub- sided there, we must also conclude, with the inhabitants of Cali- fornia, Peru, Brazil, &c., that in those places it underwent no variation. It must also be admitted that the sea has risen at the bottom of the Gulf of Arabia, as it has done, in different epochs, on the coasts of Portugal, in the Straits of Messina, &c. All these circumstances are incompatible with each other, and opposed to the laws of hydrostatics ; and hence we conclude, that instead of the immutability of the ground, which an error, analogous to the idea of immobility of the globe, has created, we must admit immu- 7. Does the sea always maintain the same level ? What reasons lead to the opinion that the level of seas is always the same? 9* 102 SLOW AND PROGRESSIVE SUBSIDENCE. lability of the seas, by acknowledging that the solid surface of our planet is susceptible of elevations, depressions, and all kinds of disturbances. The slow upheaval of Sweden has already been noticed (p. 20). 8. Slow and progressive subsidence. There is no doubt that, for four centuries past, the western coast of Greenland is continu- ally sinking, through an extent of two hundred leagues north and south ; ancient buildings, both on the low islands and on the con- tinent, have been gradually submerged ; and it has been frequently necessary to move various establishments built near the shore, farther inland. Subsidence of certain islands in the South Seas has been indicated ; but in those places, so rarely visited by geologists, the facts are not yet clearly established. 9. General conclusion. It must now appear to be well estab- lished, that earthquakes are capable of producing great modifica- tions of the earth's surface, since, within our times, vast tracts of country have been elevated sensibly above the level of the sea. It is not less evident there is a slow power in operation, in virtue of which, different parts of our continents may also be successively raised ; and that it also produces gradual sinkings as well as sud- den subsidences, which are doubtless correlative phenomena. All these circumstances, however remarkable, are, nevertheless, not very astonishing, when we reflect on the enormous dispropor- tion which exists between the thickness of the solid crust of the globe, and the mass of melted matter it envelopes. Is it surprising that such a crust, a mere rind, relatively almost as thin as a coating of gold-leaf on an orange, should be disturbed in every manner by the least movement of the subjacent mass, particularly if we bear in mind that similar movements doubtlessly have been taking place ever since the first pellicle was consolidated on the surface, and all the successive crusts must have been rent in every direc- tion, and therefore their mass could not afford the resistance of a continuous envelope ? VOLCANIC PHENOMENA. 10. General notion Explosion Eruption. Volcanic pheno- mena are closely connected with earthquakes; they are, in a manner, the final results of them. When, by the shaking and ele- vation of the ground, the terrestrial crust is deeply broken, a tem- porary or permanent communication is established between the interior and exterior of the globe, through which various kinds of matter are disengaged from the bosom of the earth. Through the crevices escape gases of different kinds, waters hot or cold, simple 8. Is there any evidence of the slow and gradual subsidence of land ? 9. Why is it believed that earthquakes modify the earth's surface ? 10. What are volcanic phenomena? Give some instances of volcanic phenomena. VOLCANIC PHENOMENA. 103 or sulphurous, and loaded with mud, are the most simple transi- tory results. But frequently there are, also, through the upheaved and broken ground, amidst violent detonations, explosions which eject, to a great distance, all the debris of the formation, as happened at Saint-Michel, in the Azores, in 1522, where the debris of two hills covered the whole city of Villa-Franca. It most frequently happens, at the same time, that more or less con- siderable eruptions of incandescent matters take place, consisting of scoria?, pumice, &c., in a melted state, which are either projected to a distance, or run on the slopes, or accumulate on the spot to a greater or less height ; this has occurred in a great many localities. Eruption of the island of Saint George. In tho month of May 1808, in the island of Saint George, one of the Azores, the soil in the midst of culti- vated fields after being upheaved opened at many points with a fearful noise. It first formed a vast cavity, or crater, of 100,000 square yards, then a smaller one at the distance of a league, and finally twelve or fifteen little craters on the broken surface. An enormous quantity of scoriae and pumice was projected to a distance, and the ground was covered a yard and a half deep over an extent a league wide and four leagues long. For more than three weeks afterwards currents of melted matter flowed from the principal crater to the sea. Monte-Nuovo. Monte-Nuovo, formed in 1538, at the bottom of the bay of Baia, on the coast of Naples, is another example of a similar eruption. Violent earthquakes had continued during two years : on the 27th and 28th September they did not cease either day or night ; the plain found between Lake Averne, Montc-Barbaro and the sea, was then upheaved, and various cracks were evident, Sfc. (Pietro Giacomo di Toledo). Then a great extent of ground was elevated, and suddenly assumed the form of a growing moun- tain ; in the night of the same day this little mountain of earth opened with a great noise, and vomited flames, as well as pumice, stones and cinders (Porzio). The pumice came froifr the upheaval of the soil, which consists of this material throughout Campa'riia ; and the stones and cinders came from the eruption which occurred at the moment : we still see on the south side of the mountain a ridge of scoriae, and on its summit the crater which produced them. The eruption lasted seven days, and the matters projected and ejected partly filled Lake Lucrin. From that time the most perfect tranquillity has prevailed. Jorullo. There was something analogous, but under peculiar circum- stances, in what happened in Mechoacan, n 187). In all cases, the result is a centre of easy communication between the interior and exterior of the earth, and it is this which is called a volcan or vol- _ Q/S^^^fe cano. Fig.\81. Volcanic conduits. This facility of communication is probably a preservative against the vi'o- lence of earthquakes ; indeed it has been observed that, from the moment an eruption takes place anywhere, the shocks which had been felt up to that time, become fewer and weaker, and even cease altogether. The earthquake of Caraccas, in 1812, terminated by the eruption of the volean of Saint- Vincent, in the Antilles ; the eruption of Jorvllo, and that -of Montc-Nuevo, terminated the earthquakes which desolated the surrounding countries. On the contrary, when a volcano becomes inactive, it seems to announce earth- quakes ; in 1797, when the volcan of Purace, near Popayan, had ceased to emit flame and smoke, the valley of Quito was agitated by violent shocks. Volcans, therefore, seem to be natural vents, designed by Providence to pre- vent a complete destruction of the globe, and its inevitable rupture into frag- ments, which, launched into space, might there describe new orbits. 12. Submarine eruptions. It is not only on land that volcanic phenomena occur ; they also take place under the sea, as might be naturally anticipated. In our own times, we have had formed in this manner the island of Julia, in 1831, on the south-west of Sicily ; Bogoslaw, in 1814, in the Aleutian Archipelago ; Sabrina, and another one not named, in 1811, in the Azores, where, previously, at different epochs, others were formed, according to the most authentic histories. The same thing occurred, at different times, around Iceland : and various accounts indicate that in the islands of Sunda, the Philippines and Moluccas, throughout the Pacific, in the Kuriles, Kamtschatka, &c., similar phenomena took place. Volcan of Unalaska. One of the most striking examples is furnished by the island, which arose in 1796, about ten leagues from the northern point of Unalaska, one of the Aleutian islands. At first a column of smoke rose above the surface of the sea ; then a black point appeared, the smmit of which launched forth sheets of fire and stones with violence. This pheno- menon continued for several months, during which the island grew succes- sively in extent and height; later, srnoke only issued, which ceased altoge. ther four years afterwards. Still the island continued to enlarge, and to rise 12. Do volcanic eruptions take place on land exclusively ? 106 PHENOMENA OF SUBMARINE ERUPTIONS. without any apparent ejection ; and, in 1806, it formed a cone which might be seen from Unalaska, and upon it were four other smaller ones, on the north-west side. Santorin. The Mediterranean also furnishes a fine example of submarine eruptions, in the midst of the space comprised between the islands of San- torin, Teresia and Aspronisi (Jig. 193), which, according to the ancients, appeared above the water several centuries before the Christian era, in con- sequence of violent earthquakes. In this circuit, Hiera arose first, 186 years before our era, which subsequently grew by little islets rising on its borders in the years 19, 726, 1427 ; then, in the same way, Micra-Kamcni, in 1573, and Nea-Kameni, in 1707, were formed ; and successively growing in 1709, 1711, 1712, &,c. No crater was formed in either of these islands, and we only have there the appearance of volcanic matter in form of a dome, which seems to have covered the orifice through which it escaped.- There was no volcan there, according to the terms of our definition, but a tendency to form one at some future time. The islands of Milo, Argentiera, Polino, Polican- dro, Poros, &c., are formed of the same materials, and probably had the same origin. 13. Wlmt passes in these phenomena. These submarine phe- nomena are announced by incandescent matters ejected above water ; by scoria? and pumice, which float on the surface ; by burn- ing rocks, which appear in the midst of waves of vapour, and by the boiling of the sea, the temperature of which becomes very niuch increased. All these things occurred in our own times, at Julia, at Sabrina, &c., and are such as authors mention in detail, in all their accounts. Father Goree has given us a history of the upheaval of Nea-Kameni, of Santorin, in 1707 ; and all the cir- cumstances he relates agree with what Strabo, Pliny, Plutarch and Justin tell us of the appearance of Hiera, in the midst of flames, and a violent ebullition of the sea. But the circumstances we have just spoken of are not always all present at the same time. Sometimes no solid rock appears above water; this was the case at Kamtschatka, in 1737, where jets of vapour, great ebul- lition of the sea, and pumice-stones floating on the surface, were all that was perceived ; but when the spot could be approached, there was found a chaiu of submarine mountains, where there had been previously a depth of more than a hundred fathoms. In certain cases there is not even a jet of vapour, and the phenomenon is manifested by the heat of the water only ; this happened in 1820, at the island of Banda, among the Moluccas, where the bay, which was upwards of fifty fathoms deep, was filled by the tranquil elevation of compact basa'ltic matter, probably pre-existing, which formed an elevated promontory composed of large blocks piled one on the other ; and its appearance was manifested by the heat of the water only. It also seems, that after eruptions, there is often a peaceful and slow upheaval, as in the island formed before Unalaska, and at Santorin, according to the observations of M. Virlet. Indeed, between Micra-Kameni and the port of Phira, where there is an abrupt submarine mountain, there was, at the be- ginning of the present century, fifteen fathoms of water above the highest part ; but there were only four fathoms in 1830, and little more than two in 1834. It is presumed a new island, that is, the summit of a new cone, will appear in the gulf, and the appearance will, probably, be accompanied by such phenomena as we mention. 13. What phenomena occur in submarine eruptions ? VOLCANIC PHENOMENA. CRATERS. 107 Let us add that islands which rise to the surface of seas do not always remain. Many of them disappear after a longer or shorter period, either by being washed down by the waves, as is supposed to have been the case with the island of Julia, or by their mass sinking into an abyss formed be- neath them ; the last circumstance doubtlessly happened to an island which was elevated in 1719, near Saint-Michael (Azores), and disappeared in 1723, leaving in its place a depth of seventy fathoms. In the same region there was an island in 1 633, where there is now a bottomless abyss. 14. Crater of upheaval, or elevation. The first effect of an eruption is to burst, by its violence, the crust of the earth in the direction which matters pent up in the interior have taken to escape. The ground, no matter of what nature, is at first raised to a more or less considerable extent, or arched like a bell, and often cracked in every direction ; at once, the explosion occurring, as if by the action of a formidable powder-blast, an opening is made in the form of a funnel, through which often escape gaseous and other matters which caused the event. It is to these initiatory openings, which may be made anywhere, to which the name of crater of elevation has been given, from the necessity of distin- guishing them from all that may subsequently occur in the series of volcanic phenomena. The hillock itself which is produced on the soil, by the first effect, is called the cone of elevation, to distin- guish it from analogous hillocks which are often formed also by the accumulation of incoherent materials ejected from the volcano. 15. Character of these openings. What characterizes craters of elevation, and enables us to recognise them in places where there is no account of an eruption, is, the disposition or arrange- ment of the upheaved strata, being very different from what is everywhere else observed. These beds are here found inclined all round the axis of the cone, as in the section (fig. 188), rising more and more from the base to the summit, and presenting their abrupt escarp- ment " T 1 * the interior of the cavity. Monte-Nuovo is an exam- ple in miniature : the mountain was formed by elevation, hollowed at its summit by ejecting gases and incandescent matters ; and the cavity, which can be examined now, has around it, at an inclination of thirty degrees, strata of different formations, which in all the rest of Campa'nia are horizontal. The semicircle of the somma presents the same characters in the inclined tables of amphige'nic porphyries, and analogous circumstances exist in many other localities. 16. Another character, not less important, and especially useful when the upheaved matters are not divided into beds, is furnished 14. What is a crater of elevation ? What is a cone of elevation ? 15. How are craters of elevation characterized ? 108 VOLCANIC PHENOMENA. CRATERS. us in great craters of elevation by the crevices or cracks which extend from the margin of the escarpment to the external base of the mountain, forming what are named barancos in the Canary islands, where they are so remarkable. One of these barancos (or ravines) much deeper than the others, extends from the foot of the mountain to the bottom of the crater, as is shown in the follow- ing view (Jig. 189). This last character is seen almost always in Fig. 189. View of the Island of Palma. the different localities produced by similar events, as well as in most islands which have been upheaved in our times in the midst of the ocean ; frequently there are many valleys of the same kind. Remarks on the formation of craters. We have mentioned explosion as determining, definitely, the formation of the crate'riform cavity at the sum- mit of the upheaved mass ; however, it is not probable that this circum- stance, which is applicable to Monte-Nuovo, the island of St. George, &c., is constantly seen in all cases; it seems to be even totally inadmissible in certain craters of vast extent known to exist in a number of places. But this explosion is not even necessary. In fact it is easy to conceive that after a fracture, as in fig. 190, which is a correlative result of ele- vation, it may happen that all the erect, eolumri-like masses, and all the elongated points between the rents, might be tumbled down at the same moment, or by a subsequent action. Hence results an open cavi- ty (fig. 191), the margin of which is formed by all the debris, and the depth is in proportion to the sum of the voids or spaces formed by the fractures. On the other hand, it is clear that elevation is produced by some matter, liquid or gaseous, which pushes the crust of the earth and forces it to swell upwards ; now, if it happen that this matter should find exit at some other point, or re- tire again into the bowels of the earth, the upheaved part being left without support may sink into the abyss left beneath it, and conse- quently cause an immense vacuity in the midst of the gibbosity or Fig. 191. hillock, then merely forming a mass 16. How are craters of elevation distinguished when the upheaved mat- ters are not divided into beds ? VOLCANIC PHENOMENA. CRATERS. 109 hollow in the centre, and cracked on the margin. This must have taken place in many cases, and notably in the mass of Etna, (fig. 192), the east- ern slope of which presents a vast excavation, called Val del Bove, which is bounded by high ridges, cracked at various points. Lava of 1822. - Terminal cone. ValdeBove. LavaoflGGO. C.VTANEA. Islands of Cyclops. Fig. 192. Plan of Etna and its environs, according to the relievo of M. Elie de Beaumont. This comment need not be regarded as a simple theoretic speculation ; there are many examples of similar excavations, independent of the effects produced by earthquakes. At the summit of Mount Etna there is one of 1300 feet in depth, which dates from 1832, and many others which were produced at the end of the last or beginning of the present century. Fre- quently lakes are formed on a sudden, sometimes of boiling water, by the sinking of the land consequent on volcanic eruptions, as in 1835, near the ancient Cesarea in Cappadocia ; in 1820, in St. Michael's (Azores), &c. It has also happened that high volcanic mountains have at once sunk, their place being at once filled by deep lakes, as the volcano of Papadayann in Java, in 1772, which carried away with it forty villages built on its sides : as also, in 1638, the peak of the Moluccas, which could be perceived twelve leagues at sea. We know that the summit of Carguarai'zo which rivalled Chimborazo in height, crumbled in 1698, and the same occurred to Capac- TJrcu, also situated on the plane of Quito, a short time before the arrival of the Spaniards in America. Many other facts of a similar kind could be adduced in support of the theory advanced. 17. Effects subsequent to elevation. The crate'riform cavities we have spoken of sometimes remain tKe same as when first pro- duced ; often, however, various volcanic phenomena subsequently occur at different times and in various ways. In this manner it was that the cone of Vesuvius (Jig. 185) was formed in 79 in the ancient crater of the Somina (p. 104) ; that the peak of Teneriffe is found in a circle, the vertical walls of which rise from 600 to 1200 feet; that the volcan of Taal, in Luzon, one of the Philip- pine islarids, is in the centre of a basin filled with water, and sur- 17. Do craters of elevation always remain the same as when first pro- duced ? Give some examples of the secondary effects of eruptions. 10 110 VOLCANIC ISLANDS. rounded by elevated rocks, having a single opening only for entrance &c. Islands which have been elevated in the midst of the sea frequently exhibit phenomena of the same kind. Thus the islands of Santorin, The- resia, Aspronisi, (Jig. 193), which were elevated long before the Christian era, present the appearance of a vast crater of elevation : their slopes are gentle (Jig. 193) externally, but abrupt, on the contrary, towards the centre Theresia. Santorin. Fig. 193. Section of Santorin and adjacent islands. of the circle of which they form the margin. The ground is composed of various strata, inclined outwardly, among which are limestone and argilla'- ceous schist. In the middle of the circle, the depth of which is considera- ble on the borders, all the subsequent volcanic phenomena were produced, and here the three summits of cones successively appeared, which consti- tute three modern islands, and are still preparing new eruptions. Something similar is seen in the Gulf of Bengal, on the Island of Barren, discovered in 1787. It is a vast circle (Jig. 194) formed of high moun- tains, into which the sea penetrates by a single opening, and has a volcan in the centre which was in full activity at the time of the discovery. Fig. 194. View of the Island of Barren in the Gulf of Bengal 18. 'Similarity of configuration in Volcanic Islands. Different volcanic islands which have been formed under our eyes, as it were, in the midst of the ocean, are entirely analogous to those we have mentioned. The island of Sabrina, at the moment of its appear- ance, presented a crater which opened to the south, (jigs. 195, 196), and terminated by an opening, through which issued a current of boiling water: according to the accounts, the island of Julia must have been somewhat analogous ; and the history given by Captain Thayer, reported by Poeppig, shows such to have been the case. On the 6th September, 1835, to the north of New Zealand, this navigator almost witnessed a submarine eruption, which presented 18. How do volcanic islands differ from each other in form ? VOLCANIC ISLANDS. Ill Fig. 195. Fig. 196. Appearance and form of certain volcanic islands. an annular rock, almost on a level with the surface of the sea, in the midst of which was a lagune having a single outlet, and in which the water was burning. Now, these islands appear to be nothing more than points of domes upheaved, like those in the gulf of Santorin, either instantaneously or slowly, and having the summit broken, like Monte-Nuovo. These are true craters of elevation or of explosion, as we would call them ; and as such they may consist of solid rocks, or of various tufas, or even of scoriae accumulated on their borders. The archipelago of the Azores, which have so often witnessed rising from the sea similar islands, which time has destroyed, presents us one which seems to have escaped destruction, to exhibit to us how all those were formed which have disappeared. This is the rock of Porto de Ilhco, which presents a vast circle, into which vessels enter for shelter; its sides rise 400 feet and are composed of volcanic tufa. 19. These phenomena explain to us the origin of a great many islands found in the ocean (Jig- 197), both by the analogy of their form to those we have named, and their nature. Some are in the form of a horse-shoe, having a more -, ^^ or less expanded opening, which //- O"S gives access to the middle of the deep basin they enclose, and in the centre of which isolated volcanic hillocks are occasionally found. Fig. 197. Disposition of certain Others are entirely circular, having islands in the South Seas some of the points of the circle more or less broken, or groups of small islands arranged in a circle, which are more or less promi- nent above the water. 20. Different periods of the formation of a volcan. We may often distinguish in the mass of a volcanic mountain, several dif- o 19. How do volcanic phenomena explain the origin of certain islands ? 112 VOLCANIC PHENOMENA. ferent parts, each of which corresponds to a particular mode of formation. The first gibbosity or hill is, in general, the effect of elevation of the pre-existing soil, which may be of any kind or nature. Afterwards, sooner or later a fissure is formed, which produces either a crater of elevation or a dome of pasty matter, as at Jorullo, clearly detached from the first hillock; and, as a last result, in the midst of one or the other a permanent chimney is formed. Often the formation of the terminal cone then commences, by the scoriaceous matters raised by the melted lava filling the primitive conduit, which overflows the margin of the aperture, or it is ejected into the air, from which it falls again around the centre of eruption, accumulating in cones with a maximum slope of from 30 to 35. These loose scoriae melt on the side towards the inte- rior of the chimney, which they narrow more and more by the suc- cessive cornice-like projections they form, and in this way conceal the true diameter of the crater. 21. It is rare that these three kinds of formations are all found in the same volcano ; but we always find the gibbosity produced by elevation, and one or the other of the secondary domes. At Tene- riffe there is a broken dome Avhich was upheaved in the middle of a crater of elevation. At Vesuvius, from the constant solidity of the base, and other circumstances, we may infer the existence of a central nucleus, produced in the same way as a dome, in the year 79, afterwards enveloped in loose materials, and bearing on its summit a true cone of scoriae. At Etna (fig. 198) we clearly Fig. 198. View and profile of Etna, and the surrounding country, r- distinguish the primitive hill or gibbosity, showing sheets or coats of ancient upheaved lavas, on the middle of the slightly- arched surface, which all this part of the island presents ; it is terminated by an almost level surface, the Piano del Lago, in the midst of which rises the terminal cone of scoriae, regularly cir- cumscribed on all sides, and clearly separated from the base on which it was formed. On the slopes are small cones of eruption, formed here and there, at different times, which have since contri- buted to the swelling up of the whole of the surrounding land. 22. It is clear, that the cones of scoriae constructed in the man- ner just mentioned, at the bottom of volcanic gulfs, cannot be very solid ; they often change their form at every eruption. Sometimes the edifice rises more and more ; sometimes, on the contrary, it 20. Are volcans always characterized by the .same kind of formations ? 21. Do we always find in one volcano all the kinds of formation ? What one is always found ? 22. What are the characters of cones of scorice found at the bottom of volcanic gulfs ? INTERIOR OF CRATERS. crumbles into more or less considerable shreds, and hence cones are deeply broken in all manners of shape. Sometimes the whole mass is swallowed at once in the abyss it covered, and is recon- structed by subsequent eruptions. This took place in the terminal cone of Etna, which has several times disappeared entirely Cleaving an immense aperture, without parapet, in the midst of a little plain which crowned the original gibbosity or hill. At Vesuvius only the upper part of the cone has ever been modified. 23. Interior of craters. Contrary to the expectation of all those who visit volcanoes, the interior of craters seldom possesses much that is worthy of observation. After great eruptions, during which they cannot be approached, these cavities (which are of conical form, and have a more or less extensive diameter at the top, with a bottom apparently formed of a sheet of consolidated lava, which covers the principal chimney) ordinarily present for observation merely jets of sulphurous vapours, escaping here and there from fissures in the soil, from interstices in blocks of crumbled scoriae, or a greater or less number of small cones raised up in different places. Occasionally we see one or more gulfs, sometimes filled with vapours which escape continually, and sometimes revealing the incandescent lava in the depth ; sometimes silent and dark, inspiring with terror, but without possessing the least interest for observation. In long intervals of crises, traces of volcanic action often entirely disappear ; in certain instances even the sides of the crater become covered by vegetation, as is related of Vesuvius before the eruption of 1631. 24. There are, however, some observations worthy attention. The crater of Stromboli, which has been in continuous activity from the most ancient times, still presents phenomena identical with those recorded by Spallanzani, in 1788. It is constantly full of melted lava, which alternately rises and sinks in the cavity. Having reached to twenty-five or thirty feet of the edge, this lava swells, is covered with large vesicles or blisters, which speedily burst with a noise, permitting the escape of an enormous quantity of gas, and projecting scoriaceous matters on all sides. It immediately sinks, after an explosion, then rises again, to produce the same effects, which are in this way repeated at regular intervals of some mi- nutes. 25. If the lava of Stromboli were less fluid, it is conceived, that having reached to its highest point, it would there stop, assume an arched form, and become consolidated into a more or less elevated cone ; and then, if an explosion occurred at a certain instant, a new conical crater would be found in the middle of the old one. This 23. What is found in the interior of craters ? 24. What is remarked of the crater of Stromboli ? 25. What would probably be observed, if the lava of Stromboli were less fluid than it is ? 10* 114 INTERIOR OF CRATERS. explains what frequently takes place in volcanoes, and, for exam- ple, at Vesuvius (fig. 199), where domes have been raised which remained for a long time, and were subsequently broken, giving passage to lavas, and finally sank into abysses left beneath them. Certain, craters, having a widely extended bottom, often contain hills of considerable height, which have had an origin such as we have described ; either the lava is arrested at a certain height, in Fig. 199. Adventitious Crater > in the middle of Vesuvius, in 1829. form of a cap, or swelled up at different points, or elevations took place in different matters which had filled the cavity. 26. Sometimes, in place of lava, there is found at the bottom of craters boiling sulphur, as was seen at Vulcano, and, on a larger scale, at the volcan of Taal, in the island of Luzon, and at that of Azufral, to the north of Quito, in the Andes ; hills, and even domes of sulphur, are also mentioned, as M. Boussingault observed at the volcan of Pasto. A crater now often mentioned by voyagers is that of Kirauea, on the island of Hawaii, one of the Sandwich group. This vast cavity is three and a half miles long and two and a half wide, and over a thousand feet deep : Captain Wilkes, in his narrative of the United States Exploring Expedition, states that " the city of New York might be placed within it, and when at its bottom would be hardly noticed. A black ledge surrounds it at the depth of 660 feet, and thence to the bottom is 384 feet. The bottom looks in the 26. Is anything found at the bottom of craters besides lava ? VOLCANIC PHENOMENA. SOLFATARAS. 115 daytime like a heap of smouldering ruins. The descent to the ledge appears to the sight a short and easy task, but it takes an hour to accomplish. "All the usual ideas of volcanic craters are dissipated upon seeing this. Tiierc is no elevated cone, no igneous matter or rocks ejected beyond the rim. The banks appear as if built of massive blocks, which are in places clothed with ferns, nourished by the issuing vapours. "What is wonderful in the day, becomes ten times more so at night. The immense pool of cherry-red liquid lava, in a state of violent ebullition, illuminates the whole expanse, and flows in all directions like water, while an illuminated cloud hangs over it like a vast canopy." 27. Solfata'ras. There are a great many craters which for a long time have not given exit to any lava, and are reduced to dis- engaging, in greater or less abundance, sulphurous gas, which escapes by a multitude of fissures in the soil, and often accompa- nied by aqueous vapour. Hence the name of Solfata'ra has been given to those places where these phenomena are more or less developed. Thefe are some craters which seem to have been always in this state. Such, for example, is the Solfata'ra of Pouz- zouli, in the kingdom of Naples, which is a vast crater of eleva- tion, at the bottom of which are found broken volcanic rocks, daily decomposed by the vapours. This solfata'ra is of the highest anti- quity, and appears never to have presented other phenomena than those now observed. When in repose, volcanic craters become more or less active solfata'ras. 28. It is not uncommon to find one or more lakes, frequently of great depth, at the bottom of craters and solfata'ras. The waters they contain are sometimes quite pure, but they are often .charged with various salts, or sulphurous or sulphuric acid, as was seen in the volcan of Teschem, in the island of Java, prior to 1817, the year when this mountain was entirely destroyed by the action of gas. 29. Commencement of eruptions. Continuous emissions of gas or scoriaceous matter from certain volcans, must not be confounded with eruptions, which are sudden events, fortunately transitory, often bringing desolation over an entire country. When an erup- tion is about to take place it is ordinarily preceded by earthquakes, after which it suddenly occurs with more or less noise. If a volcan already exist in the country, an eruption begins by pouring out abundant fumes, composed of various gases and aqueous vapour, then pulverulent matter called volcanic ashes, the quantity of which is sometimes immense ; then follow directly, when they do not appear from the beginning, fragments of red-hot porous stones, called rapilli or lapilli and pouzzolani, more or less considerable blocks of solid matter, which are sometimes ejected to great dis- 27. What are Solfata'ras ? 28. What is the character of the water of lakes found in craters ? 29. How is the commencement of eruptions characterized I What are volcanic ashes ? What is rapilli ? What are volcanic bombs ? What is tu'fa ? 116 VOLCANIC PHENOMENA. ERUPTIONS. tances ; and lastly, portions of melted matter torn from the lava filling the crater, and becoming rounded by their motion through the air, form what are called volcanic bombs. From all this we have, amidst violent detonations, immense bundles or masses of various matters projected to great heights, lighted by reflection from the melted lava, part of which fall at greater or less distances, ac- cording to their weight and the force with which they are impelled. Ashes, rapilli, or pomice then produce in the vicinity of the volcan, sometimes even at a distance, considerable deposits, which becoming solid by their weight and by water, form what is termed volcanic tufa,pumice tufa, and various conglomerates. The vapours and ashes ejected from volcanoes sometimes form enormous clouds, frequently dense enough to intercept the light of day, and shroud the whole neighbourhood in darkness. These clouds, driven by the wind, are sometimes carried to the distance of twenty, fifty, and even two hun- dred leagues. This happened in 1812, when the ashes of Saint Vincent, in the Antilles, were carried to Barbadoes, and so darkened the air that persons could not see their way. The ashes of Vesuvius were carried in 1794 to the end of Calabria; and it was found even in Procopus, that during the eruption of 452 they were conveyed as far as Constantinople. What occurs at the bottom of seas during eruptions is not seen ; but it is clear that the ejection of earthy matters, rapilli, and pumice, are not less abundant, because we find at these times on the surface enormous quanti- ties of them, and in land upheaved, there are seen distinctly deposits of volcanic tufa, pumice tufa, and conglomerates, precisely like those formed on land. 30. Appearance of melted matters. The phenomena mentioned are sometimes the only effects of an eruption ; but most generally they are only the precursors or sequents of the expulsion of melted matter, which soon appears under different forms. Sometimes these matters, most frequently in mass, rise in cones or domes above the very orifice from which they issued, sometimes entire, sometimes vertically perforated in the centre, sometimes suscep- tible of being pushed further out. This happened at Jorullo, and again and again in the gulf of Santorin, and the same must occur in a great many other localities. 31. Under other circumstances, the crater first formed at the summit of a volcan is completely filled with melted matters ; these soon break a passage at a greater or less depth, pouring out tor- rents, which furrow the side of the mountain, and run to the plain, where they spread more or less. 32. Form of currents. If fissures or cracks of eruption be formed at the foot of a volcano in a flat country, the lava escaping from it at once forms broad horizontal sheets in the middle of the plain. This occurred in Iceland in 1783; crevasses formed in the plain at the foot of Skaptar-Jokul, a high volcanic mountain of the 30. What is the form of melted matters ejected from volcanoes ? 31. How are lava-currents formed? 32. What is the form of lava-currents ? VOLCANIC PHENOMENA. LAVA-CURRENTS. 117 country, and an immense volume of melted matter escaped from them. This immediately spread over the soil, covering eighty square leagues, filling up all depressions, and forming a vast lake of fire of considerable depth. 33. But this is not always the case ; the current often forms on more or less inclined slopes, and the lava forms true currents on their surface, of greater or less length, a part of which adheres to the land in consequence of cooling, and in evidence of its passage. After its exit from the bosom of the earth, the melted matter soon cools an the outside, solidifies, wrinkling and cracking in every direction, and thus acquires a crust, ordinarily porous, the thickness of which becomes more or less considerable. This crust prevents the liquid or paste it envelopes from spreading, and confines the current to a certain thickness ; also, from its slight faculty of con- ducting heat it prevents the interior lava from cooling, which, from this cause, goes on very slowly. Lavas have in fact remained liquid or pasty, and preserved a high temperature for a very con- siderable time ; some are cited as still running on very gentle slopes, ten years after their ejection, and others which gave off vapour twenty-six years after their exit from the bosorn of the earth. 34. If after the external cooling the volcanic spring continues to furnish melted lava, the current takes place in a kind of con- solidated sack which is formed ; a sack which then strives, as it were, in all directions, is broken and mended successively ; this causes the twisting and various irregularities in the current of lava. When the source is stopped, the matter which escaped from it does not continue to flow the less in the sack enclosing it, but the latter successively flattens, and the middle is effaced, leaving a more or less elevated roll or ridge on the margins. This is first seen at the upper part of the current, then successively to a point where the liquid matter, becoming more and more viscid, has not suffi- cient force to drag after it the solid parts formed, to break or push them forwards. The lava then stops at the bottom of the sack, terminating fig. 2QQ. Lava-current arrested in a club-like mass (Jig. 200). The ^ on a sl P e - form, direction, and extent of these lava-currents vary according to circumstances, such as the degree of inclination of the mountain sides, and the nature of the lava itself. Some volcanic products are so pasty they cannot run, but remain over the aperture, as occurs with certain trachytes, which then form more or less elevated domes. Others, such as various obsidians, which seem to cool and harden quickly, are sometimes arrested in form of great tears, 33. Do lava currents cool rapidly under all circumstances ? 34. Is the form, direction, and extent of lava-currents always the same ? 118 VEINS OF LAVA, OR DYKES. even on steep slopes, as at Teneriffe. On the contrary, stony lavas which cool slowly and long remain fluid, are not arrested except on a horizontal plain. 35. Various characters of the same lava. From what has been stated, it is certain that lavas cannot accumulate to a great thick- ness, or spread in sheets, except on a horizontal plain. The struc- ture of lava depends, in a degree, on its external arrangement. The vein, which is behind -the current, on a veiy steep slope, is, in parts, thin, scoriaceous, corded, and always very porous. On less steep slopes, the surface of pieces is more united, the pores are smaller ; on descents, at an angle of from three to five degrees, the dislocated parts are in plates of greater or less thickness, the structure of which presents a certain uniformity, and the centre is sometimes a little more compact, if the thickness is sufficient. In great flows, causing great accumulations on plains, where the depressions are filled up, all the inferior part becomes a compact, and, more or less, crystalline mass, which is porphyritic, because then it cools slowly and tranquilly ; in this case it is frequently divided, through its whole height, into columnar masses, generally normal on the cooling surfaces, and porous at the upper part only ; this is seen at Vesuvius and Etna, where the lava is very thick, and at Iceland in the immense deposit formed by the eruption of 1783. 36. Veins of Lava, or Dykes. It frequently happens, that in volcanic eruptions there is formed, on the sides of the mountain, crevices of greater or less breadth, through which the lava comes to the surface of the soil. These cracks are remarked for a long time after their formation, either from remaining partly open, or from the rapilli with which they are filled, leaving a kind of ditch, which may be readily followed. They may be also recognised by the partial and crate'riform excavations of these debris, which all have the same line of direction ; sometimes they are distinguished by rolls of scoria on the edges, which escaped while the lava was boiling in the interior; they also exhibit conduits of lava, which unite to each other the different cones of eruption formed on their line of direction. It cannot be doubted that these cracks remain partly filled with the lava to which they gave passage, giving rise to veins, or dykes. Sometimes the lava flows above the crack or fissure, forming sheets on the surface. Sometimes a coat or bed of lava is found in evident communication with a dyke, which, after having passed up through all the lower deposits, stops in- the middle of it (Jig. 201) ; and it is not rare to find several beds of lava lying one above the other, each one corresponding with a par- ticular dyke (fig. 202), to which, no doubt, it owes its origin ; the 35. Are the characters of lava always the same ? 36. What are dykes ? Are all dykes precisely the same in character ? GASEOUS VOLCANIC PRODUCTS. 119 most recent of these dykes or veins being the one which has passed up through all the inferior beds or tables, to form the upper one. Fig. 201. Fig. 202. Sheets, or tables of Lava, with their corresponding Dykes. 37. The matter that constitutes dykes is rarely porous, except sometimes on the sides towards the rock encasing it ; it is fre- quently even of a finer grain than the table or bed in which the dyke terminates ; its mass is sometimes divided into prisms per- pendicular to the sides of the fissure, which were the cooling sur- faces. This matter generally re- sists atmospheric influences, and it frequently happens that the surrounding rock being degraded, carried away by external agents, f the dyke remains projecting on the side of the escarpment (jig- 203), or even rising out of the Fig-. 203. Dyke brought into view by earth like a wall. destruction of surrounding rocks. 38. Gaseous volcanic products. Volcanic phenomena are ac- companied by the production of great quantities of various gases, some permanent, others condensable or soluble. These products consist for the most part of watery vapour ; but they are found to contain also various acids, and other matters sublimated from the volcano. Most of these gases are fatal when breathed. Gases, always at a high temperature and mixed with the vapour of water, act powerfully on the solid surrounding- matters ; they disaggregate and decompose them in all ways, reduce them to powder, to mud, and form new compounds of every kind. This happens in all solfata'ras, where it is often necessary to be cautioned against falling into masses of muddy matter, which is sometimes very hot. But nothing is comparable in this respect to the volcans of Java; the acid and aqueous vapours which are there in great abundance, destroy the rocks and form a paste of them, which speedily becomes incapable of resisting the explosive action of the interior. These fearful eruptions take place, not of lava as in ordinary volcanoes, but of enormous masses of boiling water, charged with sulphuric acid and thick mud, which destroy everything in their way, and cover the whole country with a sulphurous slime the matter of which is called buah. This happened in 1822, on the eruption of Gallung-Gung, which, with earthquakes and horrible noises, was considerably sunk, truncated at the summit, and entirely overturned. Torrents of hot sulphurous water and mud issued from rents 37. What is the character of the matter constituting dykes ? By what means are dykes sometimes naturally brought into view ? 38. What are the characters of the gaseous products of volcanoes? How do gases affect surrounding solids ? Do volcanoes ever eject mud 1 In what condition is lava when gases are disengaged from it ? 120 SOLID VOLCANIC PRODUCTS. in the side of the mountain ; and many inhabitants were swept away in the waters, or buried under deposits of mud, during the 8th and 12th days of October. Muddy eruptions of Quito. The volcans of Peru, which like those of Java have rarely produced lavas, vomit from their sides torrents of mud called rwoya, sometimes sulphurous like the luah of Java, at others carboni'ferous. This happened in 1698, when the volcan of Carguarai'zo crumbled, covering more than 2500 square miles with mud ; and in 1797, when the village Pel- lile'o, near Rio-Bamba, was buried under a mass of black mud, &c. What especially characterizes the eruptions in Peru, and makes them very strange, is that the muddy waters which spring from the bosom of the earth, are filled witli small fishes, species of which live in the neighbouring lakes; and the quantity of them has been sometimes so great as to excite epidemic dis- eases by their putrefaction. Gases disengaged from Lavas. It can be readily conceived that gases and matters of various kinds may be disengaged from the bowels of the earth, through fissures communicating with its surface ; but what is most remarkable, they are also disengaged from lavas, although on leaving the volcano they have no properties in common. As long as the lava is fluid and at a high temperature nothing escapes from it, but the moment it begins to harden, and consequently to cool, gases are disengaged in more or less quantity. Streams, matters which filled the lowest levels, then constantly emit the vapour of water, hydrochloric acid, sal ammoniac, which are de- posited on the snrface, to say nothing of realgar, iron, &c., which are some- times sublimed in the fissures or cracks. Consequently the lava itself must contain these matters, which remain engaged in it, we know not how, while the mass is fluid or pasty, and which are disengaged just in proportion as it solidifies and cools, and in a manner which leaves no after-trace. It is supposed that all these matters give to porous lavas, the power of preserving their fluidity for a much longer time than similar substances artificially prepared. 39. Solid products of Volcanoes. All the solid substances which volcanoes produce in great abundance, belong to the group of si'li- cates, generally anhy'drous si'licates, and particularly to that divi- sion of those confounded under the name of feldspar. These are generally compound rocks, and substances more or less mixed, the principal base of which it is difficult to separate, and therefore they cannot be accurately classified : we are forced to resort to artificial divisions. 1st. 7'rdc/n/te (from the Greek trachus, rough) is a rock often rough to the touch, as its name indicates, composed of albite or rya'colite, sometimes compact, of a ceroid or vitreo-resinous, and occasionally earthy lustre, sometimes crystalline, the mass being finely porous, containing crystals of the same substances, and often also hornblende and black mica. Albite (from the Latin, o/feus, white), a mineral so called from its colour, which contains si'lica, alu'mina, and soda. A lamellar variety is found at Chesterfield, Mass., called Cleavelandite, in honour of Professor Cleaveland. Rya'colite (from the Greek, ruax, a stream, and lithos, stone), is a glassy mineral, of a greyish-yellow to white colour, or colourless. Besides si'lica, alu'mina, and soda, rya'colite contains potash. 39. What are the general characters of the solid products of volcanoes ? What is tra'chyte ? SOLID VOLCANIC PRODUCTS. 121 Hornblende (from the German), a kind of dark or black variety of mine- ral, belonging to the same group as tre'molite, acti'nolite, asbe'stus, &c. Mi'ca (from the Latin, mico, I shine), is a mineral generally found in thin, elastic laminae, soft, smooth, and of various colours and degrees of transparency. It is one of the constituents of granite and its associate rocks. 40. 2d. Obsi'dian (from the Greek, opsis, view, or after Obsi- dius, who first found it in Ethiopia}, is a homogeneous, vitreous substance of various colours. By me ancients it was used in. place of glass, and is also called volcanic glass. It consists of si'li- ca, alu'mina, with a little potash and oxide of iron. This substance is produced abundantly in the islands of Lipari and Teneriffe, the volcans of the Andes, and wherever volcanic apertures open in tra'chyte. 41. 3d. Compact lava. A substance with a compact base of a deep colour, most frequently formed of labradorite, containing crys- tals of the same substance, or of the feldspa'thic group in general, which in the mass presents a more or less distinct porphyritic struc- ture. Crystals of py'roxene, of am'phibole, black mica and peri- dote are also occasionally found. La'bradorite Labrador spar. A beautiful variety of opalescent feldspar from the coast of Labrador : it exhibits brilliant and mutable tints of blue, red, green and yellow, and is susceptible of a good polish. It is cut into small slabs, and employed in ornamental jewelry. It is a si'licate of alu'- mina, lime, and soda, with traces of oxide of iron. Py'roxene (from the Greek, pur, fire, and zenos, stranger). The augite, supposed to have pre-existed in the volcanic minerals containing it, and riot to have been formed by fire. Am'phibole (from the Greek, amphibolos, equivocal). A name applied by some mineralogists to hornblende, because it may be mistaken for augite. Peridote, or Chrysolite (from the Greek, chrusos^ gold, and lithos, stone), from its colour. The topaz of the ancients. These substances constitute the centre of thick currents, the in- ferior part of the mass formed in excavations or hollows ; they are often divided into prismatic columns. 42. 4th. Porous, or scoria'ceous lava. A substance of the same nature as the preceding, but rarely having crystals embedded in it, and its structure is porous, or cellular. These lavas consti- tute the upper parts of thick layers, and envelope lava currents and streams which rest on the surface of the ground. 43. 5th. PoKzzolani, volcanic tufa. Masses of small scoria'- ceous fragments, or rapilli, accumulated around volcans, or earthy substances, which contain them in greater or less quantity. Pu- mice-tufas are formed of fragments of pumice, and trdchytic con- glomerates of fragments of tra'chyte, unite'd by crystalline or earthy cement. 40. What is obsi'dian ? 41. What is compact lava? 42. What is scoria'ceous lava ? 43. What is volcanic tufa ? 11 122 EFFECTS OF WATER. 44. 6th. To these may be added scoriee in tears, irregular stala'ctites scattered on the surface of volcanoes, and volcanic bombs, which are sometimes found at considerable distances. 45. Volcanoes furnish annually but a small quantity of materials to the solid crust of the globe, and the upheavals they cause pro- duce very slight change in the elevation of countries where their action is manifest. Nevertheless, if we remember that a great number have been in action since the time of history, and observa- tion shows that a great many more were previously in action, we are led to the conclusion that volcanic substances are important, and their presence must have occasioned great modifications on the surface of our planet. LESSON VII. INFLUENCE OF EXTERNAL AGENTS ON THE SURFACE OF THE EARTH. Effects of the Atmosphere Degradation Effects of Winds Dunes Effects of Lightning. EFFECTS OF WATER. Dissolving power Softening power Denudation Erosion Effects of weight of Water Punning Waters Debacle of Lakes Mud-torrents Slope of Torrents and Rivers Rolled Flints Transportation by Ice and Gla- ciers Action of Waves Deposits formed by Water Geysers Structure of sedimentary Deposits 7a'lus Effects of Transport or Drift Effects of oscillation in Waters Nature of Deposits from Water Coral Reefs Polypa'ria Peat- bogs. 1. Atmospheric Effects. Variations of temperature, the air, winds, dryness, and moisture, act very perceptibly on most mine- ral substances ; there is not a rock on the surface of the earth which does not present an appearance, externally, totally differing from what is seen internally, when it is broken. This is everywhere seen in escarpments formed by making roads, in mountainous countries, where it is necessary to cut through rocks ; the exterior is discoloured, and more or less extensively disaggregated, corn- pared with the freshly-exposed interior. These effects are not solely produced by a great lapse of time ; a few years are sufficient for them to be shown, not only on the surface, but to considerable depths : these effects are seen in ancient quarries of marble, or of 44. What other solids are produced by volcanoes ? 45. What influence do volcanoes exert, on the elevation of countries ? 1. How are the effects of the atmosphere on rocks manifested? How does frost act on rocks ? Is a very long period of time necessary for the atmosphere to produce its effects on rocks ? ATMOSPHERIC EFFECTS. 123 certain granites, and in dressed stone. The effect is more rapid and perceptible, in proportion to the susceptibility of the substance to imbibe moisture, and to dry again ; alternations which produce a very rapid disaggregation, when frequently repeated, as is gene- rally the case in mountains. The substances which degrade most easily, are those of a granular structure, either earthy or crystalline ; those of a foliated structure ; or compact masses, fractured and split on the surface, such as are often seen in mountains. Frost, when it attacks water absorbed by a body, is also a powerful cause of destruction, because the expansion consequent upon it produces a multitude of cracks in all directions. As long as the cold con- tinues, its parts are held together by ice as by a cement ; but when a thaw comes, the. whole falls in scales, grains, or dust. Mountains cannot be visited without meeting' evident traces of degrada- tion of this kind. In limestone escarpments (Jig. 204), we see parts of loose Fig. 204. Fig. 205. Daily effects of degradation in mountains. texture, more or less hollowed out, and the more solid banks remain. Hence the falling of the latter, which are successively detached in more or less voluminous blocks. In high mountains (fig. 205), often formed of in- clined strata, which present their cuts or planes to the slope, we observe the most marked degradations ; parts are constantly detached, particularly at times of most sensible atmospheric variations; at the instant of thaw, enor- mous avalanches of stones occur, and roll down the sides with astonishing rapidity, sweeping everything in their course ; sometimes great blocks, and considerable portions of the mountain fall with tremendous noise. Hence the enormous debris which accumulate at the base, sometimes covering a great extent 2. Degradations attributable to these effects. The degradation which many rocks present is generally attributed to atmospheric influences, lo g continued. Almost all rocks, in fact, are more or less deeply changed, and are in a state of much less solid aggrega- tion, much less homogeneous, on the surface, than they are inter- nally. In almost all quarries, it is necessary to remove a great mass of matter, before obtaining blocks which are homogeneous, solid, free from cracks, and possessed of the bright colours which are ordinarily sought; this is especially the case with marble, and generally, also, with compact limestone. Certain granites are so deeply disintegrated, that the whole surface of the soil presents a 2. What is meant by degradation of rocks ? What are rocking stones ? 124 ACTION OF WINDS. DUNES. mass of gravel in rounded hills, gullied by the rain in all directions. Frequently we find these granites on the surface of the soil, in great rounded blocks, piled up one on the other (Jig. 206), in the strangest manner, sometimes in unstable equilibrium, and suscep- Fig. 206. Degradation of granite as seen in different places. tible of oscillating from the slightest effort ; these are termed rock- ing stones, in some localities. In mountains where the granite is easily decomposed, we often remark that the mass, more or less cut, is in a sort of horizontal stories, divided by vertical fissures, so as to present a kind of agglomeration of irregular paral- le'llipipeds. It is supposed that, in consequence of atmospheric influences, these angular blocks are altered on their faces and angles ; that the disag- gregated parts are successively detached, producing rounded masses, piled on each other like cheeses, as we now see, sometimes, isolated on the surface of the soil. 3. Action of winds dunes. Although winds act but very feebly on solid mineral masses, they exert an important influence on deposits of fine movable sands. We know that in the deserts of Africa and Arabia, the winds raise immense clouds of burning sands, conveying them from place to place, and suddenly produc- ing vast hills, sometimes quite high, which a new gale again de- stroys. All sandy sea-coasts are exposed to similar effects ; the least gale sets the sands in motion, and produces, on the previously uniform surface, a multitude of wrinkles or ridges, parallel to each other, separated by a greater or less interval, and each presenting a gentle slope towards the wind, and a more abrupt declivity on the opposite side, as represented (fig. 207); the next gust of wind sets all these ridges in motion, and each one is soon found to occupy the space which separated it from the preceding ridge. This pheno- menon of dunes, or downs, is seen in miniature on the sea-beaches ; and they sometimes invade immense tracts on adjacent planes. These hills, placed one behind the other, in a direction perpendicu- lar to that of the prevailing winds, are constantly in motion, and constantly advance towards the interior of the land ; the wind from 3. What are dunes ? How are they formed? What is meant by talus ? At what rate do dunes advance ? EFFECTS OF WATER. 125 seaward drives the sand from the foot of the hillock (fig. 207, a), to its summit (6), whence it falls in the line /;, c, forming at this point a falling talus, always more abrupt than the first or rising Fig. 207. Fig. 208. Progress of dunes, or moving sands. ta'lus. The result of this is a single hillock, a b c, taken sepa- rately (fig. "ZOS), which grows behind, if new sands be furnished in front, or it is displaced, if the same sands are continually re- moved. Now, the wind acting on all these hillocks at the same time, the mass formed by them is found to have moved a certain di-stance inland, in a short time, while new heaps are formed in front, at the expense of the sands freshly washed up from the sea. It is calculated that dunes advance, in this way, twenty or thirty yards a year; so that it is evident there must have been a time when they were far from the places they have invaded. A great many localities are known, which have been submerged by these seas of sand. 4. Lightning sometimes produces remarkable effects ; in a great many places and on various rocks, traces of fusion by thunderbolts in high mountains have been observed. According to the observa- tions of Friedler, when lightning penetrates sand, it often forms narrow, irregular canals to a great depth, the sides of which are consolidated by the fusion of quartz itself; and there are instances where considerable portions of rocks have been turned round, torn from their places and hurled to great distances by lightning. 5. Effects of Water. Water plays a very important part in the changes which are taking place on the surface of the globe ; some- times by its dissolving power, but more frequently by its softening action, its weight, and especially by the motion that may be com- municated to it, and by the transporting power resulting from its rapidity. The extent and importance of modifications from this agent ought to be understood. 6. Dissolving power. Water exerts a chemical action an some substances which it dissolves, either directly or by means of the carbonic acid it may contain. It acts directly on some salts which it meets here and there, or on some deposits of sulphate of lime, which it corrodes in various ways. When more or less charged with carbonic acid it acts on calcareous rocks, either under ground or where they crop out on the surface ; or in high mountains at the time snows are melting. In this case, the water generally pos- sesses itself of the carbonic acid contained in the air, in greater 4. What are the effects of lightning on rocks ? 5 By what properties does water produce its effects on rocks ? 6. What effects result from the dissolving power of water ? 126 EFFECTS OF WATER. quantity than at other times, in consequence of its low temperature ; and running over calcareous masses, it forms furrows which gra- dually deepen, and sometimes cause very considerable falls of rock. These slow effects of water are particularly remarked in the Alps and Pyrenees, where the snows remain a part of the year, and melt by degrees in the fine season. 7. Softening power. Water, by penetrating argilla'ceous beds, sometimes softens them so much, that they cannot remain on the slopes they occupied, and fall from their own weight ; this is the cause of many falls or slides in sedimentary formations. One of the most remarkable catastrophes of this kind happened in 1806 at Ruffiberg or Rossberg in Switzerland, after a very rainy sea- son. The argillaceous matters which cemented the rolled flints forming the mountain becoming softened, a mass of more than 50,000,000 of cubic yards was suddenly detached, and precipitated into the valley, forming in it hills sixty yards high, and burying several villages under masses of mud and flints. We often see, on a small scale, thick beds of rock gently slide to the bottom of valleys, on softened argilla'ceous beds which supported them, and tranquilly displace plantations and even the inhabitants on them, without the proprietors perceiving it at the first moment. 8. Waters which filter through rocks to argilla'ceous layers which may arrest them, and on the plane of which they are directed to the surface, sometimes soften these substances also, carrying away parts successively, and especially sands that may- rest on them, laying bare in this way underlying beds : this is termed denudation. There results from this, at the point where the water breaks forth from the declivity of hills, mo're or less ex- tensive voids, which leave the solid superposed masses without support, which are then dislocated in different ways (fig- 209) and Fig. 209. Fig. 210 Escarpments produced by the action of water. soon overthrown. This is frequently seen in certain escarpments, at the base of which are found argilo-arena'ceous layers which con- duct the springs externally. 7. What are the effects of the softening power of water on rocks ? 8. What is meant by denudation ? EFFECTS OF WATER. FALLS OF NIAGARA. 127 9. Erosion. Something analogous happens when waters, which washing the foot of a mountain, meet there with substances that they can easily soften or disaggregate. These substances being destroyed, the upper parts of the soil are soon undermined, and more or less considerable falls occur. This takes place on sea- coasts, on the shores of lakes or rivers where more or less elevated escarpments are formed, and more and more degraded. The same thing happens sometimes at the foot of cascades which fall over rocky peaks (Jig. 210), forming alternately calcareous and argilla'ceous deposits ; the latter are disaggregated, and borne away little by little by the waters which exude on the parietes or jet forth after the fall, and other layers being undermined must fall sooner or later from their own weight. In this case the cascade cuts deep into the soil, and the same being successively repeated, necessarily forms a gorge or bed the whole length of the rivulet, which deepens more and more. It is in this way that the falls of Niagara, by which the waters of lake Erie are precipitated into those of lake Ontario, have sensibly receded since the discovery by Europeans, and probably have excavated the deep bed through which they afterwards escape. " The waters, after cutting through strata of limestone, about fifty feet thick in the rapids, descend perpendicularly at the falls (of Niagara) over another mass of limestone about ninety feet thick, beneath which lie soft shales of equal thickness, continually undermined by the action of the spray, driven violently by gusts of wind against the base of the precipice. In, consequence of this disintegration, portions of the incumbent rock are left unsupported, and tumble down from time to time, so that the cataract is made to recede southwards. The sudden descent of huge rocky fragments of the undermined limestone at the Horse-Shoe Fall, in 1828, and another at the American Fall, in 1818, are said* to have shaken the adjacent country like an earthquake. According to the statement of our guide in 1841, Samuel Hooker, an indentation of about forty feet has been produced in the middle ledge of limestone at the lesser fall, since the year 1815, so that it has begun to assume the shape of a crescent, while within the same period the Horse-shoe Fall has been altered so as less to deserve its name. Goat- Island has lost several acres in area in the last four years (prior to 1841) ; and I have no doubt that this waste neither is, nor has been, a mere temporary accident, since I found that the same recession was in progress in various other waterfalls which I visited with Mr. Hall, in the state of New York. Some of these intersect the same rocks as the Niagara for example the Genesee at Rochester ; others are cutting their way through newer forma- tions Allan's creek, below Le Roy, or the Genesee at its upper falls at Portage. Mr. Bakewell calculated that, in the forty years preceding 1830, the Niagara had been going back at the rate of about a yard annually ; but I conceive that one foot per year would be a much more probable conjecture, in which case 35,000 years would have been required for the retreat of the falls from the escarpment of Queenston to their present site, if we could assume that the retrograde movement had been uniform throughout. This, however, could not have been the case, as at every step in the process of excavation, the height of the precipice, the hardness of the materials at its 9. What is meant by erosion ? What are the effects of erosion ? 128 ACTION OF RUNNING WATERS. base, and the quantity of fallen matter to be removed, must have varied. At some points it may have receded much faster than at present, at others much slower ; and it would be scarcely possible to decide whether its ave- rage progress has been more or less rapid than now." LyelVs Travels in North America. 10. Effects of weight. Water acting by its own weight like other bodies, evidently often contributes to such land-falls as we mention, and also exerts a powerful action on the dykes and bar- riers which retain it. We see the unhappy effects of inundations, to which certain countries are subject from their vicinity to rivers, lakes, or seas, retained by natural or artificial dykes. 11. Action of running waters. To the softening action and weight of waters is often added a new power, from the motion they acquire by running over steep descents. This force is some- times prodigious. The effects are seen after storms which pass over moveable substances, in the deep ravines found to have been excavated. These effects are in proportion to the mass of water, and the rapidity of its motion on a particular point. When a hur- ricane or violent storm bursts on a mountain, the soil is often found, unless it consist of living rock, removed and gullied to great depths. The numerous fissures on the surface of rocks facilitate the action of waters, and a considerable mass of fragments is soon detached, which increase more and more the destructive power of the current. Then blocks of every size are loosened, torn from the mountain and transported to great distances, multiplying the effects ten or even a hundred fold, in proportion to their mass and rapidity of motion. Hence we have great ravines on slopes that were pre- viously unbroken, and an immense accumulation of debris at the foot of the mountain, and especially where the soil or the swiftness of the stream abated. Torrents swollen by circumstances of this kind, or by the sudden melting of snows, also produce frightful ravages; they sweep everything in their way, even the living rock, which they soon attack forcibly by the fragments and blocks they swiftly urge along. Nothing is more terrible than this kind of water-course, and to form an exact idea of the effects one must see a gorge through which it has passed, sometimes rolling along rocks measuring ten or fifteen cubic yards. 12. Debacle of Lakes. Lakes which sometimes form in valleys^ by avalanches or falls of land, constituting a barrier which retains them, are most fearful in their debacle (sudden escape of their waters from breaking of their barrier), in consequence of an enor- mous mass of water rushing forth in a few seconds. Scarcely does a flow begin through a few rents, before the first opening rapidly enlarges, and in an instant the whole dyke is carried away. An 10. Does the weight of water contribute to its effects ? 11. What are the effects of running waters ? 12. What is meant by debacle ? What are the effects of debacle ? SLOPES OF TORRENTS AND RIVERS. 129 enormous volume of water is then precipitated with extreme vio- lence, and nothing can withstand the combined effects of its mass and rapidity. All is overturned, and the most solid rocks, if they project, in the'least, across the direction of the current, are instantly torn away, broken, and transported to great distances. The clear- ing is so complete, at the origin of the current, and in the narrow passages where the slope is rapid, that the exposed rock seems to have been cut by the hand of man. 13. Mud-torrents, from one cause or another, are also formed, which are not less terrible in their ravages. It sometimes happens, as in Ireland, that turf-beds placed on a slight declivity, after being swelled, more or less arched by retaining rain-water beneath them, cannot resist the first heavy shower, and are set in motion. They run then, in spite of the consistence of the mud, and the gentleness of the descent, with prodigious rapidity, and sweep everything they meet. Under other circumstances, the rain-waters soak in loose, argilla'ceons substances, accumulate in the* midst of them, and, at a certain moment, the dykes of the reservoir give way, and a torrent of thick mud, filled with fragments of rock and even blocks, suspended in the viscid mass, is formed, and rushes with fearful rapidity, overturning everything, and cutting deep ravines. 14. Slopes of torrents and rivers. The disastrous effects of torrents are in proportion to the descent on which they move ; but it does not necessarily follow that their bed must have a very con- siderable inclination. The most rapid torrents, forming a continu- ous bed and carrying rocks a half-yard in diameter, have a descent of only one or two degrees, and many rivers flow very swiftly on a much less slope a descent of from three to four minutes (sixty to a degree) is about the limit for navigable rivers. 15. Rolled flints, or pebbles. In the ravages produced, by water-currents, the debris torn from mountains are transported to a greater or less distance, accordingly as the inclination of the soil permits the current to maintain its force for more or less conside- rable distances ; but in proportion as the slopes diminish, the swift- ness decreases, and the larger blocks successively remain behind, at the bottom of the valley, and then those of smaller size, and suc- cessively the sand and mud, which are often carried enormous dis- tances. In this rolling of different substances, the blocks and frag- ments sinking during their transportation, rubbing against each other and against the soil, gradually lose their prominences and angles, and in the end become completely rounded, forming what are termed rolled flints, which may be more or less voluminous. 1 3. How are mud-torrents formed ? What are their effects ? 14. Upon what do the effects of torrents depend ? What is the rate of the slope of beds of rivers that are navigable? 15. How are rolled flints and pebbles produced? W j What is sand ? ^ v OF THE UNIVERSITY 130 TRANSPORTATION BY ICE AND GLACIERS. All the lower part of torrents, where the soil is sufficiently flattened, or the enkrgement of the valley permits the waters to expand, diminishing their depth, and consequently their rapidity, is gene- rally found covered with these flints, which are sometimes accumu- lated in immense quantities, and through which, in its ordinary course, the stream meanders in different ways, in a bed it forms and often changes. Rivers and lakes into which torrents empty, and where they consequently lose their swiftness, are often loaded with these flints ; and this is the cause of the constant elevation of the bed of the river Po (see page 15). Gravel and -saw/, which are merely small flints, the mud which results from their friction, and the earthy particles removed, are always transported far, either immediately into lakes, or seas, or rivers, which deposit them on their banks, and especially at their mouths, which they more or less obstruct. 16. Rolled flints, or pebbles, are also formed by the action of the waves on fallen 'rocks. In this way, on the coasts of France and England, the silex, or flints of the chnlk, are rounded, by being rubbed against each other, and constitute considerable banks of pebbles or shingle. Something similar must have taken place at points now far inland, where we find blocks round and smooth, at a short distance from rocks from which they were evidently de- tached. 17. Transportation by ice and glaciers. On the shores of northern seas, the ice envelopes blocks and masses of rock, which, at the breaking up, are floated away on ice-cakes in all directions, and deposited here and there, wherever they may ground, or fall to the bottom of the sea. In this way, in Canada, Greenland, and on the coasts of Nova Zembla, &c., very voluminous blocks are transported from one place to another, and often to very conside- rabFe distances from the point of departure. There is no doubt that many small debris, embedded in the ice, are transported in the same way, and form adventitious deposits of more or less extent. 18. Glaciers, that is, beds of ice occupying the high valleys of lofty mountain chains, are also very remarkable means of trans- portation. Various circumstances (their great weight chiefly) keep these deposits in constant, though very slow motion, from half an inch to an inch an hour, descending along the slopes on \vhich they rest ; now, the surface of these glaciers is found to be covered with fragments and blocks which have fallen from the surrounding mountains, and the whole is conveyed from the upper to the lower part ; and blocks, often of enormous size, are carried 16. Are rolled flints, or pebbles, produced by running water exclusively? What is shingle ? 17. How are rocks transported by ice ? 18. What are glaciers? At what rate do they move? What are moraines ? ACTION OF THE WAVES AND OF TIDES. 131 without friction to considerable distances from their place of origin. These debris, from several causes, always accumulate on the late- ral parts of the glacier, against the side of the valley, and fre- quently in the middle also, from other valleys emptying laterally into it, from which result long, slender hills, designated under the term moraines. All these debris, having reached the inferior ex- tremity of the glacier, tumble into the valley on its slope, and form at its foot other moraines often of considerable height. If, after having increased for a certain time in consequence of a series of cold summers, the glacier diminishes again by a succession of warm, prolonged summers, the moraines of different kinds, aban- doned by the ice, are left on the soil ; some form dykes, of more or less height, at the bottom and across the valley, and others long lines on the flanks of the valley, at a greater or less elevation. 19. It must be borne in mind that the slopes on which glaciers move are always much greater than those of rivers, and that they never descend at an angle of less than three degrees. This must also be the minimum slope of masses of debris resting on the sides of the valley, in consequence of the rapid melting of the glacier. Thus we have a means of distinguishing the remains of lateral moraines from deposits which may have been made by water-cur- rents, the slopes of which are very much less. 2i). Striae, channels, polishing of rocks. Among the effects produced by the motion of a glacier loaded with debris, and moving slowly over the exposed face of a rock, is a rubbing, wearing, and polishing of the surface which is passed over. The angles of the rocks passed over are rounded ; deep undulating grooves, nearly parallel and longitudinal, are cut in the surface, and the polished surface of the rock passed over is scratched with fine striae, even when it is of the hardest quartz. These effects are well known to be produced by modern glaciers. 21. Action of (he waves ami of fides. Waves exert an enor- mous power, particularly where rocks are abrupt and directly ex- posed to the open sea. The shock is sometimes so great that the earth trembles beneath the feet; great blocks of stone are torn up and carried far inland, pushed up against the inclination of the shore, sometimes thrown up vertically on projecting points, where they afterwards roll about like small pebbles : heavy banks of sand and of shingle are often removed, and entire countries have been in a moment destroyed. Chronology and tradition of maritime countries furnish numerous in- stances of successive changes, of instantaneous disasters which have oc- curred in a great many localities. Immense ones have taken place, and every day new ones occur on low, sandy coasts, bordering the sea, in many 19. What is the least slope or angle at which glaciers move ? 20. What effects are produced on rocks by the movement of glaciers loaded with debris ? 21. What is the effect of the action of waves ? 132 ACTION OF THE WAVES AND OF TIDES. parts of the world : we have famous examples from the mouths of the Scheld to the canal of Jutland, where the Bies-Bosch, the Harlem sea, the Zuyder- Zee, the Dollart, have been produced in the extraordinary irruptions of the ocean ; where numerous changes have taken place in the islands, from the Texel to the mouths of the Elbe, in the windings of Lymfiord, or on the coasts of the Cattegat and of the Baltic : immense cuts, bays, and deep gulfs are formed during tempests, and these are still daily forming by the ordinary action of the waves, which sometimes carry away banks of sand, and sometimes destroy the dykes they had already formed. 22. The action of waves is not confined to moveable soils, but takes place on the most solid rocks ; and hence those daily modi- fications in the enormous precipices found on the coasts of France, England, and almost all parts of the world. The more abrupt the coast, the more it is exposed to denudation from the waves, because directly breaking them, the shock is felt in all its force. On flat coasts, on the contrary, the wave meeting with no obstacle, ad- vances as long as its force lasts, and until its rapidity is sensibly- lost ; and it carries up in sand and pebbles much more than it destroys, even on the most moveable soils. The natural disposi- tion of solid beds is sometimes opposed, and at others favourable to the action of waves; it is opposed when the beds, being uniform and homogeneous, incline towards the sea ; because the return of the wave along the slope or ta'lus diminishes the action of the suc- ceeding wave, the remaining force of which is spent in merely ascending the plane: the waters are spattered only by the crevices and fissures that may exist in the rock. But the same is not the case when the soil presents an escarpment to the action of the waters (figs. 211, 212): the lower parts, continually attacked by Fig. 211. Fig. 212. Action of waves on abrupt rocks. reiterated shocks of waves, which nothing contributes to diminish, are degraded and excavated successively, and with a rapidity in proportion to the facility with which the substance is disaggregated ; the upper beds being soon undermined, are not long in being pre- cipitated into the sea. In this way considerable portions of coast have been overturned at different times, promontories have disap- 22. Are all coasts equally subject to the action of waves. What circum- stances diminish the effects of the action of waves ? ACTION OF THE WAVES AND OF TIDES. 133 peared, and others have been cut off and separated from the main land. These effects are more rapid in places where a deep sea swallows up the detached blocks, or i^ those where the force of the waves is sufficiently powerful to break up the debris, and wear them one against the other and successively remove them, so that the foot of the escarpment always remains bare. 23. When masses of debris falling from precipices are not im- mediately removed, a natural rampart is formed against the action of the waves, which break before reaching the foot of the escarp- ment (Jig- 213); then it is only in a long time that the debris are worn, rounded, and carried away little by little, depending on the solidity of the rocks of which they are formed. These natural ramparts are imitated as much as possible by piling rocks before the ta'lus we wish to preserve on Fig. 213. Accumulation of debris sea-coasts or river banks. opposing the action of waves. 24. To the action of waves must be attributed certain excava- tions frequently found, on a level with the sea, in calcareous preci- pices, as well, perhaps, as the arches of greater or less height which traverse certain promontories. Nevertheless, this action does not immediately produce great results, except on matters easily disaggregated, such as chalk, clay, and arena'ceous sub- stances, and it is infinitely slow on more compact and harder sub- stances : in fact, there are points where no effect whatever has been produced within historic times. The erosive power of water does not explain all these facts, nor even the impetuous force of waves ; the soils on which this power is exerted are cracked in all directions, either by previous action, or at the moment of earth- quakes, accompanied by violent agitations of the sea, and it is then they yield to the combined forces to which they are exposed. By this means we can account for isolated rocks, for islands in the vicinity of continents, for those great gaps through which the sea finds passage, for those groups of split rocks which form shoals in the midst of the sea, and for all those severings so common and varied on the coasts of France and England, in numerous islands that extend towards the North Sea, and in a great many localities (Jigs. 214, 215). 25. Deposits of detritus formed by wafers. Although waters continually degrade certain parts of the globe, they create in a measure new deposits proportioned to those they remove. Tor- 23. What circumstance protects coasts from the action of waves ? 24. What effects are attributable to the action of waves ? 25. How are deposits formed from water ? 12 134 ACTION OF THE WAVES AND OF TIDES. . 214. Fig. 215. Examples of rocks eroded and shaped by waters. rents, after having torn away blocks and fragments of rocks, re- duced them to rolled flints or pebbles, and carried them to a greater or less distance, deposit them, in proportion as the swiftness of the waters diminishes, in the inferior parts of valleys they run through, or at their confluence with rivers, or in lakes. Hence the masses of debris, sometimes immense, the coarse parts of which are ce- mented by the mud, they deposit at the same time. 26. Great rivers, running through valleys of little inclination, generally leave behind the coarser parts they have received, and only bear forward those whose weight is in relation to their force ; but as their slope diminishes more and more, becoming almost in- sensible towards the end of their course, they deposit the matters they carry, and in this way generally elevate their bed; and finally they even bar up their passage, and divide into several branches, each of which cuts its way through sands. Rivers have in this manner covered flat countries through which they pass with sand to a considerable depth and extent. In great freshets these sands are often taken up again, transported from one point to another, forming islands in the middle of the river, or alluvions on one of its banks, while the other is hollowed out. In rivers, lakes, or seas, these deposits become most remarkable. There, if the current is not rapid enough to carry the debris to a distance, in spite of the opposition of tranquil waters, or if the waves have not sufficient force to remove the sands and mud which have been deposited; they form deltas at the mouths of certain rivers (see page 16). 27. The sea itself, which in so many places has made breaches in the main land, in others, heaves up and accumulates enormous quantities of pebbles, formed by the trituration of rocks fallen from precipices, or masses of sand and mud produced by the waves, or 26. What are the effects of deposits from rivers ? 27. What are the effects of deposits from the sea ? ACTION OF THE WAVES AND OF THE TIDES. 135 brought down by rivers. In this way banks and beaches, of greater or less extent, are formed on coasts, the finer parts of which, car- ried inland by the wind, form dunes (see page 125). There are many places where, accumulations of this kind are daily formed, and many points of coast have been invaded by deposits from the sea from remotest times : sometimes, by a single irruption, entire kingdoms have been covered by sand, and fertile countries changed to arid plains, either in extraordinary tides, or in tempests, or by the sudden displacement of waters consequent on earthquakes. Low countries, exposed to these alluvions, daily grow at the .ex- pense of the waters, and, at certain points, this growth has been estimated at several yards a year. Bays and ports have been filled up in this way ; buildings and towns, formerly situated on the sea- shore, are now far from it ; lakes have been transformed into marshes, marshes into solid land, and islands joined to the main by sands deposited around them. The sea, in some instances, contri- butes to the growth of deltas. 28. Torrents and rivers transport not only mineral debris, but also organic remains, immense masses of plants, detached from ravines, or by falls. Here and there great masses of materials are formed, especially in rivers which are bordered by immense forests. Great deposits of debris of this kind are formed in the Mississippi and its tributaries ; they there form immense rafts of trunks of trees, interlaced, which are stopped here and there by the sands, and finally are buried under the enormous alluvions daily deposited. The mass of plants that the river carries is so considerable, that it has been estimated at several thousands of cubic yards per hour. 29. Currents of the sea also often transport immense masses of various vegetables, marine plants, and organic debris of every kind, and from all climates, which are here and there deposited in the bays these currents meet in their course. This is especially the case as regards the great Atlantic current, the Gulf Stream, the strongest and most considerable of all, which extends along the coast of North America to the icy regions, where the polar currents accumulate these debris with those of other parts of the world. We cannot doubt, on reflecting on the quantity of debris borne by the waters, that Jakes which receive rivers are filled up, little by little, by the matters daily brought into them ; this is evident, in some places, where marshes and considerable alluvions are thus formed. The same must be true of the bottom of the sea, where all waters finally come ; it is easy to con- ceive there must be daily formed considerable dq>osits of all the substances which are carried there, as well as of those washed away by the waves, and of all the remains of animals which perish in this vast abyss. 30. Deposits of substances held in solution. Waters degrade 28. Are all the materials, transported by waters, of a mineral origin ? How are the rafts in the Mississippi formed ? 29. What effects are due to currents of the sea ? 136 DEPOSITS OF SUBSTANCES HELD IN SOLUTION. and carry away different substances ; some they also dissolve, and afterwards deposit them, by evaporation, in form of solid sediments, which are sometimes more or Jess crystalline. To the infiltration of these waters, for example, is due all kinds of stala'ctites (from the Greek stalasso, I drop), which form in various subterraneous cavities, and especially large in caverns found in calcareous coun- tries. Certain waters are rich in dissolved materials, and suffi- ciently abundant to give rise to extensive deposits on the surface of the earth. Those particularly, which, by carbonic acid, hold a great quantity of carbonate of lime in solution, and which, from abundant or numerous springs, give origin to rivulets and even lakes, at the bottom of which is daily formed what is called traver- tin or calcareous tufa. These waters are met almost everywhere, in calcareous regions. Scattered over a flat country, or on the slope of a valley, these waters incrust the plants growing there, and, from these agglomerated and superposed incrustations are formed considerable rocks, the mass of which is consolidated by waters which percolate the interstices they meet, and render the whole solid and uniform. When these waters flow over slopes free from vegetation, they deposit thin and successive layers, following the undulations, the whole forming compact masses which daily grow in thickness. In lakes into which waters of this kind flow, hori- zontal beds of solid calcareous matter are formed, which are often filled with fluviatile, and even terrestrial shells, daily brought into it. 31. Sands washed up by waves, either in fresh-water lakes or seas, are daily consolidated by waters more or less charged with carbonate of lime. Examples of this kind are seen in the sands of lake Superior, in those of the gulf of Messina, at several points on the coasts of England, of the West-India islands, chiefly at Guadaloupe, New Holland, &c. These arena'ceous substances often become sufficiently solid for building purposes. 32. Sili'cious deposits. A great many mineral waters, particu- larly those which are warm or hot, contain, besides carbonate of lime, a certain quantity of silex (from the Greek chalis, a pebble) ; on this account many calcareous tu'fas are more or less silicious. But there are springs in which the silex is sufficiently abundant to form considerable deposits of hydrated sili'cious deposits, some- limes nearly pure, and sometimes mingled with other substances. The tu'fas of the geyser in Iceland are deposited for nearly a quarter of a league round the spring, three-quarters of a yard thick. One of these geysers (a word which according to some means spouting, and furious, according to others) spout? up every half 30. How do waters form deposits from matter held in solution 1 What are stala'ctites? 31. By what means are sands consolidated? 32. How are sili'cious deposits formed ? What is a geyser ? STRUCTURE OF SEDIMENTARY DEPOSITS. 137 hour a column of boiling water, eighteen feet in diameter and one hundred and fifty feet high. Analogous springs of hot water exist in the Rocky mountains, and in India, as well as in Saint Michael's (Azores), where the sili'cious deposits are found in thin beds, alter- nating with argilla'ceous substances which the same waters bring from the interior of the earth. Organic remains, particularly vege- table, are found in all, some of which have passed into the sili'cious slate, while others have disappeared, leaving only their impressions behind. 33. Structure of sedimentary deposits. Effects of land-falls. If we examine deposits of de'tritus, formed at the foot of mountains by the daily destruction of its rocks, it will be seen their slopes are very variable, the greatest not exceeding an angle of forty-five degrees, and the least being seldom less than twenty degrees ; the variations between these limits are found to be in relation to the size, the form of the fragments, and circumstances of the fall, rather than to the nature of the substances themselves. Hence it is, if, at different successive fallings, there are variations in the form of the fragments and in the circumstances of the fall, there will be an accumulation of deposits, the slopes of which will be succes- sively less, and which, in ravines ^ excavated by water, will have nearly the arrrangement repre- ^ sented, a, b, c, d, e, (fig. 210), | where each additional deposit is II thicker at its base than at the upper part. It is evident the same thing may take place in stagnant waters ; whence it fol- lows that from the fall of a river _. ~ ir into a lake with steep banks, a ** 216.- 7W. from fatting. very considerable ta'lus may be formed, and from different acces- sions or growths, which bring materials of different form and size, deposits similar to those just mentioned may be produced. 34. Effects of transport. If in some places, even under water, beds may be deposited at an inclination of from twenty to forty-five degrees, it must not be inferred that the same is true of extensive deposits, where running waters, if unimpeded, may force the debris in every direction. Here the inclination of the ta'lus is much less ; they never attain even the minimum angle of slopes farmed of fallen matter, and never reach even ten or twelve degrees, only in exceptional cases of very rapid torrents, or rather of true cascades, at the place where they fall into a transverse valley, and where there is as much matter tumbled down as transported. The beds of the most rapid rivers are much less inclined, and the successive 33. What is the structure of deposits from land-falls ? 34. Is the angle or slope of a ta'lus always the same ? 12* 138 EFFECTS OF TRANSPORT. deposits are for the most part nearly horizontal. Gravel and sand which the waves wash upon coasts, are also deposited at very small angles, and slopes of ten degrees are exceptions, even in localities exposed to the strongest billows ; most frequently they are much less, and nearly horizontal. 35. It frequently happens, during the drift or transportation of matters by currents, and by freshets in rivers, when the bottom is disturbed, that effects analogous to those of sea-winds on dunes are produced. Ridges are formed across the current ; various mat- ters, pushed over these initial hillocks, accumulate behind them, forming a ta'lus of successive fallings, which impart the structure represented in fig. 217. If the river change its course, the undu- lated surface of the first deposit is soon levelled, and quiet deposits are formed above (Jig- 218), from which the preceding may be distinguished by the particular structure attributable to the circum- stances of its formation. Fig. 217. Fig. 218. Structure produced by the transportation of materials. These effects, resulting from a mixture of rapid and tranquil deposits (that is, deposits formed from rapid currents and tranquil waters), are very clearly seen in alluvions on river banks, and par- ticularly in deltas, which terminate their course when the waters have excavated some ravine near by. We then perceive that the mass of the deposit is formed of horizontal layers, having a surface more or less undulated (Jig. 219), which are distinguished from Fig. 219. Structure of alluvions in rivers. each other by the size of the component parts, by the colour, by the structure produced by rapid accumulation, either by pushing forward the matters in the direction of the ordinary current, as in the deposits a and , or in a different direction, as in the deposit c, which indicate counter-currents formed at one time or another. Often there are particular masses, d, formed here and there, which ordinarily consist of coarser gravel, or of different organic debris. 35. What effects result from transportation or drift ? EFFECTS OF OSCILLATORY MOTION. 139 36. Effects of oscillatory motion. Great masses of water, sub- ject, like the sea, to undulalory motion, present another order of facts ; not only are suspended substances deposited there in hori- zontal beds, as a more weighty fluid would do, but the slightest agitation does not permit any material particle to be solidly fixed on planes of the least inclination, but tends, on the contrary, to de- stroy all inequalities of the bottom. It is impossible to ascertain positively these effects at the bottom of the sea ; but the immense number of soundings, taken in all parts of the ocean by navigators, show that all moving bottoms have very slight inclination ; that slopes, at an angle of half a degree, are rare, and that all above this are exceptions : hence it follows, that in great masses of water, beds formed by successive deposits must be entirely horizontal. This fact is most clearly exhibited in certain lakes, which have been entirely or in part dried up, where alternations of beds, of every kind, are seen to be perfectly horizontal ; lakes Superior and Huron furnish examples of this kind. 3^. This disposition of various matters deposited from water, bed by bed, at the bottom of rivers, lakes, marshes, is termed strati- fication ; the deposits themselves are said to be stratified. This circumstance eminently distinguishes deposits formed by water, from those produced by igneous fusion, which are most frequently massive, or irregularly divided. 38. Nature of deposits organic remains. Beds of alluvium are formed of rolled flints, gravel, and sand, as well as of various kinds of mud, analogous to matter called clay or argil. They are more or less consolidated, as much by their own weight, as by waters charged with carbonate of lime, or various matters which may penetrate them. In lakes, we see calca'reous and ar- gilla'ceous marls, which have the property of hardening in the air, as has been observed in certain half-dried lakes in Scotland, in modern building-stone found in Hungary, and in lakes Superior and Huron. Similar formations doubtlessly occur in the sea, as waters are sufficiently calci'ferous to consolidate the sands thrown on its coasts ; and the nature of upheaved deposits, in many places, leave no uncertainty in this respect. These deposits are frequently filled- with remains of all the organized creatures now living 1 on the surface of the globe. In river alluvium we find remains of fluviatile shells that still live in the same localities, or land shells, such as various snails, brought thither by rivulets ; there are branches and trunks of trees, masses of plants, more or less changed, sometimes partly bitumenized, bones of terrestrial or aquatic animals, rarely human bones, but frequently the remains of art, such as fragments of brick and pottery, &c. 36. What is the position of strata formed under the influence of undula- tory motion of water? 37. What is meant by stratification ? 38. Of what do beds of alluvium consist ? 140 CORAL REEFS. Alluvions formed by the sea are very similar ; they contain marine debris of every kind, sometimes alone and sometimes mingled with fluviatile and terrestrial debris, brought into it by rivers. Debris of* human industry, an. chors, boats, &c., are frequent, and even man's remains exist ; not only in cemeteries of villages that have been overwhelmed by sands, but also among the debris cast up by the sea, as at Guadaloupe, where human bones are found in a sand consolidated by a calca'reous tu'fa, and mingled with debris of human art. In deltas formed partly of fresh water and partly by the sea, we find alternate layers, the one filled with marine debris, and the others by those of fresh water; but, under other circumstances, all these remains are found indiscriminately mingled. Argilla'ceous, marly, or calca'reous deposits, in lakes, contain the remains of fluviatile and terrestrial mollusks, similar to those now existing in the same regions. Remains of fishes and mammals are also occasionally found. There is no doubt deposits formed in the sea also contain remains of the numerous animals that daily perish. We learn from soundings that the bottom of the sea, in many places, is covered by shells, broken or entire, fragments of madrepore, echinidae, &c., sometimes mingled with sand, sometimes by themselves, constituting considerable banks in progress of formation and consolidation. 39. Coral reefs. Formations of stony polypa'ria, agglomerated with each other, often of great extent, are thus named ; in inter- tropical regions they constitute a great number of islands, on a level with the sea, or submarine banks, the mass of which rises more and more. It is scarcely twenty years since it was supposed that the little animals \vhich form these deposits, by a calcareous exu- dation, had the faculty of living at great depths in the ocean ; it was thought they began their dwelling, and gradually augmented the mass, until it formed immense mountains, the summits of which constituted the reefs, and that they gave origin to most of the large islands formed in those regions. These microscopic creatures, it was said, tended thus to fill up the ocean, and were preparing prodigious changes on the surface of the globe. But all this exaggeration has disappeared, the observations of MM. Q,uoi and Gaimard having shown, that the species which contribute most to the formation of reefs,^uch as caryophy'llisc (Jig. 220), mean- dri'nse (Jig. 221), and particularly the as'lrcsc (fig. 222), which sometimes cover immense spaces, and various madrepores (Jig- 223), cannot exist except at moderate depths, and ten or twelve yards below the surface no trace of them is to be found. It is, then, on pre-existing rocks, already elevated under w r ater, often very steep on the sides, as soundings show, that these animals begin to build ; and from this they afterwards accumulate their solid product to the level of the sea, where their last generations perish. They cannot, then, fill up the ocean ; but the incrusta- tions they form are not the less important, since they are sometimes ten or twelve yards thick, extending over immense spaces, and these are found in a great many places in all seas comprehended 39. In what parts of the world do we find coral reefs ? How are they formed ? At what depths do polypa'ria live ? CORAL REEFS. Ill Fig. 220. Caryophy'llia fastigiata. Fig. 223. Madrcpo'ra murica'la. Fig. 221. Meandri'na labyri'nthica. Fig. 222. Astrea viridis. between the tropics. They crown most submarine mountains, and cover thousands of square leagues, distributed among thousands of islands and reefs. 40. These sa'xigenous polypa'ria, attached to every kind of rock, surround most large islands with their products, forming around them a kind of rampart, separated frequently by deep water. In other instances they form islets, detached or grouped in different ways, and they are, when there are breakers, the more dangerous, because they are not seen before being cast upon them, and because the depth of water is so great as not to afford anchorage. It is these deposits which render navigation so difficult in certain parts of the South Sea, and cause so many deplorable losses by shipwreck. Some of the forms assumed by these deposits at the surface of the sea are particularly remarkable, and are not yet entirely explained ; sometimes these reefs are completely annular 40. What is the form of coral islands ? 142 CORAL ISLANDS. Fig. 224. Coral island in the Pacific Ocean. (fig. 224), with a lake in the centre, enclosed on all sides ; some- times they form broken circles, having- one or more openings through which the centre may be reached ; again, they are in groups of islands, arranged in a circle, and frequently there are several in a series. In these internal seas the water is often very deep but sometimes very shallow, and an immense number of polypa'ria are developed, which sooner or later fill up the space. It appears evident that these circular reefs are the edges of different upheaved craters, upon which the polyps have established them- selves ; this is inferred from the volcanic nature of most islands in the Pacific, and from the manner in \vhich submarine eruptions sometimes take place. Nevertheless, this explanation is not re- ceived as satisfactory in respect to many reefs of the kind, and particularly those which constitute -the Maldives and Lakadives, groups in the Indian Ocean. The great number of circular groups found in certain localities, and the immense expanse which we must suppose craters of elevation to have in other places, are facts urged in objection to the explanation. Around cor.il reefs, as well as in the lakes they enclose, soft and white mud of a calcareous nature, analogous to chalk, has been observed, which has sometimes been referred to the disintegration of madrepores, and some- times to dejections of worm's which pierce the polypa'ria, or to those of fishes which feed on them. In many places in the South Seas this mud seems to constitute considerable deposits. 41. When a reef has reached the level of the water, the sea often covers it with debris of every kind, on which vegetation is afterwards developed. Most low islands in the Pacific have been produced in this way, all of which rest on masses of polypa'ria. A great many other* islands have sprung up on their coasts in the me way ; and there are many which will sooner or later grow same 41. How are coral islands formed ? PEAT, OR TURF BOG. 143 up in the same manner, for now, at low tide, we may walk over reefs extending half a league from the shore. But one very im- portant circumstance is, that in many places we find precisely simi- lar deposits, composed of the same species of madrepores, in the interior of land at an elevation of from 200 to 300 ya-rds ; this is seen at Timor, where the deposits are ten or twelve yards thick ; at New Holland, Van Diemen's Land, at the Marian Islands, Sandwich Islands, &c., where they rest on argilla'ceous schist, sandstone, limestone, volcanic products, &c. ;. in the Isle of France a similar bank, four yards thick, is found placed between two cur- rents of lava. The existence of these deposits in such situations evidently indicates that all these islands have been upheaved from the bosom of the waters, and often at several different periods, for we often find banks of coral at different levels. 42. Peat, or Turf Bog. There are daily formed, in different excavations of Jihe surface, in valleys of gentle slope, in low and marshy situations, deposits of vegetable matter, the decomposition of which furnishes a combustible called turf or peat, and the mass bears the name of peat-bog. These deposits are formed only under particular circumstances : they are seen only in places where stagnant waters constantly exist, and only in shallow depths ; the presence of light is necessary to secure vegetation, to which peat chiefly owes its origin. The production of peat, to which all aquatic plants contribute, is princi- pally owing, however, to those which are always submerged, and which multiply rapidly; their debris form the principal paste that envelopes all the others, and probably contributes to their decomposition. A number of ter- restrial plants also, brought to these bogs by brooks, contribute to the forma- tion. Frequently large trees are found buried in the mass, particularly in the lower parts, where they accumulate on sands and clays which form the bottom. Often they are seen broken and fallen near the root, which is found attached to the bottom of the bog. In some instances these debris are very numerous, and seem to indicate that entire forests must have been buried on the spot where they grew, before the formation of peat. The plants found in these situations all belong to existing species ; they are resinous trees, oaks, birch, &c. Remains of mammals are often found in peat.-bogs, such as the bones of oxen, the horns of deer, tusks of wild-boars, &c. 43. Peat-bogs rest on every variety of soil, sometimes even on crystalline rocks ; most generally, however, they overlie deposits of sand or clay, and sometimes the rolled flints of the country. There are places where accumulated debris of plants form but a single mass, of greater or less thickness", more compact and blacker at the lower part than in subsequently formed parts of it ; there are other places where the different beds are separated by sedi- mentary deposits of alluvium. These are formed of sands, clays, calca'reous or argilla'ceous marls, often containing fresh-water shells in great quantity. Sometimes the surface of the deposit remains 42. What are peat-bogs ? Of what do they consist? 43. On what do peat-bogs rest ? 144 CONSEQUENCES OF CENTRAL HEAT. covered by water, and at others it is covered by a luxuriant vege- tation. 44. Peat-bogs are numerous in different parts of the world ; they occupy basins or depressions in the soil at different elevations, even in the Alps. One-tenth of the whole surface of Ireland is said to be covered by peat-bog. In the Great Dismal Swamp of Virginia and North Carolina, there is a deposit of peat from ten to fifteen feet in thickness. LESSON VIII. EXPLANATION OF VARIOUS PHENOMENA. Consequences of Central Heat First effect of cooling Warm Springs Deposits referable to Sediment Fresh-water Deposits Fossils of Ma- rine Deposits Fossils of Carbona'ceous Deposits. EFFECTS ATTRIBUTABLE TO UPHEAVAL AND SUBSIDENCE. Shell Deposits and raised Beaches Submarine Forests Tracks of Quadrupeds and Birds Dislocation of Strata Faults Cra- te 1 riform arrangement of Strata Valleys of Elevation Up- heaval without Dislocation Distortion of Strata Origin of Valleys Valleys from Dislocation, from Subsidence, from Folding or Plaiting, from Erosion or Denudation Origin of Caverns. Having established the fact of a central heat capable of keeping- every, thing in a state of fusion, at a short distance beneath the surface we inhabit; having shown the actual effects of earthquakes and of volcanic action ; having pointed out those which waters produce, both by denudation, or de- gradation, and the formation of new deposits, it is natural to attempt, by reference to these effects, the explanation of all geological phenomena which have occurred on the surface of the globe from the first moment of its exist- encc. The causes now in action are the same as those which have acted through all time; but doubtlessly they were more energetic at certain epochs than present observation shows. ' 1. CONSEQUENCES OF CENTRAL HEAT. The complete fluidity of the globe gave rise to its ellipsoidal form : the heat so long pre- served, and still existing beneath the cooled pellicle or crust, has produced, and is now producing a great number of phenomena. The temperature of the surface is nearly stationary, and has not varied since the period of records, and will not probably change. But before reaching this state, which probably required thousands 44. Where are peat-bogs found ? 1 . What influence is central heat supposed to exercise over the form of the globe ? Had the central heat any influence on climate ? How do you account for the fossils of tropical plants and animals being found in northern regions ? CONSEQUENCES OF CENTRAL HEAT. 145 of years, the surface of the earth must have passed through every degree of heat, from the state of fusion in which the centre still is to its present degree of cold ; consequently, there was a time when the temperature of the earth was such as to do away with differences of climate, or an atmosphere of vapour, which, hy overcoming radia- tion, diminished the rigour of winter. Then vegetation, and life generally, could be as equally maintained in all latitudes as in a hot-house. From this it follows, that plants and animals now found only between^the tropics could then live anywhere, even under the poles, which were not then encumbered in ice. It is therefore not astonishing that we should find the remains of these various creatures buried nearly on the spot where they lived, in countries which are now the coldest in the world, and in which it would be impossible for them to live at the present time. There is in England, on the island of Portland, and at several places on the continent, intercalated in other deposits, a bed of black matter, called dirt-bed, and small argilla'ceous beds, in which, among a great many vege- table remains, bedded and scattered, are various plants in their place of growth (fig. 225), the roots "of which extend into the fissures of the calca- reous soil beneath. There- fore, there must have been a vegetable soil, on which all the plants now buried in the earth then grew. But all the species found in this bed belong to genera, such cycas and zamia, which now live only in the tropics, and the remains of animals Fi S- ^.Portland dirt-led. also belonged to the same zone ; consequently the mean temperature at the time of this formation was very different from what it is now in England. Most of the coal deposits of Europe lead to a similar conclusion. Entire trees with their roots, many of them still erect, are found, as in the mine of Treuil, near St. Etienne (Jig. 226), in the mines of Anzin (North) in Eng- land, in Scotland, &.C., which seem to indicate, as in peat-bogs, plants that grew very near the places where they are now found. It is evident from the perfect preservation of the most delicate parts of plants, the manner in which the leaves are extended on schists, that these remains could not have been carried far. All the remains of plants found in these deposits belong to the equisita'ceae, lofty ferns, to the lycopodea'ceae, &c., and cannot be compared with those now existing in the tropics; consequently, the climate of Europe must have been then very different from what it is at present. We find, in the latitudes of Europe, certain beds containing the remains of intertropieal plants, but we also find above them considerable deposits in which are dicotyle'donous plants of the present time. The formation of the Inst deposits, then, must have taken place long after the first; and it is pro- bable that between the epochs, a period of time elapsed, sufficient for cooling the surface of our planet. Madrepores of reefs, which now do not exist beyond the tropics, then evi- dently extended to the polar circle. In fact, the limestones of different periods contain a great number, and frequently show that reefs existed corn- parable to those of our days. Facts show that the limits of these banks of zo'ophytes have retrograded, from the period of the deposit of the oldest 13 146 CONSEQUENCES OF CENTRAL HEAT. Fig, 226. Vertical stems in the mine of Treuil, St. Elie.nnc. limestones to that of the chalk, after which they suddenly retired to their present limits ; in other words, the climate of Europe has grown successively colder. First effect of cooling. The idea of complete fusion, and of cooling, which the observation of the phenomena forcibly leads us to admit, also leads us to conceive what must have taken place on the first consolidation of the globe's surface. The first solid pellicle formed underwent, from cooling, more or less contraction, and on this account must have broken in all directions, from the action of the melted matter it covered, swimming in pieces on its surface, and uniting anew more or less irregularly, to be again broken. But assuming greater consistence, and pressing more and more on the liquid part, this must have gushed up through the rents, then more rare, and formed above the crust projecting ridges, of more or less extent, which increased in height in proportion as the resistance of the. crust became greater, and caused stronger and stronger reaction. Hence the first rugosities, the first ridges formed on the surface of the globe, which possibly afforded the first hold for the action of water, the precipitation of which took place, without doubt, long before the temperature of the teirostrial crust had descended to 212 of Fahrenheit's thermometer, in consequence of the pressure exerted by the vapour then diffused in the air. From that moment waves produced debris, and arena'ceous matters, and sediments began to form. Probably the water, at a high temperature, charged with the principles disengaged from the solidified masses, like lava of the present time, attacked the stony matters, disintegrated and dissolved them, and subsequently formed chemical deposits, or consolidated the debris. In fact, we find deposit? formed of fragments, of rolled flints and of sands, in the most ancient layers yet exa- mined, and before meeting with organic remains. All the solid layers formed beneath the first pellicle, like it, being sub- jetted to the law" of contraction from cooling, must have been filled with cracks in all directions ; therefore the whole terrestrial crust, thus formed, could not have been as solid as might be at first imagined : it could not WARM SPRINGS. 147 resist, so successfully as might be thought, the internal actions, which, meet- ing no obstacle in the sedimentary deposits subsequently formed, must have dislocated them in all ways. In fact, there is no deposit on the surface of the globe, either sedimentary or crystalline, which is not found to be cracked in all directions ; even on the upper surface, most rocks are broken in small fragments, to a considerable depth. While the crust of the earth was gradually cooling, things must have passed nearly as we have stated ; but, after the temperature hud become stationary, as it is now, it could not' have been the same : the superficial pellicle docs not contract, because it does not grow sensibly cooler. Never- theless, the interior mass is still cooling more and more, although with ex- treme slowness*, and consequently diminishing in volume ; now, the fluid part tending to drag with it that which covers it, and which becomes suc- cessively too large, this must contract on itself, and ridge the surface by dis- locations through its whole thickness. This may take place tranquilly, for some time ; but, at certain moments, the effect cannot fail to take place quickly, and hence the sudden catastrophes experienced on the earth's sur- face. All observations, in accordance with geometrical considerations, show that these ridges and these dislocations arc formed according to the great circle of the sphere, and extend over the half of its circumference. 2. Warm springs. The different degrees of temperature of warm springs are referable to the central heat, which is communi- cated through fissures of greater or less profundity. The waters come to the surface with the temperature of the point whence they started, and, it is known, that at the depth of about 3280 yards, they boil. Now it may be readily conceived how, during earthquakes, new hot springs may appear in a country, and how those that existed there may be lost ; in the first instance, all that is required is a fissure, to establish a communication between the surface and a proper depth ; and, for the second, that the existing communication should be interrupted. We may easily conceive, also, that before the earth had reached its pre- sent degree of cooling, hot springs must have been infinitely more numerous than they are at present. When, instead of one-thirtieth of a degree, centi- grade per yard, the temperature increased one-third of a degree, that is, ten times more rapidly than at present, and when water boiled at a depth of 325 yards, it is clear, there must have been a great many springs at a tempera- ture of 212 Fahrenheit, or of boiling water, and that fumarolles, now rare, were then common. Consequently, the condition of the atmosphere was then very different from what it is now ; thick fogs must have spread over the surface of the earth, in the absence of the sun, and hence radialion towards the celestial space, at present an important cause of refrigeration, must then have been nothing. Winter was consequently less rigorous ; and this ex- plains, too, how so many plants and animals, which cannot now exist in northern climates, could then live in them as between the tropics, and pre- cisely as southern plants now live on northern coasts and islands which are constantly shrouded in thick fogs. The whole earth, tempered by these * According to Fourier, a decrease of internal heat of not more than one degree in thirty yards, would require 30,000 years. 2. How is the temperature of hot springs accounted for ? At what depth do spring waters boil ? 148 DEPOSITS REFERABLE TO SEDIMENT. abundant vapours, could then support the same organic creatures ; here we have the reason why mineral beds, of a determined age, differ less in the organic remains they contain, wherever found, than existing creatures of different zones. DEPOSITS REFERABLE TO SEDIMENT. 3. Rolled flints, sand, and mud, are formed by the action of running water and of waves ; and, being transported by these waters, they accumulate in lakes,* in seas, at the mouths of rivers, and on coasts. Whenever we find these kinds of matter accumu- lated in more or less considerable deposits in the interior of coun- tries, we have a right to conclude that there existed somewhere, far or near, high mountains, from which these matters were detached ; water-courses, which carried them ; undulating waters, which heaped them up on their shores, and often lakes and seas, that received them. By the greater or less abundance and size of the rolled flints, we can judge of the mass and force of the waters that transported them; and their nature, and various course or track, ought to lead to the point of their origin, if circumstances have not destroyed the traces left by currents in their course. As in the present day we see deposits of shells formed in lakes and seas, we infer that the numerous beds of the same kind we find at all heights, even on the summits of the loftiest mountains, were necessarily formed under water ; the nature of the organic remains enables us to determine whether they were deposited under fresh or salt water, on coasts or in depths of the sea; their mixture, their alternation, indicate mouths of rivers, alter- nations of salt and fresh water, &c. 4. Deposits from fresh water. These deposits are easily re- cognised from me organic remains they contain being comparable to different genera, sometimes even to different species of animals now living in our lakes and rivers. These are especially remains, impressions, or moulds of shells, like those of the genus limne'a (Jig- 227), planor'bis (Jig. 228), paludi'na (fig. 229), mela'nia \fig. 230), and of land shells of the genus helix. These are all Fig. 227. Limne'a Fig. 228.- Piano' rbis Fig. 229. Paludi'na Fig. 230. Mela'- longisca'ta. euom'phalus. lenta. niainqnina'ta. 3. How are rolled flints formed ? What does the presence of a deposit of rolled flints in a country indicate ? What is inferred from their size and quantity ? MARINE DEPOSITS. 149 univalve, unilocular shells. The bivalve shells of fresh-water de- posits, more rare than the preceding, are like mussels u'nio (fig. 231), anodo'nta (Jig- 232), cy'clas (Jig. 233), and cyre'na (Jig. 234). The entire absence of every species of polypa'ria (figs. Fig. 231 U'nio Fig. 232. Anodo'nta Fig. 233. Cy'clas littora' Us. cordieri. obo'vata. Fig. 234. Cyre'na trigo'nula. 235, 236, 237239), and echini'deae (figs. 238240, 241), is an important characteristic of fresh-water deposits, which are very common in different parts of the" world. 5. Marine deposits. These are distinguished by the analogy of the organic remains they contain (figs. 235 to 250) to the' debris Fig. M5.Encri'nites monilifo' rmis. Fig. <236.j9'piocri'nites rotu'ndus. Fig. 237. Cy ' athocri 'nitea planus. 4. How are fresh-water deposits recognised ? Which are most numerous, univalve or bivalve shells, in fresh-water deposits ? What does the absence of polypa'ria indicate? 5. How are marine deposits distinguished ? What fossils are character- istic of marine deposits ? 13* 150 MARINE DEPOSITS. of different animals now living in the seas. Polypa'ria. more or less analogous to those which form coral reefs (figs. 220 to 223 p. 141), are highly characteristic; encri'nites (jigs. 235 to 237), Fig: 238. Cida'ris corona'ta. Fig. 239 .Different joints of Encri'nites. or the remains of their joints (fig. 239) the echini'dese (figs. 338 to 241). Not one of these organic bodies is found in fresh water Fig. 240. Qnanchytes ovatus from the Parisian chalk"). Fig. 'Hl.Spata'vgus ambula'crum (from the chalk of the Pyrenees}. Among the marine univalves there are some which are more or less analogous to those of fresh water, mentioned (p. 148), although they are thicker, and more gene- rally covered with tubercles (fig. 242). But, setting aside those on which at first sight there might be some doubt, there are many others which are sufficiently charac- teristic : these are shells whose aperture is terminated by a canal of greater or less length, and belong either to the genus ceri'- thium (fig. 243), of which a small number F lg .M.-Tur bo costa'nus. Q{ S* J genera mu'rex (fig. 244), volu'ta (fig. 245), &c. ; they are all marine, and abound in calcareous deposits. MARINE DEPOSITS. 151 Fig. 243. Ceri'thium muta'bile. Fig. <244.Mu'rex alveola' tus. athle' ta. Marine bivalve shells generally differ very much from those found in fresh water ; some resemble oysters, and others are almost entirely like them ; a great many are furnished with ribs, or striae, or rugosities (figs. 24(5, 247), and possess, in a word, many cha- racteristics entirely different from those found in the genera we have just mentioned. Fig %46.C!iama folia' cea. Fig. 247, re'nerica'rdia Mff. 284), into which it sometimes forces separate masses () ; fragments of limestone (6) are also found enveloped in the granite itself. In other places vertical veins traverse the rock (Jig> 285), sometimes entirely, sometimes terminating in pointed Fig. 284 Fig. 285. Injection of granite into different rocks. 19. What is the origin of granitic rocks? What rocks are included under the name of granitic rocks ? ' 20. What circumstances prove the igneous origin of granitic rocks ? METALLIFEROUS LODES, VEINS, MASSES. 173 masses, like the dio rites and basa'lts, which also shows that the matter came from below upwards, and that it was driven with great force. These facts do not present themselves in a particular locality only, but are observed in all parts of the world. The state of pasty fusion in which the granites were, is indicated by the manner in which these rocks are enveloped in certain sedimentary deposits, or effused on the different soils they pass through. In the coal-measures of La Pleau, to the south-west of Ussel, a portion of the formation has been enveloped by porphyroid granites, which are found above and below. ' The coal is there hard, as on all the plateau, and the deposit is very irregular. In a great many localities, we find granite superposed on all sedimentary deposits from schists, and the most ancient rocks, to those of the jura'ssic period. There are different places in the Alps, where one may touch at the same time, superposed rocks of crystallization and the subjacent sedimentary deposit. The action of granitic rocks on those through which they pass is the same as that of the preceding rocks ; compact, o'olitic, and earthy lime- stones are converted into saccharoid limestones, from which organic re- mains have most frequently disappeared ; they assume bright colours of every kind, green, red, black, &c., and, in contact with mica, are filled with garnets and various other crystalline substances. They are often converted into dolomites, which are nowhere more abundant than in formations of granite and sometimes into gypsum, as proved by the out-croppings of this substance in certain parts of the Alps. Clays, and various arena'ceous sub- stances are transformed into jasper, and finally assume the characters of mica'ceous or talcose schist, and gneiss. Simple sandstones of sedimentary formations, on the approach of granite, are converted into beds of granular quartz. It sometimes happens that modified schistose sandstones still pre- serve their arena'ceous structure, although they may have become very solid ; even the mica-schists to which they pass contain here and there thin strata of sandy quartz, interposed between laminae of mica, which seems to announce the remains of ancient modified sandstone. Granitic rocks, referred to different ages, are very abundant on the sur- face of the globe ; being found sometimes in very lofty mountain chains, and sometimes forming rounded hills disintegrated on the surface, and cover- ing considerable extents of country. 21. Metalliferous lodes, veins, masses. The dolomisa'tion and the sulphatisa'tion of limestones, the presence of various sub- stances in adjacent rocks, are not the only facts referable to the passage of igneous rocks from the bosom of the earth. It also happens that, on the contact of the new with the ancient rock, the deposits are filled with different metallic minerals, either dissemi- nated or injected into fissures, and between beds, or accumulated in small masses, sometimes united by slender threads. This has been remarked by M. Dufrenoy in regard to iron ores in the Py- renees, which are found either in limestone, or placed between sedimentary deposits and the granite which upheaved the solid mass. It is evident, lodes or seams of ores are related to igneous action. As to those which are deposited in veins, it is to be remarked, we have never had occasion to follow them to a sufficient depth to ascertain whether they ter- 21. How are metalli'ferous veins produced ? 176 METALLIFEROUS LODES, VEINS, MASSES. minate abruptly, and consequently whether they fill cracks opened from the surface towards the interior ; but they are known to terminate in pointed masses upwards, as at Joachimstal in Bohemia, and in many other places, in small veins which have been worked. This circumstance leads us to think that metalli'ferous veins have been produced by an injection from the interior towards the surface, in the same way as the stony veins we have mentioned. Besides, veins of this sort are strongly united to the others : thus, at Pontgibaud, the same veins are sometimes granitic and sometimes metalli'ferous ; in many other places metalli'ferous veins accompany por- phyritic veins, and even veins of basa'lt, as in Bohemia, and the two sub- stances mutually penetrate each other, sometimes one and sometimes the other being above. On the other hand, we very frequently find in the same localities stony and metalli'ferous veins running parallel to each other, sometimes crossing in different ways, one throwing the other aside, and thus mutually producing more or less marked faults. Sometimes the stony displace the metalli'ferous veins ; sometimes, on the contrary, the latter turn aside the others : in everything they act exactly alike, and it is impos- sible not to refer them to the same origin. It is also remarked that veins generally follow great lines of dislocation of the crust of the earth. We find in metalli'ferous veins the influence of those which pass through or accompany them, and which deposit, to a certain extent, substances not previously observed. The influence of the rock passed through is seen in metalli'ferous veins, as well as in those of trap; and it has been long known to miners, that a poor vein in a determined bed at once becomes rich by pass- ing into another, and the contrary : hence, the sudden success and unfore- seen reverses in mining operations. 22. Metalli'ferous masses being in general but accumulations of small veins running in all directions (fig. 286), or an abundant dissemination in the midst of a stony substance of the kind attri- Metalli'ferous b ute( J to t ^ e act i on o f fl re> ^ j s clear these deposits are produced in the same way as those just mentioned. These masses, the principal of which present us with ores of tin, copper py'rite's, and magnetic iron, are chiefly composed of granites, porphyries, various mag- nesian rocks, in which the ores are found. The metalli'ferous mass of Zinwald, in Bohemia, is a particular granite enclosed in a porphyry; that of Altemberg, in Saxony, is a ' porphyritic mass enclosed in gneiss. The celebrated mass of magnetic iron of Taberg, in Sweden, is a mass of diorite enclosed in gneiss ; that of Cogne, in Piedmont, is a mass of serpentine driven into the calci'ferous mica'ceous schist. 23. Metalli'ferous lodes in regular beds, are merely veins which have followed the stratification, as we observed in traps (fig. 283), or deposits which were formed in contact with sedimentary beas and the fused matters that upheaved them. But we must not con- found the masses and veins, just mentioned, with certain deposits of o'olitic iron ores found in sedimentary formations. Among the 22. Of what do metalli'ferous masses usually consist ? 23. What is meant by the term lode ? METAMORPHISM. 177 latter, some form beds of more or less extent in the midst of calcareous forma- tions, others fill wide apertures of little depth, from above, which sometimes communicate with caverns (fig 287) ; p . 2 87.-. but these facts are of a different order f rom t ] le exterior. from those just described. 24. Metamorphism. From all the facts we have cited (which might be vastly augmented in number by reference to details in many localities), we must conclude that crystalline rocks, which are all formed of si'licates, extensively varied and mixed with each other, have been produced by the action of fire ; that at different epochs they have dislocated, uplifted, or overturned the sediment- ary deposits, modifying the mass in all manners and it is to these great phenomena that are due all the seeming disorder observed on the surface of the globe, as well as all the successive changes, the traces of which may be perceived at every step. When we see earthy or compact limestones become crystalline on the approach of these different kinds of rocks to fill with various substances they do not contain at certain distances to be charged with magnesia in cracking in all parts, and to disintegrate with more or less facility ; when schistose clays and arena'ceous substances are converted into different jaspers, and become charged with mica and am'phibole, and assume the characters of gneiss, of mica'ceous or talcose schist ; finally, when sand- stones are transformed into beds of solid quartz, can we be surprised that most modern geologists have adopted the idea of complete changes effected in a great number of sedimentary deposits, and that they resort to this metamorphism, long since perceived by Hutton, Playfair, and Dr. Macul- loch, to explain a multitude of facts, observed especially in deposits anciently designated under the names of primitive and transition formations ? The facts appear so extraordinary, that we may be led to suppose a little ex- aggeration : but we must reject evidence to deny that there are saccharoid limestones, dolomites, mica-schists, gneiss, granular quartz, &c., which are the result of a change produced in earthy or compact limestones, clays, sands, &c. of sedimentary formation : is it then so ridiculous to suppose that such has been their origin in all cases? These ideas, now more striking, because they are expressed by a proper word, are nevertheless not absolutely new; all works on geology are actually full of them, and the facts are not less remarkable from being expressed in other terms. There is no description of a country, going back to the time of Saussure, whose works are still remarkable for their fidelity of details, in which are not seen numerous passages of different arena'ceous deposits to rocks of crystallization, of schistose grauwackes to talcose schists, to mica'ceous schists, and from these to gneiss, or the passage of sandstone to different kinds of granite and porphyries on which they rest, &c. Is not the fact of the modifications, now described under the term of metamor- phism, here clearly indicated to which time has added only more details and greater precision ? It is certain that in departing from schistose grauwackes, for example, and going towards some mountain or islet of crystallization, we find these 24. What is meant by metamorphisrn ? Of what do crystalline rocks consist ? 17S METAMORPHISM. substances themselves become more crystalline in character, and sometimes, without losing 1 the organic remains they contain, become filled with new minerals ; in Brittany these schists are filled with andalu'site, sometimes staurotides, near all granitic deposits. Elsewhere, as in Vosges, in the mountains of Var, we see them pass to mica-schist ; and the latter to gneiss, which, itself, insensibly becomes granite. Now, as if the intimate union observed were not sufficient, these mica-shists, then the gneiss itself, contain carburetted schist, or even graphite, veins of anthracite, which remind us of the deposits which are found further in the schists of grauwackes, and suffi- ciently marked to determine the pursuit of coal. It is, then, evident that all the rocks we have cited, no matter how they may differ, are only modifications, mere metamorphoses of one or all ; and, as it is in approaching granitic rocks, evidently produced by igneous action, that these metamorphoses become more and more marked, jt is clear that it is to the influence of the latter that they are due. The same influence is manifest on the sandstones of different ages, at various points where they are in immediate contact with granite : the modifications are such that the special name, arkose, has been applied to them. They then pass through all shades to granite, and become filled with different substances that they do not contain elsewhere. Near porphyritic ejections, schists frequently present modifications of an- other kind. Here the most earthy, and the most evidently sedimentary parts, pass by degrees to compact substances, more and more fcldspathic, preserv- ing more or less of their schistose character, and finally end by containing crystals of feldspar ; elsewhere these same matters pass to solid clays, con- taining veins of limestone, then nodules of the same substance, which as- sume all the characters of amygdaloids, losing, only little by little, their schistose structure. The same phenomena are remarked between diverse sandstones and por- phyries that intersect them. The arena'ceous matter gradually hardens, becomes more compact, and finally unites with the porphyry in such a manner that it is not easy to determine where one begins or the other ends. All these facts pertain really, with the exception of some details, to ancient geology ; and it is only the manner of explaining them that has changed. Everything conspiring to demonstrate that crystalline substances have been produced by the action of fire, and forced through sedimentary deposits, we now understand that the latter have been modified, or metamorphosed in different ways by their influence, in a degree corresponding to their proxi- mity : the effects entirely cease only at greater or less distances. It is conceived that one part of these metamorphoses of sedimentary forma- tions arises from the simple action of heat without new fusion, but sufficient to modify the texture of masses, and even to unite elements in other propor- tions, as happens when transparent glass is submitted to a temperature in. sufficient to melt it, in which, nevertheless, a new crystallization takes place. But this idea is not sufficient of itself; we must conceive another action, which we are not yet able to explain or account for, in virtue of which par- ticular substances have been borne, or developed, in the midst of rocks found in the neighbourhood of divers upturnings, of which the globe is the theatre. We readily conceive of the introduction of sulphuric ac;d, which is frequently formed in volcanoes ; but we do not understand that of magnesia and diffe- rent species of si'licates, and, as respects them, all is still purely hypothetical. We may compare these facts to ctmenta'tion, by means of which iron is converted into steel ; a phenomenon which is manifested not only in contact with carbona'ceous matter, but extends far into the ferru'ginous mass, and even takes place at a distance, according to the experiments of M. Laurent, who has shown that carbona'ceous matter may penetrate iron even through EFFECTS ATTRIBUTABLE TO EROSION. 179 porcelain tubes. We also know, from experiment, and many effects ob- served in manufactories, that the peroxide of iron, the oxides of chrome, &c., are vola'tilized, and penetrate the substance of bodies that envelope them. The experiments of M. Gaudin, with a blow-pipe on a de'tonating mixture, show that silex, magnesia, and lime, are also volatile oxides ; the first after fusion, the others before being melted. These facts evidently lead to an ex- planation of all the phenomena of metamorphism, arid the intrusion of foreign substances into sedimentary deposits, either in veins or in a state of dissemination. EFFECTS ATTRIBUTABLE TO EROSION. We have seen that waters act by the carbonic acid they contain ; by their Weight; by their dissolving power; by their transporting power; by their shock, as in waves of the sea, and thus denude continents. We have also pointed out, that in arena' ceous formations, valleys are produced by erosion, precisely as ravines are formed in sandy soils, by the action of rain-water. Hence we may infer that, in every revolution that movements of the soil must have necessarily determined, the waters, thrown forcibly sometimes on one side and sometimes on the other, must, as in our time during earth- quakes, have ravaged, divided, and modified pre-existing deposits in various ways. Many circumstances may be explained by erosion of waters, and the denudations it occasions. 25. At first, when we see more or less numerous hillocks of sedimentary matter in a country (Jig. 288), whose summits are Fig. 288. Hills produced by denudation. nearly on the same level, and whose strata correspond with each other, we are naturally led to consider them as evidence of great removals effected by the waters, at certain epochs, the relative dates of which remain to be ascertained. In this way we explain, according to appearance, all the sections which the sandstones pre- sent on the eastern slope of Vosges ; that remarkable assemblage of peaks of every form seen at Aldersbach, in Bohemia ; the nu- merous hills that cover Ross-shire, in Scotland ; the gypseous hills in the neighbourhood of Paris, all composed of the same beds placed at the same height ; and the division of the basa'ltic tables that crown the hills, in certain localities, as well as the rupture of certain lava-floods that had barricaded valleys, &c., &c. Valleys which intersect moveable formations are evidently produced in the same way; and there is no doubt that most of those existing in solid forma- tions, have been modified by erosion of water after the rupture which gave origin to them. In this way we may explain the smoothing of all their parietes, in a great many localities, and the widening of their upper parts. The great lakes sometimes found at the extremity of valleys, as on the two slopes of the Alp.-;, in Switzerland and Piedmont, may be attributed to the afflux of waters which rushed through them, at the period of some great ca- tastrophe, and emptied with violence on the plain in which they terminated. 25. What forms of surface are attributable to erosion and denudation ? 180 EFFECTS ATTRIBUTABLE TO EROSION. Many other facts are explained by the power of erosion and transport by water. When, by studying faults in the interior of mines, we clearly see that the beds no longer correspond, and that a part of the formation must have been uplifted (Jig. 289) ; then, if the soil, a, i, c, is level on the surface, Fig. 289. Fig. 290. we naturally ask what has become of the beds d and /, which ought to have formed a hillock between b and c. It is clear these beds must have been removed, which we may conceive was only by a posterior action of waters, which carried away the debris, and perhaps spread them over the surface. In the same way, when we see a vein form a projection, a dyke on the sur- face of the soil (Jig. 203, page 119), we conceive that it could not have formed in this manner, and that the uncovered part, must have been once encased just as that is which is now covered ; the surrounding formation has been uplifted then afterwards, at least along the whole actual height of the projection. Something similar necessarily took place at points where veins crop out on the surface, or are covered by moveable soil (fig. 290) ; it is not probable that melted matter injected in the crack would be immedi- ately arrested at the surface of the earth, and it is presumable that the soil has been removed and subsequently covered by various clearings. We are thus led to understand how so many basa'ltic masses now offer no trace of scoria'ceous matter, neither in themselves nor in their vicinity. These im- perfectly aggregated debris have been subsequently carried away by the action of water, and perhaps it is the same with the scoria'ceous matter which must have accompanied the appearance of trap. The prodigious power exerted by waves, and the effects they have pro- duced in our times, lead us to think, also, that all the rocks formed around islands and reefs at a short distance from coasts, or the often fanciful groups in the midst of the sea, are also the remnants of some great division caused by water, as much in removable matters, easily disintegrated, as in masses broken by earthquakes and different movements of the soil, and certain parts of which have been afterwards removed, either by repeated shocks of waves or sudden debacles. In this way we may explain the numerous accidents in rocks which bound coasts, or are isolated in the midst of the ocean, as in the sinkings of the chalk of Etretat (fig. 291), and the sec- tions of porphyritic or granitic rocks in the Shetland islands (fig. 292). It is conceived that straits, more or less extended, may have been formed by the two combined actions of currents of water and rupture which the soil might have undergone, by upheaval or subsidence, at determined epochs. From these observations, we see that many effects may be attributed to the action of water which cannot be in any other way explained. We may see denudations in the rnidst of mountains and valleys, recognise the ancient sinkings which bordered seas at different ages, and hence appreciate their limits, as well as all other circumstances connected with them. Reference to the immediate action of water should be always carefully restricted to the moveable or loose matters found on the surface of the globe ; for when solid matters are in question, which water attacks too slowly, we are led to CLASSIFICATION OF FORMATIONS. 181 Fig-. 291. Fig. 292. Examples of rocks cut and fashioned by water. think that currents and waves cannot act effectively until the soil has been previously prepared by the fissures or deteriorations caused in rocks by movements of the earth. We must not confound with divisions produced by water certain accidents which may result from shrinking produced by metamorphism. This pro- bably takes place in dolomites, which follow compact limestone in a great many places, as in the Tyrol and in Cevennes. Masses of these matters are frequently split and slashed in all directions on the surface, particularly on the summits of mountains or on plateaux, very nearly in the same way that calcareous deposits are cut by water. Now, the change from a simple to a double carbonate, specifically heavier, requires contraction in masses submitted to dolomisa'tion ; therefore, the latter must be split and cracked in all directions, and the denudations they present are consequences of these effects. LESSON X. Classification of Formations Different kinds of Stratification Dip Strike Conformable Stratification Unconformable Stratification False Stratification The form and habits of an Minimal deducible from a single bone Relative ages of the principal catastrophes of the Globe Systems of Upheaval Classification of State of Europe at different epochs of forma- tion Deluge Geogeny. Classification of Formations. 1. As already mentioned, the several formations are divided into two ciasses, namely : 1st. Massive, or igneous formations, which are produced by the 1. How are the several formations divided ? 10 What are the divisions ? 182 CLASSIFICATION OF FORMATIONS. action of fire, and are not stratified. The terms primitive and transition have been applied to these formations, but, as they are inexact, they are going out of use. 2d. Sedimentary formations, which are deposited by the action of water, and are stratified. 2. MASSIVE, or IGNEOUS FORMATIONS escaped from the earth in a state of fusion, and became solid by cooling, but without being stratified. They are divided into two classes : 1st, those crystal- line rocks which are not traceable to the crater of any volcano now recognisable, such as granite, trachyte, &c. ; 2d, massive rocks of a slightly crystalline structure, traceable to volcanoes, such as modern and ancient lavas, and basa'ltic formations. 3. SEDIMENTARY FORMATIONS are arranged according to their relative antiquity : they are divided into groups, composed of those which appear to have been formed either at the same epoch or during a geological period, during which the general condition of the earth appears to have undergone no important change. These formations are commonly divided into five groups, namely: 4. First. Primary stratified rocks, in which neither organic remains, nor fragments of the most ancient rocks are found ; this group includes gneiss, mica-schist, quartz,, transition limestone, and argilla'ceous schist. 5. Second. The transition formations, which rest on the pri- mary stratified rocks, and contain fossils of plants or animals, but which appear to have been deposited prior to the creation of the most perfect beings of either kingdom, and only contain the remains of aquatic animals, which are all very different from those of our times, such as tri'lobites (fig. 4, page 28). This group includes fossili'ferous schists, transition limestones, &c. 6. Third. The secondary formations were deposited at periods less remote than the transition, and consequently rest on beds of the latter, or on .primary rocks ; but they go back to a time when the state of the globe was very different from its present condition ; very few mammals then existed ; ammonites are among the most characteristic fossils of the secondary formation : The secondary formations are subdivided into, 1st. The carboniferous, which includes old red sandstone, mountain lime- stone, and coal : 2d. The sali'ferous, embracing new red sandstone muschelkalk, and variegated marls, forming the tria'ssic system : 2. What are the divisions of the igneous formations ? 3. How are sedimentary formations arranged ? How are they divided ? 4. How are primary stratified rocks characterized ? What rocks are included in this group? 5. On what do the transition formations rest ? How are they charac- terized ? 6. On what do the secondary formations rest ? What are the most cha- racteristic fossils of the secondary formations ? How are they subdivided ? What are the divisions ? MEANS OF DISTINGUISHING FORMATIONS. 183 3d. The jura'ssic, embracing the lia'ssic, the o'olitc, and wealden groups : 4th. The creta'ceous, embracing the lower greensand, gault, upper green- sand, chalk marl, chalk without, and chalk with flints. 7. Fourth. The tertiary formations, which, being more re- cent, covered all the preceding formations ; they date from a period when animals and plants belonging to all the great classes existed, but still anterior to the creation of man : The tertiaries are suhdix'ided into three groups ; 1st. The older tertiary or eocene, which embraces the London clay, bag- shot sand, and Paris Basin. 2d. The middle tertiary, or miocene, which embraces the Coralline crag, Red crag, the Molasse of Switzerland, &c. 3d. The newer tertiary, or Pliocene, which embraces Norwich crag, the sub-Apennine beds, the Brown coal of Germany, &c., as well as the super- ficial deposits, called Pleistocene, consisting of diluvium and alluvium. 8. Fifth. The modern formations, which are contemporaneous with the existence of man on the earth, ;md are still being formed. The subdivisions embrace : 1st. Peat-bogs, formed by the accumulation of the debris of certain plants. 2d. Coral formations, from the multiplication of polypa'ria as seen in the coral islands of the Pacific. 3d. Concretionary formations, formed by calcareous and other matters, found in solution in the waters of certain springs, &c. ; as travertin, stala'c- tites, stala'gmites, &c. 4th. Formations from transport or drift ; as fluviatile, terrestrial, or marine alluvions, dunes, &c. 5th. Humus, or vegetable earth, formed directly by the disintegration of other formations, and their mixture with the products of decomposition of plants and animals, spread in a layer of more or less thickness, on almost every point of the surface of the earth. 9. All these deposits are superposed one on the other, in a con- stant order; and if it were possible to make a sufficient section in a part of the globe where they all exist together, we should find a succession of twenty-seven stories, or layers, distinguishable by their different characters. But each of the great deposits is divided and subdivided into various layers, more or less distinct, composed most frequently of arena'ceous substances, clay and limestone, of different degrees of consistence, and in beds of varying thickness. The assemblage of their alternate beds often forms successive layers, several hundred yards thick. 10. It is evident, that if such sections existed in the crust of the earth, we could see all the beds, and easily distinguish their rela- 7. From what period do the tertiary formations date ? What are the divisions of the tertiaries ? 8. From what period do the modern formations date ? What formations are embraced in the divisions of the modern formations ? How is humus formed ? 9. What is the arrangement of the several deposits composing the crust of the earth ? 10. Why is it difficult to distinguish the relative ages of deposits? 184 RELATIVE AGES OF DEPOSITS. live ages by their number in the order of succession ; the deepest being the most ancient, and that forming the surface being the most modern. It would then be sufficient, in sections of different depths which would be found elsewhere, to count from above downwards, to know always where we were, and even the variations that a determinate bed might undergo in different places would offer no difficulty to observation. But such is not the case ; the numerous escarpments we meet, always present us with but a very small portion of the series, sometimes in one part of its thickness, and sometimes in another ; we never see the entire series ; and it is only by combining the observations made in different places, that we have been able to establish what we now know, at the same time we discovered the particular circumstances of formation of each deposit. In consequence of the divisions of the whole, it is conceived, it might be- come very difficult to distinguish them, and that in presence of an escarp- ment one might frequently be unable, at first sight, to decide on the point in the series to which it ought to be referred. Indeed, different beds of the same nature which succeed each other in the series, are often very analogous, the limestones of one story more or less resembling those of another ; and the same is true of different deposits of sandstone and clay. It also happens that the same deposit varies at different points : here it is a compact, and there, an earthy limestone ; in another place the same limestone is found mixed with sands, and, further on, it is nearly pure sand, &c. The injection of crystalline matter adds to the embarrassment, by the modifications it causes in the texture, and even in the nature of everything in its vicinity. It is also conceived, that the fewer the beds superposed in the same place, the greater the difficulties, and they are at a maximum when we meet an isolated deposit, without knowing on what it rests, and not being able to perceive anything it covers : this occurs in a great many countries. It often happens, too, that one or more beds are entirely wanting in one locali- ty, and then the deposits which should naturally separate them, being im- mediately superposed, exposes the observer to attribute to the succeeding beds an age very different from that which really belongs to them. 1 1 . To obviate this difficulty, we have observations on the con- tinuity of beds, some of which we can follow from points where they present certain characters, to others where they offer different characters; from points where they are entirely isolated, to others where we can see on what they rest, and what covers them, &c. We have also observations on stratification and inclination of different beds towards one point or the other, which enable us to infer that such a species of deposit passes below or above another, found isolated or at a dis- tance. Fragments and rolled flints may evidently indicate the priority of deposits which contain them, to those from which they came, and thus fur- nish a good means of distinction, when they are sufficiently characterized. And the nature of organic remains has now become a very decided aid in distinguishing different formations. 12. Different kinds of stratification. There are two kinds of 11. How are we enabled to judge of the relative ages of deposits ? 12. How many kinds of stratification are described ? What is observed in inclined stratification ? DIFFERENT KINDS OF STRATIFICATION. 185 stratification : one horizontal (which is the natural stratification), according to which all transported matters are deposited under water ; the other more or less inclined, resulting from upheavals which have taken place at different epochs. In the latter we dis- tinguish the degree of inclination, or dip, which may be vertical, and the point of the horizon towards which the beds dip. The last part of the observation determines the direction of the crests of the strata, or, as we say, the strike or direction of the strata, which is always at right angles to the dip or direction of the inclination, and which also indicates the direction of the movement by which the effect was produced. But the first observation of horizontal, or inclined strata, is not always sufficient ; it is frequently necessary to distinguish the relative stratification of different deposits, which is reduced to the concordance, or the discordance which may exist between them. 13. The dip of strata is the point of the compass towards which they slope, while the angle they form with the plane of the horizon is called the angle of dip. The term dip refers to the inclination of a stratum, and the term strike is used to express its direction. Thus, strata may dip to the north at an angle of forty-five degrees ; in this case, the strike, or line of bearing, must necessarily be east and west, because the strike is always at right angles with the dip. " Dip and strike may be aptly illustrated by a row of houses run- ning east and west, the long ridge of the roof representing the strike of the stratum of slates, which dip on one side to the north, and on the other to the south." The angle formed by the roof with the plane of the horizon would be the angle of dip. 14. Conformable stratification. When all the strata of a forma- tion are parallel to each other, that is, when there is a concordance between them, whatever may be their general position, horizontal or inclined, convex or concave, they are said to be conformable (Jigs. 293 to 296). Fig-. 293. Fig-. 294. Fig-. 295. Fig-. 296. Different, kinds of conformable stratification. 15. Unconformable stratification. When the strata of a forma- tion are not parallel to each other, when there is a discordance between them, as where horizontal strata come in contact with 13. What is meant by the dip of strata? What is the angle of dip? What is meant by the term strike ? 14. What is meant by conformable stratification ? 15. What is meant by unconformable stratification ? Is it always of the same character ? 16* 186 UNCONFORMABLE STRATIFICATION. inclined beds (Jig. 297), or where the relative inclination of beds is different, as at a and b (Jig. 298), they are said to be uncon- forrnable. Where a superior deposit, whether stratified or not, rests on a section of the beds of an inferior deposit (Jig. 299), there is a peculiar kind of unconformable stratification, sometimes called transgressive stratification. There is another kind of unconform- able stratification, where the beds are parallel ; this occurs where a horizontal deposit, after having been furrowed in different ways by water, is again entirely covered by a deposit of the same nature which fills up all the excavations (Jig. 300). In this case the strata are unconformable where they join end to end with beds on the slope of ancient valleys. Fig. 297. Fig. 298. Fig. 299. b Fig. 300. Examples of unconformable stratification. 16. To ascertain the relations in the stratification of two deposits, it is necessary to pay great attention to the particular structure of the beds, which in certain cases may lead us into error. For ex- ample, seeing that the divisions of the bed , (fig. 301), dip to- wards the left of the figure, we must not conclude that the strati- fication is unconformable with the bed b ; this appearance results altogether from the structure which the bed a owes to its rapid formation under particular circumstances. (See page 138.) Fig. 301. Fig. 302. Examples of doubtful stratification. 17. Schistose substances often present many difficulties, in this respect, because their divisions run in every direction, and some- times the least apparent is the real stratification. For instance, we might suppose, the deposit a, (fig* 302), rested conformably on the deposit b, and that the mass c is an unconformable stratification, from regarding the finest divisions of the schist as indicative of the stra- 16. What is meant by doubtful stratification? 17. What is false stratification? FALSE STRATIFICATION. 187 tification. But we might also consider the deposit a as unconform- able, and the deposit' c as conformable, from regarding the parallel joints., i to &, as those of stratification ; and it is also possible to view both a and c as unconformable relatively to 6, by considering the other joints as those of the strata. It may be often difficult to decide ; nevertheless, in general, the schistose division is frequently a structure which has perhaps a certain crystallization of mica'- ceous matter ; and it is this character, therefore, among others, that we must ordinarily select. Now, the joints of dislocation, for one or the other division must have been thus produced, are splits united arid well marked, often a little open, which are ordinarily prolonged into several consecutive deposits, ,/ while the joints of stratification are more un- jlU dulated and more adherent. The most irregu- /// lar undulations of true strata are often tra- versed throughout by the schistose structure (fig. 303), without alteration. This circum- stance evidently shows that this structure is an effect posterior to the contortion of beds, and may be attributed to a metamorphism more modern than their derangement. The extraordinary divisions just mentioned, are Fig.3Q3. sometimes termed false stratification. 18. Organic remains, which are very numerous in most sedi- mentary deposits, also furnish a means of recognising strata. There are some which are peculiar to certain deposits, and are not found elsewhere, and which are therefore distinguished as geo gnostic horizons. Thus, the Silurian or Devonian formations are clearly recognised by the presence of the remains of a cer- tain family of crusta'ceans, named trilobites (fig. 4, p. 28). The Gry'phca arcua'ta (fig. 71, p. 55), is found in the has, and only in it : the ex'ogy'ra vir'gula (fig. 109, p. 65), belongs to the upper part of ,the jura'ssic formation ; baculites (fig. 130), and turrili'tes (fig. 131, p. 72), begin and end in the creta'ceous period. 19. Although the remains of mollusks and small animals are found entire, and therefore easily recognised, those of large mam- mals, &c., often exist only in fragments ; and, without the neces- sary knowledge, the family, genus, or species, could not be dis- covered. But those well acquainted with comparative anatomy, and the laws which govern in the organization of animals, can deduce the form, and even the habits of an animal, often from a single bone. " Every organized being may be considered as an entire and perfect sys- 18. How do organic remains assist us in distinguishing the relative age of strata ? 19. How is it that a portion of the fossil remains of an animal enable us to recognise its class ? 188 AN ANIMAL MAY BE KNOWN FROM ONE OF ITS BONES. tern, of which all the different parts mutually correspond, and concur in the same definitive action by a reciprocal re-action. No one part can undergo a change without a corresponding change taking place in all the others ; and, consequently, each part taken separately, indicates and gives the key to a knowledge of all the rest. " Thus, if the stomach of an animal is so organized as only to digest fresh animal food, its jaws must also be so contrived as to devour such prey ; its claws, to seize and tear it ; its teeth, to cut and divide it ; the whole struc- ture of its locomotive organs, to pursue and obtain it ; its organs of sense, to perceive it from afar ; and nature must have even placed in its brain the necessary instinct to enable it to conceal itself, and to bring its victim within its toils. Such will be the general conditions of a carni'vorous animal ; they must inevitably be brought together in every species intended to be carni'- vorous, for its race could not subsist without them ; but under these general conditions there exist also special ones, relating to the size, the habits, and the haunts of the prey, on which the animal is to exist; and from each one of these special conditions there result certain modifications, in detail, of the form re-quired by the general conditions ; so that not merely the class, but the order, the genus, and even the species, will be found expressed by, and deducible from, the structure of each part. " In order, for example, that the jaws may be enabled to seize the prey, there must be a certain shaped prominence for its articulation ; a certain relation between the position of the resistance and that of the power, with respect to that of the fulcrum ; a certain magnitude of the muscle that works the jaw, requiring corresponding dimensions of the pit in which that muscle is received, and of the convexity of the arch of bone beneath which it passes, while this arch must also possess a certain amount of stiength, to enable it to bear the strain of another muscle. "That the animal may be enabled to carry off its prey, a certain degree of strength is necessary in the muscles which support the head ; whence results a peculiar structure in the vertebrae to which these muscles are at- tached, and in the back of the skiill where they are inserted. " That the teeth may be adapted to tear flesh, they must be sharp ; and they must be more or less so, exactly according as they are likely to have more or less flesh to tear, while their bases must be strong in proportion to the quantity of bone, and the magnitude of the bones they have to break. Every one of these circumstances will have its effect on the development of all the parts which assist in moving the jaw. " That the claws may be able to seize the prey, there must be a certain amount of flexibility in the toes, and of strength in the nails ; and this requires a peculiar form of the bones, and a corresponding distribution of the muscles and tendons ; the fore-arm must possess a certain facility in turning ; whence also result certain forms of the bones of which it is made up; and these bones of the fore-arm, articulating to the humerus, cannot undergo change without corresponding changes taking place in this latter bone. The bones of the shoulder also require to have a certain degree of strength, when the anterior extremities are to be used in seizing prey ; in this way again other special forms become involved. The proper and free play of all these parts requires certain proportions in all the muscles concerned in the mo- tions of the fore-leg, and the impression of the muscles so proportioned will determine still more definitely the structure of the bones. " It is easy to perceive that similar conclusions might be drawn as to the structure of the posterior extremities, which contribute to the rapidity of the general movement of the body ; or of the vertebrae, which influence the facility of those movements ; and also as to the structure of the bones of the face, in their relation to the degree of development of the external senses. In RELATIVE AGES OF THE GLOBE'S CATASTROPHES. 189 a word, the structure of a tooth involves that of the socket in the shoulder- bone, and of the nails, just as to use a mathematical, but very apt illustra- tion the equation to a curve involves all the properties of the curve ; and as the curve may be drawn when we know the root of the equation, so in comparative anatomy, by making each property separately the base of in- vestigations, one may deduce all the other properties. Thus the shoulder bone, the articulation of the jaw, the thigh-bone, or any other bone, taken separately, gives the structure of the tooth, or, conversely, from the tooth, a knowledge of these peculiarities may be derived ; so that, taking any one bone, he who is familiar with the laws of the animal economy, may repro- duce the whole animal." Ansted. RELATIVE AGES OF THE PRINCIPAL CATASTROPHES OF THE GLOBE. From observations, it would seem that the dry land must have appeared in successive portions, to cause on the surface all the variations of nature, form, humidity, and dryness, the combination of which should procure for man all the happiness designed for him by the Creator. The study of the successive appearances of land is now one of the most beautiful points of view in which geology can be presented ; we are indebted to M. Elie de Beaumont for pointing out the course to follow, to establish the chronological order of the principal catastrophes which happened in Europe, and around which all facts of the same nature may be grouped. As soon as we perceive some part of inclined sedimentary beds, we may decide that they have been displaced from their ordinary position by up- heaval. The period of this accident remains at first undetermined ; but if, at the base of more or less elevated projections which these beds produce, we find other sediments deposited in horizontal strata, resting against the preceding (Jig. 304), it be- comes evident that the upheaval of the first took place after the formation of the second, which are still found as they were when deposited from p- ^Q^ water. We now have a term of comparison, and, if we succeed in recognising the relative age of the horizontal deposit, we also have an epoch of the catastrophe, relatively determined, which pro- duced the uptilting of the other. These differences of stratification are everywhere seen on the sides of mountains, and we then see that the several sedimentary deposits, a, 6, c, are not all in the same position. In certain places the stratum a, for example, is uptilted, and the stratum b is horizon- tal ; in another, a and b are both uptilted, and c is horizontal ; in a third, a, 6, and c, are uptilted together, and another stratum, d, rests upon them. We must infer, from these observations, that a first upheaval took place after the formation of a, and before that of b; a second took place between the strata 6 and c, a third between c and d, &.C., and so on, chronologically, as far as they have been observed. Systems of upheaval. If the inclined position of sedimentary strata reveals to us the existence of upheavals, the strike or direction of these beds, which is nothing but the line produced by their swelling upwards or the crest or ridge resulting from their rupture, shows us the course followed by the phe- nomenon. Hence it follows we may take one fact for the other, as the basis of observation, and that the different directions (strikes) of mountain chains, are also indications of the different kinds of upheaval. In fact, it has been long and perfectly established, on one hand, that the inclination of strata is intimately connected with the direction of chains, excepting the perturba- tions which result from crossings ; on the other hand, we now know that the phenomenon of uptilting of a determinate number of beds extends as far as the chain itself. It has also been ascertained, at least for Europe, that parallel chains correspond, in general, in the epoch of upheaval ; that is, m 190 SYSTEMS OF UPHEAVAL. these chajns, strata of the same age are found every where uptilted, and that the succeeding ones are horizontal. It follows from this circumstance that an upheaval does not take place purely on a mathematical line, but on a band of formations more or less wide, on which it is manifested by several parallel ridges. The same line does not continue always from one end to the other, but we find here and there high and low parts, and those which are concealed by subsequent deposits ; therefore, it is the common line of all the elevated ridges which must be taken for the general direction or strike (The word strike is formed from the German streichen, to stretch, to extend). 20. The assemblage of directions on the same line, and paral- lel directions, form what is called a system of upheaval, which is synonymous with the expressions, system of fractures, system of uptilted tfeds, and even system of mountains, although in a more restricted sense than in geography. To designate the different systems, the names of places in which each system is particularly developed have been borrowed ; we say, system of the Pyrenees, system of the Western Alps, &c. The great catastrophes which have successively opcurred on the surface of the globe appear to have always taken place suddenly. At greater or less distances from places where the stratification is unconformable, we often find the same deposits in conformable stratification, and even joined to each other by a gradual passage ; hence, it follows that deposition has not been suspended, but the movement of the soil has been local over a more or less considerable space of the terrestrial surface, and the interval during which it took place must have been extremely short. This is clearly seen, for example, at the period of the system of the Rhine, in which the vosgean sandstone is found upheaved, without the bunter sandstein having partici- pated in the action ; and, nevertheless, at a short distance the two arena'- ccous deposits, where their stratification is conformable, are so joined to each other, that it cannot be determined where one begins or the other ends. The same is the case with the creta'ceous formations ; if their different deposits are dislocated in a certain direction, they are conformable for great extents, and they then pass from one to the other in such a manner that they were for a long time confounded as a single formation. Submerged and uncovered formations. Sedimentary beds found resting horizontally on the sides of mountains, show that the sea beat against escarpments by deposits upheaved in an anterior epoch ; hence the expres- sion of the sea of this or that formation, as the creta'ceous sea, the jura'ssic sea, &c., which indicate the waters beneath which each of these sedi. mentary deposits was formed. When a deposit is wanting in a certain extent of formation, we shonld infer the formation was then above the sea of the epoch, and formed there a more or less elevated island or continent ; thus, at the lime when the Parisian limestone was formed, a great part of France, and indeed of Europe, must have been dry, as we scarcely see traces of these deposits anywhere except in the neighbourhood of Paris or Bordeaux. But it also happens that the deposits which we must regard as having been dry at a certain time, were afterwards covered by marine sediment, more modern than the preceding ; and hence we must conclude that, although uncovered prior to the anterior formation, they must have afterwards sunk to receive new deposits : such sinkings make certain catas- trophes particularly remarkable. 20. What is meant by "system of upheaval"? What is meant by cre- ta'ceous sea? How are the several systems of upheaval classed ? EPOCHS OF EUROPEAN FORMATIONS. 101 The several systems of upheaval have been classed according to their direction, and the epochs in which they occurred. The following table exhibits the supposed epochs of the European upheavals. 1st, Lpheaval, or system of Hnndsruck, between the cambrian and silurian formations. 2d, or system of Ballons, between the silurian and coal formations. 3d, or system of the North of England, between the coal and penine formations. 4th, or system of Hainault, between the penine and vosgean formations. 5th, or system of the Rhine, between the vosgean and trias formations. 6th, or system of Thuringerwald, between the trias and jnra'ssic formations. 7th, or system of Cote-d'Or, between the jura'ssic and greensand formations. 8th, or system of Mont-Viso, between the two creta'ceous formations. 9th, ' or system of the Pyrenees, between the upper chalk and Parisian limestone " 10th, ' or system of Corsica, between the Parisian limestone and molasse formations, llth, ' or system of the Western Alps, bet. the mnlasse and siibapennine formations. 12th, ' or system of the principal Alps, bet. the subapennine and diluvium. 13lh, ' or system of Tenare, between the diluvium and perhaps some modern alluvions. Since in Europe the different great chains of the same direction, which are found on the same line or on parallel lines, belong to the same epoch of upheaval, there is room to suppose, as nothing indicates limits to the phe- nomena which gave rise to them, that the same effects were continued far beyond the countries whose geological structure is known ; hence it follows, that wherever we find parallelism in the chains, we should be led to believe also that the formations were contemporaneous. It is at least interesting to examine, under this point of view, the principal chains we are acquainted with. The direction of the Pyrenees extends from the Alleghanies, in North America, to the peninsula of India, through the Carpathian mountains, a part of Caucasus, the mountains of Persia, from Erivan to the Persian Gulf, and through the Ghauts, which determine the position of the coast of Mala- bar. To the south of this line of direction several parallel ridges are also represented : those which go from Cape Ortegal, in Asturias, to Cape Creux, in Catalonia; the small chain of Granada, which ends in Cape de Gatte ; the mountains which bound the desert of Sahara on the north, cutting the direction of Atlas ; finally, the Apennines, the Julian Alps, the mountains of Croatia, of Romelia, and those of the Morea. The system of Ballons, so near to that of the Pyrenees, appears to be represented also in the Alleghanies : it is to be observed on the coast of Brittany, and will no doubt be found in several of the groups just mentioned, when careful study enables us to distinguish it from the neighbouring system. The direction of the Western Alps is remarked from the empire of Mo- rocco to Nova Zembla, passing through the eastern coast of Spain, the south of France, and a great part of the peninsula of Scandinavia. It is recognised in the Cordillera of Brazil, from Cape St. Roque to Montevideo. Parallel to this direction the same system is seen in the kingdom of Tunis, in Sicily, the point of Italy, and in Asia Minor. All the shore of the ancient conti- nent, from North Cape, in Lapland, to Cape Blanco, in Africa, is parallel to the direction of this system. The principal Alps form part of a system of direction of great extent. From the chains of Spain and those of Atlas, in the northern part of Africa, we find parallel chains which extend to theChina sea. On this line of direction we find, starting from Sicily and Italy, the chains of Olympus, in Greece, the Balkan, Taurus, the central chain of Caucasus, crowned by Elbrouz, between the Black and Caspian seas, the long series of mountains which extend through Persia and Cabool, comprehending Paropamisus, Hindou- koh, &c. ; finally, Himalaya, the highest mountain in the world. STATE OF EUROPE AT DIFFERENT EPOCHS OF FORMATION. From what has been stated, we are led to infer that the surface 192 SILURIAN AND DEVONIAN EPOCHS. of the globe, so often disturbed, must have presented great varia- tions in the relative extent of land and sea, and successively passed through many different shapes, to reach its present state. But, even in Europe, the only part of the world in relation to which positive information has been obtained, it is very difficult to say what may have been its condition in the most ancient epochs. The reason of this is, that having for a long time confounded, under the name of transition formation, deposits of very different epochs, we are not now able to distinguish, with sufficient clearness throughout, the limits of different formations comprised in- it. Nor do w r e know, and this is a great obstacle to tracing the continents of the ancient world, what parts were successively sunk at each catastrophe, and the extent of which we can only know from induc- tion. It was not until after the appearance of the jura'ssic forma- tion, the limits of which are clearly marked, that we are able to distinguish, with precision, the shape and extent of lands in the midst of seas in which these deposits were formed. By the term epoch of this or that formation, we understand the period of time during "which the formation was produced beneath the sea, around the upheaved deposits of the preceding epoch. For example, the jura'ssic epoch indicates the time during which the deposits of the Jura were formed in the seas where the upheaved deposits of the trias and all that preceded were traced. The term, sea of such an epoch, as jura'ssic sea, creta'ceous sea, &c., is often used in the same sense. Silurian and Devonian epoch. At the time when the Silurian and Devonian systems were formed in the midst of seas, it is evi- dent there were different portions of land in Europe uncovered, which resulted as much from the upheaval of the Hundsruck as from previous catastrophes : we have seen those of considerable extent which entirely escaped these deposits, and which, in conse- quence, must have been raised above the waters in which they were formed. In France, there was at least one island, of the Cambrian formation, near the gulf of St. Malo, on a part of Brittany and of Nor- mandy; the great granitic plateau, w r hich comprises Limousin, Au- vergne, &c., where the upheaval of the Hundsruck was manifest by the direction of certain uptilted beds of gneiss, and by the anfracluosi- ties in which the coal formation was subsequently deposited, must have been, at that time, above water, and, perhaps joined, at the south, to the ancient group which preceded the Pyrenees. The mountains of Maures also existed, and, perhaps, a part of the formations comprised between Toulon and Inspruck, in a south- west and north-east direction. Some parts of the 'centre of Vosges, and of the Black Forest, Eiffel, the Hundsruck, where the first upheaval is clearly indicated, and Ardennes, were necessarily above water, as well as the county of Nassau, the Hartz, all the centre of Germany, including Saxony, Bohemia, and Moravia. The same i? true of Scandinavia, and a part of the British islands. COAL EPOCH. 193 From this moment lands were covered with vegetation, in arbo- rescent ferns, equisita'cese, &c., sufficiently abundant to form the masses of anthracite found in the Devonian formation. The seas were then inhabited by trilobites, orthoce'ratites, orthis, productus, different kinds of terebra'tula and several species of polypa'ria, of the same genus as those found in madreporic reefs, which, as well as the tree-ferns, indicate a climate analogous to that of the present tropics. All these circumstances show that heat was not, in that epoch, distributed over the surface of the globe as it now is. Without doubt, the increase of temperature, from the surface to the interior, was more rapid ; all springs were warm ; and, according to M. Elie de Beaumont, the fogs, which were the result, hinder- ing radiation, in the absence of the sun, everywhere tempered the rigour of winter, and thereby augmented the mean temperature of the seasons. Coal epoch. The upheaval of the Ballons, in bringing " to day" the Silurian and Devonian deposits, no doubt, increased the extent of lands, and more or less changed their configuration. Vegeta- tion must have been prodigiously developed, at that time, and over vast surfaces ; which is proved by the enormous mass of coal formed, and the manner in which the deposits are piled up. On one hand, the carboni'ferous limestone, and the different marine beds found in the midst of the sandstone of the coal formation itself, seem to indicate at first a deep sea, and perhaps afterwards an immense maritime marsh, which extended from Ardennes and the Hartz to the ancient mountains of the British islands. On the other hand, the numerous coal basins known to exist in the surface of France and central Germany, clearly show there were extensive lands on which marshes were found, here and there, in which were formed, just as pcat-bogs are in our times, all the coal deposits we have discovered. The ancient and uncovered formations, which constitute Brittany and the central plateau of France, clearly indicate high land, on which are found the lakes of Bayeux, duimper, Laval, and Vouvant, placed perhaps in the anfractuosities caused by upheaval of the ballons ; then those of Buro-undy, Limousin, Auvergne, Forez, &c., situated on a direction parallel to the elevation of the Hundsruck. This land, the limits of which cannot be fixed, extended at least to a peninsula towards Strasburg. To the east of this land, and perhaps united to it, there is another, which was evidently uncovered, because there is nothing of the penine formation deposited on it. The latter probably extended over the space no\v occupied by Inspruck, Milan, Briancon, Genes, Nice, Toulon, and to the island of Corsica. Towards Toulon are the marshes in which was formed the coal now found in that part of France. Lands also evidently existed over the space occupied by Bohe- 17 194 COAL EPOCH. mia and Saxony, with several coal lakes on their surface ; the coal deposits of Moravia and Galicia seem to show their extension towards those countries. There was one island, at least, between Cologne and Francfort, presenting in its southern part the great coal basin of the country of Treves, and uniting, at the north, with the ancient formation of the Hartz. Dry land also existed in the peninsula of Scandinavia, where nothing has been deposited since the Silurian formations ; but it seems to have been sterile, and without swamps, for it affords no trace of coal. We are entirely ignorant of what existed where the great cities now stand; but the absence of carboniferous limestone, out of Bel- gium and England, may lead us to think that a great portion of western Europe w.as then uncovered, and perhaps presented coal^ lakes which subsequent catastrophes have sunk beneath the seas. A part of the land just mentioned has always remained unco- vered to the present time, or has been even upheaved more and more by various subsequent catastrophes, as Brittany and the cen- tral plateau of France. At certain points, in fact, coal deposits have been pushed upwards to a great height, as the plateau of Santa Fe de Bogota, and in the Cordillera of Huarochiri, where some are found from 2700 to 4000 yards above the sea. In other places, on the contrary, it is evident the formations have sunk, to be covered by more modem deposits, through which the coal is sought in the depth, as at Anzin, under the chalk, in Vosges, under the red sandstone, in Cevennes, under the jura'ssic limestone, &c., and, in general, on the borders of new formations exposed by sub- sequent catastrophes. Without doubt, there is some deeply-buried, and for ever lost to us, either under different sediments, or under water, as at Whitehaven, in England, where the mine extends more than a quarter of a league from the shore, and a hundred yards beneath the bottom of the sea. The vegetation of this epoch, favoured, no doubt, by the insular form of the land, as it now is in all islands, consisted of lycopodia'- ceas, equisita'cese, ferns, &c., of arborescent species, the analogues of which nre no longer found except within the tropics, with com-, fers resembling the araucaria. The mass of coal was formed of their debris, with cellular cryptoga'mia, which then grew under water, as now, in peat-marshes, and under a still more favourable temperature for their development. The seas of this epoch had lost their tri'lobites ; but contained, in great abundance, spi'rifers, productus, orthoceras of particular species, different ce'phalopods, analogous to the nautilus and argo- naut, and various other shells. The encri'nites were so extensively multiplied that their debris constitute, almost of themselves, certain varieties of Flemish and Belgian marble. Sauroid fishes, of great size, and of especially vigorous organization, then existed ; and the family of sharks, still feeble, presented cestra'cions and hybo- dons (Jigs. 52, 53, p. 45). THE PENEAN AND VOSGEAN EPOCHS. 195 The fresh waters which fed the coal marshes contained, as it appears, few conchi'ferous mollusks ; the debris, which are rarely found, resemble anodonta and unio'. Fishes were numerous, in some localities ; they belonged to the. genera palioni'scus (fig* 56, p. 48), and ambly'pterus, living, without doubt, in the rivulets which meandered at the bottom of abrupt fractures of the ancient formation. Penine epoch. The disturbance caused by the upheaval of the north of England, appears to have exerted more influence on the surface, of the then uncovered lands, than on their extent and form. Only the bottom of the sea, where the coal-beds of Eng- land and Belgium were formed, was elevated in part to escape, like all France, to the penine formation. On the other hand, a small corner of the south-west of Vosges must have sunk under water, to receive the red sandstones which there cover the coal formation. Further, in Mansfield the presence of the penine formation, which is there developed on a great scale with its shell-limestones, demonstrate the submersion of the country beneath sea-water. It was also beneath the sea, in the county of York, that magnesian limestone was deposited, which there repre- sents the whole formation of this epoch. Very little is known of the terrestrial flora of that time, for we find little, save the algae in the bitu'minous schists of Mansfield, and some sili'cified trunks of co'nifers in the sandstone. Deposits of coal suddenly ceased to form, and it seems from that time there were neither ponds nor rivulets on the lands ; nevertheless, there were still divers fishes of the genus palioni'scus, which lived per- haps as well in salt as in fresh water. The land was for the first time inhabited by saurian reptiles resembling the iguana and moni- tor, the remains of which are found in the cuprous schists. The seas beneath which all these deposits were formed, contained the same genera, often the same species of mollusks and radiata as those in which the carboni'ferous deposits were formed. Vosgean epoch. The system of Hainault, in dislocating the coal formation and ridging the surface of the land, had little in- fluence on its form. In the Vosges some of the points where the red sandstone was deposited were elevated, around Saint-Die, Schelestadt, Montbelliard, and escaped the succeeding formations ; while all the rest of the chain, which had escaped the deposits of the red sandstone, and consequently found elevated at this epoch, must have been sunk now to receive the vosgean sandstone : the same has taken place in the Black Forest. Such was the state of things in this modification, that animals could not have lived on this part of the earth, and that plants, if any then existed on the surrounding soil, could not have been car- ried under the waters except in very small numbers. The trias epoch. After the system of the Rhine, subsequent to 196 THE TRIAS AND JURASSIC EPOCHS. which the vosgean sandstone was upheaved, Vpsges and the Black Forest underwent a little change in shape ; but other lands in Europe have undergone scarcely any modification. We observe only a secondary elevation of the central plateau of France by the porphyroid granites of Lozere, by the hills which edge the coal formation from Fins to Mauriac. Subsidences occurred, on the other hand, in Bourbonnais and Rouergue, as well as in lands be- tween Toulon and Mice. Vegetation then underwent great modifi- cations ; the ferns and equisita'cerc of great height had considera- bly diminished, and coni'fers, on the contrary, became more numerous : plants analogous to za'mia, and perhaps to cy'cas (Jigs. 305, 306),- then formed an important part of the flora of Europe, being a prelude to the immense development they took in the succeeding epoch. Fig. 305. Za'mia pungens. Fig. 30fi. Cy'cas revoluta. In this epoch new saurians appeared, and traces of birds, which had not appeared in preceding epochs, are recognised. It was at this period also that those creatures existed, whatever they were, whose tracks are found imprinted on bunter sandstein, freshly lifted above water. Mr. Owen, who considers them enormous batrachians, supposes them to have been of the form represented (Jig. 307). The jum'ssic epoch. At the time of the elevation of Thurin- gerwald the tria'ssic formation, which had just been deposited beneath the sea, was upheaved at different points; some patches of banter sandstein were added around the central plateau of France, between Moulins and La Chatre, between Brives and Tulle, in the environs of Rodez, of Saint-Affrique and of Lodeve. THE JURA'SSIC EPOCH. 197 Fig. 307. Labyrinthodon pachygnatus. (Owen.) The island of Var was increased from these sandstones and con- ch ylian limestone ; the Vosges and Black Forest were also con- siderably augmented, the one to the west, in Lorraine, the other to the east, extending into Germany, and uniting various islands which had been separate till then. The same was the case with different islets which already marked the place of the British islands, and were then united to a continuous land by tria'ssic depo- sits upheaved between them, and with them. But at the same time that the new lands were raised above water, there were great subsidences in those which previously existed. The land which extended from Cherbourg to Perpignan, was then divided towards Poictiers, forming a strait, now occupied by the jura'ssic deposits ; it was variously divided on its borders, and almost cut again towards Rodcz. That which extended from Nice towards Inspruck was entirely sunk, to receive the new deposit which covers it. If per- chance there existed, at the period of the coal, some portions of land where Paris, London, &c., now are, everything leads to the belief that they then disappeared, for the jura'ssic formation appears to be prolonged everywhere beneath the soil which serves them as a base. All the data on the state of western Europe, at the period of which we speak, are furnished by the presence and disposition of the jura'ssic deposits. Developed on a vast scale, and upheaved later from the bosom of the waters, they clearly show what was then the configuration of the lands around which they were formed under the sea. The ocean of the jura'ssic epoch also had its peculiar characters. It was inhabited by saurians, eminently swimmers, the ich'thyo- sau'rus and plei'siosau'rus, whose paws, in form of paddles, remind us of those of the chelonians of the present day ; these voracious animals, all aquatic, took the place of the sauroid fishes of the car- boni'ferous group, which had now disappeared. At the same period lived those flying saurians, called pteroda'ctyls, which peopled the air and completed the series of singular creatures of an ancient creation, now entirely annihilated, the exterior forms of which Dr. Buckland has attempted to paint from the skeleton (fig. 308). These seas had lost the productus, and spirifers had almost dis- 17* THE JURA'SSIC EPOCH. Fig. 308. Restoration of the saurians of the jura'ssic epoch. appeared. The numerous terebra'tulee, which lived in this epoch, belonged to species entirely different from those seen in the pre- ceding seas ; but there was found a great number of mollusks with chambered shells, in general called ammonites, the race of which, as yet little developed, had begun to appear in the seas of the trias ; there existed bele'mnites, the remains of which, until then unknown, are numerous from the lias to the chalk : and the gry'phea arena' ta multiplied there for a moment, to disappear afterwards, when the has was formed, and to give place to other species of the same genus. As at present, coral reefs were formed in those seas, remains of which are found, showing a mean temperature, analogous to that of our intertropic seas. On the land, fresh-water lakes without doubt supported palu'di- na3, and fresh-water streams carried helices, remains of which are now found in the Portland group. There must have existed also, on land, several species of insects, which served to feed the pteroda'ctyls, the remains of which seem to show they were coleoptera and neuroptera, resembling the bu- prestes and libe'llulse. Small marsupial mammals, analogous to opossums, were met there, a skeleton of which was found in the beds of Stonesfield. But these creatures seem to have been in small numbers, if w r e judge from the few remains that have been as yet found, and no one of the great animals which characterize the parisian epoch has been found with them. CKETA'CEOUS EPOCH. HMJ The flora was not the same as that which furnished so many remains to the coal formation ; the lycopodia'ceae, and the gigantic ferns had disappeared ; and it seems that many new species had been created after the penine and tria'ssic epochs. Then the cyca'dese and co'nifers considerably exceeded all other families ; and probably some palms were already in existence, the fruits of which are found in the lias. Also the carbona'ceous combustible, formed in this epoch, is very different from that of the great coal formation. They were at the same time much less abundant, which indicates a great difference in the extent of lands. Creta'ceous epoch. After the system of upheaval of Cote-d'Or, which elevated a part of the jura'ssic deposits above the sea, the form and disposition of continents were considerably changed. The inferior limits of the chalk mark the shape of lands which then existed, and determine the extent of the seas of the epoch. The three islands of the preceding epoch were now united, but without any change of shape. Brussels, which was inland, was now found on the coast ; Arras, Dunkirk, Maastricht, Wesel, Bres- law, and Vienna, were sunk under water. A lake was formed between Dresden, Brunna, and Prague ; a strait was found in the place of Perpignan and Carcasonne ; and, what existed previously to the Pyrenees, was in part submerged. By compensation, the Vosges, washed by the sea in preceding ages, was then found in the middle of the continent which joined the central island of France. The space of sea which separated them was filled up. Langres, Nevers, Lyons, Toulouse, and Ox- ford, were on terra fir ma, and an isthmus was formed about Poic- tiers, to join the great island that existed to the west. A shore extended from the environs of Craco'via, to about Perpignan, by Ratisbonne, the position of which was not changed, and to Zurich and Lyons. An immense gulf was formed between Brussels and Oxford, extending to Poictiers. Between Salzbourg and Avignon, a new island was formed, which marked the future site of the Alps : Brian^on, Turin, Trente, and Inspruck, might have been already placed there ; but Switzer- land was then a channel which separated this island from terra firma. The island of Toulon was at the time limited, and some small islands marked the environs of Marseilles. Little change, however, had taken place in living creatures. At the same time divers species of ferns and cyca'dese vegetated on the soil ; co'nifers, especially, became more and more abundant, and gave origin to masses of lignite found at the base of the chalky formations ; but there were few terrestrial mammals, for no remains of them are found in the chalk, although they were met with in jura'ssic deposits. There existed, however, divers ceta'cese, such as lamantins and dolphins, some of which had already appeared in the jura'ssic seas. Reptiles were, among the animals capable of 200 PARISIAN EPOCH. living on the earth, still the most elevated creatures of the creation. Aquatic and terrestrial species were very numerous ; among them were the iguanodon, the megalosau'rus, and divers crocodiles. Fluviatile tortoises, fishes, and mollusks of fresh water, lived on the borders of lakes, or in their waters. The seas fed ba'culites and turriiites, of whose anterior existence there is no trace, and which, towards the end of the epoch, disappeared at the same time with all mollusks having peculiar chambered shells. Here and there true sharks existed, and have been continued to the present time, although their dimensions are considerably diminished. Parisian epoch. The upheaval of Mount Viso, and later, that which gave birth to the Pyrenees, to the Apennines, and all the parallel chains we have cited, prodigiously changed the geographi- cal constitution previously established. The last, especially, pro- duced one of the greatest convulsions Europe has experienced : everything was shaken by it, and the greatest part of what was then under water, was elevated above it, to form an immense con- tinent. This proves the little extension of the parisian sediments then formed, and which are found concentrated, one part in Bel- gium, Artois, Picardy, Isle of France, Normandy, and the opposite coasts of England ; and the other, in the environs of Bordeaux : very few traces are found elsewhere. Hence it follows, that the seas of this formation did not penetrate far into this continent, although they covered the two capitals of the world ; of the vast ocean of preceding ages there only remained a part of the gulf already limited, about Cambridge, Oxford, Exeter, Cherbourg, Angers and Poictiers, which was then narrowed in many places, and widened elsewhere at the expense of the ancient peninsula of Brussels ; it probably communicated with some remains of the North Sea. In the middle were two islands of chalk, the Wealds, of England, and the country of Bray, in France. Another portion of the gulf also remained between Bordeaux and Dax. The fauna of the land, at the parisian epoch, was very different from what it had been in preceding epochs. The gigantic sau- rians had disappeared, but there remained great fresh-water cro- codiles, marine and lacu'strine chelonians, and the earth was inhabited by mammals. The last were then pach'yderms, analogous to tapirs, as the anoplothe'rium and paleothe'rium, which must have been nearly of the form represented (fig. 309) ; they lived at the same time with some carni'vora of the genus dog, &c. Belem- nites, and all similarly chambered shells, had disappeared from the seas ; the nautilus only remained, and it lived with the cere'- thium giga'nteum (fig. 148, p. 80), and a multitude of species of rnollusk, more or less resembling those of existing seas. At this age of our planet, the flora of Europe was still modified ; the cyca'dea? had disappeared, and the co'nifers, presenting still new species, to which were joined the dicotyledons, were found, PARISIAN EPOCH. MQLA6SE. 201 a b d Fig. 309. Fauna of the epoch of the parisian formation. ileothe'rinin ma*ojDEaMs fr. gr. echinos, a 220 GLOSSARY. GEOLOGY. hedge-hog, derma, skin. A class of invertebrate animals, with a crus- ta'ceous integument armed with tu- bercles or spines (p. 52). EDENTA'TA Edentate. An order of mammals without teeth. EDE'NTATE fr. lat. e, without, dens, tooth. Without teeth. EFFERVE'SCEITCE fr. lat. effervesco, I grow hot. The commotion pro- duced in fluids by the sudden escape of gas in the form of bubbles.^ EFFU'SION fr. lat. effundo, I pour out. The pouring out of a liquid. E'LEGANS Lat. Elegant. EMBOSS fr. fr. bo&se, a protuber- ance. To cover with lumps or bunches. ENCRI'NITES fr. gr. krinon, a lily. A genus of echi'noderms (p. 52). E'NTOMO'STRACANS fr. gr. ento- mos, incised, ostrakon, a shell. A division of the class of crust a'cea. E'OCE'NE (p. 78). EPIDEMIC fr. gr. epi, upon, de- mos, the people. A prevailing dis- E'pocH The time from which dates are numbered. E'POCH OF FORMATION (p. 192). EQ.UA'I-IS Lat. Equal. EatrA'TioN fr. lat. sequare, to equal. Equivalent. A mean proportion between extremes. Eauin'BRiUM fr. lat. segue, equal- ly, libra, I balance. Equal balance. EQ.UISE'TA Plur. equisetum. EOTTISETA'CE^ fr. equise'tttm, one of the genera. A natural order of plants. EQ.UISE'TUM fr. lat. eguus, horse, seta, hair. A genus of plants. ERO'DE fr. lat. erodo, I gnaw. To wear away, to corrode. ERO'SION The act of wearing away. ERO'SIVE Corroding, wearing. ERRATIC BLOCK FORMATION (p. 93). ERU'PTIOST fr. lat. e, from, rumpo, I burst. The act of bursting from any confinement. ESCA'BPMJENT fr. it. scarpa, sharp, formed fr. lat. carpere, to cut or divide. The steep face often pre- sented by the abrupt termination of strata where subjacent beds " crop out" from under them. ESCHAROIDES fr. gr. eschoro, a fire-place, a gridiron, eidos, resem- blance. Specific name of a coral (p. 31). EUOM'PHALTJS (p. 39). EU'PHOTIDE A rock composed essen- tially of feldspar and diallage. EVOLU'TTJS Lat. Unfolded. EXCORIA'TION fr. lat. ex, from, curium, skin. An abrasion, mark of a part having been rubbed from the surface. EXO'GYBA fr. gr. exo, without, gu- ros, circle. Not circular. (Figs. 109, 115, 125, 135.) A genus of unimuscular bivalves, allied to the oyster. EXPLOSION A sudden bursting with noise and violence. EXTREMITIES The limbs ; legs, arms, &c. EXUDA'TIOST fr. lat. ex, from, sudo y I sweat. Transpiration. Exu'vi-E Lat. The sloughs or cast- skins, or shells of animals. FASCI'CUI.IS Lat. Plur.of fasciculus. FASCI'CUI.US Lat. A bundle. FASTIGIA'TA Lat. Sharpened at top like a pyramid. FATHOM A measure of six feet. FAULT fr. ger. fall, an accident, sinking, fall (p. 158). FAU'NA fr. lat. faunus, the name of a rural deity among the Romans. All animals of all kinds peculiar to a country constitute the fauna of that country. FECIT Lat. He made. FELD'SPAR, OR FELSPAR fr. ger. feldspath. An important mineral composed of si'lica, alu'mina, and potash, with traces of lime, and often of oxide of iron. It enters into the composition of granite. FELDSPA'THIC Of the nature t or be- longing to feldspar. FELIS Lat. A cat. GLOSSARY. GEOLOGY. Specific name of a fossil zamia (p. 65). FEHRTJ'GIKOUS fr. lat/errwm, iron. Containing iron. FICOI'DES fr. lat flcus, a fig-tree, and gr. eidos, resemblance. Speci- fic name of a fossil plant FIRMAMK'XTUM Lat. The firma- ment. FIS'SILE fr, lat flndo, I split. Easily split FIS'SURE A crack, a separation ; a split FLO'RA fr. lat flora, goddess of flowers. All the plants of all kinds of a country constitute the flora, of that country. FLU'VIATILE Belonging or relating to a river. FOLIA'CEA Lat. Foliated. FOLIA'TED fr. lat folium, a leaf. In form of leaves ; leafy. FORAMISTI'FERA fr. lat. foramen, hole,yero, I bear. Name of a tribe of minute shells. FORMA'TIOK Any group of rocks formed during a particular epoch, or of common origin. Fos'sii, fr. [at.fodio, I dig. Any organic body, or the traces of anj r organic body, whether animal or vegetable, which has been buried in the earth by natural causes (p. 21). FOSSILI'FEROUS Containing fossils. FOS'SILIZED Converted into a fos- sil. FU'LCRUM Lat. A prop. The fixed point on which a lever moves. FUM'AHOLE Fr. Subterraneous emis- sion of hydrogen gas in consequence of the ebullition of certain sulphu- rous waters. The hole or orifice through which the gas escapes. FUMES Vapours. FUSION The act of melting ^ state of fusion, is being melted. FU'SIFORHE' Lat Fusimorm, spin- dle-shaped. GALE'XA fr. gr. galene, lead-ore. Sulphuret of lead, that is a com- pound of sulphur and lead. 19* GANOIDEAXS An order of fishes (p. 48). GA'RNET A mineral consisting of silicates of alu'mina, lime, iron, and manganese. There are several va- rieties of this mineral. Garnet oc- curs imbedded in mica slate, granite, and gneiss, and occasionally in limestone, chlorite slate, serpentine, and lava. GAS fr, ger. geist, spirit. The name given to all permanently elas- tic fluids or airs different from the atmospheric air. GA'SEOUS Of the nature of gas. GAULT A kind of clay (p. 71), GELA'TIITOUS Jelly-like. GE'X ERA Lat Plur. of genus. GENE'RIC Relating to genus. GE'UUS Lat. A kindred, breed, race or family. GE'ODES fr. gr, geodes, earthy. Nodules of iron stone, hollow in the centre. Rounded pebbles hav- ing an internal cavity, lined with crystals, are also so called. GE'OGENT fr, gr, ge, the earth, gei- nomai, I beget. Science embracing the theories of the formation of the entire universe. GEOGNO'STIC Relating to geognosy. GEOG'NOSY fr. gr. ge, the earth, gnosis, knowledge. Knowledge of the mineral substances which con- stitute the mountains and strata of the earth. GEOLO'GICAL Relating to geology. GE'OLOGIST One skilled in geology. GE'OLOGT fr. gr. ge, the earth, lo- gos, discourse. That branch of natural history, which treats of the structure of the terrestrial globe. It is divided into descriptive geology? dyna'mic geology, which treats of the forces by which the surface of the earth has been modified ; prac- tical and economic geology, em- bracing the application of geological science to mining, road-making, architecture, and agriculture. GEY'SERS From an Icelandic word signifying raging or roaring. Cele- 222 GLOSSARY. GEOLOGY. brated spouting fountains of boiling water in Iceland (p. 136). GIBBO'SITY fr. lat. gibba, a bunch. A protuberance. GIGA'NTEUM GLABER Lat. Smooth, bald, bare. GIA'CIERS Fr. Masses or beds of ice formed in high mountains, de- rived from the snows or lakes frozen by the continued cold of those re- gions (p. 150). GLOBA'TA. Lat. Globate, rounded. GNEISS Ger. A rock resembling granite in its constitution and ge- neral characters ; but it contains more mica and the colours are banded, but owing to the arrange- ment of the minerals, especially the mica, in parallel planes. In con- sequence of this structure the rock splits into coarse slabs, along the planes of the mica, besides having the cross fracture or cleavage of granite. It is often described as a stratified or stratiform granite. A rock intermediate between granite and gneiss is called gneissoid gra- nite. Gneiss is used for building and flagging" (p. 25). GON'IATITES (p. 38). GOODHALLII The name Goodhall latinized. GRA'LLEJE Lat. Wading-birds. GRA'NITE A crystalline aggregate of quartz, feldspar, and mica. The ingredients of granite vary in their proportions, and the rock is described as mica'ceous, feldspathic or quartzose, according as mica, feldspar, or quartz is the, predo- minating mineral. It is called Por- phyritic granite when the feldspar is uniformly disseminated in large crystals ; they appear like white blotches, often of a rectangular shape, over a worn surface of the rock. GHANI'TIC Belonging or relating to granite. GRA'NTJLAR Consisting of grains. GKA'PHITE fr. gr. grapho, I write. A mineral composed of carbon and 1 iron, constituting carburet of iron. It is known as plumbago and black lead,- it is used in the manufac- ture of lead-pencils. GRAU'WACKE, and GRATWACKE Ger. Grey rock. A name given to some of the older shales in the geological series, and also to the sandstones that accompany them. GRA'VEL Small rounded stones vary- ing in size from a small pea to a walnut, or something larger. GRAVITATE - fr. lat. grams, heavy, To tend towards the centre of the earth, as ail bodies do from their weight. GREENSAND A formation of the cre- ta'ceous group (p. 70). GREENSTONE A tough variety of trap-rock, consisting chiefly of horn- blende. GRE'S BIGARRE' Fr. A fine-grained solid sandstone, sometimes white, but more frequently of a red, blue, or greenish colour. It is the same as bunter sandstein. GRIT A coarse-grained sandstone. GRUNDSTEIN Ger. Greenstone or diorite. GRY'PHEA fr. gr. grupos, incurved. A genus of fossil bivalves. GRT'PHITES Generic synonym of the productus aculeatus (p. 49). GRY'PHITE LIMESTONE A marl, so called from containing gry'phea. GRY'PHITENKAIK Ger. A name sometimes given to zechstein (p. 49). GYMNOSPE'RMOUS fr. gr. gurnnos, naked, sperma, seed. Having naked seeds. GY'PSEOUS Of the nature of gypsum. GT'PSUM (jVp-suw). Native sul- phate of lime. The transparent varieties constitute se/enite, and the fine massive Alabaster. Gy'psum is converted into plaster of Paris by heat. KA'MITES fr. lat. hamus, a hook. A genus of extinct cephalopods, inhabiting chambered shells, losing their spiral form after their com- GLOSSARY. GEOLOGY. 223 mencement, and then continued for a considerable extent with a single bend on themselves like a hook. They are found in the greensand of England. HE'LICES Plur. of helix. HE'LIX Lat. A snail. HE'TEROCERCAL fr. gr. 'eteros, op- posite, kerkos, a tail. Having the spine prolonged into the tail (p. 49). HETERO'PHTLLA fr. gr. 'eteros, op- posite, phullon, leaf. Specific name of a fossil plant (p. 53). HIBBERTI Name of Hibbert la- tinized. HIEROGLY'PHICS- fr. gr. ieros, sa- cred, gluphd, I write. Sculpture or scripture writing. HI'PPUHITES fr. gr. ippouris, horse- tail : a certain fish. A genus of extinct mollusks, supposed to be bivalve. The principal valve is of a sub-cylindrical or elongated, co- nical form, traversed by one or more internal longitudinal ridges, and closed by a small sub-circular valve like an operculum (p. 68). HIPPOPO'TOMI Lat. Plur. of hippo- potamus. HIPPOPO'TAMUS fr. gr. 'ippos, horse, potamos, a river. The River-horse. HOLO'PTICUS, and HOLOPTT'CHIUS fr. gr. 0/05, the whole, ptuchios, folded. A fossil fish of the ganoid order, the enamelled surface of whose scales was marked by large undulating furrows. It had sharp conical teeth (p. 44). HO'MOCERCAL fr. gr. omos, joined, kerkos, a tail. Applied to the tail appended to the termination of the spine, as in most of the fishes now existing (p. 49). HO'RJTBLEWDE A mineral of dark green or black colour, abounding in oxide of iron, and entering into the composition of several of the trap rocks. There are three varie- ties ; common, hornblende-schist, and basaltic hornblende. HORNBLENDE-SCHIST A slaty varie- ty of hornblende. HU'MTJS Lat. Moist earth. Vege- table earth or mould. HI/MERITS Lat. Shoulder. Name of the bone placed between the shoulder and elbow. HT'BODOKS fr.gr.w6o5, bent out- wards, and odous, tooth. A divi- sion of the shark family (p. 44). HY'DRATED fr. gr. 'udor, water. Containing water. HYDROCHLORIC ACID An acid com- posed of hydrogen and chlorine, formerly known as muriatic acid. HYDHOSTA'TICS fr. gr. 'uddr, wa- ter, stad, I stand. The scfence which explains the properties of the equi- librium and pressure of liquids. HY'PERSTHENE Labrador horn- blende. It contains iron, si'lica and magnesia. Hypersthene rock dif- fers from common hornblende only in its foliated crystallization and its pearly or metallic-pearly lustre. It is a very tough rock, with a struc- ture resembling gneiss. HYPNOIDES fr. gr. upnon, a sort of moss, eidos, resemblance. Speci- fic name of a fossil plant. HY'POGESTE fr. gr. upo, under, gei- nomai, I am formed. A class of rocks which have not assumed their present form and structure at the surface of the earth, but are appar- ently of igneous origin and thrust up from below. HYPO'THESIS fr. gr. upo, under, tithemi, I place. A theory, or sup- position. A rational conjecture. HYPO'THETICAL Of the nature of hypothesis. I'CHTHYOSAU'RUS The fish lizard (p. 57). IG'NEOUS fr. lat. ignis, fire. Re- lating or belonging to fire. IGUA'NODOX From iguana, and the Gr. odous, tooth. An extinct genus of gigantic herbivorous reptiles, dis- covered in the south of England. IMBRICATA'RIA Lat. As if imbri- cated, or tile-like. IMBRICA'TA Lat. Imbricate, tile- like. Arranged like tiles. S24 GLOSSARY. GEOLOGY. IMPRE'SSA Lat. Impressed, engrav- en, marked. INJEO.UIYA'LVIS Lat. Inequivalve. Having unequal valves. INCANDE'SCENCE fr. lat. incandes- cere, to grow very hot, to be in- flamed. The condition of great heat, showing a certain light, as if the heated substance itself were burning. Melted. INCANDE'SCENT Greatly heated. INCOHE'RENT fr. lat. in, not, con, with, hsereo y I adhere. Loose, want- ing cohesion. INCLINATION OF BEDS Dip (p. 185). INCRIJSTA'TION fr. lat. eras/a, a crust. A covering like a crust. INEQJJILA'TERAL fr. lat. insequalis, unequal, lotus, (in the genitive, lateris,} side. Having unequal sides. INFILTRATION fr. lat. Jiltrare, to filter. The act of filtering through, producing an accumulation of li- quid. INOCE'RAMUS fr. gr. en, with, ke- ramos, earthen ware? A genus of bivalve fossil shells, which are chief- ly characterised by their hinge and the fibrous structure of their con- stituent substance. The shell, in consequence of the vertical arrange- ment of the fibres, readily breaks to pieces, and it is often extremely dif- ficult to extricate a specimen with the hinge and beaks tolerably entire. IN PLACE In their original position where they were formed. INIUJINA'TA Lat Stained, dirty. INSERTED Attached. IN SITU Lat. In place. INTERCALATED fr. lat. intercalo, I place between. Placed between. INTERCALATION The placing one substance between others, as one stratum between two others. INTERPOSED fr. lat. inter, between, pono, I place. Placed between. INTERTIUMPICAL Between the tro- pics. [NTRUSION The act of thrusting or forcing in. I'SOLATED fr. it. wo/a, an island. Separated like an island. ISOTHE'RMAL fr. gr. isos, equal, therme, heat. Isothermal lines are those which pass through those points on the surface of the earth, at which the mean annual tempera- ture is the same. JA'SPER A siliceous mineral of vari- ous colours. JOINTS OF DISLOCATION (p. 187). JURA'SSIC Belonging to the Jura mountains. KEU'PER Ger. The upper portion of the new red sand-stone forma- tion (p. 52). KJMMKIU I<;K CLAY (p. 64). KlMMERIDGE COAL (p. 65). KU'PFERSCHI'EFER Ger. Copper- slate (p. 47). LA'BRADORITE Labrador spar. It consists of silicate of alu'mina, lime, and soda, with traces of oxide of iron. It is a variety of feldspar. LABTRI'NTIIICA Lat. Labyrinth- like. LABTRI'NTHODON fr. gr. laburin- thos, a labyrinth, odous, tooth. An extinct genus of batrachians, characterised by teeth of a peculiar- ly complicated structure. The re- mains of this genus peculiarly cha- racterise the Keuper formation in Germany and the corresponding sand-stones in England (p. 196, and Jig. 307). LACE'RTIAN fr. lat, lacerta, a lizard. Any animal of the lizard tribe. LACU'STRINE fr. lat. locus, a lake. Belonging or relating to lakes. L.KVIS Lat. Smooth, bare, bald. LAM ANO'NIS Specific name of a fos- sil plant. LAMBE'RTI The name of Lambert latinized. LA'MINA Lat. Plur. laminae. A plate. LANDSLIP or LANESLIDE. The re- moval of a portion of land down GLOSSARY. GEOLOGY. an inclined surface, from its at- tachment being lessened by the ac- tion of water beneath, or by an earthquake. LAPI'LLI fr. lat. lapillus, a little stone. Small volcanic cinders. LATERA'LIS Lat. Lateral. LA'VA The substances which flow in a melted state from a volcano. Lavas vary in consistence and tex- ture. LE'NTA Lat. Slow, heavy, stupid. LEPIDODE'NDBA Plur. of lepidoden- dron. LEPTDODE'NDBON fr. gr. lepis, scale, dendrun, a tree. A genus of fossil plants, having a scaly bark. LEPTE'NA A synonym of the genus productus (p. 30). LEYMERII The name Leymerie la- tinized. LIAS (p. 54). LI'GNEOUS fr. lat. lignum, wood. Woody ; of the nature of wood. LI'GNITE fr. lat. lignum, wood. A kind of coal. LI/MA Lat. A file. Name of a genus of bivalves. LINEA'RIS Lat. Linear, line-like. LINE OF BEARING Strike (p. 185). LIQUEFA'CTION The act of becoming liquid. LITHU'ITES and LITU'ITES fr. lat. lituus, a crooked staff. Fossil chambered shells, curved or bent at one end (Jig- 8). LITHOGHA'PHIC fr. gr. lithos, stone, grapho, I write. Lithographic stone, used for the purposes of lithography (p. 65). LITIIO'PHAGI fr. gr. lithos, stone, phago, I eat. Small worms found in slate which give it a red co- lour. LITTORA'LIS Lat. Littoral ; be- longing or relating to the shore. LOAM A mixture of sand and clay. LOHES Veins containing metallic ores. LOESS A German geological term, applied to a tertiary alluvial de- posit, which occurs in patches be- tween Cologne and Basle. The term is applied by the English to that peculiar yellow loam with cal- careous concretions. LONDON CLAY (p. 78). LONGIRO'STRIS lat. fr. longus, long, rostrum, beak. Long-billed. LONGISCA'TA Lat. A little longer. LT'COPO'DIA'CEJE fr. gr. lukos, a wolf, pous, foot. A natural order of plants which includes the ly'co- po'dium. LYELLH The name of Lyell la- tinized. LYMNE'A or IIMNEA fr. gr. lirnne, a pool. A genus of fresh-water snails. LU'CEM Lat. Light. LUGDITNENSIS Lat. Belonging or relating to Lyons. LUMACHELLA See note p. 67. MA'DREPO'RA Lat. Compound of the French madre, spotted, and Lat. porus, pore. A genus of corals (p. 141). MADREPORE A kind of coral. MADHEPO'RIC Of the nature of ma- drepore. MAGNE'SIA A white, tasteless earthy substance. MAGNE'SIAN Relating to, or con- taining magnesia. MAGNE'SIATC LIMESTONE Lime- stone which contains magnesia. An extensive series of beds lying above the coal measures. MAGNE'TIC Having properties of the magnet or load-stone. MAG'NUM Lat. Great. MAM'MAI. Any animal that suckles its young. MAMMALI'FEROTJS Containing mam- mals. MAMMI'LLARY fr. lat. mammilla, a little nipple. Studded over with small rounded projections. MAMMOTH An extinct species of elephant. MANTE'LLIA A genus of fossil cy- ca'deffi, named in honour of Mr. Mantell. MA'RGABETI'JERA fr. lat. marga- 226 GLOSSARY. GEOLOGY. ritum, a pearl, fero, I bear. Pearl- bearing. MARINE fr. lat. mare, the sea. Re- lating to the sea. MAUL Argillaceous carbonate of lime. There are several varieties of marl. MA'RSHII The name of Marsh la- tinized. MAHSU'PIAL fr. lat. marsupium, a pouch. Any animal having a pe- culiar pouch in front or on the ab- domen. MA'STODON fr. gr. mastos, a nipple, odous, tooth. A genus of extinct quadrupeds allied to the elephant. WA'TRTX Lat. The stony substance in which metallic ores and crystal- line minerals are imbedded. Gan- gue. MAXIMUM Lat. Greatest. MEANDRI'NA A genus of polyps. MEANDIUV'^E Plur. of meandrina. MEDICAGJ/XELA Specific name of a chara, a kind of fossil moss. MEDU'LLARY HATS fr. lat. medulla, marrow. The vertical plates of cel- lular tissue which radiate from the centre of the stem through the wood to the bark in exogynous plants. MEGALI'CHTH YS fr. gr. megas, great, ichthus, fish. An extinct genus of fishes, including species of great size. MEGA'LODON fr. gr. megas, great. odous, tooth. A genus of peculiar fossil bivalve shells. MEGALO'NYX fr. gr. megas, great, onux, a claw. A large fossil mam- mal, found in Virginia. MEGALOSAU'RUS (p. 58). MEGATHE'KIUM (p. 92). MELA'NIA fr. gr. melas, black. A genus of fluviatile univalves. MELA'PHYRY, and MELA'PHYRE fr. gr. melas, black. A kind of por- phyry the constituents of which are united by a black cement (p. 173). MEPHIT'IC fr. mephitis, the goddess of foul smells. Applied to impure or foul exhalations. L] 'FZUOVS Containing metal. METAMO'RPHIC Relating to meta- morphism. METAMO'RPHISM fr. gr. rueta, indi- cating change, morphe, form (p. 177). METAMO'RPHOSES Plur. of metamor- phosis. METAMORPHOSIS Change of form. MI'CA fr. lat. mico, I shine. A mineral generally found in thin elastic laminae, soft, smooth and of various colours and degrees of transparency. It is one of the con- stituents of granite. MICA'CEOUS Of the nature of mica. MICA-SCHIST Mica-slate (p. 25). MI'CROSCOPE fr. gr. mikros, little, skoped, I view. An optical instru- ment which enables us to examine objects too small to be seen by the unassisted eye. MI'CROSCOPIC Minu'te ; perceivable only by aid of a microscope. MI'LLIOLITES, or MILI'OLA fr. lat. milium, a millet seed, and gr. lithos, stone. A genus of foramini'ferous fossil shells found in the neighbor- hood of Paris. MILLSTONE GRIT Coarse grained, quartzose sandstone. MINE Ger. Any subterraneous work or excavation which has for its ob- ject the extraction of any mineral products, as metallic ores, coal, &c. MINERAL Any inorganic natural object, whether solid, liquid or gas- eous. MINERALOGY That branch of na- tural science which treats of the properties of minerals. MINIMA } r i T MI'NIMUM $ Lat ' Least ' MINUS Lat. Little. MINU'TA Lat. Minute, very small. MI'OCENE (p. 78 and 83). MODERN FORMATION (p. 95). ! MOLA'SSE Fr. A fine grained sand- stone, usually soft and loose, but sometimes sufficiently hard for building purposes. MOLLUSK fr. lat. mollis, soft. Any animal of the class of mollusca. GLOSSARY GEOLOGY. 227 MONI'LE Lat. Belonging or relat- ing to a necklace. MONILEFO'RMIS lat. fr. monile, a necklace, forma, form. In form of a necklace. MO'XOCOTY'LEDONS fr. gr. tnonos, single, kotuledon, seed-lobe. A class of plants having but one seed- lobe in the embryo. MORAI'NES Longitudinal deposits of stony detritus found at the bases, and along the edges of all the great glaciers (p. 131). MOSASAU'RUS (p. 75). MUCRONA'TUS Lat. Pointed, sharp- pointed. MCLTILO'CULAR fr. lat. multus, many, loculus, a partition. Hav- ing many chambers or partitions. MTJ'RAL fr. lat. murus, a wall. Be- longing or relating to a wall. MTJ'REX Lat. A shell fish. A genus of univalve mollusks. MURICA'TA Lat. Full of sharp prickles or points. MU'SCHELKALK Ger. (p. 50). MTTSCLE An organ of motion ; the flesh of animals. MTJ'SSEI, A bivalve mollusk. MUTA'BILE' Lat. Mutable, change- able. MT'A A genus of bivalve mollusks. NA'GELFLTJE Ger. A coarse con- glomerate. . NATJ'TILUS A genus of cephalopods. NAVI'CTJLA Lat. A little boat. NEOCO'MIAN and NEOCOMIEN Fr. The lower beds of the cretaceous system in the south of France and elsewhere, are described by the French geologists under this name. NEPTUNIAN From Neptune, god of the sea. Belonging or relating to water, NERI'NEA A genus of fossil uni- valves, resembling both Cere'thium and Turritella (p. 63). NERVCRES Veins of leaves. Also, the tubes for expanding the wings of insects. NEURO'PTERA fr.gr. neuron, a nerve pteron, wing. An order of insects NEURO'PTERIS A genus of fossil plants (p. 41). NEW RED SAND-STONE (p. 47). NIDIFO'HMIS Lat. In form of a bird's nest. NILSO'NIA A genus of fossil plants. NODO'SUS Lat. Knotty. NO'DTTI.E fr. lat. nodus, a knot. A rounded irregular lump or mass. NOR'MAL fr. lat. norma, a rule. Ac- cording to the peculiarities of a family or genus, without the least departure. NORWICH, or NORFOLK CRAG A tertiary formation which rests on the London clay or chalk, and in- cludes marine shells (p. 84). NU'CLEUS Lat. A kernel. The solid core of a body. NU'CULA fr. lat. nux, a nut. A genus of bivalve shells with nume- rous teeth like those of a comb. NUMMULI'TES fr. lat. nummus, money, and fr. gr. lithos, stone. Fossil money. An extinct genus of cephalopods, of a thin lenticular shape, divided internally into small chambers. Nummulite limestone obtains its name from the presence in it of these shells in great abund- ance. In Alabama there is a moun- tain range entirely composed of one species of nummulite. NOTRI'TION The animal function by which the various organs receive nutritive substances (previously pre- pared by the several organs of di- gestion), necessary to repair their losses and maintain their strength. OBLO'NGUS Lat. Oblong. OBOVA'TA Lat. Obovate. OBO'YATE fr. lat. ob, for, opposite, ovum, egg. Reverse of ovate or egg-shaped. OBSI'DIAN Named after Obsidius. A glassy lava. Volcanic glass. It consists of si'lica and alu'mina with a little potash and oxide of iron. OCTOPLICA'TA Lat. octo, eight, pli- ca'ta, folded. Having eight folds. OLD RED SANDSTONE (p. 37). O'OLITE fr. gr. 00/2, an egg, lithos, 228 GLOSSARY. G EC stone. A granular variety of car- bonate of lime, frequently called roeslone (p. 58). O'oLixic Belonging or relating lo o'olite. OpALE'scEirr Resembling o'pal, a beautiful mineral, characterized by its iridescent reflection of light. OPE'RCULUM fr. lat. operio, I cover. The lid which protects the gills of fishes, and closes the opening of certain univalve shells. ORBICULA'RIS Lat. Orbicular. ORBIT fr. lat. orbis, a circle. The circular cavities in which the or- gans of vision are lodged, are named the orbits. ORES fr. ger. erzc. Mineral bodies from which metals are extracted. ORGAIT fr. gr. organon, an instru- ment. Part of an organized being, destined to perform some particular function ; the ears are organs of hearing, the muscles organs of mo- tion, &c. ORGA'XIC Relating to organs. ORGANIZED Possessing organs. ORGAifizA'Tioir A mode of struc- ture. OHGA'JTISANS Lat. fr.gr. organoo, I arrange, or provide with organs. Organizing, constructing. ORTHTS A genus of fossil bivalve shells (p. 29). OHTHOCE'RAS "> . _ ORTHO'CERATITE j O dS > OSCILLA'TIOX fr. lat. oscillum, an image, hung on ropes and swung up and down in the air. The act of moving backwards and forwards like a pendulum. OSCILLA'TORY Swinging backwards and forwards like a pendulum. OSTRA'CEA Family of bivalves which includes the oyster. OS'TREA Genus of bivalves ; an oyster. OUTCROP The emergence of a rock, in place, at the surface. OUTLIER A hill or range of strata occurring at some distance from the general mass 01 formation to which it belongs. OVA'TUS Lat. Ovate, egg-shaped. OVERLYING When one stratum lies over, or overlaps another, it is said to be overlying. OXFORD CLAY (p. 62). O'XIDE fr. gr. oxus, acid, eidos, form. A compound, which is not acid, containing oxygen. O'xYGEtf fr. gr. oxus, acid, gennein, to generate. Vital air. PA'CHYDE'RMA Lat. fr. gr. pachus, think, derma, skin. Thick-skin- ned. PA'CHYDE'RMATA Lat. Pa'chy- de'rms. PACHYUE'RMS An order of quadru- peds, including the elephant, horse, pig, &c., distinguished by the thick- ness of their hides. PA'CHYDE'RMATOUS Relating to pa'- chyde'rms. PA'CHYGJTA'TUS Lat. fr. gr. pachus, thick, gnathos, jaw. Specific name of the labyrinthodon (p. 197). PAL^OXI'SCUS (p. 48). PA'LJEOXTO'LOGIST One skilled in paleontology. PALJEOXTO'LOGY fr. gr. palaios, an- cient, on, creature, logos, a dis- course. That branch of zo'ological science which treats of fossil organic remains. PALJE'OZOIC fr. gr, palaios, ancient, zoe, life. Relating to ancient life. PALEOTHE'RIUM (p. 83). PALMACI'TES A genus of fossil plants. PALUDI'NA fr. lat. palus, a marsh. A genus of fresh water gasteropods. PALUDI'ITE Plur. of paludina. PALUDINE Belonging to a marsh. PARALLEL Extended in the same direction and preserving always the same distance. PARALLE'LISM The state of being parallel. PARALLE'PIPED A solid contained by six planes, three of which are parallel to the other three. GLOSSARY. GEOLOGY. 229 PA'RASITE An adherent, a hanger on. PARASI'TIC Of the nature of a para- site. PARI'ETES fr. lat. paries, a wall. The sides or parts forming an en- closure. PARIS BASIN (p. 79). PECO'PTERIS fr. gr. pekos, sheep- skin, pteris, a fern. A genus of fos- sil ferns. PE'CTEK Lat. A comb. A genus of bivalve mollusks. PECTIKA'TA Lat. Pectinate; like the teeth of a comb. PE'LLICLE fr. lat. pellis, a skin. A thin skin, or crust. PEJTINE FORMATION New red sand- stone (p. 47). PENTA'MERUS or PENTAME'RUS fr. gr. pente, five, meros, a part (p. 31). PEJTTA'NGULA'TUS Lat. Having five angles. PERCOLATE fr. lat. per, through, co/o, I strain. To strain or drip through. PE'RIDOT Prismatic chrysolite (p. 121). PE'RLITE Pearlstone, a gray variety of obsidian. PERMANENT GAS Any gas which remains in the aeriform state under ordinary circumstances. PERO'XIDE The highest degree of oxidizement of which a metal or other substance is susceptible with- out becoming an acid. PES-PELICA'NI Lat. Pelican foot. PHANEROGA'MIA fr. gr. phaneros, evident, gamos, marriage. The di- vision of the vegetable kingdom in which all the plants bear flowers, and are multiplied by means of true PHANERO'GAMOUS Belonging or re- lating to phaneroga'mia. PHEjfo'MEjr A Plur. of phenomenon. PHENO'MENON Gr. Appearance, vi- sible quality, event. PHO'LAS fr. gr. p/ioleos, a lurking place. A genus of mollusks. 20 PHO'LADKS Plur. of Pholas. PHO'LODOMY'A A genus of mol- lusks. PHO'NOLITE Clinkstone, a species of compact basalt, which is sonor- ous when struck (p. 171). PHOSPHO'HIC ? fr. gr. phos, light. PHOSPHORE'SCEST 3 Emitting light in the dark. PISTILLIFO'RMIS Lat. In form of a pistil. PLACOIDEANS (p. 48). PLACU'NEA Lat. fr. gr. plakoeis, broad, flat, even. PL.EXERKALK Ger. (p. 71). PLAGIO'STOMA fr. gr. plagios, ob- lique, stoma, mouth. A genus of bivalve mollusks. PLANO'RBIS fr. lat. planus, flat, or- bis, a circle. A genus of marsh snails (p. 83). PLA'NUS Lat. Flat. PLASTIC CLAY (p. 78). PLASTER OF PARIS A substance pre- pared by heating gypsum. PLA'TEAU Fr. An elevated plane, or table land. PLA'TEAUX (PLA'-TO) Plur. of pla- teau. PLATI'N A or PLATI'NITM fr. sp. pla- ta, silver, on account of its colour. A metal of a whitish colour, exceed- ingly ductile, malleable, and of diffi- cult fusion. PLATTSO'MUS (p. 48). PLEI'SIOSAU'RUS (p. 57). PLEIS'TOCENE fr. gr. pleistos, the most, kainos, recent. The newer pliocene formation or newest tertia- ry- PLEU'RONECTES fr. gr. pleura, side, nektes, swimmer. A genus of fishes. PLEURO'TOMA fr. gr. pleura, side, tome, a notch. A genus of univalve mollusks, having a notch in the side of the shell. PLEUROTOMA'RIA A tribe of mol- lusks. PLICA'TULA fr. lat. plica, a fold. A genus of mollusks (p. 72). PLI'OCENE (p. 78 and 89). 230 GLOSSARY. GEOLOGY. PLUTONIC After Pluto, the god of fire. Relating to fire. POIKILI'TIC fr. gr. poikilos, varie- gated. A name applied to the new red sandstone formation in con- sequence of the varieties of colours it exhibits. PO'LYP fr. gr. polus, many, pous, foot. A radiated animal which has a cylindrical or oval body, or sac, with an opening at one extremity, around which are long feelers. POLYPA'HIA, and POLTPIA'RIA Groups of polyps or animalcules which form coral. POLYPA'RIUM The skeleton or frame- work formed by coral animalcules. When this frame-work is of a stony hardness it constitutes coral. In fossils the polyparium alone re- mains. PO'ROUS Containing pores. PORPHTRI'TIC Of the nature of por- POR'PHYROID Resembling porphyry. PORPHYRY fr. gr. porphura, purple. Originally applied to a red rock found in Egypt. A compact feld- spalhic rock containing disseminat- ed crystals of feldspar, the latter when polished, forming small angu- lar spots, of a light colour, thickly sprinkled over the surface. The rock is of various colours, dark green, red, blue, black, &c. PORRE'CTA Lat. Extended. PORTLAND O'OLITE (p. 64). POSIDO'NIA (p. 52). POZZUOLA'NA and POUZZUOLANI Volcanic ashes used in the manu- facture of mortar which hardens under water: exported from Poz- zuoli, near Naples. PRECIPITA'TION The action, by which a body abandons a liquid in which it is dissolved or suspended, and becomes deposited at the bot- tom. PRISMA'TICUM Lat. Prismatic. PRODU'CTUS A genus of extinct mol- lusks (p. 29, 30, and 39). PTERI'CHTHYS (p. 32). PTERODA'CTYLI Lat. Plur. of pte- rodactyl us. PTERODA'CTYLUS (p. 57). PTERO'PH YLLUM fr. gr.pteron, wing, phullon,\eaf. A genus of fossil plants. PUDDING STONE Conglomerate. P.UMICE Vesicular obsidian. PY'RITES A compound of sulphur and iron. PY'ROXENE (p. 121). PYROXENIC Of the nature of py- roxene. QUADERSANDSTEIN Ger. The lower cretaceous beds in Germany : any sandstone fit for building purposes. QUAQ.UAVERSAL Turning each way. QUARRY A stone mine ; a place where stones are dug. QUARTZ Ger. Rock crystal. A con- stituent of granite and some other rocks. QUA'HTZOSE Of the nature of quartz. RADIA'TA Lat Radiate : the name of a class of zo'ophytes. RA'DTATE fr. lat. radius, a ray. Furnished with rays. RA'DIUS Lat. A ray. The semi- diameter of a circle ; a ray drawn from the centre to the circumference. RADIA'TTON The emission of rays of light, or of heat, from a luminous or a heated body. RA'DIOLITES A genus of fossil shells ; the inferior valve of which is in the shape of a reversed cone, the superior valve convex (p. 69). RAFT Trunks of trees and other vegetable debris matted together, by natural causes, and sunk in a river or stream. RAG (p. 59). RAPI'LLI Small volcanic cinders. REACTION The force exerted by two bodies which act mutually on each other. REA'LGAR Red sulphnret of arsenic. A compound of sulphur and ar- senic. REFRIGERA'TION The act of cool- ing. GLOSSARY. GEOLOGY. 231 RESINOUS Containing resin. RETU'SUS Lat. Retuse ; blunted. RKVOLU'TA Lat. Turned again. ROCK Any mineral aggregate (p.13). RODENTIA fr. lat. rodere, to gnaw. An order of mammals. RODENTS Gnawers ; animals of the order of rodentia. ROLLED FLINTS (p. 129). ROSTELLA'RIA fr. lat. rostellum, a little beak. A genus of univalve mollusks (p. 85). ROTHOMAGE'NSIS Lat. from rotho- ma'gum, a temple of Roth, a di- vinity of that part of Gaul, now called Normandy ; hence too the name of the city Rouen. Belong- ing or relating to Rouen. Specific name of an ammonite. ROTHE-TODTE-LIEGENDE Ger. New red sandstone (note, p. 47). ROTA'TA Lat. Rotate; wheel- shaped. ROTU'NDUS Lat. Round. RUBBLE Angular and broken frag- ments of subjacent rock lying be- neath the superficial mould. RUDI'STES fr. lat. rudis, unacquaint- ed, because the characters of the animal were unknown. Name of a family of extinct mollusks in the shells of which neither the hinge, the ligament of the valves, nor the muscle of attachment is discover- able. The family contains six genera : Spherulite.s, Radiolites, Calceola, Birostrites, Distinct, and Crania. RC'GOSA Lat. Rugose, wrinkled. RUGOSITY A wrinkling. RUMINA'NTIA Order of mammals which chew the cud. RUMINANTS Animals that chew the cud. RYA'COLITE (p. 120). SACCHAROID fr. lat. saccharum, sugar, and gr. eidos, resemblance. Resembling loaf-sugar. SAL-AMMONIAC A compound of ammonia and hydrochloric acid. Muriate of ammonia. SALI'FEROUS FORMATION (p. 47). SALT Any combination of an acid with a saliiiable substance. SANDALI'NA Lat. Sandal-like. SANDSTEIN Ger. Sandstone. SANDSTONE Any rock consisting of aggregated grains of sand. SAU'RIANS fr. gr. sauros, a lizard. Animals of the lizard tribe. SAUROID fr. gr. sauros, a lizard, ez- dos, resemblance. Resembling a lizard. SAXI'GENOUS fr. lat. saxum, rock, and gr. geinomai, I produce. Rock producing ; rock forming. SCA'BRA Lat. Rough. SCAPIII'TES fr. gr. skapke, a boat. The boat ammonite (p. 73). SCHIST Ger. fr. gr. schistos, split. Slate. SCHISTO'SE Slaty. SCO'RI^ Lat. plur. of scoria, dross. Volcanic cinders. Cinders and slags of basaltic lavas of a reddish brown and black colour. SCORIA'CEOUS Of the nature of scoria?. SCO'RIFORM In form of scoriae. SEAMS Thin layers or strata inter- posed between others. SECONDARY FORMATION (p. 36). SECRETED Separated by the action of organs. SE'DIMENT fr. lat. sedeo, I sit, that which subsides, or settles to the bottom of any liquid ; dregs. SEDIME'NTART Belonging or relat- ing to sediment. SEL'ENITE A variety of gypsum. SELLA Lat. A saddle. SEMICRT'STALLINE Partly crystal- line. SENSIBLY Perceptibly. SE'PIA A kind of paint or ink pre- pared from the cuttle-fish. SEPTA Lat. plur. of septum. SEPTA'RIA Flattened balls of stone, which have been more or less cracked in different directions and cemented together by mineral mat- ter which fills the fissures." 232 GLOSSARY. GEOLOGY. SEPTUM Lat. A partition. SERIATE' Lat. fr. seria, ajar. Jar- like. SER'PENTINE A magnesian rock of various colours and often speckled like a serpents back. It is gene- rally dark green. SER'PULA fr. lat. serpo, I creep. A genus of anneli'dans which inhabit a calcareous tube, usually adherent to the shells of mollusks. SES'SILE fr. lat. sessilis, dwarfish. Without a pedicle or support. SHALE An indurated slaty clay, or clay-slate. SHIITGLE Loose, water-worn gravel and pebbles. SIGILLA'RIA fr. lat. si'gillum, a seal. Fossil plants found in the coal formation. SI'LEX fr. gr. chalis, a pebble. The principal constituent of quartz, rock- crystal, flint, and other silicious minerals. SI'LICA Silicious earth ; the oxide of silicon (the elementary basis of si- lica), constituting almost the whole of silex or flint. It combines with many of the metallic oxides, and is hence sometimes called sili'cic acid. SI'LICATE A compound of silicic acid and a base ; silicate of iron is a compound of silicic acid and oxide of iron ; plate-glass and win- dow-glass are silicates of soda and potassa, and flint-glass is a similar compound with a large addition of silicate of lead. SILI'CIOUS Containing silica. SILI'CIFIED Petrified or mineralized by silicious earth. SILT The name given to the sand, clay, and earth which accumulate in running waters. SILU'RIAIT STSTEM Series of rocks formerly known as the greywacke series (p. 28). SIITUA'TA Lat. Hollow, excavated. Si'srus Lat. A hollow or excava- tion. SINUO'SITT A hollow, an irregular, winding excavation or hollow. SI'PHOW fr. gr. siphon, a tube. A cylindrical canal, perforating the partitions of multilocular shells. SI'PHUNCLE A small siphon. SLATE A well known rock, which is divisible into thin plates or layers. SOCIA'LIS Lat. Social ; relating to companions. SOLFATA'RA It. A volcanic vent emitting sulphur and sulphurous compounds (p. 115). SOLEM Lat. The sun. SOMMA It. (p. 103). SPATA'NGUS fr. gr. spataggos, a spe- cies of echinus. A genus of sea- urchins, having the mouth situated laterally, and but four rows of pores. SPECIES A kind ; a subdivision of genus. SPECIFIC "WEIGHT, or SPECIFIC GRA- VITY The relative weight of one body with that of another of equal volume. Sp;Eifo'pTERis fr. gr. sphen, a wedge, pteris, a fern. A genus of fossil plants. SPHE'NOPHT'LLITES fr. gr. sphen, wedge, phullon, leaf, lithos, stone. A family of fossil plants. SPHE'RULITES fr. gr. sphaira, a sphere, lithos, a stone. A variety of obsidian or pearlstone which occurs in rounded grains. SPINO'SA 7l jat ' Spinous; covered SPIXO'SUM 5 with spines. SPI'RIFER (p. 30). STALA'CTITES fr. gr. stalasso, I drop. Conical concretions of carbonate of lime attached to the roofs of calca- rious caverns, and formed by the gradual dropping of water holding the carbonate in solution. STALA'GMITES Stalactical forma- tions of carbonate of lime, found on the floors of calcareous caverns. STAU'HOTIDE fr. gr. stauros, a cross, eidos, form. Cross-stone. Pris- GLOSSARY. GEOLOGY. 233 matic garnet. It is very abundant in New England. STELLAS Lat. Stars. STIGMA'RIA fr. gr. stigma, an im- pression. A vegetable fossil (p. 42). STHA'TA Lat. plur. of stratum. STRA'TUM Lat. A layer, a bed. STRATTFICA'TION An arrangement in beds or layers. STRA'TIFIED Arranged in strata. STRIPS Lat. Diminutive channels or creases. STRIATED Marked with strise. STRIKE The direction of strata ; the line of bearing (p. 185). SUB Lat. Under. SUBAPENNINE Applied to a portion of the pliocene strata. Low hills which border the Apennines. SUBLIMA'TION The process by which volatile substances are raised by heat, and again condensed into the solid form. The substances so obtained are called sub'limates. SUBMARINE Beneath the sea. SUBMERGED Immersed or covered by water. SUBPLICA'TA Lat. Somewhat plait- ed. SUBSIDENCE (p. 99). SUBSTRATUM An under-layer or bed. SULCA'TA } Lat. Sulcate ; grooved SULCA'TUS 3 or furrowed. SULPHATISA'TION The act of con- verting into compounds containing sulphur. SUL'PHURET A compound of sul- phur with an other solid. SULPHU'RIC ? Relating to sulphur. SULPHUROUS 3 Applied to acids composed of sulphur and oxygen. SUPERPOSED fr. lat. super, above, pono, I place. Placed above. SYENITE and SIENITE A granitic rock from Syene or Siena, in Egypt. It consists of quartz, feldspar and hornblende. It is tougher than granite and a more durable building stone. SYNCLINAL fr. gr. sun, with, klinein, to incline. Synclinal axis (p. 160). 20* STSTEM OF UPHEAVAL (p. 189 and 191). TABULAR In form of a table; hori- zontal. TALC A foliated magnesian mineral of an unctuous feel, often used for tracing lines on wood, cloth, &c. which are not so easily effaced as those of chalk. TAL'COSE Of the nature of talc. TA'LUS A sloping heap of fragments accumulated at the foot of a steep rock. TEMPERATURE A definite degree of sensible heat. TENDON f. gr. teino, I stretch. A fibrous cord at the extremity of a muscle, by which the muscle is attached to a bone. TEREBE'LLUM fr. lat. terebro, I bore. A genus of gasteropod mollusks. TEREBRA'TULA (p. 30). TER'MINAL Belonging to the end. TERTIARY FORMATION (p. 77). TESTA'CEOUS fr. lat. testa, a shell. Consisting of carbonate of lime and animal matter. TESTUDINA'RIA A tribe of chelonian reptiles. THE'RMAL fr. gr. therme, heat. Warm, hot. THE'RMOMETER fr. gr. therme, heat, metron, measure. An instrument for measuring heat. . THIN OUT Strata are said to thin out when they diminish in thickness. TISSUE fr. lat. tela, a web. A web, or web-like structure, constituting the elementary structures of ani- mals and plants. TRA'CHYTE fr. gr. trachus, rough. A variety of lava. A feldspathic rock, which often contains glassy feldspar and hornblende. When the feldspar crystals are thickly and uniformly disseminated, it is called trachytic porphyry. TRANSITION FORMATION (p. 26). TRAP From the Sweedish trappa, a flight of stairs, because trap rocks frequently occur in large tabular masses rising one above another 234 GLOSSARY. GEOLOGY. like the successive steps of a stair case. Applied to certain igneous rocks composed of feldspar, augite and hornblende. TRA'PPEAN Relating to trap rocks. TRAPEZOIDAL In form of a trape- zium. TRA'VERTIN fr. it. travertino. Lime- stone deposited from water holding carbonate of lime in solution. It is found in the sweet springs of Vir- ginia, and at the hot springs of the Washita, in Arkansas, as well as in many other places. TRE'MOLITE A mineral, often of a fibrous structure, generally contain- ing si'lica, magnesia, and carbonate of lime, originally found in the valley of Tremola on St. Gothard. TRENCHANT Cutting. TRIAS fr. lat. tres, three (p. 49). TRIA'SSIC Of the nature of trias. TRIGONA'LIS Lat. fr. gr. treis, three, gonia, angle. Having three angles or corners. TRIGO'NIA fr. gr. trigonos, three- cornered. A genus of bivalve mol- lusks most of which are extinct. THIGO'NULA Lat. Having three little angles. TRILOBITE (p. 28). TRITURA'TION fr. \&t.tritus, rubbed. The act of rubbing or grinding. TRUNCATE Terminating very ab- ruptly, as if a portion had been cut off. TRUNCA'TUS Lat. Truncate. TU'FA It. A volcanic rock, com- posed of an agglutination of frag mented scorise. TURBO Lat. A twisting. A genus of univalve gasteropods. TURBINA'TA 7 Lat. Shaped like a TURBINA'TUM 5 top. TURRI'CULATED Resembling a tower with turrets. TURRILITES (p. 73). TURRITE'LLA Lat. A little tower or turret. A genus of gasteropods UNCONFORMABLE STRATIFICATION (p. 185). JNDULA'TION A wave ; arranged in a wave-like manner. [JNDULA'TUS Lat. Waved; hav- ing a waved surface. UNILO'CULAR fr. lat. unus, one, lo- culus, partition. Having but one chamber or compartment. U'NIO Lat. A pearl. A genus of mussels. UNIONES plur. of unio. UNSTRATIFIED Not stratified. UPHEAVAL (p. 99). UPTILTED Tilted up ; raised at one end. URSUS Lat A bear. VALLEYS OF DISLOCATION (p. 164). VALLETS OF ELEVATION (p. 161). VA'RIANS Lat. Varying, chang- ing. VAS'CULAR Containing numerous VEGETATIVE LIFE Life of nutrition. VEGETABLE EARTH (p. 14). VEINS (p. 118). VE'NERICA'RDIA fr.Venus, and ca'r- dium. A genus of bivalve mol- lusks. VENTRICO'SA Lat. Ventricose ; in- flated, swelled in the middle. VE'RTEBRA fr. lat. vertere, to turn. A joint or bone of the spine. VE'RTEBRA Plur. of vertebra. VE'RTEBRAL COLUMN The spine or back-bone. VER'TETBATE Having vertebrae, or a spine. VESICULA'RIS Lat. Vesicular ; con- taining vesicles. VI'RGULA Lat. A little rod. VI'RIDIS Lat. Green. VI'TREOCS fr. lat. vitrea, glass. Re- sembling glass. VI'TREO-HES'INOUS Partaking of the nature of glass and resin. VO'LATILE fr. lat. volo, I fly. Capa- ble of assuming the state of vapour, and flying off. VOLA'TILIZE To become volatile. VOLGA 'NIC Relating to a volcano. GLOSSARY. GEOLOGY. 235 VOLT'ZIA A genus of fossil co'nifers. VOIU'TA Lat. A whorl. A genus of gasteropods. VO'SGEAN Belonging or relating to VULGA'RIS Lat. Common. WAL'CHIA A genus of fossil co'nifers (p. 43). WEALD Name of a part of Kent and Surrey in England. WEALDEIT DEPOSIT (p. 69). WHINSTONE A Scotch name for greenstone and other trap rocks. ZA'MIA fr. gr. zemia, loss or damage. A genus of the order Cyca'dese plants. ZECHSTEIIT Ger. A magnesian limestone, lying under the red standstone. ZO'OPHTTE fr. gr. zoon, an animal, phuton, plant. A plant-animal, which seemingly partakes of the pro- perties of both plants and animals. THE END, NEW AND IMPORTANT SCHOOL BOOKS. TO TEACHERS, PRINCIPALS AND CONTROLLERS OF SCHOOLS, ACADEMIES AND COLLEGES We take the liberty of calling your attention to a Series of Books on the subject of Natural History, which, in the opinion of many of the most eminent men in our country, is second to no branch of knowledge now taught in schools. We ask your attention to these books, because we believe them to be superior to any works of the kind ever offered to the American public. They are small in size, extremely cheap, as accurate in scientific arrangement as the most voluminous works on similar subjects, and in every respect, such as parents and teachers would wish to place in the hands of their children. In confirmation of this opinion of the worth of these works, we respectfully invite your attention to the following testimonials. Very respectfully, your obedient servants, GRIGG & ELLIOT, No. 9 North Fourth Street, Philad'a These books have been introduced into the Public Schools of Pennsylvania and Ohio, and no doubt will, ere long, be introduced into all the public schools of our other States. "We regard the introduction of these works into our public schools, among the highest compliments they have received ; for we feel sure that the gentlemen who constitute the committee for selecting books, possess too much discernment and general knowledge, to pass favourably upon works of inferior pretensions. The following gentlemen composed the Committee for selecting books for the use of Public Schools." GEORGE M. W BARTON, Esq. THOMAS H. FORSYTH, Esq. GEORGE EMLEN, Jr., Esq. FRANCIS LYONS, Esq. JOHN C. SMITH, Esq. Philadelphia. In addition to the following flattering notices of the American Press, the pub- iishers have received upwards of one hundred recommendations from the most prominent professors and distinguished teachers of our country, to the superior claims of these works, and urging their introduction as Class Books into all the Schools. Academies, &c., throughout the United States. RTTSCHENBERGER'S SERIES. FIRST BOOKS OF NATURAL HISTORY, SCHOOLS, COLLEGES, AND FAMILIES. 1. ELEMENTS OF ANATOMY AND PHYSIOLOGY. 2. ELEMENTS OF MAMMALOGY, The Natural History of Quadrupeds. 3. ELEMENTS OF ORNITHOLOGY, The Natural History of Birds. 4. ELEMENTS OF HERPETOLOGY AND ICHTHYOLOGY, The Natural History of Reptiles and Fishes. 5. ELEMENTS OF CONCHOLOGY, The Natural History of Shells aud Mollusc a. 6. ELEMENTS OF ENTOMOLOGY, The Natural History of Insects. 7. ELEMENTS OF BOTANY, The Natural History of Plants. 8. ELEMENTS OF GEOLOGY, The Natural History of the Earth's Structure. This interesting series of books has already met with the most flattering reception ever extended to any work issued from the Amer- ican press. Introduced into the Public Schools of Pennsylvania, and in nearly all the first class seminaries of learning in the United States. RECOMMENDATORY NOTICES. " Ruscbenberger's Series of Boohs on Natural History, are among the most valuable and useful works, for the use of Schools that have ever been published. A knowledge of Natural History, is not only valuub'e, but deeply interesting-; and no one's education can, with such faciliiies as these works afford, be considered complete without it." Nntional Intelligencer. "These are the mo-t valuable additions of the day to our stock of School Books. The avidiiy with which they have been seized upon is unprece- dented. Though the first vol. was published for the first time only a few months ago, it has already gone through its fifth edition; the second is fol- lowing close upon its heels; and the third prorni es even to be more popular than either of the other two. These books have been adopted by the * hoyal Council of Public Instruction,' for the use of Schoo's throughout France. They are recommended and have been adopted by some of the most emi nent teachers in the United States." Southern Literary Messenger. From " The Ladies' Companion, a Monthly Magazine." June, 1842, New York. W. Snowden, 109, Fulton Street. "RuscHENBERGEn'a ORNITHOLOGY: Grigg & Elliot. This is an excel, lent book, by one who shows himself perfectly qualified for the task he has undertaken, which is the publishing of a series of works on the different branches of education, for the use of schools and colleges. The present issue is a general and synoptical view of Ornithology, one of the most interesting subjects in Natural History, and will be found of great service, both to teacher and student." " This is a compendious, and, as it seems to us. a judiciously compiled treatise on Ornithology, and one well calculated for the use of Schools ; for which object it is intended." N. Y. Courier and Enquirer. " In the work before us, the plan is happily carried out. In its small compass it embraces an immense amount of useful and interesting infor- mation." Buffalo Adv. and Journal. "Ornithology. This is evidently, like its predecessors, an excellent work of instruction; and ha-s been, in all respects well got up by the publishers." Pennsylvanian, "A valuable little work, and is divided up and classified admirably. The glossary, giving the derivation of the names of birds, is of itself worth the price of the volume." New York Aurora. "An exceedingly interesting, and very instructive book, and one which possesses special Attraction for young ludies." Baltimore Sun. "RusciiENBKRGER's SERIES : Second BooTf. A highly useful and instructive school book. Third Book, This we consider as decidedly an acquisition to our list of school books, the subject is treated of in such a plain style as to be adapted to the simplest capacity. Altogether we think the above series as worthy to take a high and permanent place among our school books " Buffalo Democrat. " We wish we could induce our teachers generally to examine this, as well as the earlier works of Dr. Ruschenberger ; they are admirably arranged, and just the very books needed for schools. The work before us on the Natural History of Birds is an admirable one, and no teachel liould neglect to introduce the series. ' Cincinnati Gazette. "It is an excellent text book of an interesting science, comprising much knowledge in a brief space, presented in a clear style and with lucid arrangement. Dr. Rnschenbergcr, who has already achieved a high charac icr in the literary world, is acquiring additional claims by his exertions i the field of Natural Science. Spectator, Washington City. RECOMMENDATORY NOTICES. u Ruschenberger's Series. These volumes are constructed upon a new and admirable plan, combining great simplicity of arrangement, with a perspicuity and sententiousness of style seldom found in works of this class; and which has elicited the highest encomiums of upwards of thirty of the leading professors of the country, whose opinions have again been endorsed by most of the public prints." U. Slates Adv. "The developement of the principles of classification, is among the very best we have ever seen. Science is here dressed in her own native sim- plicity and beauty, so that the philosopher may admire, while the child may acquire it. Medical Reporter. " It is a choice, and well digested work." Atlas. " An excellent publication adapted to the youthful mind, and a great help to the mure matured." Mercury. "The study of Natural History though generally neglected in schools, is of undoubted use : the present work contains a great amount of infor. mation within a small compass, and properly condenses it for the young mind." N. Y. Journal of Commerce. " Ruschenberger's Series. The subjects are Well treated, and from the exceediiig cheapness, and admirable arrangt meu; of these elementary works, they are well fitted for general use in public schools and academies." New York American. " We do not hesitate to say, that this is the best work of the kind and dimensions, that has even fallen under our notice. We hope all will embrace the first opportunity of procuring a copy, as we are sure they will prize it highly." Botanic Recorder. " A well digested and curefu'ly arranged abstract of the most interesting parts of Natural Science." Philadelphia Gazette " Admirably adapted to convey an elementary knowledge on the subject of which it treats; and will be found an excellent book for the student." Public Ledger. " Valuable in every respect, it contains a vast amount of information, condensed into an available form, for the use of schools." Spirit of the Times, "Just such a work as is wanted for elementary instruction, in this pleas- ing branch of science." New York Evening Post. " We regard this series as eminently useful, supplying adequately the instruction in natural history necessary to a proper school education." North American. " It is an excellent little work for the purpose designed, written in a cl ar and familiar style, and will not fail to facilitate the studies of those who wish to make themselves acquainted with the subject." Saturday Courier. "Admirably adapted for elementary instruction." Saturday Chronicle. " We have great pleasure in recommending it as an excellent elementary manual on the subject " Medical Examiner. "Ornithology This book is equal in merit to the first and second, and is a most valuable work. It is intended for the use of schools and acade- mies, and we would call the attention of parents and others to the series of books to which this belongs, assuring them at the same time, that it will answer the purpose for which it is intended, better than any other work of the kind that we ever saw, or, in our opinion, that was ever published in this country. It is divided into questions and answers, contains an exten- sive and valuable Glossary, and is illustrated by eight Plates ; and what is more the price is so very low that every person can aflord to purchase it. Yoik New Era. .T~: 4 NEW SERIES OF ENGLISH SCHOOL BOOKS. PUBLISHED AND FOR SALE BT GRIGG & ELLIOT, NO. 9 NORTH FOURTH STREET, PHILADELPHIA. And for Sale by Booksellers and Country Merchants generally in the U. S. To Teachers, Principals and Controllers of Schools, Academies and Colleges throughout the United States. Philadelphia, 9 North Fourth Street. SIR: Believing that you take an interest in educational im- provements, we beg leave to call your attention to an admirable series of School Books on Natural History, prepared by Dr. Rus- chenberger. There have hitherto been few works, if any, on this subject, suited to the capacity of pupils at an early age. The series referred to has, therefore, met with a most cordial reception throughout the country, from teachers, naturalists, and men of letters. The volumes are eight in number the first being de- voted to Anatomy and Physiology ; the second to Mammalogy ; the third to Ornithology ; the fourth to Herpetology and Ichthy- ology ; the fifth to Conchology ; the sixth to Entomology ; the seventh to Botany ; and the eighth to Geology. They are small in size, extremely cheap, as accurate in scientific arrangement as the most voluminous works on similar subjects, and in every respect such as intelligent parents would wish to place in the hands of their children. Each work is entirely independent of the others. The retail price is only fifty cents per volume for the first seven volumes. Orders sent to us directly, or through any bookseller, or country merchant, will be promptly attended to. Respectfully, your obedient servants, GRIGG & ELLIQT. 1 CRICC & ELLIOT, Publish the following valuable list of SCHOOL BOOKS, which consti- tute a regular series of ELEMENTARY WORKS, designed for the use of COLLEGES, ACADEMIES, and SCHOOLS, also for family use. The publishers hope that all TEACHERS who have their pupils' in- terest at heart, will examine these valuable series of School Books before introducing any others; and they particularly request that all TEACHERS and DIRECTORS of our PUBLIC SCHOOLS in the various states will examine G. & E.'s new SERIES of COMMON SCHOOL READERS, and their other School Books before introducing any others. TO TEACHERS AND SCHOOL COMMITTEES, RUSCHENBERGER'S popular series of SCHOOL BOOKS on Natural History, prepared for the use of Schools, by Dr. W. S. W. Ruschenberger, from the text of Milne, Edwards, &c. 1, Elements of Anatomy and Physiology, - - 45 cuts. 2, Elements of Mammalogy, - - - - 75 " 3, Elements of Ornithology, - - - - 81 " 4, Elements of Herpetology and Ichthyology, - 66 " 5, Elements of Conchology, - - - v ( - 119 ' 6, Elements of Entomology, - - - - - 91 " 7, Elements of Botany, - - - - - - 194 " 8, Elements of Geology, about - - - - - 300 " Each book of the series is complete in itself, and has a full glossary ap- pended. The illustrations are numerous, and beautifully executed. Teach- ers are respectfully invited to call and examine these works before selecting for their schools any books on Natural History, these being very cheap, and having been approved by distinguished and scientific men. Among the very numerous notices received from all parts of the United States, the publishers subjoin the following: " We have no handbooks equal to these, and we think Dr. R. has con- ferred an obligation upon teachers and learners, by producing them in an English dress, with all the advantages of well engraved illustrations. The whole set of this work, which is furnished at a low price, will prove an in- valuable acquisition to the school library." " Dr. Ruschenberger' s series of books on Natural History. We have hastily glanced over the first four numbers, and have profited much by their peru- sal. Besides being a complete system, the different subjects are treated in a concise and elegant style by the author. The work is peculiarly adapted to the use of our District Schools, and when we see this important branch of general education so much neglected, we would urge upon our directors to examine Dr. Ruschenberger's Series, and place it where in justice it should be, in every district school in the country." "These 4 First Books 1 of D*r. R. have been everywhere received with great and deserved commendation, and they will be found well to merit the attention of teachers throughout the United States, as furnishing a means GRIGG & ELLIOT'S SCHOOL BOOKS. 3 of instruction not otherwise to be met with, upon subjects of the utmost importance to a course of liberal education. " We have, from the same publishers, a set of their series of ' Common School Readers' 1 four in all, arranged progressively of which, we under- stand, that no less than 70,000 have been sold in a short period, a fact affording conclusive evidence of the estimation in which these reading books are held. These volumes are so arranged as to bring the learner forward from matters of simple information to subjects of high interest in morals and history, and are well calculated, not only to instruct at the time, but likewise to create a fondness for the acquisition of knowledge." "Our Booksellers have just received complete sets of Dr. Ruschenber- ger's elementary works on Natural History, for ihe use of schools and col- leges, and to which we would call the attention of those having the instruc- tion of our youth in charge. The style of the author appears to be clear and succinct, and the various subjects are illustrated by appropriate draw- ings. We learn that Dr. R.'s works have been introduced into the public schools of Pennsylvania, Ohio, .Mississippi, and other States, and in nearly all the first class seminaries of learning in the United States, and have always met with a reception truly flattering. "In addition, they have for sale Grigg~& Elliot's new series of Com- mon School Readers. We have not time to examine them thoroughly, but to judge from the many encomiums they have received from the high- est sources, we should think they were destined to occupy a high place in the esteem of those interested in the cause of education." New Orleans Picayune, Jan. 4, 1845. New and Valuable School Books. " In view of the long list of recommen- dary notices by many of the most distinguished teachers in the Union, and by a cursory examination ourselves, we can cheerfully declare thai no TEACHER or SCHOOL should be without this series of school books. We invite all those interested to call at Davis' and examine them, where they are for sale, wholesale and retail at very low prices." Indiana State Journal, Indianapolis. "Messrs. Grigg & Elliot, Philadelphia, have published an interesting series of books, which we commend to the attention of TEACHERS. A series of Readers, adapted to successive classes, which seem. to us well se- lected and arranged. A far more important series, and one long called for, in the shape of elementary scientific treatises on the following subjects: Mammalogy, Ornithology, Herpetology and Ichthyology, Botany, Concholo- gy, Anatomy and Physiology, and Geology. These works are prepared by Dr. Ruschenberger, on the plan and materials of similar books used in Ihe public schools of France. They are illustrated with the necessary plates, and are complete in their treatment of the subject, and undoubtedly deserve a place in our now meagre list of elementary class books of science. These works are for sale by M'Carter& Allen, Charleston, S.C., Allen, M'Carter & Co., Columbia, and Thomas Richards, Augusta, Ga." Charleston Mercury. The publishers have just received, for one school, in Bangor, Maine, an order for seventy-five copies each of the above valuable works, which is an evidence of the high estimation in which they are held in that section of country, by some among the best teachers in New England. 4 GRIGG & ELLIOT'S SCHOOL BOOKS. Portland, August 22, 1845. DEAR SIR : Your note, accompanying Dr. Ruschenberger's Elementary Books on Natural History, for the use of schools, &c., was duly received, for which please accept, for yourself and the publishers, my sincere thanks. Having examined several of the volumes, I take great pleasure in ex- pressing my approbation of the work. It is better adapted to the purposes of elementary instruction than any other cheap work with which I am ac- quainted. Among its many merits I regard that of the constant adherence of the author to the language of science as peculiarly worthy of notice. Although the descriptions of the various objects treated of may appear obscure at first sight, every difficulty is removed by the copious glossary which ac- companies each volume. While the student is acquiring accurate instruc- tion in natural history, he is, at the same time, and with no additional labour, adding essentially to his vocabulary. With these remarks I would most cordially recommend the work as well adapted to fulfil the objects for which it is published. With much respect yours truly, J. W. M1GHELS, Member of the Natural History Societies in Boston and Portland, also of the American Association of Geologists,