_n_n_n_ji_n-. _n-jv_ji_n_n_n_n_n__n_n_n-_n_n_n_n_ii_rv REESE LIBRARY 1 UNIVERSITY OF CALIFORNIA. APR 10 1894 , 189 . ^Accessions No. &. CLiss No. UHIVERSIT1 TEXT BOOK OF COMPARATIVE GEOLOGY TEXT BOOK OF COMPARATIVE GEOLOGY BY E. KAYSER, PH.D. Professor of Geology in the University of Marburg TRANSLATED AND EDITED BY PHILIP LAKE, M.A., F.G.S. Late Harkness Scholar in the University of Cambridge WITH 596 ILLUSTRATIONS (73 PLATES AND 70 FIGURES IN THE TEXT) iLontion SWAN SONNENSCHEIN & CO. NEW YORK: MACMILLAN & CO. 1893 BCTLEK & TANNER, THE SELWOOD PRINTING WOKKS FKOMK, AND LONDON. PREFACE. A JUST conception of the science of geology is scarcely to be gained by the examination of any single country : the outlook must be broad and must, as far as possible, include the whole earth. It is to the use of the comparative method that we owe the striking generalisations of Neumayr and the philosophical views of Suess. Even in the study of a particular district, comparison with other areas is invaluable ; for the key to the geology will oft%n be found in some far distant region. South Devonshire, for example, was very imperfectly understood until Mr. Ussher applied the know- ledge which had been won in the Rhenish Mountains. There is, however, no text book in the English language which affords sufficient help in such comparisons, for there is none which gives an adequate account even of the geology of Europe ; and it is with the object of supplying this deficiency, in part at least, that the translation of Dr. Kayser's " Lehrbuch der geologischen Formationskunde " has been undertaken. Dr. Kayser's work was intended primarily for use in Germany ; but the space devoted to other countries is much larger than in earlier text books. In the present edition very considerable additions have been made to the portions descriptive of extra-German countries. These additions are most numerous in the first half of the work, while in the latter half the greatness of the subject and the limits of space have made themselves more severely felt. Extra-European rocks have necessarily received but brief notice. fr VI PREFACE. Besides these additions the chief alteration that has been made is that the Cambro-Silurian rocks have been divided into Cam- brian, Ordovician and Silurian instead of into Cambrian and Silurian. The illustrations with few exceptions are the same as in the German edition ; and they will be found of the greatest value in imparting to the student a knowledge of characteristic and zone fossils. In the preparation of the book my thanks are due to Prof. Of. A. Lebour and Mr. J. E. Marr, F.R.S., for valuable advice and notes * in certain portions of the work ; and above all to Dr. Kayser him- self, who has read through the whole of the proof sheets and has added some supplementary remarks. PHILIP LAKE. CONTENTS. PAGE INTRODUCTION 1 I. ARCHAEAN OR PRIMITIVE ROCKS 13 GENERAL CHARACTER AND COMPOSITION OF . . .13 STRUCTURE AND MODE OF OCCURRENCE OF .... 17 CLASSIFICATION OF .19 DISTRIBUTION OF 23 VIEWS ON THE ORIGIN OF 24 II. PALAEOZOIC OR PRIMARY GROUP 27 CAMBRO-SILURIAN ROCKS 28 Historical 28 General Eemarks 30 A. CAMBRIAN SYSTEM 32 Palaeontology of 45 B. ORDOVICIAN SYSTEM 50 C. SILURIAN SYSTEM 64 Palaeontology of Ordovician and Silurian Systems 73 D. DEVONIAN SYSTEM 89 Historical 39 Distribution and Development of . .91 Palaeontology of 113 E. CARBONIFEROUS SYSTEM 12*5 General and Historical 125 Distribution and Development of Central and Western Europe .... 129 The Mediterranean Eegion .... 142 Eussia 144 Extra-European Areas 146 On the Mode of Formation of Coal .... 148 Palaeontology of 150 F. PERMIAN SYSTEM 164 General and Historical 164 Distribution and Composition of German Facies 167 Eussian Facies 178 The Permo-Carboniferous Glacial Epoch . . .183 Palaeontology of ./ 185 III. MESOZOIC OR SECONDARY GROUP 193 A. TRIASSIC SYSTEM 194 General and Historical 194 The German Facies of the Trias. . . .196 The Alpine Trias. . . . . . .217 Palaeontology of 230 Vlll CONTENTS. PAGE B. JURASSIC SYSTEM 235 General and Historical 235 Distribution and Development of Jura of Central Europe 239 The Alpine Jura 262 The Kussian Jura 269 Climatic Zones of 270 Palaeontology of . 271 C. CRETACEOUS SYSTEM 279 General and Historical . . . . . . 279 Distribution and Development of Lower Cretaceous 284 Germany, N. France, and England . . 284 S.Europe 296 Upper Cretaceous 299 Germany, England, and N. France . . 299 S. Europe 315 Extra-European Cretaceous .... 318 Palaeontology of 319 IV. NEOZOIC GROUP 326 A. TERTIARY SYSTEM 327 General and Historical 327 Older Tertiary or Palaeogene 332 1. Eocene 332 2. Oligocene 339 Palaeontology of Older Tertiary . . . .348 Newer Tertiary or Neogene 353 1. Miocene 353 2. Pliocene . 362 Palaeontology of Newer Tertiary .... 366 B. QUATERNARY SYSTEM 373 1. Drift or Diluvium 374 General and Historical 374 Distribution and Development of . . . 378 Mammalia of 393 2. Alluvium . 399 LIST OF PLATES. PLATE PAGE I. Cambrian Trilobites ... ..... 46 II, Fossils ......... 47 III. Ordovician Trilobites ........ 76 IV. Mollusca ........ 77 V. Brachiopods and Cystideans .... 78 VI. and Silurian Coelenterates .... 79 VII. Silurian Crustacea ...... , . .80 VIII. and Cephalopoda ..... 81 IX. Molluscs . . ....... 82 X. Brachiopods and Corals ...... 83 XI. Ccelenterates ........ 84 XII. Lower Devonian Fossils ....... 114 XIII. ....... 115 XIV. Middle Mollusca ....... 116 XV. ., Fossils ....... 117 XVI. Corals and Crinoids ..... 118 XVII. Upper Fossils . ...... 119 XVIII. Fossils from the Upper Devonian, etc ...... 120 XIX. Hercynian Fossils ......... 121 XX. Fossils of the Culm and Carboniferous Limestone . . 151 XXI. Cephalopods and Gasteropods of the Carboniferous Lime- stone .......... 152 XXII. Brachiopods and Lamellibranchs of the Carboniferous Limestone ......... 153 XXIII. Carboniferous Limestone Coelenterates .... 154 XXIV. Coal Measure Plants ........ 155 XXV. ........ 156 XXVI. ,, ........ 157 XXVII. Plant and Animal remains of the Coal Measures . . 158 XXVIII. Fossils of the Marine Upper Carboniferous . . .159 XXIX. Eothliegende ....... 187 XXX. ....... 188 XXXI. Fossils of the Zechstein ........ 189 XXXII. Permian Fossils ......... 190 XXXIII. Fossils of the Bunter Sandstone ...... 201 XXXIV. Muschelkalk Fossils . . . . . . . . .204 XXXV. ..... > ... 205 XXXVI. Keuper Fossils ......... 211 XXXVII. Fossils of the Keuper and of the Karoo Series . . .212 XXXVIII. Bunter Sandstone and the Muschelkajk of the Alps ..... ..... 221 ix LIST OF PLATES. PLATE PAGE XXXIX. Fossils of the Norian Series of the Alps .... 222 XL. Carinthian and Rhsetic Series of the Alps . 223 XLI. Lower Lias 245 XLII. ,, ,, Middle Lias 246 XLIII. n n Upper Lias 247 XLIV. ., Lower Oolite ....... 254 XLV. 255 XLVI. ,, Great Oolite and of the Keliaways Rock 256 XL VII. ,, ,, Oxfordian and Corallian .... 263 XLVIII. Kimeridgian 264 XLIX. and Portlandian, also Titho- nian 265 L. Fossils of the Wealden 285 LI. ,, ,, Neocomian 290 LIL ,, Albian and Aptian 294 LIII. Alpine Lower Cretaceous .... 297 LIV. ,, ,, Cenomanian 301 LV. ,, ,, and Turonian .... 302 LVI. Turonian 303 LVII. Senonian 305 LVIII. ,, ,, ........ 306 LIX. 307 LX. 308 LXI. ,, Alpine Upper Cretaceous .... 317 LXII. Eocene Mollusca 333 LXIII. 334 LXIV. Fossils of the Nummulitic Beds 338 LXV. Oligocene Mollusca 343 LXVI. Fossils 344 LXVII. Miocene Gasteropoda 357 LXVIII. Mollusca 358 LXIX. Fossils 359 LXX. Pliocene Mollusca 364 LXXI. Mammals of the Drift 394 LXXII. 395 LXX III. and Molluscs of the Drift 396 LIST OF FIGURES. 1. Section near Wolmersdorf in Lower Austria (v. Hauer) . . 16 2. through the Pfahl in Eastern Bavaria (Gtimbel) . . 16 3. in the King Mine in New Jersey (Wtirtz) .... 17 4. through the Archsean at Grenville in Canada (Logan) . 18 5. a part of the Bavarian Hills (Gtimbel) . . 18 6. St. Gotthard and the Finsteraarhorn (A. Heim). 20 7. Mont Pelvoux (Lory) 20 8. Mont Blanc (A. Favre and Lory) .... 21 9. the Simplon (Lory) 21 10. ,, in the Menomonee area in Michigan (Credner) ... 23 11. of Kinekulle on Lake Wener . . . . . .35 12. Diagrammatic section through the Lower Palaeozoic Rocks of Bohemia (Fr. Katzer) 58 13. Section from Finland through the islands of Oesel, Gotland, and Oeland to Sweden (Fr. Schmidt) ....... 70 14. Section through a part of the Schiefergebirge of the Eifel (Baur) 92 15. Meganteris Archiaci, Vern, from the Lower Devonian of the Eifel (with the dorsal shell broken open to show the long internal loop) 122 16. Section on the West Coast of Arran (F. Zirkel) . . . . 129 17. through the Coal Basin of Liege (Vancherpenzeel-Thim). 135 18. of the Carboniferous and Devonian near Aix-la-Chapelle (F. Holzapfel) 136 19. Section through the Coal Basin of Ruhr (H. Br. Geinitz) . . 137 20. ,, ,, ,, Carboniferous and Rothliegende of the Saar and Nahe Area (Nasse) 137 21. Section through the Alleghany Mountains 147 22. Upright Trunks in the Carboniferous of St. Etienne . . .150 23. Section through the Rothliegende and accompanying eruptive rocks 011 the left bank of the Nahe above Miinster (H. Laspeyres) 169 24. Section through the Erzgebirge Basin at Chemnitz (Siegert) . 171 25. Salt beds of Stassfurt (Bischof) . . .176 26. Glossopteris Browniana, Brngn. 184 27. Callipteris conferta, Brngn. 185 28. Section through the Mesozoic Rocks of Hanover (Heinr. Credner) 193 29. False-bedding in the Middle Bunter Sandstone near Marburg . 199 30. Section of the Trias in the neighbourhood of Mutzig and Sulzbad, on the Eastern border of the Vosges (Benecke) . . . .208 31. Section of the Trias in the neighbourhood of Oberheldrtingeii in Thuringia 208 32. The Dolomite Reefs of the Sett Sass in the Southern Tyrol . . 226 33. Section through the Trias of Lunz in the Lower Austrian Alps (Bittiier) '. 227 xii LIST OF FIGURES. FIG. PAGK 34. Section through the Triassic and Jurassic Beds of Swabia . . 240 35. ,, ,, Upper Jurassic of the Porta Westfalica (Heinr. Credner) 240 36. Lepidotus notopterus, Agass 274 37. Leptolepis sprattiformis, Agass 274 38. Ichthyosaurus communis, Conyb. 276 39. Plesiosaurus dolichodeirus, Conyb * . 276 40. Pterodactylus spectabilis, H. v. Mey 277 41. Restoration of Ramphorliynclms phyllurus, Marsh .... 277 42. Archceopteryx macrura, Owen 278 43. Hesperornis regalis, Marsh ........ 323 43A. Tooth of Hesperornis regalis, with germ of succeeding tooth . 323 44. Ichthyornis victor, Marsh 324 45. Section of the Tertiary Beds of Brandenburg (G. Berendt) . . 342 46. Oligocene Lignite deposits of the neighbourhood of Halle on the Saal (H. Laspeyres) 345 47. Chamaerops helvetica, Heer. Lower Oligocene of Nachterstadt, . near Halle on the Saal 349 48. Lamna cuspidata, Ag., Oligocene 350 49. Otodus obliquus, Ag., Eocene 350 50. Pal(Kotherium magnum, Cuvier. Oligocene, Montmartre, near Paris 351 51. Skull of Loxolophodon (Dinoceras) mirabilis, Marsh. Eocene of Wyoming 352 52. Section through the Meissner, near Cassel (Fr. Moesta) . . 356 58. Diagrammatic Section through the Vienna Tertiary Basin (Karrer) 361 54. Dinotherium giganteum, Kaup. Pliocene of Eppelsheim. . . 366 55. Upper molar teeth of Dinotherium giganteum, Kaup. . . . 366 56. Mastodon angustidens, Cuv. Miocene of Simorre, France . . 367 57. Last molar of the upper jaw of Mastodon angustidens, Cuv., seen from above 367 58. Last molar of the lower jaw of Mastodon turicensis, Schinz., seen from the side 367 59. Hippotherium gracile, Kaup. Pliocene of Pikermi . . . 368 60. Upper molars and hind feet of (a) Palceotherium ; (b) Anchithe- rium ; (c) Hippotherium ; (d) Equus 368 61. Tooth of Anchitherium (A) ; Hippotherium (B) and Equus (C) . 370 62. Upper molar of Aceratherium incisivum 370 63. Rhinoceros (Aceratherium'] incisivus, Cuv 370 64. Rhinoceros (Dihoplus) Schleiermacheri, Kaup 370 65. Antlers of : a. Cervus (Palceomeryx) elegans, Lartet = fur cat us, Hens. ; Miocene, Sansan. b. C. (Pal.) anocerus, Kaup. ; Plio- eene, Eppelsheim. c. C. Matheronis, Gaudr. ; Pliocene, M. Lu- beron. d. C. martialis, Croiz. and Job. ; Pliocene, St. Martial. 371 66. Cervus Sedgwicki. Falc. Upper Miocene, Val d'Arno . . . 372 67. Machcerodus meganthereon, Croiz. and Job. Pliocene of S. France . 372 68. Mylodon robustus, Owen. Argentine Pampas formation . . 373 69. Extent of the ice-sheet and glaciers during the Ice Age in Europe 381 70. Map of the ice-sheet and glaciers in North America . . . 391 INTRODUCTION. GENERAL REMARKS. STRATIGRAPHY or Stratigraphical Geology is but a part of the great science of Geology, i.e. the science of the material (especially the mineralogical) constitution of the globe, its structure and the history of its formation. In Geology, as in other sciences, we can distinguish various branches; such as Physical Geology, which is concerned with the form and size of the earth, its density and temperature, the general contour and relief of its surface and other similar matters ; Dynamical or Mechanical Geology, which treats of the- action of volcanoes, water, etc. ; Tectonic Geology, which describes the arrangement of the rocks composing the crust of the earth; Petrographical Geology or Petrography, which teaches the chemical and mineralogical composition, and the mode of occurrence and distribution, of the various types of rocks; and lastly, Stratigraphical Geology. This undertakes the task of examining the composition, distribution, and organic inclusions- of the geological formations, i.e. of the rock- structures which have arisen at different and successive periods of the earth's history. It thus gives us a kind of history of the development of the globe and of its inhabitants, both animals and plants, from the earliest times to the present. Hence the term Historical Geology is also- tised for this branch of the science ; and when we compare the stratigraphy of various areas, we may well speak of COMPARATIVE: GEOLOGY. If we take a general view of the rocks forming the solid crust of the earth we find that they fall into two chief classes, viz. (1) Eruptive Hocks, which like the lavas of to-day, rose hot and liquid from the inner parts of the earth, and on cooling became firm and solid ; and (2) Sedimentary Rocks, which are either C. G. * B INTRODUCTION. deposits of the solid matter mechanically carried by water, or deposits from mineral solutions. Besides these two great groups, there is a third, which is of but slight importance, viz. the ^Eoliaii or Subaerial Rocks deposits of material borne by the wind and laid down on dry land, as for example, certain mountain loams, volcanic tuffs, and sand dunes. The sedimentary are distinguished from the eruptive rocks chiefly by two peculiarities, their bedding and their fossil con- tents. Bedding or stratification is indeed not universal, but it is found in most sedimentary or " stratified rocks." A stratified de- posit is one in which the whole mass is divided into parallel platy or tabular layers (beds or strata). Each bed is separated from those above and below it by a divisional plane and is to be considered as the result of an uninterrupted process of sedimenta- tion, whilst each divisional plane signifies a pause, however small, in the deposition. If a number of successive beds are of similar constitution and structure, they form a " series," "group," "com- plex," or " system " of beds. As for the fossils, they also are not universal, but are nevertheless found in the greater number of sedimentary rocks. They are the remains imbedded in the rock, and more or less mineralized, 1 of the animals and plants which "lived at the time of the formation of the beds. Our whole system of reckoning time geologically rests ex- clusively on the sedimentary rocks, because it is they alone that afford the means, in their stratification and fossil contents, of tracing their chronological equivalence over wide areas or over the whole earth. The eruptive rocks are of no value for this purpose, because they possess no marks which allow of any certain con- clusions as to their age ; and this can only be determined from that of the sedimentary rocks through which they have broken. With respect to the bedding it has already been noticed that each single bed is to be considered as the representative of a par- ticular, though it may be a relatively very short, period of time. Since each series of beds is composed of numerous beds lying on one another like the leaves of a book, and each system of a number of successive series, it is possible to determine the age of each bed relatively to any other of the same series, and also the age of each 1 A striking exception to this rule is formed by the corpses of mammoths and rhinoceros which are found in the frozen soil of Siberia with their hair and skin preserved. They are not mineralized, but must nevertheless be considered as " fossils." INTRODUCTION. 3 series relatively to any other. Hence we get this most important rule : That in normal circumstances, i.e. when the beds are un- disturbed or but little disturbed, a higher bed is younger than a ilower. According to this principle of stratification, even before there was a science of geology, men separated the older from the younger, or as the old miners expressed it, the " heading " (Liegende) from the " hanging " (Hangende). Concerning the mutual relations of two series it is necessary, in. the first place, to distinguish between conformable and un- conformable sequence. In the first or normal case, both series possess a similar " lie," the strike and dip being the same. We may then conclude that there was no great interval of time between the deposition of the older and the newer beds. In an uiiconform- .able sequence, on the other hand, each of the series has its own peculiar lie differing from that of the other. In this case a cer- tain time must have elapsed between the formation of the older -and that of the newer beds, during which the older beds were moved from their original horizontal position and sometimes set on edge and folded. A peculiar kind of lie, which is too important to be left un- noticed, is known as overlap or transgression. In this case a series lies quite conformably upon the preceding beds, but overlaps the area occupied by these in such a manner as to lie in part immediately on a third, still older series, usually unconformably. Thus, for example, the Rothliegende of the Saar area overlaps the underlying 'Conformable Saarbriick Coal Measures in such a manner that s to the north of the latter it rests directly on the older steeply in- clined Devonian beds of the Hunsrtick. Overlaps indicate that after the deposition of a system of rocks t(in the above example, the Coal Measures) had been accomplished, an overflow of the sea beyond the borders of the basin of deposi- tion took place, in consequence of which the newer series (in our case the Rothliegende) was laid down over a greater area than the older. The possibility of the determination of the age of a rock from its fossils rests on this, that the earth in the course of its history has been peopled by a long succession of very various faunas and floras, and that accordingly the fossils of the several systems and parts of systems are very different from one another. Moreover the labours of several generations of observers have now established ithe evolution of organic life in its principal features ; and at the 4 INTRODUCTION. same time it has become possible, from the character of a given fossil fauna or flora, to determine its relative age, i.e. to determine whether it is older or younger than another. For since the fauna and flora of each geological epoch has been evolved from that of the preceding epoch, and the present life of the world represents only the latest stage of this development, it follows universal^ that, on the one hand, the younger a fossil fauna or flora is, the more like it must be to the present ; and on the other hand, the older it is, the more unlike. This position is indeed only valid in its main features. It cannot be doubted that in former geological ages, just as at the present day, the character of the animal and plant world was influenced by geographical differences. With these there were also other local differences. The terrestrial animals were always unlike the aquatic, and among the latter the dwellers in salt water were different from those in fresh water. Lastly, the in- fluence of height, humidity, soil, etc., must have been as great in all times as it is to-day. All these circumstances must have combined, from the oldest times, to bring about regional differences in the animals and plants inhabiting our earth during any single epoch. Nevertheless it is proved afresh every day, and is confirmed by continual experience, that, leaving out of consideration all local differences, the succession of faunas and floras of the several geo- logical periods has been the same throughout the whole earth. Not only is the sequence of the great Palaeozoic faunas the same from Cambrian to Permian, in the most distant parts of the earth ; but even the various Ammonite faunas of the Jurassic, which .correspond with relatively short periods of time, are re- peated with the most wonderful agreement in the most widety separated parts of Europe and also in India and South America. The determination of the age of beds by means of their fossils is practicable, not only when we deal with strata of one and the same region, but even when these are widely separated from each other, as, for example, when we compare European with American rocks. In that case we .may consider that (1) Strata of the same age (equivalent, homotaxial) contain more or less similar faunas and floras. (2) The resemblance of any fauna or flora to that of the present day is less as its antiquity is greater. The varieties in character of the faunas of beds of the same age r due to local variations in the conditions of life, are known as INTRODUCTION. vpalseontological facies. Thus it is not uncommon to find an Ammonite or Cephalopod facies in a certain area, and near to this <; another facies of the same age of Brachiopods, Lamellibranchs, . Corals, or other forms. Still more marked are the differences J between a marine and an equivalent freshwater facies. The differences in character of the rocks of the various systems \ * and other subdivisions afford but very slender evidence for the 4 -determination of the age of the beds. There was indeed a time ~ when it was thought that each great geological period was char- . acterized by the formation of a perfectly definite type of rock. j It was 'at this time that the expressions, Chalk Formation, Oolite, ^ Grauwacke, Coal Formation, and many others originated. But this idea has been proved to be erroneous. We know now that, for example, Oolitic rocks and Coal occur in the most different ^ j systems ; and on the other hand that the same period may be i represented in different regions by entirely different rocks : in 5 i one area by sandstones and conglomerates, in another by slates, ^ in a third by limestone, etc. T+^ It could not indeed be otherwise ; for the deposition of sediment I group. J rCoal group. ~\ Uebergangsgebirge. Coal period. - Grauwacke ^Palaeozoic group. I group. J TJrgebirge. Archaean. The subdivision of Werner's Transition Rocks (Uebergangs- gebirge), that thick complex of beds which is now known as the Palaeozoic Group, was not attempted till about 1830-1840, when the knowledge of the younger deposits was already far advanced. This was due to the great difficulties which beset the study of the older deposits, and especially to their complicated structure and their poorness in fossils. Germany, where Cambrian and Silurian rocks are almost entirely absent, was an especially difficult area 1 De la Beche distinguished a " Lowest Fossiliferous group " below the Grauwacke. 2 Lethaea yeoynostica, 1833-38, and Handlmch der Geschichte der Xatur, 1841-49. INTRODUCTION. 9 for such an attempt ; and France for this purpose was not much better. England, on the other hand, was far more favourably placed and thus it is in this country that the classification of the older deposits originated, and the Palaeozoic systems are univers- ally known by their English names. The present classification of these rocks, and the relations of the names now in use to the older terms, is shown in the following table : Older terms. Present terms. Lower part of the Ked Sandstone Group. Permian System. Coal group of the English ^ ~ , ., , ._ *? > Carboniferous System. Coal group of Bronn in part. J r Devonian System. Transition or Grauwacke group. I Silurian System. I Ordovician System. [Cambrian System. These six oldest systems of the stratified rocks are united to form the great Palaeozoic Group ; and in the same way the Trias, Jur- assic, and Cretaceous form the Mesozoic; and the Tertiary and Quaternary Systems, the Neozoic l or Kainozoic Group ; while another great group is often distinguished as the Azoic or Archaean, to include the Primitive Rocks of Werner. Each of these great Groups represents a great Era of the Earth's History, while the Systems represent smaller divisions of time, or Periods. The whole of the Sedimentary deposits are thus divided into the following Groups and Systems, and the latter are again subdivided into a number of Series : I. NEOZOIC GROUP. 1. Quaternary System. (Alluvium. \Drift. /Pliocene. 2. Tertiary System. J Miocen e- I Oligocene. { Eocene. II. MESOZOIC GROUP. 1. Cretaceous System. |^P er Cretaceous. I Lower Cretaceous. ( Upper Jurassic. 2. Jurassic System. J Middle Jurassic. vLower Jurassic (Lias). {Keuper. Muschelkalk. Banter. 1 The term Neozoic is sometimes used to include both Mesozoic and Kainozoic, 10 INTRODUCTION. III. PALEOZOIC GROUP. I.Permian System. fZechstein. (Rothliegende. f Upper Carboniferous (Coal Measures). 2. Carboniferous System, -j Lower Carboniferous (Culm and Carboni- : ferous Limestone). Upper Devonian. 3. Devonian System. -[ Middle Devonian. - Lower Devonian. 4. Silurian System. 5. Ordovician System, 6. Cambrian System. IV. AZOIC OR ARCHAEAN GROUP. Primitive Rocks. THE ORIGIN AND EARLY CONDITION OF THE EARTH. The Earth had the same origin as the planets of the solar system, and as the sun itself. Originally all these bodies formed a single mighty globe of gas. From this the planets separated out one after another (and from these their satellites separated in the same way), whilst the remainder of the mass formed the central bodj r of the whole system, the sun. This is, in a few words, the view of the evolution of our solar system which is known as the Kant-Laplace theory. In favour of this a large number of astronomical and physical facts are quoted, such as the agreement in the direction of motion of all the planets, and the (nearly complete) coincidence of the planes of their orbits ; also the existence of the ring of Saturn and the gradual increase in density of the planets as we approach towards the sun, and also the increase in density of each from without inwards. 1 For other still weightier evidence we have to thank the spectral analysis of our sun and of other heavenly bodies. This has shown that (1) certain of them, the so-called nebulae, are huge masses consisting entirely of glowing gas ; (2) others, the so-called suns (including our sun), are bodies in which, owing to the long- continued loss of heat, and the consequent contraction of their mass, a fluid core has been formed they consist of an inner glow- ing fluid part and an outer envelope of gas : lastly (3) a third kind, in consequence of still further cooling, have become solid and with this have lost their power of giving light. To this last kind of 1 This has been proved not only for the earth, but also for Jupiter. INTRODUCTION. 1 1 bodies belongs our -earth, together with the other planets and their satellites, as well as certain dark stars of other systems. Tims we now know that examples of all the chief stages which the theory of Laplace requires for the full development of a celes- tial body (namely, 1. the original gas ball ; 2. the gas ball with liquid centre ; 3. the solidified mass), are now found, and this fact gives to the theory so high a degree of probability that we may consider it as certain. If this was the mode of evolution of all celestial bodies, we are obliged to conclude that in a far distant time our earth also was a liquid, light-giving globe, which at a later period became covered with a solid crust ; and this idea is in the most complete accord, not only with the old conclusion derived from purely geological facts, but also with the results of the latest observations of astronomical physics. According to the above views, the idea of an original crust formed by solidification is absolutely necessary. Moreover, some such conclusion is unavoidable, since the oldest sediments require a foundation on which they may be laid, and the oldest eruptive rocks require a crust through which to break. Nor must we for- get that the first sediments, whether of chemical or mechanical origin, necessarily presuppose an older already present rock from the chemical or mechanical destruction of which they might be formed ; and this material can have been furnished only by the crust formed by the solidification of the glowing liquid mass of the earth. Since the idea of a solidification crust, although it was once con- sidered a mere picture of the fancy, is an absolute necessity, the question arises whether there are anywhere any rocks which ma} r be pointed out with more or less probability as the remains of this- crust. If such an origin may be admitted for any rock, there is none of which it is so likely to be true as gneiss, which as will be shown extends with wonderful regularity as the deepest known rock on the whole earth. If this view cannot be ac- cepted, it must yet be admitted that when we wish to form a picture of the constitution of the oldest rocks of the earth, we ar& forced to represent them to ourselves as more or less gneiss-like. For it may reasonably be considered that the material of the crust would not be very different from the oldest eruptive rocks ; and these are of granite, which differs from gneiss only in structure. It has also been correctly remarked that if we could melt together 12 INTRODUCTION. all the rocks of the present crust of the earth, we should have a rock approximately like that which formed the original solidifica- tion crust ; and that in that case we should have an acid silicate is beyond question, on account of the extraordinarily wide distri- bution of quartz. Moreover, since the eruptive rocks of later ages have risen from continually increasing depths, where probably a mixture more basic than at the surface is collected, they have thus become more and more basic ; and such a smelting product would therefore be more basic than the original crust. If we consider the great density of the interior of the earth (which depends on the fact that when the earth was fluid, the materials composing it arranged themselves according to their specific gravity), it is clear that we can scarcely be far wrong if we suppose that the first crust would consist of those minerals the chemical constituents of which were the lightest. To these would belong (besides those combinations which remained in the state of vapour, such as carbonic acid, water, and several others) silica, alumina, the alkalies, and a part of the alkaline earths. But these are all constituents of those minerals which form gneiss (quartz, mica, felspar). The condition of the earth after the formation of the crust can only be briefly indicated. With the progressive cooling, a gradual contraction of the earth must have gone hand in hand ; and with this a constantly repeated tearing open, cracking, and dismember- ing of the first formed crust. From these rents and cracks the glowing interior pressed forth in huge masses to unite by their solidification as a cement the broken pieces of the crust. It is clear that in those remote times, owing to the great heat of the air, no water could exist in a liquid state ; and it was not till the temperature had fallen greatly that a covering of water could form around the solid centre. Moreover, this primitive sea, when first formed, lay under the pressure of an atmosphere much denser than the present, which still contained the whole of the carbonic acid and probably other matters also. It must therefore have possessed a very high temperature, far above the boiling point of water at ordinary pressures ; so that it did not yet offer the necessary conditions for the development of organisms, and it was not till a still later period that the earth became cool enough for the first appearance of life. I. ARCHAEAN OR PRIMITIVE ROCKS. GENERAL CHARACTERS AND COMPOSITION OF THE ARCHAEAN ROCKS. UNDER the head of Archsean we group together all those rocks which are older than the lowest beds of the Cambrian, and which extend from these as their upper limit to the deepest, so-called Laurentian, gneiss. The terms fundamental or Primitive (terrain primitif of the French) Azoic or Agnotozoic, and Pre-Cambrian have also been used with the same signification. The Archsean are the oldest known rocks that reach the sur- face where the foundation of the oldest fossil-bearing beds has been laid bare by erosion, denudation or dislocations. They are the base on which have been laid the oldest as well as all the later sediments. The Archsean rocks as a whole form an extremely large mass one may well say the most important of all the rock-masses taking part in the formation of the earth's crust. Although it is very difficult, in consequence of the very disturbed condition of these primitive beds, to determine their thickness even approxim- ately, yet there is no doubt that where they are fully developed they are many tens of thousands of feet thick. The total thick- ness of the Archsean in N. America has been estimated at 50,000 feet, and in Bohemia at 100,000. The period of time occupied by the formation of these rocks must, in correspondence with their great thickness, have been of extraordinary length, probably so long that the beginning of the Cambrian period may be considered as comparatively a recent event. The Archaean is not only the oldest and thickest, but also by far the most wide-spread of all the formations of the earth's crust. It is found in Bohemia and the Alps, in Scandinavia and Canada, in the Himalayas and Andes, in short in all continents and in all latitudes. In several regions, as in Arctic N. America is 14 I. ARCHAEAN OR PRIMITIVE ROCKS. nnd in Central Africa, it occupies thousands of square miles with- out any covering of later rocks. But even where the surface is occupied by younger beds one may take it for granted that the Archaean rocks are continued without interruption, so that any boring, if only it be made deep enough, would at length strike the Primitive rocks. The Primitive group is the only series which .-covers the whole earth like a shell, the only one which has justly been spoken of as ubiquitous ; whilst on the other hand all the later normal sedimentary formations have a limited distribution .and lie round the earth, as has been aptly remarked, like the leaves of a rose-bud. The extraordinary thickness and universal extent of the Archaean rocks strongly distinguishes them from all the younger beds. But a much more important difference still is to be found in their crystalline character and the absence of fossils. The first peculiarity is the one which gives to the rocks belong- ing to the series the name of " crystalline schists." We know in- deed that even among the younger formations crystalline schists occur more or less like those of the Archaean ; but the great mass of the crystalline schists belongs to the Archaean, so that the two terms are usually of equal signification. The widest spread and at the same time most characteristic of the crystalline schists is Gneiss, which like granite is a crystalline mixture of quartz, felspar, and mica, but differs from it in being, not of a granular, but of a schistose structure. It is divided into two chief varieties, mica- and hornblende- gneiss, of which the first is again divisible into red (Muscovite) and grey (Biotite) gneiss. In close connec- tion with these varieties come numerous allied rocks, such as Granulite, Protogine, Halleflinta, etc. Another, very important and wide-spread type is Mica schist, consisting essentially of mica .and quartz, with which numerous accessory minerals ma}' be associated. Chlorite, Hornblende, Sericite, Talc, Quartzite, Haema- tite, and Graphite schists, and other allied schistose rocks are very common companions of mica schist. Lastly, the third chief type is Phyllite, which agrees in composition with mica schist but appears denser in structure, and has been aptly defined as a microscopic mica schist. All the various rocks ascribed to the Phyllites possess, on account of their high percentage of mica, a peculiar silky lustre. Along with these types of rocks, which are characterized without exception by a schistose structure, there occur a number of more massive crystalline rocks such as Gneissic- I. ARCHAEAN OR PRIMITIVE ROCKS. 15 granite, Eklogite, Granite, etc., and especially crystalline lime- stone, which is of frequent occurrence in the form of lenticular interbedded masses in all Archaean regions. That the parallel structure and foliation of the crystalline schists is, like all foliation, due to pressure, is universally agreed. But the explanation of the tabular and bed-like structure observed in almost all crystalline schists a structure which is usually, but by no means always, parallel to the foliation is very doubtful. On ac- count of the fact that each layer usually possesses its own lithological character they have generally been regarded as true beds. But cases are known where the foliation of the gneiss little by little passes in- to tabular structure, and others where the different and successive layers of gneiss and mica schist have been cut through by a bed- ding which does not coincide with their foliation ; and hence it ap- pears that no single explanation is applicable in all cases ; the platy structure, like the foliation, may in many cases be the result of pressure. The Archaean, rocks must be considered unfossiliferous, since it has been shown that the supposed fossils found towards the middle of the century in Canada and afterwards in Scotland, Scandinavia and Bohemia, are of inorganic origin. These supposed fossils occur in crystalline limestone in the gneiss and form nodular masses consisting chiefly of jserpentinons Tnnt.p.n'n.1 divide^ -*>y numerous tubes swejlin^ jmt_iiita cells. They were described as ^iTrnTTTor^minifers under the name Eozoon, but have been shown, thanks especially to the minute microscopic researches of Mobius, to be inorganic. On account of this absence of fossils the name Azoic (first used by Murchison in 1845 for the old crystalline mass of Scandinavia) has been applied to these rocks. Some observers indeed have thought that the occurrence of limestone and graphite in the Archaean is an indication of the existence of organic life ; and they have pointed to the great importance of organisms in the formation of limestone, and have looked upon graphite as the final product of change of the vegetable matter. Against this view, which has occasioned the use of the terms eozoic, agnotozoic, etc., it may be objected that limestone as well as graphite can certainly be formed inorganically ; the latter, for example, separates out in the casting of pig-iron. The strongest evidence of the existence of organized life during the Archaean period, is to be found in the relatively high organization of the oldest known fauna, the Cambrian. The high development of this fauna indeed necessarily Ib I. ARCHAEAN OR PRIMITIVE ROCKS. forces us to the conclusion that it was preceded by one. or more, probably a whole series, of older faunas, the remains of which we may expect in time to find in the Archaean. So long, however, as such remains have not been found, it is advisable, instead of the as yet unwarranted term Eozoic, to keep to the expression Archaean introduced by Dana (1874). With respect to the composition of the Archaean rocks it has already been mentioned that they are built up essentially of crystalline schists with the three chief varieties, Gneiss, Mica schist and Pl^llite. But it must still be noticed that besides these there occur in the upper part of the series more or less clearly clastic rocks such as quartzite, sandstone, and haematite FIG. 1. Section near Wolmersdorf in Lower Austria (v. Hauer). 1. Quartzite Schist. 2. Granular Limestone. 3. Hornblende Schist. 4. Mica Schist. I.-IV. Beds of Graphite. a 6 c