Chapter I: Part 1

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THE
WORLD BEFORE THE DELUGE.

BY
_LOUIS FIGUIER_.

NEWLY EDITED AND REVISED
BY
H. W. BRISTOW, F.R.S., F.G.S.,

_Of the Geological Survey of Great Britain; Hon. Fellow of King’s
College, London._

With 235 Illustrations.

CASSELL, PETTER, & GALPIN,
LONDON, PARIS, AND NEW YORK.

CONTENTS.

PAGE

GENERAL CONSIDERATIONS 1
CONSIDERATION OF FOSSILS 4
CHEMICAL AND NEBULAR HYPOTHESES OF THE GLOBE 15
MODIFICATIONS OF THE EARTH’S SURFACE 26
ERUPTIVE ROCKS 30
PLUTONIC ERUPTIONS 31
Granite 31
Syenite 34
Protogine 35
Porphyry 37
Serpentine 38
VOLCANIC ROCKS 39
Trachytic Formations 39
Basaltic Formations 44
Volcanic or Lava Formations 51
METAMORPHIC ROCKS 71
General Metamorphism 74
THE BEGINNING 80
PRIMARY EPOCH 99
CAMBRIAN PERIOD 101
SILURIAN PERIOD 102
Lower Silurian Period 104
Upper Silurian Period 110
OLD RED SANDSTONE AND DEVONIAN PERIOD 119
CARBONIFEROUS PERIOD 130
Carboniferous Limestone 140
Coal Measures 150
Formation of Coal 159
PERMIAN PERIOD 170
Permian Rocks 177
SECONDARY EPOCH 185
TRIASSIC, OR NEW RED PERIOD 185
New Red Sandstone 187
Muschelkalk 188
Keuper Period 199
RHÆTIC (PENARTH) PERIOD 207
JURASSIC PERIOD 211
Liassic Period 211
Oolitic Sub-Period 243
Lower Oolite Fauna 244
---- ---- Rocks 249
Middle Oolite 255
Upper Oolite 265
CRETACEOUS PERIOD 275
Lower Cretaceous Period 286
Upper Cretaceous Period 300
TERTIARY EPOCH 312
Eocene Period 315
Miocene Period 336
Pliocene Period 357
QUATERNARY EPOCH 378
POST-PLIOCENE 378
EUROPEAN DELUGES 422
GLACIAL PERIOD 435
CREATION OF MAN 464
ASIATIC DELUGE 480
EPILOGUE 489
TABLE AND DIAGRAM OF BRITISH SEDIMENTARY AND FOSSILIFEROUS
STRATA 493

FULL-PAGE ILLUSTRATIONS.

FRONTISPIECE--THE FIRST MAN.
PAGE
I. De Sancy Peak, Mont Dore 42
II. Basaltic Mountain of La Coupe d’Ayzac 46
III. Extinct Volcanoes of Le Puy 52
IV. Mud Volcano of Turbaco 62
V. Great Geyser of Iceland 66
VI. The Earth in a gaseous state circulating in space 82
VII. Condensation and rainfall 94
VIII. Ideal Landscape of the Silurian Period 104
IX. Ideal Landscape of the Devonian Period 121
X. Ideal view of marine life in the Carboniferous
Period 147
XI. Ideal view of a marshy forest in the Coal Period 156
XII. Ideal Landscape of the Permian Period 172
XIII. Ideal Landscape of the Muschelkalk Period 191
XIV. Ideal Landscape of the Saliferous or Keuper Period 198
XV. Ideal Scene of the Lias Period with Ichthyosaurus
and Plesiosaurus 231
XVI. Ideal Landscape of the Liassic Period 241
XVII. Ideal Landscape of the Lower Oolite Period 254
XVIII. Ideal Landscape of the Middle Oolite Period 258
XIX. Apiocrinites rotundus and Encrinus liliiformis 261
XX. Ideal Landscape of the Upper Oolite Period 267
XXI. Ideal Scene of the Lower Cretaceous Period 296
XXII. Ideal Landscape of the Cretaceous Period 307
XXIII. Ideal Landscape of the Eocene Period 328
XXIV. Ideal Landscape of the Miocene Period 352
XXV. Ideal Landscape of the Pliocene Period 375
XXVI. Skeleton of the Mammoth in the St. Petersburg
Museum 394
XXVII. Skeleton of Megatherium 403
XXVIII. Ideal View of the Quaternary Epoch--Europe 416
XXIX. Ideal Landscape of the Quaternary Epoch--America 419
XXX. Deluge of the North of Europe 425
XXXI. Glaciers of Switzerland 445
XXXII. Appearance of Man 468
XXXIII. Asiatic Deluge 483
DIAGRAM AT END--Ideal Section of the Earth’s Crust, showing the
order of superposition or chronological succession of
the principal groups of strata.

PREFACE.

The object of “The World before the Deluge” is to trace the progressive steps by which the earth has reached its present state, from that condition of chaos when it “was without form and void, and darkness was upon the face of the deep,” and to describe the various convulsions and transformations through which it has successively passed. In the words of the poet--

“Where rolls the deep, there grew the tree;
O Earth, what changes hast thou seen!
There, where the long street roars, hath been
The silence of the central sea.”

It has been thought desirable that the present edition of the work should undergo a thorough revision by a practical geologist, a task which Mr. H. W. Bristow has performed. Mr. Bristow has however confined himself to such alterations as were necessary to secure accuracy in the statement of facts, and such additions as were necessary to represent more precisely the existing state of scientific opinion. Many points which are more or less inferential and therefore matters of individual opinion, and especially those on which M. Figuier bases his speculations, have been left in their original form, in preference to making modifications which would wholly change the character of the book. In a work whose purpose is to give the general reader a summarised account of the results at which science has arrived, and of the method of reasoning regarding the facts on which these generalisations rest, it would be out of place, as well as ineffective, to obscure general statements with those limitations which caution imposes on the scientific investigator.

In the original work the Author had naturally enough drawn most of his facts from French localities; in the translation these are mostly preserved, but others drawn from British Geology have been added, either from the translator’s own knowledge, or from the works of well-known British writers. It was considered desirable, for similar reasons, to enlarge upon the opinions of British geologists, to whom the French work scarcely does justice, considering the extent to which the science is indebted to them for its elucidation.

In the original work the chapter on Eruptive Rocks comes at the end of the work, but, as the work proceeded, so many unexplained allusions to that chapter were found that it seemed more logical, and more in accordance with chronological order, if the expression may be used, to place that chapter at the beginning.

A new edition of the French work having appeared in the early part of 1866, to which the Author contributed a chapter on Metamorphic Rocks, a translation of it is appended to the chapter on Eruptive Rocks.

A chapter on the Rhætic (or Penarth) beds has been inserted (amongst much other original matter), the stratigraphical importance of that series having been recognised since the publication of the First Edition.

In the present Edition the text has been again thoroughly revised by Mr. Bristow, and many important additions made, the result of the recent investigations of himself and his colleagues of the Geological Survey.

THE
WORLD BEFORE THE DELUGE.

GENERAL CONSIDERATIONS.

The observer who glances over a rich and fertile plain, watered by rivers and streams which have, during a long series of ages, pursued the same uniform and tranquil course; the traveller who contemplates the walls and monuments of a great city, the first founding of which is lost in the night of ages, testifying, apparently, to the unchangeableness of things and places; the naturalist who examines a mountain or other locality, and finds the hills and valleys and other accidents of the soil in the very spot and condition in which they are described by history and tradition--none of these observers would at first suspect that any serious change had ever occurred to disturb the surface of the globe. Nevertheless, the earth has not always presented the calm aspect of stability which it now exhibits; it has had its convulsions, and its physical revolutions, whose story we are about to trace. The earth, like the body of an animal, is wasted, as the philosophical Hutton tells us, at the same time that it is repaired. It has a state of growth and augmentation; it has another state, which is that of diminution and decay: it is destroyed in one part to be renewed in another; and the operations by which the renewal is accomplished are as evident to the scientific eye as those by which it is destroyed. A thousand causes, aqueous, igneous, and atmospheric, are continually at work modifying the external form of the earth, wearing down the older portions of its surface, and reconstructing newer out of the older; so that in many parts of the world denudation has taken place to the extent of many thousand feet. Buried in the depths of the soil, for example, in one of those vast excavations which the intrepidity of the miner has dug in search of coal or other minerals, there are numerous phenomena which strike the mind of the inquirer, and carry their own conclusions with them. A striking increase of temperature in these subterranean places is one of the most remarkable of these. It is found that the temperature of the earth rises one degree for every sixty or seventy feet of descent from its surface. Again: if the mine be examined vertically, it is found to consist of a series of layers or beds, sometimes horizontal, but more frequently inclined, upright, or contorted and undulating--even folded back upon themselves. Then, instances are numerous where horizontal and parallel beds have been penetrated, and traversed vertically or obliquely by veins of ores or minerals totally different in their appearance and nature from the surrounding rocks. All these undulations and varying inclinations of strata are indications that some powerful cause, some violent mechanical action, has intervened to produce them. Finally, if the interior of the beds be examined more minutely--if, armed with the miner’s pick and hammer, the rock is carefully broken up--it is not impossible that the very first efforts at mining may be rewarded by the discovery of some fossilised organic form no longer found in the living state. The remains of plants and animals belonging to the earlier ages of the world, are, in fact, very common; entire strata are sometimes formed of them; and in some localities the rocks can scarcely be disturbed without yielding fragments of bones and shells, or the impressions of fossilised animals and vegetables--the buried remains of extinct creations.

These bones--these remains of animals or vegetables which the hammer of the geologist has torn from the rock--belong possibly to some organism which no longer any where exists: it may not be identical with any animal or plant living in our times: but it is evident that these beings, whose remains are now so deeply buried, have not always been so covered; they once lived on the surface of the earth as plants and animals do in our days, for their organisation is essentially the same. The beds in which they now repose must, then, in older times have formed the surface of the earth; and the presence of these fossils proves that the earth has suffered great mutations at some former period of its history.

Geology explains to us the various transformations which the earth has passed through before it arrived at its present condition. We can determine, with its help, the comparative epoch to which any beds belong, as well as the order in which others have been superimposed upon them. Considering that the stratigraphical crust of the earth with which the geologist has to deal may be some ten miles thick, and that it has been deposited in distinct layers in a definite order of succession, the dates or epochs of each formation may well be approached with hesitation and caution.

Dr. Hutton, the earliest of our philosophical geologists, eloquently observes, in his “Theory of the Earth,” that the solid earth is everywhere wasted at the surface. The summits of the mountains are necessarily degraded. The solid and weighty materials of these mountains have everywhere been carried through the valleys by the force of running water. The soil which is produced in the destruction of the solid earth is gradually transported by the moving waters, and is as constantly supplying vegetation with its necessary aid. This drifted soil is at last deposited upon some coast, where it forms a fertile country. But the billows of the ocean again agitate the loose material upon the shore, wearing away the coast with endless repetitions of this act of power and imparted force; the solid portion of our earth, thus sapped to its foundations, is carried away into the deep and sunk again at the bottom of the sea whence it had originated, and from which sooner or later it will again make its appearance. We are thus led to see a circulation of destruction and renewal in the matter of which the globe is formed, and a system of beautiful economy in the works of Nature. Again, discriminating between the ordinary and scientific observer, the same writer remarks, that it is not given to common observation to see the operation of physical causes. The shepherd thinks the mountain on which he feeds his flock has always been there. The inhabitant of the valley cultivates the soil as his fathers did before him, and thinks the soil coeval with the valley or the mountain. But the scientific observer looks into the chain of physical events, sees the great changes that have been made, and foresees others that must follow from the continued operation of like natural causes. For, as Pythagoras taught 2,350 years ago, “the minerals and the rocks, the islands and the continents, the rivers and the seas, and all organic Nature, are perpetually changing; there is nothing stationary on earth.” To note these changes--to decipher the records of this system of waste and reconstruction, to trace the physical history of the earth--is the province of GEOLOGY, which, the latest of all modern sciences, is that which has been modified most profoundly and most rapidly. In short, resting as it does on observation, it has been modified and transformed according to every series of facts recorded; but while many of the facts of geology admit of easy and obvious demonstration, it is far otherwise with the inferences which have been based upon them, which are mostly hypothetical, and in many instances from their very nature incapable of proof. Its applications are numerous and varied, projecting new and useful lights upon many other sciences. Here we ask of it the teachings which serve to explain the origin of the globe--the evidence it furnishes of the progressive formation of the different rocks and mineral masses of which the earth is composed--the description and restoration of the several species of animals and vegetables which have existed, have died and become extinct, and which form, in the language of naturalists, the _Fauna_ and _Flora_ of the ancient world.

* * * * *

In order to explain the origin of the earth, and the cause of its various revolutions, modern geologists invoke three orders of facts, or fundamental considerations:

I. The hypothesis of the original incandescence of the globe.

II. The consideration of fossils.

III. The successive deposition of the sedimentary rocks.

As a corollary to these, the hypothesis of the upheaval of the earth’s crust follows--upheavals having produced local revolutions. The result of these upheavals has been to superimpose new materials upon the older rocks, introducing extraneous rocks called _Eruptive_, beneath, upon, and amongst preceding deposits, in such a manner as to change their nature in divers ways. Whence is derived a third class of rocks called _Metamorphic_ or altered _rocks_, our knowledge of which is of comparatively recent date.

FOSSILS.

The name of _Fossil_ (from _fossilis_, dug up) is given to all organised bodies, animal or vegetable, buried naturally in the terrestrial strata, and more or less petrified, that is, converted into stone. Fossils of the older formations are remains of organisms which, so far as species is concerned, are quite extinct; and only those of recent formations belong to genera living in our days. These fossil remains have neither the beauty nor the elegance of most living species, being mutilated, discoloured, and often almost shapeless; they are, therefore, interesting only in the eyes of the observer who would interrogate them, and who seeks to reconstruct, with their assistance, the Fauna and Flora of past ages. Nevertheless, the light they throw upon the past history of the earth is of the most satisfactory description, and the science of fossils, or palæontology, is now an important branch of geological inquiry. Fossil shells, in the more recent deposits, are found scarcely altered; in some cases only an impression of the external form is left--sometimes an entire cast of the shell, exterior and interior. In other cases the shell has left a perfect impression of its form in the surrounding mud, and has then been dissolved and washed away, leaving only its mould. This mould, again, has sometimes been filled up by calcareous spar, silica, or pyrites, and an exact cast of the original shell has thus been obtained. Petrified wood is also of very common occurrence.

These remains of an earlier creation had long been known to the curious, and classed as _freaks of Nature_, for so we find them described in the works of the ancient philosophers who wrote on natural history, and in the few treatises on the subject which the Middle Ages have bequeathed to us. Fossil bones, especially those of elephants, were known to the ancients, giving rise to all sorts of legends and fabulous histories: the tradition which attributed to Achilles, to Ajax, and to other heroes of the Trojan war, a height of twenty feet, is attributable, no doubt, to the discovery of the bones of elephants near their tombs. In the time of Pericles we are assured that in the tomb of Ajax a _patella_, or knee-bone of that hero, was found, which was as large as a dinner-plate. This was probably only the patella of a fossil elephant.

The uses to which fossils are applied by the geologist are--First, to ascertain the relative age of the formations in which they occur; secondly, the conditions under which these were deposited. The age of the formation is determined by a comparison of the fossils it contains with others of ascertained date; the conditions under which the rocks were deposited, whether marine, lacustrine, or terrestrial, are readily inferred from the nature of the fossils. The great artist, Leonardo da Vinci, was the first to comprehend the real meaning of fossils, and Bernard Palissy had the glory of being the first modern writer to proclaim the true character of the fossilised remains which are met with, in such numbers, in certain formations, both in France and Italy, particularly in those of Touraine, where they had come more especially under his notice. In his work on “Waters and Fountains,” published in 1580, he maintains that the _figured stones_, as fossils were then called, were the remains of organised beings preserved at the bottom of the sea. But the existence of marine shells upon the summits of mountains had already arrested the attention of ancient authors. Witness Ovid, who in Book XV. of the “Metamorphoses” tells us he had seen land formed at the expense of the sea, and marine shells lying dead far from the ocean; and more than that, an ancient anchor had been found on the very summit of a mountain.

“Vidi factas ex æquore terras,
Et procul a pelago conchæ jacuere marinæ,
Et vetus inventa est in montibus anchora summis.”

Ov., _Met._, Book xv.

The Danish geologist Steno, who published his principal works in Italy about the middle of the seventeenth century, had deeply studied the fossil shells discovered in that country. The Italian painter Scilla produced in 1670 a Latin treatise on the fossils of Calabria, in which he established the organic nature of fossil shells.

The eighteenth century gave birth to two very opposite theories as to the origin of our globe--namely, the _Plutonian_ or igneous, and the _Neptunian_ or aqueous theory. The Italian geologists gave a marked impulse to the study of fossils, and the name of Vallisneri[1] may be cited as the author to whom science is indebted for the earliest account of the marine deposits of Italy, and of the most characteristic organic remains which they contain. Lazzaro Moro[2] continued the studies of Vallisneri, and the monk Gemerelli reduced to a complete system the ideas of these two geologists, endeavouring to explain all the phenomena as Vallisneri had wished, “without violence, without fiction, without miracles.” Marselli and Donati both studied in a very scientific manner the fossil shells of Italy, and in particular those of the Adriatic, recognising the fact that they affected in their beds a regular and constant order of superposition.[3]

[1] Dei corpi marini, &c., 1721.

[2] Sui crostaccei ed altri corpi marini che sè trovano sui monti,
1740.

[3] Consult Lyell’s “Principles of Geology” and the sixth edition of
the “Elements,” with much new matter, for further information
relative to the study of fossils during the last two centuries.

In France the celebrated Buffon gave, by his eloquent writings, great popularity to the notions of the Italian naturalists concerning the origin of fossil remains. In his admirable “Époques de la Nature” he sought to prove that the shells found in great quantities buried in the soil, and even on the tops of mountains, belonged, in reality, to species not living in our days. But this idea was too novel not to find objectors: it counted among its adversaries the bold philosopher who might have been expected to adopt it with most ardour. Voltaire attacked, with his jesting and biting criticism, the doctrines of the illustrious innovator. Buffon insisted, reasonably enough, that the presence of shells on the summit of the Alps was a proof that the sea had at one time occupied that position. But Voltaire asserted that the shells found on the Alps and Apennines had been thrown there by pilgrims returning from Rome. Buffon might have replied to his opponent, by pointing out whole mountains formed by the accumulation of these shells. He might have sent him to the Pyrenees, where shells of marine origin cover immense areas to a height of 6,600 feet above the present sea-level. But his genius was averse to controversy; and the philosopher of Ferney himself put an end to a discussion in which, perhaps, he would not have had the best of the argument. “I have no wish,” he wrote, “to embroil myself with Monsieur Buffon about shells.”

It was reserved for the genius of George Cuvier to draw from the study of fossils the most wonderful results: it is the study of these remains, in short, which, in conjunction with mineralogy, constitutes in these days positive geology. “It is to fossils,” says the great Cuvier, “that we owe the discovery of the true theory of the earth; without them we should not have dreamed, perhaps, that the globe was formed at successive epochs, and by a series of different operations. They alone, in short, tell us with certainty that the globe has not always had the same envelope; we cannot resist the conviction that they must have lived on the surface of the earth before being buried in its depths. It is only by analogy that we have extended to the primary formations the direct conclusions which fossils furnish us with in respect to the secondary formations; and if we had only unfossiliferous rocks to examine, no one could maintain that the earth was not formed all at once.”[4]

[4] “Ossements Fossiles” (4to), vol. i., p. 29.

The method adopted by Cuvier for the reconstruction and restoration of the fossil animals found in the plaster-quarries of Montmartre, at the gates of Paris, has served as a model for all succeeding naturalists; let us listen, then, to his exposition of the vast problem whose solution he proposed to himself. “In my work on fossil bones,” he says, “I propose to ascertain to what animals the osseous fragments belong; it is seeking to traverse a road on which we have as yet only ventured a few steps. An antiquary of a new kind, it seemed to me necessary to learn both to restore these monuments of past revolutions, and to decipher their meaning. I had to gather and bring together in their primitive order the fragments of which they are composed; to reconstruct the ancient beings to which these fragments belonged; to reproduce them in their proportions and with their characteristics; to compare them, finally, with others now living on the surface of the globe: an art at present little known, and which supposes a science scarcely touched upon as yet, namely, that of the laws which preside over the co-existence of the forms of the several parts in organised beings. I must, then, prepare myself for these researches by others, still more extended, upon existing animals. A general review of actual creation could alone give a character of demonstration to my account of these ancient inhabitants of the world; but it ought, at the same time, to give me a great collection of laws, and of relations not less demonstrable, thus forming a body of new laws to which the whole animal kingdom could not fail to find itself subject.”[5]

[5] “Ossements Fossiles” (4to), vol. i., pp. 1, 2.

“When the sight of a few bones inspired me, more than twenty years ago, with the idea of applying the general laws of comparative anatomy to the reconstruction and determination of fossil species; when I began to perceive that these species were not quite perfectly represented by those of our days, which resembled them the most--I no longer doubted that I trod upon a soil filled with spoils more extraordinary than any I had yet seen, and that I was destined to bring to light entire races unknown to the present world, and which had been buried for incalculable ages at great depths in the earth.

“I had not yet given any attention to the published notices of these bones, by naturalists who made no pretension to the recognition of their species. To M. Vaurin, however, I owe the first intimation of the existence of these bones, with which the gypsum-quarries swarm. Some specimens which he brought me one day struck me with astonishment; I learned, with all the interest the discovery could inspire me with, that this industrious and zealous collector had already furnished some of them to other collectors. Received by these amateurs with politeness, I found in their collections much to confirm my hopes and heighten my curiosity. From that time I searched in all the quarries with great care for other bones, offering such rewards to the workmen as might awaken their attention. I soon got together more than had ever been previously collected, and after a few years I had nothing to desire in the shape of materials. But it was otherwise with their arrangement, and with the reconstruction of the skeleton, which could alone lead to any just idea of the species.

“From the first moment of discovery I perceived that, in these remains, the species were numerous. Soon afterwards I saw that they belonged to many genera, and that the species of the different genera were nearly the same size, so that size was likely rather to hinder than aid me. Mine was the case of a man to whom had been given at random the mutilated and imperfect remains of some hundreds of skeletons belonging to twenty sorts of animals; it was necessary that each bone should find itself alongside that to which it ought to be connected: it was almost like a small resurrection, and I had not at my disposal the all-powerful trumpet; but I had the immutable laws prescribed to living beings as my guide; and at the voice of the anatomist each bone and each part of a bone took its place. I have not expressions with which to describe the pleasure I experienced in finding that, as soon as I discovered the character of a bone, all the consequences of the character, more or less foreseen, developed themselves in succession: the feet were found conformable to what the teeth announced; the teeth to that announced by the feet; the bones of the legs, of the thighs, all those which ought to reunite these two extreme parts, were found to agree as I expected; in a word, each species was reproduced, so to speak, from only one of its elements.”[6]

[6] “Ossements Fossiles,” vol. iv. (4to), p. 32.

While the Baron Cuvier was thus zealously prosecuting his inquiries in France, assisted by many eminent fellow-labourers, what was the state of geological science in the British Islands? About that same time, Dr. William Smith, better known as “the father of English geology,” was preparing, unaided, the first geological map of this country. Dr. Smith was a native of Wiltshire, and a canal engineer in Somersetshire; his pursuits, therefore, brought him in the midst of these hieroglyphics of Nature. It was his practice, when travelling professionally, during many years to consult masons, miners, wagoners, and agriculturists. He examined the soil; and in the course of his inquiries he came to the conclusion that the earth was not all of the same age; that the rocks were arranged in layers, or strata, superimposed on each other in a certain definite order, and that the strata, when of the same age, could be identified by means of their organic remains. In 1794 he formed the plan of his geological map, showing the superposition of the various beds; for a quarter of a century did he pursue his self-allotted task, which was at last completed, and in 1801 was published, being the first attempt to construct a stratigraphical map.

Taking the men in the order of the objects of their investigation, rather than in chronological order, brings before us the patient and sagacious investigator to whom we are indebted for our knowledge of the Silurian system. For many years a vast assemblage of broken and contorted beds had been observed on the borders of North Wales, stretching away to the east as far as Worcestershire, and to the south into Gloucester, now rising into mountains, now sinking into valleys. The ablest geologists considered them as a mere labyrinth of ruins, whose order of succession and distinctive organic remains were entirely unknown, “But a man came,” as M. Esquiros eloquently writes, “who threw light upon this sublime confusion of elements.” Sir Roderick Impey Murchison, then a young President of the Geological Society, had his attention directed, as he himself informs us, to some of these beds on the banks of the Wye. After seven years of unremitting labour, he was rewarded by success. He established the fact that these sedimentary rocks, penetrated here and there by eruptive masses of igneous origin, formed a unique system, to which he gave the name of _Silurian_, because the rocks which he considered the most typical of the whole were most fully developed, charged with peculiar organic remains, in the land of the ancient Silures, who so bravely opposed the Roman invaders of their country. Many investigators have followed in Sir Roderick’s steps, but few men have so nobly earned the honours and fame with which his name is associated.

The success which attended Sir R. Murchison’s investigations soon attracted the attention of other geologists. Professor Sedgwick examined the older slaty strata, and succeeded in proving the position of the Cambrian rocks to be at the base of the Silurian. Still it was reserved for Sir William Logan, the Director of the Canadian Geological Survey, to establish the fact that immense masses of gneissic formation lay at the base of the Cambrian; and, by subsequent investigations, Sir Roderick Murchison satisfied himself that this formation was not confined to Canada, but was identical with the rocks termed by him Fundamental Gneiss, which exist in enormous masses on the west coast of Scotland, and which he proved to be the oldest stratified rocks in the British Isles. Subsequently he demonstrated the existence of these same Laurentian rocks in Bohemia and Bavaria, far beneath the Silurian rocks of Barrande.

While Murchison and Sedgwick were prosecuting their inquiries into the Silurian rocks, Hugh Miller and many others had their attention occupied with the Old Red Sandstone--the Devonian of Sedgwick and Murchison--which immediately overlies them. After a youth passed in wandering among the woods and rocks of his native Cromarty, the day came when Miller found himself twenty years of age, and, for the time, a workman in a quarry. A hard fate he thought it at the time, but to him it was the road to fame and success in life. The quarry in which he laboured was at the bottom of a bay formed by the mouth of a river opening to the south, a clear current of water on one side, as he vividly described it, and a thick wood on the other. In this silent spot, in the remote Highlands, a curious fossil fish of the Old Red Sandstone was revealed to him; its appearance struck him with astonishment; a fellow-workman named a spot where many such monuments of a former world were scattered about; he visited the place, and became a geologist and the historian of the “Old Red.” And what strange fantastic forms did it afterwards fall to his lot to describe! “The figures on a China vase or Egyptian obelisk,” he says, “differ less from the real representation of the objects than the fossil fishes of the ‘Old Red’ differ from the living forms which now swim in our seas.”

The _Carboniferous Limestone_, which underlies the coal, the _Coal-measures_ themselves, the _New Red Sandstone_, the _Lias_, and the _Chalk_, have in their turn found their historians; but it would be foreign to our object to dwell further here on these particular branches of the subject.

Some few of the fossilised beings referred to resemble species still found living, but the greater part belong to species which have become altogether extinct. These fossil remains may constitute natural families, none of the genera of which have survived. Such is the _Pterodactyle_ among Pterosaurian reptiles; the _Ammonite_ among Mollusca; the _Ichthyosaurus_ and the _Plesiosaurus_ among the Enaliosaurian reptiles. At other times there are only extinct genera, belonging to families of which there are still some genera now living, as the genus _Palæoniscus_ among fishes. Finally, in Tertiary deposits, we meet with some extinct species belonging to genera of our existing fauna: the _Mammoth_, for example, of the youngest Tertiary deposits, is an extinct species of the genus elephant.

Some fossils are terrestrial, like the gigantic Irish stag, _Cervus Megaceros_, the snail or _Helix_; fluviatile or lacustrine, like the _Planorbis_, the _Lymnæa_, the _Physa_, and the _Unio_; marine, or inhabiting the sea exclusively, as the Cowry (_Cypræa_), and the Oyster, (_Ostrea_).

Fossils are sometimes preserved in their natural state, or are but very slightly changed. Such is the state of some of the bones extracted from the more recent caves; such, also, is the condition of the insects found enclosed in the fossil resins in which they have been preserved from decomposition; and certain shells, found in recent and even in old formations, such as the Jurassic and Cretaceous strata--in some of which the shells retain their colours, as well as their brilliant pearly lustre or nacre. At Trouville, in Normandy, in the Kimeridge strata, magnificent _Ammonites_ are found in the clay and marl, all brilliant with the colours of mother-of-pearl. In the Cretaceous beds at Machéroménil, some species of _Ancyloceras_ and _Hamites_ are found still covered with a nacre, displaying brilliant reflections of blue, green, and red, and retaining an admirable lustre. At Glos, near Liseaux, in the Coral Rag, not only the _Ammonites_, but the _Trigoniæ_ and _Aviculæ_ have preserved all their brilliant nacre. Sometimes these remains are much changed, the organic matter having entirely disappeared; it sometimes happens also, though rarely, that they become petrified, that is to say, the external form is preserved, but the original organic elements have wholly disappeared, and have been replaced by foreign mineral substances--generally by silica or by carbonate of lime.

Geology also enables us to draw very important conclusions from certain fossil remains whose true nature was long misunderstood, and which, under the name of _coprolites_, had given rise to much controversial discussion. Coprolites are the petrified excrements of extinct fossil animals. The study of these singular remains has thrown unexpected light on the habits and physiological organisation of some of the great antediluvian animals. Their examination has revealed the scales and teeth of fishes, thus enabling us to determine the kind of food in which the animals of the ancient world indulged: for example, the coprolites of the great marine reptile which bears the name of _Ichthyosaurus_ contain the bones of other animals, together with the remains of the vertebræ, or of the phalanges (paddle-bones) of other Ichthyosauri; showing that this animal habitually fed on the flesh of its own species, as many fishes, especially the more voracious ones, do in our days.

The imprints left upon mud or sand, which time has hardened and transformed into sandstone, furnish to the geologist another series of valuable indications. The reptiles of the ancient world, the turtles in particular, have left upon the sands, which time has transformed into blocks of stone, impressions which evidently represent the exact moulds of the feet of those animals. These impressions have, sometimes, been sufficient for naturalists to determine to what species the animal belonged which thus left its impress on the wet ground. Some of these exhibit tracks to which we shall have occasion to refer; others present traces of the footprints of the great reptile known as the _Labyrinthodon_ or _Cheirotherium_, whose footmarks slightly resemble the impression made by the human hand (Fig. 1). Another well-known impression, which has been left upon the sandstone of Corncockle Moor, in Dumfriesshire, is supposed to be the impress of the foot of some great fossil Turtle.

We may be permitted to offer a short remark on this subject. The historian and antiquary may traverse the battle-fields of the Greeks and Romans, and search in vain for traces of those conquerors, whose armies ravaged the world. Time, which has overthrown the monuments of their victories, has also effaced the marks of their footsteps; and of the many millions of men whose invasions have spread desolation throughout Europe, not even a trace of a footprint is left. Those reptiles, on the other hand, which crawled thousands of ages ago on the surface of our planet when it was still in its infancy, have impressed on the soil indelible proofs of their existence. Hannibal and his legions, the barbarians and their savage hordes, have passed over the land without leaving a material mark of their passage; while the poor turtle, which dragged itself along the silent shores of the primitive seas, has bequeathed to learned posterity the image and impression of a part of its body. These imprints may be perceived as distinctly on the rocks, as the traces left on moist sand or in newly-fallen snow by some animal walking under our own eyes. What grave reflections should be awakened within us at the sight of these blocks of hardened earth, which thus carry back our thoughts to the early ages of the world! and how insignificant seem the discoveries of the archæologist who throws himself into ecstacies before some piece of Greek or Etruscan pottery, when compared with these veritable antiquities of the earth!

The palæontologist (from παλαιος “ancient,” οντος “being,” λογος “discourse”), who occupies himself with the study of animated beings which have lived on the earth, takes careful account also of the sort of moulds left by organised bodies in the fine sediment which has enveloped them after death. Many organic beings have left no trace of their existence in Nature, except their impressions, which we find perfectly preserved in the sandstone and limestone, in marl or clay, and in the coal-measures; and these moulds are sufficient to tell us the kind to which the living animals belonged. We shall, no doubt, astonish our readers when we tell them that there are blocks of sandstone with distinct impressions of drops of rain which had fallen upon sea-shores of the ancient world. The impressions of these rain-drops, made upon the sands, were preserved by desiccation; and these same sands, being transformed by subsequent hardening into solid and coherent sandstones, their impressions have been thus preserved to the present day. Fig. 2 represents impressions of this kind upon the sandstone of Connecticut river in America, which have been reproduced from the block itself by photography. In a depression of the granitic rocks of Massachusetts and Connecticut, the red sandstone occupies an area of a hundred and fifty miles in length from north to south, and from five to ten miles in breadth. “On some shales of the finest texture,” says Sir Charles Lyell, “impressions of rain-drops may be seen, and casts of them in the argillaceous sandstones.” The same impressions occur in the recent red mud of the Bay of Fundy. In addition to these, the undulations left by the passage of the waters of the sea, over the sands of the primitive world, are preserved by the same physical agency. Traces of undulations of this kind have been found in the neighbourhood of Boulogne-sur-Mer, and elsewhere. Similar phenomena occur in a still more striking manner in some sandstone-quarries worked at Chalindrey (Haute-Marne). The strata there present traces of the same kind over a large area, and along with them impressions of the excrements of marine worms. One may almost imagine oneself to be standing on the sea-shore while the tide is ebbing.

CHEMICAL AND NEBULAR HYPOTHESES OF THE GLOBE.

Among the innumerable hypotheses which human ingenuity has framed to explain the phenomena which surround the globe, the two which have found most ready acceptance have been termed respectively the CHEMICAL, and the NEBULAR or mechanical hypothesis. By the first the solid crust is supposed to have contained abundance of potassium, sodium, calcium, magnesium, and other metallic elements. The percolating waters, coming in contact with these substances, produce combinations resulting in the conversion of the metals into their oxides--potash, soda, lime, and magnesia--all of which enter largely into the composition of volcanic rocks. The second hypothesis involves the idea of an original incandescent mass of vapour, succeeded by a great and still existing central fire.

This idea of a great central fire is a very ancient hypothesis: admitted by Descartes, developed by Leibnitz, and advocated by Buffon, it is supposed to account for many phenomena otherwise inexplicable; and it is confirmed by a crowd of facts, and adopted, or at least not opposed, by the leading authorities of the age. Dr. Buckland makes it the basis of his Bridgewater treatise. Herschel, Hind, Murchison, Lyell, Phillips, and other leading English astronomers and geologists give a cautious adhesion to the doctrine. The following are some of the principal arguments adduced in support of the hypothesis, for, in the nature of the proofs it admits of, it can be no more.

When we descend into the interior of a mine, it is found that the temperature rises in an appreciable manner, and that it increases with the depth below the surface.

The high temperature of the waters in Artesian wells when these are very deep, testifies to a great heat of the interior of the earth.

The thermal waters which issue from the earth--of which the temperature sometimes rises to 100° Centigrade and upwards--as, for instance, the Geysers of Iceland--furnish another proof in support of the hypothesis.

Modern volcanoes are said to be a visible demonstration of the existence of central heat. The heated gases, the liquid lava, the flames which escape from their craters, all tend to prove sufficiently that the interior of the globe has a temperature prodigiously elevated as compared with that at its surface.

The disengagement of gases and burning vapours through the accidental fissures in the crust, which accompany earthquakes, still further tends to establish the existence of a great heat in the interior of the globe.

We have already said that the temperature of the globe increases about one degree for every sixty or seventy feet of depth beneath its surface. The correctness of this observation has been verified in a great number of instances--indeed, to the greatest depth to which man has penetrated, and been able to make use of the thermometer. Now, as we know exactly the length of the radius of the terrestrial sphere, it has been calculated from this progression of temperature, supposing it to be regular and uniform, that the centre of the globe ought to have at the present time a mean temperature of 195,000° Centigrade. No matter could preserve its solid state at this excessive temperature; it follows, then, that the centre of the globe, and all parts near the centre, must be in a permanent state of fluidity.

The works of Werner, of Hutton, of Leopold von Buch, of Humboldt, of Cordier, W. Hopkins, Buckland, and some other English philosophers, have reduced this hypothesis to a theory, on which has been based, to a considerable extent, the whole science of modern geology; although, properly speaking, and in the popular acceptation of the term, that science only deals with the solid crust of the earth.

The nebular theory thus embraces the whole solar system, and, by analogy, the universe. It assumes that the SUN was originally a mass of incandescent matter, that vast body being brought into a state of evolution by the action of laws to which the Creator, in His divine wisdom, has subjected all matter. In consequence of its immense expansion and attenuation, the exterior zone of vapour, expanding beyond the sphere of attraction, is supposed to have been thrown off by centrifugal force. This zone of vapour, which may be supposed at one time to have resembled the rings of Saturn, would in time break up into several masses, and these masses coalescing into globes, would (by the greater power of attraction which they would assume as consolidated bodies) revolve round the sun, and, from mechanical considerations, would also revolve with a rotary motion on their own axes.

This doctrine is applied to all the planets, and assumes each to have been in a state of incandescent vapour, with a central incandescent nucleus. As the cooling went on, each of these bodies may be supposed to have thrown off similar masses of vapour, which, by the operation of the same laws, would assume the rotary state, and, as satellites, revolve round the parent planet. Such, in brief, was the grand conception of Laplace; and surely it detracts nothing from our notions of the omnipotence of the Creator that it initiates the creation step by step, and under the laws to which matter is subjected, rather than by the direct fiat of the Almighty. The hypothesis assumes that as the vaporous mass cooled by the radiation of heat into space, the particles of matter would approximate and solidify.

That the figure of the earth is such as a very large mass of matter in a state of fluidity would assume from a state of rotation, seems to be admitted, thus corroborating the speculations of Leibnitz, that the earth is to be looked on as a heated fluid globe, cooled, and still cooling at the surface, by radiation of its superfluous heat into space. Mr. W. Hopkins[7] has put forth some strong but simple reasons in support of a different theory; although he does not attempt to solve the problem, but leaves the reader to form his own conclusions. As far as we have been able to follow his reasoning we gather from it that:--

[7] See _Phil. Transactions_, 1839-40-42; also, _Quarterly Journal of
the Geological Society_, vol. viii., p. 56.

If the earth were a fluid mass cooled by radiation, the cooled parts would, by the laws of circulating fluids, descend towards the centre, and be replaced on the surface by matter at a higher temperature.

The consolidation of such a mass would, therefore, be accompanied by a struggle for superiority between pressure and temperature, both of which would be at their maximum at the centre of the mass.

At the surface, it would be a question of rapidity of cooling, by radiation, as compared with the internal condition--for comparing which relations we are without data; but on the result of which depends whether such a body would most rapidly solidify at the surface by radiation, or at the centre by pressure.

The effect of the first would be solidification at the surface, followed by condensation at the centre through pressure. There would thus be two masses, a spherical fluid nucleus, and a spherical shell or envelope, with a large zone of semi-fluid, pasty matter between, continually changing its temperature as its outer or inner surface became converted to the solid state.

If pressure, on the other hand, gained the victory, the centre would solidify before the circulation of the heated matter had ceased; and the solidifying process would proceed through a large portion of the globe, and even approach the surface before that would become solid. In other words, solidification would proceed from the centre until the diminishing power of pressure was balanced by radiation, when the gradual abstraction of heat would allow the particles to approximate and become solid.

The terrestrial sphere may thus be a solid indurated mass at the centre, with a solid stony crust at the surface, and a shifting viscous, but daily-decreasing, mass between the two; a supposition which the diminished and diminishing frequency and magnitude of volcanic and other eruptive convulsions seem to render not improbable.

It is not to be supposed that amongst the various hypotheses of which the cosmogony of the world has been the object, a literal acceptation of the scriptural account finds no defenders among men of science. “Why,” asks one of these writers,[8] after some scornful remarks upon the geologists and their science--“why an omnipotent Creator should have called into being a gaseous-granite nebulous world, only to have to cool it down again, consisting as it does of an endless variety of substances, should even have been supposed to be originally constituted of the matter of granite alone, for nothing else was provided by the theory, nobody can rationally explain. How the earth’s centre now could be liquid fire with its surface solid and cold and its seas not boiling caldrons, has never been attempted to be accounted for. How educated gentlemen, engaged in scientific investigations, ever came to accept such a monstrously stupid mass of absurdities as deductions of ‘science,’ and put them in comparison with the rational account of the creation given by Moses, is more difficult to understand than even this vague theory itself, which it is impossible to describe.

[8] “Fresh Springs of Truth.” R. Griffin and Co.

“Of the first creation of the chaotic world,” the same writer goes on to say, “or the material elements, before they were shaped into their present forms, we can scarce have the most vague conception. All our experience relates to their existing conditions. But knowing somewhat of the variety of the constituent elements and their distinct properties, by which they manifest their existence to us, we cannot conceive of their creation without presupposing a Divine wisdom, and--if I may say so, with all reverence, and only to suit our human notions--a Divine ingenuity,” and he follows for six days the operations as described by Moses, with a running comment. When light is created, the conception of the work becomes simpler to our minds. Its least manifestation would suffice at once to dispel darkness, and yet how marvellous is the light! In the second day’s work the firmament of heaven is opened; the expanse of the air between the heavens and the earth, dividing the waters above from the waters below, is the work recorded as performed. Not till the third day commence the first geological operations. The waters of the earth are gathered together into seas, and the dry land is made to appear. It is now that we can imagine that the formation of the primary strata commenced, while by some of the internal forces of matter the earth was elevated and stood above the waters.