Part 1 (1/2)

The World Before the Deluge.

by Louis Figuier.

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 pa.s.sed. 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 Rhaetic (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 sh.e.l.ls, 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 pa.s.sed 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 sh.o.r.e, wearing away the coast with endless repet.i.tions 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 ma.s.ses 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.