The World Before the Deluge

by Louis Figuier

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.