Page:Popular Science Monthly Volume 9.djvu/681

Rh alike with reasoning from probability or the investigation of facts. In all the operations of Nature as they unfolded themselves before our eyes God worked by law—by the process of slow development—by means beautifully simple, and involving no violence and no haste, yet irresistible. There was abundant evidence that these causes had been at work for thousands—perhaps millions—of years before the date of the supposed miracle. Beginning from the present age, the time was calculated that each development would require, till the united ages of all amounted to the enormous sum of three hundred millions of years.

Modern English geology holds that all geological changes have been effected by agents now in operation, and that those agents have been working silently at the same rate in all past time; that the great changes of the earth's crust were produced, not by great convulsions and cataclysms of Nature, but by the ordinary agencies of rain, snow, frost, ice, and chemical action. It teaches that the rocky face of our globe has been carved into hill and dale, and ultimately worn down to the sea-level, not only once or twice, but many times over during past ages; that the principal strata of the rocks—hundreds, and even thousands, of feet thick—have been formed on ocean-floor-beds by the slow decay of marine creatures and matter held in solution by the waves; that every part of the earth has been many times submerged, and has again been lifted into the air. This slow rising and sinking of the ground is an axiom of the geological creed. We are told that it is now going on, and that there are large areas of subsidence and of elevation on the surface of the globe. But when we consider the slow rate at which that oscillation is now proceeding, and argue back from the known to the unknown, we are landed in conclusions as to the length of time required for geological changes which the opponents of the theory declare to be absolutely inadmissible.

Sir William Thomson, Prof. Tait, and Mr. Croll, argue the question as one of geological dynamics. They find reason, in recent discoveries of science, to assert that the sun and the earth, from their physical condition, cannot possibly have existed for the enormous length of time supposed. Playfair, the founder of what is called the Uniformitarian school of geology, declares, on the other hand, that in the existing order of things there is no evidence either of a beginning or of an end. "In the planetary motions," he says, "where geometry has carried the eye so far both into the future and the past, we discover no mark either of the commencement or the termination of the present order. The author of Nature has not given laws to the universe, which, like the institutions of men, carry in themselves the elements of their own destruction." This was a bold assertion: it was adopted with very little limitation by Sir Charles Lyell and the later geologists—his disciples and contemporaries. Indeed, if they admitted any limitations at all, they placed the origin of the world so many