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Page:Popular Science Monthly Volume 44.djvu/555

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541
THE POSITION OF GEOLOGY.

theless the belief prevails. The result is that, as the last of these astronomical periods was calculated to have commenced two hundred and fifty thousand years and to have ended eighty thousand years ago, these numbers have become stereotyped as those of the beginning and the end of the Glacial period.

The able author of this hypothesis, in his attempt to reconcile geological and astronomical time, built his geological argument upon the rate of erosion of rivers at the present time, as held by the uniformitarian. Nevertheless, an observation of his own, that must be indorsed by all geologists, whatsoever their creed, shows the fallacy of adopting the rates of the present day as measures for the past, for he remarks: "If the rate of denudation he at present so great, what must it have been during the Glacial period? It must have been something enormous." Very true, yet the argument proceeds as before. With the admission here made, how is it possible to adopt a scale admitted by its advocate to be subject to such variation? Its retention only serves to divert the real issue and stay inquiry.

Another objection to this chronology is that it fixes the date of the disappearance of pal├Žolithic man and the Quaternary fauna at a distance of eighty thousand years from our own times. Of these eighty thousand years, we can account for ten or twelve thousand during which neolithic and recent man has been in occupation of the land; but this leaves some seventy thousand years unaccounted for. Unable satisfactorily to show on geological grounds the need of so great an interval between the end of the Quaternary period and the present time, the uniformitarians find a more colorable defense on biological grounds. They point, in a manner we do not quite understand, to the circumstance that with the close of the Post-glacial period a number of the animals then living disappear from the scene, and contend that for the dying-out of so many species long ages must have been required. Had they been able to show the working of evolution in the coming in of new species by descent from the extinct species, or of change in the contemporary species still living, their argument could not be gainsaid. But there is no question of evolution. The mammoth and woolly rhinoceros disappeared for good; the reindeer, musk ox, and glutton were driven to northern latitudes, and there still survive unchanged; while the horse, ox, red deer, wolf, fox, badger, hare, and others remain on with us without variation of species. The extraordinary change of climate which then took place is quite sufficient to account for such changes as these, which are chiefly of those of faunal distribution, having been effected in a measurable length of time, instead of needing the vastly long period mentioned. This length of time could hardly have failed to involve more extensive changes