THE POSITION OF GEOLOGY. 541 



theless the "belief prevails. The result is that, as the last of these 

 astronomical periods was calculated to have commenced two hun- 

 dred 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 unif ormitarian. 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 

 be 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 palaeolithic 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 geologi- 

 cal grounds the need of so great an interval between the end of 

 the Quaternary period and the present time, the uniformitari- 

 ans 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 



