540 THE POPULAR SCIENCE MONTHLY. 



siderations, have, it seems to us, placed the later Quaternary 

 times at far too great a distance from the present. In the same 

 way, the rate at which the elevation of the land took place hav- 

 ing been estimated on the mean of two and a half feet in a 

 century, would, if that scale were accepted, manifestly push back 

 to a very remote distance even later geological changes. 



The importance of determining these points more accurately 

 became more evident when it was discovered that man existed 

 with the extinct mammalia ; and therefore upon the solution of 

 the time-rate problem depended the determination of the an- 

 tiquity of man upon the earth. Various have been the attempts 

 since made ; but, as they have almost all been made upon meas- 

 urements based on the above-named scales, they necessarily 

 involved a very free use of time. For long, geologists had held 

 to the belief, prevailing half a century ago, that man could not 

 have existed on the earth for more than five to six thousand years. 

 "When evidence was given, and at last accepted, to prove a higher 

 antiquity, the uniformitarians- were placed in the difficulty of 

 proving too little or too much. If they adopted a short chro- 

 nology, it would clash with the corner stone of their belief as to 

 the age of the Quaternary deposits ; if, on the other hand, they 

 retained their belief in the great length of time they held to be 

 necessary for the formation of the post or later glacial deposits, 

 they would have to assign to man an antiquity which would 

 clash sorely not only with their own previous belief, but also 

 with that held on various grounds by other geologists and an- 

 thropologists. 



The fetich of uniformity prevailed, the uniformitarians made 

 volte-face to their former contention, and hesitated not to claim 

 for man an antiquity going on for a million years. One old 

 friend of ours, in a public lecture, even put in a claim for two 

 millions, heedless of the cries of his unprepared audience to re- 

 mind him of the rights of Adam. At a loss to prove their case 

 by independent geological evidence, they found an unexpected 

 ally in a novel and ingenious astronomical hypothesis, which 

 apart from its connection with geology we will not contest. The 

 object of the hypothesis was to show that there had been cycles, 

 in which at times the position of the earth in its orbit was such 

 as would cause a great lowering of the terrestrial temperature 

 and give rise to recurring glacial periods. Here were offered 

 the definite measures that geology failed to furnish, and which 

 tallied too well with the time needed by the uniformitarians to 

 be neglected. It was therefore eagerly adopted, and has since 

 been prominent in geological literature. That the hypothesis, 

 however, is not in accordance with the facts of geology has been 

 abundantly shown both in America and in this country ; never- 



