20 PROCEEDINGS OF THE AMHERST MEETING 



excellent account of his tour through Japan, northeastern China, Siberia, 

 and Turkestan, which supplied conclusive evidence that during the 

 Glacial period northern and central Asia had no ice-sheets. Glaciers 

 there did not descend to the plains north of the Tian-Shan Mountains, 

 although they are much higher and more massive than the Alps of 

 Europe and are in the same latitude. 



Two other books by Wright, among his many contributions in the 

 fields of religious and theological literature, should be here mentioned 

 for their chapters on Prehistoric Man and the Ice Age, namely, "Studies 

 in Science and Religion," 390 pages, published in 1882, and "Scientific 

 Confirmations of Old Testament History/' 432 pages, in 1906. 



His most noteworthy investigations in glacial geology relate to the 

 unity and continuity of the Ice Age, on which he presented two important 

 papers in the American Journal of Science, for Xovember, 1892, and 

 March, 1894. These dissent from the views that were prominently held 

 by James Geikie and other giacialists, following a theory advocated by 

 Croll, that astronomic conditions bore a large part in the causation of 

 the Ice Age, dividing it into alternating glacial and interglacial epochs. 

 With all the complexity of the drift formations in Europe and in Xorth 

 America, attesting very considerable variations in the extent of ice- 

 sheets, it now seems well nigh certain that the Pleistocene glaciation of 

 both continents was continuous on great central areas, although attended 

 with occasional broad fluctuations of the ice boundaries. 



Closely linked with the foregoing are other questions to which Wright 

 likewise gave constant attention throughout his comprehensive glacial 

 and archyeologic researches. What was the duration of the Glacial period ? 

 When were the ice-sheets finally melted away? To what antiquity do 

 the drift deposits bear testimony of man's presence? 



In accordance with the time ratios of the great geologic eras, as esti- 

 mated by Dana, Walcott, Wallace, and others, Professor Wright's accept- 

 ance of their conclusions, that plant and animal life began probably no 

 longer ago than a hundred million years, must restrict the Ice Age and 

 the existence of mankind to about one or two hundred thousand years. 

 By his latest estimates, however, Wright deemed it improbable that even 

 fifty thousand years have passed since the advent of man and the begin- 

 ning of continental glaciation. From measurements of the rates of 

 erosion and recession of the Saint Anthony Falls and of Xiagara Falls, 

 he coincided with X. H. Winchell and G. K. Gilbert in assigning about 

 seven thousand years as the post-Glacial period, since the melting of the 

 ice border upon Minnesota and the region of the Great Lakes. More 

 recently the careful surveys of Baron De Geer in Sweden have well 



