Presidential Address. 2 I 75 



summer verdure of Grinnel-land, which, in the immediate 

 vicinity of North Greenland, presents very different condi- 

 tions as to glaciation and climate. 1 If the plains were sub- 

 merged, and the Arctic currents allowed free access to the 

 interior of the continent of America, it is conceivable that 

 the mountainous regions remaining out of water would be 

 covered with snow and ice, and there is the best evidence 

 that this actually occurred in the Glacial period ; but with 

 the plains out of water, this would be impossible. We see 

 evidence of this at the present day in the fact that in unu- 

 sually cold winters the great precipitation of snow takes 

 place south of Canada, leaving the north comparatively bare, 

 while as the temperature becomes milder, the area of snow- 

 deposit moves farther to the north. Thus a greater extension 

 of the Atlantic, and especially of its cold, ice-laden Arctic 

 currents, becomes the most potent cause of a glacial age. 



I have long maintained these conclusions on general geo- 

 graphical grounds, as well as on the evidence afforded by the 

 Pleistocene deposits of Canada; and in an address, the theme 

 of which is the ocean, I may be excused for continuing to 

 regard the supposed terminal moraines of great continental 

 glaciers as nothing but the southern limit of the ice-drift of 

 a period of submergence. In such a period, the southern 

 margin of an ice-laden sea, where its floe-ice and bergs 

 grounded, or where its ice was rapidly melted by water, and 

 where, consequently, its burden of boulders and other debris 

 was deposited, would necessarily present the aspect of a 

 moraine, which by the long continuance of such conditions, 

 might assume gigantic dimensions. Let it be observed, 

 however, that I fully admit the evidence of the great exten- 

 sion of local glaciers in the Pleistocene age, and especially 

 in the times of partial submergence of the land. 



I am quite aware that it has been held by many able 

 American geologists 1 that in North America, a continental 

 glacier extended in temperate latitudes from sea to sea, or 

 at least from the Atlantic to the Eocky Mountains, and that 



1 Report of Mr. Carvill Lewis, in Pennsylvania Geological Survey 

 1884 ; also Dana's Manual, 



