28 REPORT— 1886. 



uuasaally cold winters the great precipitation of snow takes place south of 

 Canada, leaving the north comparative ly bare, while aa 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 raost potent cause of a glacial age. 



I have long maintained these conclusions on general geographical 

 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 gi'eat 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 warmer 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 extension 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 * that in North America a continental glacier extended in tem- 

 perate latitudes from sea to sea, or at least from the Atlantic to the 

 Bocky Mountains, and that this glacier must, in many places, have 

 exceeded a mile in thickness. The reasons above stated appear, however, 

 sufficient to compel us to seek for some other explanation of the observed 

 facts, however difficult this may at first sight appear. With a depression 

 such as we know to have existed, admitting the Arctic currents along the 

 St. Lawrence Valley, through gaps in the Laurentian watershed, and 

 down the great plains between the Laurentian areas and the Rocky 

 Mountains, we can easily understand the covering of the hills of Eastern 

 Canada and New England with ice and snow, and a similar covering of 

 the mountains of the west coast. The sea also in this case might be 

 ice-laden and boulder-bearing as far south as 40", while there might still be 

 low islands far to the north on which vegetation and animals continued 

 to exist. We should thus have the conditions necessary to explain all the 

 anomalies of the glacial deposits. Even the glaciation of high mountains 

 south of the St. Lawrence Valley would then become explicable by the 

 grounding of floe-ice on the tops of these mountains when reefs in the sea. 

 In like manner we can understand how on the isolated trappean hill of 

 Beloeil, in the St. Lawrence Valley, Laurentian boulders far removed from 

 their native seats to the north are perched at a height of about 1,200 feet 

 on a narrow peak whero no glacier could possibly have left them. The 

 so-called moraine, traceable from the great Missouri Cotean in the west, to 

 the coasts of New Jersey, would thus become the mark of the western and 



' Kcport of Mr. Carvill Lewis in Penmylvania Geological Swrvey, 1884; also 

 Dana's Manual. 



