266 W. UPHAM — GLACIAL LAKES IN CANADA. 



the earlier drift, belouging to the first Glacial epoch, and the later drift, be- 

 longing to the much later second Glacial epoch, have been delineated by 

 President Chamberlin, combining the results obtained by the explorations 

 of many observers during the past twenty-five years.* The southern margin 

 of the drift is shown to lie wholly within the United States, excepting that 

 it is indented at the eastern foot of the Rocky Mountain range by an angle 

 which barely touches the 49th parallel. Dr. Dawson's more recent map of 

 the extent of the drift in the western part of Canada, however, places the 

 apex of this angle south of the international boundary, along which he has 

 had exceptional opportunity for examination. f But the limit of the ice-sheet 

 of the second Glacial epoch, to which our glacial lakes are referred, is found 

 north of this boundary from the 104th to the 114th meridian, that is, across 

 southern Assiniboia and Alberta, from the Coteau du Missouri to the Rocky 

 Mountains. The abundance of lakelets held in hollows of the drift and the 

 small amount of change in the drift contour since the departure of the ice- 

 sheet indicate that the latest glaciation of these provinces reached south to 

 the Wood mountain and Cypress hills and to Lake Pakowki and the upper 

 portion of Milk river. 



Including this Canadian part of the southern limit of the second ice-sheet, 

 its course may be briefly noted as follows: From Nantucket, Martha's Vine- 

 yard, Block island, and Long island, it runs west-northwestward across 

 northern New Jersey and northeastern Pennsylvania, to an angle near 

 Salamanca, N. Y., about fifty miles south of Buffalo and the eastern end of 

 Lake Erie ; thence it passes southwestward into southern Ohio ; thence west- 

 northwestward and northward in numerous loops through Indiana, north- 

 eastern Illinois, and Wisconsin, to an angle less than seventy-five miles 

 southeast of the western end of Lake Superior ; thence southward to Des 

 Moines, Iowa ; thence north-northwestward to the head of the Coteau des 

 Prairies ; again southward to the Missouri river and northeastern edge of 

 Nebraska ; thence northwestward, very irregularly lobate, through South 

 Dakota and North Dakota, to Wood mountain in the southern edge of 

 Assiniboia ; thence westward by the Cypress hills to the Rocky Mountains 

 on the international boundary ; and thence, in lobes determined by the 

 mountainous character of the country, across northwestern Montana, the 

 narrow northern extremity of Idaho, and the northeastern edge and the cen- 

 tral and western parts of Washington, to the Pacific coast in the latitude of 

 48°, Puget sound and the Strait of Juan de Fuca being wholly inside the 

 glaciated area. 



Along the shores of British Columbia and southern Alaska the ice-sheet 

 pushed through gaps of the Coast range and terminated in the sea from the 



*U. S. Geological Survey, Seventh Annual Report, Plate VIIL 

 t Trans. Royal Society of Canada, vol. VIJI, sec. iv, 1890, Plate II. 



