4 ROYAL SOCIETY OF CANADA 



transport the boulders. Tyrrell and others belie\G that most of the 

 boulder clay of the plains was laid down by the Keewatin ice sheet, but 

 that floating ice played its part along the margin of the Kocky Moun 

 tains. 



Even the railway geologist crossing the continent by the Canadian 

 Pacific has his interest roused by the blocks of granite, gneiss and green- 

 stone of eastern origin shown in the boulder clay of cattings or on 

 morainic ridges or scattered in many places over the surface of the 

 prairie. These may be seen from point to point all the way to Calgary, 

 only 40 miles from the nearest range of the Rockies. Beyond this one 

 sees only quartzites and blue liiaestones from the mountains or local Lara- 

 mie sandstone originating in the foothills. There seems to be a transition 

 between the two classes of stones in the boulder clay, the number of 

 granites and gneisses diminishing while Rocky Mountain quartzites, 

 generally smaller and more rounded, become intermixed in larger num- 

 bers till at Calgary the eastern rocks cease. 



These facts were of course, pointed out long ago by Dawson, Mc- 

 Connell and Tyrrell; and are recalled here merely by way of stating a 

 problem calling for solution. 



These three geologists have also noted in various reports and papers 

 the fact that in river cuttings frequently more than one sheet of boulder 

 clay may be observed, with iiiterglacial beds, often containing lignite, 

 between. At the base of the drift deposits there is often a sheet of 

 coarse quartzite gravel named by McConnell the Saskatchewan gravels, 

 and believed to be the extension of the Albertan boulder clay, transported 

 eastwards by glacial rivers. 



The whole question is discussed by Dr. Dawson in his paper on 

 " Glacial Deposits of Southwestern Alberta in the Vicinity of the Rocky 

 ^Mountains ;" ^ and details may be found in various reports of the 

 Geological Survey of Canada.^ 



As Calgary is apparently the western boundary of the Archaean 

 drift, it was decided to study the sections along its river channels to 

 find a solution of the problems presented. 



Sectioîsts on Elboav River. 



Just above the railway bridge over Elbow river cut banks expose 

 only sandstone capped with gravel; but a short distance up stream about 



1 Bull. Geol. Soc. Am., vol. 7, pp. 81-66, 1895. 



2 Boundary Commission, Dawson, 1875 ; G.S.C., 1882-4 Part C, Dawson, 1880 

 Part E and 1886 Part E, Tyrrell ; 1889-9 Part D, and 1990-1 Part D, McConnell. 

 See also Tyrrell in Bull. Geol. Soc. Am., vol. 1, pp. 395-410. 



