DEDUCTIONS FROM RELATIONS OF THE DRIFT 549 



unquestionably in situ, not far above the present streams. Hence, even if 

 we conclude that erosion of the Blackfoot peneplain had not progressed 

 nearly so far as now in the Browning quadrangle and its immediate en- 

 virons, we must concede that there is evidence 40 to 50 miles north of 

 the boundary that the valleys of Oldman and Belly rivers had been cut to 

 nearly as low levels as now before the pre-Wisconsin drift was deposited, 

 and the intervening uplands must have been correspondingly lowered. 



It may be well to present in some detail the results of our observations 

 on the upper and lower boulder clays of the Keewatin ice-sheet. 



In the course of our reconnaissance trip in southern Alberta a day was 

 spent at Lethbridge and an examination was made of the series of drift 

 deposits described by Dr. G. M. Dawson. 9 In the time spent, however, 

 there was opportunity for study of only a small part of the fine exposures 

 in this vicinity. 



For some distance both north and south of the railway bridge at this 

 place the drift deposits are well exposed in the bluffs forming the sides 

 of the valleys. Belly Eiver Valley at this place is about 300 feet in 

 depth, a steep-sided trench cut in the undulating plain. Going down 

 from the railway station into the valley south of the railway bridge to 

 the vicinity of the municipal coal mine, filter beds, and electric power- 

 house, the following series of deposits was observed in the east bluff : 



Pleistocene Deposits on Belly River at Lethbridge, Alberta 



D. Buff, loose-textured to moderately compact, clayey till of Kee- Feet 

 watin Glacier (Wisconsin stage) containing plentiful Lauren- 

 tian pebbles and Paleozoic ( ?) limestone pebbles, beneatb upper 

 grassed slope 150± 



C. Fine, gray, compact, cemented sand or silt ( interglacial ?), with, 

 in places, some intercalated thin layers of brown to black 

 lignitic material; contorted in part in places; clay-iron 

 nodules in places at top of bare shoulders of the bluff 10± 



B. Dense, compact, dark gray till of Keewatin Glacier (pre-Wis- 

 cousin stage), pebbles mostly from the Rocky Mountains; 

 Laurentian pebbles plentiful but less abundant than in upper 

 till ; forms bold salient of the bluff 40 to 50 



A. Stratified gravel ("Saskatchewan;' interglacial or preglacial), 

 composed mostly of 4 to 6 inch, well-rounded pebbles of 



quartzites from the Rocky Mountains 10 to 12 



Cretaceous shale and coal 



9 G. M. Dawson: Report on the region in the vicinity of the Bow and Belly rivers. 

 Northwest Territory. Geological Survey of Canada, 1882-1884, 1884, pp. 1890-1520, and 

 plate op. p. 140c. 



G. M. Dawson (with collaboration of B. G. McConnell) : Glacial deposits of south 

 western Alberta in the vicinity of the Rocky Mountains, Boll. Geol. Boc, Am., vol. 7, 

 1895, pp. 39-41. 



