[COLEMAN] THE DRIFT OF ALBERTA 9 



look, but others may be of dissected Laramie more or less veneered with 

 boulder clay. There are narrow valleys without streams between the 

 hills, perhaps preglacial channels from which the flow of water has been 

 diverted by morainic obstructions. 



Similar deposits, partly morainic, partly lacustrine, extend west to 

 McLeod river near the first crossing!, the boulders including both 

 Archaean and Cordilleran rocks. In cut banks along this river Laramie 

 sandstone and shale occur at tlie bottom, and sometimes coarse gravel 

 follows, with boulder clay above, containing both kinds of stones, but 

 the Archaean few in number. 



At the " Big Eddy " of the McLeod, 25 miles west, the banks of 

 Sundance creek show similar sections of Laramie overlain by boulder 

 clay; but here no Archaean boulders were found, only fragments of the 

 local sandstone, shale and lignite, and Eocky Mountains stones. Probably 

 the boulder clay, which has a thickness of 25 to 40 feet, is the equivalent 

 of the lower till of Elbow river. From this point westward no Archaean 

 stones were seen, and the till and morainic ridges contain only local or 

 Cordilleran materials. 



Near the " Leavings " of the Mcl^eod 20 or 30 miles west of the 

 Big Eddy, where the trail crosses the divide to the Athabasca valley, 

 there is a typical Cordilleran terminal moraine with hummocks and 

 kettles and eskers and large blocks of quartzite and limestone 25 miles 

 fiom the Rockies. Boulder clay or morainic forms were not observed 

 farther to the west until the mountains were actually reached. 



Within the mountains along the Athabasca valley there are terminal 

 and lateral moraines on a large scale, the lateral mojaines rising as great 

 irregular terraces on each side, hundreds of feet above the river. These 

 morainic deposits Avere formed by valley glaciers during the retreat of 

 the ice to its present stage. Few of the present shrunken glaciers reach 

 to the main valleys. 



From Firebag river near Lesser Slave Lake to the north of the 

 Athabasca region just described McCounell gives the following section : 



FEET 



Soft sand-tar nodules 50 



Eed boulder clay 20 



Sands 20 



Dark boulder clay 2 



Sands and gravels 15 



♦ 



107 



