118 



THE ICE AGE IN CANADA. 



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slope (amounting, as has 

 been shown, to over four 

 feet per mile) to the first 

 transverse watershed and 

 plateau of the Lignite 

 Tertiary. Such an ice- 

 sheet, moving through- 

 out on broad plains of 

 soft, unconsolidated Cre- 

 taceous and Tertiary 

 rocks, would be expected 

 to mark the surface with 

 broad flutings parallel to 

 its direction, and to ob- 

 literate the transverse 

 watersheds and valleys. 



" If it be supposed that 

 a huge glacier, resting 

 on the Laurentian axis, 

 spread westward across 

 the plains, the physical 

 difficulties are even mare 

 serious. The ice moving 

 southward, after having 

 descended into the Red- 

 River trough, would have 

 had to ascend the eastern 

 escarpment of soft Cre- 

 taceous rocks forming its 

 western side, which in 

 one place rises over 900 

 feet above it. Having 

 gained the second prairie-steppe, it would have had to 



