PHYSICAL FEATURES OF THE REGION. 



33 



and infolds of Cretaceous rocks occur in this part of the mountains, while 

 at least one isolated area of Paleozoic rocks is found to the east of the 

 main margin of the range. Both the mountains and the adjacent foot- 

 hills have been subjected to similar parallel folding and disturbance at 

 the same post-Cretaceous orogenic period.* 



Scale 



Miles. 



Figure i. — Southwestern Part of the District of Alberta. 



The foothill belt varies in width from 10 or 12 miles in its southern 

 part to about 20 miles at the north, in the vicinity of Bow river. Funda- 

 mentally, the foothills represent a bordering zone of folded and con- 

 torted Cretaceous rocks, reduced by denudation to series of more or less 

 nearly parallel ridges and valleys. The rivers and larger streams from 

 the mountains generally cut across nearly at right angles in wide and 

 relatively low transverse valleys, while the higher ridges and hills occa- 

 sionally surpass 5,000 feet in elevation. 



* For some notes on this and on the Pliocene history of the region, see Am. Jour. Sei., June, 1895, 

 p. 463. 



