Canadian Rocky Mountains. 289 



quartzites, and may prove, in the western part of the range, 

 to pass down into Silurian or Cambro-Silurian. Triassic or 

 Permo-Triassic red sandstones appear in some places near 

 the forty-ninth parallel. 



In the earliest Cretaceous times, this portion of the Eocky 

 Mountains appears to have been an area of subsidence in 

 which several thousand feet of shales and sandstones were 

 deposited. These contain a characteristic early Cretaceous 

 or Cretaceo-Jurassic flora and have been named the Kootanie 

 Series. The conditions at this time appear to have been 

 different from those obtaining in the Western States, as the 

 equivalents of these oldest Cretaceous beds have not there 

 been detected. Deposition, accompanied by some evidence of 

 denudation of the older rocks, continued, over the greater 

 part of the area, till the close of the Cretaceous, and the 

 still later beds of the Laramie are yet found in a few places 

 in the mountains. Throughout the whole of these periods, 

 no evidence of great disturbance is found, and the region 

 was not a mountainous one. For the next ensuing period, 

 however, no representative strata are met with, and it is to 

 this time, coeval with the earliest Tertiary, that the pro- 

 found changes producing this mountain system are due. 

 The beds were then thrown into a series of parallel folds 

 trending north-north-west by south-south-east, and these, 

 by a continuance of pressure from the west, were closely 

 pressed together, and in many cases — particularly on the 

 eastern side — completely overturned eastward. The sub- 

 sequent action of denudation on the higher and more ample 

 folds of this corrugated area has almost completely remov- 

 ed from them the whole of the Mesozoic rocks, while along 

 the eastern margin of the disturbed region, in which the 

 folding has been in many places scarcely less severe, the 

 newer rocks still form the actual surface. This eastern 

 belt, with an average width of about fifty miles, forms 

 the foot-hills ; while the western portion, with a width of 

 about fifty miles, constitutes the mountains proper, the 

 rugged character of which is almost as much due to the 

 nature of the older rocks there brought to the surface as to 

 its superior elevation. 



