﻿1848. ROCKY MOUNTAINS. 175 



the stream escaping through them by successive 

 gaps. Many of the escarpments, when seen from 

 a distance reflecting the rays of the sun, look as 

 bright and white as chalk cliffs ; and but for inform- 

 ation which I have gleaned from voyagers who 

 have crossed them, I should have been in doubt 

 whether they were not formed of that material or 

 of white sand, instead of being hard limestone. 



At this date only a few patches of snow remained 

 in the hollows having a northern exposure ; but in 

 the following year they were entirely covered with 

 snow until late in June, and for some weeks after all 

 the low country had become quite bare. Both the 

 first and second ridges are distinctly stratified at the 

 bend of the river, and seemingly capped with trap. 

 Where they and the succeeding ridges are cut by 

 the river, limestone is the chief rock that is visible; 

 but I have had no opportunity of examining the 

 principal cliffs, and have made but a very cursory 

 inspection of any. The spurs which reach the 

 Mackenzie consist, perhaps, wholly of limestone. 

 Sandstone exists in their vicinity, but I believe it is 

 a newer deposit, belonging to that which forms the 

 floors of the valleys, and rests unconformably on the 

 tilted beds of the ridges. No organic remains were 

 detected in any of the highly inclined beds, but 

 gypsum and chert are of frequent occurrence. 



Traders who have crossed from the Atlantic to 

 the Pacific slopes of the continent say that there 



