NO. r 



SMITHSONIAN KX I'LOKATIOX: 



1 1 6 



One of the important incidental results ohtained was the discovery 

 at Wonder Pass (fit;'. 3) of the threat overthrusi fault by which the 

 basal Cambrian rocks forming- the mountains on the west (right) 

 side of the Pass have been thrust eastward over upon the limestones 

 of the Devonian, shown in the slope on the east (left) side of the 

 Pass. The thrust along this fault has carried the rocks forming the 

 main range of the Rockies in this area several miles (o the eastward. 



I'lG. 20. — On the trail to VVoiuler Pass with a nurthvvt;>l. gait* tu lace. 1 he 

 horses always turn their backs to the wind when resting. Photograph by 

 Walcott, 1916. 



The fault crosses through Wonder Pass and then curves lo the uorlh- 

 west, southeast of Magog Lake, shown in figure 5, to the great chff 

 forming the northern extension of the Assiniboine massif (fig. 2). 

 During the million or more years that the agencies of erosit)n liad been 

 wearing away the great mass of rocks above the fault, mountain 

 peaks, canyons, and ridges have been carved and polished by frost, 

 snow, and the grinding force of huge glaciers. The glaciers have now 

 retreated to a ])oint near their origin, high u]) on the mountains, 



