NO. 17 SMITHSONIAN EXPLORATIONS, IQ1L6 I 
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One of the important incidental results obtained was the discovery 
at Wonder Pass (fig. 3) of the great overthrust 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 to the eastward. 
Fig. 20—QOn the trail to Wonder Pass with a northwest gale to face. The 
horses always turn their backs to the wind when resting. Photograph by 
Walcott, 1916. 
The fault crosses through Wonder Pass and then curves to the north- 
west, southeast of Magog Lake, shown in figure 5, to the great cliff 
forming the northern extension of the Assiniboine massif (fig. 2). 
During the million or more years that the agencies of erosion had 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 point near their origin, high up on the mountains, 
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