8o GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 



slope, if not over the crest of the peak. It is well to note that this was done 

 with a relatively thin sheet of ice, while in the valley bed, with some 3,000 feet 

 additional of ice thickness, the result, under equally favorable position of the 

 strata, would have been correspondingly greater. It seems very probable that 

 the peculiar form of the peak Trolltinder (9,414 feet), just south of Balfour 

 (plate xxvni, figure 2), is due to similar plucking action. 



c. Yoho Valley. There is abundant evidence that the entire valley, from 

 the Kicking Horse at Field, was occupied by an immense ice stream, seventeen 

 miles in length, which served as a tributary to the ancient Kicking Horse Glacier, 

 of Pleistocene time. It, in turn, received short tributaries from the adjoining 

 valleys and mountain slopes. The valley was filled with ice to a depth of 1,500 

 to 3,000 feet above the valley floor, by which the lower portion was transformed 

 into the characteristic U-shape, seen best from below. When viewed from a height 

 as in plate xx vin, figure 2, the more flaring walls of the upper portion become the 

 more conspicuous. The valley seems to have had the same general history as 

 that given for the Lake Louise district, page 61. Being a longitudinal valley 

 of the Rocky System, it was originally a trough between mountain folds, or a 

 great crevasse, which collecting the drainage of the region was cut into a V- 

 shaped valley by the joint action of running water and the weather. With the 

 coming of the glaciers, the valley was occupied by ice and the lower one-third 

 to one-half deepened and broadened, while the upper portion, as high as the ice 

 could operate, was simply smoothed and subdued. Spurs were cut off and 

 faces exposed to the action of the ice were grooved and fluted, polished or 

 scratched. 



A series of typical hanging -valleys occur along the Yoho beginning with that 

 of the distributary, the floor of which is not yet uncovered. This ice stream has 

 not been able to lower its bed as rapidly as has the main Yoho, and when melted 

 back to the head of the rock embossment there will be exposed a side floor at a 

 higher level than the main floor. However hanging- valleys, in general, may 

 arise, this one seems certainly due to the differential effect of the two streams upon 

 their respective beds. To the right of the distributary there extends a hanging- 

 valley to the northeastward between Mts. Gordon and Balfour, still occupied 

 by two glaciers, which appear to have built conjointly a double frontal moraine 

 (plate xxix, figure 2) . This valley has a double floor, of which time did not permit 

 an examination. From the photographs taken there appears to be a lake, occupy- 

 ing a rock-basin upon the lower level. About 3^ miles down from the nose of the 

 Yoho the Twin Falls drop into the valley from the floor of a hanging-valley 

 coming in from the west. The falls are 310 feet in height, but their crest (6,500 

 feet) is 1,050 feet above the floor of the main valley opposite. Five miles down 

 from the glacier are seen the Takakkaw Falls, in the center of plate xxvm, figure 

 2 , the crest of which is i , 200 feet above the valley floor. The valley floor from the 

 glacier to these falls descends about 770 feet, or at the average rate of 154 feet 

 to the mile. These figures, based upon data supplied by Wheeler, indicate that 

 the main valley has been lowered from 1,000 to 1,200 feet more than the tributary 



