72 GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 



its ndve it is three miles in length and for its upper two-thirds nearly one mile 

 in breadth. In rounding the rock embossment noted it narrows to a half 

 mile and then tapers regularly to a blunt nose. The mean elevation of the 

 n6v6, according to Wheeler, is 8,400 feet, and the nose descends to an altitude 

 of 5,670 feet. By noting the temperature of boiling water, Habel determined 

 this elevation at 5,680 feet. The nose of the Yoho is thus 330 feet lower than 

 that of the Victoria, and 730 feet lower than the Wenkchemna, in spite of the 

 lack of debris covering and the southerly exposure. This is due, without doubt, 

 to the greater precipitation and the greater size of the collecting area, by which 

 a much larger body of ice is amassed. The mean average slope from the n6v6 

 to the nose is about 900 feet to the mile; the main part of the descent, however, 

 is in the lower half. The general inclination of the ice about the front is 20° to 

 25°. Upon the western side the glacier presses more or less firmly against the 

 valley wall, except for a short distance, where the ice is steep and not to be ascended 

 without cutting steps. By crossing the drainage stream, which is not a simple 

 proposition unless one is mounted, one may easily ascend the glacier without 

 the cutting of steps, the ice slope being very gentle. Skirting the crevasses and 

 crossing back to the west side of the glacier, the n6v6 may be easUy and safely 

 reached. Since its discovery by Habel , the glacier has maintained a great archway 

 of ice at its lower extremity, which spans 250 feet of space, and is estimated to be 

 70 feet high, from ^\•hich escapes the drainage. Owing probably to its southern ex- 

 posure there is formed a cavern beneath the arch, as seen in plate xxvii, figure 4, 

 extending back into the ice 100 to 200 feet, but not forming a subglacial tunnel. 

 Toward the close of the summer season, the arch has become so weakened by 

 melting and the formation of a transverse crevasse (plate xxvii, figure 3) that 

 the entire structure collapses and lies a heap of azure ruins. The blocks of ice 

 are melted down to a size that the stream can push, roll, or float, some head being 

 obtained for the stream by the damming action of the ice debris. Finally it is 

 all removed and the making of a new archway is started. 



The actual nose of the glacier lies to the east of the archway and rests upon 

 limestone bedrock, with only a sprinkling of ground-morainic material. Upon 

 either side, and for some distance beyond the nose of the glacier, there is bed- 

 rock exposed, which has been smoothed in places by previous ice action and 

 in other places roughened by plucking. Upon the western margin of the drain- 

 age brook there are shale strata upon edge which have been thus roughened. 

 Excessively thin laminae alternate of an intense red and yeUow color. There are 

 no reliable data for estimating the thickness of the ice, but it seems to be consid- 

 erable. In the case of the Victoria and Wenkchemna glaciers the most conspicu- 

 ous geological work being done is transportation, in the case of the Yoho we 

 have very plainly a great engine of erosion. 



2. Nourishment. 



The collecting area of the Yoho is triangular in outline and includes the region 

 between Mt. Collie (10,315 feet), Mt. Baker (10,441 feet), and Mt. Gordon (10336 



