82 GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 



mile. The greater part of this drop is in the upper half; the glacier descending 

 from the rim of the basin in a steep cascade, by which the ice is shattered and 

 its original structure destroyed (plate xxxii, figure 2). In its short length the 

 glacier receives no tributaries, but instead has a series of short distributary noses 

 perched high up along the eastern line of cliffs leading to Perley Rock (plate xxx) , 

 with elevations ranging from 6 ,45 o feet to 7 ,000 feet. No data exist for estimates 

 upon the thickness of the glacier, but the greatest thickness of ice probably 

 occurs below the crest of the cascade and may amount to several hundred feet. 



The marginal ice is very steep upon the eastern side and for a quarter of a 

 mile back from the nose upon the western side, so that it can not be easily 

 ascended. Toward the nose the general inclination is about 30° to 35°, dimin- 

 ishing to 20° and less, so that one may mount the glacier from the nose for a short 

 distance. The nev6 may be reached by a rather rough climb, either around to 

 the east by Perley Rock, or by ascending to the depression between the glacier 

 and the steep left lateral moraine, keeping a sharp lookout at first for rolling 

 rock from the eastern face of the moraine. About the main nose, upon the 

 eastern side, there occur a number of minor noses, shown in plate xxx and plate 

 XXXII, figure 2, and also a sharply defined, trough-like depression in the surface 

 of the ice, from 200 to 300 feet across and tapering up stream for a considera- 

 ble distance. This depression appears in all the photographs taken since 1887 

 (plates xxxvi, xxxvii, figure 2), since which date about 400 feet of the floor 

 immediately beneath it have been uncovered without disclosing any cause for 

 the depression. In plate xxxii, figure 2, it appears to be continued up the glacier 

 to the cascade and may have its origin there in some obstruction of the bed by 

 which the ice is diverted to either side and left thinner in the lee. Just to the 

 left of the nose there has been uncovered, since 1898, a mass of bedrock for a 

 distance of 400 feet, its more rapid radiation of heat accelerating the melting of 

 the ice resting upon it. The rock consists of a brownish, schistose conglomerate, 

 furnishing an interesting display of glacial features to be described in another 

 section of the chapter (page 95 J. This is the only bedrock observed in the 

 floor of the valley from the glacier to the station. 



2. Nourishment. 



Meteorological data at the station of Glacier House are, unfortunately, very 

 meager. The average precipitation for the five years available amounts to 56.68 

 inches, of which 43.7 inches (36 feet and 5 inches), or about 77 per cent, of the 

 whole, fell as snow.' Over the nevd region practically this entire amount 

 would be available for glacier formation and, as snow, would represent about 

 47 feet. The retangular snow-field extending from Mt. Sir Donald to Mts. McCoun 

 and Fox is about five miles long, by two miles broad, and hence contains about 

 ten square miles of collecting area (plate xxxiii). Of this area about two-thirds, 

 or six to seven square miles, drains northward and feeds the lUecilliwaet, 

 while the remainder moves southward and nourishes the Geikie Glacier, which 



' The Selkirk Range, A. O. Wheeler, vol. i, p. 414. 



