GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 75 



merit. In the valley occupied by the distributary described, and from 600 to 

 700 feet down from its nose, there begins a second lateral which curves around 

 upon the debris-covered ice and continues for two miles along the shoulder of 

 Mt. Gordon. This portion of Gordon has an elevation of 9,510 feet, but its 

 cliffs do not overhang and contribute only a moderate amount of material to the 

 moraine. A considerable portion of it consists of ground moraine which may 

 be traced to the glacier from Mt. Gordon. This sustains the same relation to the 

 Yoho as does the Collie Glacier upon the opposite side of the valley. Up to 

 heights of 30 to 40 feet patches of morainic material can be seen upon the valley 

 wall, left there when the surface of the glacier stood at a higher level. The rocks 

 in the moraine are largely limestone, light and dark, yellow and mottled; some 

 pieces being oolitic. 



An older lateral moraine, upon the eastern side of the valley slope, may be 

 traced for some 2,000 feet up the valley from the nose. The ridge is some 200 to 

 300 feet from the margin of the ice, is but three to four feet high and inconspicu- 

 ous, but it has heaped promiscuously over it a mass of broken tree trunks very 

 evidently brought down by an avalanche and heaped against the side of the ice 

 when it stood here. The distance from the margin of the ice to the ridge, at one 

 point, was found to be 260 feet, along the slope. The wood is somewhat decayed 

 and gives some appearance of age. A photograph was taken when the trunks 

 were covered with a light fall of snow, which had melted from the surrounding 

 rock, rendering them much more conspicuous than they would otherwise be 

 with their dark surroundings. Growing in the path of the avalanche trees 

 were found, the largest of which gave 25, 28, and 47 rings respectively. It is 

 likely that the avalanche occurred between 1850 and 1860, since which time 

 the glacier has been retreating down the slope at the average rate of 5 to 6 feet 

 per annum. 



With so little rock debris carried upon and within the glacier it would require 

 a very prolonged halt of the front in order to build up a terminal moraine of any 

 considerable proportions. About 200 feet from the present nose, at the end of 

 the bedrock upon which it rests, there swings in from the side a weakly developed 

 double ridge, low and inconspicuous. It may be the correlative of the lateral 

 moraine above noted, carrying the avalanched timber, or it may mark a still 

 more recent halt in the general retreat. Within recent time the glacier has 

 deposited very little ground moraine, the conditions not being favorable for its 

 lodgment. The lowermost stratum shows upon the western side of the drainage 

 stream, beneath the archway, and is seen to be charged with debris. Much of 

 this is delivered to the stream and swept away by the swift current, the remainder 

 being spread thinly over the valley floor. 



5. CREVASSES. 



Opposite the head of the rock embossment described, the glacier and its dis- 

 tributary plunge over a steep step in their beds, of which the embossment itself 

 is probably a portion which the glacier was unable to reduce to the general level 



