﻿GLACIAL STUDIES IX CANADIAN ROCKIES 



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from the glacier itself, from its distributar} and the drainage from 

 the adjoining valleys, fts water is somewhat turbid, but nol so much 

 so as that which issues from the Victoria, and its temperature in 

 mid-August averaged 34.25 I'"., varying a degree in either direction. 

 During the summer a crevasse opens across the arch, permitting the 

 ice to incline forward until it collapses finally and lies a heap of 

 azure ruins until removed by water and sun. 



4. Ice Retreat. — The nose of the glacier lies just east of the arch- 

 wax- and rests upon bedrock. In August, [901, independent mark- 

 were established by Miss Vaux and II. W. DuBois, from the former 

 of which it was found that the ice here has retreated 1 1 1 ft. in three 

 years, or at an average rate of 37 ft. a year. This measurement was 

 made to the "lacier itself and not to the detached block which has 

 been the nose. Measured to this block the distance was 92.] ft.. 

 giving an average of nearly 31 ft. a year, with a retreat of 23 ft. for 

 the year 1003-4- The glacier seems to have been steadily retreating 

 for a number of years, so far as may he judged from the weak de- 

 velopment of terminal moraine. Tt should he noted, however, that 

 even a considerable halt could produce only an inconsiderable moraine 

 because of the small amount of debris carried. 



Between the nose of the glacier and its distributary, upon the 

 eastern valley slope, there occurs an interesting ridge of tree trunks, 

 resting upon a slight morainic ridge and parallel with the present 

 margin of the ice. It lies about 260 ft. up the slope and represents 

 the work of an avalanche against the side of the ice when it occupied 

 this position. The oldest living trees found in the path of tins 

 avalanche gave 47 rings of growth. This avalanche probably oc- 

 curred between 1850 and i860, since which time the side of the 

 glacier has been retreating down the slope at the average rate of 

 between five and six feet a year. 



5. Modified Moraine. — Some 800 ft. down from the present nose 

 of the Wapta there occurs a peculiar group of low knolls and cres- 

 centic ridges, lying to the east of the drainage stream, and con- 

 nected with the weak, left lateral by faint ridges. Six concentric 

 series may he made out, the ridges having their convexities directed 

 down stream (fig. 85 ). diminishing in height and distinctness toward 

 the glacier. These ridges vary in height from one to 12 ft. and the 

 longest is in the form of a semi-circumference with a radius of 20 

 ft. They all possess the smoothed, rounded outlines of drumlins, 

 lmt lack their profile and arrangement. They consist of a core of 

 ground morainic material with a thin dressing of sand and gravel. 

 They have apparently been produced about the nose of the glacier, 



