$8 GLACIERS OP THE CANADIAN ROCKIES AND SELKIRKS. 



t 



though a satisfactory explanation has not been found. Observations were begun 

 upon the Victoria in 1904 before the winter snow had disappeared from the lower 

 half of the glacier, which is ordinarily bare in the summer. It was noted that as 

 the surface boulders protruded through the snow a larger percentage of them 

 showed melted areas upon their northern sides, the shape and size of which sus- 

 tained a certain relation to the breadth, height, shape, and possibly position of the 

 boulders themselves. Over the melted area the snow was removed, in whole 

 or part, to the soiled surface of the glacier, so that the feature shows with 

 much clearness in the photographs secured. The phenomenon was seen 

 upon the Lefroy, as well as the Victoria, and sparingly upon the Wenkchemna 

 in midsummer, near the neVe" lines. The same thing was also seen upon the 

 snow of an avalanche which had descended from Mt. Whyte and carried along 

 some small rock fragments, which were scattered over the surface. The block 

 shown in plate xxiv, figure 4 is a gray quartzite standing 10 inches high and is 29 

 inches broad. The melted area has the same length as the rock and has a corre- 

 spondence in outline. The farther right hand corner of the rock is somewhat 

 lower than the general surface and the corresponding corner of the melted area 

 is seen to be rounded and incompletely melted. Boulders showing the phenom- 

 enon were not hard to find upon the Victoria, but were very abundant. The 

 north-south axes of ten of the areas, selected at random, gave an average 

 magnetic reading of N. 25.5 W., with less range than was shown in the case of 

 the glacial tables. The magnetic decimation of the region, as obtained by the 

 Canadian Topographic Survey, is N. 25^' E., so that these areas are oriented 

 with reference to the noonday sun, and might have been used for determining 

 approximately the meridian and the magnetic declination. The natural infer- 

 ence is that the phenomenon is due to the reflection of heat from the surface 

 of the boulders, this action being at a maximum when the sun is upon the meridian. 



3. FORMER ACTIVITY. 



a. Terminal moraines. Between the present poorly defined terminal moraine, 

 described upon page 49, and Lake Louise there occurs a series of ancient 

 terminal moraines which furnish evidence of the glacier's former extent and 

 greater activity. The first two of these moraines are remarkable in that they 

 consist of massive blocks of quartzite and sandrock, tumultuously heaped 

 together and without the usual filling of gravel, sand, and clay. The position of 

 these is shown upon the map, plate in. The spaces between the great blocks 

 enable man, or animals, to creep in between and under them and they form 

 an ideal home for the marmots. For moraines of a somewhat similar appear- 

 ance, although probably different history, in the Mount Ktaadn region Prof. 

 R. S. Tarr has used the expressive term "bear-den moraine." ' The. inner of 

 these two moraines extends obliquely across the valley from the present nose, 

 being partially overridden by the glacier and along the side of the valley nearly 

 parallel with the oblique front. It consists of what were originally massive 



1 Glaciation of Mount Ktaadn, Maine. Bulletin Geol. Soc. of Amer., vol. xi, 1900, plate 37. 



