ADVANCE AND RETREAT OF CANADIAN GLACIERS 731 



Features common to the preceding glaciers. — These glaciers each 

 have a main hne of drainage coming from beneath an arch of ice, but 

 only a portion of the drainage comes directly into this channel. Water 

 escapes through the bordering debris at the front and sides, and can 

 often be heard trickling beneath the drift. The subglacial drainage 

 of the Victoria glacier has been changed, a long cave showing the 

 position of a former exit. No superglacial drainage was observed. 



It is characteristic of all of these glaciers that their gradients are 



, Fig. 6. — Glacier in Consolation Valley. 



low; that their centers are but slightly higher than their sides; that 

 their fronts are nearly vertical; and that of late they have retreated 

 Httle, if at all. The cliff glaciers which feed them are 2,500 feet or 

 more above the level of the valley glaciers below, and the lower hmit 

 of the glaciers is at about 6,000 feet. 



The material with which their surfaces are covered is angular and 

 talus-hke. It is frequently stated that superglacial material is highly 

 oxidized, and that by this characteristic it may be distinguished from 

 subglacial material in the deposits of the glacial epoch. 



Among the glaciers of the eastern Canadian Rockies the super- 

 glacial material accumulates by falling on the ice in steep, narrow 

 valleys, as in the instances just described. In no case was the amount 

 of oxidation found to be -extensive. It was usually apparently less 



