26 GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 



and refrozen, binding the granules together into an ice conglomerate. Where 

 the ice itself is exposed and crevasses absent, the melted ice and rainfall are 

 concentrated into more or less well denned channels, which persist from season 

 to season. In the early morning the glacier is impressively quiet, the ice is dry, 

 and many of the small pools are frozen over with a thin layer of ice. When the 

 summer sun enters the valley the exposed ice becomes moist, small trickles of 

 water unite into rills, that grow larger and larger from the union of innumerable 

 others, and these form still larger brooks which empty their clear, ice-cold waters 

 into the main drainage channels and, after a day of rapid melting, we have here 

 roaring torrents. These streams slowly cut their way into the solid ice by 

 mechanical erosion, assisted by the rock fragments which the water is able to 

 move along, and by melting. The water being apparently at the melting point 

 of the ice, 32 F., it is incapable of imparting heat to that over which it flows 

 and the melting must arise from the conversion of its kinetic energy into heat. 

 Such heat would be imparted to the ice, rendered latent in the process of lique- 

 faction and the temperature of the water would not be sensibly raised. The 

 question arose in the mind of the writer while studying these ice streams 

 whether water at 32 is capable of dissolving ice at the same temperature, as 

 it might dissolve rock salt over which it was flowing. So far as he has been able 

 to learn the question has not been investigated, but if water does have any such 

 effect upon ice under these conditions, it would help to explain the formation 

 of these ice channels. 



In the upper part of their courses these stream beds are generally free from 

 debris and quite straight, but as the bed is broadened, boulders, too large for 

 the stream to handle, slide in from the surface and the stream is compelled to 

 go around. In this way a system of meanders is formed, as shown in plate 

 vin, figure 3, and the ice banks are rendered steep and, here and there, undercut 

 by the rushing water. In the lower portions of the course the bed may contain 

 considerable rock debris, but this has simply slid down from the surface and 

 nowhere suggests an aggrading action of the stream. When the stream channel 

 is contracted for any reason, the level of the water is raised, its velocity increased 

 in consequence, and an ice basin cut out upon the down-stream side, filled with 

 more quiet water. This is suggestive of the manner in which the Lake Louise 

 rock basin, to be later described, may have originated when the entire valley 

 was ice-filled. 



In portions of the glacier intersected by crevasses it is obvious that surface 

 streams, of any considerable size, cannot develop. The water escapes by an 

 englacial or subglacial tunnel, to reappear at or near the nose. When a stream 

 encounters such a crevasse, from which there is drainage beneath, it forms a 

 small cascade and begins to cut a channel in the vertical face of the crevasse 

 wall. If the velocity and volume of the water are sufficient, a corresponding 

 channel may be produced in the opposite wall. As the lips of the crevasse 

 are subsequently brought together by movements of the ice body, and the 

 crevasse is healed, this small vertical channel persists and still furnishes an 



