28 GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 



contains a number of low islands, supporting some vegetation. The outlet 

 stream is marginal for about 500 feet and then enters the side of the glacier. 



d. General drainage brook. The subglacial and englacial streams are all 

 united into a single stream which emerges from the base of the ice at an elevation 

 of 6,127 feet and back about 1,000 feet from the real nose, upon the west side. 

 This stream cascades over the coarse blocks of the terminal moraine, receives 

 a small tributary from Mt. Whyte, and rushes headlong to the lake, one mile 

 distant, dropping some 450 feet. In comparatively recent time the dis- 

 charge was through a tunnel which is being rapidly destroyed by melting, 

 plate vin, figure 4, shows the entrance to this tunnel as it appeared in 1904 and 

 plate ix, figure 4, furnishes an interior view looking out and down the valley. 

 At this time the opening was 1 2 feet high by 7 feet broad and the tunnel could 

 be entered for a distance of 160 feet, when it appeared to have been clogged by 

 ground-morainic material. The opening narrowed rapidly toward the inner 

 end (plate ix, figure 3) and the severe melting of 1905 showed that it connected 

 with an englacial passage leading towards the main moulin. This difference 

 in the size indicates that when the ceiling of the portion of the tunnel shown in 

 plate ix, figure 4, was being fluted by torrential waters, the bed of the stream 

 was at a considerably higher level than that there shown and that the stream 

 worked its way down from an englacial to a subglacial position. The amount 

 of water discharged through this tunnel was probably no greater than that 

 at" the present time through the present exit. The floor of the tunnel, at its 

 entrance in 1904, had an elevation of 6,192 feet, or 65 feet above the present 

 place of discharge. 



During periods of minimum melting, and always in the early morning, 

 the amount of water discharged from the glacier is relatively small. Late 

 in the afternoon and evening of a day of rapid melting it gushes forth with 

 great power and volume (plate x, figure i). It was impracticable to 

 measure the amount of discharge at this exit, but measurements were made 

 at the delta where the stream enters the lake. So little additional water was 

 being received at the time from the adjacent mountain slopes that the results 

 secured represented approximately the flow from the glacier itself. An accurate 

 cross-section of the stream was secured by taking the level of the bed for each 

 foot, establishing a gauge, and determining the velocity from surface floats. 

 A calculation of the flow was made, after a week of minimum melting, by averag- 

 ing the flow at 9:00 A.M. and at 6:00 P.M. During this period there were 0.671 

 inch of rainfall near the nose of the glacier. A . similar determination was 

 made after a week of maximum melting, with 0.030 inch of rainfall. These 

 results gave 73 and 93 cubic feet per second for the average flow. At the 

 time of the minimum flow the water at the exit from the glacier was found to 

 possess 0.230 oz. of sediment to the cubic foot and 0.506 oz. during the time of 

 maximum discharge. This is enough to make the water decidedly turbid. 

 The total amount of sediment carried out daily during the maximum discharge 

 period was estimated to be about six tons, and one-third this amount for the 



