glaciers op the canadian rockies and selkirks. i05 



7. Drainage. 



Owing to the crevassed condition of the ice the surface streams are small, 

 dropping into the glacier, or to the bottom, before they can develop any size. 

 Over the n6v6 area the water resulting from melting, or from rains, is at once 

 absorbed. Over the ice exposed portions, during hours of melting, small rills 

 and surface brooks come into existence, carrying water with a temperature of 

 32°. No lakelets were noted upon the glaciers, or about the margins, but upon 

 the col, lying between Castor and the Dome, Mr. Wheeler found a lakelet of 

 sapphire blue water. Under ordinary conditions there is practically no marginal 

 drainage. In 1904, back some 800 feet from the nose of the eastern ice stream, 

 a small flow was visible for a short distance. From each of the three noses there 

 issue two to three drainage brooks, those from the eastern uniting with one 

 another and with the drainage from Asulkan Ridge, after which is received the 

 central flow from the middle portion of the glacier. That from the western com- 

 mensal, along with the drainage from the hanging glaciers lying farther to the west, 

 cascades into the Asulkan Valley, forming the "Seven Waterfalls." The flow 

 from the eastern nose is the strongest and carries the most sediment, considerably 

 more than the Illecillewaet. It fluctuates in volimie during the day, reaching its 

 maximum in the late afternoon, or evening, and being lowest in the early morning. 

 The combined drainage from the middle and eastern portions of the glacier, 

 along with that received from the Asulkan Ridge to the eastward, has cut a 

 gorge 30 to 40 feet deep through the soft schist. This has the appearance of 

 having been done since the withdrawal of the ice, but it may have been started 

 by a subglacial stream. Under high velocity and charged with sharp, glacial 

 sediment the cutting power of water must be rapid upon a soft schist. Its action 

 upon quartzite boulders is well seen in the bed of the brook from Asulkan 

 Ridge. 



During the last week in August in 1904 and 1905, the average of 28 observa- 

 tions upon the temperature of the water from the eastern nose was 32.42° F., the 

 range being from 32.0° to 33.0°. Two observations upon the water from the 

 middle nose, upon leaving the ice, averaged 33.0°, while from the third nose it was 

 32.8°. Before receiving the middle drainage the temperature of the brook was 36.9° 

 and after the two had united just above the schist cut the temperature was 37.8°. 

 Passing down the valley some two miles, and receiving drainage from either slope, 

 the temperature at the bridge across the Asulkan Creek averaged 42.6°. The 

 water is here turbid but assuming more or less of a greenish cast. The stream 

 from the Asulkan Ridge before receiving the flow from the glacier was found to 

 average 36.5° (20 observations). These observations seemed to indicate that 

 the maximum temperature was attained between 11:00 a.m., and 1:00 p.m., 

 and that as the volume of water increased as the day advanced the temperature 

 gradually fell. This is brought out in the table here given. 



