A TYPE OF LAKE FORMATION IN CANADA 255 



convection currents to disturb the quiet of the waters, the lake 

 becomes perfectly clear by spring. 



An attempt was made to get a section of these clay deposits 

 at the lake bottom and so determine the age of the lake. It 

 seemed probable that by knowing the thickness of the annual 

 deposit, and by getting an entire section, the number of years 

 since the formation of the lake could be estimated. For this 

 purpose a piece of iron pipe about one inch inside diameter was 

 heavily weighted and fastened to a stout rope. This was lowered 

 in about two hundred feet of water and allowed to fall the last 

 fifty feet so as to carry the pipe far into the bottom. Upon 

 lifting the pipe out, and this was accomplished with great diffi- 

 culty, a core ten inches long was removed from the pipe by dry- 

 ing. Unfortunately this core did not represent the entire section 

 of the lacustrine deposits so that it would have been useless to 

 make estimates on this basis. As had been hoped, however, 

 there were clear evidences of lamination in the slightly different 

 colored bands of clay, though the structure was distorted by 

 being forced into the iron pipe. As nearly as could be counted 

 there were about one hundred bands to an inch, and on the basis 

 of 10,000 years since the last retreat of the ice, these clay 

 deposits would have to be between eight and nine feet thick. 

 With a more perfect apparatus and an entire section, the age of 

 this lake, and consequently the time since the glacial period, 

 might be quite accurately estimated. 



The Lake Louise Valley has a trend to the east as it 

 enters the Bow Valley, as though the former ice streams had 

 turned down stream and swept over the flanks of the mountain 

 on the east side of the valley, while the other side shows a sharp 

 ridge of drift descending from the base of a rock buttress 800 

 feet above the lake. This ridge carries a dam across the valley 

 mouth and slightly deflects the outlet stream to the right. The 

 outlet stream has cut down through this dam and exposed a sec- 

 tion of drift from 75 to 100 feet deep. It is typical till of hard, 

 blue clay, with angular or striated limestones, shales and quartz- 

 ites, distributed through it. 



