Lake Louise, Alberta, Canada, 385 



that occasionally forms part of the seasonal layers and 

 the current marks may be accounted for in this way as 

 suggested by de Geer. Part of the sand, however, may 

 be derived from floating ice. Another factor which may 

 be of some significance in explaining the current marks 

 and minor irregularities in the seasonal bands is that, at 

 certain times of the year when the whole water of the 

 lake is at the temperature of maximum density, storms 

 may disturb the waters down to the bottom and cause 

 appreciable bottom currents. 8 Most of the material 

 composing the banded clays is fine enough to remain in 

 suspension for at least short periods in nearly still water 

 and was evidently deposited in quiet water. The lack 

 of lamination of the marine clays is probably mainly 

 due, as was pointed out in the former paper, 9 to floccula- 

 tion in salt water — an electrical phenomenon of surface 

 tension — which causes the silt and clay in suspension in 

 the river water to settle to the bottom together when the 

 two waters are mixed. 



The seasonal layers being formed in Lake Louise are 

 much thinner than most of those of the glacial lake 

 deposits which the writer has examined. Many of these 

 are one-half to one inch or even more in thickness. The 

 small thickness of the annual layers being formed in Lake 

 Louise may be accounted for by the fact that Victoria 

 glacier is only slightly active. The thickness of the 

 annual layers would evidently vary according to the dis- 

 tances from the source of supply of the material and 

 according to climatic conditions. The exact manner in 

 which the annual layers were formed probably varied in 

 different lake basins. There seems to be little doubt that 

 the coarser lower part of the band is the summer deposit 

 and the finer upper part the winter deposit, and that the 

 difference is due to variations in transporting power of 

 the streams in winter and in summer. It has long been 

 known that streams issue from some glaciers in winter 

 as well as in summer, because of friction raising the 

 temperature of the ice above the melting point or because 

 of the heat of the earth, but the amounts of material trans- 



s Xeeham and Lloyd : The life of inland -waters, Ithaca, New York, 1916, 

 p. 35. 



9 The character of the stratification of the sediments in the Eecent delta 

 of Fraser river, British Columbia, Jour, of Geol., vol. 30, p. 128, 1922. 



