386 Johnston — Sedimentation in Lake Louise. 



ported by the streams is much greater in summer than in 

 winter. Part of the very fine material which forms the 

 upper part of the seasonal band may have been carried 

 into the lake during the summer and deposited during 

 the winter. In other cases, especially in brackish water 

 bodies, the finer part was probably transported during 

 the winter, for it could not long remain in suspension, if 

 the water was even slightly brackish. 



Seasonal deposition in aqueo-glacial sediments has been 

 well discussed by E. W. Sayles, 10 who reviews in a well 

 illustrated paper the literature on seasonal banding in 

 glacial clays, describes the banded clays in the Connecti- 

 cut valley and in Rhode Island and discusses the criteria 

 for the study of aqueo-glacial sedimentation. He con- 

 cludes that the seasonal hypothesis for the banded clays 

 is in a very strong position and that there is little danger 

 of its being abandoned. The present paper confirms this 

 conclusion. 



10 Memoirs of the Museum of Comparative Zoology, vol. 47, No. 1, Cam- 

 bridge, Mass., 1919. 



