﻿GLACIAL STUDIES IN CANADIAN ROCKIES 



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Thin sections of such ice, however, when examined with the polar- 

 iscope, reveal tin- component granules and each is seen to be a single, 

 although incomplete crystal, giving the ice mass the appearance of 

 very coarse marble. Sections cut in various direct inns from the ice 

 near the nose of the Wapta, [llecillewaet, Asulkan and Victoria 

 glaciers, showed a tendency toward a vertical arrangement ol the 

 principal optic axis. In horizontal sections of such ice from one- 

 Eourth to one-third of the granules remained dark when revolved 



Fig. 86. — Glacier capillaries, uninjected. Wapta. 



in the polariscope. From this it was concluded that there exists a 

 tendency towards orientation of the grannies, which has been 

 affirmed by some and denied by others. 



7. Capillary Structure. — Glacial ice which has not yet begun to 

 melt either externally or internally is solid and firm and contains 

 simply the air cavities enclosed in the processes of granular growth. 

 Such ice is not penetrated by water, or colored solutions, except to 

 very slight extent. When internal melting begins there is opened 

 up a more or less continuous network of delicate capillaries, situated 

 at the lines of junction of three, or more, grannies. These are cir- 



