GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 39 



region of accumulation, directly beneath the front of the hanging glacier. In 

 the lower part of the glacier this dip averages 22°, ranging from 12° to 26°, 

 while farther up-stream the dip is more gentle, only 5° to 10°, as well seen 

 in the crevasse walls. The Mitre Glacier, near the junction of its two feeding 

 streams, is crevassed and faulted and displays a very regular stratification 

 (plate VII, figure 2). 



b. Dirt zones. Upon a moderately steep slope, such as is found upon the 

 lower Lefroy, the outcropping edges of the strata, somewhat differently charged 

 with debris, give rise to broad contrasting zones which pass evenly and symmetri- 

 cally around the slope. As generally seen these bands are convex in the direction 

 of flow, but irregularities in the surface slope of the ice, or in the angles at which 

 the strata come to the surface, may make them concave down-stream for portions, 

 at least, of their course (plate xi, figure 2) . The upper edge of one zone upon the 

 Lefroy contrasts very strongly with the adjacent layer, as shown in plate iv, 

 figure 2. It was the abnormal position of this line, first seen from the Devil's 

 Thumb, that furnished the clue needed to decipher the relation of the Lefroy to the 

 Mitre Glacier. A nearer view of this zone line, and two adjacent ones, is shown 

 in plate viii, figure i, and a still nearer view in plate xi, figure i. Because of the 

 irregularity and small size of the strata, as well as the debris covering, the phe- 

 nomenon is not well seen upon the Victoria. At the place where it should show 

 the best it is, furthermore, obscured by the dirt bands of Forbes, with which 

 the zones are often confused. These two feattires are so different in origin and 

 significance, yet often so similar in appearance, that they should be sharply 

 separated in the field and in descriptions of glaciers. Plate iv, figure 2 shows 

 the dirt zones, upon the Lefroy, at the left, and the dirt bands, upon the Victoria, 

 in the middle foreground. 



c. Granular structure. A lump of ice from the bod}^of a stratum, which has 

 not yet begun to show any signs of melting, is compact, fii-m, brittle, without cleav- 

 age, and beautifully blue by transmitted light. It appears quite homogeneous 

 except for the presence of air sjDaces, which may be sparingly and in-egularly 

 scattered through the ice, or they may be arranged in seams, to be presently 

 described. Under the polariscope, in thin slices, the ice is seen to be crystalline 

 in structure and made up of closely pressed polyhedrons, ranging in size from 

 hazel nuts to goose eggs. These polyhedrons are the so-called glacial granules, 

 that may be traced back to the neve, growing smaller and smaller, upon an 

 average, as we recede from the nose. They fit tightly together, interlocking 

 perfectly, have curved rather than plane faces, and show no spaces nor signs of 

 any cementing material between the individual granules. There seemed to be a 

 correspondence between the size of the glacier and the size of the granules seen 

 about the nose, the largest granules being observed in the lUecillewaet and Yoho 

 glaciers, in the case of the latter ranging from 0.2 inch to 2.75 inches and averaging 

 about one inch. From the fact that such granules occur in no other foma of ice, 

 that they may be traced back to the neve, becoming smaller and smaller and 

 more numerous, the inference is reasonable that, in some way, these granules 



