44 GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 



fine layers, but such a deposit would be of limited thickness since it would very 

 soon be pushed outward and beyond the reach of the snow dust. The bulk of 

 the avalanched ice would come down in great heaps, which could show neither 

 original nor acquired lamination. Granting that some of the avalanched snow 

 and ice would become finely stratified, we would expect it to alternate with much 

 more that was not, and with frequent layers, produced by the direct snowfall into 

 the valley, showing the typical neVe lamination. Furthermore, the position of 

 the Lefroy upon the Mitre is such that these laminae along the sides of the former, 

 as well as over the surface, should run across the valley and should be entirely 

 conformable with the strata. 



Upon the other hand if the banding is of secondary origin and the result of 

 pressure against the valley walls, it should be entirely similar in adjacent strata 

 of the same character, exactly as found in ordinary glaciers not formed as is the 

 Lefroy, should be found near the sides of the valley and parallel with them, 

 and should show an utter disregard for the position of the Lefroy strata. In 

 ascending the Lefroy to apply our test we find a beautifully perfect and typical 

 banding upon the Aberdeen side, well shown upon the crevasse walls, under the 

 lateral moraine. The inclination of the blue bands is very steep, ranging from 

 72 to 90 and averaging 83, as they dip downwards and into the body of the 

 glacier. These bands are continuous across the gently inclined strata and cut 

 them at a high angle. Plate xn, figure 4, shows the perfectly developed bands, 

 the margin of the glacier lying to the right, but does not give the desired view 

 of the strata. Toward the centre of the Lefroy these bands become obscure 

 at the surface, or disappear entirely, but are found again upon the Lefroy side, 

 between the collecting, region and the nose of Mt. Lefroy. So far as this feature 

 is concerned the Mitre and Lefroy seem to be a unit and the evidence is all in 

 favor of the pressure theory. 



Near the nose of the Illecillewaet Glacier the blue band structure is very 

 perfectly shown about the sides, as seen in plate xin, figure i. There is no 

 lateral pressure upon either side and the bands conform with the valley floor. 

 Furthermore, they would be conformable with the strata, providing the latter 

 were present, but these have been destroyed, presumably at the ice cascade 

 farther up the slope. It may be maintained that at such a cascade it is only the 

 superficial layers that are . disrupted and that their fragments are destroyed 

 by melting, while the basal layers are preserved intact. This is undoubtedly 

 true, at times, but in the case of the Illecillewaet, the stratification, well seen 

 above the cascade, has been destroyed to the very base and it is difficult to 

 believe that the much more delicate lamination could possibly have escaped 

 destruction at the same time. Beneath this same glacier boulders are seen flut- 

 ing the under surface, as the ice is pressed against them and melted; this is shown 

 in figures i and 2, plate xxxiv. If the banding were simply the original ne"ve" 

 stratification the edges would be cut off squarely. Upon examining the ice 

 which has been pressed against a boulder there may be seen a set of bands curv- 

 ing about the stone, as though they had been there produced. 



