GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. IOI 



by which it is delivered to the main stream from the Pass, as previously noted, 

 upon a level with its surface. This ne've'-covered glacier sustains the same relation 

 to the Asulkan that the Collie and Gordon glaciers do to the Yoho. Between 

 the crest of the moraine and the glacier there intervenes a steep boulder slope, 

 about 300 feet broad in the lower portion near the nose, but narrowing gradually 

 for a half-mile, when the moraine and ice meet. Opposite the nose, upon the 

 eastern side there is an outcrop of a silvery schist, with its strata upon edge, 

 which has been glaciated and plucked. 



The development of the left lateral of the eastern stream from a former medial 

 has already been described and its very straight course obliquely across the valley 

 been accounted for. Originally, this moraine may have been largely subglacial, 

 or englacial, the material being derived from the basal layers of the ice. The 

 slope of the valley floor is northward, while this lower half-mile of the moraine 

 bears northeastward. After making the very abrupt bend noted, the moraine 

 continues for a quarter-mile farther, resting upon the rocky ridge of quartzite 

 and a greenish schist. This ridge raises the base of the middle stream above 

 the present surface of this portion of the eastern stream. The moraine consists 

 very largely of ground moraine, supplied apparently in large part by the middle 

 ice stream, but instead of clay the filling is a glacial sand. The finer material 

 may have been removed by currents too gentle to transport this sand. The 

 inner slope of the moraine is steep, the outer is more gentle down to the drainage 

 brook from the middle nose. The crest of the moraine rises 125 to 150 feet above 

 the floor of this valley. About one-quarter mile back from the nose this moraine 

 begins to shed its cover of rock debris, revealing in a most interesting manner 

 the real structure of such a moraine. From this point up the valley the moraine 

 is a typical, sharp-crested structure (plate xxxix, figure i), but here the debris has 

 begun to slip to either side, forming a double ridge with a continuous ice crest 

 between. Plate XL, figure i, gives a view of this exposed ice core, looking up the 

 glacier along the inner side. The highest portion of the ice ridge attains a height 

 of 25 to 30 feet, which is being rapidly acted upon by the sun in midsummer. 

 Where it has been longest exposed the ice has melted below the general level of the 

 glacier, forming a depression with a ridge of rock d6bris upon either side, the 

 outermost one being quite prominent. Into the depression the material from 

 either side has begun to roll and slide, thus protecting the ice at the bottom of the 

 depression from the sun. Had the thickness of the ice proved sufficient, in 

 time the rock debris would have gotten back, in large part, into the depression, 

 allowing the ice to melt upon either side and starting again the formation of a 

 single-crested, typical moraine. Thus it appears that moraines may, under certain 

 circumstances, pass through the same series of stages as those described for sur- 

 face lakelets upon page 5 7 of this report. 



About the eastern nose there has been pushed up a ridge of ground moraine, 

 from 12 to 15 feet high, into which the ice nose plunges and buries itself. Upon 

 this ridge minor ridges, but a foot or two in height, also occur, as seen in plate XL, 

 figure 2 . At times the nose is so deeply buried that it is difficult to find it for pur- 



