﻿SHERZER] GLACIAL STUDIES IX CANADIAN ROCKIES 463 



an area <>l perhaps two square miles and a vertical fronl of 200 to 

 400 ft. Fragments of ice, frequentl} as large as a city block, arc 

 crowded over the cliff and fall a distance of [,200 to [,500 ft., carry- 

 ing with them more or less ground moraine and being ground into 

 fragments by the force of the fall (fig. 64). The medial moraine 

 also contains a certain amount of similar material which has been 

 derived in the same manner from the hanging glacier upon Alt. 

 Lefroy. Figure 70 shows this emerging through the snow and ice 

 near the nose of Lefroy, from where it can he traced into the medial 

 moraine, The right lateral is made up still more largely of this 

 same stony till arranged in two or three sharply crested ridges, 

 which may be followed continuously around the base of Alt. Aber- 

 deen, where it passes into the right lateral of the tributary (pi. 

 lx). There are a number of couloirs running up the side of Aber- 

 deen, at the base of which detrital cones of angular debris are being 

 built upon the ice hut there are no ice fields upon the mountain (pi. 

 lxi, b) to supply any ground moraine as in the two preceding cases. 

 Many hours were spent in staring at these till ridges, diving beneath 

 the great rubbish heap plainly derived from Aberdeen, and in trying 

 to understand how the tributary could get its ground moraine upon 

 its own back and arrange it in ridges parallel with its side. The 

 matter remained a mystery until the last day of the five weeks' camp 

 in the valley. A climb the day before up the side of Mt. Whyte to 

 the Devil's Thumb revealed a feature which had hitherto escaped 

 our observation, and the investigation of this furnished what we 

 believe to be the real explanation of the puzzling phenomenon. 



8. Parasitic Glacier. — The steep snow slopes upon either side 

 of the Mitre give rise to two small ice streams which remain per- 

 manently covered with snow. These unite to form a single glacier 

 (pi. lxii), which is also snow clad during the year but farther down 

 becomes bare during the summer and reveals a very weak medial 

 moraine. For this glacier the name Mitre, originally used by Allen, 

 should be retained, ft flows lazily down the valley for about a 

 mile between Mts. Lefroy and Aberdeen, joins the Victoria and 

 suffers much compression as previously noted. From the hanging 

 glacier upon the eastern shoulder of Lefroy it receives a relatively 

 large quantity of snow and ice which is heaped up along the base of 

 this mountain and gives rise to another glacier which is not only nour- 

 ished differently, but has a different direction of motion, a different 

 set of strata and a different rate of velocities (pi. lxiii). It is for this 

 overlying, parasitic glacier that the name Lefroy may best be used. 

 Its movement is across the Mitre, but with reference to the valley 



