GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 85 



standing in 1887. From their photographs taken in this year the Messrs. Vaux 

 have established the position of the ice front with reference to a very large 

 boulder resting upon this moraine. This terminal ridge swings around to the 

 north and connects with the right lateral, which is of greater age and, in the lower 

 part at least, has lost its ice core. See plates xxx and xxxi. 



d. Right lateral moraine. The ice has withdrawn from this moraine a dis- 

 tance of 400 to 500 feet, leaving a somewhat subdued boulder slope and a low 

 ridge. This becomes higher and steeper as we approach the quartzite cliff which 

 intercepts it about one-half mile back from the nose. Here the moraine is 

 double, an older one lying just outside and parallel with it. Forest trees have 

 taken possession of the crest and outer slope. The rocks in the right lateral 

 are similar to those in the left and are found to be in the same condition of 

 being rounded and bruised. Upon the rocky ledges, which carry the distribu- 

 tary noses referred to, there is spread out more or less morainic material, some 

 of which has been assorted by running water. These ledges of quartzite have 

 been much glaciated, plucked and extend up toward Perley Rock (7,898 feet). 

 For about a quarter of a mile there extends an upper double moraine to the 

 southeastward, where it disappears under the snow. The material consists of 

 rounded boulders of quartzite and chloritic schist, with a filling of glacial sand. 

 An inspection of the map shows that there is a correspondence in the arrange- 

 ment and position of the lateral moraines; there being in both cases, a higher and 

 a lower portion, separated by quartzite ledges, carrying only a sprinkling of 

 morainic material. Since the cascade in the glacial stream lies between these 

 exposures of quartzite it is probable that the ledges are continuous beneath 

 the glacier; that they have proven too hard for the glacier to remove, and so it 

 is compelled to cascade over them. 



e. Boulder pavement. Between the terminal moraine and the present nose 

 of the glacier there has been 'uncovered since 1887 a broad boulder belt, about 

 500 feet across. This consists of ground-morainic material in large part, with 

 the rock fragments which were carried englacially, or supraglacially, and de- 

 posited as the ice front receded. These boulders have been overridden by the 

 ice so lightly that they have not been disturbed, and yet a number of them were 

 glaciated while in their present position, forming what is known as a "boulder 

 pavement." About the present margin of the ice, boulders are being continually 

 uncovered which are being subjected to the same action. The ice presses against 

 the up-stream face of the boulder, and, either because of the warmth of the stone, 

 or more probably because the melting point of the ice is reduced by the pressure, or 

 because of both these agencies, an inverted trough, or fluting, is produced upon 

 the under surface of the ice, having the form of the rock. In plate xxxiv we have 

 these flutings shown in different stages of formation; in the last case (figure 2) 

 the stone was estimated to lie 70 feet back from the ice margin and was under 

 probably 50 feet of ice. Photographs taken some years ago of the "ice grotto" 

 show that it was a feature of this kind produced by an unusually large rock. 

 If the pressure were sufficient, the ice would settle in promptly upon the lee side 



