'/. Parlcinson — Lalic Basins in Alberta if British Columbia. 99 



difficult to say, unless sonndings were taken, but live rock ((jiiartzite) 

 outcrops on the trail leading down to Lake Louise, not far below the 

 level of Mirror Lake. No exit stream can be found, and the over- 

 flow is said to find its way to Lake Louise by underground channels ; 

 a statement I see no reason to doubt, but the fact is unfavourable to 

 the hypothesis that Mirror Lake is a true rock basin. 



The valley in which Lake Louise lies, 850 feet below, is clearly 

 blocked at the lower end of the lake by drift, but Wilcox states that 

 the bottom of Lake Louise is 230 feet below the very lowest part of 

 its dam. and the lower surface of its glacier must have ascended this 

 slope upon entering the Bow Valley. It is possible, then, that the 

 lake is a true rock basin. 



One other example, also of a dubious nature, remains to be 

 mentioned, viz., that from the Selkirks, near the Great Glacier, 

 and some 1,500 feet above the station of Glacier on the C.P.R., 

 directly overlooking the valley. It is called Lake Marian. Moun- 

 tains rise abruptly, with talus strewn around their bases for nearly 

 half the circumference of the lake ; in front, where the pine-clad 

 slopes plunge down to the valley beneath, a quartzite outcrops. 

 Tiiis, or a crushed grit, is the common rock of the ascent from 

 Glacier, with some outcrops of broken silvery slate. On the re- 

 maining (eastern) side live rock, if it exists, is concealed by surface 

 soil and undergrowth, and the level is low. At first I thought Lake 

 Marian to be a true rock basin, but subsequent reflection inclines 

 me to the belief that glacial deposits may exist. The slopes on the 

 south-eastern side of the lake in the dii'ection of Mount Abbott are 

 not precipitous, and it is possible that here a glacier left material 

 sufficient to retain the water. 



We are left, therefoi-e, with but one clear and certain example 

 of a rock basin, and it remains but to consider as briefly as may 

 be what causes operated in its formation. And firstly, differential 

 earth movements, as suggested by Mr. Brend for the Caernarvonshire 

 tarns, may be considered. The bedding of the rocks forming the 

 walls of the lake is remarkably well defined, and not far removed 

 from the horizontal, but on looking at the right bank from an 

 advantageous position, it becomes apparent that a slight dip up the 

 lake exists which is greater at the lower than at the upper end. As 

 the change, though slight, is abrupt, a small fault probably exists 

 at this point. 



The cirque is no doubt pre-Glacial, but it is possible that the 

 configuration of the country has been altered in quite late times. 

 Dr. .T. W. Spencer, in his well-known work on the "Origin of the 

 Basins of tlie Great Lakes in America,'" has demonstrated ' terrestrial 

 warpings ' more recent tlian the episode of the Upper Till. On the 

 western side of the continent Dr. G. M. Dawson - mentions terraces 



1 Quart. Journ. Geol. Soc, vol. xlvi (1890), p. 530. 



• "The Superficial Geology of British Columbia": Quart. Journ. Geol. Soc, 

 vol. xxxiv (1878), p. 89. See also Dr. G. M. Dawson. " On the Plivsioirraphical 

 Geology of the Rocky Mountain Region iu Canada'': Trans. Roy. Sol-. Canada, 

 vol. vii"i (1890), sect. 4, p. 68. 



