6 GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 



crystallines and their" supposed equivalency with strata of known Cambrian 

 age in the Rockies to the eastward. The crest of the Selkirks, the region in 

 which occur our snowfields and glaciers, consists of the folded Selkirk series, 

 with an estimated thickness of 25,000 feet and believed to be of Cambro-Silurian 

 age. The strata have been forced into a synclinal fold, which terminates to 

 the eastward by a thrust fault, produced by the western half of a sharp anticline 

 being thrust upward with reference to the eastern half. The rocks consist of 

 gray schists and quartzites, passing into grits and conglomerates which weather 

 to pale yellowish or brownish colors. The latter are often more or less schistose 

 from pressure and other metamqrphic agencies, silvery mica, or sericite, being 

 developed. At times the strata are wrinkled and contorted. 



Passing into the Rockies, to the eastward, we find them made up very 

 largely of the representatives of the Nisconlith and Selkirk series just described, 

 but known in the report of Dawson as the Bow River and Castle Mountain series. 

 In the western part of the Rockies, adjacent to the Columbia, the upper and 

 younger of the two is continued from the Selkirks, showing crumpling and folding, 

 with metamorphism, but without faulting. The rocks are dipping eastward 

 and have their "strike" parallel with the mountain ranges. Along the center 

 of the range the folds are broad and sweeping, while eastward, for about 25 

 miles, there is a succession of thrust faults, running parallel with the ranges, 

 the maximum vertical displacement being estimated at 15,000 feet. McConnell 

 made out seven of these faxilts, giving rise to a series of massive mountain 

 blocks Cresting in succession upon one another and forming escarpments to the 

 east and relatively gentle slopes to the west. It was to this type of mountain 

 that Leslie Stephen applied the suggestive term "writing-desk." 



The ranges making up the central portion of the Rockies are of the Castle 

 Mountain series (Selkirk series) and of Cambro-Silurian age. They are more 

 regular and depart less from the_ horizontal than the strata to the east and 

 west. Mt. Stephen, on the line of the railway, gives a 5,ooo-foot section of the 

 series, one shaly band being "remarkably rich in Cambrian trilobites. The total 

 thickness of the series is estimated at 10,000 feet, as compared with 25,000 

 feet in the Selkirks, and consists of limestone and dolomite, with calcareous 

 schists and shales. These rocks give the steep-sided, massive, block-like cliffs, 

 typically shown in Castle Mountain, which has furnished the name for the 

 series. These rocks extend lengthwise of the central ranges to the Yoho 

 Glacier at the north and the Victoria and Wenkchemna glaciers to the south. 

 At the base of Mt. Stephen, at the head of Lake Louise, and in the Bow River, 

 there has been brought up from below by an anticlinal fold the "Bow River 

 Group, " or Nisconlith series of the Selkirks. :This is of Cambrian age, estimated 

 .at 10,000 feet in thickness, and consists of quartzites and conglomerates, with 

 dark gray, purplish, and greenish .argillites. 



b. Physiographic changes. When viewed from a high elevation the rough 

 ridges and jagged peaks appear to blend, as far as the eye can reach, into a great 

 plateau with ^ a notably even sky-line (pi. n), giving the appearance of an 



