ii7 



Alberta. Similarly, the western slope of the Coast range 

 bore heavy glaciers which formed thick and broad pied- 

 mont sheets filling Puget sound, the Strait of Georgia, 

 and Queen Charlotte sound. 



Dawson located the main accumulator of the ice-cap 

 in the interior of the Cordillera between latitudes 54 and 

 59 , and proved the northward flow from that region 

 as far as 63 N., as well as a southward flow over the 49th 

 parallel into Washington State. Locally, the ice-cap 

 sent thick distributary sheets through low cols and valleys 

 crossing the Coast range; of these the Fraser valley is 

 a signal instance. At many points the surface of the en- 

 era ice-cap is known to have risen somewhat above the 

 7,000-foot (2,134-metre) contour. Its thickness at the 

 Okanagan valley was at least 6,000 feet (1,830 m.) ; at 

 Revelstoke about 5,500 feet (1,677 m 0- 



Nothwithstanding its massive proportions, the ice- 

 cap performed comparatively little erosion. Area for area, 

 this necessarily sluggish body was incomparably less power- 

 ful in cutting into bed-rock than were the neighbouring 

 valley glaciers. These were usually much swifter because 

 occupying lines of more concentrated flow. The influ- 

 ence of such concentration, caused by mountainous topo- 

 graphy, is extremely clear in the Canadian Cordillera, 

 and the principle leaves no ground for controversy as to 

 the efficiency of glacial erosion. 



A smaller, independent ice-cap covered Vancouver 

 island, and another, or else a large number of local glaciers 

 occupied the Queen Charlotte islands. 



GENERAL STRATIGRAPHY. 



The section along the Canadian Pacific railway offers 

 an almost complete representation of the main rock systems 

 known in the Canadian Cordillera. The variety of the 

 formations is explained partly by the transverse character 

 of the section through a belted mountain chain; partly 

 by the specially extensive uplift and exposure of the oldest 

 rocks in this geological province. Only the Pliocene and 

 the Miocene fail to appear in the list of standard rock 

 systems, which here ranges from the Pre-Cambrian (pre-Bel- 

 tian) to the Pleistocene. In the succeeding table the more 

 important formations, with thicknesses, are named in 



