306 



STRUCTURAL GEOLOGY OF NORTH AMERICA 



ROCKY MOUNTAINS WEST OF BANFF 



B 



DOC-TOOTH 



MOUNTAINS 

 ? ... 





'^2 .!.*-*' ' +* 



f^ '•.'••.'•.'-"--"-" 



ROCKY MTN TRENCH VAN HORNE MOUNTAINS 



MC G1LLIVRAY RANGE 



ROCKY MOUNTAINS ALONG THE 49TH PARALLEL 



ROCKY MOUNTAIN TRENCH GALTON RANGE 



MACOONALD RANGE 



SCALE IN MILES 



Fig. 20.3. Sections through the Canadian Rockies from the Rocky Mountain Trench to the Plains. 



Section B— B' after Evans, 1932. 1, Beltian (?); 2, Cambrian; 3, Ordovician and Silurian; 4, 

 Devonian and Carboniferous; 5, Mesozoic; 6, Edmonton (Montanan); 7, Paskapoo (late Paleocene). 



Section K-K' after Daly, 1912. 1, Waterton dolomite; 2, Altyn limestone (1 and 2 Beltian); 

 3, Appekunny argillite; 3a, Hefty sandstone; 3b, MacDonald argillite; 4, Grinnell argillite; 4a, 



formations involved. One part is made up almost entirely of the forma- 

 tions of the great Beltian group, and the other of Paleozoic and Mesozoic 

 formations. The two parts are designated by cross ruling (Beltian) and 

 vertical ruling (Paleozoic and Mesozoic) on the map, Fig. 20.2. The 

 Beltian division lies to the west except at the international boundary, 

 where it extends to the east front of the mountain belt and adjoins the 

 foothills belt, thus dividing the Paleozoic and Mesozoic division into a 

 northern (Canadian) and southern (Montana) segment. 



The stratigraphy and structure of the mountain belt are shown in a 



Wigwam sandstone and argillite (3, 3a, 3b, 4, and 4a Lower Cambrian); 5, Siyeh limestone; 6, 

 Purcell lava; 7, Sheppard dolomite; 7a, Gateway argillite; 8, Kintla argillite; 8a, Phillips argillite 

 and quartzite; 8b, Roosville argillite (5, 6, 7, 7a, 8, 8a, and 8b Middle Cambrian); 9, Mississip- 

 pian and Devonian limestone; 10, Kishenehn clays (Miocene). 



series of cross sections in Figs. 20.3 to 20.7. Section B-B', K-K', G-G', 

 and I— I' are especially intended to typify the structures in southern Can- 

 ada and in Montana. 



A great thrust fault is the dominant feature along the eastern margin of 

 the mountain belt. At the east base of the Lewis and Lewis and Clark 

 ranges it is called the Lewis thrust and has been extended southward 150 

 miles in Montana to the Lombard thrust (Clapp, 1932) and northward 

 from the international border at least 150 miles (Calgary Sheet, of the 

 Canadian Geological Survey, Alberta, 1928). The great fault has several 



