NO. 5 PRE-DEVONIAN PALEOZOIC FORMATIONS 203 



tion) 285 feet (86.9 m.) thick that is subjacent to the Devonian 

 limestone. To the southwest near Elko, British Columbia, there are a 

 few feet in thickness of Lower and Middle Cambrian strata super- 

 jacent to the pre-Cambrian and a thin deposit of magnesium limestone 

 (Elko) of undetermined age beneath the Devonian.* 



The character of the displacement of the strata on the western side 

 of the Sawback Range is illustrated by plates 30, 33. The -strata 

 of plate 33 are inclined 60° to 75° to the west-southwest, whereas 

 the beds a few miles north, plates 43, 49, are inclined 40° to 60°. 



CHARACTER OF THE ROCKS 



The predominant rock of the pre-Devonian formations is calcareous. 

 In the combined Kicking Horse Canyon and Bow River sections of 

 the Bow, Goodsir, and Beaverfoot Troughs, the total thickness from 

 the pre-Cambrian to the top of the Silurian is approximately 28,000 

 feet (8,534.4 m.), distributed as follows: 



Feet Meters 



Limestones of varying character and purity 16,180 4,931-7 



Calcareous, and argillaceous shales 6,740 2,054.4 



Argillaceous and arenaceous shales 1,700 518.2 



Arenaceous shales and sandstones 3,078 938.2 



Quartzitic sandstones 600 182.9 



The limestones may be almost pure, as in the Ozarkian Mons forma- 

 tion ; siliceous, as in the Silurian Brisco formation ; dolomitic as in 

 the Upper Cambrian Bosworth formation ; more or less arenaceous 

 as in the Middle Cambrian Cathedral formation ; quartzitic as in the 

 Lower Cambrian Fort Mountain formation ; argillaceous as in the 

 Upper Cambrian Chancellor formation ; or a combination of cal- 

 careous, siliceous, arenaceous and argillaceous material. The shales 

 vary from the calcareous of the Mons to the siliceous of the Burgess 

 shale member of the Middle Cambrian Stephen formation, and the 

 argillaceous of the Chancellor to the arenaceous of the Lower Cam- 

 brian St. Piran formation. The quartzitic sandstones of the Fort 

 Mountain are underlain by a fine siliceous conglomerate of varying 

 thickness and character. 



Thoroughly washed beach sands, with a varying amount of small 

 quartz pebbles, composed the greater part of the lower beds of the 

 Fort Mountain formation. Such quartzitic sands are not known to 

 have occurred again, except as small lenses, until the transgressing 



'■ Schofield, S. J., Geol. Surv. Canada, Museum Bull. No. 2, 1914, p. 81. 



