138 

 Columnar Section of the Ross Formation 





Thickness. 





Feet. 



Metres. 



Conformable base of Sir Donald quartzite. 



Gray, rarely rusty, thick-bedded, compact 

 quartzite, with interbeds of gray and brown- 

 ish quartzitic sandstone and grit 



Pale rusty-brown silicious phyllite or sericitic 

 quartzite, carrying in the middle a 15-metre 

 bed of gray quartzite 



1 ,200 



350 



3.7oo 



366 



107 



1 , 127 



Gray quartzite, thick-platy and homogeneous, 

 weathering gray and rusty; with interbeds 

 of hard quartzitic grit and sandstone 



Conformable top of the Nakimu limestone. 



5.250 



1 ,600 



In the grand exposures along the northwestern edge of 

 Beaver River valley the Ross formation weathers more 

 uniformly rusty but is still quartzitic; this section shows 

 an approximate thickness of 5,000 feet (1,524 m.). At 

 the summit of the Dogtooth mountains, the formation is 

 more argillaceous, while retaining its deep rusty colour 

 and numerous bands of fine quartz conglomerate or grit 

 so characteristic in the Selkirks. It is correlated with the 

 shaly to sandy beds in the upper part of the Beltian-Hector 

 formation and in the Lower Cambrian Fairview formation 

 — both exposed in the Bow River valley of the Rocky 

 mountains. Here again the geosynclinal rocks in the east 

 are more argillaceous than those contemporaneously 

 deposited in the west. 



Cambrian System. 



At the summit of the Selkirk range the Ross quartzite 

 passes gradually upwards into the Sir Donald formation. 

 This is a very homogeneous mass of quartzite, much like 



