140 



the more silicious phase of the Ross but weathering with 

 a gray, rather than a rusty, surface. On fresh frac- 

 tures the Sir Donald quartzite varies in the colour from 

 white through pale gray and greenish-gray to dark gray, 

 rarely rusty. It is characteristically thick-bedded. Like the 

 Ross formation it is often feldspathic and is charged with 

 numerous lenses of quartz-feldspar grit and fine quartz- 

 feldspar conglomerate. Near the base there is a 53-metre 

 band of pale-rusty to gray quartz-sericite schist. 



Summit of Mt. Tupper from Tupper Crest, showing characteristic habit of the 

 Sir Donald quartzite. Photograph by Howard Palmer. 



TheTSir Donald quartzite forms most of the highest 

 summits of the Selkirk mountains and is terminated above 

 by the present erosion surface. It has yielded no fossils 

 but clearly represents the fossiliferous Lake Louise and 

 St. Piran series of the Rocky mountains. The Lower 

 Cambrian Mt. Whyte formation of the Rockies may also 

 be correlated, tentatively, with the upper beds of the Sir 

 Donald quartzite. 



The general correlation of formations in the Selkirks 

 and Rockies may be stated as follows: 



