47 



stones of Pre-Cambrian, and Cambrian age. At various 

 horizons in the above series, shallow water character- 

 istics, including ripple marks, mud cracks, and casts of 

 salt crystals, are very common. The Purcell series extends 

 across the International Boundar}^ line into Idaho and 

 Montana, while to the north geological exploration has, 

 up to this time, been insufficient for the exact determina- 

 tion of its extension in that direction. To the west, on 

 account of batholithic intrusions, the relations are not 

 very clear, but there is sufficient evidence to prove the 

 existence of numerous patches of "Archean" schists on 

 the slopes of the Purcell trench (Kootenay Lake valley). 

 This ancient acidic terrane probably represents part at 

 least of the old land from which the quartzitic Purcell 

 series was derived. The stratified members of the Purcell 

 range pass under the younger formations of the Rocky 

 mountains to the east. 



The small cross-cutting bodies of granite and porphy- 

 ritic granite, which intrude the Purcell series, are considered 

 to be small cupola-like stocks, bearing a genetic relation- 

 ship to the great West Kootenay granite batholith des- 

 scribed in the succeeding section of this guide book. 



TABULAR DESCRIPTION OF FORMATIONS. 



Pleistocene and Recent Unconsolidated gravels and sands. 



Unconformity. 



Jurassic? Dyke intrusion: aplites, lampro- 



phyrs and porphyritic granite. 



Kootenay granite Granite and porphyritic granite. 



Mississippian. Wardner limestone. . Grey limestone. Thickness i,ooo 



_+ ft. (305-fm.). 



Devonian Limestone and shale. Thickness 



500 -I- ft. (150-l-m.). 



Roosville formation. . .Green siliceous argillites. Thick- 

 ness 600 ft. (183 m.) (Daly). 



Phillips formation Purplish-red and green siliceous 



argillites and sandstones. Thick- 

 ness 550 ft. (167 m.) (Daly). 

 Cambrian? Gateway formation ... Light grey quartzites, siliceous 



dolomites and limestone. Thick- 

 ness 2,025 ft. (617 m.) (Daly). 



Purcell lava Amygdaloidal basalt. Thicknees 



300 ft. (91 m.). 



Siyeh formation Thin-bedded green and purple 



mud cracked shales; some lime- 

 stone. Thickness 4,000 ft. 

 (1,220 m.). (Daly). 



