26 THE ROYAL SOCIETY OF CANADA 



an examination of the section in the neighbourhood of the Inter- 

 national Boundary Hne and again confirmed these results. In 1915, 

 the area in the vicinity of Proctor on Kootehay lake was carefully 

 examined for evidence of faulting. This locality was specially favour- 

 able for geological field work since the formations cross the lake al- 

 most at right angles. The formations were followed from the high 

 mountains on the east side of the lake across Pilot point and into the 

 mountains on the west side of the trench. In fact a very persistent 

 limestone band, dipping 45 degrees northwest, was used as a horizon 

 marker. If any fault exists parallel to the trench it certainly would 

 have offset this limestone band, where it crosses the band at right 

 angles. At the north end of the trench Bancroft has found no faults. 

 From the above facts, it is certain that faulting played no part in the 

 formation of the Purcell trench. In 1915, the writer advanced the 

 idea that the Selkirk mountains^ were mountain-built for the first 

 time at the close of the Jurassic. The following reasons were put forth : 



1. The present drainage bears no relation to the underlying 

 structure. 



2. The products of the erosion of these Jurassic mountains are 

 seen in the sedimentation of the Cretaceous of the neighbouring 

 Rocky Mountains to the east. The following shows the geological 

 succession of formations of the Rocky Mountains in tabular form: 



Condition 

 , Period ' Formation of Lithological character 



deposition 



Tertiary Paskapoo Freshwater . . . Sandstones. 



Edmonton Brackish and 



freshwate'. . .Sandstones and shales 



Bearpaw Marine Shales. 



Belly River Series. .Brackish Sandstones and shales. 



Colorado Marine Shales. 



Upper Blairmore. . .Subaerial Sandstones, conglomerates 



(granite and chert peb- 

 bles). 



Lower Blairmore. . .Subaerial Shales and conglomerates 



(quartzite and chert peb- 

 bles). 



[ Kootenay Subaerial Sandstones and shales. 



[ Coal. 



Upper Jurassic Fernie shales Marine Shales. 



Devonian and Carboniferous Marine Limestones and quartzites. 



Lower Palaeozoic Marine Limestones and shales. 



DiSCONFORMITY 



Pre-Cambrian / Purcell Series \„ . . \ Mainly quartzites and ar- 



(Beltian) \Galton Series / "J gilaceous quartzites. 



iSchofield, S. J., Geol. Surv., Can., Mem. 76, 1915, pp. 160-169. 



Upper Cretaceous . 



Lower Cretaceous. 



