207 

 Miles and f j-^ trench has been deepened and widened 



Kilometres. _. . , . • i i r • i i 



by Glacial erosion, with the resulting devel- 

 opment of hanging valleys. The railway 

 crosses several of these, in which the streams 

 have already cut deep gorges in the schists 

 and fissile quartzites. The walls of the trench, 

 especial^ on the southwest side, are ornamented 

 with scores of cirques, many being still deepened 

 by living glaciers. 



Excepting a few of the highest peaks, the 

 entire mountain wall visible on the Purcell 

 side of the trench is composed of the thick 

 Cougar formation dipping steeply to the E.N.E. 

 All the rocks in the lower slopes of the Selkirk 

 wall belong to the same formation, here dipping 

 steeply under the Nakimu limestone and the 

 massive Ross quartzite, of which most of the 

 highest peaks of the Selkirks are constituted. 



78-0 m. Bear Creek station — Alt. 3,663 ft. (1116 

 125-5 km. m.). Below this point, near the confluence 

 of Bear creek and Beaver river, the railway 

 company is about to pierce a two-track tunnel, 

 7 • 5 kilometres (4 • 6 miles) in length. It will cross 

 the main divide of the Selkirks and emerge at the 

 railway loop near Glacier. One of the main 

 objects of this boring is to cut out of the line of 

 traffic the long chain of yet more expensive snow- 

 sheds now necessary between Bear Creek and 

 Rogers Pass stations. 



Beyond Bear Creek station the line turns up 

 the creek and crosses the summit syncline of 

 the Selkirk range. The upper beds of the 

 Cougar formation and the Nakimu limestone 

 are quickly traversed. On the left, above the 

 forest of the canyon bottom, can be seen the 

 thick rusty quartzites of the Ross formation, 

 overlain by the gray, likewise massive, Sir 

 Donald quartzite. The impressive horn of 

 Mount Macdonald is composed of this youngest 

 member of the Selkirk series, there forming 

 an open, subsidiary syncline, which is continued 

 into the still invisible peaks of Mt. Tupper 

 on the north. 



