OROGRAPHY OF THE SELKIRK RANGE. 175 



tained in it are those of the Selkirk series, which is believed to represent 

 the upper part of the Bow River series, together with the whole of the Castle 

 Mountain group of the Rocky Mountain section. The position of the main 

 axis of this synclinal nearly corresponds with Loop creek, on the railway, to 

 the west of Glacier station, while a subordinate synclinal trough runs im- 

 mediately to the east of the same station and nearly coincides with the actual 

 watershed in the pass. 



The eastern edge of this synclinal is believed to be bounded by a great 

 fault, which is supposed to cut the line of railway near Cedar creek (about a 

 mile and a half below Surprise creek) and to run on southward along the 

 upper part of Beaver valley. This fault seems to have the character of a 

 number of those found by Mr. McConnell in an adjacent part of the Rocky 

 Mountains, viz., that of a fractured anticlinal, thrust up on the west side in 

 consequence of pressure acting from that direction. 



To the east of this great fault, the section shown in figure 1 must yet be 

 considered largely hypothetical, as the structure here becomes more compli- 

 cated and there is reason to suspect further extensive faulting. There are, 

 however, grounds for the belief that, in a wide additional synclinal on this 

 flank of the range, together with the repetition of a great part of the Selkirk 

 group, still higher strata representing the Gi^aptolite-hesirlng shales and the 

 Halysites beds of the Rocky Mountains are included. The section ends on 

 the east at the upper Columbia valley, the line of which is coincident with an 

 important anticlinal exposing rocks of the Castle Mountain series, which dip 

 westward into the base of the Selkirks and eastward into the opposite base 

 of the Rocky Mountains. 



Thickness. 



If the writer is correct in attributing a total thickness of about 40,000 feet 

 to the Cambrian (with such part of the Cambro-Silurian as may be included 

 in the upper portion of the Castle Mountain group) of the Selkirk range, 

 the entire thickness of the Paleozoic obtained by adding to this that of the 

 remaining higher members of the adjacent part of the Rocky Mountains 

 would be about 49,000 feet. Supplementing this with the thickness of the 

 Kootanie and other formations of the Cretaceous, seen either in the Rocky 

 Mountains or in the neighboring foot-hills toward the east, we obtain a 

 total of 69,000 feet. 



Though, however, the sections which give this enormous aggregate are all 

 comprised Avithin a distance, measured across the axis of disturbance, of little 

 more than 100 miles, it is improbable that the whole of the beds in their 

 maximum thickness ever formed a single column. The Cambrian evidently 

 thickens greatly at its western margin, where not only has the upper part of 

 the Paleozoic not yet been found, but where also there is reason to believe 



