THE PURCELL RANGE AND THE ROCKY MOUNTAINS 133 



of my study do not harmonize with this view. The structure 

 should be considered in three divisions. 



I. The northern part. — In the northern part, the trench is 

 certainly defined by structural features. While the structure 

 varies considerably, there are some features which hold for the 

 entire distance. There is, for example, intense folding on both 

 sides of the trench. The axes of the folds in most cases dip away 

 from the trench, and in places are overturned (Fig. 2). 



Most of the faults are thrust faults. On the west side most of 

 these have west-dipping fault planes. On the east, most of the 



Fig. 2. — Ideal section of folding 



thrusts have east-dipping planes. There is a very large thrust 

 fault, which either borders or is found in the trench from Canal 

 Flats almost to Parsons. This fault causes the semimetamorphic 

 series of pre-Cambrian and early Cambrian age to be thrust over 

 against the topmost beds of a thick Ordovician series on the east. 

 At Harrogate (Fig. 3) there are two west-dripping thrust faults 

 each with a displacement of more than 6,000 feet. This great 

 fault probably does not exist north of Parsons. At Beavermouth, 

 25 miles northwest of Golden, Daly considered that the upper 

 Cambrian-Ordovician series on the east was separated from the 

 Cougar Quartzite on the west by a normal fault of 15,000 feet 

 displacement. In a section in Canyon Creek (Fig. 4) near Golden, 

 the same formations were found as those occurring on the two sides 

 of the fault at Beavermouth, and here there is no fault and the 

 formations follow each other in normal stratigraphic succession. 



