SEETOYA MOUNTAINS. 607 



is a north and south hne running along- the western flanks of the ridge. 

 A vertical displacement along this line has exposed, on the western 

 spurs,, heavy beds of limestone in a thickness of 4,000 to 5,000 feet, which 

 are much contorted. At the northern end of the limestone bodj^, the 

 beds form the complete arch of a sharp anticHnal fold, which descends or 

 ''noses under" to the north. In the middle of the exposure, the western mem- 

 ber has been broken down, the eastern member of the fold forming steep, 

 rugged spurs under the highest point of the range, in which the limestone 

 beds dip at first about 20° to the eastward, and gradually steepen to a 

 perpendicular and even to a slightly western dip. At the southern point of 

 the limestone exposure, in a little canon just north of Seetoya Peak, the dis- 

 placement is a simple faulting of about 100 to 150 feet, which can be very 

 distinctly traced, where, in the upper portion of the limestone formation, a . 

 thickness of about 150 feet of dark limestone is bounded below by a body 

 of black shales, and above by a blue quartzite, which can be traced on 

 two adjoining spurs, both dipping about 20° to the westward. Although 

 palseontological evidence is wanting, there is little doubt that these limestones 

 belong to the Lower Coal-Measure group. 



The quartzites, which form the main crest of the ridge, consist mainly 

 of white and blue saccharoidal quartzites, containing a few thin beds of 

 interstratified limestones. Their average dip is about 25° eastward, curv- 

 ing in strike from a little east of north at the southern portion to a little 

 west of north toward the northern limits of the map. They abound in 

 slickenside-surfaces, showing remarkably beautiful striation and polish. 

 Along the eastern flanks of the ridge, overlying the quartzites, a few out- 

 crops of limestone can be distinguished under the flows of rhyolite, which 

 would represent the Upper Coal-Measure group. The lower portion of the 

 quartzite body, as it approaches the limestones, has a large proportion of 

 limy strata and beds of calcareous shales, interstratified in the quartzites. 

 On the western slopes of Seetoya Peak is a quartzitic conglomerate, which 

 apparently forms a portion of the western fold, though, owing to the dis- 

 placement and faulting, it was not possible to fix definitely its horizon. 



In a little canon to the southwest of Seetoya Peak, the line of dis- 

 placement is occupied by a dike of diorite or diabase cutting through the 



