S. F. Emmons — Little Cottonwood Granite. 143 



in character and found the limestones in contact with the 

 latter exceedingly metamorphosed. He does not, however, 

 appear to have found any evidence of intrusive nature at the 

 actual contact of the Cottonwood granite body with the Cam- 

 brian quartzite. In reviewing the published evidence on the 

 subject, he is more inclined to favor the view favored by 

 Geikie than that of the 40th Parallel geologists, though he 

 admits that he does not regard the objections to the latter view 

 of so insuperable a nature as did Geikie. 



In the past few seasons several pieces of Survey w^ork have 

 been carried on under my supervision in this portion of Utah, 

 and I have taken advantage of the opportunity of having 

 younger legs than my own at my disposal to have the more 

 inaccessible portions of the granite contact along Little wood 

 Canyon more closely investigated. 



Already in the summer of 1900, at the close of his field 

 work in Bingham Canyon, Mr. J. M. Boutwell at my request 

 examined the contact of granite and quartzite on the south 

 face of the Twin Peak ridge, a few miles below Alta, and 

 found several apophyses of granite cutting into the quartzite 

 beds above the contact. Mr. Boutwell courteously refrained 

 from publishing the results of his examination until I should 

 have an opportunity of personally examining the contact. 

 This occurred during the past summer, when Mr. Boutwell's 

 party was making a survey of the Park City district, within a 

 few days' ride of this locality, and the object of this paper is 

 to state the result of this examination. 



That the Cottonwood granite body is intrusive in the Cam- 

 brian quartzite is proved by the existence of apophyses of the 

 former running across the bedding of the latter for some 

 distance and in one observed instance spreading out again 

 between the beds in a considerable body. 



On the other hand, no metamorphism of the contact could 

 be distinguished megascopically, and in the canyon bottom the 

 upper surface of the granite is smooth and even, conforming 

 with the bedding planes of quartzite, while small, rounded peb- 

 bles of a granitoid rock are found in the bed of quartzite 

 immediately above the contact. At the mouth of the canyon 

 the western contact of the granite body with the Archean 

 schists is much more distinctly intrusive, being very ragged 

 and uneven, while fragments of the former, both large and 

 small, are included within the granite. 



For a distance of over a mile above the eastern contact of 

 the granite, quartzites and limestones, dipping steeply east- 

 ward, occupy the bed and sweep up on either wall of the 

 canyon, thus separating the Cottonwood from the Clayton 

 Peak eruptive body by an estimated thickness of two to three 

 thousand feet of sedimentary beds. 



