618 EEPOET UNITED STATES GEOLOGICAL SURVEY. 



ranges, appears from the few sections made, to be composed mainly of 

 massive blue limestones, witb which, a few bands of quartzite are inter- 

 laminated. 



Near Station 56 and southward, overlying conformably undoubted 

 Carboniferous strata, a series of rather shaly and somewhat arenaceous 

 beds was observed, which in the iield were referred to the Upper Car- 

 boniferous, as they were in position beneath red sandstones considered 

 to be of Triassic age. An investigation by Professor White of the few 

 fossil remains from them indicates their Triassic"? age. 



South of the Salt Eiver Eange a comparatively low Carboniferous 

 range extends to Twin Creek from the head of Smith's Fork of the 

 Bear, on the east side of Ham's Fork of Green Eiver. IsTeither these 

 rocks nor those of the Sublette Eange, referable to the Carboniferous, 

 were sufficiently studied to develop the details of their occurrence. 

 They form an antichnal. 



Freuss Eange. — In this interesting range the Carboniferous rocks, con- 

 sisting of massive limestones, showing in several sharp folds, yielded a 

 number of their characteristic fossils. North of the range, at Station 

 65, the upper portion of the formation consisted of a white quaitzite, 

 siliceous limestone, and laminated blue limestones, above which were 

 arenaceous strata with Triassic *? fossils. 



Bear Eiver Eange. — In the central portion of the Bear Eiver Mount- 

 ains massive limestones form an important part of the range. They 

 have a thickness of 5,000 -f feet. In the upper part they become some- 

 what siliceous. These beds form the Wahsatch Group of the Fortieth 

 Parallel Survey, the base of which has been referred to the Devonian 

 by the geologists of that survey. 



Ko Devonian fossils were obtained by us, and I have therefore not 

 been able to separate the formation nor to color it on the map as distinct 

 from the Carboniferous. 



Portnetif Eange and Soda Springs Sills. — The northern portion of the 

 Portneuf Eange is probably almost entirely Carboniferous in its south- 

 ern extension. A quartzite hes at the base of the section here, and the 

 central portions consist of dark-blue, gray, and lighter colored lime- 

 stone, with quartzites and siliceous limestones on top. 



In the Soda Springs HiUs, as far as seen, the Carboniferous outcrops 

 are similar to those already described. The limestones contained an 

 abundance of their characteristic fossils. 



Section of Cartoniferous. 



1. Kather compact, heavily-bedded limestones, mtli a few quartzitic layers at the base in the 



Wyoming and Salt Eiver Ranges. 

 Massive blue and gray limestone, with laminated layers at the base in the Bear Eiver Eange. 

 Blue dove colored and reddish weathering limestones in Portneuf Eange. 

 Thickness, about 5,000 feet. 



2. Quartzites in Portneuf Eange, and ia Wyoming and Salt Eiver Mountains quartzite with 

 overlying dark-blue laminated limestones in Station 65 ridge. 



This general section is based on the following detailed section : Nos. 

 9, 14, 15, IG, 17, 19, 20, 30, and 31. 



I did not recognize any beds as of Permo- Carboniferous age, nor could 

 I separate the Sub-Carboniferous from the Coal Measure limestones, as 

 none of the fossils found were typical of the lower division of the for- 

 mation. 



