576 REPORT UNITED STATES GEOLOGICAL SURVEY. 



These prove tlie beds to be the same as the Bear Eiver Laramie groiij). 



On the top of the hill in which they outcrop, Wahsatch red conglom- 

 erates and sandstones dip 10° to 15° to the eastward. Succeeding these 

 reddish beds are white sandstones. 



Underlying bed ]Sb. 1 is a considerable thickness of light sandstones, 

 in which there is a thin coal-bed. Samjjson Tarns, of San Francisco, is 

 president of the company. No work was being done on the mine at the 

 time of my visit. Several buildings have been erected ; also an oven for 

 coking the coal. The coal has to be pulverized and washed before 

 coking. This coal-bed is probably the same noted on Smith's Fork, 20 

 miles farther north. West of the hill in which the coal outcrops is a 

 rather broad sage-brush-covered valley, and then another ridge in which 

 sandstones and limestones outcrop, showing an anticlinal fold, beyond 

 which is a gentle synclinal and the eastern side of a second anticlinal. 

 The latter forms low bluffs facing the Bear. Farther south these beds 

 rise into a high ridge which, on the map of the Fortieth Parallel survey, 

 is colored Upper Carboniferous.* Speaking of this ridge, Mr. Emmons 

 says : t " But little opportunity was afforded for the examination of this 

 somewhat isolated body of limestone, and it has been referred to the 

 Upper Coal-Measure limestone on no palseontological or direct strati- 

 graphical evidence, but solely from its relative position with regard to 

 the Silurian and Cambrian bodies on the west side of Bear Eiver 

 Plateau." I have colored a portion of them Jurassic or Jura-Trias from 

 evidence obtained on Smith's Fork and in the Bear Lake Plateau, 

 which reveals the presence of several folds in the rocks underlying 

 the plateau, which is the northern continuation of the eastern side of 

 the Bear Eiver Plateau. The limestones outcropping in the bluff near 

 Bear Eiver, and which form the prominent ridge to the southward, I 

 have colored Carboniferous, corresponding to the coloring of King's map. 



What the exact relation is between the Laramie Oroup and the 

 Jurassic I am unable to determine with the data from the few points I 

 was able to visit. There appears at some places to be an unconform- 

 ability, and at others the whole Cretaceous series may be present between 

 them. This region is one that will have to be carefully investigated in 

 considerable detail before it can be determined. The Wahsatch that 

 outcrops east of the coal-mine does not extend far to the northward. 



On the east side of the valley, between Twin Creek and Sublette 

 Creek, are several outcrops of sandstone that have been referred to the 

 Laramie Group. 



A rough wagon-road crosses from Ham's Fork to the head of Twin 

 Creek, and follows the latter to the Bear. The south side of Twin Creek, 

 at the head, has inesas with cappings of Green Eiver shale that extend 

 southward beyond our line. 



Sublette's Creek comes into the Bear 16 miles north of Twin Creek. It 

 heads north of Eock Creek on the west side of the ridge already de- 

 scribed. The wagon-road from Green Eiver Yalley comes down its 

 southern branch, and when we w^ere ia the valley, in June, large droves 

 of cattle were being driven over the road. Near the mouth of the creek 

 there is a small two years old settlement of Mormons. The Upper Bear 

 Eiver Valley makes a good summer range for cattle, but in winter it is 

 necessary to feed at the rate of about a ton and a half of hay per head. 

 While we were in the valley, in the latter part of June, there were heavy 

 frosts every night, and we had a snow-squall about the 1st of July. The 

 settlers say that it was exceptional weather, although they all agree that 



* Exploration Fortietli Parallel, Atlas Map III, west half. 

 t Exploration Fortieth Parallel, Vol. II, page 338. 



