450 GEOLOGICAL SURVEY OF THE TERRITORIES. 



-ward of Coalville, we only visited one, owned, I believe, by Mr. Joseph 

 Young, one of Brigbam Young's sous. This mine is situated iu tbe bot- 

 tom of Grass Creek valley, or caSou ; and as it seems to be exactly on the 

 line of strike of the other mines between it and Coalville, and does not 

 differ very materially in strike, dip, and thickness, there can scarcely be 

 any doubt that it is in the same bed of coal. This view is also supported 

 by the fact that the coal is immediately overlaid by a sandstone like 

 that seen over the mines between here and Coalville, and at Coalville ; 

 while we saw iu this sandstoue api^arently the same oyster observed 

 in that forming the roof of Spriggs's mine at Coalville. 



The mines in the higher part of the series, although in thinner beds 

 than the main one far below, must be of considerable value. That 

 owned by Mr. Carleton, on the west side of Weber Eiver, in division 17 

 of the section, affords a good quality of coal. The thickness of the bed 

 is about 3 feet 4 inches, with one foot of black shale and impure coal 

 above it, and over this 1 foot and 2 inches of coal. Where the shale is 

 firm enough not to require much timbering to hold it up, it can probably 

 be left as a roof to the mine; but where the shale is thin and friable, 

 the whole thickness, including the uj^per 1 foot seam of coal, up to the 

 sandstoue, will have to be taken out. Indeed it is possible that the shaly 

 parting between the two may become, at places, sufficiently carbonaceous 

 to serve for the sui)ply of fuel for machinery at the mine, and iu that case 

 it would be the best economy to work the whole thickness. The ridge at 

 this mine extends apparently without break for two miles or more, and 

 it seems probable that the coal is equally accessible throughout the 

 whole extent. 



Bear River. — On Sulphur Creek, near Bear Eiver, in Western Wyoming, 

 there are to be seen some very interesting exposures of Cretaceous rocks, 

 including valuable beds of coal. These exposures are directly on the 

 Union Pacific Eailroad, and evidently belong to the same horizon as 

 the coal series at Coalville, Utah. 



As long back as 18G0 the strata, including the coal here, were referred 

 to the Cretaceous by the writer and Mr. Henry Eugelinanu, in a paper on 

 Colonel Simpson's collections.* They were also referred to the same 

 age by Mr. King, Mr. Emmons, Dr. Hayden, and myself in 1870.t There 

 is, however, also here, associated with the above-mentioned beds, another 

 quite distinct formation, containing an entirely different group of fossils, 

 consisting of a mingling of both fresh and brackish water types, which 

 I have always considered most probably of lower Eocene age. 



While on an excursion to Wyomiug and Utah during the i)ast sum- 

 mer, accompanied by Dr. Bannister, we availed ourselves of the oppor- 

 tunity to stop at the Bear Eiver locality to examine the rocks and collect 

 fossils, and from our notes, observations, and collections, 1 have prepared 

 the accompanying section of the strata exposed there. Most of these 

 beds, it will be seen, are thrown up into a nearly vertical posture, with 

 an approximate uorth and south strike ; and the section, which is a little 

 more than oue mile in length, crosses the strike at right angles from 

 east to west. Commencing at the right hand, or eastern end of this 

 section, and going westward, we meet with the following strata: 



'Proceed. Acad. Nat. Sci., Philad., Apr., 1860, p. 130. 

 t Mr. King's and Dr. Hayden's Reports for 1870. 



