PEALE.]' DESCEIPTIVE GEOLOGY GEEEN EIVEE BASIN. 535 



out the fossiliferous shales for specimens^ wliicli tliey send to the railroad 

 for sale. Prof. E. D. Cope has described a large number of species of 

 fish from this locality.* The specimens collected by me were sent to 

 Professor Cope for identification, and the following is the list : 



Mioplosus abhreviatus. 

 Mioplosus labracoides. 

 Mio2)losus (species?). 

 Dapedoglossus testis. 

 Diplomystus humilis. 

 Diplomystus analis. 

 Priscacara pealei. 

 Friscacara serrata. 

 Priscacara serrata (young). 

 Clastes ferox. 



A few iQsects also were collected, and were sent to Prof. S. H. Scud- 

 der. Leaves also are found iu connection with the insects and fish. 

 They occur in a calcareous shale, which is easily cut when first taken out, 

 so that the specimens are generally in better shape than those obtained 

 from the shales of Green Eiver City. In the lower part of the bluff 

 from which these specimens are taken, the bright colored beds of the 

 Washatch are seen outcroppiug, although the entire section cannot be 

 seen, as their softness causes them to weather so that the debris conceals 

 the strata. The fossils are found at several horizons in the shales. 

 Near the top of the bhiff is a band of hard, bituminous, or oily shale, which 

 burns rather freely with a strong bituminous odor. The occurrence of 

 this shale in connection with the fish-beds suggests the possibility of the 

 animal origin of the oily deposit. It is brownish-black in color and on 

 the weathered surfaces a bluish-white. Its structure is very irregular 

 and seems to include fragments of sand. Portions are slightly calca- 

 reous, although it is mainly argillaceous. 



Somewhere near the head of Twin Creek, between it and Ham's Fork, 

 is the Mammoth Mine. The following notes iii regard to it were fur- 

 nished by one of the Bell brothers, who, with two brothers by the name 

 of Smith, were the discoverers of the beds iu July, 1876. The coal 

 occurs in Bell's Pass between the head of Twin Creek and Ham's Fork. 

 A thickness of 315 feet includes all the coal beds, of which there are 

 twenty-nine separated by sandstones and clays. They are from a foot 

 and a half thick to 48 feet thick. Openings have been made into each 

 bed, but none have penetrated more than about 20 feet. The strike of 

 the beds is about north and south, and the dip 30° or 40° to the west. 

 There are said to be other beds outside of this that have not been opened. 

 Nine miles farther south the same beds are said to outcrop again, but 

 with a southern dip which throws them under the Bridger road. No 

 fossUs have been found in connection with the coal beds, but it is probable 

 that the horizon is above that of the coal outcropping at the bend of 

 Ham's Fork. The latter is probably in the upper ijart of the Fox Hills 

 Group or the lower ijart of the Laramie Group. As to its relation to the 

 coal of Evanston and the coal exposed lower down Twin Creek, nothing 

 can at present be said. The men from whom the description was obtained 

 think it is not the same bed. The coal appears to he of good quality 

 with a good luster, and does not seem to be much affected by the 

 weather. I was also shown specimens of a softer coal from layers that 

 were said to rest uncomformably on the beds containing ihe mammoth 

 beds. 



* Bunetins U. S. Geol. Survey, vol. iii, No. 4, p. 807 ; vol. iv, No. 1, p. G7. 



