188 Cincinnati Society of Natural History. 



some sandstones at the base, which inclose one prominent coal-seam; 

 the outcrops of this group are generally occupied b}^ valleys. The Fox 

 Hills Group consists of about 3,000 feet of heavilj^-bedded white 

 sandstones, with a few coal-seams and comparatively little cXtxy. The 

 Laramie Group, whose actual thickness is not definitel}- ascertained, 

 consists also of gra}^ and white sandstones, often iron-stained, contain- 

 ing a greater development of clay beds, and ver}^ rich in coal seams. 

 It is overlaid by an unconformable series of beds. The fauna of this 

 group is brackish, and, locall}^ even fresh water forms are found asso- 

 ciated with marine types. 



In the valle}^ of Bitter creek, the Fox Hills Group is estimated at 

 3,000 feet in thickness, and the Laramie at 6,000 feet. The latter is 

 characterized h\ the greater development of claj-ey beds, and bv the 

 great number of coal seams, and by the presence of great quantities 

 of leaves and plant remains, especially in the upper portion of the 

 series. The beds are conformable, and were evidently deposited prior 

 to the great period of plication and uplift in which the Rock}' Moun- 

 tains and the Uinta and Wahsatch ranges received their main 

 elevation. 



West of Bear River City, in Utah, along the face of the hills north 

 of Sulphur creek, are exposed outcrops of the Fox Hills and Laramie 

 Groups, from 5,000 to 7,000 feet in thickness, standing at angles of 85° 

 to 90° west, and striking' north 30° to 45° east, and consisting of 

 heavy white sandstones with conglomerate beds, and passing to the 

 westward into reddish brown sandstones. The beds of the Colorado 

 Group west of the sandstone ridge, at the bend of Sulphur creek, 

 expose a thickness not less than 5,000 or 6,000 feet. About two miles 

 west of Bear River City, a railroad-cut, through a low ridge running 

 out from the high ground forming the northeastern wall of the Sulphur 

 Creek Valle}^ shows a section of about 150 feet of beds, separated b}^ 

 an interval, bare of outcrops, from the sandstones west of Bear River 

 Cit3', but corresponding with them in strike, and standing with an incli- 

 nation of 70° to 80° to the southeast. It is formed of sandstones, marls 

 and clays, with a few bituminous and gypsiferous seams, and is 

 remarkable for the fine definition of its bedding-lines, the strata 

 varying from half an inch up to a foot or more in thickness. The strata 

 abound in fossils of fresh and brackish water tj^pes, viz. : Unio^ Cor- 

 hula, Limnaea., Canfipeloma., Viviparus^ etc. The}^ evidently belong to 

 the conformable beds of the Laramie Group, and are overlaid a short 

 distance to the north b}" horizontal strata of the Vermilion creek 

 Eocene. 



