132 . Cretaceous. 



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

 the outcrops of this group are generally occupied by valleys. The Fox 

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

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

 Laramie Group, whose actual thickness is not definitelj* ascertained, 

 consists also of gray and white sandstones, often iron-stained, contain- 

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

 It is OA'erlaid by an unconformable series of beds. The fauna of this 

 group is brackish, and, locally, even fresh water forms are found asso- 

 ciated with marine types. 



In the vallej^ 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 by the greater development of cla3'e3^ beds, and b}' the 

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

 of leaves and plant remains, especiall}' 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 Rocky 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 

 heav}^ 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 northeaste'rn wall of the Sulphur 

 Creek Valley-, shows a section of about 150 feet of beds, separated by 

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

 City, 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 

 remadvable 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.: Unto, Cor- 

 bula, Livinaea, Campeloma, Viviparics, etc. They evidently belong to 

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

 distance to the north by horizontal strata of the Vermilion creek 

 Eocene. |. ' 



