CRETACEOUS UPLIFT OF BITTER CREEK. 233 



spring, whose waters are very cold and clear, at the point of the blufife a 

 short distance to the east of the railroad-station, and in the ravine north- 

 west of that station there is a chalybeate spring which deposits salts of iron. 

 To the northward, toward the Leucite Hills, the surface of the bluffs is 

 plentifully covered by fragments of brown hematite of concretionary struct- 

 ure, which liave been weathered out from the sandstone, and whose quantity 

 renders it probable that careful search might reveal workable beds of iron- 

 ore in this region. The fossils found along this section of the Laramie beds 

 are principally confined to varieties of Ostrea, among which have been 

 determined 



Ostrea glabra. 



Ostrea Wyomingensis. 



Anomia gryphorhynchus. 



Cyrena cytheriformis. 

 Specimens of Ostrea were obtained as far east as the line of bluffs bor- 

 dering the dry water-course to the east of the Leucite Hills, which form the 

 limit of our exploration in that direction. In the bluffs to the south of the 

 sulphur spring, which have a height of about 350 feet, are exposed some 

 seven seams of coal, from 1 foot to 7 feet in thickness, interbedded with 

 beds of rusty sandstone from a few inches to 20 feet thick, and seams of 

 sandy and clayey shales. At the base is a massive white sandstone 50 feet 

 in thickness, overlaid by brown sandy shales containing a seam of coal 3 

 feet thick, which dips 7° to the eastward. The beds at the top have a dip 

 of less than 5°, a difference of angle too slight to enable one to determine 

 the exact point of non-conformity. A similar series of beds, in which the 

 same condition of angle exists, is found in the bluffs to the north of Point of 

 Rocks Station. 



To the west of Point of Rocks, the sandstones are generally more 

 heavily bedded, and contain a smaller proportion of shaly material, passing 

 by insensible gradations into the beds of the Fox Hill group. In the 

 sandstones of this latter group is found a thin bed of green compact 

 argillaceous rock, very close-grained, and resembling similar beds at this 

 horizon on the east side of the Platte at Fort Steele and in the Oyster Ridge. 

 It has the appearance of an indurated clay, but contains some little calca- 



