BEAR EIVEK CITY CRETACEOUS. 327 



Fox Hill group to the west of the ridge already mentioned, since the Ostrea 

 solenisciis is also found in the vertical sandstones to the east of the clays 

 and shales. At Bear River City, the hills to the north are formed of heavy 

 standstone beds, containing several coal seams standing perpendicularly, 

 and in some cases having a slight inclination to the westward. They con- 

 tain plentiful casts of Inoceramus prohlematicus, and an Inoceramus dimidkis 

 has also been found in this vicinity. Both these forms are characteristic of 

 the Colorado Cretaceous, so that, though lithological evidence would place 

 the dividing line between Fox Hill and Colorado a little east of Bear River 

 City, on palseontological grounds the sandstones and included coal seams 

 at that point should be included in the latter group. West of Bear River 

 City, along the face of the hills north of Sulphur Creek, are exposed out- 

 crops of from 5,000 to 7,000 feet of strata, standing at angles of 85° to 90° 

 west, and striking north 30° to 45° east, consisting of heavy white sand- 

 stones with conglomerate beds, and passing to the westward into reddish- 

 brown sandstones with frequent clayey seams, which would include the 

 entire Fox Hill and part of the Laramie Cretaceous. 



The structure of the section thus exposed, from Aspen westward, would 

 be first a broad synclinal, whose western member turns up abruptly at 80° 

 to 90°; then a sharp anticlinal in the Colorado beds, both of whose mem- 

 bers stand quite vertical, and whose western member includes the Colorado, 

 Fox Hill, and Laramie Cretaceous. From the prevalence of western dips 

 in this section, one might perhaps be led to suppose that the Colorado beds, 

 west of the sandstone ridge at the bend of Sulphur Creek, were simply 

 faulted up; but their thickness exposed, which cannot be less than 5,000 to 

 6,000 feet, makes a reduplication of the beds by folding necessary, while 

 the structure, shown on the same line of strike at the head of the Little 

 Muddy, renders it probable that the system of sharp anticlinal and synclinal 

 folds shown there finds its continuation on this side of the divide. 



About two miles west of Bear River City, a railroad-cut through a low 

 ridge running out from the high ground, already described as forming the 

 northeastern wall of the Sulphur Creek Valley, shows a section of about 150 

 feet of beds, quite distinct lithologically as well as palseontologically from 

 any observed, though resembling in some respects those on the Little Snake 



