HENRY'S FORK BASIN. 263 



thickness and lithological character with that found on the Flaming Gorge 

 cliffs. He found a thickness of about 300 to 400 feet in the cliifs overlook- 

 ing Sheep Creek, where the angle of dip was 25° northwest, consisting 

 largely of sandy and argillaceous shales and sandstones, which would prob- 

 ably underlie the beds mentioned above, and below them limestones, from 

 which he obtained a numerous collection of fossils comprising the following 

 genera: 



Trigonia (two species). 



Camptonedes. 



Ostrea (small). 



Volsella. 



Neritella (like N. Nehrascensis). 



CliemniUia. 

 . Pentacrinus asteriscus. 

 He also notes in the shales of the lower portion beds of gypsum from 

 1 to 6 feet in thickness. Below the Jurassic beds are the massive buff sand- 

 stones of the Triassic formation, underlaid in turn by the red sandstones of 

 this formation. 



This remarkable curved ridge, which has been called Flaming Gorge 

 Eidge, presents a great variety of strikes and dips in the strata of which 

 it is formed, the former varying from east 50° north a little east of the 

 junction of Kingfisher and Sheep Creeks, to east 20° (and possibly even 

 more) south at Green River, while the dips vary from 25°, to 45° and 

 60° at Camp Stevenson, and 90° at Green River, and, in this variety of dips 

 and strikes in a perfectly conformable series of beds, illustrates how easily 

 apparent non-conformities may be caused by such secondary lateral flexures 

 along the flanks of a great anticlinal fold. 



In the sharp re-entering curve, at the point where Green River cuts 

 this ridge, the beds are almost inverted by the suddenness of the flexure, 

 and may doubtless have suffered a lateral dislocation, as may be seen in 

 the view shown in Plate VII, which, looking westward, shows a natural 

 section of the ridge. The perpendicular cliffs, here about 1,200 feet in 

 height, are formed of the Triassic sandstones, having at their base an unde- 

 termined thickness of clay beds, while the extreme point on the north and 



