peale.] DESCRIPTIVE GEOLOGY GREEN RIVER BASIN. 531 



end of the mountain, but as the region on Labarge at the south end of 

 Thompson Plateau was not visited, I cannot be certain of the exact 

 relations. This is an interesting region and will repay the geologist who 

 may be able to devote time to its detailed study and investigation. 

 From Feather Creek south to Labarge Creek the surface rocks are 

 the Wahsatch, with the exception of the mesa on the south side of the 

 former creek. The Wahsatch variegated beds also form buttes and 

 mesas, bright red colors predominating. As we approach Labarge 

 Creek the level becomes lower and more uniform. Here there is a dip 

 to the southward and also to the eastward, so that on the west side 

 of the Green below Labarge Creek, the bluffs are composed entirely 

 of Green Eiver beds. On the east, however, a tongue of Wahsatch 

 extends a short distance below the mouth of the creek. The sandstones, 

 however, are the most promiuent rock and are well exposed in the bluff 

 on the west. In the lower portion of these sandstones above the mouth 

 of the Labarge, on the east side of the Green, as well as on Fontenelle 

 Creek, Professor Cope, in 1873, found " numerous remains of fishes simi- 

 lar to those of Green Eiver City, with insects and their larvas, shells 

 like Pupa and Cyrena, and millions of Cypris." * The Green was at its 

 highest stage when we followed it, and it was found to be impossible 

 to cross to the east side. The country between the Labarge and Fon- 

 tenelle is pleateau like, with a gentle inclination eastward as we ap- 

 proach Meridian Eidge. Green Eiver shales and sandstones prevail, 

 with, perhaps, Wahsatch near the ridge. The latter between the two 

 streams was not visited, and therefore nothing definite can be predicated 

 in regard to it, but it is probably composed of Jurassic and Carboniferous 

 rocks. On the Green the sandstones of the Green Elver Group have 

 a thickness of about 500 feet. East of the Fontenelle this thickness 

 appears somewhat greater, shales forming the upper part of the beds. 

 Ascending Fontenelle Creek the sandstones descend somewhat, and shaly 

 beds show above. As we approach Meridian Eidge the beds rise gently 

 and the variegated Wahsatch beds outcrop beneath, resting on the east- 

 ern slopes of the ridge. At the base of the latter beds, near the canon, 

 is a very coarse conglomerate, and above are bright red, loosely aggre- 

 gated sands. The shales and sands of the Green Eiver Group above 

 the latter are much thinner than on the Green, as we would naturally 

 expect. I searched for fossil remains in these layers, but without suc- 

 cess. 



Labarge Creel: — The upper portion of this stream is mainly in Creta- 

 ceous rocks that continue northward from the Fontenelle Hogbacks and 

 will be described hereafter. It enters the basin through the canon south 

 of Thompson Plateau, and from this point its course is about east, while 

 above the canon it is south. The geology of this portion has already been 

 given. It is a considerable stream, and enters the Green in several 

 branches that spread over a wide meadow. 



Fontenelle Creek was named after one of the early fur traders. It has 

 its sources in the AbsarokaEidges opposite those of Ham's Fork. Thence 

 the streams flow eastward and southward across and through the Fon- 

 tenelle Hogbacks until all unite in one main stream at the Meridian 

 Eidge, through which a caiion some 900 feet deep is cut to the basin. 

 Thence he stream flows eastward through a plateau-like region to the 

 Green. This plateau of Green Eiver beds extends southward beyond 

 Slate Creek and disappears beneath the Bridger Group north of Ham's 

 Fork. 



Slate Creelc rises in the eastern and western slopes of the south end of 



*Page 439, Report U. S. Gcol. Survey for 1873, 1874. 



