530 REPORT UNITED STATES GEOLOGICAL SURVEY. 



lias been extensive, the Wyoming Range probably furnishing a "rent 

 part of the water causing it. Farther south, where the mountains bave 

 diminished to hills, the covering of Green River beds still remains. 

 Another reason is to be found in the fact that the greater elevation of 

 the beds on the northern portion of the basin has exposed them more to 

 the eroding - influences. 



From the junction of its forming branches Piney Creek flows almost 

 due east to the Green. It splits into several streams near the river. 

 The valley in which this creek and the Bitterroot flow side by side is 

 one of the best along the Green. Its elevation is about 6,800 feet, being 

 about 350 feet lower than the valley at the mouth of Horse Creek. Sev- 

 eral ranches have been started on the Pineys, as the branching mouth 

 of the Piney has been called. The old Lander cut-off road, which crosses 

 Green River above the mouth of the New Fork, crosses the country 

 between White Clay and Piney Creeks, and follows up the latter to 

 Thompson's Pass, from which it crosses to the head of Labarge Creek, 

 and thence to the head of one of the branches of Smith's Fork of Bear 

 River. 



Feather Creek. — Nine or ten miles below the mouth of the Piney, a 

 small, dry creek bed is crossed. Followed up, this creek is seen to spread 

 out feather-like on the slopes reaching eastward from Thompson Plateau. 

 Hence its name. The upper branches contain water which extends some 

 distance down the main creek. It has two main stems between which 

 is a V-shaped mesa of Green River beds. West of this mesa is a hill 

 of Carboniferous rocks surrounded by Wahsatch beds. This Carbonif- 

 erous island was not visited, but is doubtless similar to the one just 

 south of it known as Labarge Mountain. On the latter two stations 

 were made, viz, Nos. 19 and 20. These stations are located on a long hill 

 or mountain that forms a rather prominent landmark as we come down 

 the valley of the Green. It is about 5 miles long, and composed of Car- 

 boniferous limestones, dipping about 25° to north 73° west. The trend 

 of the mountain is about south 17° west. Station 19 was located at the 

 north end, and Station 20 at the south end. The outcrop of limestones 

 to the east of Station 19 is about 400 or 450 feet in thickness. The 

 valley between the station, and the mesa is about 1,200 feet to 1,400 

 feet below the stations and 000 to 800 feet below the mesa top. The 

 mesa just referred to is a mesa extending along the south side of 

 Feather Creek toward Green River. This mesa is capped with the 

 lower part (?) of the Green River Group, and slopes at an angle of 

 5° to 10° from Labarge Mountain toward Green River. The gap 

 between the mountain and the mesa was not visited from want of time, 

 but should be examined before the region can be fully described. 

 It is probably filled with Wahsatch beds, judging from what could be 

 seen from the summit of the mountain. If the latter is the remnant 

 (western side) of an anticlinal, evidences of the eastern side might pos- 

 sibly be found appearing in places above the Wahsatch beds. As it 

 shows now, it is a monoclinal ridge facing the east. A few indistinct 

 crinoidal markings were observed on Station 19, and on Station 20 some 

 indistinct corals, Productiis, and a poor Strophomena. East of Station 20 

 near the foot of the mountain is an outcrop of sandstones and quartzites, 

 but their relation to the limestones was not determined. West of the 

 mountain is the main stream of Feather Creek, which flows around the 

 north end of the mountain. From the creek, long slopes rise gradually 

 to the Thompson Plateau. These slopes are smooth, with reddish expo- 

 sures, which I have taken to be outcrops of Wahsatch and have so 

 colored on the inap. The beds appear to curve around the southern 



