526 REPORT UNITED STATES GEOLOGICAL SURVEY. 



These beds I Lave referred to the Green River Group. They are ex- 

 posed on the right bank of the Big Sandy, just above the mouth of the 

 Little Sandy. The course of the Big Sandy from this point to the Green 

 is south and southwest. It is in a low caiion without bottom-land or 

 groves, and is a shallow, rather sluggish stream, with a sandy bottom. 

 The rocks between the Big and Little Sandy are probably the same as 

 those given in the section above. Farther east, however, there are 

 higher beds which form high table-like buttes, resembling Pilot Butte, 

 that forms so prominent a landmark farther south. 



As we approach the mountains the valley of the Big Sandy improves 

 somewhat. It is wider and has better grass, but the surrounding country 

 is still sage-covered and monotonous. Variegated beds are seen resting 

 on the granite. The following is a section made between camps 4 and 5 : 



Section No. 2. 

 Base. 



1. Greenish gray and pinkish arenaceous bad-land beds 100 feet. 



2. Yellowish marls? and sands 200— 300 feet. 



3. White sandstones, shales and marls? with variegated argilla- 



ceous and arenaceous beds at the top. These were noted from 



a distance ? 



300-| 400+ feet. 



The strata incline about five degrees from the mountains and are prob- 

 ably of the Wahsatch Group, although the upper layers resemble the 

 lower beds of the Green Biver Group. These Wahsatch sands rest di- 

 rectly on granitic rocks, as already stated. The sources of the Big Sandy 

 are in the district surveyed by the Sweetwater division, and will be 

 found described in Dr. Endlich's report. 



New Forlc of Green Biver. — On the southwestern slopes of the Wind 

 River Mountains and in the adjacent foot-hills a number of beautiful 

 clear streams have their sources. These streams are all swift and ob- 

 structed by bowlders. Along their courses are abundant evidences of 

 glacial action, and long moraines extend from the mountains bordering 

 them as far as the edge of the basin. Glacial lakes also are numerous. 

 The creeks after emerging from the foot-hills form the New Fork of 

 Green Biver before joining the main stream. Our work during the 

 season did not extend into the foot-hills, so that the description of the 

 moraines and other glacial phenomena will have to be reserved for an- 

 other report. The region through which the branches of the New Fork 

 How may be described as a " bad -land" country. This is owing to the fact 

 that the rocks are mainly of Wahsatch age, especially those close to the 

 mountains. As we leave the hills, cappings of Green Biver shales ap- 

 pear. There is good grass throughout, and antelope were abundant 

 when we went through the country in June. Some of the valleys are 

 broad and well suited for agricultural purposes, were it not for the great 

 elevation. Willows are found along the streams, but timber is scarce 

 outside of the foot-hills. The stream bottoms are very marshy and the 

 creeks obstructed by beaver-dams. The northern rim of the Green 

 Biver Basin is beyond the limits of our district and will be the field for 

 investigation in 1878, and to the report for that year, when published, 

 the reader will have to refer for additional information in regard to the 

 sources of the New Fork of Green Biver. 



Green Biver. — Green Biver has a length of about 116 miles in our dis- 

 trict. In the northern portion of the basin beyond our district the rocks 

 are of Wahsatch age along the course of the river. Below the mouth 

 of Lead Creek, Green Biver beds are seen capping mesa-like buttes. As 



