86 EEPOET UNITED STATES GEOLOGICAL SURVEY. 



feet. At tbat locality no springs were found, but tbe asphalt was hard, 

 brittle, had its cbaracteristio fracture, and upon subsequeut chemical 

 examination proved to be very pure. Springs of this mineral were dis- 

 covered by Mr. Chittenden near the head of Sweetwater Creek, where 

 the asphalt slowly oozed out of the sandstones similar to petroleum iu 

 certain regions. This, besides a few beds of limonite, was the only 

 deposit of economic value discovered during the season. 



A close estimate assigns to the upper sandstones a thickness of 1,100 

 to 1,200 feet. They are very uniform in their Hthological character, and 

 show but slight local disturbances. South of the White they reach up 

 to the highest points, forming the summits of peaks and the crests of 

 ridges. As we approach toward the divide between the White and 

 Grand we gradually pass upward through the series until about 20 miles 

 south of the river we once more reach the light-colored shales. These 

 continue eastward along the entire divide, and here as there show a sur- 

 prising constancy of dip as well as of lithological character. Although 

 125 miles distant from the most easterly exposure, where they were first 

 met with, they in no way show any appreciable change in general char- 

 acteristics. 



Throughout the district, the Green Eiver Group has been a very un- 

 satisfactory one, palsBontologically considered. The few fossils that 

 were found were plants and very poorly preserved. Silicified wood was 

 more abundant than any other petrifaction, but of no chronological 

 service. With fossils, the region would certainly have been one of very 

 great interest, although the stratigraphical relations are very simple, but 

 without fossils, without any structural features inviting study, and with 

 the ever-repeated occurrence of the same formations and groups, that 

 extensive Green River area afforded but poor results in return for the 

 ■work of a geologist. It is essential, of course, that its existence and 

 character in every respect should be determined, as it forms but a link 

 to the great chain which is gradually being completed. Thanks to cor- 

 relation with other determined horizons and typical lithological charac- 

 ter, the Green Eiver Group is readily recognized wherever met with, so 

 that the weight of uncertainty is not added to the disappointment 

 palseontologically. 



With this group we close the Tertiary formation of our district, as 

 none of its higher members are developed within its borders. Neither 

 are volcanic rocks occurring there, so that there remains for considera- 

 tion nothing but the recent deposits. 



ANCIENT GLACIERS. 



On the White Eiver drainage I have observed no evidence pointing 

 to the former existence of glaciers. The numerous caiions that we find 

 cut through the soft shales, marls, and sandstones, are formed so regu- 

 larly and agree so thoroughly with the pronounced stratigraphical con- 

 ditions, that we can scarcely admit of any other agency having shaped 

 them than water. Ascending any one of them toward the main divide, 

 we find that its upward slope is very even, its valley widening wherever 

 other creeks or streams enter, and its entire character in conformity 

 with the view regarding it as the result of the action of flowing water. 

 Primary conditions indicated partly by tbe present stratigraphical sys- 

 tem, have shaped the courses of the streams, but beyond that the results 

 we observe are mainly those produced by flowing water, together with 

 the never wanting atmospheric influences. 



In speaking of the Green Eiver Group, mention has been made of the 



