184 BULLETIN UNITED STATES GEOLOGICAL SUEVEY. 



or northwest at a moderate angle, and are much faulted, and yet at the 

 depth of 1,145 feet water flowed to the surface at the rate of 960 gallons 

 per hour, and at 26 feet above the surface at the rate of 570 gallons 

 per hour. While the drill passed through alternate layers of claySy 

 sands, and sandstones, as is usual iu the Laramie group, not less than 

 twenty or more seaQis of coal were fouud. From the position of the 

 strata above the surface at this point, as many more seams of coal must 

 exist above the top of the well in the Lignitic group before reaching the 

 base of the Green Eiver group. There must have been in former times 

 in this immediate region a large number of basins, for at no other point 

 can we detect any evidences of coal-seams. 



Although the record of these artesian borings, as preserved by the 

 railroad company, is very imperfect, it teaches an important lesson. I 

 deemed it best to preserve it, however imperfect, in this form, as proba- 

 bly the only information we shall ever have of the interior of the earth's 

 crust in this interesting region. That such an abundant supply of wa- 

 ter should have been obtaioed in several different localities in one of the 

 most arid portions of the West is a matter of the utmost practical impor- 

 tance. The annual rainfall in this district cannot be great — not more 

 than 12 or 15 inches. Accordiug to the observations made for the Smith- 

 sonian Institution for many years, the average annual rainfall at Fort 

 Bridger was only 6.12, while at Fort Laramie it was only 15.16. It could' 

 not be in excess of these figures at any of the intermediate points. It illus- 

 trates the value of the careful study of the position of the strata 

 in the arid places of the West, and the feasibility of rendering available 

 many millions of acres of land now lying useless. On the broad plains 

 east of the mountains, wells may be sank that will i^rove very useful for 

 pastoral purposes. 



The geology of this region is intensely interesting to geologists in- 

 another point of view, as showing, by the horizontality of the strata, the 

 apparent continuity of all the groups from the Cretaceous to the summit 

 of the Bridger group. The basin here is an extended one, and seems to 

 have been partially disconnected from the one west of Green River at 

 the present time ; but it undoubtedly was connected more or less from 

 near Rawlins Springs w^est to the Salt Lake Basin. In the Fourth An- 

 nual Report of the Exploration of the Survey in Wyoming, in 1870, 1 laid 

 much emphasis on the continuity of the Cretaceous and Tertiary beds. . 

 I also separated the Tertiary group into four series, in ascending order,, 

 as follows : — 



First series. — The coal strata, Lower Eocene, characterized by nu- 

 merous impressions of ' deciduous leaves, marme and fre ?h- water 1/oZ- 

 lusca. 



Second series. — Arenaceous, Upper Eocene, characterized by a pro- 

 fusion of fresh-water shells, as Unio, Goniobasis, Vivipanis, Lymncea, &c., , 

 a portion of these being casts. 



Third series. — Calcareous, Lower Miocene, containing the greatest 

 abundance of fresh-water shells, plants, fishes, &c. 



