GEOLOGICAL SUEVEY OF THE TERRITORIES. 73 



occurs near the base of the series, made up of casts of Unios, Lym-neas, 

 &c. 



Between LaClede and Barrel Springs the strata are very nearly hori- 

 zontal. The surface is less rugged ; still to the south of the road are high, 

 rather abrupt ridges, and in the distance are quite pointed ridges three 

 hundred feet high, composed of the somber, hard, indurated, rusty 

 arenaceous clays which characterize the Bridger group. Indeed, from its 

 form and style of weathering, and the color of its sediments, it could not 

 be distinguished from the high ridges of Bridger beds west of our road 

 from Henry's Fork to Green Biver Station. Although I have hitherto 

 regarded the group of beds which I have denominated the " Washakie 

 group," as separated from those of Greeen Elver and to the westward, 

 yet I am now inclined to believe that the upper series is either an exten- 

 sion eastward of the Bridger group or synchronous with it. Fragments 

 of turtles and other vertebrate remains are not uncommon. 



Near Barrel Springs a very good section of the laminated, chalky 

 clays is exposed in the valley of the Muddy ; seams of shells as Unio tel- 

 linoides, Goniobasis tenera, G. nodulifera, and G. Carteri, four inches thick, 

 occur above and below thin layers of rotten vegetable matter. These shells 

 occur through fifty to one hundred feet of these chalky beds. Bemains 

 of turtles, also vertebrae of fishes and reptiles, are found ; a few obscure 

 plants, like blades of grass, stems of rushes, &c„ occur in the clays ; still 

 higher on the tops of the hills that border the stream, are some thin, 

 chalky clays, crowded full of plants, as ferns, rushes, grasses, palms, &c, 

 finely preserved. Fragments of palm-wood and those of deciduous trees 

 are scattered over the surface in great profusion. I think I have never 

 seen vegetable remains more abundant or more easily obtained in any 

 |3ortion of the West than at this locality. There was about two feet of 

 strata composed of them, and they split into very thin regular layers, 

 as light as dry vegetable matter could be, and each side of the thin 

 layers was covered with beautiful impressions of leaves in a remarkably 

 fine state of preservation. Upon these weathered hills were literally 

 bushels of very pretty Goniobasis and Unios, which onecould gather to his 

 entire satisfaction. I regretted very much that my party could not 

 remain a day in this interesting region ; but the almost entire absence 

 of grass and the alkaline water compelled us to hasten on with our half- 

 starved animals. 



From Barrel Springs we descend geologically, the dip of the rocks being 

 reversed, and the same beds rise to view that we saw in traveling east- 

 ward from Black Buttes. As we descend into the valley toward Duck 

 Lake, the pinkish bed makes its ai3pearance, and on the left of the road is 

 an isolated mass of sandstone, about twenty feet cube, which forms a sort 

 of landmark. Although this red layer is a conspicuous feature in this 

 region for miles along the valley of the Muddy, yet this isolated mass is 

 the only example of hardened rock connected with the red band in this 

 region. There must have been some local cause originally for the greater 

 tenacity of the cementing material in this restricted locality. 



The water divide of this region is undoubtedly Bridger's Pass, but the 

 geological divide I regard as located between La Olede and Dug Spring 

 Station. Here the strata are nearly horizontal, or from what might be 

 called a synclinal. Along the Union Pacific Bailroad at Dodge's Sum- 

 mit, the water and geological divide are identical. The strata west of 

 this divide incline slightly northeast, and on the east side southwest. 

 As I have already stated in a preceding chapter in describing the tertiary 

 formation from Bridger to Green Biver, they may be separated provision- 

 ally into four series. 



