BIG SANDY — COLORADO OR GREEN RIVER. 73 



obliged to wedge up the wheel as Avell as we could, and to sink it 

 in the river during the night, to swell the wood. 



The bluffs on Big Sandy presented several sections. The 

 strata consisted of thin layers of clayey shales, argillaceous gray 

 limestones, and of crystallized sulphate of lime. These strata 

 were seldom more than two or three inches in thickness, the 

 layers of gypsum being about half an inch. There were also thin 

 laminae of dark slaty shales above the gray limestone. Kemains 

 of plants were found, and also some imperfect shells. Near the 

 junction of Big Sandy with Green River some large nodules of 

 ferruginous sandstone were observed, and near them the remains 

 of trees of a large size. The dip was about 5°, a little to the west 

 of south. Upon Green River we came upon a layer of brownish 

 clay, of considerable thickness; and from the appearance of the 

 hills on our right, it is probable that they are formed by the 

 weathering of this bed of clay. Green River,. or the Colorado of 

 the Gulf of California, is here a fine, bold, clear stream, discharg- 

 ing a large quantity of water. In its bed are found rounded 

 stones, consisting principally of detritus of primary rocks. Day's 

 march, only thirteen miles. 



Friday, August 10. — After travelling about four miles, the road 

 leaves Green River and crosses over a ridge dividing it from 

 Black's Fork, one of its tributaries, upon the left bank of which 

 we encamped, with abundance of grass, and wood obtained from 

 the willows which here fringed its banks. The Uintah mountains 

 were distinctly seen far to the south, their sides glittering with 

 snow in the rays of the setting sun. 



In a ravine of the western bluff of Green River valley, the rocks 

 were partially exposed, particularly some strata of hard white 

 sandstone. They consisted of sandstone in laminae, about fifteen 

 inches thick, and layers of argillaceous shales, and argillaceous 

 limestone, made up principally of shells. There were evidently, 

 also, some strata of conglomerate, formed chiefly of serpentine, 

 sienite, and trap. Among the rounded pebbles found near the 

 top of the ravine was one of dark foetid limestone, partially con- 

 verted into marble, and precisely similar to the metamorphic lime- 

 stone observed flanking the granite chain in the vicinity of the 

 South Pass. A specimen of fossil wood was also found, which ap- 

 peared to have been partially converted into lignite. The strata 

 were, as far as could be judged, horizontal, and a section on the 

 opposite side of the valley showed the same sandstone maintaining 



