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Show 70BT BBIDGER. 75 rocks and some sandstones, the former greatly predominating. In some places, layers of blue and red clay, « f considerable thickness, were observed, and also gray argillaceous limestone; but owing to the surface of the rocks being covered by the clay detritus, no complete sections of them were obtained) nor were any fossils found in them. Farther on, upon Black's Fork, a ridge was crossed in which the different layers of the rocks were quite- apparent. Here two strata of coarse reddish sandstone, which disintegrated but slowly, were prominent. They were separated by layers of limestone, shales, and clay. The shales were so nearly horizontal that no dip could be ascertained. Following the valley of Black's Fork, we passed, in the afternoon, strata of green and whjte sandstone, whitish shales, and clay, but too much decomposed to afford us any fossUs. In the valley were found some blocks of limestone, wholly made up of the debris of shells. The valley of Black's Fork, in the vicinity of Bridger's Fort, is three or four miles broad, and many of the numerous little branches into which the stream is divided are handsomely fringed with thickets of cotton- wood. The soil is composed of the detritus of the surrounding rocks, and huge blooks of metamorphic rock, and some trap and serpentine, are found upon the surface. At the fort we were shown a piece of rock, evidently volcanic, in the cells of which were contained some particles of gold. It was stated that it had been, found in the bed of Black's Fork in the vicinity. If so, it must have been washed down from the Uintah chain of mountains, a lofty range to the south, in which the stream headss These mountains were at this time covered with snow for a considerable distance from their summits; but of their lithological formation no opinion eould be formed, as their g? e » t distance precluded all opportunity of examining them. The strata of the hills around the fort were nearly horizontal, and consisted of gray limestone, clayey and slaty shales, and sandstones.' Some few miles up the stream) Sections of these rocks were found, from which some fossils were obtained. In the beds of, the stream were found rounded rocks, composed principally of metamorphic sandstone, and some marble* The same rocks were seen in horizontal strata on the hills* From Fort Bridger there are now two routes as far as the Humboldt or Mary's River, where they ; again unite. The old road strikes Bear River, follows down its valley by the Soda Springs to Fort Hall, whence it pursues a south- westerly course to the Humboldt. By this route a northing of nearly two degrees is made, |
