GEOLOGICAL SURVEY OF THE TERRITORIES. 59 



barometer the highest point on the north side of the creek is 8,583 feet. 

 Our camp at the base near the creek is 7,615 feet, so that we have a ver-^ 

 tical thickness of the tertiary beds of over one thousand feet. On the 

 summit of the hill is a large accumulation of drift material, cemented with 

 a calcareous cement into a coarse conglomerate. It is composed mostly of 

 the sandstones, quartzites, aud carboniferous limestones from the Uinta 

 Mountains. These conglomerates are two hundred to two hundred and 

 fifty feet in thickness, and are weathered into columns, sharp-pointed 

 peaks, domes, &c, much like the conglomerates in Echo Caiiou. 



The summit of this high wall is a sort of table land covered with a 

 deposit of fine reddish sand, plainly derived by erosion from the sand- 

 stones and quartzites of the Uintas. The surface is covered with grass, 

 and slopes gently northward for several miles. From this high point I 

 could comprehend to some extent the tremendous erosive forces that 

 had been in operation here at a comparatively modern date. All the 

 tertiary beds probably once extended uninterruptedly across the val- 

 ley of Henry's Fork and jutted up against the sides of the Uinta range, 

 and this immense deposit of conglomerate which caps the summit 

 passed across and connected with the drift materials high up on the 

 radiating ridges. It is an interesting fact that if we make a careful 

 examination of the country we shall always find some remnants of the 

 formations that may have existed, however great the erosion may have 

 been. They seem to be left as monuments to aid us in reconstructing 

 the surface as it really existed at different periods of the past; and this 

 fact adds much to the charm of the study of the geology of the West. 

 There is a slight inclination of the beds, which shows that they partook 

 somewhat of the later movements of the mountains. As we descend, 

 following the stream, we pass below the leaden-gray indurated clays of 

 the Bridger group into a series of lighter-colored marls, with layers of 

 laminated chalky limestone. These marls and limestones are somewhat 

 arenaceous at first, but the sand diminishes and the lime increases in 

 the descent. All the beds assume a lighter and more cheerful color, 

 although there is some variety from rusty yellow to white. Henry's 

 Fork flows about fifteen miles from its source nearly north, when it 

 bends around a little north of east for about forty-five miles to its en- 

 trance into Green River. Most of the way it passes through a narrow 

 valley about one-quarter of a mile wide, with abrupt, wall-like terraces 

 on either side. These vary from eighty to one hundred and fifty feet 

 in height. The bottom itself is quite pretty, covered with a thick 

 growth of grass and large bitter cottonwoods. The grass in some places 

 is six feet high and very thick. Hundreds of tons of hay are procured 

 from this valley every season, and it is a favorite resort for herds of 

 cattle and sheep in the autumn and winter. The soil is as rich as any 

 in the West, being formed of the sands and clays of the Bridger group, 

 Avith the calcareous materials of the Green River beds, as well as con- 

 tributions from the limestones and quartzites of the Uintas. The mix- 

 ture seems to be suitable for the production of a luxuriant vegetation 

 under favorable circumstances. 



At our camp, October 4th, the lower miocene beds rise up on the north 

 side of the creek to a height of four hundred to five hundred feet. Near 

 tne base are layers of thinly-laminated slate, limestone, and some beds 

 oi cherty limestones with plants. There are also several thin seams of 

 earthy lignite. There are several thin layers, especially near the lignite 

 seams, which vary from an inch to six inches in thickness, composed 

 mostly of small fresh- water shells, Melanias and Unios. These layers of 

 shells continue nearly to the mouth of Henry's Fork, and masses of them 



