64 GEOLOGICAL SUEVEY OF THE TERRITORIES. 



is about east to the lower end of Brown's Hole, where it seems to bend off 

 south of east. After crossing this high triassic ridge our course was neary 

 east, parallel with the river on the north side, thus passing diagonally 

 across the different formations. We soon have on our left hand a frag- 

 ment of the purplish sandstone, and outside of that a high ridge of 

 carboniferous limestones, rising six hundred feet, and inclining 45°, 

 with a trend about southwest and northeast. On our right were the 

 ridges of the purplish sandstones and quartzites, rising step by step to 

 the axis of the mountains, where the strata appear nearly horizontal, as 

 at the source of Henry's Fork. Stunted cedars are quite thick upon 

 the mountain sides, and for the first time this season we met with the 

 "Piilon," (Pintis edulis,) or nut-pine, so common in New Mexico. The 

 trail was a rugged one, leading over broken rocks, and up and down 

 precipitous hills. 



Brown's Hole is an expansion of the valley of Green Eiver, and is 

 about five miles wide and thirty in length. Just before reaching the main 

 valley there is a small expansion called Little Brown's Hole. These are 

 names given to these localities by the old trappers, forty years ago or 

 more. Far north, in the mountains at the sources of the Columbia, are 

 beautiful valleys of a similar character, called Pierre's Hole, Jackson's 

 Hole, &c. These were all favorite wintering places for the trappers. 

 But little snow fall in them, and they are so surrounded by high moun- 

 tains that the bleak winds of winter can not reach them. Brown's Hole 

 has been a favorite locality for wintering stock for many years, and the 

 day we visited it, twenty-two hundred head of Texas cattle were driven 

 into it from the east, to remain during the winter, and destined for the 

 California market in the spring. It is covered with wild sage and cheno- 

 podiaceous shrubs, with scattered bunch-grass. A small number of 

 cattle or horses could find abundant food for winter, but so large a 

 number as were in it at the time we visited it must consume all the 

 grass in a few weeks. The strata of red quartzite are distinctly shown 

 on each side of the valley. It would appear that there had been 

 originally a sort of monoclinal opening, the beds on the north side dip- 

 ping northwest 20° to 30°. They present their upturned edges, there- 

 fore, to the valley, and here and there beds of gneiss and white quartz 

 have been thrust up, sometimes to a great height, so that the sides of 

 the mountains have a somewhat variegated appearance. At first glance 

 I supposed some of the modern tertiary beds had been lifted high on 

 the sides. On the south side of the valley the quartzites dip gently 

 down to the eastern end of the wall, and apparently pass under the modern 

 tertiary beds. In the process of erosion the waters have cut diagonally 

 across the sides of the quartzite beds, so that they appear somewhat like 

 the opposite side of the anticlinal ; but I am convinced that it is an 

 inner ridge, inclining originally in the same direction, and extended over 

 a portion of the south side of the valley. 



The gorge from which the Green Biver issues, near the mouth of Ver- 

 million Creek, is very beautiful. The waters have cut a channel directly 

 through the rocks, showing the layers most perfectly on each side, in- 

 clining at a moderate angle. Mr. Jackson was very fortunate in securing 

 an excellent photograph of this caiion, which will express its geological 

 characters perfectly. In this valley there is an extensive modern de- 

 posit, which I suppose to be of pliocene age. It is composed of beds of 

 fine sand or very friable sandstone, light gray, yellowish gray, with 

 brown sandstone in thin lamina?, &c. The whole deposit seems to be 

 sand, with some mixture of clay, and weathering in the usual style of 

 these deposits into rounded hills with deeply and regularly-furrowed 



