GEOLOGICAL SUEVEY OF THE TERRITORIES. 79 



a more cheerful aspect; the water is as pure as crystal, and grass covers 

 the surface very thickly. Dense groves of aspen are abundant among 

 the foot-hills, and the little streams are all fringed with timber. From 

 the summit of a high hill on the west side of Bock Creek we have the 

 finest view of the Laramie Plains I have ever seen. We reached Book 

 Creek on one of those clear days after a rain storm, when the sun shines 

 out with that wonderful brightness which is peculiar to this country. 

 The entire area of the Laramie Plains was spread out before us like a pan- 

 orama. The Laramie range forms a perfect wall on the east and north 

 side, and marks the horizon from the east, around to northwest, and 

 apparently dies out. To the north, Laramie Peak is as plainly visible as 

 it is from Fort Laramie on the opposite side of the range, and rises high 

 above any other portion. The entire surface of the plains east of the 

 Medicine Bow, encircled by the main Bocky Mountains on the south, 

 and the Laramie range on the east and north, has been smoothed off by 

 denudation and grassed over, so that it forms one vast pasture-ground 

 about sixty miles in extent from east to west, and nearly the same dis- 

 tance from north to south. From the mountains on the south side de- 

 scend, parallel with the valleys of the streams, beautiful benches, 

 with smooth, table-like summits; while forming a portion of the foot-hills 

 of the mountains are numerous rounded hills, grassed over, and paved 

 on the tops and south side with the different kinds of rocks which con- 

 stitute the nucleus of the mountain range, as garnetiferous gneiss, 

 quartzites of all colors, red and gray granites, with quartz, trap rocks 

 of various textures, fibrous gneiss, &c. These rocks are quite well worn, 

 and they seem to lie on the summits of the hills as they were dropped 

 by an iceberg, and present the appearance of leaning to the northward 

 as if on the move. The shape of the hill and the position of the stray 

 masses impresses one with the thought that they were only delayed for 

 a time on their way from the mountains to the plains. These examples 

 of local drift or erratic blocks are very common and well defined in the 

 Laramie Plains. Indeed, I have never seen any evidences in the Bocky 

 Mountain region of any foreign drift. All the superficial deposits belong- 

 ing to the quarternary period, seem to me to be local in their origin. 



Bock Creek Valley is very beautiful and picturesque. The stream 

 emerges from a very narrow gorge in the mountains, which is covered 

 with a dense growth of pines. As we look down the stream from the 

 gorge the valley seems to expand to two or three miles in width, and there 

 are three belts of trees winding through it as if there were as many 

 separate streams. The other portions of the valley are like a meadow. 

 About half a mile, along the old stage road, on Bock Creek, the meta- 

 morphic rocks are well shown, holding a nearly vertical position. There 

 are gray and reddish feldspar beds, inclining'eo . There are also beds 

 of what appears to be ancient trap. These ridges form steps which lead 

 up to the Snowy range. No sedimentary rocks older than the creta- 

 ceous are seen in the valley of Bock Creek. The valley is literally cov- 

 ered with water-worn boulders of all kinds, mostly metamorphic, and 

 hence its name. These boulders diminish in size as we descend the 

 creek until they nearly or quite disappear. All the hills on either side 

 show accumulations of these worn rocks on the side facing the moun- 

 tains. On the east side of Bock Creek the yellow sandstone which un- 

 derlies the long bench is undoubtedly cretaceous No. 5, and contains a 

 few fossils, among which are the usual Inoceramas and Faculties ovatus. 



On the east side of Cooper's Creek there is a long, high ridfe, with its 

 abrupt side toward the mountains, and covered thickly with the rounded 

 boulders — a marked illustration of the direction from which the bould- 



