80 GEOLOGICAL SUEVEY OF THE TERKITOEIES. 



color — color sometimes gray — 2.80. As a fuel for domestic purposes, I 

 am convinced that this coal will rank next to anthracite and prove supe- 

 rior to the ordinary bituminous coals. 



It is as neat as anthracite, leaving no stain on the fingers. It produces no offen- 

 sive gas or odor, and is thus superior in a sanitary point of view, and when brought 

 into general use it will be a great favorite for culinary purposes. It contains no dis- 

 tinctive elements, leaves very little ash, no clinkers, and produces no more erosive 

 eifects on stoves, grates, or steam-boilers, than dry wood. If exposed in the open air 

 it is apt to crumble, but if protected it receives no special injury. Dr. Torrey thinks 

 there is no reason why it should not "be eminently useful for generating steam and for 

 smelting ores.* 



In the Laramie Plains, along the line of the Union Pacific Eailroad, 

 extensive beds of this coal have been opened, and the coal is used for 

 generating steam and for fuel on the cars. It cannot be long before it 

 will come into general use throughout the West. 



August 15. — Left Cheyenne City with Dr. Curtin, an assistant on the 

 survey, and Mr. Whitehead, a citizen of Cheyenne City, for the purpose 

 of exploring the Chugwater Valley to its head. For the first 20 miles 

 we passed over the light-colored marls and sands of the White Eiver Ter- 

 tiary. As we approached the foot of the mountains we came into a 

 beautiful valley, ranging from three to ten miles in width, looking as 

 though it had been scooped out, as it were, during the glacial period by 

 forces from the mountain-side. 



All over this country are marked proofs of a powerful erosion at the 

 .close of the Drift period, which gave to the surface of the country its 

 present configuration. There are also terraces along the base of the 

 mountains, as well as along the streams, and the nearer we approach 

 the mountain-slopes the more conspicuous the terraces become. 



We camped, the night of the 15th, on Horse Creek, a branch of the 

 North Platte. This valley can hardly be surpassed for grazing pur- 

 poses. The water is excellent and the grass good. Near the point where 

 the creek issues from the foot-hills of the Laramie range, ther^ is a series 

 of upheaved ridges, with a strike nearly east and west, the beds inclin- 

 ing from 50° to 70°. The series of strata seem to be nearly as complete 

 as those observed southward toward Denver. The red arenaceous beds 

 are well shown, but no gypsum was seen. 



In the valley of the Chugwater, near the point where the branches 

 issue from the mountains, the unchanged rocks are elevated at various 

 angles, and, by their great variety of colors, give a most picturesque 

 appearance to the scenery. 



In clearing away from the syenite nucleus, we have here, first, the red 

 arenaceous beds, 1,000 to 1,500 feet in thickness; then 600 to 800 feet of 

 variegated marls and clays, with layers of sandstones, all destitute of 

 fossils or any evidence of their age. These beds incline southwest at 

 various angles, 19°, 11°, 6°, &c. Then the Cretaceous beds are quite 

 well represented. From No. 5 I gathered Baculitus ovatus and a species 

 of Jnoceramus. 



Upon the Cretaceous beds, but not conforming to them, rest the White 

 Eiver Tertiary beds,, inclining at a small angle, as if they had partaken 

 of the latest upward movement of the mountain-ranges. 



The central portions of the mountains are composed of syenite mostly. 

 The outer beds are rotten syenite of a dull-gray color, disintegrating to 

 such an extent that the surface is covered with a thick deposit of crys- 

 tals of feldspar. As we approach the dividing ridge the beds of syenite 

 become more compact and durable. Now and then we find thin beds of 



* Silliman's Journal, March, 1868. 



