94 GEOLOGICAL SURVEY OF THE TERRITORIES. 



stretclies far westward to Bitter Creek and Green Eiver, with very little 

 grass or water for the traveler. 



From our camp of September 4, on Pass Creek, we traveled nearly 

 north or northwest to the railroad. The long ridges seemed to dip away 

 from the open plain. The trend of alone ridge of greenstone was nearly 

 east and west. 



The main trend of these ridges is a little north of west, and the dip, 

 of course, east of north. 



Looking at the east or southeast side of the plain the mountains seem 

 to rise in long ridges, step by step, and to trend about northeast and 

 southwest, the southwest end sloping gently down into the plain. When 

 we look at details it is almost impossible to discover any system in the 

 trend or inclination of the beds, except in a general way. The aggre- 

 gate of the mountain-ranges will be found to have a definite trend, as 

 is shown on our topographical maps. The general trend of mountain- 

 chains is nearly northwest and southeast ; but if we examine the smaller 

 ridges in detail, we shall find that the forces operated from beneath the 

 crust in almost every direction. 



It becomes, therefore, quite important to describe the geology of every 

 locality with minuteness, even at the risk of repetition and tediousness. 

 From all these detailed descriptions may be derived some important 

 generalizations. 



The rusty calcareous sandstones which compose the inner lower ridges 

 facing the plain are undoubtedly Upper Cretaceous, and incline 30° to 

 45°. These rusty sandstones form a belt about one and a half mile 

 wide, the intercalated beds being composed of loose yellow arenaceous 

 material, which is covered with grass, the harder layers merely project- 

 ing above the surface in patches here and there. Very few fossils can 

 be detected in these beds. I found an Iiioceramus, a Baculite, and a 

 species of Ostrea, sufficient to indicate their age. One of these ridges 

 of Cretaceous sandstone is very conspicuous, and forms a long wall on 

 the north side of the i)lains, extending about five miles, and then dies 

 out. 



We have here also several synclinal and anticlinal valleys, trending 

 nearly east and west, but there is an anticlinal valley which commences 

 at the foot of Elk Mountain, and strikes northwestward to the Sweet- 

 water Mountains. This anticlinal valley may be seen along the Union 

 Pacific Eailroad as far as Rawling's Springs Station, when it begins to 

 fade out in that direction. It forms the chain of connection, however, 

 of the elevating forces which raised those mountain-ranges, linking the 

 main ranges south of the plains with those of the north. 



Having given in the preceding pages the details of the geological 

 character of the country along the line of the overland stage-route, as 

 far west as Green River, we will return to Fort Sanders, and follow the 

 line of the Union Pacific Eailroad to the same point. And I would here 

 remark that so little is known even of the outline of the great formations 

 along this route, that any information, however brief, will be of interest. 



The facilities afforded by this road are bringing into this region emi- 

 nent men from all portions of the world, and the singular unique geolog- 

 ical and geographical features which meet the eye on every side excite 

 marked attention and inquiry. 



From Laramie City to Cooper's Lalie Station, a distance of 25.6 miles, 

 there is a good degree of uniformity in the character of the country as 

 we proceed westward. 



On our right the Laramie range appears like a wall bending outward 

 to the northwest and west, and finally ceases to be seen. 



