130 GEOLOGICAL SURVEY OF THE TEKRITORIES. 



18. bandstonc, dip. 11°. This sandstone Las a reddish tinge, and is. 

 less massive than 14. 

 17. Drab clay. ^ 



10. Coal, (No. 4.) V 20 feet, obscure 

 15. Drab clay. ) 



14. Sandstone, massive, GO feet. 

 13. Drab clay. 

 12. Sandstone. 



11. Drab clay. 

 10. Coal, (No. 3.) 



0. Drab clay. 



8. Sandstone, 25 feet. 



7. Drab clay. 



0. Coal, (No. 2,) 8 feet. 

 5. Drab clay. 



4. Sandstone, about 25 feet. 



3. Drab, lire clay, 4 feet. 



2. Coal, (No. 1,) 11 to 14 feet. 



1. Sandstone. 



In bed No. 23 there are three layers of sandstone, which contain a 

 great variety of impressions of leaves. Below coal bed No. 6 there is a 

 bed of drab clay, seven feet thick, with a coal seam at the outcrop, three 

 feet thick ; but the coal appears to give out or pass into clay as the bank 

 is entered, so that there are ten feet of clay above coal bed No. 6. 



Much of the iron ore is full of impressions of leaves in fragments, stems,, 

 grass, &c. The ore is mostly concretionary, but sometimes it is so 

 continuous as to give the idea of a permanent bed. There are several 

 varieties of the ore of greater or less purity. Above coal bed (5) there 

 is a seam of iron, with oyster shells, apparently Ostrea subtrigonalisy 

 or the same species found so abundantly near Brown and O'Bryan's 

 coal mine, about twenty miles southeast of Cheyenne. Nearly a dozen 

 openings have been made here for the coal. 



These coal beds are very valuable, andean be more easily wrought 

 than any in Colorado. The great thickness of the coal strata has been so< 

 uplifted, and the surface worn away, that the beds are all easily accessible,. 

 and one can walk across the uj)turned edges of from 1,200 to 1,500 feet in 

 thickness and then they incline eastward, and die out in the plain. I find it 

 somewhat difficult to give a satisfactorj^ reason why they have not been 

 swept away or concealed by debris, as they have been in most other locali- 

 ties. Leaning against the sides of the mountains between South Boulder 

 caiion and that of the main Boulder Creek, are immense walls of sandstone,, 

 possibly paleozoic or the lower beds of the trias, partially metamorphosed 

 by heat. These walls rise to the height of 1,500 to 4,000 feet above the 

 valley, and thus seem to have protected these formations from the erosive 

 action, which, according to the position that I have taken in this report,, 

 is local, and must have come directly from the mountains. 



A beautiful valley has been scooped out by the South Boulder, leav- 

 ing a bench covered with debris between the two Boulder Creeks. 

 Refore reaching these huge sandstone walls, we pass over a portion of 

 the cretaceous, and a great thickness of the red beds, inclining at a high 

 angle. • 



Immediately south of the South Boulder Creek there is a high bencli 

 that extends up close to the base of the mountains, and is covered with 

 drift and boulders, three miles in width, entirely concealing all the un- 

 changed rocks. But in the valley of Coal Creek, seven beds of coal are 

 revealed by the scooping out of this valley. These beds all incline at a. 



