176 GEOLOGICAL SURVEY OF THE TERRITORIES. 



show that the coal compares favorably with the lignites fonnd iu other 

 parts of the West. 



Anthracite Creelc. — In the report for 1873 I spoke (page 259) of the oc- 

 currence of anthracite coal in the Elk Mountains. It is found at the 

 heads of Eock Creek, Slate Eiver, Anthracite Creek, and Ohio Creek. 



It is probably all of Cretaceous age, and was doubtless originally a 

 bituminous lignite. The coal at the head of a small branch of Anthra- 

 cite Creek was found in a bed from 4 to 5 feet thickness in sandstones. 

 The section has been given in a preceding chapter. These sandstones 

 were tipped up against a range of trachytic peaks, and between the 

 layers of sandstone, some distance above the coal, is a layer of trachyte. 

 The strata dip at an angle of 20° to 25°. This coal is probably a 

 portion of the same bed from which the coal on Coal Creek was ob- 

 tained, although in the latter case it is lignitic. The eruption of the 

 trachyte found near the coal first mentioned probably so heated it as 

 to deprive it of the bituminous matter. This coal from the head of 

 Anthracite Creek has a submetallic luster, is black even in powder, and 

 has a conchoidal fracture. 



Analysis No. 1. 



Water 2.00) . „ 



Volatile matters - 2.50$ *'* 



Carbon 91.90 



Ash (of a dark reddish-brown) 3. 60 



100. 00 



Analysis No. 2. 



Water 1.60? 5 0Q 



Volatile matters 3. 40 £ 



Carbon 88.20 



Ash (same as No. 1) 6.80 



100. 00 



These analyses prove the coal to be of excellent quality. Neither of 

 the specimens coked. The percentage of water and volatile matters 

 and the amount of ash compare favorably with other anthracites. 



Oh be Joyful Creelc. — The coal on this creek is also an anthracite. It 

 was discovered in 1S74, and the following notes were obtained from Mr. 

 Holmes, who visited the bed. It is two feet in thickness, between beds 

 of quartzitic sandstones and metamorphosed shales, which dip slightly 

 to the west. The coal outcrops about 1,500 feet above the level of Slate 

 Eiver at the mouth of the creek, two miles up the stream. This coal 

 probably belongs to the same horizon as the coal on Anthracite Creek 

 and on Eock Creek.. It probably outcrops again at the head of Slate 

 Eiver. A specimen collected by M.r. Holmes has a submetallic luster, 

 is black, with rusty-colored surfaces from the presence of iron, a fracture 

 somewhat cuboidal, breaking also into layers. This coal seems to be of 

 poorer quality than that of Anthracite Creek and Eock Creek. 



Analysis. 



Water 4.00? lg 0Q 



Volatile matters 14.00 5 



Carbon 74.00 



Ash (of a reddish color) 8. 00 



100. 00 



It would perhaps be more properly described as a semi-anthracite. 

 The sandstones and shales surrounding it are penetrated by numerous 

 dikes and mineral lodes. 



