118 STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 



that work was abandoned in one mine because the bed thinned ab- 

 ruptly, the coal being cut out by a " sand roll " or deposit of coarse 

 sand and gravel in the roof of the bed. At about 850 feet below 

 the Wasatch seam, thin coals were seen, which are known as the 

 Spring Canyon beds. The coal is impure and worthless ; it is pos- 

 sible that these belong at a Bear River horizon. 



The Coalville field is an outlier of the Green River Basin, which 

 is reached in Uinta County of Wyoming near the iiith meridian 

 or nearly 100 miles west from the Utah-Colorado line and probably 

 25 miles east from the meridian passing through Emory in Castle 

 Valley field of Utah. The relations of the lower part of the sec- 

 tion were a source of much perplexity, as the fresh- water fauna had 

 led to the belief that it belonged to the Laramie or possibly even to 

 the Tertiary. Its place in the column was determined by Stanton^^^ 

 who showed that it intervened between coarse sandstones and con- 

 glomerates below and well-defined Colorado above. Knight^^* rec- 

 ognized an important coal-bearing formation in the southern part 

 of the county, which he named the Frontier. It consists of thick 

 sandstones with coal beds and it may be practically equivalent to 

 the deposits containing the Wasatch seam at Coalville. At a later 

 date Veatch reported upon the southern and Schultz^^^ upon the 

 northern part of the county. The thickness of deposits in this 

 area is enormous ; Veatch assigns not less than 2,000 feet to the 

 Niobrara, 4,200 to the Benton and o to 2,400 to the Bear River. 

 The Frontier sandstone formation, the upper part of the Benton, 

 is about 2,400 feet thick, consists of alternating sandstones and 

 clays, with numerous coal seams. The important coals are the Kem- 

 merer group near the top, consisting of 3 seams within a vertical 

 distance of 90 feet ; the highest bed has an extreme thickness of 5 

 feet, the main Kemmerer is from 5 to 20 feet thick in the mines, 

 but along the outcrop, the variability is much greater, for at some 

 localities between the mines it is very thin, at times absent. At 550 

 feet below the main Kemmerer is the Wilson bed which is not 



US']" \Y Stanton, "The Stratigraphic Position of the Bear River Forma- 

 tion," Amcr. Joxirn. Set., Vol. XLIIL, 1892, pp. 98-115. 



^^* W. C. Knight, " Coalfields of Southern Uinta County, Utah," Bull. 

 Gcol. Soc. Amcr., Vol. 13, 1902, pp. 542-544. 



ii-"' A. C. Veatch, Bull. 285, pp. sz2i, 2>?)7, 340 ; A. R. Schultz, Bull. 316, p. 215. 



