STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 105 



southern portion of the Bighorn Basin. Coal is present in the Clag- 

 gett and the Eagle. The Claggett seams are very thin, nowhere ex- 

 ceeding 21 inches, and in all cases the coal is so dirty as to be worth- 

 less. The Eagle seams are of capricious distribution. There are 

 workable beds in the southeastern corner of the basin, but they dis- 

 appear northwardly before Bighorn County is reached and are re- 

 placed with yellow sandy shales. Black shales appear north from 

 the city of Basin and these near Garland contain very thin seams of 

 coal. Elsewhere in that neighborhood, these coal horizons are 

 marked only by black shale with coaly streaks. An anticline near 

 Silvertop, close to the Wyoming- ^Montana line, brings up the Eagle. 

 There is but one workable seam in that formation on the Wyoming 

 side, but there are two beyond the line in Montana. The Bridger 

 coal field is west from the anticline and extends along the Chicago, 

 Burlington and Quincy railroad to beyond Bridger in Montana. 

 Some important coal deposits are in the Montana portion, but none 

 in Wyoming, and all trace of coal disappears at a short distance 

 west from the railroad. The Eagle coals are all well-jointed and 

 show no woody structure. They illustrate well the irregularity of 

 coal deposits in an extended area. 



The eastern part of ^Montana is a rolling plain, the mountains of 

 Wyoming, Colorado and New Mexico having become insignificant, 

 as the disturbed area is confined to the western border ; but moun- 

 tain-making was energetic there, west from the 109th meridian, and 

 the whole section of Cretaceous is shown at many localities. In this 

 disturbed area, one is west from the Bighorn Basin, as well as the 

 western boundary of Colorado and New Mexico, so that conditions 

 should bear resemblance to those observed in Arizona, Utah and 

 western Wyoming. 



The most southerly coal field is that near Electric, in Park 

 County, about 100 miles west from Bridger. There as well as in 

 some petty areas at the north, Calvert*^ was unable to recognize the 

 subdivisions of the Pierre and grouped the section, about 1,000 feet, 

 as Montana. The upper portion, about 330 feet, consists of sand- 

 stone and shales with some carbonaceous shale but no coal; the 

 middle portion, about 230 feet, is largely sandstone and sandy shale 



85 W. R. Calvert, Bull. 471-E, 1912, pp. 28-66. 



