134 STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 



bituminous, but it is of better quality in respect of ash than the 

 Montana coals at the same horizon. 



The Benton Coals. — The published reports contain no reference 

 to occurrence of coal in deposits representing the Niobrara time 

 interval ; the coal seams are associated with rocks containing Benton 

 fossils. These coals are confined to the western part of the Cre- 

 taceous area within Arizona and Utah, though extending eastwardly 

 for a short distance into New Mexico, Colorado and Wyoming. The 

 coal in Arizona and New Mexico is rather high in ash, about 14 to 

 16 per cent., and the sulphur seems to be not far from 2 per cent., 

 so that it is an inferior fuel. Analyses I., II. and III. are from 

 Iron County, Utah, where the coal seams are often closely associated 

 with marine limestones ; IV. is from Emery County, where the coal 

 is mined extensively ; V. and VI. are from Uinta County, on the 

 northwest side of the Uinta Basin. 



The carbon is highest at the west in Iron County, being more than 

 83 per cent, in the pure coal of I. ; it is 78 in the pure coal of III., 

 81 in that of II. and 81 in the best coal from the Emery coal field. 

 The sulphur in Iron County is so abundant as to suggest contribu- 

 tion by animals. V. and VI. are the upper and lower benches of a 

 single bed and show improved conditions during formation of the 

 upper bench. Lee has given analyses of the upper and lower benches 

 of a bed in Delta County of Colorado ; the upper bench has 6 per 

 cent, and the lower bench 22 per cent, of ash. There, as in the 

 Uinta County seam, the lower bench, though richer in ash, is poorer 

 in volatile. The Frontier coals in Uinta County of Wyoming, in 

 the Green River Basin, have excellent fuel in several of the seams. 

 They are bituminous, low in ash and sulphur and have from yy to 

 almost 81 per cent, of carbon. ^*^ 



141 Bureau of Mines, Bull. 22, pp. 47, 139; for Utah, pp. 80, 193, 194; C. 

 T. Lupton, Bull. 628, p. 80; W. T. Lee, Bull. 510, p. 201. 



