98 STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 



sandstone. The Mesaverde, 5,000 feet at the east, where erosion 

 was less energetic, has three coal groups. The lowest is in the 

 basal part of the formation and underlies a conspicuous white sand- 

 stone, which contains marine fossils. Gale's description suggests 

 that this sandstone may be equivalent to the Rollins of Lee and that 

 the lowest coal group may be in the Lower Pierre, included farther 

 south in the Mancos shale. The coal seams are usually thin and 

 where thick are worthless. The middle coal group, above the white 

 sandstone, is unimportant west from the Utah line, but the seams 

 become thicker toward the east, though they are irregular and at 

 times are broken badly by partings of shale or bone. They become 

 important in the eastern part of the basin ; at Newcastle, there are 

 105 to 108 feet of coal in 7 seams, the thicknesses being 5, 8, 20, 5, 

 45-48, 18 and 4 feet respectively. One seam at Newcastle has a 

 parting of soft coal at 4 to 6 feet from the floor and is troubled by 

 " sandstone dikes." A seam at 40 miles south from Glenwood 

 Springs has 7 to 10 feet of coking coal as the upper bench, but the 

 lower bench is non-coking. The upper coal group is near the top of 

 the Mesaverde ; its coals are unimportant. 



The Green River Basin, north from the Uinta Mountains, is 

 mostly in Wyoming but the southeastern prong extends into Colorado 

 and an outlier remains in Utah at the west. 



The relations of the upper part of the long section in the Coal- 

 ville coal field in Utah appear somewhat uncertain. The area was 

 studied by Tafif and later by Wegemann, the paleontological deter- 

 minations being made by Stanton.'* The boundaries of the several 

 formations are still indefinite, but it is sufficiently clear that the 

 region was near the source of sediment, for sandstone and sandy 

 shale predominate in the upper 7,000 feet of the section. The upper 

 2,500 feet, prevailingly sandy, has yielded leaves and fresh-water 

 shells. The succeeding 1,650 feet contains marine shells and rests 

 on a white sandstone, 200 feet ; below that is a coal seam. This, at 

 4,450 feet below the top of the Cretaceous, is irregular in occur- 

 rence as well as in its relations to the thick sandstones above and 

 below it. It is double or triple at many localities, while at others 



74 T. W. Stanton, Bull. 106, 1893; J. A. Taff, Bull. 285, 1906, pp. 285-288; 

 C H. Wegemann, Bull. 58i-£, 1915, pp. 163, 182. 



