STEVEXSOX— INTERRELATIONS OF FOSSIL FUELS. 77 



Fox Hills. The coal seams are irregular except in the northern part 

 of the district, where beds were seen, 8, 6 and 4 feet thick. Whether 

 these belong to Fox Hills or to Laramie cannot be determined from 

 the sections. In the southern portion of the basin, within Colorado, 

 the Laramie is 900 feet thick according to Fenneman^' and Gale, 

 consisting of alternating sandstones and shales, with indications of 

 20 lignite seams distributed irregularly in the upper two thirds. 

 The writer regards the lower third as belonging to Fox Hills and 

 thinks that the thick coal seam near Craig, 8 feet, is in that formation. 

 Northward from the Green River Basin, areas of Laramie are 

 comparatively unimportant. On the west side of the Bighorn 

 basin, lenticular coal beds were seen by Woodruff at many places 

 in the lower part of the formation. W^ashburne found 150 to 

 700 feet between the Eocene and the Pierre formation, massive 

 sandstones and shales ; in this, taken to be Laramie, there are thin 

 and variable coal beds. The only workable seam is near Garland 

 where 4 feet of clean coal had been worked ; but the seam quickly 

 breaks up in all directions and becomes worthless. The Buft'alo 

 coal field, east from Bighorn ^Mountains, shows great irregularity 

 in deposition during the Laramie, but the coal seams, though vary- 

 ing in thickness and quality, can be traced for considerable distances. 

 In the Sussex coal field, 30 miles farther south, Wegemann found 

 the Lance formation, 3,200 feet thick and resting on the Fox Hills. 

 The coals are unimportant except in two localities, where seams oc- 

 casionally become workable. W^egemann's descriptions seem to 

 make clear that the coals are mere lenses and the better coal is in the 

 middle portion of the lens. Winchester measured abour 2,450 feet 

 of Lance beds in the Lost Spring coal field, which is on the western 

 border of the great Tertiary lignite area. There are traces of the 

 coals seen farther west, but only carbonaceous shale was found. 

 The Fox Hills, Lance and Fort fnion appear to be conformable 

 in this region. The highest rocks in the Black Hills area of north- 

 eastern Wyoming are sandstones, shales and lignites, in all about 

 2,500 feet, as determined by Darton. That student hesitated to 

 identify these beds as Laramie, because it was not possible to deter- 

 mine whether or not they are conformable to the underlying Fox 



3' N. M. Fenneman and H. S. Gale, Bull. 285, 1906, p. 288. 



