158 STEVENSON— INTERRELATIONS OF THE FOSSIL FUELS. 



degrees. The coal, as far as proximate analysis shows, is a very 

 fair bituminous coal. The deposit is irregular and, in one direction, 

 thins away within two miles. 



Eocene deposits cover a great part of eastern Wyoming. Taff--- 

 found that, in the Sheridan coal field, the upper member of the 

 Fort Union, about 2,200 feet thick, consists of friable, loosely con- 

 solidated sandstones, coal beds and slightly indurated shales, all with 

 gentle dip, seldom exceeding 4 degrees. The coal beds are in three 

 groups ; the lower or Tongue River contains ascending the Carney, 

 Monarch, Dietz, No. 3, No. 2 and No. i, Smith and Roland coal 

 beds, all of which are of workable thickness, the thinnest being 5 and 

 the thickest somewhat more than 30 feet thick. The Intermediate 

 group contains some lens-like coal beds, which at some places are of 

 sufficient thickness for mining. The Ulm group or highest has two 

 beds 16 and 12 feet. Nearly all of the beds are at least double and 

 some of the highest beds are broken by partings. The coal is ap- 

 parently almost uniform throughout; the weather attacks all alike. 

 The only important distinction is that coal from the Intermediate 

 and the Ulm has somewhat more water and shows the texture or 

 fiber of some plants, whereas that from the Tongue River, though 

 high in water, shows no woody texture to the naked eye. The 

 thicker beds for the most part are without lamination ; silicified 

 wood is not rare. 



Wegemann--^ examined an area contiguous to that studied by 

 Tafif in northeastern Wyoming and continuous with the extensive 

 fields of eastern Montana and western Dakota. The exposed rocks, 

 about 1,000 feet thick, belong to the upper part of the Intermediate 

 and lower part of the Ulm, as defined by TafT. Wegemann saw 

 many local unconformities and great variations in the rocks. A 

 notable feature is the coarse sandstone filling channels in beds of 

 coal and shale, due clearly to subaerial erosion. The cross-bedded 

 sandstone denoting shallow water, the fine shale, proof of quiet 

 water, the numerous coal beds and the repeated evidence of sub- 



-22 J. A. Taff, " The Sheridan Coal Field, Wyoming." U. S. Geol. Survey, 

 Bull. 341, 1909, pp. 127-130, 133, 144-147- 



-23 C. H. Wegemann, " Barber Coal Field, Wyoming," U. S. Geol. Survey, 

 Bull. 531, I., 1913, pp. II, 12, 19. 



