114 STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 



bituminous coal which contains much resin. Eastwardly along this 

 southern border no workable seams occur, while farther north along 

 the eastern outcrop only traces of coal were seen. The sandstone 

 decreases in that direction. Lee appears to have found no coal in 

 the Colorado beds along the northeastern border of the basin, but he 

 was able to recognize the Tres Hermanos sandstone. 



In Arizona the near approach to the source of sediments is mani- 

 fest. The most southerly fragment of Cretaceous is the Deer Creek 

 coal field, ^°* about 150 miles southwest from the southern termina- 

 tion of the San Juan Basin, near the jvuiction of the Gila and San 

 Pedro Rivers. In the lower or southern part of the field, according 

 to Campbell, 400 to 500 feet of coarse greenish gray sandstone with 

 some shale rest on the Carboniferous limestone. The fossils are 

 imperfect and suffice only to prove Cretaceous age. Three coal 

 seams, much broken and thin, were found in a shaft within the 

 basal 60 feet. The coal is poor ; the best has 34.78 per cent, of ash. 

 The Pinedale coal field is about 100 miles north from the Deer 

 Creek area. There Veatch"^ found about 500 feet of deposits con- 

 taining Benton fossils as determined by T. W. Stanton. The two 

 coal seams are near the base, 10 to 15 feet apart, and are only 25 

 feet above rocks of Pennsylvanian or Permian age. The seams are 

 12 and 3 feet thick, but coal from the upper one is very bad, having 

 54 per cent, of ash. The lower one has some good coal with only 

 10 per cent. A much more extensive field is that of the Black 

 Mesa^'^'' in the northeastern corner of the state. The Cretaceous is 

 about 700 feet thick and coal seams were found near the base as 

 well as above the middle. The lower group is within the basal 55 

 feet and its seams are 7 and 15 feet thick. The upper bed yields a 

 fairly good coal, bituminous and with about 14 per cent, of ash. 

 The lower seam is a worthless mass of shale and coal. The higher 

 beds show numerous seams 2 to 12 feet thick ; the coal is evidently 

 inferior, but in default of better material it is used as fuel. 



Benton deposits are present in isolated areas within Utah as far 

 west as the 113th meridian along the Arizona border. Almost 45 



104 M. R. Campbell, Bull. 225, 1904, pp. 241-258. 



10s A. C. Veatcli, Bull. 431, 1911, pp. 239-241. 



io« M. R. Campbell and H. E. Gregory, Bull. 431, pp. 229-238. 



