4 2 4 THE POPULAR SCIENCE MONTHLY 



steep to the northwest. The main topographic features of the region 

 have a general northeast-southwest trend, and are related in a broad 

 way to the structure. But detailed study of small areas within the 

 field emphasizes very clearly that the structure is much more complex 

 than is indicated by a general study of the field. This complexity is 

 due to folding, to faulting, and in the northeastern part of the field, 

 to associated igneous rocks. Apart from a few well-defined lines of 

 faulting with northeasterly and southwesterly trend, there are many 

 small faults running in various directions. Moreover, within small 

 areas in the field the strikes and dips are often irregular. The rocks 



View taken fkom Doughton Peak, looking to the left of the ridge running northward 

 and named Carbon Mountain. Shows structure of the coal-bearing rocks. 



are frequently xcvy much broken and jointed, and slickensided sur- 

 faces, especially in the coal, are common. 



This complex structure was produced by the intense crustal move- 

 ments to which the rocks were subjected during late Tertiary or post- 

 Tertiary time. Eecent subsidence of the region is indicated by tbe 

 presence of alluvial deposits, in places several hundreds of feet in 

 thickness, in the broad valleys now occupied by comparatively small 

 streams. 



The Coal 



The coal beds are restricted to the Kushtaka formation which has a 

 known surface area of about 50 square miles. The evidence is fairly 

 clear that an additional area of more than 20 square miles underlies 

 the Tokun formation at varying depths. The coal beds are distributed 

 throughout the thickness of the Kushtaka formation. "Where sections 



