WORKABLE SEAMS IN THE CINNABAR FIELD. 



355 



of the mine shows this seam to vary considerably in thickness, the bed rolling, 

 and the dip, which is some 20° at the opening, increasing to 60° within 

 300 feet from the mouth of the tunnel. 



The southern entry is the old opening on the lower of the coals. The 

 seam, as exposed here, shows the rapid variation of the benches. Thus one 

 section shows the following thicknesses: top coal 12 inches, parting 36 

 inches, lower coal 36 inches ; while on the southern side of the same work- 

 ings the top coal is 36 inches and the bottom coal 12 inches, with the same 

 thickness of parting. 



The "main" or middle seam (B, figure 1) is overlain by a heavy, massive 

 sandstone, which forms a smooth and hard roof, requiring but little tim- 

 bering. 



Evarts. 



HoTE, 



Craig. 



Figure 2— Sections of workable Coal Seams in the Cinnabar Field. 



Notwithstanding the disturbances to which this part of the field has been 

 subjected, it will no doubt be thoroughly exhausted before abandonment, 

 owing to the excellent quality of coal which the seams yield. 



The most promising part of the Cinnabar field is southwest of the Horr 

 workings. The slope east of Cinnabar creek is dotted with prospect holes, 

 and the coal seams have been traced southward to the park boundary and 

 the base of Electric peak. A part of this area is controlled by the company 

 now developing the Craig mine. 



The sag south of Cinnabar mountain is formed of the argillaceous rocks 

 underlying the coal-measure sandstones, somewhat crushed and broken by 

 the sharp synclinal break. South of this sag the coal-bearing sandstones 

 form outcropping ledges dipping toward the west. Near the little lake 

 back of Cinnabar mountain these sandstones end in a very sharp synclinal 

 upturn, which brings up the underlying argillaceous series, faulted against 

 volcanic rocks. The three entries of the Craig mine are driven in the 

 coal seams at this synclinal, the longest being made for an expected output 

 of 500 tons a day. 



On the eastern side of Yellowstone river the Bowers mine is the only one 

 now worked. The mine is in a triangular block of the coal-measures, lying 

 faulted against the gneiss on the northern side of Trail creek. The coal is 



