Stevenson.] ^^ [August 20, 



Here, beginning at Stone mountain, one finds as before the Coal Meas- 

 ures, Conglomerate and Lower Carboniferous forming tliat mountain ; in 

 the valley, the black shales are shown at the base of each ridge, while the 

 Lower Helderberg rocks occupy the center of the valley, where they de- 

 scribe an anticlinal, exceedingly sharp near the axis, but showing much 

 gentler dips on each side as Stone and Powell mountains are approached. 



Fid. 2. 



Fig. 2.— Cross-section from crest of Stone Mountain to that of Powell Moun-^ 

 tain. The dotted lines show extent of material removed by erosion. 



It is altogether probable from the best information attainable that a fault, 

 rudely parallel to Stone mountain, exists in Kentucky at but a little way 

 from the State line. 



The general structure of the region between Black mountain and the 

 Clinch river will be discussed in another part of this paper. 



The Coal area between Black mountain and Stone mountain is extensive, 

 but that within Hunter's valley is insignificant. 



The Coal Area Drained by Pigeon and Roaring Forks op 

 Powell River. 



The Coal area, which begins immediately behind Stone mountain and 

 extends thence to beyond the crest of Black mountain, is evidently the 

 same with Ihe Kentucky series, so well exposed in Harlan and Letcher 

 counties of that State. "■ The upper part of the Serai (Pottsville) Conglomer- 

 ate forms the northern face of Stone mountain and the Coal Measures come 

 in at the foot of the ridge, where the dip is very nearly vertical. 



A series of barometrical observations shows that the series rises eastward 

 from the mouth of Callahan creek, about a mile above the head of Big 

 Stone gap. This rise of the whole region is rapid and is sufficient, if con- 

 tinuous, to carry most of the beds into the air within a few miles ; so that 

 only the lowest beds could be found at but a little way beyond the Little 

 Stone gap. 



For the most part, this region is still a wilderness, and exposures rarely 

 occur except in the stream beds, which, owing to rapid fall, are Usually 

 clear. Several of the tributaries to Roaring fork were followed almost to 

 their heads in the south-east side of Black mountain ; and this general sec- 

 tion was compiled from the measurements made on them. 



