Stevenson.] -<ad(J [Jan. 21, 



part of that ridge to beyond the Tennessee line. Its beds are thrown over 

 at a higli angle, varying from 80 to 90 degrees, and its area is not materially 

 wider than the thickness of the group. The same group occurs also on the 

 easterly portion of Powell mountain. 



This group is not far from 1000 feet thick, and is made up of sandstones, 

 shales and coal beds. The highest stratum is a sandstone, known as the 

 "Bee rock," which is about 135 feet thick, and is a marked feature 

 along the northerly side of Stone mountain from Little Stone to Penning- 

 ton's gap. This bed is more or less conglomerate. The lowest bed, also, 

 is conglomerate, and is about 45 feet thick. Sandstones and conglomerates 

 prevail, and some of the latter are very coarse. Six coal beds were seen in 

 Pennington's gap and a seventh was found on Powell mountain. 



The coal beds are variable in thickness, and in the quality of their coal, 

 so that none of them attains to real economic importance. Those in Stone 

 mountain have suffered severe crushing, and are apt to be pockety. The 

 best is that which immediately underlies the "Bee rock," and varies from 

 one to three feet. The same bed is even more irregular on the southerly 

 face of Powell mountain, where its thickness is from 2 to 14 inches. A 

 second bed of workable thickness was seen in Powell mountain, but it is 

 concealed in both Big Stone and Pennington's gaps. This, at not far 

 from 350 feet below the top of the group, is from 2 to 3 feet thick, and 

 seems to hold a place very nearly like that which is mined for coking at 

 Quinnimont. In Powell mountain, however, the coal is sulphurous, and 

 can be used only for domestic purposes. 



The coal beds in the greater part of the Tennessee coal-field belong to 

 this group, and, without doubt, much of the section obtained in the north- 

 eastern district of that coal-field should be referred to the same horizon, as 

 Prof. Safford has done. The coal beds there are somewhat variable. A 

 noteworthy feature of this group in Tennessee is that the bottom plate of 

 conglomerate is absent, and the Coal group passes directly into the Lower 

 Carboniferous. 



The Lower Carboniferous. 



The two divisions of Lower Carboniferous recognized in Tennessee by 

 Prof. Safltord, and named by him the Mountain Limestone and Silicious 

 groups, are fully represented here. These names are used in this memoir 

 in preference to those now used in Pennsylvania, because in this region, 

 the old division of Lower Carboniferous into Umbral and Vespertine or 

 Nos. XI and X would place all the limestone together, and thereby do 

 violence to the actual relations of the beds. 



The beds of this series are well shown along Stone mountain ; on the 

 bluff of Powell mountain overlooking the valleys of North Fork of Clinch, 

 and the South Fork of Powell river, and in Brushy mountain near the 

 North Fork of Holston river. 



The Mountain Limestone Group. 

 This group exhibits some sui'prising variations. Along Stone mountain, 

 the section as shown in Pennington's gap is 



