Stevenson.] ■'■^^ [Nov. 21, 



erly extension of Clinch. No attempt was made to follow it to its head. 

 The erosion above the first forks is very deep and there is some reason to 

 suppose that Hudson beds have been reached ; but as this is merely con- 

 jecture the space is colored on the map as Silurian. 



The Devonian and Lower Carboniferous are exposed in numerous gaps 

 through Brushy mountain where the Vespertine's notable increase in thick- 

 ness is very well shown. The upper bluff of the Chemung is more than 

 200 feet thick and forms a bold cliff. 



The "short" road to Saltville reaches the North fork of Holston at 

 somewhat more than five miles below that village and thence follows all 

 the windings of the stream. It exposes the lower limestones of the Lower 

 Carboniferous and excellent collections of fossils can be made at several 

 places. Twice it passes wholly below the limestones and enters the 

 Vespertine, reaching the black shales which contain streaks of impure 

 coal. As the road approaches Saltville it leaves the river and goes through 

 a little ravine, in which the massire limestones of the Lower Carboniferous 

 are exposed. The synclinal observed on Wolf run is crossed before Saltville 

 has been reached, but the anticlinal is concealed, as much of the Saltville 

 basin has been eroded from it, the axis passing very near the railroad 

 station. Calcareous shales of the Lower Carboniferous make up the hills 

 on the northerly side of the Saltville basin and are very fossil iferous. 

 These hills are rounded and are so nearly of the same height that they may 

 be remnants of a terrace. The hills on the opposite side of the valley are 

 rugged, heavily wooded and show a cliff of Knox limestone. 



The peculiar features of this Saltville basin, with its salt and gypsum 

 will be discussed in another part of this memoir. 



Only Cambro-Silurian rocks are shown between Saltville and Glade 

 Spring and the dip appears to be regularly south of south-east. The Wal- 

 ker mountain fault is crossed at but a little way from the water-station, 

 nearly two miles from Glade Spring. The turnpike from Glade Spring to 

 Bristol is, for a great part of the way, very near the line between Knox 

 and Trenton, and for miles at a time the surface material is very red, the 

 characteristic color of this horizon and of another nearly midway in the 

 Knox group. 



Walker mountain increases in height very rapidly eastward from Glade 

 Spring and it is soon double, one ridge being capped with white Medina 

 and the other with Chemung. The red Medina is fairly well shown, near 

 Lyons gap, where some of the layers contain many Hudson forms. The 

 yellow shales of the Hudson are not well shown but the limestones of the 

 Trenton are well exposed on the Rich Valley road and thence until near 

 Saltville, where the Knox beds are reached. 



In going eastward from Saltville along the Tazewell pike, one finds im- 

 mediately beyond the first fork of the road an exposure of Lower Car- 

 boniferous dipping south-eastwardly, showing that the anticlinal has not 

 been cut away wholly. Beyond the North fork of Holston Lower Car- 

 boniferous limestones are shown dipping south-eastwardly, at from 10 to 



