1887.] ol [Stevenson. 



the coals diminish. In Lee, Wise, Russell and Tazewell counties, of Vir- 

 ginia, this lower division is either insignificant or wanting — but further 

 north-west, in Greenbrier county, of West Virginia, Prof. Fontaine* found 

 the sandstone division with strings and beds of coal, which, however, are 

 interesting more because of their existence than because of any economi- 

 cal importance. The total thickness of the whole series there is about 

 290 feet. 



No Vespertine is found in or immediately adjoining the Great valley, 

 beyond Augusta county, of Virginia ; but the petty areas preserved on the 

 crests of synclinal ridges are among what Prof. W. B. Rogers termed the 

 Allegheny mountains, in Hardy, Hampshire and Morgan counties, ot 

 West Virginia. There the coals are usually very thin, as they are also 

 under the great anticlinals of Randolph and Tucker counties, of West Vir- 

 ginia, Allegheny county, of Maryland, Bedford, Huntingdon, and the 

 counties further north in Pennsylvania. The coal is present in all of these, 

 but not in such shape as to deserve more than passing notice ; the thick- 

 ness seldom exceeds a few inches and the large percentage of ash leads 

 most persons to regard the coal as anthracite. Along the lines mentioned, 

 the sandstones show a decided thickening, becoming 1100 feet or more in 

 Bedford county, of Pennsylvania ; but the thinning is very marked in a 

 north-westward direction, as the whole thickness in Fayette county, of 

 Pennsj^lvania, is barely 400 feet. There, the last westward exposure on 

 the easterly side of the Appalachian region, it appears to contain no coal. 



The Devonian. 



The Devonian is represented by Chemung and Hamilton only, the Cats- 

 kill and Carboniferous being absent. In Bland and Giles counties Devonian 

 rocks occur in the "Wilderness" area of Kimberling creek, and they 

 make up the great part of Brushy mountain, in the former county ; they 

 underlie the "Poor valley " of Walker mountain, and make the mass of 

 Little Walker and Max Meadows mountains, while a narrow strip lies 

 along the north side of the Draper Mountain fault in Pulaski county. 

 Except in the " Wilderness," where the Oriskany was recognized, no line 

 could be drawn between Devonian and Upper Silurian, the shales of the 

 one passing interceptibly into tlie shale of the other. 



Ghemung. — The Chemung, as seen on the North Holston near Mendota, 

 is 350 feet thick, but it is wholly absent from Stony mountain in Lee county. 

 Eastward, or rather north-eastward in Brushy mountain, the thickness in- 

 creases rapidly, so that north from Saltville, in Smyth county, it is cer 

 tainly twice as great as at Mendota. On the same mountain, in Bland 

 county, the increased thickness is noticeable even to the most careless ob- 

 server, and on the road leading from Walker creek to Hunting Camp 

 creek, the following succession was seen : 



1. Sandstones with some shales. 



2. Conglomerate sandstone. 

 * Loc. eit. , pp. 44 and 45. 



PKOC. AMER. PHILOS. SOC. XXIV. 125. K. PRINTED APRIL 30, 1887. 



