EASTERN OUTCROPS IN THE VIRGINIAS 29 



which underlies the middle or coal-bearing division. The section shows 

 only shales and sandstones for about 1,700 feet, as determined from the 

 dip, of which the bottom 709 feet are assigned to the Pocono.* .Coal 

 beds have been opened at many places along little AValker, in Mont- 

 gomery, Pulaski, and Wythe counties. Thirteen beds are reported 

 within a vertical distance of 400 feet in western Wythe, but only the 

 lowest three become important economically. The thickness varies, as 

 the beds have suffered much from compression, and in man}' cases the 

 shales have been thrust into the coal. The dying of this fault throws 

 out the Mississippian at a little way over in Smyth county .f 



The great Saltville fault has preserved the Mississippian in southern 

 Bland (north from Wythe), as well as in Smyth and Washington, and 

 be3^ond for several miles in Tennessee. The exposures in Bland were 

 not such as to admit of measurement. The coals continue into Smyth 

 and the hard sandstone, the " Quarry " of Wythe county, the 80-foot 

 rock of Lewis tunnel, underlies them. The thickness in Smyth was es- 

 timated at 500 feet, but in this were included rocks which afterward were 

 referred to an earlier period. A noteworthy change begins in eastern 

 Smyth, for there impure limestones appear in the shales and the passage 

 to the overlying limestones is very gradual.^ This change is very rapid 

 toward the southwest, for when one has reached the middle of Washing- 

 ton county, adjoining Smyth, he finds the Pocono so linked with the 

 great limestone mass that the separation can be made onl}^ with great 

 difficulty. 



It is possible that the lowest coal bed may be persistent thus far, for 

 coal is said to have been digged at low water in the Holston river, 

 near Mendota. The Pocono here is the Protean or lower division of 

 Safford's Silicious group and the lower division, the great sandstone, 

 is evidently a part of the Grainger shales of Mr M. R. Campbell, which 

 carry Devonian fossils. In Wise county, about 40 miles west, the 

 Pocono is about 150 feet thick on the waters of Powell river, where it 

 consists of more or less calcareous sandstones with some shale. § At 

 probably 15 or 20 miles northwest in Whitely county, of Kentucky, 

 where the Pine Mountain fault brings these rocks up, the thickness is 

 estimated at fully 150 feet by Professor Crandall.|| 



* J. J. Stevenson : A geological reconnaissance of Bland, Giles, Wythe, and parts of Pulaski and 

 Montgomery counties of Virginia. Proc. Amer. Phil. Soc, vol. xxiv, 1887, pp. 105, lOG. 

 t J. J. Stevenson : Op. cit., pp. 78, 79. 



I J, J. Stevenson : Notes on the geological structure of Tazewell, Russell, Wise, Smyth, and 

 Washington counties of Virginia. Proc. Amer. Phil. Soc, vol. xxii, 1884, pp 135, 143. 



§ J. J. Stevenson : A geological reconnaissance of parts of Lee, Wise, Scott, and Washington 

 counties, Virginia. Proc. Amer. Phil. Soc, vol. xlx, 1881, pp. 242, 259. 



II A. R. Crandall : Geological Survey of Kentucky, Geology of Whitely county and part of Pulaski 

 county. 



