Williams, i STEVENSON. 89 



seam." The limestone overlying this coal in northern Ohio and Pennsylvania, as 

 well as in the northern part of West Virginia, is greatly diminished in thickness, and 

 is represented in this locality by calcareous shale only, containing a few nodules of 

 limestone. 



The Barren group has about 300 feet of thickness, and contains no workable coals; 

 it varies but little in thickness from Pittsburgh to the Great Kanawha, running north 

 and south. 



The development of the Lower Coal group in this valley is extraordinary. In north- 

 ern West Virginia the thickness is scarcely 200 feet ; in the first geological district 

 of Ohio it is rarely more than 300 feet ; in either case containing only six or seven coal 

 beds. In this valley it can be separated into two portions, the upper of which is no 

 less than 900 feet thick, with fifteen beds of coal, and the other about the same thick- 

 ness with two or three more coal beds. This development continues southwesterly 

 nntil its thickness becomes about 2,500 feet in Tennessoe. 



The Mahoning sandstone, at the top of the group, is conspicuous in the river hills 

 above Charleston, and holds a coal about midway, as in its northern extension in 

 Ohio and Pennsylvania. It rests upon a variable bed of black flint, 5 to 12 feet 

 thick. A few feet below the flint, and separated from it by shale sometimes arena- 

 ceous, is a coal partly cannel and partly bituminous, from 5 to 7 feet thick. It is 

 regarded as identical with the Upper Freeport of Pennsylvania, and is known locally 

 as the Stockton seam. Below this is a variable bed, at Cannelton a cannel of insig- 

 nificant thickness, at Coalburg, it is the " Great Splint Coal," in some respects the 

 most important bed along the river, and at the Kanawha Salines the place is occupied 

 by several thin beds considerably separated. The bed is from 6 to 11 feet in thick- 

 ness. In the thin layer of clay between the sandstones and coal are numerous im- 

 pressions of Lepidodendron and Sigillaria, and there were remarkably fine leaf-scars of 

 Bothrodendron discovered in one locality. The dark slate found iu this bed is rich in 

 bitumen. Five hundred and fifty feet below the Stockton seam, at Cannelton, is a 

 bed of bituminous coal nearly 7 feet thick, known as the " Gas Coal," and below this 

 coal a limestone was observed by Mr. Ridgway which he identified as the "Ferrifer- 

 ous" of Pennsylvania; if he is correct, the "Gas Coal" is probably the "Kittan- 

 ning " of Pennsylvania. 



J. J. Stevenson, 1 in 1874, presented a paper to the New York Ly- 

 ceum of Natural History which embodies the results of an examina- 

 tion and comparison of the Ohio coals with those of Pennsylvania and 

 West Virginia. The observations recorded cover only that portion of 

 the field north of the Baltimore and Ohio Railroad in West Virginia 

 and Ohio. 



The limits of the Upper coals are first considered, and the conclusion 

 reached that the Pittsburg coal, the base of the Upper Coal Measures, 

 " once reached as far west as Sonora, 71 miles west from Wheeling, 

 and to a point northward not' less than 50 miles from that city, a tor- 

 tuous boundary line connecting the two points." 



Several sections from Ohio, West Virginia, and Pennsylvania are 

 compared in order to ascertain their relations to each other. From 

 this comparison it is found that only Coal VIII, Villa, VHIb, and Coal 

 XI can be seen in all the sections. Coal VIII is the Pittsburg, Villa 

 appears as the Eedstone, VHIb as the Sewickley, while Coal XI is the 

 WayUesburg. 



• The Upper Coal Measures west of the Alleghany Mountains. New York Lyceum Nat. Hist., 

 Annals, vol. 10, 1874, pp. 226-252, pi. No. 12. 



