160 GEOLOGY OF OHIO. 
county, and the Webster Cannel of Scioto county. Many neighbor- 
hood mines are opened in the seam through these districts. 
Through the southern portion of the State, it is parted from its 
limestone by an interval ranging from 12 to 40 feet ; the limestone itself 
being for the most part replaced by a block iron ore. 
5. THe TIonesta Coat. 
Synonyms.—Coal No. 3b of Report on Hanging Rock District, vol. III; Wartman coal, 
do; Bolivar coal of Stark and Tuscarawas counties. 
This seam is less reliable as a geological element than the Mercer 
coals which have been last described, but still it is found in numerous 
sections throughout, the entire field. It is mined in Mahoning, Stark, 
Tuscarawas, Holmes, and Vinton counties, and to a little greater extent 
in Tuscarawas than elsewhere, though even here its yield is insignificant. 
Its position is 10 to 20 feet above the Upper Mercer limestone or its 
representative in Southern Ohio, the Franklin Furnace Block ore (Main 
Block ore of the Ohio Valley). Its largest measure is 5 feet, but this 
thickness is rarely reached. The seam is of but little value in Ohio. 
6. THE BROOKVILLE COAL. 
Synonyms.—Coal No. 4 of Stark county; Gray Limestone coal; Upper Limestone 
coal; Winters coal of Vinton county; Flint Vein, do; Conway coal 
of Lawrence county; Coal IIIc of Report on Hanging Rock District, 
vol, III. 
This is a much more valuable seam than any that we have found 
since leaving the Sharon coal, or Coal No. 1. A question must be 
admitted as to the equivalence of the Brookville coal of Pennsylvania 
with the Gray Limestone coal, or Coal No. 4 of Newberry, from the 
fact that no limestone is reported in the Pennsylvania sections as 
accompanying the former seam; but the Gray Limestone coal of Stark 
county holds the exact place and relations of the Brookville coal. If 
the two coals are not one and the same seam, then the Brookville coal 
has no representative in Ohio, and the Gray Limestone coal is without 
representation in Pennsylvania, a conclusion that no one acquainted | 
with the demonstrable continuity of the remaining seams of the series 
will be prepared to admit. 
It will be remembered that the Putnam Hill limestone dies out in 
Mahoning county, as it is followed eastward, and in Perry county, as it 
