130 : GEOLOGY OF OHIO. 
nearly 1,000 feet in thickness, which are found in the central portion of 
the basin—we have no representatives in Ohio; but of all the others 
the equivalents are found in the different parts of our coal field. These 
will be briefly described in the order of their superposition, beginning 
with the lowest. 
THE LOWER COAL MEASURES. 
In Ohio we have immediately above the Conglomerate, if it be 
present, if absent, resting on the Waverly, a series of six to eight 
workable coal seams interstratified with sandstones, shales, limestones, 
fire-clay, and iron ore, the whole forming a mass having an average 
thickness of about 400 feet, which correspond in a general way with 
the Lower Coal Measures of the Pennsylvania geologists. The coal 
seams of this group have been numbered from 1 to 7, beginning with 
the lowest. These are in part identical with the coal seams which 
have been enumerated by Profs. Rogers and Lesley in western Penn- 
sylvania, our Coal No. 1 being the Sharon Coal of Rogers, Coal A of 
Lesley *; No. 2, the Brookville (?) Coal of Rogers; No. 8, the Clarion Coal 
of Rogers, Coal B of Lesley; No. 4, the Kitanning Coal of Rogers, 
Coal C of Lesley; No. 5, the Lower Freeport of Rogers, Coal D of Lesley ; 
No. 6, the Upper Freeport of Rogers, Coal Ei of Lesley; No.7, perhaps 
the Elk Lick Coal of Rogers, Coal F of Lesley. We also have, in the 
Lower Coal Measures two beds of limestone—underlying Coals Nos. 3 
and 4—which are remarkably constant elements in the group. These 
deserve special mention, as they may be traced almost uninterruptedly 
from the Pennsylvania line to the Ohio, and are the most reliable and 
useful guides in the exploration of the geology of the country traversed 
by them. Higher up in the group are two other limestones, which, 
though less constant, are wide-spread and conspicuous members of the 
series. Of these, one underlies Coal No. 6 in the eastern part of the 
State, and is the Upper Freeport limestone of the Pennsylvania geolo- 
gists; the other overlies Coal No. 7 in Stark, Tuscarawas, and Coshocton 
counties, and is the associate—frequently the representative—of the 
important Blackband stratum of this horizon. Although the Lower 
Coal Measures exhibit many changes in the thickness and character of 
the beds which compose them in passing from county to county along 
their lines of outcrop, still their general structure remains the same, 
and certain elements which they contain are so nearly constant as to 
serve as a skeleton or framework by which the various sections may 
* This is above, not under the Conglomerate, as represented by the Pennsylvania 
geologists. 
