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 corresponds 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. 3, 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 E 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. 



