912 =«C. ; GEOLOGY OF OHIO. 
tainly one of the lowest coal seams of Southern Ohio. It has not been — 
established that the various exposures of low coal found on the western 
side of Jackson and Vinton counties, and on the eastern side of Pike, all 
belong to the same horizon, but it seems probable that they are to be a) 
referred. The westernmost of these exposures are all «ntra-conglomerate 
coals. ‘They rest directly, or with the interposition of a few feet of shale 
and fire-clay, upon conglomerate rock, and they are covered with heavy 
ledges of conglomerate. On sections 21, 22, 27, 28, of Jackson township, 
Jackson county, not less than forty feet of pebble rock are shown above 
the coal. On the east side of section 25, same township, on the land of 
J. Wilson Case, a seam, measuring three feet in thickness, is overlain by 
a ledge of very coarse conglomerate, the pebbles of which are cemented 
with iron ore. The overlying conglomerate is also shown in full force on 
sections 19, 22, and 31 of Jackson township, Pike county, and also in 
Union and Marion townships of the same county. 
The underlying conglomerate in all these cases is the first main seam 
that is reached in the ascending scale of the State. The Pike county 
sections furnish the means of connecting the coal seains directly with 
well-known and definitely-marked horizons of the lower recks. The 
coal is not more than five hundred and seventy feet above the Huron 
Shale, and not more than four hundred and fifty feet above the Waverly 
Black Shale. 
2. About one hundred feet above the Shaft Coal a second seam occurs, 
which, like the one already named, is locally of great economical im- 
portance. It is known as the Petrea Coal, the Wellston Coal, and the 
Hill Coal of Jackson county. | 
No discussion of these lower seams is in place here, and no correlation 
of them with the lower coals of other sections of the State has been at-— 
tempted. Numbers have not been assigned to them in the engraved 
chart of the Coal Measures, but their Sub-carboniferous age is there 
asserted in the place that is given them, viz., below the Maxville Lime- 
stone. | 
The position of two other seams above the Wellston Coal, but below the 
Zoar Limestone, is also indicated in the chart, but no mention of them 
will be made here. . 
3. We come now toa horizon that is everywhere conspicuous, for the 
presence of the characteristic elements of the Coal Measure rocks, viz., 
fire-clay, coal, limestone, and iron ore. It is the horizon of the Blue or 
Zoar Limw-stone, and of the Main Block ores. The coal seams associated 
with the limestone can be traced with perfect distinctness through all of 
the marginal counties of the coal field from Pennsylvania to the Ohio 
