872 GEOLOGY OF OHIO. 
foot seam,” but it reaches a thickness of 4 feet 10 inches for its 
maximum, and carries 43 feet through considerable territory. The basin 
originally included about 800 acres above drainage, as nearly as it can be 
judged from the exterior boundaries. The coal thins down abruptly on the 
northern margin of the basin. It is not found thick enough for mining 
north of the Baltimore and Ohio Railway, and it does not crop out in 
the river bluffs. The valley of Mill Run affords the best access to the 
basin, and most of the mining in the seam has been carried on here. 
South of this valley the coal is cut out abruptly by a heavy sandstone. 
South of Zanesville, in the river hills, the Lower Kittanning coal 
nowhere appears, though its companion seam is everywhere present and 
worked. At the horizon where the lower coal is due, a buff limestone 
bearing an ore and also a bed of fire-clay is often found. This series 
is also well shown on Putnam Hill, opposite Zanesville; the limestone 
is here 27 feet below the Middle Kittanning, or No. 6 coal. The lime- 
stone is fossiliferous, and contains well-preserved forms, among which 
large bivalve shells are especially noticeable. Reference has already 
been made to it on page 97, and the suggestions there offered as to its 
place in the series are the best that present knowledge warrants. 
The coal of this basin, so far as it has been worked, is a two or 
three-benched coal. The main parting, and sometimes the only one, is 
a sulphurous band, two or three inches thick, and 18 or 20 inches from 
the top of the seam. Nodules of pyrites are often found near this 
parting also. Ata little less than a foot from the bottom, a “ bearing- 
in” slate is often found. The seam is mined by undercutting and blast- 
ing, one pound of powder being expected to bring down 20 tons of 
properly prepared coal. Rooms are worked 15 feet wide. There is 
often found a thin band of slaty coal at the top of the seam, which is 
taken down and sent out with the balance. The irregularities in the 
seam occur mainly in the bottom. | : 
The coal is sold in Zanesville exclusively, all of the mines depend- 
ing on carts and wagons for the distribution of their products. The 
seam is applied to all ordinary uses. It is preferred by many for house- 
hold use to the coal of the upper seam, as it holds its fire longer. It is 
used quite largely by the Ohio Iron Company as a-milling fuel, and it 
is also used as a steam coal to some extent. Itis, asa rule, sold at a 
lower price than the upper coal. 
Its composition, as sampled from Harper’s bank for the survey by 
Mr. E. C. Downerd, and analyzed by Professor Lord, is as follows : 
