490 GEOLOGY OF OHIO. 
ore is often called “top hill ore” in the region, referring to the position 
of its occurrence, much being found at a considerable elevation above 
the regular ores. It is an ore highly appreciated for its ready reduci- 
bility, though on an average it rarely contains more than 33 per cent. 
of iron. The most considerable deposit is found in the bed of shale 
which usually immediately overlies the limestone seam of ore, and in 
the process of stripping off the shale to obtain the limestone ore, the 
kidneys are separated from the enclosing shale. At different horizons 
above the stratum other accumulations of kidney ore are also found, 
but nowhere is any method applied to their exclusive extraction. 
A few remarks about the manner of obtaining the ores in the 
Hanging Rock region may perhaps be added here with profit. In 
procuring the ores the furnaces draw their supplies almost entirely from 
their own estates, and when they are bought, the ores are valued at about 
50 cents per ton in the ground. ‘The ore beds, as already mentioned, 
have no great thickness, varying from 4 to 18 inches, and thus far, with 
but one or two exceptions, no regular underground mining operations 
have been sustained. On the property of the Hecla Furnace, however, 
considerable quantities have been obtained for several years by drifting 
and by shafts sunk upon the limestone seam. The sections made by 
the valleys through the ore-bearing rocks present continuous outcrops 
of the ore beds, and afford innumerable points of attack. The usual 
mode of obtaining the ores is the very simplest possible, and consists in 
merely digging away the cutcropping rock above the ore beds, and then 
taking up the ore from the bottom of the excavation, or, as it is called, 
benching or stripping. The stripping thus advances regularly, cutting 
away the hill-side and extracting the ore, until the limit is reached, 
when the cost of removing the material over the ore is not repaid by 
the value of the ore obtained. When carefully conducted this limit is 
usually reached when the thickness of the overlying rock is about 12 
feet for a 12-inch seam of ore. 
Fortunately, in this region the rock usually overlying the ore is a 
soft and pretty easily removed clay shale, and in the case of the lime- 
stone ore, the superposed bed of shale contains nodules of clay ironstone 
irregularly distributed, which are separated in the progress of stripping. 
On the great banks of waste thus thrown out in benching, one may ride, 
as on a natural terrace, for miles in and out of the successive valleys, 
and in passing through the region, so far as the eye can reach they are 
