THE IRON ORES. 373 
No iron ore occurs in the next succeeding member of the Ohio 
scale, viz., the Lower Helderberg limestone, nor is any known in either 
the Devonian limestone or the Devonian shale, but springs issuing from 
the latter sometimes form considerable deposits of bog ore. In the great 
Waverly Group of Sub-carboniferous age, more favorable conditions for 
iron production occur, and we begin to find ore segregating from the 
clays and shales in distinct horizons. None of these accumulations, 
however, is regularly mined in the State, and none, so far as known, has 
ever been mined, except in occasional trial pits. The seams are at once 
uncertain, thin, and of doubtful quality. The only localities where any 
attempts are made to obtain ore from the Waverly Group is in the 
vicinity of the westernmost furnaces of the Hanging Rock district. 
Here all horizons that promise supply are tested, and, among others, 
these unlikely sources of iron are occasionally tried. 
The Sub-carboniferous limestone, which is sparingly developed, 
and more sparingly worked in Ohio, carries a block ore of approved 
quality on its upper surface, and occasional kidneys of ore in the clays 
above it. This ore has been worked to a small extent in Scioto, Jack- 
son and Perry counties in connection with the limestone which supports 
it. Wherever the latter has been worked for furnace flux, a little of 
the ore has been brought out with it, but at the present time other lime- 
stones have entirely supplanted these thin and impure beds of Sub- 
carboniferous age. That the ore is not a strong or persistent body is 
evident from the fact that all production of it ceases with the working 
of the limestone. | 
The Carboniferous Conglomerate that comes next in the scale is an 
iron bearing horizon, to a limited extent. There is often a sheet of ore 
of a few inches in thickness intermixed with the pebbles of its upper 
surface. The coarse and worthless ore, once mined at Scioto Furnace 
under the name of the Guinea-fowl ore, belongs to the Conglomerate 
horizon, but no valuable deposit has been found in this formation, and 
none is likely to be found. 
The iron ores now mined in Ohio belong without exception to the 
division next reached in ascending the geological series, viz., the Lower 
Coal Measures. The discussion of this group of ores will occupy the 
present chapter. Before entering upon it, however, brief mention will 
be made of the two remaining sections of the Ohio scale, viz., the 
Barren Measures and the Upper Coal Measures, which will be treated 
together. | 
