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380 GEOLOGY OF OHIO. 
class that attains any great importance in iron making in Ohio, and 
this one stands at the he.d of the list of all Ohio ores. It is known as 
‘‘ Limestone ore” in the southern counties, and as the Baird ore in 
Hocking and Perry counties. Upon it the charcoal iron industry of 
Ohio has been established and maintained. 
The places of these several ores in the geological scale have now 
been pointed out. It will be seen that they are distributed throughout 
the entire Lower Coal Measure series, from bottom to top, being found 
at not less than 12 distinct horizons, which are shown below: 
Upper Freeport coal. 
Upper Freeport clay. 
Upper Freeport limestone. 
Lower Freeport limestone. 
Kittanning shales. 
Ferriferous limestone—2 or more separate deposits. 
Putnam Hill limestone. . 
Upper Mercer limestone. 
Interval between Mercer limestones. 
Above. 
Lower Mercer lim n 
estone Below. 
Interval between Mercer and Sharon Groups. 
Sharon coal. 
GEOGRAPHICAL DISTRIBUTION OF THE IRON 
ORES OF OHIO. 
The ores of the first section, viz., the stratified ores, are worked at 
the present time in the seven counties named below: 
Trumbull, Tuscarawas, 
Mahoning, Perry, 
Stark, Scioto. 
Carroll, 
The blackband of the Sharon coal horizon is worked in Trumbull 
and Mahoning, and to a trifling extent in Scioto county. The black- 
band of the Upper Freeport coal horizon is worked on a large scale in 
the four remaining counties of the list. 
