334 GEOLOGY OF OHIO. 
2. IRoN ORES oF COLUMBIANA COUNTY. 
The ore production of Columbiana county stands by itself among 
the mining interests of the State. Nota pound of ore is taken directly 
from the horizons that supply it, but the ore mining of the county is 
altogether placer mining. ‘The gravel beds that fill the valley of the 
Middle Fork of Little Beaver constitute the present available ore 
deposits of the county. These gravel beds are dug over and sifted, 
and the ore is selected from the other materials by hand picking. 
The ores of this county all belong to the class of kidney ores. 
They are chiefly derived from two horizons, but additions are made 
from two others, to a small extent. The main horizons are (t) the 
Kittanning shales, 2. e., the shales between the Middle and Lower 
Kittanning coals, and (2) the Ferriferous limestone. The subsidiary | 
sources are scattering kidneys that are found with or near the Freaport 
limestones, both of which are well developed in the county. 
These horizons can be arranged in tabular form, as follows: 
Upper Freeport limestone. 
Trtervallteaiicecscace eee cetacean aeons orca Meena 30 to 50 feet. 
Lower Freeport limestone. 
Tnntenvall ens fie. Pacestecse meee PARAL Dan eee ee 70 to 90 feet. 
Kittanning shales. 
TREO VALS Yee diccrcwctars Mose ae eae oe Saree eee Pre oa hay See ein ramraured sens 25 to 40 feet. 
Ferriferous limestone—Coal No. 3 at Leetonia. 
The two main horizons will be recognized as among the most 
important and widely extended sources of ore in the Lower Coal Meas- 
ures. The first named is in fact the largest source of kidney ore in the 
State. It produces the “shell ore” of Tuscarawas and Stark counties, 
the Snow Fork kidney of the Hocking Valley, the Black kidney of 
Lawrence county, and the Red kidney of Northern Kentucky. The 
second horizon is by all odds the most important single source of iron 
in the Lower Coal Measures. It is the Clarion and Wampum ore of 
Western Pennsylvania, on which the old charcoal iron manufacture of 
that State was based. It is the limestone ore of the Hanging Rock 
district, and the Baird ore of the Hocking Valley, on which the char- 
coal iron manufacture of Ohio was and is almost entirely dependent. 
In both Pennsylvania and Ohio, however, the ore derived from this 
source is no longer confined to charcoal iron-making, but it has become 
