COAL MINING. 317 
THE Onto CoAL FIELD. 
The great Appalachian Coal Field, the largest known coal field in 
the world, of which the Coal Measures of Ohio constitute a part, extends 
through portions of nine different States, viz., Pennsylvania, Maryland, 
West Virginia, Virginia, Kentucky, Ohio, Tennessee, Alabama, and 
Georgia, and occupies an area which has been variously estimated at 
from 50,000 to 58,000 square miles. From 10,000 to 12,000 square 
miles of this area are situated in Ohio. More than one-fourth of the 
State is therefore underlain with coal bearing strata. The western mar- 
gin of the Ohio portion of the great coal field runs through the coun- 
ties of Trumbull, Geauga, Portage, Summit, Medina, Wayne, Holmes, 
Knox, Licking, Perry, Hocking, Vinton, Jackson, Pike, and Scioto, 
and the Coal Measures are spread over all the territory lying east of 
this line of outcrop to the state line at the Ohio river. 
On the margin of the Coal Measures of Ohio in the above named 
counties, there is only one workable vein of coal met—the lower seam, 
or Coal No. 1 of the geological nomenclature ; and owing to the pecu- 
liar conditions under which this coal was formed, it is often wanting 
where the practical miner, unacquainted with the peculiar irregularities 
under which the coal was deposited, would unhesitatingly assert its 
existence. The coal strata dip at the rate of about 30 feet to the mile, 
in an easterly direction (the line of dip being south 65 east), and the 
lower coal which crops out on the western flank of the coal measures of 
the State is carried 1,500 to 1,600 feet below the highlands in the coun- 
ties of Belmont, Monroe, Washington, and Meigs, on the Ohio river. 
The dip of the strata is irregular, being at some points as high as 80 or 
100 feet to the mile, while at other points it is not more than 10 or 20 
feet to the mile. Frequently reverse dips are met, causing the strata to 
form a series of synclinal and anticlinal waves. 
The Coal Measures of the State are divided into 3 series, namely : 
‘“‘’The Lower Measures, the Barren Measures, and the Upper Measures.” 
The lower measures are about 500 feet in thickness, the barren meas- 
ures 400 to 500 feet, and the upper measures 600 feet thick. All the 
beds of coal in present course of development are drawn from the upper 
or lower coal measures, the barren measures, as the name indicates, con- 
taining little coal of sufficient thickness for the immediate purposes of 
the miner. 
The coals now being worked are mainly drawn from four or five 
