664 GEOLOGY OF OHIO. 
18 feet wide; no prups are used, and the pillars are left 40 feet thick of 
solid clay. 
The next clay met in the ascending series is the Brookville clay, 
which is a serviceable one in several places. At Navarre, Stark county, 
an extensive bank is worked. The clay underlies the Brookville coal 
(coal No. 4 of Newberry), which is in turn overlaid by the Putnam Hill 
limestone beds. The clay is quite silicious, but makes a good No. 2 
brick. It is mined by drifts. To the south of Dover, in the Tusca- 
rawas' Valley, this clay is always present, and often of good quality. It 
is mined near New Philadelphia and below in several places, and used 
at the brick-works. At Roseville, Perry county, the center of the 
second largest stone-ware district of the State, the clay used is a mixture 
from this horizon and that of the Kittanning clays. The lower clay is 
quite sandy, and light in color; it is found separated by sandy beds, 
and shales 21 feet thick from the gray or Putnam Hill limestone. It 
is possible that it represents the horizon of the Tionesta coal instead of 
the Brookville. It is mined in several localities near by, and is usually 
only 3 or 4 feet thick. 
The next coal horizon, that of the Clarion coal, is poorly repre- 
sented in this State; clay from this level is used at but a single point, 
viz., Robbinsville, Columbiana county. ‘The clays of the Scrubgrass 
coal, which underlies the Ferriferous limestone, are utilized in Lawrence 
county. The clays are sometimes hard and flinty, but usually are 
second grade. They are mainly applied to fire-brick manufacture. 
Just above the Ferriferous limestone, in Lawrence county, directly on 
top of the limestone ore, occurs a massive deposit of so-called white- 
wash clay, which marks the level of the ore on every hill for miles 
around. The clay is dug and thrown off to get the ore, and the weather- 
ing agencies soon give it the peculiar white appearance from which it 
derives its name. The deposit changes character to the southward, 
and at Ironton appears frequently as a flint clay. ‘The clays over- 
lying the limestone, shade off into a shaly band, which separates them 
from those of the Kittanning formation. ‘The distance from the lime- 
stone to the coal is only eighteen or twenty feet, and the space is often 
filled with various grades of clays belonging to both levels. The limestone 
clay is used for brick, pottery and pipe, to some extent. This locality 
presents an inexhaustible supply of clay, amply good enough for any 
second class work; mixed with hard clay, good enough for any use. 
