188 THE CLAYS OF ARKANSAS. 
In Nevada County, however, no large streams cut deep into the 
soft strata as the Ouachita cuts into those in Ouachita County, so 
that good exposures of the clay beds are rare and little or nothing 
is known about them. The strata of this county are nearly hori- 
zontal but dip slightly toward the southeast, and therefore a good 
clay bed found anywhere in the county will probably lie deeper 
beneath the surface as one follows it southward. 
Records should be made of clay beds passed through by wells, 
for a promising clay found in a well may come to the surface at 
some point farther northwest. It is not likely that good pottery 
clays will be found close to the St. Louis, Iron Mountain and South- 
ern Railway, but valuable and abundant brick clays may be found 
near that road. The best pottery clays and clays available for 
refractory purposes will be found about the central and southeastern 
part of the county. 
Only one establishment in Nevada County is engaged in the man- 
ufacture of clay products, Longston Brothers' common-mud brick 
plant, located at Emmet, with an office at Sutton. 
OUACHITA COUNTY. 
GENERAL GEOLOGY. 
The geology of Ouachita County may be regarded as typical of 
the southern portion of the State. The surface is underlain entirely 
by rocks of Tertiary age except where they have been removed by 
denudation and the valleys filled with Quaternary alluvium or 
residuary accumulations. The Tertiary rocks are usually not very 
hard; they are clays, sands, lignites, and gravels, and these four at 
many places grade into one another, forming sandy clays, clayey 
sands, lignitic clays, and all other possible combinations. At some 
places the sands are indurated, forming hard quartzites; at others 
they are but loose sands; while in color they range through the 
browns, yellows, grays, and reds. 
Though local dips may be seen, most of the rocks lie in horizontal 
or approximately horizontal beds, so that they may readily be traced 
from one locality to another. 
The Tertiary beds have been cut by Ouachita River, which has 
washed out a wide valley. This valley is bordered on the west by a 
rather abrupt escarpment, in which the Tertiary beds outcrop, 
especially at points where the river hugs its right bank, as at Cam- 
den, Newport Landing, and Millers Bluff. 
In Camden a steep-sided ravine having walls 40 feet high is cut 
in the soft sandy clays by the streams A large part of the exposed 
surface of these clays was at one time covered with an abundant 
i The section exposed on the Ouachita at Camden is given in Ann. Rept. Geol Survey Arkansas for 
1888, vol. 2, p. 50. 
