128 THE CLAYS OF ARKANSAS. 
LOGAN COUNTY. 
GENERAL GEOLOGY. 
The rocks of the northern half of Logan County belong to the 
upper coal-producing part of the Carboniferous, while those of the 
southern half of the county, except the top of Magazine Mountain, 
lie below the coal. The general geology of the county is like that 
of Sebastian, Franklin, Johnson, and Pope counties, and the clays 
and clay shales are very similar to if not identical with those of the 
counties named. 
CLAY DEPOSITS. 
CLASSES OF CLAYS. 
For convenience of presentation the clays of the county may be 
classified as follows: 
1. Carboniferous clays and clay shales associated with the coal 
and interbedded with the hard rocks. 
2. Buckshot clays or brick loams, found in the uplands. 
3. Terrace or second-bottom clays, found along Arkansas River. 
4. River-bottom clays of the flood plains of the large streams. 
These will be taken up in the order in which they are enumerated. 
CARBONIFEROUS CLAYS AND SHALES. 
Many of the clays associated with the coal beds of Logan County 
are fire clays. Some of these beds are only a few inches thick and 
of limited areal distribution, but it is to be expected that many fire- 
clay beds of workable thickness will be found associated with the 
coal. Such clays underlie the coal in the NE. \ NE. \ sec. 10, 
T. 7 N., R. 26 W., at the coal opening of H. M. Nichols. This clay 
is soft, dark blue, streaked with yellow, and only from 6 to 8 inches 
thick. The miners report that it is not a constant bed. At Wall's 
slope, in the NE. \ NW. J sec. 15, T. 7 N., R. 26 W., a similar clay 
lies beneath the coal bed, but the mine being full of water, its thick- 
ness was not determined. 
On the north side of the NW. \ NE. J sec. 34, T. 8 N., R. 26 W., 
two beds of clay are exposed in the channel of a small stream. The 
upper bed is a dark-brown clay about 3 feet thick; the lower bed 
is of a lighter yellowish color. Only about a foot of the lower bed 
is exposed, but it is probably not less than 7 or 8 feet thick. The 
lower bed is said to have been used as a fire clay. A sample of this 
lower bed has been analyzed: 
