SEBASTIAN COUNTY, 
209 
This description is doubtless sufficient to show that the clay shales 
of Sebastian County are widespread over the entire county, and 
that the beds are of great thickness. The value or availability of 
each bed has not been determined, but such tests can be made prac- 
tically whenever it becomes necessary to consider the location of a 
manufacturing plant, and a brief examination of the geology should 
show the distribution of the materials. 
POTTERY CLAYS. 
It has already been pointed out that the shales of this region 
break up or decompose under the influence of the weather, forming 
plastic clays. Such clays are available for the manufacture of pav- 
ing bricks and sewer pipe, or for pottery. Clays thus formed are 
about the only ones used for the manufacture of pottery in the upland 
regions of Sebastian County. 
The only pottery clay that was used in Sebastian County in 1889 
came from the S. \ SE. \ sec. 27, T. 7 N., R. 30 W. An examination 
of the geologic structure of the region in which it is found affords 
evidence of its origin and suggests where other and similar clays 
may be found in this county. 
Backbone Ridge 
Little Whiteoak Ridge 
Fig. 18. — North-south section through Biswell Hill. 
The place at which this clay occurs is at the north base of Little 
White Oak Ridge. This ridge runs southwestward toward Green- 
wood and northeastward past Auburn post-office, where it curves 
westward, merges into Butlers Ridge, runs northwestward and ends 
at Butlers Knob, in sec. 10 of this same township and range. To 
the west of Biswell Hill it appears again, striking away to the west 
and southwest, where it is known as Tennessee Ridge. The rocks 
of this line of ridges dip away from Biswell Hill on all sides, and a 
north-south section through Comby's clay pits would expose the 
rocks as they are shown in the section below. 
A section across Little White Oak Mountain, Biswell Hill, and 
Tennessee Ridge would display practically the same structure as that 
shown above. This structure explains the origin of the Comby 
clays and suggests at the same time that similar clays may extend 
along the northwest side of Little White Oak Ridge, the southwest 
side of Butlers Ridge, and the south side of Tennessee Ridge. 
The example cited above is given for the purpose of illustrating 
the general features of the geologic structure of Sebastian County and 
48136— Bull. 351—08 14 
