CRAWFOKD COUNTY. 65 
CRAWFORD COUNTY. 
GENERAL GEOLOGY. 
The general geology of Crawford County is similar in the main to 
that of Franklin County on the east and to that of Sebastian County 
on the south. The southern part of the county — a little more than 
half of it — is covered by the upper division of coal-bearing rocks of 
the Carboniferous system. The northern part is made up of rocks 
that underlie the coal-bearing beds. Most of the rocks of the northern 
part of the county dip gently toward the south. The coal-bearing 
rocks are chiefly sandstones and shales, and the valuable clays of 
the county are to be looked for in these clay shales or in the clays 
formed by their disintegration. Other kinds of clays of later age 
that are spread over the lowlands will be spoken of under the head 
of brick clays. 
In sec. 24, T. 9 N., R. 32 W., the following geologic section is 
exposed along Arkansas River in the hills north of the town of Van 
Buren. 
Section in kills norili of Van Buren. 
Feet. 
Gray sandstone on hilltop 20 
Slaty shales 120 
Hard gray sandstone 20 
Dark slaty shales 170 
Sandstone 4 
Dark shale at base. 
Especial attention is directed to this section as showing the 
enormous thickness of the shales of Crawford County in the vicinity 
of Van Buren, on the very banks of Arkansas River. The impor- 
tance of the section and the thickness of the shales will be seen when 
it is realized that many of these shales are available for the manu- 
facture of paving bricks, sewer pipes, and certain fire-clay products 
It should be remembered also that these same beds spread over a 
considerable part of Crawford County. 
One other section may be given as a type of Crawford County 
rocks and their sequence. This section is on the east part of the 
hill in the SW. | sec. 12, T. 10 N., R. 29 W. 
Section in SW. \ sec. 12, T. /<> .V.. R. 29 W. 
Feet. 
Brown sandy shale 15 
Flaggy sandstone 10 
Sandy shales 10 
Thin-bedded sandstone 10 
Sandy shale 5 
Massive sandstone 10 
Concealed 40 
48136— Bull. 351—08 5 
