162 THE CLAYS OF ARKANSAS. 
dried too rapidly, and therefore have to be dried in covered sheds. 
The bricks are burned with wood in up-draft kilns. The capacity is 
5,000 bricks a day. The output of bricks is largely governed by the 
local demand. They can not compete with bricks made at Little 
Rock, where convict labor is used in the yards. 
PULASKI COUNTY. 
GENERAL GEOLOGY. 
The northwestern edge of the Tertiary beds crosses Pulaski County 
2 or 3 miles northwest of the Iron Mountain Railway and keeps about 
parallel with it from Little Rock toward the southwest. Northwest 
of this Tertiary margin the rocks of the county are much folded, and 
are either Silurian or Carboniferous, while toward the south and east 
they are nearly horizontal and are Tertiary and Quaternary. The 
granites or syenites of the Fourche Mountain region are of earlier age 
than the Tertiary sediments to the south and east. They furnish the 
kaolins 'of Pulaski County, and have also probably been the source of 
much of the valuable clays of this and of adjoining counties. 
CLAY DEPOSITS. 
DISTRIBUTION. 
But little is known of the details of the distribution of the clays in 
the extreme southern part of the county. South of the Fourche 
Mountain region the land is low and flat, and it is to be expected that 
ordinary brick clays are spread over that part of the county in great 
abundance. In the immediate vicinity of Fourche Mountain there is 
much pisolitic kaolin. 
Pulaski County clays are best exhibited in the southwestern part of 
the city of Little Rock, and extend thence southwestward to the town 
of Alexander, on the Iron Mountain Railway and on the county line. 
Anywhere along this Tertiary margin a section drawn from the Pale- 
ozoic region on the northwest toward the southeast would show 
approximately the same geologic structure. 
FOURCHE MOUNTAIN DISTRICT. 
The feldspathic rocks of Pulaski County cover a total area of 8 or 9 
square miles, all in the vicinity of Fourche Mountain, near Little Rock. 
White clays are found over this same area at various places. They 
also occur in the township next west, in the vicinity of Mabelvale, 
where no feldspathic rocks are known at the surface. The surface 
exposures are in sees. 5 and 9, T. 1 S., R. 12 W., and sees. 2, 10, 11, and 
12, T. 1 S., R. 13 W.; and clays have also been found in wells in sees. 
25, 26, 35, and 36, T. 1 N., R. 12 W. 
