170 THE CLAYS OF ARKANSAS. 
LITTLE ROCK DISTRICT. 
BRICK CLAYS 
The folded Paleozoic rocks pass beneath the city of Little Rock, and 
on these folded beds rest the Tertiary clays and sands of the south- 
western part of the city. It should be observed also that these Ter- 
tiary oeds are nearly horizontal, that they thin out toward the north, 
and that similar beds underlie the region south of Fourche Moun- 
tains. 
At several places in the city of Little Rock the folded Paleozoic 
rocks may be seen standing almost on end. The famous " little rock " 
itself, on which rests the south end of the railway bridge at the foot 
of Main street, is a folded and wrinkled Paleozoic bed. 
Only a few paces south of the river bank these older beds are not 
exposed, but the surface is made up of loose materials. One of the 
best sections seen near the center of the city was exposed when the 
excavations were made for the foundations of the Masonic Temple, 
on the corner of Fifth and Main streets, in June, 1890. The section 
exposed was as follows: 
Section in excavation for Masonic Temple at Little Rock. 
Feet. 
1. Mottled red clays with chert pebbles, becoming more sandy at 
the base 7-9 
2. Reddish-brown clayey sand with brown chert pebbles 2-3 
3. Red , gray, and white mottled plastic, sandy clay with a few large 
and angular sandstone fragments at the top of the bed 
(exposed) 3 
The upper surface of* No. 3 is irregular, as if it had been eroded 
before the overlying beds were laid down upon it. These are proba- 
bly the overwashed portions of the Tertiary series, the equivalents 
of which on the Atlantic seaboard are called the Appomattox forma- 
tion. These rehandled beds of mottled clays, sands, and gravels 
are found at the surface in nearly every part of the city. They are 
well exposed in the cuts, even on the top of Capitol Hill, in the vicinity 
of the school for the blind, and at many other places. Below these 
gravelly beds lie the undisturbed Tertiary strata, which in and about 
Little Rock consist chiefly of limestones, shales, or clays, and sands. 
Mr. C. E. Siebenthal, while in the employ of the Arkansas Survey, 
collected many data regarding the geology of southwestern Little 
Rock. He is of the opinion that there are four pretty constant and 
well-defined beds in the series of sediments resting upon the Paleozoic 
rocks. These are, beginning at the base, (1) yellow calcareous clay 
or marl; (2) dull gray fossiliferous limestone; (3) soft, dark unfossil- 
iferous shale; (4) olive-green clay, probably derived by weathering 
from No. 3. Above this type section are found various combinations 
of sands and gravels and soil. 
