72 THE CLAYS OF ARKANSAS. 
The bed of the creek one-half mile north of the above locality is 65 
feet below the top of the Tertiary beds in the above section. The Ter- 
tiary strata of the section at the creek for 30 feet above the water, 
forming a continuous section with the one given above, consist of dark- 
blue clay interstratified with coarse sand, which contains large iron 
concretions 1 foot or more in diameter. Besides the iron there are 
numerous smaller lime concretions. The blue clay where exposed in 
the bluff sloughs off in large, vertical slabs. It contains more or less 
mica, selenite, and alum salts. Thickness, 30 to 35 feet. 
On the west side of Crowleys Ridge the slope is more gentle and the 
Tertiary strata are covered by talus from the ridge. The surface ma- 
terial in the adjacent level land is gray to yellowish sandy clay, which 
is used for brick manufacture. In the town of Wynne this surface 
clay is penetrated in the wells at a depth of 40 feet. 
CLAY DEPOSITS. 
The most important clay in the county is the common brick clay. 
The loess and yellow loam on the top and the west slope of Crowleys 
Kidge form an inexhaustible supply of common wet-mud and pressed- 
brick clays. 
One mile east of Wynne the following section in the railroad cut 
shows the variation in the color and character of the loess : 
Section in railroad cut 1 mile east of Wynne. 
Feet. 
Light-gray to buff loess 10 
Reddish loess containing fine sand 20-30 
White loess with more or less scattered pebbles and sand 5-10 
The reddish loess would doubtless be better adapted to the manu- 
facture of brick than the upper or lower layer. It contains a large 
amount of iron oxide and would burn to a bright red. Where the 
calcareous loess is used without mixing it with sandy clays there is 
great danger of getting the bricks too soft by adding too much water. 
There is a bed of good sewer-pipe and tile clay at the base of a sec- 
tion in the Tertiary of Cross County near the village of Cherry Valley. 
The locality is in the NE. J NW. \ sec. 23, T. 9 N., R. 3 E. m The clay 
is exposed in the bottom of the creek to a depth of 3 feet, and extend 
downward to an unknown depth. It is a fine light-drab clay, unctu- 
ous to the touch and apparently suited to the manufacture of sewer 
pipe. It is more like potter's clay than any other clay that has been 
found in the Crowleys Ridge country. There is a similar deposit at 
the base of the section exposed at Double Head Bluff in St. Francis 
County, near the water level. The locality is in the NW. \ NW. \ sec. 
18, T. 5 N., R. 4 E. It is much thicker here than at Cherry Valley, 
on the opposite side of Crowleys Ridge, and it is possibly identical 
with it. Neither of these clays are fire clays and could not be success- 
fully used for fire brick. 
