YELL COUNTY. 231 
CLAY DEPOSITS. 
CARBONIFEROUS CLAY SHALES. 
In Yell County the great shale member at the top of the Atoka 
formation is again one of the most prominent and important of the 
Carboniferous rocks. This shale enters Yell County -on the west, on 
the south side of Magazine Mountain 2\ miles west of Waveland, 
and extends along the south side of both Magazine and Chickahah 
mountains. At the east end of Chickahah Mountain it runs round 
the end and then, turning westward, extends along the base of the 
ridge until it joins the same outcrop around the base of Huckleberry 
Mountain. The same beds run entirely around Three Knobs Moun- 
tain, around Spring Mountain, and around Mount Nebo. The shale 
bed underlying the sandstone on the south side of Dardanelle Ridge 
is this same shale. 
Shales lower in the geologic scale are exposed over a large part of 
Yell County. At Chickahah village and in the valley thereabout 
there are many exposures of such shales. At Danville shales are well 
exposed along Petit Jean Creek with a dip N. 60° W., varying from 
20° to 24°. These shales extend over the flat valley for miles east 
of Danville. On the Rover road south of Danville and on the north 
side of Danville Mountain there are many exposures of clay shales 
interbedded with sandstones, and these alternations of shale and 
sandstone continue to the top of Danville Mountain. Along the 
road running from Danville to Ola, along the base of the mountain, 
the rocks are nearly all shales and all dip toward the north. At Ola, 
on the Choctaw Railway and just south of the railroad station, is a 
cut, 12 feet deep, in shales. A few hundred feet west of the station 
there is a large exposure of promising looking shales in the railroad 
cut. Along the road leading from Ola toward Dardanelle shales are 
exposed at many places for a mile or more, all of them dipping 
northward. Where the Ola-Dardanelle road crosses Petit Jean Creek 
the flaggy shales dip N. 80° E. at an angle of 14°. On the ridge a 
mile north of Dardanelle the red clay is underlain by fissile shale 
dipping north and passing beneath Dardanelle Rock. 
BRICK LOAM AND BUCKSHOT CLAYS. 
The brick loam or yellow and ashen buckshot clays cover a large 
area in the lowlands of Yell County; indeed, there is probably more 
clay of this kind in Yell than in any other county in the State. The 
clays are especially abundant and thick along Petit Jean Creek 
from the point where that stream enters the county, 3 or 4 miles 
southwest of Waveland, to the place where it empties into Arkansas 
River — a distance of about 50 miles. In places south of Dardanelle 
the yellow loam is exposed to a depth of fully 12 feet, yet the total 
thickness of the deposit is not visible. 
