52 THE CLAYS OF ARKANSAS. 
of the Si ale lying south of the Ouachitas or novaculite ridges of 
Pulaski, Saline, Hot Springs, Montgomery, Pike, and Polk counties. 
The quartz of the pebble beds is doubtless derived from the same 
region, for the novaculite shales are noted for the great number of 
thin quartz veins they contain. The fact that the pebbles generally 
underlie the silts and alluvial beds of the flood plains of the streams 
shows, too, that they are older than these silts. They seem to have 
been brought to their present position at the time when the Tertiary 
land was emerging from the bed of the sea, having been spread out 
by the undertow of the retiring waters. 
These gravels are most abundant on the tops of the highest hills 
of the region, where they make excellent roads, or beneath the soils 
along streams. This is because they were originally spread over an 
approximately flat region; subsequent erosion has removed some 
of this material, thus making valleys in which the gravels are con- 
centrated beneath the silts and soils that have later accumulated 
above them. 
CLAY DEPOSITS. 
Beneath the gravels and immediate surface soils lie the soft Ter- 
tiary beds referred to as cropping out in the bluffs of the Ouachita. 
These deposits contain many beds of pottery clay. Only a few of 
the outcrops of these beds can be noted here, but anyone who will 
bear in mind the general geologic structure of the region, as stated 
above and as shown in the section on page 17, can readily trace 
the beds and will know where to look for these clays when they have 
been found at a single locality. 
About 3^ miles north of Hampton, at a point where the Hampion- 
Chambersville road crosses Rocky Branch, on the slope of a hill 
about 150 feet south of the stream, is a bed of greenish-gray potter's 
clay. It is not well exposed and neither its upper nor its lower limit 
could be seen when the place was examined, but it appears to have a 
thickness of about 4 feet. It can not be stated positively that the 
clay exposed is in place, but if it is the bed will be found to continue 
both up and down Rocky Branch at the same elevation, and it is 
quite probable that it may be found also on the north side of this 
stream at about the same elevation. 
About 3 miles south of Chambersville, just south of Whitewater 
Creek, at a place where the Hampton-Chambersville road ascends 
about 40 feet from the bottoms to the higher land, probably in the 
SW. I sec. 3, T. 12 S., R. 13 W., potter's clay is exposed in the face 
of the hill in the road. The thickness of these beds can not be 
determined without digging, but they seem to be from 10 to 20 feet 
thick at the place mentioned, and are well above all possible overflow 
of the neighboring streams. The outcrop extends around the face 
of the hill to the northeast and southwest from the road, while the 
