GEOLOGIC AGE AND GEOGRAPHIC DISTRIBUTION. 39 
by the fossil plants peculiar to the beds themselves. Marine fossils 
of Eocene age have been found east of the outcrops of the clays, 
however, at Warren, in Bradley County; at Monticello, in Drew 
County; at Bison, Kingsland, and about New Edinburgh, in Cleve- 
land County; and at White and Red Bluffs, on Arkansas River, in 
Jefferson County. The pottery clay beds of Saline and Hot Spring 
counties seem to dip beneath the fossil-bearing beds mentioned 
above, and must therefore be not later than Eocene. For these 
reasons these beds are spoken of in this respect as being of Ter- 
tiary age. 
With this understanding of the general characters, age, and origin 
of the common Tertiary pottery clays of the State we may take up 
the details of their occurrence. 
The Tertiary clays are the most important in the State of ArKansas. 
As already stated, they, with their accompanying sands, marls, and 
organic deposits, underlie a large part of the State east and south 
of the St. Louis, Iron Mountain and Southern Railway south of 
Arkansas River. North of this and east of the Paleozoic lulls the 
sediments are chiefly Quaternary deposits, except Crowleys Ridge, 
the lowest part of which is Tertiary. Most of the beds of this series 
were laid down in the sea when it extended over all of southern and 
eastern Arkansas and as far north as the mouth of Ohio River. The 
sediments that were washed into this Tertiary sea sloped gently 
toward the middle of the gulf, and the hardened beds they formed, 
now lifted above sea level, still retain that slope. During Tertiary 
time the land must have risen from beneath the water more than 
once, for we have at many places beds of lignite that could be formed 
only as swamp deposits. After the lignites had been formed the 
land was again depressed and covered by the sea and the accumu- 
lation of sediments continued. Everywhere over the area those 
sediments were laid down in beds that were approximately horizon- 
tal but dipped gently seaward. After the final elevation of these 
beds above the sea, the streams carved out our present topography 
in the uppermost of the Tertiary beds. 
From this brief sketch it will be seen that the sediments laid 
down during Tertiary time vary from place to place in thickness and 
in character, just as any marine sediments of the present time vary. 
Some of the beds are clays and some of them are sands and gravels. 
The fresh-water or land deposits also vaiy, just as such deposits 
vary at the present time. 
The fire clays of the Crowleys Ridge region are everywhere asso- 
ciated with beds of Tertiary lignites, which outcrop in the basins 
of several of the larger streams. Lignites and fire clays occur in 
the NE. J NE. } sec. 26, T. 4 N., R. 4 E.; NW. J SW. \ sec. 8, T. 
