WILCOX FORMATION. 27 
County into Tennessee, and their outcrop through Tennessee and Mississippi is marked by 
a line of stoneware and jug factories. 
The purer white stoneware clays usually occur in large lenses in the coarse variegated 
sands below the Lafayette. In some places these lenses occur far below the Lafayette, 
entirely in the Wilcox sand. In others there is no Wilcox sand above the clay, so that the 
Lafayette rests directly on it. For this reason the clay was thought by W J McGee a, to 
belong to the Lafayette formation. The clay lenses have never been found, however, 
entirely in the Lafayette, but they have been found many feet below the Lafayette entirely 
in the laminated sands of the Wilcox. 
Numerous specimens of fossil leaves are found in the clays used at the potteries at Holly 
Springs and throughout Tennessee. Species of fossil plants collected near Somerville, 
Fayette County, Tenn., by Prof. J. M. SafTord, were determined by Leo Lesquereux. The 
age of the strata in which these fossils were found was said by Lesquereux to be lower or 
middle Miocene. A study of the Tertiary in central and eastern Mississippi and Alabama 
makes it impossible to place the Wilcox in the Miocene. It has been proved by Hilgard, 
Smith, and others that the Jackson, which represents the highest division of the Eocene, is 
much younger than the youngest member of the Wilcox. Not only this, but there are two 
formations — the Tallahatta buhrstone and Lisbon beds of the Claiborne — intervening 
between the upper Wilcox and lower Jackson. 
At Redbanks, on the-Frisco Railroad, Marshall County, is a high ridge, the waters on the 
north side flowing to Chewalla Creek and those on the south side to Redbank Creek. Ero- 
sion along this ridge has been very rapid in places, removing the surficial clays and loam of 
the Lafayette and the yellow loam or Columbia and exposing the white stoneware clays in 
the stratified Wilcox sands. In places erosion has been so extensive that the lenticular 
character of the stoneware clays is easily determined. The material surrounding the clay 
lenses is a coarse, variegated sand, highly cross-bedded. Where not removed by erosion 
the Lafayette and Columbia overlie the Wilcox. 
In sec. 25, T. 3, R. 3 W., the following succession of strata is found, showing the relation 
of the sands to a more siliceous nonplastic clay, which appears in lenticular shape 100 yards 
long and 10 feet thick : 
Section of Wilcox formation in sec. 25, T. 8 S., R. 3 W. 
Feet. 
4. Yellow loam 8 
3. Lafayette 2§ 
2. Irregularly bedded white and yellow sands 10 
1. Red, coarse-grained sand containing layers of ferruginous sandstone; bottom of exposure. In 
this sand the white clay occurs. 
Along the same line to the south, particularly in Lafayette County, there is a greater 
amount of impure, siliceous, and highly stratified clay, which from a distance often has the 
appearance of white chalk banks. There is likewise a less amount of clay occurring in 
lenticular masses. Good workable clay often occurs in horizontally bedded strata. 
The following section, from a deep gully near Sid. Wyley's house, in sec. 16, T. 8 S., R. 
4 W., is typical for this locality: 
Section of Wilcox formation in sec. 16, T. 8 S., R. 4 W. 
5. Yellow loam and Lafayette at surface. Feet. 
4. Impure yellow clay 2 
3. White stoneware clay, horizontally bedded 10 
2. Siliceous ferruginous clay 1§ 
1. Gray and white sand to bottom of gully 2 
Lignite occurs to a greater or less extent throughout the entire Wilcox group, bat it is 
more abundant and purer at certain localities than at others. It seems to be confined to 
local basins rather than to form continuous strata at certain horizons. It is always asso- 
ciated with lignitic clays bearing lignitized wood, leaves, and bark. 
a The Lafayette formation: Twelfth Ann. Rept. U. S. Geol. Survey, pt. 1, 1891, p. 458. 
