12 GEOLOGY AND MINERAL RESOURCES OF MISSISSIPPI. 
with the much later Cretaceous deposits, which conceal the Chester except where vigorous 
erosion has removed them. 
The southernmost outcrop of the Chester limestone in Tishomingo County is at the old 
McDougle mill, on the headwaters of Mackys Creek. 
No coal occurs in the Carboniferous rocks of Mississippi, as the Coal Measures do not out- 
crop within the limits of the State. 
CRETACEOUS* 
TUSCALOOSA FORMATION. 
Between the uppermost member of the Carboniferous and the next overlying formation in 
northeastern Mississippi there is a marked unconformity. The overlapping formation, which 
is well shown near Tuscaloosa, Ala., has been called the Tuscaloosa. 
In its lower part this formation is composed of dark-colored clays, thin seams of lignite, 
lignitic clays, and variegated sands and chert, and in the upper part of light-colored clays. 
The clays of the lower part are very compact, giving rise to numerous bold springs along the 
valleys where the clay has been cut into by the streams and is overlain by Lafayette sands 
and gravel. These clay horizons are often associated with beds of lignite and less pure clays 
which contain impressions of leaves and bits of lignitized wood. Where free from impurities 
the clay often forms a white to gray plastic material well adapted for making common jug 
ware. In places in Tishomingo and Itawamba counties the clay approaches a kaolin in 
appearance and purity and is used for making pottery. 
Higher up in the formation the strata become more sandy in character, though there are 
more or less irregular beds of clay extending throughout the formation. The sands are irreg- 
ularly bedded with a less amount of clay. It is impossible to trace any one horizon of sand 
or clay for any great distance. Along some of the larger streams, where good exposures are 
obtained, the material often changes within a hundred feet from a laminated clay to cross- 
bedded sands. There is more or less mica found throughout the formation in both the sands 
and clays. 
The sands of the Tuscaloosa are, in places, of an Indian red color, and where they come 
into contact with the overlying Lafayette it often becomes impossible to separate the two 
formations. In other places the color changes from various shades of yellow to the many 
hues of red and purple. The sands are highly cross-bedded, as shown in PI. II, B. 
The thickness of the formation in western Alabama is estimated at 1,000 feet. It thins 
perceptibly to the north. At Corinth, Miss., the hard Paleozoic rocks of the old sea floor were 
found in the city waterworks well at a depth of 450 feet, and the upper sands of the Tusca- 
loosa at 180 feet, thus making the entire thickness of the formation in northern Mississippi 
but 270 feet. Still farther north, in Tennessee, the entire thickness of the Tuscaloosa and 
the next overlying formation, the Eutaw, taken together and described under the name of 
Coffee sands, is given by L. C. Glenn as 300 feet. 
The area occupied by this formation is a long, irregular band 5 to 15 miles wide, extending 
north from the Alabama line due east of Columbus to the Tennessee boundary, including the 
northeastern portion of Lowndes, the eastern half of Monroe, and a narrow strip along the 
eastern portion of Prentiss and Alcorn counties, and overlapping the Paleozoic rocks in 
Tishomingo and northern Itawamba counties. Tombigbee River approximately marks the 
western boundary north of Monroe County, and southward to the Alabama line the western 
boundary lies within 3 to 8 miles east of the river. 
In northern Tishomingo County the character of the lower part of the formation is shown 
in a well on Bascom Whitehurst's farm on the west side of Yellow Creek, in T. 1 N., R. 10 E. 
The section of this well showed 10 feet of surface red clayey sand and gravel belonging to the 
Lafayette; It) feet of yellow sandy clay; 10 feet of white clay, very pure; 14 feet of black 
lignitic clay containing wood, "charcoal," and a large amount of pyrite nodules. The well 
stopped in white clay at a depth of 65 feet before reaching the hard Paleozoic rocks, which 
outcrop at the foot of the hill about 100 feet below the top of the well. 
The same dark-colored clay interbedded with white clay occurs on the Iuka and Mingo 
road at Crippledeer Creek. On the north side of the creek the following section is shown: 
