22 GEOLOGY AND MINERAL RESOURCES OF MISSISSIPPI. 
This limestone is sufficiently pure for making lime, and is used locally for building pur- 
poses. The strata below the ledge of limestone are covered with the wash of the hillside, 
and the thickness can not be determined. 
South of Ellistown the blue calcareous clay which perhaps belongs to the Selma appears 
up the hillside 25 feet above the bottom land to the east. 
TERTIARY. 
MIDWAY GROUP. 
CLAYTON FORMATION. 
The lowest division of the Tertiary is represented in Mississippi by a series of hard crys- 
talline limestones and calcareous sandy marls, belonging to the Clayton. The limestone 
of this formation was referred by Hilgard to the Ripley. More recent investigation, how- 
ever, by Harris, Aldrich, and others has, on paleontologic grounds, placed the limestone in 
the lowest division of the Tertiary. 
The Clayton formation in Mississippi is represented by about 30 to 40 feet of limestone 
and 30 feet of sandy marl. Owing to the limited area of the Clayton and the lack of detailed 
work across the State it has been mapped with the overlying Porters Creek clay, which is 
shown as a narrow belt extending from Alabama to Tennessee and lying between the Rip- 
ley and Selma on the east and the Wilcox on the west. The name Midway is given to the 
group from the type locality at Midway, Ala. 
The Clayton is well shown in Tippah and Union counties, where it has received the most 
detailed study. In lowest member is a hard blue limestone containing a large number of 
fossils, the most prominent of which is Turritella morioni. For this reason this rock has 
been called the Turritella limestone. On Mr. Bobo's place, 1£ miles north of Chalybeate, 
the Turritella rock is little more than a conglomerate of angular fragments of gray, white, 
and yellow limestone cemented together. Turritella fossils make up a large part of the 
limestone. Throughout the whole mass are small, rounded, and often glazed iron pebbles 
reaching one-fourth inch in diameter. This limestone rests on the dark-blue "Owl Creek" 
marl of the Ripley and is overlain by a yellow sandy marl. The hard persistent Turritella 
rock is found in numerous blanches in the vicinity of Chalybeate and southward to Ripley. 
Two and a half miles east of Ripley it forms in places small bluffs along the streams. 
The Clayton limestone outcrops on the south side of Ripley Creek one-half mile south of 
Ripley. The same ledge occurs along the creek for 1 mile or more to the east. It is here 
underlain by a yellow, highly micaceous, arenaceous marl containing a few badly preserved 
fossils. The yellow color is due to oxidation by surface agencies, for a few feet below the 
surface the color becomes a dark blue. 
One-half mile east of the bridge across Ripley Creek south of town the Turritella lime- 
stone of the Clayton forms a bluff 20 to 40 feet high. The following section gives the rela- 
tion of the materials immediately overlying the Turritella rock: 
Section of Clayton formation near Ripley. 
Ft. In. 
4. Lafayette capping hill. 
'A. Thin stratum of green calcareous sandstone, very hard and containing large flakes of mica 
and few fossils 2 2 
2. Yellow micaceous sand 30 
1. Turritella limestone 15 
No. 1 of the above section is found in the wells at Ripley from 10 to 35 feet below the 
surface. At the mill in the bottom on the east side of town a well recently dug has the 
dark-blue "Owl Creek" marl on the dump. The yellow sand overlying the Turritella rock 
is very persistent and is easily distinguished from the overlying Lafayette where the latter 
is present. When damp the yellow sand has a slight greenish tinge. This sand is present 
along many of the streets of Ripley, especially on the lower streets near the depot. In the 
northern part of the town, near the "city limit," the greenish-yellow sand outcrops on 
