38 GEOLOGY AND MINERAL RESOURCES OF MISSISSIPPI. 
An interesting feature of the fornication is the fact that outliers, several miles removed 
from the main body of the formation, have been recently discovered. They occupy some 
of the highest land along the divide between Big Black and Pearl rivers, in the southern por- 
tion of Madison County. There are also two outliers at but a short distance from the main 
body of Vicksburg, one near Tinnin and the other near Brownsville. The details of the 
formation have been more thoroughly studied between Pearl and Big Black rivers than at 
any other locality. A careful study of the formation across the State would doubtless reveal 
a large number of outliers. 
The localities of the Vicksburg outcrop across the State are numerous. There are in this 
formation a few hard strata of blue limestone, which resist the weathering agents, and 
where the country is somewhat hilly this hard limestone is almost always found at or near 
the surface (PI. II, A, p. 12). 
The most complete serf inn of the formation at any one place is in the bluff at Vicksburg, 
given by Hilgarda as follows: 
Section of the bluff at Vicksburg. 
Feet. 
7. Bluff formation (loess) 10-20 
6. Orange sand (Lafayette) 5-20 
5. Alternating strata, 1 to 6 feet thick, of limestone and marl, containing the Vicksburg fossils and 
some 1 lands of noneffervescent gray sand and clay 60-65 
1. Black lignitic clay and gray sand, with Ostrea gigantea, Corbula alta, Natica mississtppiensts, 
Cytherea sobrina, Madrepora mtssissippiensis 5 
3. Gray or black lignitic clays and sand with iron pyrites, exuding salts and sulphureted hydro- 
gen 25 
2. Solid lustrous lignite, with whitish cleavage planes 3 
I. White limestone of the Jackson group? S 
All above No. 1 Ililgard places in the Vicksburg. 
To show the alternating character of the limestone and marl an additional section is given 
below of the bluff about hallway between the cemetery and the city: 
Section of the bluff near Vicksburg. 
Inches. 
22. First stratum of limestone from top; overlain by loess 10 
21. Gray to yellowish marl 9 
20. Heavy-bedded limestone 46 
19. Indurated marl 34 
18. Thin, calcareous, plastic clay 2 
17. Indurated marl 6 
16. Clay similar to No. 18 2 
15. 1 ndurated marl 5 
14. Clay 4 
13. Hard limestone 18 
12. Clay and marl from one-half to 2 inches thick 15 
II. Indurated marl 21 
10. Limestone 18 
9. Gray marl 18 
8. Limestone 18 
7. Marl 3-6 
6. Hard limestone 52 
5. Marl 6 
4. Limestone 27 
3. Marl 17 
2. Limestone 20 
1. Marl 45 
This exposure is characteristic of the Vicksburg throughout the State. In places the 
limestone is more abundant, and in other places the marl. The limestone is more commonly 
found on account of the ease with which the marl breaks down into soil. In fact, the marl 
is rarely found except on bluffs, in wells, or on hillsides where erosion has been very rapid. 
a Geology and Agriculture of Mississippi, 1860, p. 141. 
