42 GEOLOGY AND MINERAL RESOURCES OF MISSISSIPPI. 
to the southeast, crossing the Illinois Central Railroad between Terry andByram. Th< 
line then turns northeastward, passing through Monterey to Brandon, at which point it 
finally assumes a southeasterly direction, continuing thence through Daniel, Raleigh, Voss- 
burg, and Waynesboro into Alabama. All of the State south of this line, except a narrow 
belt of Port Hudson clays, which border the Gulf coast in Hancock, Harrison, and Jackson 
counties, is occupied by the Grand Gulf group. 
The thickness of this group is not definitely known, but from some deep-well records along 
the coast the drill is supposed to have penetrated the Grand Gulf at 750 to 800 feet. At 
this depth some fossils were found, which L. C. Johnson refers to the underlying Pascagoula 
marls. 
Lincoln, Copiah, Hinds, Simpson, and Rankin counties, and the counties along Mississippi 
River from Fort Adams to Vicksburg, contain the only outcrops of the sandstone, which in 
these localities alternates with white to bluish plastic clays. 
The following section from the type locality, Grand Gulf, is taken from Hilgard's Geology 
and Agriculture of Mississippi, page 148: 
Section of the bluff at Grand Gulf. 
Feet. 
12. Calcareous silt of the Bluff formation, forming the hilltops 60-70 
11. Grand Gulf sandstone, in ledges 10 inches to 2 feet in thickness; stratification often discordant 
and curved 14 
10. Gray sandy material, sometimes soft sandstone, with an argillaceous cement, alternating with 
harder ledges, 6 to 10 inches thick, of friable, whitish sandstone 15 
9. Solid whitish sandstone of good quality 2\ 
8. Greenish-gray clay, with white veins of carbonate of lime 2J 
7. Soft white sandstone 1 
6. Grayish-yellow pipeclay , £ 
5. Dark-gray, brittle sandstone 1 
4. Gray, semiindurated clayey sand 3 
3. Gray and yellowish sands and clays, semiindurated, interstratified 17 
2. Semiindurated gray sand 3 
1. Greenish-gray clay, with veins of carbonate of lime 2 
Doctor Hilgard mentions numerous other outcrops of Grand Gulf in this region, including 
several localities near Rocky Spring where beds of lignite occur. Wailes found a bed of lig- 
nite 2 feet thick between two ledges of sandstone; also in sec. 11, T. 4 N.,R. 3 W., and at Par- 
tins Ferry, Hinds County. Alternating beds of clay and sandstone are reported by Hil- 
gard at Fayette, Jefferson County, also in Franklin, Copiah, Hinds, Rankin, and Simpson 
counties. 
The following section from a bluff on the south side of Richland Creek, in sec. 12, T. 4 N. 
R. 2 E., shows the character of the lower 100 feet of the Grand Gulf: 
Section of Grand Gvlfbeds in sec. 12, T. 4 N., R. 2 E. 
Feet 
4. Ledges of Grand Gulf sandstone, 12 to 15 feet thick, alternating with gray clays on side of hill. (?) 50 
3. Dark-blue plastic clays, containing more or less sand and becoming lighter colored near bottom 
of hill G0-70 
2. Ferruginous sandstone containing greensand 
1. Calcareous greensand marl, with badly preserved fossils, extending to bed of creek 5 
The ledge of ferruginous sandstone marks the division between the Grand Gulf and thi 
underlying Vicksburg. Similar outcrops showing the lower clayey portion of the Granc 
Gulf overlying the Vicksburg formation were seen 1 mile south of Pearson, Hinds Count) 7 . 
A section of the Grand Gulf at Star, Rankin County, is very similar to that at Grand Gulf 
The sandstone comes to the surface in the hills at and near Star. In the railroad cut 100 
yards south of the station there are 5 feet of soft rotten sandstone with harder layers froi 
3 to 6 inches thick through it. This is overlain by about 10 feet of gray to white plastic clay 
containing some sand. The following section was obtained in the hills to the southwest, 
where the material is at a higher elevation than the outcrop along the railroad: 
