40 GEOLOGY AND MINERAL RESOURCES OF MISSISSIPPI. 
shape by hand. It is then left in the open air, where it soon becomes hard. It is in 
most places free from fossils and when dry is almost pure white. 
At Vossburg the hard blue ledges of the lower Vicksburg occur in the hills one-half mile 
northwest of the town. To the northeast the low prairie land of the Jackson continues to 
near Pachuta. 
On the Ohickasawhay [says Ililgard a], between Red Bluff and the latitude of Waynesboro : both marls 
and limestones crop out with frequency; the same is the case on the creeks on the east side, as on Cak- 
cheys Mill Creek and Limestone Creek, especially near the mouth of the latter, at the foot of the hill on 
which l>r. E. A. Miller lives, the mosl southerly outcrop of the calcareous Eocenef now called Oligo- 
cenej on the Chickasawhay. 
PASCAGOULA FORMATION. 
Along Chattahoochee River in Florida a series of Oligocene beds overlain by a successioi 
of strata containing Miocene fauna lias been described by D. W. Langdon as Miocene. Oi 
paleontologic and stratigraphic evidence the upper Oligocene beds have been shown bj 
Dall & and Stanley Blown to rest directly upon the lower Oligocene or Vicksburg limestone 
The same Oligocene beds have been found by Dr. E. A. Smith on Conecuh River, neai 
Roberts, Ala. Deep borings at Mobile, Ala., have shown the Oligocene beds at a depth o 
1 ,550 feet below thr surface. 
Nowhere in Mississippi have the Miocene beds so far been discovered. However, on tht 
banks of Chickasawhay River, a few miles above the mouth of Leaf River, L. C. Johnson has 
found a. Tertiary bed of marl containing large oysters (Mactra lateralis Say), numerous smal 
Gnathodon Johnson!, and other forms. These fossils were referred to Dr. W. H. Dall, who 
doubtfully correlated the bed with the aluminous day horizon of the Alum Blulf section 
which is placed in the Miocene. 
The exact age of the bed has not been determined, but Mr. Johnson has given it the name 
Pascagoula and refers it to the Miocene. 
Dr. E. A. Smith, who visited the locality later, in speaking of the fossiliferous bed, said 
It, at the type locality, i covered by the sands, with silicified tree trunks and lignitizedwood belong 
ing to wha i Hilga rd called < 1 rand (Julf, but the material in which the shells are found may be the earn 
blue day assigned t<> the < I rand I iulf. lower bed, and occurring along the bank of Chickasawhay Rive 
from Bucatunna down to its confluence with Leaf River. Whether, therefore, this Pascagoula be( 
belongs to the Grand Gulf or not, it is below a great mass of material that has never been questionec 
as being < Srand Gulf. At Motile this same shell bed is penel rated to a depth of 700 feet, or thereabouts 
and several hundred feet above the Chattahoochee Miocene (now called Oligocene], which is reached a 
1,550 feet. In Mobile County, as in Mississippi, this shell bed is below a great mass of sands and clay 
that have been considered Grand Gulf. 
So, as a matter of fact, there come in between the Vicksburg and Lafayette, both in Alabama anc 
Mississippi, a greal -erics of marine Tertiary strata. -if M iocene age, at least in the lower beds, and thes 
marine Miocene beds and the Pascagoula (whatever its age may be) Lie below much, if not all, of what 1 1 il- 
gard designated as Grand Gulf, and what 1 take it is actually Grand Gulf. As before mentioned, noth- 
ing is known to overlie the G rand dull' beds older than the Lafayette, while the Grand Gulf is certainly 
known to overlie at least the Miocene, and, as many of us think, any other later Tertiaries if they exist 
along the Gulf border. 
Owing to the limited area of outcrop the formation is not shown on the map. 
GRAND GULF GROUP. 
The Grand Gulf group, as the term is here used and mapped, is possibly not a homo- 
geneous series of beds, but may include formations of differe.n1 age. It is certain, however, 
thai everything here included in the Graml Gulf is younger than the Vicksburg limestone 
and older than the Lafayette or ''Orange sand" formation. 
At the type locality of the Pascagoula formation, as well as at Mobile and other points, 
the Pascagoula beds are overlain by Grand Gulf beds; but further held work will be required 
before the relation of these two series in other areas can be stated with certainly. Such 
oGeblogyand Agriculture of Mississippi, i860, 146. 
b Kighteenth Ann. Rept. U. S. Geol. Survey, pt. 2, L898, pp. 327-348. 
