34 GEOLOGY AND MINERAL RESOURCES OF MISSISSIPPI. 
fossils and stratigraphy from the upper Claiborne to the lower Jackson. Many of the forms 
found in the Claiborne are found throughout the Jackson and the succeeding formation, the 
Vicksburg. 
Conrad a described a large number of fossils from the vicinity of Jackson, and was the 
first one to give that name to the formation. 
He assigned [saysDall *>] to the strata their proper stratigraphical position above the Claiborne and 
below the Vicksburg, although from the nature of the material he had for examination he failed to recog- 
nize the true faunal relationship of the several horizons. His investigations led him to the conclusion 
that there were no forms in common with the Vicksburg series, and but four or five with the Claiborne. 
Subsequent observations, however, have shown in Mississippi, as well as in Alabama, that there are 
many forms common to the three horizons. Such common species as Cardita planieosta and Cardita 
rotunda of the Claiborne, with many less usual types, are found, while the list of species reported as like- 
wise occurring in the Vicksburg is very large. 
There is one distinguishing fossil, the Basilosaurus (Zeuglodori) , which has been found only 
in the Jackson marls. It is usually found on the prairies where the streams have removed 
the surface soils. These bold prairies, somewhat similar to those found in northeastern 
Mississippi, are of common occurrence over the Jackson area and serve to distinguish the 
Jackson from the Claiborne. 
Hilgard,c in his study of the formation around Jackson, observed what he considered a 
northern dip of the Jackson beds. He says: 
According to the levelings of the N. O., J. and G. N. R. R., the city of Jackson is situated 45 feet higher 
than Canton, Madison County, <* which is distant 25 miles due north from the former place. ... At 
Canton we find the highest strata, apparently, of the Jackson group— the gray calcareous clay matrix 
of the Zew^Zodon— occupying the surface, though at a moderate depth (20 to 30 feet) the lignito-gypseous 
material is struck, yielding undrinkable water. The same strata are seen all the way between Canton 
and Jackson, and crop out very characteristically half a mile north of the statehouse. Yet we find 
lignitic strata cropping out on Moodys Branch, a mile northeast of the statehouse, and that at a 
hypsometrical level obviously higher than that at which, a mile below, we find the beds of blue fossil- 
iferous sand cropping out on Pearl River and in the bed of Dry Creek. Making due allowance for the 
undulations of the surface at both stations (Canton and Jackson), the surface of the lignitic strata, so 
far from exhibiting a southward dip, is still slightly higher at Jackson than at Canton. It seems dif- 
ficult to account for this condition of things unless by supposing a local upheaval of the underlying 
formation to have taken place before the deposition of the lowest of the Jackson stage. 
Doctor Hilgard's theory of a northern dip of the strata in the vicinity of Jackson is further 
substantiated by the occurrence of outliers of the Vicksburg limestone west of Madison. 
These outliers occur on the hills along the watersheds of Pearl and Big Black rivers, but 
if the southern dip of the Vicksburg, as observed along Pearl River at Byram, continued 
northward the Vicksburg would not touch the tops of even the highest hills, as the following 
elevations will show. The elevation of the lowest member of the Vicksburg limestone on 
Pearl River, 3 miles above Byram, is about 255 feet above tide. Byram, on the bank of 
Pearl River, is 264 feet above tide. The United States Geological Survey bench mark in 
sec. .'i T. 7 N., R. 1 E., is 415 feet above tide. This is 1 mile from the northernmost outcrop 
of the Vicksburg outlier in sec. 10, T. 7 N., R. 1 E., west of Madison, where the elevation of 
the lowest member is 400 feet above tide, barometric reading. The distance between the 
northernmost outlier. and the outcrop on Pearl River above Byram is 20 miles and the differ- 
ence in elevation is 145 feet. The southward dip would, therefore,be 1\ feet to the mile. 
The dip thus obtained is much smaller than that noticed along Pearl River between Jack- 
son and Byram. D . W. Langdon,e who studied the strata along this part of the river, says: 
Six miles above Byram the strata show a dip of about 20 feet in a hundred toward the south. . . . 
Still farther south the strata dip southward very rapidly, as much as 5 feet in a hundred. 
a Proc. Philadelphia Acad. Nat. Sci., vol. 7, 1855, pp. 257-263. 
b Correlation papers— Eocene: Bull. U. S. Geol. Survey No. 83, 1891, p. 68. 
c Geology and Agriculture of Mississippi, 1860, p. 128. 
<t Aeeording to Gannett, Jackson is 67 feet higher than Canton. 
e Am. Jour. Sci., 3d ser., vol. 31, pp. 202-209. 
