196 Tertiary. 



exhibits ciystalline limestones. It is bighly fossiliferous. Estimated 

 tliickness, including the lignite at its base, 112 feet. 



The Grand Gulf Group covers an immense extent of countr}' south 

 of the Vicksburg Group, and is composed essentially of clays and 

 sandstones, the latter generally rather aluminous and soft, and of 

 white-gray and yellowish-gra}' tints; the sand being very sharp. It 

 takes its name from the bluff at Grand Gulf on the Mississippi river, 

 where it is well exposed. It is overlaid near the coast by strata of 

 Pliocene and Post-pliocene age. Estimated thickness, 150 feet. 



Prof. F. S. Holmes* made three vertical sections of the Post-pliocene 

 strata of South Carolina in descending order as follows: 



1. The marine bed of the Wadmalur, consisting of yellow sand, 15 

 feet; ferruginous sand with casts of shells, 2 feet; red clay, 2 feet; and 

 gray sand and mud with comminuted shells and fossils in fine preser- 

 vation, 3|^ feet. 



2. The Ashley river beds, consisting of yellow sands with bands of 

 ferruginous clay, 4 feet, and blue mud resting on the white Eocene 

 marl, 1 foot. 



3. The Goose creek beds, consisting of yellow sand, 12 feet; blue 

 mud, 2 feet; ferruginous sand containing bones, 3 inches; yellow sand, 

 3 feet; and Pliocene marl resting on the Eocene white marl, 12 feet. 



The fossil bones obtained from these strata are often in a fine state 

 of preservation, especially those taken from the blue mud, which are 

 generally petrified; those from the sands are likewise well preserved, 

 but in the peaty or upper beds they are not so petrified, retain all their 

 gelatin and appear to decompose rapidly. They consist of the bones 

 of horses, hogs, dogs, rabbits, beavers, the tapir, and other mammalian 

 remains. 



T, A. Conradf described, from the Eocene of Alabama and Missis- 

 sippi, Exilia peryracilis, VoIutiUthes Umopsis, V. rugatus, Athleta 

 leioderma, Simpulum showwalteri, 8. autopsis, S. exilis, Galeodia tri- 

 carinata, Cithara nereidis, Murex morulus, PseudoUva tuhercuUfera, 

 Scala lintea, 8. octolineata, 8. staminea, Actoeonina suhvaricata, 

 Tornatella^a bella, Cerithioderma prima, Mazzalina pyrula, Leda 

 bella, now Nuculana bella, L. eborea, now N. eborea, Axincea belli- 

 sGulpta, Diplodonta astartiformis, D. deltoidea, Crenella latifrons; 

 from Texas, PseudoUva carinata, P. fusiformis, P. linosa, P. per- 

 spectiva, and Monoptygma crassiplica. 



* Proc. Acad. Nat. Sci., vol. ii., and iu Post-plioceue Foss. S. Carol'ua. 

 i Jour. Acad. Nat. Sci., 2d ser., vol. iv. 



