. eal & 
OF SOUTH CAROLINA. 139 
Pectunculus hamula Mor. 
Anomia argentaria e 
Cuculleea ovata. 
Trigonia thoracica, Mort. 
M: crenulata. 
Cardium altum. 
“ sp 2 
Crassatella vadosa, Mor. 
Hamulus onyx, ff 
Tertiary SERIES. 
Pursuing our investigations upwards, we next come to a group of rocks, presenting altogether a 
different aspect from those we have just examined. The dark beds of marl and marl stone of the 
latter are replaced by thick strata of white limestone, and beds of highly calcareous marl, that 
remind one of chalk. So totally unlike in mineral composition, are the Cretaceous and Tertiary 
rocks of South Carolina, that even in the absence of organic remains, they cannot, in general, be 
confounded with each other for an instant. 
I stated, in another place, that green sand was a prominent constituent of the Lower 'Tertiary of 
Maryland and Virginia. In the green sand strata of the latter State there is frequently not a trace 
of lime, and when it is present it rarely exceeds 25 to 30 per cent. ‘These are, however, interstra- 
tified with caleareous beds; but even in these the lime seldom amounts to 60 per cent. 
It is not before we reach North Carolina that we find beds at all approaching in mineral char- 
acter those of South Carolina. Above Rocky Point, on Dr. McRee’s plantation, white limestone 
and marl oceur, abunding in corals, and in all respects similar to the Eutaw beds, in this State. 
Marl Bluff, about thirteen miles from Wilmington, on N. E. Cape Fear, is another locality where 
a white caleareous bed is found, made up of the comminuted shells of Echinoderms. 'These and 
the beds at Wilmington are good examples of the great calcareous deposits of the Tertiary of 
South Carolina, 
We have, in the accumulations going on along our coast, at the present time, analogies that ena- 
ble us to understand the cause of the difference in the amount of calcareous matter in contempo- 
raneous beds, at distant localities. 'There is not more difference in this respect, between the Virginia 
and South Carolina strata, than there is between the deposits forming at this moment on the coast of 
Virginia and on that of Florida. I saw, in the cabinet of Prof. Gibbes, of Charleston, specimens of 
calearereous mud, brought from Key West, by Dr. Wurdeman, which so closely resembled the Cooper 
River marls, that it was difficult to distinguish the two. This mud is accumulated in great quan- 
tities in the vicinity of coral reefs, and is from thence distributed along the shore. The shells of 
molluses are buried in it, in vast numbers, and in time it may present the counterpart of our rich 
shell marl. Farther north the coast deposits consist of mud, sand, and comminuted shells, which 
also serve as the burying ground of numerous molluscs, that leave behind their well preserved exu- 
vie, and present us with types of a former state of things. 
The physical changes that could have so completely affected the mineral contents of two 
