ee » .d . 
OF SOUTH CAROLINA. 239 
From Gillett’s mill, Gen. Erwin’s, firmer parts..-..--------------- 64 
s do. softest part, (grannlanjeseea= 2 --ao-— sees 46 
“* Rey. Elliott Estes’s land, on Savannah River, (above Lower Three 
1 yt) is ee a eee 92 
£6 do. marlstOn0)s eee se snee ecto aces 90 
« Major J. G. Brown's, Lower Three Runs, upper part---------- 504 
ge do. 10 feet below surface. 32 
Of Little Salkehatchie and its branches. 
romeDowlitie’s Mill Sos aoe eS. Se eee ce 7 
Cedar spring, on Lemon Swamp, (Miller's land).---..-....--- 73 
On Ashepoarriver, frome. Wraser’s' 25-2. 2-2-0 5 so eee oe 92 
The marls of the Pliocene, mineralogically considered, present two well marked varieties: the 
yellowish white marls, from which the shells have almost all disappeared, and the gray marls of 
Darlington, Sumter, and of the upper beds on the Waccamaw, where the shells are well preserved, 
and very numerous. In the yellow marls, composed of casts of shells, cemented together by lime, 
one is likely to be deceived in the amount of that mineral present in them, for a large part of what 
appears to be sand is composed of crystalized lime. This ig the case with the marl on Goose 
Creek, as well as with some of those on the Peedee and Waccamaw. Of the two varieties, the yel- 
low is richer in lime. But it is remarkable that an average of the whole shows a greater amount 
of lime than is found in the richest marl in Virginia. 
The newer geological formations of South Carolina are as distinctly marked by the amount of 
carbonate that they contain, as by their organic contents. The marls of the cretaceous beds have 
from 25 to 70 per cent. of lime. In general, the soft marls are poor, the larger amount of lime 
being mostly confined to the marl stones. During the deposition of the Santee beds, lime abounded. 
It was not all derived from the decomposition of shells, but resulted, in part, from the debris of 
corals, and from lime held in suspension in water, producing a white, caleareous mud, and hence 
the large amount of lime in some of the beds. The lime began to diminish during the period in 
which the Ashley beds were deposited —white, calcareous mud still predominating. The Pliocene 
deposits are remarkable for the uniformity of the quantity of lime they contain. 'This arises from 
the fact that the lime is derived immediately from the shells, and in but afew instances is there the 
appearance of any other source. 'The shells being all of the same species, and distributed in the 
Miocene sea in about the same proportion, the beds enclosing them present great uniformity. 
Some of thé Pliocene marls which I examined are composed as follows. 
Marl from Tilly's Lake, Waccamaw. 
Cirbonate of limesas 25 eel ee gs Sue Se vn coe 65.0 
SiliGars cae ee Se ee ee a eee me ese ek 20.0 
Alaminpandiirone= = oho). See ee aes eb! |e 15.0 
100.0 
From Mr. McBride's, Black River, Sumter. 
Canhonstem ines 2223... canoe ean ee eee 70.0 
SILC R ea a oc 2 = a eae iat oo eee 200 
*This was a part detached from the Uy surface, in excavating for the mill site, and was not worth notice, except as indicating 
that marl may be found, probably much better, lower in the bed. © 
