OF SOUTH CAROLINA. 147 
ern part of Orangeburg District. The distance below Columbia is about eighteen miles, and this 
is the highest point on the Congaree where any organic remains of the Eocene are found. 
Around Totness the silicified shells are found in a bed sufficiently hard to be used for building 
purposes, and about a mile farther south, at Butler’s mill, the clay stratum makes its appearance, 
on the side of a hill, about fifty feet above the level of the mill pond. It is underlaid by the mottled 
clays and sand, and above it is a band of iron ore. . 
The upper sandy stratum that covers the upper part of the District now thins out as we descend 
towards McCord’s Ferry, and the yellowish and red loamy beds of the Buhr-stone formation appear 
at the surface, and form a wide and well marked belt, that extends across the country. The peculiar 
ochrey color of the subsoil of this belt is so different from that of all the others of the State, that it 
enabled me to identify the formation to which it belongs, on the Peedee, before I had seen any fos- 
_sils or other evidence of its existence there. 
Crossing the Congaree and Wateree, near their confluence, I was not a. little surprised, on emer- 
ging from the low grounds of the latter river, to find the first rocks in view, on the brow of the hill, 
to be the silicified shells and associated bed of clay. I had now traced these beds from Barnwell 
to Sumter, a distance of one hundred miles, and it was curious to find them here retaining all their 
characteristic features and relative position. ‘The buhr-stone has fallen down from the hill, and 
large blocks are scattered on the road side: the fossils are so much broken and so firmly cemented, 
that I could not identify a single species. 'The bed of silicious clay is laid bare on the brow of the 
hill, for a considerable distance, and fragments from the outcropping edge strew the surface. Mr. 
Ruffin examined this stratum in several places, in Sumter, and was also struck with the uniformity 
of its appearance. It underlies the sand-hills of the District in heavy beds, and has received the 
name of “Fuller's earth.” Casts of fossils are found in it, but they are few and small, and I only 
made out among them Pecten Lyelli. Beyond this, towards the Hast, it is not again seen, although 
the associated bed of silicified shells is found on the Peedee. I first observed the sienna-colored 
loam and sand of the buhr-stone, about sixteen miles north of the mouth of Lynch’s Creek, and at 
Gordon’s old mill I found masses of that rock, containing Cardita planicosta, and Turritelli Mor- 
toni. Above Mar’s Bluff there are also silicified shells that I refer to this formation. 
Mr. Ruffin observed other beds of buhr-stone, on Black River, below King’s Tree, but states that 
the shells were very imperfect, and that they were, in some cases, still undergoing the process of 
petrifaction, for he found some of them having a part of the calcareous matter left. 
A similar phenomenon may be seen at Stroman’s, on Rocky Swamp, Orangeburg, where I found 
Cardita planicosta, with a portion of the shell composed of chalky carbonate of lime, and the rest 
silicious. What was most remarkable, was the apparent preservation of the ligament of the hinge. 
The smooth outer surface was complete, and when broken, it presented the fibrous structure pecu- 
liar to that part of shells. It was, however, carbonate of lime that had assumed that form. I had, 
on another occasion, seen,in Virginia, the large muscle of Ostrea compressirostra replaced by the 
same substance, which preserved the appearance and structure of the real muscle. 
That the removal. of the lime, not only of the shells, but of the marl, is constantly in progress, 
there are numerous examples throughout the marl region of the State. 
There are some beds from which every particle of lime has been removed, leaving a white, 
porous substance, that cannot, from external characters alone, be distinguished from the richest 
