And the “ Great Carolina Marl Bed.” 21 
oyster shells, which are of two very well defined and 
remarkable species: the long and the globular. The 
long species are sometimes found twenty-three inches 
in length, only two and a half inches wide, and about 
three inches thick at the hinge. They resemble in 
outline the ‘‘ Racoon Oyster” of the Southern coast, 
now living in its bays and harbors. The other species 
weigh five or six pounds, (each shell.) They are 
generally “as wide as they are long, and as thick as 
they are broad.” In a word, they are globular and 
very ponderous. 
This remarkable shell bed extends from the Santee 
to the Savannah Rivers; the strike of the outcrop of 
the bed is parallel with the coast line. 
THE BUHRSTONE OR SILICIFIED-SHELL 
FORMATION OF THE EOCENE AGE. 
Referring again to Plate I, the reader will see in the 
left-hand corner of the lowest division of the diagram, 
the name of a formation called “ Buhrstone,” which 
is the exposed, upturned, elevated edge or out- 
crop of the Santee Beds. It is clearly exposed on 
the farm of Mr. Caraduc, near Aiken. This ‘“ Buhr- 
stone” is a “living witness” of the remarkable and 
diverse changes which the same “rock” undergoes 
_ when subjected to the effects of different geological 
agents, as exhibited in itself and in the Phosphate 
rocks; both originally of the same geological forma- 
tion, viz., the Eocene. 
