OF SOUTH CAROLINA. 41 
earth. The oldest of these formations pass, by insensible gradations, into the metamorphic rocks, 
from which they can only be distinguished, as I have already remarked, by the presence of fossil 
remains. In mineral character they are generally less chrystalline, and the comparative abundance 
of carbonate of lime also serves, in some measure, to distinguish them from the metamorphic rocks. 
As we ascend in the scale the lime increases, the strata become less consolidated, until we reach 
the beds of loose sand, clay, &c. that characterise the deposits now in process of formation. 
The earliest classification of these rocks consisted of a division into three great groups or 
systems, designated the Transition, Secondary, and Tertiary Systems. The Transition rocks 
included those that were deposited during that period in which the earth was supposed to be in a 
state of passage from an uninhabitable to a habitable state, and these rocks consequently contain 
the remains of the earliest inhabitants of the globe. 
The rocks of the Secondary period give evidence of a second great change in the physical con- 
dition of our planet, which affected, in a remarkable degree, the character of its Fauna and Flora. 
And the fossils entombed in the rocks of the Tertiary present a nearer approach to the living 
forms of the present period. 
More extended investigations have shown each of these great divisions to contain many groups 
quite distinct and well characterised. 'The distinctive characters of these groups are derived from 
the combined evidence of superposition, mineral contents, and organic remains, but principally from 
the latter. 
TABLE, 
Showing the order of superposition of the Fossiliferous Rocks. 
RECENT PERIOD, OR POST PLIOCENE. ; 
Systems, Formations, and | Localities of characteristic | European Equivalents and } 
Groups. deposits in America. Localities. ; 
Alluvium, Superficial deposits. | Found in all countries.’ 
Stratified beds of clay\ Northern States. ; 
‘and sand,containing the| Atlantic coast. 3 
‘remainsof extinct mam- ; 
‘mals and recent shells. 
Drift, or Diluvium. Northern Kurope. — } 
$ 
} 
TERTIARY PERIOD. 
Newer Tertiary, or South Carolina. Till of the Clyde valley, 
Pliocene. Norwich crag. 
Subapennine beds. 
Middle Tertiary, or Maryland, Red crag, } 
Miocene. Virginia, Basin of the Rhine, 
3 North Carolina. Molasse of Switzer- 
3 land. 
: Older Tertiary, or Maryland, London clay, 
Eocene. Virginia, Paris Basin, } 
; South Carolina, Auvergne. 
Alabama. 
11 
