132: GEOLOGICAL SURVEY 
CHAPTER VI. 
Upper Secondary, or Cretaceous, System.— Tertiary Series—Eocene.—Buhrstone Formation.— 
Calcareous Beds of the Charleston Basin.— On the Santee-—On Cooper River.—On Ashley.— 
On Edisto.—On the Savannah.— Recapitulation. 
With the exception of a few unimportant beds, that occur on Thompson’s Creek, in Chesterfield, 
which Lhave referred, with doubt, tothe lower Silurian rocks, and a limited pateh of New Red sand- 
stone which is found on Clay Creek, in the same District, there is a wide gap in the geological 
series of South Carolina, extending from the metamorphic rocks to the Upper Secondary, or Creta- 
ceous, formation. Unfortunately, among the missing rocks, we find the Carboniferous system, with 
its coal measures. 
Whether the latter ever existed in the State, or not, it 1s now not easy to determine, but it is 
quite certain that nota vestige of the carboniferous rocks is to be found at present. There is 
nothing absolutely impossible in the supposition that these rocks may be covered and hidden from 
view by the Cretaceous and Tertiary beds; nevertheless it is exceedingly improbable: for along the 
Atlantic coast, between this State aud New Jersey, these beds are frequently removed by denuda- 
tion, and are found to rest, almost invariably, on the granite or metamorphic rocks, which is pre- 
cisely the position they occupy in South Carolina; nor has there been a trace of the carboniferous 
rocks found in this connection throughout the entire distance. 
The newer formations, particularly the Tertiary, are finely developed in the State; and to these 
attention will uow be directed. 
CRETACEOUS FORMATION. 
The Cretaceous formation of the United States, although deriving its name from the chalk found 
in contemporaneous formations in Europe, does not any where contain beds of true chalk, but is 
composed of beds of clay, quartzose sand, calcareous matter, or marl, and green sand, variously 
interstratified. 
The most interesting of these is the green sand, which, in New Jersey, where it has been long 
used as a manure, is called marl. It is composed of grains that are, sometimes at least, concre- 
tionary, and in size generally resembling ordinary gunpowder—the color green, inclining to black. 
It may be crushed by the finger-nail, and leaves a bright green streak, which is a simple and relia- 
ble test for this substance. 
Its distribution in our rocks is very remarkable. In New Jersey and Delaware, where it occurs 
extensively, it is characteristic of the Cretaceous formation. In Maryland and Virginia this forma- 
tion has not yet been recognised, and the green sand is found in the Tertiary, extending, in the 
