LONG-ISLAND DIVISION. 
277 
lopment is in the southern counties of Alabama and in Florida. There is a belt of prairie 
land passes through central Alabama, based on the lower division or greensand ; and where 
this terminates on the south, the upper cretaceous limestone commences, and is continued 
through Florida nearly to the Gulf of Mexico. 
“ Tertiary Formations. In some places, the greensand derived from the cretaceous strata 
enters largely into the composition of the lower tertiary marls. In Georgia, and more rarely 
in Alabama, a portion of the formation assumes the character of burrstone, and the shells 
which abound in it are beautifully silicified. Near Fort Washington, on the Potomac river, 
the lower tertiary is very similar in aspect to the Bognor rocks of Great Britain, and contains 
the Panopea {Mya) intermedia and Ostrea hellovicina of that locality. In this formation we 
meet with the first creation of testacea which have a near resemblance to recent shells; but 
yet in this country, all the species appear to be distinct from existing types. But two or 
three genera among the minute shells occur, which are unknown in a recent state. A very 
interesting section of the lower tertiary is presented at Claiborne, Alabama; where I col¬ 
lected about two hundred species of shells and corallines, many of which are identical with 
Eocene species of Europe. Among these are Cardita planicosta, Corbis lamellosa, Cytherea 
erycinoides, Bulimus terebellatus, Pyrula tricarinata. Solarium patulum, &c. 
“Medial Tertiary. An extensive formation of sand and clay, abounding in finely pre¬ 
served shells, follows the preceding strata in the ascending order, and contains only one 
species which is not widely different from the fossils of the latter formation. There are about 
one hundred and seventy species at present collected; and of these I have ascertained about 
twenty-three to be recent, nearly all of which inhabit the Atlantic coast and that of the Gulf 
of Mexico. Whatever the percentage of recent species may ultimately prove to be, I have 
no doubt the period of this formation was contemporaneous with that of the Older Pliocene 
strata of Europe; a belief founded on the great similarity of their respective groups of shells, 
and remote analogy of the American group to the Miocene of Europe, which, I have long 
believed, has no representative in North America, at least among the known tertiary deposits. 
The medial tertiary formation occurs along the Atlantic border from New-Jersey inclusive, 
to the Santee river in South Carolina. 
“ Upper Tertiary. This group of fossils is found in Maryland, Virginia and North-Carolina, 
in the same tract with the preceding, but is not so extensively distributed. Very few of the 
species of the medial tertiary occur, but the mass consists chiefly of recent shells, many of 
which inhabit the same parallels of latitude on the Atlantic coast of the Union, and the others 
chiefly the southern coast. There are, however, enough extinct species to bring the group 
within the limits of the Newer Pliocene.”* 
Of the influence of the northern current in giving an arctic character to the shells, the 
following observations of Mr. Conrad and Mr. Lyell may be adduced on the quaternary for¬ 
mations ; 
‘ Geological Report of New-York for 1841, pp. 44, 47. 
