14 
pears to the north. We have seen fossils peculiar to it, said to 
be from Virginia, but the exact locality is unknown. It occurs 
again at Vance’s Ferry, South Carolina, and at Claiborne, Ala- 
bama, where its fossils are in the greatest abundance and best 
state of preservation. It is also very interesting in this locality, 
from the circumstance of its resting on very white friable Se- 
condary limestone, full of Nummulites , and containing Gry - 
phsea , & c. which again reposes on the Green Sand. 
LOWER TERTIARY FORMATION. 
Plastic Clay, of English authors ; Argile plastique, Brong. 
Mineralogical characters. These consist in alternating strat- 
ified beds of sand and gravel, of various colours; in these beds, 
and especially in the clay, Lignite is an abundant and charac- 
teristic substance. Iron pyrites and Succinite , Brong., also 
occur; the former in great abundance. Professor Hitchcock 
has lately discovered a silicious breccia in the Plastic clay at 
Gayhead, Martha’s Vineyard. 
In France, the black clay and Lignites form a superstratum 
of this formation ; the true Plastic clay deposit being abso- 
lutely composed of various coloured and seemingly pure clays, 
used in the potteries, and containing fresh water and marine 
shells. 
Organic characters. Besides the Lignite , a few casts of 
marine shells occur in our Lower Tertiary, apparently refen ible 
to the genera Venus , Tellina , &c Professor Hitchcock has 
also discovered in the quartzose breccia mentioned above, bones 
and teeth of the shark, crocodile, &c. 
Geographical distribution. We are indebted to Mr. John 
Finch for the first detailed account of this formation, in Ameri- 
ca, which appears to extend, in patches, from the islands of 
New England to the States bordering the Gulf of Mexico. Its 
most obvious localities are, Martha’s Vineyard; Sand’s Point, 
on Long Island ; Bordentown, Whitehill, & c. in New Jersey; 
Telegraph Hill, near Baltimore; Cape Sable, in Maryland, and 
many other places farther south. 
All the preceding formations are based on the Ferruginous 
Sand series , and Dr. Morton has shewn, that so far as his in- 
vestigations have extended, no species of fossil shell of the lat- 
ter ormation has been detected in the superimposed strata. 
