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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 Clai borne, Ala- 

 bama, where its fossils are in the greatest abundance and best 

 state of preservation. It is also very interesting 4n this locality, 

 from the circumstance of its resting on very white friable Se- 

 condary limestone, full of Xummulites, and containing Ory- 

 phcea, &c. which again reposes on the Green Sand. 



LOWER TERTIARY FORMATION. 

 Plastic Clay, of Englith authors ; Argilc plastique, Hrong. 



Miner alogical 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 

 Gay head, 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 referrible 

 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 formation has been detected in the superimposed strata. 



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