748 



INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



Clark,"" Miller,^^" and Gardner. To Miller we are indebted for the detailed stratigraphy and 

 to Gardner for an exact knowledge of the moUuscan faunas. 



The scheme of classification adopted for the North Carolina Tertiary deposits is as follows: 



Pliocene (?) Lafayette formation. 



Pliocene Waccamaw formation. 



Miocene Chesapeake group: 



Yorktown formation north of Hatteras axis; Duplin formation 

 south of Hatteras axis. 

 St. Marys sand (north of Hatteras axis). 



Eocene I Castle Hayne limestone ]^^ ^^ ^^^^^^^ ^^^_ 



[ Trent marl J 



The Trent, which overlies the Cretaceous deposits unconformably, consists of calcareous 

 marls and clays, the former locally indurated, forming a compact limestone. The deposits 

 have a thickness of about 50 feet. The fauna consists chiefly of marine invertebrates. The 

 formation covers a small area in the valley of Trent River. 



The Castle Hayne consists chiefly of calcareous marls and sandy clays. It has a thickness 

 of about 50 feet and contains a fauna of late Eocene age. It apparently overlies the Trent 

 unconformably. 



The St. Marys and Yorktown formations in North Carolina are in general similar in character 

 to the same deposits in Virginia. They are both confined to the area north of the Hatteras 

 axis. 



The Duplin formation consists of sands, clays, and marls and represents the Yorktown 

 formation south of the Hatteras axis. It has a thicloiess of 100 feet and contains an extensive 

 marine fauna similar to the Yorktown but of a warmer-water facies. 



The Waccamaw formation consists of sands, clays, and marls. It is confined to a narrow 

 belt along the eastern margin of the State where it rests unconformably on older formations. 

 It has a thickness of about 50 feet. Its fauna is marine in character and consists of characteristic 

 Pliocene forms. 



The Lafayette formation consists of sands, loams, and gravels and is confined chiefly to 

 outliers west of the main body of Coastal Plain sediments, where it forms the series of "sand 

 hills." 



General remarks. — The Tertiary deposits of this region overlie the Cretaceous strata uncon- 

 formably, but owing to the differential movements already described the later transgress the 

 earlier formations in certain areas, so that the Cretaceous deposits are in some localities overlain 

 by Eocene and in others by Miocene or later formations. The dip of the Eocene formations 

 rarely exceeds 15 feet in the mile toward the east and is in many places less; the dip of the 

 Miocene formations is 10 to 12 feet in the mile, and that of the Pliocene formations is even less. 



The correlation of the Tertiary formations within the region and with other areas is shown 

 in the following tables. 



Eocene formations in northern fart of Atlantic Coastal Plain. 



