TERTIARY EROSION INTERVALS NORTH CAROLINA AND VIRGINIA 677 



river, in Duplin county, and southward. It is best known in Duplin county, 

 North Carolina, where it is so well developed in the natural well near Mag- 

 nolia. It is unknown in Virginia or in northern North Carolina, but has been 

 recognized in several places in South Carolina. No doubt it is of the same age 

 as some of the beds in the vicinity of Darlington and on the Peedee river in 

 South Carolina. The Duplin formation, disappearing northward near the line 

 where the Yorktown appears, might suggest their equivalency were it not for 

 the fact that the Duplin strata contains a much more recent fauna. 



Pliocene Formation. 



Marine Pliocene deposits are unknown in Maryland and Virginia, though 

 certain beds in the vicinity of the Dismal swamp in Virginia have been 

 referred to this period. The evidence gained during the last year, however, 

 seems to prove conclusively that the beds referred to the Pliocene in that sec- 

 tion are in reality Pleistocene. Marine Pliocene beds, however, do appear in 

 the southern portion of North Carolina. They are well developed along the 

 Cape Fear river at Neills Eddy landing and Walkers bluff and in the vicinity 

 of Croatan, south of the Neuse river. Also along the Waccamaw river, in 

 South Carolina, the Pliocene is well developed, overlying the Peedee formation 

 of the Cretaceous. The Cape Fear River deposits have been referred to the 

 Waccamaw formation, and the fossiliferous strata near Croatan to the Croatan 

 formation. It is not improbable that the latter deposits may eventually be 

 referred to the Pleistocene, though they contain certain fossils that have 

 usually been regarded as distinctly Pliocene types. At Neills Eddy landing 

 and Walkers bluff the Pliocene is found in contact with the Cretaceous. Fos- 

 sils of Peedee age are contained in the strata immediately underlying the 

 Pliocene beds at the latter place. 



Summing up the evidence, we find that each one of the Tertiary formations 

 in North Carolina is separated both from the underlying and the overlying 

 formations by an erosional unconformity, and each formation is found in one 

 place or another in immediate contact with the Cretaceous. In Virginia the 

 unconformities are less noticeable. 



Relations of the North Carolina Tertiary Formations 



One of the most striking things brought out in the recent work is the pres- 

 ence of the sharp line of demarcation occurring in the vicinity of the Neuse 

 river. We seem to have evidence in almost every period of uplift during the 

 Tertiary of different conditions prevailing south of the Neuse river than to the 

 northward. Each of the Tertiary formations is almost entirely confined to 

 one side of the river. The evidence obtained in the recent investigations in 

 North Carolina seems to indicate that in that state we have a sharp change 

 both in the character of the fossils and in the lithology between the Coastal 

 Plain region to the northward and that lying to the south. The northern part 

 of North Carolina in almost every particular, so far as the Tertiary deposits 

 are concerned, seems to properly belong to the region lying to the northward — 

 Virginia and Maryland — while southern North Carolina, south of the Neuse 

 river, forms an essential part of the southern Atlantic Coastal plain, extending 

 southward to Florida and bordering the gulf of Mexico. Beside the evidence 



