TERTIARY FORMATIONS, 237

says: “It was described by Emmons from the Miocene of North Car-
olina, but was not found by Burns in the Duplin beds;” referring to
Terebra dislocata var. indenta Conrad. “Habitat.—Duplin beds at the
Natural Well, Duplin County, North Carolina.” This is the ftrst use of
the name Duplin beds, but they were not there specifically defined.
However, in the Eighteenth Annual Report of the U. 8. Geological Sur-
vey, Part II, 1898, in Dall’s article, “A Table of the North American
Tertiary Horizons, Correlated With One Another and With Those of
Europe, With Annotations,” pages 327-348, the formation is definitely
named. On page 338 Dall states, “Duplin beds.—Late Miocene marls of
Duplin County, North Carolina,” and gives a reference to Conrad,
American Journal of Science, 1st ser., vol. 12, pp- 335-343. In the
Correlation Table “Duplin beds” occurs in the column headed Atlantic
States. Dall, in his Tertiary Fauna of Florida, Wagner Free Institute
of Science, vol. 3, part VI, 1903, pp. 1598-1603, gives a further account
of the Duplin beds and a detailed list of the fauna obtained from the
exposure in the Natural Well southwest of Magnolia. This formation
has frequently been considered in the literature, and probably no Ter-
tiary horizon is palecntologically more thoroughly known.

Definition—The formation consists of unconsolidated sands, arena-
ceous clays, and shell marls representing the latest phase of Miocene
deposition in the region south of the Neuse River. North of the Neuse
River the Yorktown formation occupies the same stratigraphic posi-
tion that the Duplin strata do in the southern part of the State, and
the two formations may be in part contemporaneous. The differences
in the faunas, however, render it inadvisable to include them in a
single formation.

In the regions where the Duplin strata occur no other deposits of
Miocene age have thus far been recognized, and wherever the basal
beds are exposed the formation is seen to rest unconformably upon
Cretaceous or Eocene strata.

In the vicinity of Mount Olive the Duplin formation rests upon the
Trent, with which it is markedly unconformable. In the vicinity of
Wilmington the Duplin beds are found immediately overlying the
Castle Hayne deposits. At present the Miocene strata are not known
to outcrop in Wilmington, but a few years ago, in excavating for the
foundations of the Y. M. ©. A. building, a deposit of Miocene marl
was found overlying the Eocene limestone of the Castle Hayne for-
mation. At the City Rock Quarries on Smith Creek Miocene marl of
the Duplin formation is found in several places occupying depressions
in the pitted surface of the Castle Hayne limestone. These pockets