TERTIARY FORMATIONS, 229

One and One-fourth Miles West of Walters, Wayne County.—Mio-
cene marl was dug at this place a few years ago. The fossil shells rep-

resent a large variety of species and are contained in a matrix of bluish-
gray argillaceous sand.

YORKTOWN FORMATION,

Name.—The Yorktown formation receives its name from Yorktown,
Virginia, where beds of this age are well developed and from whence
many excellent fossils have been obtained. The name “Yorktown” was
applied to all the Miocene and Pliocene strata of the Atlantic Coastal
Plain by James D. Dana in 1863, but not until 1906 was the formation
definitely described by Clark and Miller (Va. Geol. Surv. Bull., No, Hie &
pp. 19-20, Richmond, Va., 1906). The formation has not been repre-
sented as extending south of Virginia in any publications that have thus
far appeared, but in the collection of material for this chapter it has
been found that the formation with few changes does extend from
Virginia southward into the State of North Carolina.

The beds in North Carolina that are now referred to the Yorktown
formation have usually been considered a part of the undifferentiated
: Miocene, though the same strata were referred by Heilprin to the
EE “Carolinian division” of the Miocene.
oe Definition—The Yorktown formation comprises the latest Miocene

strata of northern North Carolina and, with the Duplin formation,

which is probably in part contemporaneous, constitute the uppermost

divisions of the Miocene of the Atlantic Coastal Plain. In Virginia

two Miocene formations are found beneath the St. Marys and the York-
_ town, but these have as yet not been recognized in North Carolina, and
it seems that they are entirely absent. The Yorktown rests directly
upon the St. Marys, with which it is unconformable.

This formation extends in discontinuous patches across the north-
eastern part of the State, being especially well represented along the
Chowan, Lower Roanoke, Lower Tar, and Lower Neuse rivers and
their tributaries. Other isolated patches of small areal extent are found
in intervening regions. :

_ As stated above, the Yorktown formation rests upon the St. Marys
Strata wherever these are developed, but in their absence it is found in
immediate contact with the underlying Eocene or Cretaceous. Along
_ Wiceacon Creek and the Chowan River it rests upon St. Marys strata,
and the same is true of the deposits found near Washington on the Tar
River. Along the Lower Neuso River in the vieinity of New Bern the
St. Marys formation is wanting, and there the Yorktown rests directly
upon the Trent formation. This is well exhibited at Rock Landing on