STRATIGRAPHY. 41

TERTIARY.

The Tertiary deposits consist of sands, clays, and marls, the last being
highly glauconitic at the lowest horizons and calcareous higher in the
series. They represent the Eocene, Oligocene, Miocene, and Pliocene
periods. Oligocene strata are apparently absent from the middle and
northern Coastal Plain regions, and therefore will not be further con-

sidered in this connection.
Eocene.

Deposits representing different horizons of the Eocene are found
seattered more or less irregularly either along the eastern margin of
the Creiaceous formations or as the result of transgression as iso-
lated outcrops on the surface of the Cretaceous or even beyond the
latter on the crystalline rocks of the Piedmont Plateau. The older
Eocene deposits, which are largely sands, are highly glauconitic, in
this respect showing a marked similarity to the Cretaceous beds be-
low. The later Eocene deposits lose their glauconitic character and
become often highly caleareous, the materials frequently being indurated
by the caleareous cement. A profuse infralittoral fauna, chiefly repre-
senting the mollusea, bryozoa, echinodermata, zoantharia and forami-
nifera with fish teeth and reptilian bones and coprolites, is found.

The Eocene deposits of North Carolina consist of the later facies of
Eocene sedimentation. They are highly calcareous and often indurated
and occur irregularly scattered over the surface of the Cretaceous for-
mations and even transgressing the latter onto the Piedmont Plateau.
They often occur in depressions in the Cretaceous surface where they
have withstood the erosion to which the rest of the deposits have been
subjected, since there is every reason to believe that the Eocene beds
had a much wider extent formerly and that the present isolated outcrops
are merely remnants of a continuous or nearly continuous sheet. The
Eocene deposits of North Carolina are all to the south of the Hatteras
axis, as far as known. They are divided into the Trent and Castle
Hayne formations, the relations of which are unknown from any ob-
served contact, except in a single well boring, but they are probably
unconformable, just as the Eocene deposits are unconformable every-
where in North Carolina to the underlying Cretaceous. Fossils of in-
_ fralittoral marine types are numerous, although the molluscan forms
are with difficulty determined because ie oceur largely as imperfect

oust. : :

‘Miocene.

Miooass deposits constitute a thick mantle over the eastern margin
of the older formations throughout much of the Coastal Plain area and