Abstract:
Miocene, Pliocene, and Pleistocene strata were
deposited in two embayments in the central Atlantic Coastal Plain, the Salisbury to the north
and Albermarle to the south. Both embayments
underwent local tectonics, and no single area
within either has a continuous section.
Deposition in both embayments began in early
Miocene time. In the Salisbury embayment, the
early deposits were largely biogenic (Fairhaven
Member of the Calvert Formation), and the center of deposition was located in Maryland. Relatively continuous clastic deposition commenced
in the late early Miocene and continued through
the middle Miocene (Plum Point Marl Member
of the Calvert Formation and the Choptank and
St. Marys formations). Deltaic deposition began
in the northern part of the embayment, as seen
in the Calvert and Kirkwood formations and
influenced environments west of the delta lobe.
The center of deposition in the Salisbury embayment shifted southward into Virginia during late
Miocene time (“Virginia St. Marys” beds) and
continued there through the early and middle(?)
Pliocene (Yorktown Formation); only the southeastern part of the embayment received sediments
in the late Pliocene and early Pleistocene (upper¬
most part of the “Yorktown” Formation). Environments throughout this time were largely inner
shelf (less than 60-m depths), and some marginal-
marine to nonmarine intervals.
The Albemarle embayment in North Carolina
received largely biogenic and biochemical deposition during the early and early middle Miocene
(Pungo River Formation). This was followed by
uplift in the late middle and late Miocene. Clastic
sedimentation started near the Miocene-Pliocene
boundary and continued with minor hiatuses
throughout much of the Pliocene and into early
Pleistocene (Yorktown, uppermost part of the
“Yorktown,” Duplin, Croatan, and Waccamaw
formations). Some Pungo River strata formed in
middle-shelf environments as deep as 100 m; most
younger strata were deposited in inner-shelf environments (less than 60-m depth), but some in
marginal-marine intervals.
