Environmental history of Maryland Miocene
1971, Gernant, R.E., Gibson, T.G., and Whitmore, F.C.
The Miocene is one of the most widespread stratigraphic units in the Atlantic Coastal Plain. It crops out almost continuously from southern Florida northward to Cape Cod, and is found offshore to the east of Cape Cod on Georges Bank (Gibson, 1965). Because the overlying deposits are thin, outcrops of the Miocene are relatively common throughout much of the Coastal Plain.
Although most Cenozoic strata presently appear because of erosion as a general offlap series to the east, some Miocene formations form large overlaps over Oligocene, Eocene, Paleocene, and Lower and Upper Cretaceous rocks. In some places in the central Coastal Plain, Mioeene beds lie unconformably on metamorphic and igneous rocks of the Piedmont Province. In the northern part of the Coastal Plain, the middle Miocene, represented in part by the Calvert and Kirkwood Formations, forms one of the largest regional transgressions in the Cenozoic; in the southern part, the Yorktown and Duplin Formations of late Miocene age form a significant transgressive unit.
In the field trip area, Miocene strata transgress Eocene, Paleocene, and Cretaceous strata, and rest as outliers on crystalline rocks of the Piedmont near Washington (Darton, 1951).