Tertiary Stratigraphy and Paleontology, Chesapeake Bay Region, Virginia and Maryland – July 15–July 17 Volume T216

Published by the American Geophysical Union as part of the Field Trip Guidebooks Series, Volume 216.

Stratigraphic units exposed in the Chesapeake Bay area consist of a succession of Mesozoic and Cenozoic Coastal Plain beds deposited in a tectonic downwarp known as the Salisbury embayment. As shown in figure 1, the Salisbury embayment covers parts of Virginia, Maryland, Delaware, and southern New Jersey and is bordered on the north and south by the South New Jersey arch and the Norfolk arch, respectively. Subsurface data shows that these arches are characterized by stratigraphic thinning or truncation of Cretaceous and Tertiary formations. Conclusive evidence of basement highs associated with the arches is lacking, however; this is strongly suggested by the evidence at hand, at least for the Norfolk arch. The basement complex underlying the embayment includes Precambrian and Paleozoic crystalline rocks and Mesozoic rift-basin fill. Reactivation of Paleozoic ramps and thrusts is believed to have influenced or controlled the distribution, geometry, and style of faulting associated with early Mesozoic rift-basins and overlying late Mesozoic and Cenozoic Coastal Plain deposits. The Salisbury embayment was the site of intermittent marine overlap and deposition during the Early and Late Cretaceous and most of the Tertiary. Beds are of fluvial, deltaic, and open-shelf origin and were deposited in a wedge-like configuration with their thin, westward edge overlapping the Appalachian Piedmont. To the east the Coastal Plain deposits thicken to several thousand feet.