Published by the American Geophysical Union as part of the Field Trip Guidebooks Series, Volume 217. The Maryland-Delaware coast (Figure 1) is located on the Delmarva Peninsula, part of the Atlantic Coastal Plain of eastern North America. The emerged portion of the Coastal Plain province is formed of Cretaceous and Tertiary clastic sediments, overlain by a thin veneer of Quaternary deposits. Holocene coastal environments in this area include barrier islands, coastal sand dunes, overwash flats, coastal bays (lagoons), fringing and backbarrier marshes (wetlands), tidal inlets, headland beaches, prograding spits, and intertidal flats. Pre-Holocene examples of similar coastal deposits are also represented in inland areas.