A NEW STRATIGRAPHIC INTERPRETATION OF THE SURFACE SANDS OF THE LOWER DELMARVA PENINSULA, VIRGINIA USA

This study provides insights into the age, extent, and depositional history of the surface sequence of eolian sands that overlie a paleosol of previously undetermined age at Savage Neck, VA on the southern Delmarva Peninsula. References to this stratigraphic sequence in past literature and maps have suggested that these eolian sands were deposited during the rapidly changing deglacial period of the late Pleistocene. However, recent discovery of cultural artifacts from the paleosol raised questions regarding the past interpretations of this landscape. Using a combination of airborne LIDAR, stratigraphic, radiocarbon, and ground-penetrating radar data, the age and extent of the paleosol were investigated. Our results suggest the following: 1. The most recent airborne LIDAR data depict the study area as part of a 23 kilometer-long complex of dunes that lie atop the otherwise flat, older landscape, often extending several hundred meters inland to the east. 2. A GPR profile beginning at the Chesapeake Bay coastline and terminating 140-meters inland shows a buried surface consistent with the expectations of the lateral extent and depth of the paleosol beneath the overlying sands. 3. Cultural artifacts found within the paleosol and 10 related organic samples selected for radiocarbon dating provide a time constraint for the sequence that suggests the paleosol is approximately 1000 years old and the dunes were actively migrating within the last few hundred years. The sum of our data suggests that the eolian sands in the study area do not belong to the late Pleistocene, but instead were deposited during a period when this landscape was assumed to have been relatively stable. These results underscore the value of multidisciplinary approaches for determining the age and extent of stratigraphic sequences on the Delmarva Peninsula and emphasize the chronological value of cultural materials that are often overlooked. More importantly, this analysis raises questions about the types of processes that would have led to increased eolian transport over such a broad area (i.e., tidal amplitude changes from a shallowing Chesapeake Bay, climatic changes, and natural and/or anthropogenic fires).