INTERMITTENT GROWTH OF A BARRIER SPIT IN THE US ATLANTIC COAST DRIVEN BY HURRICANE ACTIVITY IN WESTERN NORTH ATLANTIC ON CENTENNIAL TIMESCALES

Understanding the long-term response of sandy coasts to changes of storm climate is critical to managing such dynamic environments. Paleotempestology records have shown century-long variation in storminess in the Atlantic basin during the late Holocene, but it has been rare to investigate the corresponding response of sandy coasts due to the difficulty in establishing chronologies at relevant timescales. Here we present the 2.4 kyr history of the Cape Henlopen barrier spit in southeastern Delaware Bay based on vibracoring, ground-penetrating radar (GRP) stratigraphy, and optically stimulated luminescence (OSL) dating to investigate its relationship with storm activity in the Western North Atlantic. The GPR stratigraphy indicates that the spit builds on top of a spit platform and grew primarily through linear downdrift extension. The OSL dating shows stratigraphic consistency and agreement with existing ¹⁴C constraints on the age of the spit. Clustering of the OSL data demonstrates that the spit formation began around 2.4 ka and has major advances between 1.9-1.5 ka and around 0.5 ka. These periods of major advances correspond to increases in hurricane activities in the Western North Atlantic. This finding, in agreement with a few recent studies, supports the idea that storminess plays a critical role in the growth of barrier spit at centennial timescales. Intensification of storms due to global warming over the next century will probably accelerate both updrift erosion and downdrift extension along sandy barrier spits.