Reconstruction of Morphostratigraphy and Dynamics of Former Tidal Inlets along a Wave-Dominated Barrier Island and Impacts on Island Evolution: Assateague Island, MD-VA




Seminack, Christopher

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This dissertation is a study of former tidal inlets along Assateague Island, Maryland-Virginia. A multi-technique approach, including analysis of historical nautical charts and maps, LIDAR datasets, true-color and infrared aerial imagery, ground-penetrating radar (GPR) surveys, and analysis of sediment cores, was pursued to reveal the dynamic nature of former tidal inlets along Assateague Island. Assateague Island has experienced many breaching events throughout its history as a result of extra-tropical and tropical storm impacts. An updated inlet chronology of the mixed-energy, wave-dominated barrier island concluded that 12 former tidal inlets and breach zones were identified from north to south: Northern Assateague Breach zone, North Sinepuxent Inlet, Sandy Point Inlet, North Beach Inlet, Sinepuxent Inlet, Fox Hills and Winter Quarter Breach zone, Slough Inlet, Green Run Bay Inlet, Green Run Inlet, Cherry Tree Inlet, Swan Pool Breach zone, and Tom’s Cove Breach zone. Evidence of former tidal inlets and breaches include such geomorphic features as relict recurved-spit ridges, relict flood-tidal deltas (FTD) and flood channels, relict inlet channel scars (topographic low areas of immature vegetation), relict-inlet ponds, and relict inlet-closure ridges. Inlet-closure ridges are more subtle than recurved-spit ridges, with the tallest inlet-closure ridge at about 1.6 m, which is equivalent in height to the shortest recurved-spit ridge (1.6 m). In general, recurved-spit ridges were also documented to decrease in height toward the inlet throat within the former inlets. In total, 34% of Assateague Island is estimated to be comprised of tidal-inlet fill.



Geology, Geomorphology, Sedimentary geology, Barrier Island, Beach, Closure Ridge, Inlet, Remote Sensing, Storm