Holocene-Pleistocene stratigraphy of the inner shelf off Fire Island, New York; implications for barrier-island migration

Prevailing hypotheses pertaining to the migrational behavior of the south shore of Long Island barriers are examined, and a more supportable hypothesis is advanced based on existing and new geophysical data. Intermittent landward migration by shoreface retreat is responsible for barrier-island migration from at least the mid-Holocene period. Concave features interpreted to be relict Holocene tidal-inlet-filled channels were found throughout the inner-continental shelf off Fire Island in depths from -12 to -30 m below mean sea level (MSL) approximately 1 to 7 km offshore. Additional supporting evidence for intermittent landward migration by shoreface retreat includes preservation of back-barrier deposits on the inner shelf, presence of linear shoals across the shoreface and shelf, and a continuous low-angle Holocene-Pleistocene interface.