TROPICAL STORM IRENE AND HURRICANE SANDY GENERATED UPPER FLOW REGIME STORM DEPOSITS, LONG ISLAND BARRIER BEACHES, NEW YORK

Storm surge during Tropical Storm Irene on August 28, 2011 and Hurricane Sandy on October 29, 2012 produced sequences of upper flow regime bedforms on the back berm of Long Island, New York barrier beaches at Smith Point of Fire Island, Robert Moses of Fire Island, Jones Beach State Park of Jones Beach Island, Lido Beach of Long Beach Barrier Island, and Breezy Point of the Rockaway Peninsular. Storm surge scours the substrate and deposits well sorted to moderately well sorted heavy mineral enriched sand in upper plane beds superimposed by antidunes. Up to five cycles of scour and upper flow regime deposition are recorded in Hurricane Sandy and three cycles in Tropical Storm Irene stratigraphy. In Hurricane Sandy deposits upper plane beds are thickest (5 cm) in the lowest sequence and thinnest (<1 cm) in the upper sequence. The antidunes are symmetrical convex upward waves with internal laminae mostly parallel to the form or low-angle upstream-dipping laminae to the south, have short wave heights (2-15 cm, average 5.9 cm), and variable wave lengths (12-35 cm) within an event layer. Antidune crests are commonly truncated and troughs are filled with concentrated heavy mineral deposits. In addition, deeply irregular scoured substrates are filled with chaotic storm deposits of angular, subangular and rounded quartz sand clasts floating in a heavy mineral enriched matrix. These intraclasts are derived by erosion of either the back berm or primary dunes proximal to deposition. Tropical Storm Irene deposition includes a thick upper plane bed, two to three sequences of upper plane beds superimposed by antidunes, or an invertebrate shell debris layer. Irene and Sandy upper flow regime storm deposits are separated by very finely laminated to sublaminated quartz rich felsic sand. This fair weather deposit has variable thickness (42-12 cm) which decreases westward from Smith Point to Breezy Point.