ABSTRACT
Erosion on the order of 3 to 5 ft per year occurred at Fire Island, New York, from 1959 to 1969. Surveys made during 1970 show that a maximum in excess of 65 ft of landward erosion occurred from July to December within a part of the study area. These same 1970 surveys show approximately 56,800 yd3 of material was eroded from the dune system and approximately 18,000 yd3 of material was eroded from the berm along a 1660 ft section of beach.
Wave action is most directly responsible for the erosion. Longshore transport of beach sediment is an important process on eastern Fire Island which moves beach sediment out of the area after it has been eroded by wave action. Wind action does not directly influence erosion, and most dunes are stabilized by vegetation. Neither berm, dunes, nor dune vegetation within the study area were altered by humans or beach vehicles during 1970.
Major factors which may be controlling erosion at Fire Island and other east coast beaches are: (1) number of hurricanes and other severe storms (2) eustatic rise in sea level (3) interference of natural shore processes by man, and (4) lack of available beach material due to natural causes.
Dunes, berms, washover fans, beach cusps, and beach scarps occur on Fire Island and each responds to erosion. Sedimentary structures of particular geomorphic features (dunes, berms, washover fans) are diagnostic of their depositional environment.
Erosion is variable, depending upon crescentic shoreline form position and probably offshore topographic configuration. Crescentic shoreline forms are relatively stable under conditions which normally result in erosion to straight portions of the beach.
Fire Island is currently undergoing ravinement. The shallow marine facies is transgressing landward while the lagoonal and dune facies are being reworked by wave action.
