LATE QUATERNARY AND EARLY HOLOCENE FOSSILS FROM NEW YORK CITY BEACHES: IMPLICATIONS FOR STABILITY IN COASTAL ENVIRONMENTS IN WESTERN LONG ISLAND AND NEW JERSEY

Concretions that preserve early Holocene fossils frequently wash ashore on ocean beaches in the New York City region (coastal Long Island and New Jersey). Coastal erosion and possibly dredging are exposing fossiliferous concretions to currents that transport and deposit the material onto beaches. The fossils they contain include both normal marine and brackish water invertebrates, plant material, and bone from terrestrial and marine animals. Concretions from Rockaway Spit in Queens, NY and Sandy Hook Spit in Monmouth County, NJ were examined. The Rockaway Spit locality yielded oysters, gastropods, scallops, crabs, and plant material in a silty matrix, consistent with brackish intertidal creek or restricted bay environments. Concretionary material from New Jersey beaches is dominated by littoral and open bay faunas including gastropods, clams, jingle shells, slipper shells, scallops, crabs, lobster, and encrusting corals and sponges. In addition, the matrix is coarser grained and frequently preserves cedar roots. An oyster shell from a New York concretion yielded an age of 7,610 ±150 14C years BP. The fossil assemblages are similar to the modern fauna in some locations in the New York City region, with some notable exceptions. Some shelled organisms that are common in modern New York bays and ocean beaches are absent from the concretion fauna, most notably the shells of surf clams that often cover area beaches. All fossils represent species that are common in the Mid-Atlantic region today, with the exception of American walrus, which only survives today in northern Canada and Greenland maritime regions. Fossil taphonomy of the concretionary material is consistent with processes in modern local depositional environments, and implies the occurrence of major coastal flooding or storm events in the past.