the Long Island dates has the same general slope as the curve for lona 

 Island and is reasonably close to the extrapolated curves for both Cape 

 Cod and New Jersey. The date for core 14 plots far below the curve and 

 is probably spurious due to inherent problems in accurately dating bulk 

 samples of organic mud. The two dates for core 1 and the date for core 

 2 plot above the curve, but because both cores are from Gardiners Bay, 

 close to the Pleistocene ice margin, they may indicate that consequent to 

 retreat of the glaciers the land area rebounded a maximum of 15 feet (4.6 

 meters) before mid-Holocene time. The curves in Figure 25 also indicate 

 that although sea level may have fluctuated slightly, there is an overall 

 indication of a progressive marine transgression during the past 8,500 

 years . 



IV. SANDFILL NEEDS AND RESOURCE POTENTIAL 



1. Sandfill Requirements for Area Beaches . 



The shoreline along the Atlantic coast of Long Island is one of the 

 most heavily attended recreation areas in the United States. The total 

 annual attendance for the major beaches along the south shore of Long 

 Island is about 57 million people, but these same beach areas are expe- 

 riencing critical erosion problems (U.S. Army, Corps of Engineers, 19 71). 

 This same report indicates that 300 miles (483 kilometers) of Atlantic 

 coastline in New York State have been categorized as having undergone 

 critical erosion. Shore erosion is defined as critical when the magni- 

 tude of shoreline recession is significant and when the benefits expec- 

 ted from corrective actions needed to curtail erosion would justify costs 

 of such improvements. For the south shore alone the estimated annual 

 change to public and private property and development from shore erosion 

 is $9 million (U.S. Army, Corps of Engineers, 1971). 



Several Federal Beach Erosion Control and Hurricane Protection pro- 

 jects for the south shore of Long Island are authorized or have been 

 recommended to the Congress by the Corps of Engineers. Figure 26 shows 

 the project segments by order of priority set by the U.S. Army Engineer 

 District, New York. The Jones Beach and Montauk sectors are the only 

 areas where shoreline recession is not considered to be critical at pres- 

 ent and no priority has been set. Since the needs and availability for 

 sand at Rockaway Beach are considered by Williams and Duane (1974), they 

 are not discussed in this report. The numbers for each segment are the 

 sandfill volumes thought to be necessary to satisfy the dune and beach- 

 fill requirements for that part of the project. A project generally 

 involves an initial fill and then periodic renourishment during a 50-year 

 period estimated as the reasonable economic life over which to amortize 

 costs and compare benefits. The total sand needed at present to initiate 

 all these projects (excluding Rockaway) is more than 61 million cubic 

 yards (47 million cubic meters), and that needed to complete the 50-year 

 projects is an additional 75 million cubic yards (60 million cubic meters) 

 Thus, the total volume of sand necessary to complete all projects for the 

 south shore is estimated to be 136 million cubic yards (107 million cubic 

 meters) . 



65 



