GEOMORPHOLOGY, SHALLOW SUBBOTTOM STRUCTURE, AND SEDIMENTS OF THE 

 ATLANTIC INNER CONTINENTAL SHELF OFF LONG ISLAND, NEW YORK 



by 

 S. Jeffress Williams 



I. INTRODUCTION 



1. Background . 



Ocean beaches and associated dunes provide a necessary and important 

 buffer zone between the sea and fragile coastal wetland areas for many- 

 continental land masses. At the same time, beaches provide public recrea- 

 tion areas for millions of people. The construction, improvement, and 

 periodic maintenance of beaches and dunes by placement of suitable sand 

 along the shoreline can be an in^ortant means of counteracting coastal 

 erosion by providing stability to shoreline positions and permitting 

 recreational facilities (U.S. Army, Corps of Engineers, 1971). Beach 

 nourishment techniques (Hall, 1952) have gained prominence in coastal 

 engineering largely as a result of the successful beach nourishment test 

 program using a hopper dredge at Sea Girt, New Jersey, in 1966 by the 

 U.S. Army Engineer District, Philadelphia (1967); and the successful com- 

 pletion of the nourishment of Redondo Beach, California, in 1969 by com- 

 mercial operator under contract to the Corps of Engineers (Fisher, 1970). 

 Artificial beach nourishment using offshore sand was also successfully 

 conducted at five beaches on the southeast coast of Florida (Strock and 

 Noble, 1975). A major restoration of Rockaway Beach on western Long 

 Island, New York, is presently underway. Approximately 4 million cubic 

 yards (3 million cubic meters) of sand has been dredged from East Bank 

 shoal (offshore Coney Island) and transported by pipeline to the beach 

 (G. Nersesian, U.S. Army Engineer District, New York, personal communica- 

 tion, 1975). These projects show that present technology is advanced 

 enough to make sand and gravel on the shallow parts of the shelf a pres- 

 ently exploitable resource (Duane, 1968) and (at some locations) econom- 

 ically competitive with existing methods (truck haul and drag scoop) for 

 sand transport and beach construction. 



Plans for initial beach restoration and periodic renourishment usually 

 involve large volumes of suitable sandfill. In recent years it has become 

 increasingly difficult to obtain suitable sand from lagoons and wetlands 

 or from inland sources in sufficient volumes and at an economical cost 

 for beach fill purposes. These difficulties have resulted in part from 

 increased real estate values, concern over environmental and ecological 

 effects of removing such large volumes of sand, diminution or depletion 

 of previously used land sources, and inflated transportation costs of 

 moving the material from areas increasingly remote from final destina- 

 tions. In addition, sedimentary material comprising the bottoms of 

 wetlands, i.e., lagoons, estuaries, and bays, is mostly fine-grained 

 and rich in organic content, and as a result, is unsuitable for long- 

 term effective shoreline protection. While the loss of some fine-grain 

 material is to be expected as a newly nourished beach attains a new state 



