(e) descriptions of 26 cores ta'.en along two 5-mile 

 (8 kilometers) transects off Cedar Beach supplied by Alpine 

 Geophysical Associates, Incorporated. 



Core descriptions for most of these data are in Appendix A. 



4. Geographic Setting . 



Long Island, situated within a prominent reentrant (New York Bight) 

 on the Atlantic coast, is an elongated east-west oriented island approxi- 

 mately 120 miles (193 kilometers) long and 25 miles (40.2 kilometers) wide. 

 Long Island is separated on the north from the New England mainland by 

 Long Island Sound, bounded to the east by Block Island Sound and on the 

 south by the Atlantic Ocean. New York City is located to the west. Long 

 Island lies within the Coastal Plain physiographic province and marks the 

 southern boundary of Pleistocene glacial advance in the eastern part of 

 the North American Continent. Two end moraines form the physiographic 

 backbone along the northern part of Long Island and are partly responsible 

 for land relief along the north shore in excess of 350 feet (106.7 meters). 

 The moraines are superimposed along the western half of Long Island but 

 are sharply bifurcated in west-central Long Island. Each moraine forms 

 the core of the two peninsulas of eastern Long Island which diverge around 

 Great Peconic Bay. The northern moraine (Harbor Hill) projects offshore 

 at Orient Point and continues past Plum Island and Fishers Island obliquely 

 toward the Connecticut-Rhode Island coast. These elongate islands are 

 separated by overdeepened waterways. The Ronkonkoma Moraine on the south- 

 ern peninsula extends parallel to the Connecticut mainland east to Montauk 

 Point and then is submerged by the Atlantic Ocean. Eastward continuation 

 of Ronkonkoma Moraine is responsible for most of the relief and steep 

 cliffs of loose soil on Block Island, Martha's Vineyard, and Nantucket 

 located east of Montauk Point and south of Cape Cod, Massachusetts. 



The land surface of Long Island exhibits greatest relief on the 

 northern side and gently slopes southward where it intersects the 

 Atlantic Ocean. Shallow brackish-water lagoons and low relief sandy 

 barrier islands with associated dunes are the dominant landforms along 

 most of the southern shore of Long Island. The flat terrain south of 

 the two moraines originated as glacial outwash plains, and is composed 

 of sand and gravel detritus transported south by melt-water streams 

 during Pleistocene time. The back-barrier lagoons and elongate-barrier 

 islands are geologically very recent features which owe their origins to 

 coastal processes operating during the gradual worldwide rise in sea 

 level. The barrier islands are constructional landforms built up over 

 the past several thousand years by sand from the sea floor and by sand 

 transported westward along the Long Island shoreface by wave-generated 

 longshore currents. This chain of sandy barrier islands extends from 

 the western end of Long Island eastward to Southampton (Fig. 2) and is 

 presently broken in continuity by six tidal inlets. Historically, most 

 inlets on the south shore have migrated westward, some very rapidly such 

 as Fire Island and Rockaway, in response to the predominantly westward 

 longshore transport of littoral materials (Taney, 1961). These inlets 



15 



