Perlmutter and Todd (1965) showed that the landward limit of the 

 Gardiners Clay is about 8 miles (12,9 kilometers] north of Fire Island 

 beach (Fig. 2) . The thickness of the formation is 10 to 25 feet (3 to 

 7.6 meters) with a surface elevation of 50 to 100 feet (15.2 to 30,5 

 meters) below sea level. Further possible extension of the Gardiners 

 Clay and upper Pleistocene-Holocene stratigraphy offshore across the 

 Long Island inner shelf is covered later in this report. 



Most investigators of Long Island stratigraphy agree that late Wis- 

 consin glaciation is represented by two prominent ice margin moraines. 

 Both deposits consist primarily of stratified sand, silt, and gravel; 

 however, sediments from lacustrine and fluvial environments are also 

 common (Fleming, 1935) . The two moraines are difficult to differentiate 

 in western Long Island because the Ronkonkoma is absent or the Harbor 

 Hill covers it; however, observations from eastern Long Island, where 

 the moraines bifurcate, show that the Harbor Hill Moraine is separate 

 from and younger than the Ronkonkoma Moraine. The land south of these 

 moraines is comprised primarily of outwash sand and gravel which was 

 carried southward over the exposed shelf by the numerous, melt-water fed, 

 braided streams during Pleistocene. The time marking the end of Pleis- 

 tocene continental glaciation and the start of the Holocene transgression 

 of the sea back over the shelf is variable depending on geographic loca- 

 tion and degree of isostatic rebound, but Newman (1966) and Schaffel 

 (1971) felt that an approximate date for commencement of the marine 

 transgression for the western Long Island region is 10 to 12 thousand 

 years Before Present (B.P.)- 



6. Water Movement and Littoral Drift . 



The motion and seasonal circulation patterns of the surface and 

 bottom water masses of the nearshore Long Island region have been studied 

 only to a limited extent. Areas receiving greatest attention are the 

 inner New York Bight (western Long Island) and Long Island Sound. Infor- 

 mation for the south shore inner shelf of Long Island is sparse except for 

 estimated longshore transport rates and some water motion and current velo- 

 city measurements near the barrier inlets. 



Tides for the Long Island south shore region are semidiurnal and range 

 in height from 4.7 feet (1.4 meters) at Rockaway Inlet to 4.2 feet (1.3 

 meters) at Fire Island Inlet, and 2 feet (0.6 meter) at Montauk Point 

 (Panuzio, 1968). Tidal ranges for the lagoons are generally less than 

 values for the open ocean, averaging 2 feet. 



Because Long Island is oriented east-west in the Atlantic Ocean and 

 separated from the New England mainland by 10 to 20 miles (16.1 to 32.2 

 kilometers), it is most affected by wind-generated waves from the south 

 and southeast. Tidal forces are influential in the Block Island region 

 of eastern Long Island and around the six inlets on the south shore; 

 otherwise tidal effects appear secondary. Wind blowing over the large 

 fetches of open ocean from the southwest and southeast quadrants can 

 produce large waves. According to Panuzio (1968), a statistical study 



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