LONG ISLAND SOUND 



I 2 n mi 



I 2 3 4 kn 



slond 



LEGEND 

 Core Site 

 Seismic Profile 

 Send a.io Grovel Deposits 



Contours in ft 



V 



Figure 25. Map of borrow area M along the Long Island north shore. 



subject to strong tidal surges. Seismic line 29 shows internal stratification 

 in the deposit; core 74 to the west and core 72 on the eastern end contain 4 

 and 2.3 meters of clean, fine to coarse sand and pebbles, respectively. 

 Seismic lines 21 and 22 show that the sand thins abruptly offshore and that 

 flat-lying, fine-grained strata are present at -19.5 meters. Using a thick- 

 ness of 2.7 meters, the deposit contains an estimated 54 million cubic meters 

 of sand and gravel. 



The seismic data and core 70 to the east of area M show that stratified 

 sandy sediments continue well beyond the boundaries of area M; however, the 

 -18-meter contour is very close to shore, hence the deposits are probably 

 confined to a narrow band and removal of large quantities could adversely 

 affect stability of the adjacent coast. 



n. Area N - Long Sand Shoal . Long Sand Shoal, an elongate, slightly 

 arcuate ridge about 3.5 kilometers off the mouth of the Connecticut River has 

 a total length of 10.8 kilometers and a maximum width of less than about 450 

 meters, and tapers to the east and west. The minimum water depth over the 

 shoal is 2.4 meters and the adjacent bottom to the north is on the order of 

 12.2 meters; the bottom drops abruptly to the south to depths of 45.7 meters 

 within 1.8 kilometers of the shoal (Fig. 26). 



There are several seismic profiles that run up to and adjacent to the 

 shoal, but the extreme shallow water prevented the survey vessel from crossing 

 the shoal. In addition, cores 64, 65, 66, and 67A taken on the shoal flanks 

 provide good physical evidence of the subbottom character of the shoal. 



49 



