continuous sand thickness in feet for each respective core. Sediment 

 descriptions and some granulometric analyses for these cores are in 

 Appendixes A and B. The sediment thickness values shown in Figures 27, 

 28, and 29 were then extrapolated to peripheral parts of the borrow areas 

 by sea floor sediment trends and by correlation of the sediment stratig- 

 raphy in the cores with stratification lines on the seismic profile 

 records. Based on these data, minimum sand thicknesses and potential 

 thickness were calculated for each borrow area. The potential thickness 

 is considered to be a reasonable value for which limited core data exist; 

 however, based on the seismic profiles it is highly probable that these 

 potential sand volumes are less than what could be proven available if 

 longer cores were taken. Because the cores used for this report are a 

 maximum of 20 feet (6 meters) long (except area M) , 20 feet is the maxi- 

 mum potential thickness. However, the seismic profiles, especially along 

 the eastern Long Island Atlantic shelf, indicate that greater thicknesses 

 of sand exist below the limits of core recovery. Much deeper cores would 

 be necessary to substantiate the presence of deeper sand, but volumes cal- 

 culated from cores in this report indicate that further exploration may be 

 unnecessary to satisfy presently anticipated needs for beach restoration. 



Each of the 14 borrow areas was planimetered to calculate the area 

 in square yards and this figure was multiplied by both the minimum and 

 potential sand thicknesses to yield the sand volumes in Table 5. 



a. Area A (Gardiners Bay] . Area A is small and circular and is 

 located immediately west of Three Mile Harbor (Fig. 27). The sea floor 

 surface dips gently northeast beyond the 30- foot (9.2 meters) depth con- 

 tour. Only core 3 is in area A, but it shows the entire length (9 feet; 

 2.7 meters) is clean, fine to medium sand. The seismic records show the 

 sediments are flat lying but pinch out abruptly at the eastern boundary 

 where muds cover the upper parts of the ancestral Three Mile River channel. 



b. Area B . Area B lies east of Three Mile Harbor and is slightly 

 smaller than area A (Fig. 27). Core 6, the only core in area B, contains 

 clean medium sand overlying coarse sand with pebbles down to a depth of 

 8.5 feet (2.6 meters) below the sea floor. Deeper core penetration was 

 probably prohibited by the coarse sediment, and the seismic records show 

 no apparent change in lithology down to 15 feet (4.6 meters). The bound- 

 ary limits for this area are arbitrary but the four surrounding cores 

 show that this is an isolated pocket of sand surrounded by muds (type V 

 sediment) . 



c. Area C . This area is on the northern side of Gardiners Bay imme- 

 diately south of Plum Island (Fig. 27). Core 1, the only core available, 

 contains 6.7 feet (2.1 meters) of sand overlying very fine silty sand, 

 organic peat, and cohesive clay. It is in 39 feet (12 meters) of water 

 on the east bank of the submerged Plum Gut depression. Since the seismic 

 records show the sand layer thickens toward Plum Island, it is possible 

 that more than the indicated 3 yards (2.7 meters) (Table 5) are present 

 and that suitable sand extends farther east than is shown by the boundary. 



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