1973). These sources indicate that desirable borrow sand for beaches in 

 this region should be in the medium to coarse sand range (Q.25Q to l.OQ 

 millimeter, 2. to 0.0 phi). Selection of the borrow sites described 

 below is based mainly on that size criterion. 



2. Potential Borrow Areas . 



Two groups of potential offshore borrow locations are: (a) Areas for 

 which there are sufficient data to delineate the probable area extent and 

 sand volume of the deposit (designated as borrow areas A, B, C, and D) ; and 

 (b) potential borrow sites for which there are insufficient data to deline- 

 ate the deposit or calculate volume, but which are shown by cores to con- 

 tain suitable material (identified by core number) . Borrow areas and core 

 sites are described in the Table and plotted in Figures 2, 3, and 4. 



a. Borrow Area A . Borrow area A (Fig, 2) consists of the larger part 

 of Middle Ground Shoal lying immediately seaward of the Cape Fear River 

 entrance; center coordinates are 33°52.7' N. , 78°01.7' W. 



Figure 5 is an isopach map of Middle Ground Shoal based on bathymetric 

 data and cores. The volume of sediment within the zero isopach contour is 

 71 million cubic yards, the bulk of which is clean quartz sand in the fine 

 to medium size range (0.125 to 0.250 millimeter, 3.0 to 1.0 phi). To 

 minimize adverse effects of shoal removal on the shoreline, U.S. Army 

 Engineer District, Wilmington (1973) indicated only so much of the shoal 

 should be removed which would leave the resultant bottom profile equivalent 

 to the shoreface slope of the open-coast beaches to the west. With this 

 adjustment the potential volume of sand available in the borrow area is 

 judged to be 50 million cubic yards (38 million cubic meters). 



b. Borrow Area B . Borrow area B consists of that part of Frying Pan 

 Shoals extending from Cape Fear to 16 nautical miles (29.7 kilometers) 

 offshore (Fig. 2). Figure 6 is an isopach map of the borrow area drawn 

 above a reflector that passes beneath the shoal at about the elevation of 

 the surrounding shelf floor. Because of sparse reflection and core 

 coverage of areas adjacent to the shoal, the zero isopach contour cannot 

 be established with reliability. Therefore, volume calculations were 

 made using the IQ-foot isopach contour as the datum. These calculations 

 show that approximately 1.4 billion cubic yards (1.1 billion cubic meters) 

 of sediment is contained in the shoal. Cores indicate that most of the 

 shoal sediment consists of quartz sand containing about 15-percent biogenic 

 calcium carbonate derived chiefly from mo Husks, echinoids, and Foramini- 

 fera. Most of the sand recovered in nine cores of the shoal area is in 

 the fine size range (0.125 to 0.250 millimeter, 3.0 to 2.0 phi); however, 

 four cores contain medium to coarse sand. Three of the cores (58, 61, and 

 62; Fig. 6) are in relatively close proximity and apparently lie within 

 the bounds of the same deposit. The coarser texture of this material may 

 be related to the relatively shallow water (<40 feet) of the shoal crest. 



In terms of size distribution and quality, the best beach replenish- 

 ment material in Frying Pan Shoals is in the general locale of cores 58, 



12 



