strong reflector passes under the flanking terrace at or near the level 

 of the channel floor indicating that the channel floor may be continu- 

 ous with the surface of the older unit underlying the terrace sands. A 

 truncated reflector on the wall flanking the main entrance channel at 

 about -60 feet MLW (lines 8 and K) suggests that here the channel may be 

 partly the result of erosion and partly the product of upbuilding on the 

 flanks. Core 37 in the Chesapeake Channel and Core 23 near the main 

 entrance channel both show indications of deposition in shallower water 

 than presently exists over the area. Core 37 from 3 to 9 feet downhole 

 contains a foraminiferal assemblage dominated by Arenoperalla mexicana 

 indicating conditions transitional to the present environment (Nelson, 

 1969). Below 9 feet downhole, a peaty layer has been established to be 

 a near sea level deposit of transgressive Holocene age (Maynard Nichols, 

 personal communication) . 



Section IV. SAND RESOURCES 



1. Sand Volume Requirements 



The major potential sand requirement of the Corps of Engineers in 

 the region is for fill to restore and maintain Virginia Beach, Virginia. 

 Existing and recommended projects call for restoration and improvement 

 of the segment of beach between Rudee Inlet and 89th Street by placing 

 an initial fill of 2.4 million yards of sand. Maintenance will require 

 133,000 cubic yards annually plus the existing maintenance fill amount- 

 ing to 163,000 cubic yards annually now furnished by dredging from Owl 

 Creek. The total annual maintenance fill is thus 296,000 cubic yards. 

 Initial fill plus annual maintenance fill for a 50 year period will re- 

 quire 17.2 X 10^ cubic yards of suitable sand. 



2. Sand Suitability and Potential Borrow Areas . 



The suitability of borrow sand for beach restoration and nourish- 

 ment depends on several factors. Important factors are size distribu- 

 tion, composition, and economics of recovery and placement. Borrow 

 material significantly smaller in gradation than the native beach ma- 

 terial will probably prove unstable under the wave and current regimen 

 on the beach, and will be rapidly eroded. The most suitable borrow 

 sand is sand having nearly the size characteristics of the native beach 

 material. A desirable composition is one in which the particles are 

 composed of hard inorganic material such as quartz that will not de- 

 grade readily in the littoral environment. 



Within the limits of study, the collected data indicate that there 

 are only two areas with significant deposits of sand suitable for fill 

 on nearby beaches. The ubiquitous fine gray sand and sandy silt cover- 

 ing much of the bottom of the Bay Entrance contains little usable ma- 

 terial because of its fine grain size. 



37 



