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Stanley R. Riggs, William J. Cleary and Stephen W. SnyderFigure 4. Photograph looking north at the Fort Fisher (A) andthe Pleistocene coquina subaerial headland (B). This photoalso shows the: (C) Pleistocene friable humate- and ironcementedsandstone that forms a two meter high wave-cutcliff; (D) rock revetment built to protect the rapidly receedingshoreline and the Civil War Fort Fisher; and (E) the strandplainbeach. Photo was taken in 1977 and the shoreline hadalready receeded behind the rock revetment; today the shorelinehas receeded an additional 20 to 25 meters.tions and cores suggest that the sediment cover is bothpatchy and very thin across much of this region and in manyareas is totally lacking.The extensive series of coquina outcrops on the innershelf act as barriers that could significantly affect the refractionof wave energy, as well as the movement of sand acrossthis shoreface. Moorefield (1978) believes that sand fromboth the rapidly eroding beach at Fort Fisher and littoraldrift, are transported seaward of the rock barrier duringstorms and prevented from returning to the beach duringsubsequent low energy periods. The result of this process is anet sediment deficiency in which the rapidly retreating bluffshoreline is consuming the historic Fort. A variance wasreceived from the State to build anew rock revetment to protectFort Fisher; the present bulkhead structure was completedin 1995.Submarine Headland Shorefaces and BathymetricHighsOnslow Beach to Topsail IslandThe New River Inlet coastal area (Fig. 1) is a submarineheadland, which forms a small seaward bulge in the coastlineof central Onslow Bay (Fig. 2). This shoreline protrusion isproduced by the Oligocene Silverdale Formation, an induratedmoldic limestone and calcareous-cemented quartzsandstone unit. The Silverdale Formation crops out at orslightly below sea level in the mouth of the New River estu-Figure 5. Schematic diagram looking southwest along the hardbottom scarps of the Oligocene Silverdale Formation that crop out onthe inner continental shelf off of Topsail Island. The scarps are parallel to and face the beach, up to 5 m high with major overhangs,and dip gently seaward. Extensive bioerosion and wave processes produce “new” gravel sediment which is transported directly tothe beach during storms. The sandy limestone crops out at sea level in the estuary behind the barrier; however, it is not known howthe barrier is perched on top of this rock unit. Figure is modified from Crowson (1980).34