was obtained below the first subbottom reflector. The top of the Eocene 

 strata is believed to coincide with the green primary reflector which 

 dips eastward from its outcrop in Long Bay under Frying Pan shoals and 

 into Onslow Bay where it can be traced as far north as New River Inlet 

 (Figs. 9 and 10). The green reflector is believed to lie at or very 

 near the Eocene-Oligocene contact for the following reasons. First, the 

 projected outcrop of the green reflector on the adjacent emerged coastal 

 plain accords well enough with the outcrop of the Eocene Castle Hayne 

 Formation (North Carolina Department of Conservation and Development, 

 1958; Stuckey and Conrad, 1958) to suggest that discrepancies are within 

 the range expected from projection error and from horizontal variations 

 in the outcrop line due to topographic relief. Second, Eocene bryozoa 

 hash occurs in several ICONS cores near the sea floor outcrop of the 

 green reflector in Long Bay. Third, elevations to the top of the Eocene 

 in several wells on the coastal plain (described in Brown, Miller, and 

 Swain, 1972), are close to the projected elevation of the green reflector 

 at the well location. 



Only three cores (C21, C31, and W07) contained foraminifera in 

 sufficient quantity and state of preservation to characterize the Eocene 

 assemblage. In these cores planktonic types are sparse, the benthonic 

 fauna are abundant and diverse; common and characteristic benthonic 

 species are Eponides cocoaensis Cushman and Cihiaides subspirata Nuttall. 



The Eocene calcareous deposits under the inner shelf probably cor- 

 relate with the rocks of Clarborne age identified in the Cape Fear region 

 (Brown, Miller, and Swain, 1972) and the Castle Hayne Formation of the 

 Carolina Coastal Plain. Brown, Miller, and Swain describe the Clarborne 

 unit in nearby wells onshore as a molluskan limestone grading laterally 

 into bryozoan limestone. Castle Hayne deposits are usually characterized 

 as calcareous sediment or rock. 



e. Oligocene Sand and Calcareous Rock . Extensive and thick deposits 

 of Oligocene age closely underlie the inner shelf of much of Onslow Bay 

 and probably extend under Frying Pan shoals into eastern Long Bay. All 

 of reflection unit III is believed to be made up of Oligocene sediment. 

 Core data indicate that Oligocene strata also lie near the surface in the 

 southern part of the reconnaissance area as far north as New River Inlet 

 and possibly beyond. 



Typically, the Oligocene sediments consist of very fine or fine, well- 

 sorted quartz sand, with biogenic calcium carbonate ranging from a few 

 percent to more than 35 percent by weight. Near New River Inlet, consoli- 

 dated calcareous rock of Oligocene age occurs in cores 98 and 99; Crowson 

 and Riggs (1976) report that calcareous rocks in this general area are 

 exposed on approximately 50 percent of the sea floor inside the 15-meter 

 isobath. 



Some of the Oligocene sediments are devoid of recognizable fossils 

 except for occasional phosphatized bones and teeth from marine vertebrates 

 (Fig. 15, a). Most of the samples, however, contain calcareous skeletal 



57 



