No cores were taken in Lookout shoals during the ICONS survey. Mixon 

 and Pilkey (1976) report sand in the Cape Lookout shoals to be a "fairly 

 well sorted, light-gray to yellowish-gray, fine to medium sand" with a 

 mica content of 20 to 40 grains per 10,000 and a calcareous fraction of 

 generally less than 5 percent. 



5. Relict-Modem Sediment Boundary . 



The distribution of relict and modern sediments, along with the areal 

 and vertical location of the boundaries between these sediment bodies, is 

 an important aspect of engineering site investigations of the shelf floor. 

 For example, fixing the vertical boundary between modern, and possibly 

 mobile, surface sediments and underlying relict strata is important in 

 the subsoil analysis of shelf floor foundation properties. 



Because many modem surficial sediments of the inner shelf floor are 

 lithologically similar to the underlying substrate, from which in many 

 cases they are derived by reworking (Swift, Stanley, and Curray, 1971), 

 it is often difficult to determine the boundary by gross lithology or 

 mineralogy alone. In such cases, faunal components of the sediment 

 bodies are the most useful in delineating the boundary. In most cases, 

 the relict deposits contain fauna with extinct elements or, if the deposit 

 is of Quaternary age, fauna that originated under different environmental 

 circumstances and is clearly exotic in the present environment. Even 

 where there is considerable mixing across the boundary, the mixed, modem- 

 relict assemblages can usually be discriminated from the wholly relict 

 assemblage of the substrate. 



The areal distribution pattern of relict and modern sediments in the 

 Cape Fear region does not conform to the classic onshore-offshore zonal 

 arraignment with modern paralic sediments dominant inshore and relict 

 sediments offshore. The distribution is much more complex. The inner 

 shelf floor contains numerous and extensive areas of relict sediment 

 interspersed with modem marine sediments. Even in the shoreface zone, 

 where modern sediments probably dominate, there are known outcrops of 

 Tertiary carbonate rock near New River Inlet (Lawrence, 1975; Crowson and 

 Riggs, 1976). 



The most distinctive relict deposits exposed on the shelf floor are 

 Plio-Pleistocene calcareous sediment and rock (type G) . This material 

 contrasts sharply with the quartz sand and shelly sand deposits charac- 

 teristic of the modern shelf sediments. Other relict outcrops, especially 

 the fine quartz sands (types B and C) of late Cretaceous and Oligocene 

 age, are less distinct lithologically from modern deposits but are identi- 

 fiable by the included fauna. 



More subtle distinctions occur where there are shelf floor outcrops 

 of relict sediments deposited during the Holocene transgression. Although 

 these deposits were placed in water shallower than now prevails over the 

 area, much of the relict faunal content is derived from organisms with a 

 wide enough bathymetric range to have existed at the present water depth. 



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