tracers (Grabert, 1971; Colbourn and Resign, 1975). Several species of 

 foraminifera in the study area are unique to specific sediment units. 

 Their occurrence elsewhere indicates either vertical mixing or the erosion 

 and transport of material from the parent unit. Those species with rela- 

 tively large and robust tests are best adapted to use as natural tracers 

 because they are more likely to survive long transport than smaller and 

 more delicate types. In addition, small species and those with easily 

 transported tests (e.g., the planktonic types) are apt to be winnowed 

 and widely dispersed by a weak flow which may not transport the matrix 

 material . 



The lists of common species of foraminifera in Appendix E indicate 

 the abundant and unique types which might be best suited for natural 

 tracers, provided test size and durability are satisfactory. Such species 

 as the large and distinctive Cihicides flor>idana Cushman in the Miocene 

 deposits at core 96 and Nonion advenim Cushman occurring in abundance in 

 the Oligocene deposits underlying the inner shelf are examples of species 

 which may provide useful information on shelf sediment movement and 

 sources. Both have been found in more recent deposits of the shelf floor 

 where they have been incorporated after erosion and transportation from 

 the parent unit . 



Some general indications of regional transport patterns and the depth 

 of vertical mixing of substrate elements into modern shelf sediments 

 could be obtained by a more detailed study of the occurrence of displaced 

 foraminiferal fauna in the ICONS core samples. However, a more comprehen- 

 sive sediment sampling program would be needed to obtain detailed knowl- 

 edge of shelf transport patterns by this m.ethod. Such sampling might 

 prove worthwhile for a future need for information on sediment movement 

 in specific locales. 



VI . SUMMARY 



The inner shelf off southern North Carolina was surveyed to obtain 

 data on sand resources and engineering geology. A total of 824 kilometers 

 (512 statute miles) of seismic reflection survey and 134 cores ranging 

 from 0.6 to 6.1 meters (2 to 20 feet) in length were obtained. 



The inner shelf floor is topographically subdued except for prominent 

 shoals off Cape Fear and Cape Lookout. The shoreface is well developed 

 in most places and distinctly steeper in slope than the shelf floor. The 

 inner shelf is underlain over much of the study area by distinctive seis- 

 mic units which can be recognized by their characteristic internal reflec- 

 tors and mode of occurrence. Correlation of these reflection units with 

 core data indicates that the most extensive are of Cretaceous and Oligo- 

 cene age. 



Surficial and shallow-subbottom sediments consist mostly of quartz 

 sand, biogenic calcareous sand, clay, silt, biogenic clalcareous rock, 

 limestone, and sandstone. Most of these sediments are of Late Cretaceous, 

 Tertiary, and Pleistocene age. Holocene sediments are, in general, thin 



