Miocene rocks in the North Carolina Coastal Plain are usually ascribed 

 to the Yorktown or Duplin Formations which are probable near-time 

 equivalents. Various investigators have correlated these formations 

 to either late Miocene or Pliocene age (see Campbell, 1975) . 



Fauna in cores 95 and 96 do not correlate closely in terms of 

 dominant species with any of the described fauna from either the middle 

 to late Miocene or Pliocene strata on the adjacent coast; however, in 

 general they appear to be most consistent with a middle Miocene age. 



g. Plio-Pleistocene Bioclastic Calcareous Sediments and Rocks . 

 Distinctive bioclastic carbonate sediments and rocks comprising sediment 

 type G, and correlating with the ancient channel-fill deposits of reflec- 

 tion unit IV, are judged to be largely the product of a single deposi- 

 tional event. The lithologic character of these deposits and included 

 fauna suggests that deposition occurred in a warm, shallow sea during 

 late Tertiary or Pleistocene time. 



The Plio-Pleistocene material is found in shallow subcrops and out- 

 crops in both Long and Onslow Bays; however, it is far more extensive 

 in the latter area. Since no cores taken north of Moores Inlet in Onslow 

 Bay contained this material, the northern limit of the deposit may be in 

 that locale. The extensive rock outcrops reported in the inner and mid 

 shelf area of southwestern Onslow Bay (Cleary, 1968; Cleary and Pilkey, 

 1968) are likely exposures of Plio-Pleistocene rocks possibly mixed with 

 consolidated facias of Oligocene material. 



Large numbers of individual particles in the deposits are not identi- 

 fiable because of fragmentation and recrystalization. However, a sub- 

 stantial amount of the material is skeletal parts of various marine 

 invertebrates; the unidentified particles are probably similar material. 

 Of the larger particles, the most abundant are acorn barnacle plates and 

 fragmented zooaria of bryozoans. Smaller recognizable particles consist 

 mostly of foraminifera and echinoid spines. Mollusk shells are commonly 

 present but in such a highly fragmented state that few are identifiable. 



The Plio-Pleistocene deposits can be readily differentiated from 

 other deposits in the study area by their distinctive white to light-gray 

 color, the abundance of barnacles and bryozoa in the constituent particles, 

 and by foraminiferal fauna. The only similar material found in the study 

 area is the Eocene bryozoan hash which occurs in eastern Long Bay. The 

 Eocene deposits have no barnacle plates and they differ in foraminiferal 

 fauna. Foraminifera in the Plio-Pleistocene rocks and sediments have 

 been partially recrystalized and coated with various amounts of calcareous 

 material. The identified fauna are long ranging and do not clearly indi- 

 cate the time of deposition. On the basis of available faunal data, 

 however, the most probable age appears to be Pliocene. 



Characteristics and ubiquituous benthonic foraminifera found in the 

 Pliocene deposits are Planulina depressa (d'Orbigny), Cibioides lohatulus 

 (Walker and Jacob), and Textulavia gramen d'Orbigny. Among the sparse 

 planktonic species, Glohigevnoides in^&er (d'Orbigny) is most common. 



