Brown, Miller, and Swain (1972) did not differentiate rocks of post- 

 middle Miocene age in their study of Atlantic Coastal Plain geology. 

 Onshore geologic formations that have generally been ascribed a late 

 Miocene or Pliocene age in the southern North Carolina Coastal Plain are 

 the Duplin Formations of probable early to middle Pliocene age and the 

 Waccamaw of probable late Pliocene age (Campbell, 1975). 



h. Quaternary Deposits . Most of type A, D, E, and F deposits are 

 sediments of apparent Quaternary age, but possibly contain late Tertiary 

 elements. Except in shoal areas, the Quaternary deposits are rarely 

 thick enough to be identified or traced on available seismic reflection 

 records and their distribution and character are known only from the 

 core data. 



Type E shelly sands and shell gravels are believed to be the oldest 

 of the Quaternary deposits. They are heterogeneous and probably not all 

 the product of a single depositional episode; however, most seem to have 

 been deposited in a shallow, marginal marine environment probably near 

 the leading edge of the transgressing Holocene sea or during the mid- 

 Wisconsin recession. The shell content of type E sediments consists of 

 a mixture of skeletal fragments derived mostly from mollusks but also 

 containing bryozoa, echinoids, and barnacles; calcareous algae and coral 

 occur locally in small quantities. The disparate nature of the fauna 

 and the wide variation in the condition of shell particles indicate that 

 the sediment contains reworked and detrital biogenic elements as well as 

 those resulting from in situ production. Some mollusk shell fragments 

 appear to be from Tertiary species. In most cases, these shells are 

 badly worn and their presence with modern, well-preserved shells suggests 

 detrital origin. The Tertiary material is dominant in a few places; these 

 deposits may be of late Tertiary age. 



The most common and ubiquitous mollusk found in type E sediment is 

 the coot clam, Mulinia lateralis Say, an abundant inhabitant of marginal 

 marine waters. Other locally common species are Anadara transversa {Sa-y), 

 Crassinella lunulata Conrad, Gemma ^emma (Totten), Crassostrea virginioa 

 Gmelin, Nucula proxima Say, and Nuoulana acuta (Conrad) . 



Foraminifera are usually abundant in type E deposits. Species of 

 Elphidium, Ammonia, and ■■dM-inqueloaulina typically dominate the assemblages. 

 In some places, there are numerous Hanzaidaia aonoentrioa Cushman, suggest- 

 ing deposition in somewhat deeper waters than now exist over the inner 

 shelf. However, for the most part the assemblage indicates deposition 

 in marginal marine conditions. A distinctive assemblage of abundant 

 Elphidium gunteri Cole occurs in several cores from southern Onslow Bay 

 and these may be from a single extensive deposit. Elsewhere, the deposits 

 appear to be more localized. 



The type F clay and sandy clay deposit is also believed to be Quater- 

 nary in age on the evidence of its position relative to other units. 

 Except for plant fragments, samples of this deposit contain little or 

 no in situ fossils. It is apparently a shallow estuarine, marsh, or 



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