organics for radiocarbon age dating. The sand included in the "atypical" 

 (of this locale) sediment category is a white, medium-sized, well -sorted 

 quartz sand. The sand is much whiter than type I sands and contains a 

 much less diverse mineral assemblage. Heavy minerals, glauconite, and 

 mica are nearly absent. A very coarse sand, or gravel, was noted in one 

 core (33) . Diagnostic of this sediment is its red color (fine-grained 

 limonite), weathered silicate grains, abundance of rock fragments, and 

 complete absence of fauna. The sand is poorly sorted to very poorly 

 sorted; the overall size of the deposit ranges from clay to cobbles. 



3. Surface and Subsurface Sediment Distribution . 



a. Spatial Nature of the Surface Sand Body . The dominant grain size 

 of surface sediments of the U.S. Atlantic Inner Continental Shelf is sand 

 (Trumbull, 1972; Milliman, 1972). These sands have been interpreted as 

 dominantly relict-fluvial in origin (Emery, 1968) with modern sands re- 

 stricted to a nearshore band (Milliman, 1972). Swift, et al . (1971) 

 pointed out that although inner shelf sands bear mineralogic and faunal 

 evidence of deposition in other environments, they have been partially 

 reworked and their textural characteristics reflect their response to the 

 present marine environment. They coined the term "palimpsest" to describe 

 these sediments. The spatial nature of these shelf sands is generally 

 unknown . 



The term "surficial sand sheet" has been commonly used in reference 

 to the mantle of sand covering the inner shelf (e.g., Swift, 1970). This 

 term is somewhat misleading, as recently discussed by Field and Duane 

 (1976), for it connotes both a specific geometry (as defined by Krumbein 

 and Sloss, 1963) and certain uniformity or continuity. When examined by 

 dense sampling patterns, most shelf areas show a high degree of variabil- 

 ity in texture of surface sediments. In areas characterized by irregular 

 topography, such as the study area, distribution of surface sediment 

 types is often controlled or strongly influenced by the local shelf mor- 

 phology (Fig. 24) . 



The dominant surface sediment in the study area is medium- to coarse- 

 grained, clean sand (type I). Poorly sorted fine sands and gray muds 

 (types III and IV) account for only 10 to 14 percent of the samples, and 

 these are all from swales or intervening flat areas between shoals. 

 Clean, fine sands are also relatively uncommon in surface samples (11 

 percent) and are generally restricted to the shoreface-shoal complex in 

 the southern part of the study area. It is quite evident that any attempt 

 to "contour" or group similar sediment types, without considering their 

 relation to the local topography, could easily lead to erroneous con- 

 clusions. Sediment distribution is a function of the shape of the sea 

 floor, and unless the sample population is very dense, interpolation of 

 shoal sands across a swale area is not justified. 



b. Shallow Subsurface Sediments . The distribution of sediments in 

 the shallow subsurface is markedly different than on the surface, except 

 in the vicinity of shoals, where surface sands are thicker (Fig. 25). 

 Clean sands are still relatively common at the shallow sediment depth of 



59 



