Table 5, there are several vertical trends in sediment patterns. Gray- 

 brown, fine to coarse, well-sorted quartz sand is the dominant lithology 

 on the surface and decreases in relative abundance with depth. Increases 

 in sand thickness occur locally in shoal areas. The sand overlies poorly 

 sorted, very fine to fine sands and muds that are locally exposed at the 

 surface and that increase in relative abundance with depth. Well -sorted, 

 fine sands are restricted almost entirely to shoreface shoals off central 

 and southern Assateague and are relatively thick. Atypical sediments 

 (white sands, brown muds, organic muds, and red iron-stained gravels) 

 are absent on the surface and occur at different levels in the shallow- 

 sediment column. The muds lie beneath clean surface sands; the sands 

 and gravels lie at the base of cores and represent the top of sediment 

 units that were rarely sampled but are probably widespread. Of equal 

 importance to distribution of sediment types is their vertical relation- 

 ships to one another, including the nature of contacts and internal vari- 

 ations such as lamination, burrows, size grading, etc. This information 

 may be obtained through careful logging and photographing of cored sedi- 

 ments . 



Core 33, collected about 20 kilometers (11 miles) offshore of Ocean 

 City in over 18.2 meters of water, is composed of five sediment units, 

 one of which is an iron-stained gravel (Fig. 29). The top 0.43 meter 

 (1.4 feet) of the core is composed of gray-brown, medium quartz sand with 

 some shell material. This upper unit is massive (structureless) and has 

 a sharp lower contact. Hamblin (1965) showed that many apparently massive 

 or homogeneous sandstones* are actually very finely laminated, and it seems 

 likely that under closer scrutiny (e.g., radiographic studies) many of 

 the sands described as massive would show some structure. The next lower 

 unit is a 3-centimeter-thick dark-gray sand silt. From 0.45 to 2.0 meters 

 down in the core, gray and gray-brown, fine to medium, massive, quartz 

 sand is dominant. Mollusk fragments and shells are common near the top 

 and silt lamina are present throughout the unit. There is a sharp con- 

 tact between this unit and the next lower one, a 18.2-centimeter (0.6 

 foot) dark-gray, laminated and interbedded silt, and very fine sand. 

 Contact is sharp with the lowest unit, an admixture of clays, silt sands, 

 and gravels. As noted earlier, the gravels and sands are deeply iron- 

 stained and contain a high percentage of rock fragments . The brown and 

 red clays are tough, cohesive, and interbedded at irregular spacing and 

 thickness with the sandy gravels. No fauna are present. This unit is 

 typical of fluvial (point bar) deposits. Kraft (1971) and Sheridan, Dill, 

 and Kraft (1974) noted that the common presence of Pleistocene fluvial 

 gravels in the shallow subsurface of the Delaware inner shelf and this 

 sample probably represents a similar or related deposit. 



Core 42, collected in the central part of the study area from a region 

 of subdued topography (location shown in Fig. 23), displays several typi- 

 cal sediment relationships (Fig. 30). The upper 2 feet is typical gray- 

 brown, medium-sized surface sands and contains shell fragments of Spisula 

 solidis si-ma. A gradational change exists at about 2 feet, to a gray, fine 

 to medium, quartz sand with numerous white shell fragments. Between 2.2 

 and 3.9 meters (7.3 and 12.9 feet) is a complex sediment unit consisting 



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