On the Delmarva inner shelf, the main topographic features are those 

 shown in Table 2--the shoreface, linear-shoal field, shoal-retreat massif, 

 and shelf -transverse valley. Characteristics of these features are de- 

 scribed below. 



a. Shoreface . The term shoreface has been defined by at least three, 

 and perhaps more, criteria, most of which are impractical to use because 

 they rely on information that is difficult or impossible to obtain from 

 profile or map data. For example, one definition explains shoreface as 

 "the narrow zone seaward in terms of the area where sands and gravels 

 actively oscillate with changing wave conditions" (American Geological 

 Institute, 1962; Allen, 1972). 



The preferred definition for this study is the one used by Meisburger 

 and Field (1975) to refer to the relatively steep slope descending from 

 the low water line or inshore terrace to a break in slope at the level of 

 the shelf ramp. Using this definition, the limits of the shoreface slope 

 and width of the seaward margin of the shoreface are readily determined 

 from either map or profile data (Fig. 5, A). Perturbations or irregular- 

 ities in the surface configuration of the shoreface are of two types-- 

 erosional and constructional. An erosional effect occurs when a stratum 

 of different lithology, cementation, or other characteristic, which makes 

 it more resistant than the super or subjacent material, is exposed in the 

 shoreface of a retrograding shoreline. Constructional elements on the 

 Delmarva shoreface are the large shoals that interrupt the usually smooth 

 shoreface (Fig. 5,B). 



b. Linear-Shoal Field . Linear-shoal field refers to inner shelf 

 areas containing groups of linear shoals with the same orientation and 



of similar scale in relief and length. Well -developed linear-shoal fields 

 have been mapped by Duane, et al . (1972) in the vicinity of Fort Pierce, 

 Florida; False Cape, Virginia; Ocean City, Maryland; and central New 

 Jersey. The shoals are oriented at a small acute angle (~20°) to the 

 shoreline and are comprised of clean medium sand. A schemetized plan 

 view of a linear-shoal field is shown in Figure 5,B. Note that innermost 

 shoals are connected to, or are part of, the shoreface and are called 

 shoreface shoals. Those farther offshore are termed isolated shoals. 

 Duane, et al . (1972) interpreted these features as Holocene features that 

 formed in the submarine environment and were consequently stranded as sea 

 level rose and the shore retreated. 



Shoals are large bodies of unconsolidated, medium to coarse, moder- 

 ately well sorted sand which overlie planar mud layers. There is 

 sufficient evidence (e.g., historical surveys, limited current metering, 

 polished grains several feet below shoal surface, etc.) that transport 

 and deposition of sediments in the vicinity of the linear shoals is an 

 active process and the shoals are not "relict" or inactive features. 

 Because of the economic significance of these linear shoals and because 

 of their importance to the evolution of the shelf surface they will be 

 discussed more extensively in later sections. 



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