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Shallow subsurface strata consist of gently dipping Neogene sedimentary 

 beds that conform to the gradient and direction of the Atlantic Coastal Plain 

 and display no evidence of tectonic deformation. Eleven major acoustic sur- 

 faces, including the presumed Tertiary-Quaternary nonconformity at about -30.5 

 to -61 meters (-100 to -200 feet), are present within the upper 122 meters 

 (400 feet) of the shelf subbottom. Buried channels are common to the sea 

 floor of the entire region; in the Delaware Bay entrance, most channels are 

 cut to 46 meters (150 feet) below sea level and are filled laterally from both 

 the New Jersey and Delaware shelves. Many small channels on the Maryland shelf 

 are alined with existing onshore drainage or historical inlet sites. 



The upper 6 meters (20 feet) of the inner shelf consists of terrigenous 

 sands and silts derived from the adjacent Coastal Plain and Piedmont Province. 

 Environments of deposition represented on the shallow shelf are: modern marine, 

 back barrier, lagoonal, and fluvial. Gray-brown, fine to coarse, well-sorted 

 quartz sand is the dominant lithology on the surface and decreases in relative 

 abundance with depth. The shoal sands unconformably overlie poorly sorted fine 

 sands and muds remnant from Holocene back-barrier and lagoonal deposition, which 

 are periodically exposed and eroded on the sea floor. 



Linear shoals are a dominant topographic feature of the U.S. mid-Atlantic 

 shelf and off the Maryland shelf. They have a high potential as an offshore 

 source of sand for use in beach restoration. Individual shoals typically con- 

 tain between 15 and 54 million cubic meters (20 and 70 million yards) of fine 

 to coarse, well sorted to moderately sorted quartz sand. Total estimated vol- 

 ume of suitable material is about 1.7 x 10 9 cubic meters (2.2 x 10 9 cubic yards). 



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