Sidescan-Sonar Imagery of the Shoreface and Inner Continental Shelf, Wrightsville Beach, North Carolina

Figure 6

A: Enlarged image of sidescan-sonar imagery showing the meter-wavelength ripples that floor the rippled scour depressions (see Figure 5 for location). Ripples in the fine sand are below the resolution of the sidescan system. Note the sharp contact between coarse and fine sediments. Note also the small package of finer sediments within the rippled scour depression. The crests of the larger ripples can be "seen" through this thin deposit.

B: This diver photo from the same location shows the sharp contact between coarse and fine sediments at the northern boundary of the rippled scour depression. Ripple wavelengths in the rippled scour depression (right side of the photo) are approximately 75-100 cm, with heights about 20-30 cm. The rippled, finer sediments on the left of the photo have wavelengths of 10-20 cm and heights 3-8 cm. Diver observations indicate thatthe contact is sharp, occurring over a few centimeters. Coarseripple crests can be traced under the fine sand for several meters,suggesting that fine material periodically infills the edges of therippled scour depression (see Figure 7 and text for discussion).

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