. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography 40° 2 5' i. 74°00' 73-55' 73°50' 73°45' 100 METERS Fig. 5. Sidescan sonar records of current lineations on the Long Island coast, collected at three dif- ferent periods. Positioning by Raydist. Current lineation pattern (bands A-F) expands to south during observation period. Apparent change in orientation in last panel is due to ship maneuvering. (From Stubblefield et al. in prep.) eroded surface of the lagoonal deposits as the leading edge of a mar
. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography 40° 2 5' i. 74°00' 73-55' 73°50' 73°45' 100 METERS Fig. 5. Sidescan sonar records of current lineations on the Long Island coast, collected at three dif- ferent periods. Positioning by Raydist. Current lineation pattern (bands A-F) expands to south during observation period. Apparent change in orientation in last panel is due to ship maneuvering. (From Stubblefield et al. in prep.) eroded surface of the lagoonal deposits as the leading edge of a marine sand sheet. Bruun's hypothesis is compatible with the stratigraphic evidence and with our limited knowledge of coastal hydraulics. A more rigorous test requires bathymetric time se- ries to document changes in the coastal pro- file. Limited data of this sort are becoming available. Harris (1954) undertook a study of the Long Branch, New Jersey, dredge spoil dumpsite to determine if dumping was nourishing the beach (Fig. 6). In fact, dur- ing a 4-year period, the shoreface under- went between 5 and 26 cm of erosion, while an irregular pattern of deposition prevailed on the inner shelf floor. A somewhat longer time series has been prepared by Kim and Gardner (Woodward-Clyde Assoc.) during study of proposed sewage outfall routes for the Ocean County, New Jersey, sewerage authority (Fig. 7). Two out of three profiles taken indicate m of erosion over 20 years. The third profile is immediately south of a shoreface-connected sand ridge; here comparable aggradation has occurred as a consequence of southward ridge migration. Growth of ridges—Erosional shoreface retreat on the Atlantic cannot be adequately described by a two-dimensional model such as Fig. 4 because the shoreface appears to be the formative zone for sand ridge topog- raphy as well as for the sand sheet into which it is impressed. Clusters of shoreface- sand ridges occur on the New Jersey coast between Br
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