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The AAPG/Datapages Combined Publications Database

Journal of Sedimentary Research (SEPM)

Abstract


Journal of Sedimentary Petrology
Vol. 43 (1973)No. 2. (June), Pages 371-380

New Jersey Continental Shelf Near Bottom Current Meter Records and Recent Sediment Activity

Charles E. McClennen

ABSTRACT

Modern sedimentary processes associated with the ridge and depression topography of the New Jersey continental shelf were investigated with the aid of near bottom current meter measurements and also estimates of near bottom wave orbital velocities derived from classical wave theory and available surface wave observations. Four current meters were set 1.5 to 2.0 m above sea bottom in 30, 59, 74, and 143 m depths for nine to eleven days during the late springs of 1970 and 1971. The root mean square speeds of the meter records were 13.7, 11.8, 12.9, and 19.5 cm/sec. in order of increasing depth, with a maximum recorded 2.5 minute average speed of nearly 40 cm/sec. and a net southwesterly transport. Both current and wave data indicate reworking of the surface sand cover on the shelf. In d termining the relative importance of wave vs. current activity the true value of the critical erosion velocity is of primary importance. The present day physical reworking of the surface sediments is indicated independently by bottom photographs of ripples and by sedimentary structures in box cores, with reworking being generally limited to the upper meter of sediment. No mechanism for the present formation of the larger scale ridge and depression topography is indicated by the currents measured or the wave considerations.


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