Summary Information for Field Activity 1992-016-FA

Area of Operations: Deep Water Dump Site DWDS 106, Continental Rise offshore New Jersey, New York, United States, North America, North Atlantic

Dates: July 20, 1992 to July 29, 1992

Chief scientist: Jim Robb

Objectives: Sidescan sonar imaging of the ocean bottom around the DWDS-106 Municipal Sludge dumpsite, for support of DSRV ALVIN dives and to characterize sea-floor microtopography.

Type of Activity:

Information to be derived:

Summary: AMS-120 sidescan unit with the Qmips processing system functioned very well, with only 4 hours lost when a wire termination failed apparently due to tow strumming. Site surveys were accomplished at 4 off-dumpsite sites, and two areas within the dumpsite study area were imaged and mosaicked while at sea. The data commonly show features indicating offshore-directed bottom flows. A control site (2600 m at 70 deg 40 min W) and 2 sampling sites SW of the main study area show a smooth ocean bottom, with minor flow indications, such as elongated moats or dune structures. Within the study area, in contrast, our 8-line mosaic shows striking offshore lineations, evidently erosional furrows (parts were observed last year using Jason), as well as smooth bottom where a tongue of muddy sediments overlies the furrowed surface. The furrows lie downslope from where canyons debouch. Also mosaicked with three lines was a rough area of greater relief and high backscatter that may be part of a large olistostrome (landslide block).

Contact: Jim Robb (jrobb@usgs.gov)

InfoBank: uses the identifier O-51-92-NJ. Visit this site for more information.

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