ABYSSAL CURRENTS AND ADVECTION OF RESUSPENDED SEDIMENT ALONG THE NORTHEASTERN BERMUDA RISE

An integrated study using current meters, time-series nephelometers, a nd water samplers for measurements of particulate matter concentration revealed an intense nepheloid layer centered on the slopes of the Eas tward Scarp-the northeastern boundary of the Bermuda Rise. These slope s also contained extensive furrows, truncated seismic reflectors, and Wisconsin-age and older surface sediments. The abyssal circulation in this region appears to be accelerated when it encounters the steep top ography of the Eastward Scarp, eroding sediments, creating the erosion al furrows, and moving eroded sediment upslope. Instruments on top of the Bermuda Rise recorded episodic events (''benthic storms'') where p article concentrations at 25 m above the bottom increased from a backg round level of 60 mug l-1 to a maximum of 251 mug l-1 and current velo cities were nearly 20 cm s-1. Net transport of both water and entraine d sediment was to the west-northwest. During the largest benthic storm water temperature decreased by 0.1-degrees-C, consistent with a 300-6 00 m upslope transport of water and resuspended sediments from the upp er slopes of the Eastward Scarp. When currents carry resuspended sedim ent over the rim of the Eastward Scarp to the plateau region, the curr ent slows, depositing its sediment load. Thus the plateau is growing u pwards slowly at the expense of the surrounding scarps.