Two major current projects are focusing on processes and rates of marine sediment transport on the inner shelf, at the shelf edge, and on the continental slope. They are the Inner Shelf Sediment Transport Experiment (INSTEP) and the Marine Geotechnical Rational Use of the Sea Floor (RUSEF).

INSTEP is designed to investigate the rates and directions of sediment transport and the process by which sediments are resuspended from the bottom. Initial studies are on the inner Long Island, New York, shelf, a typical barrier-island coast. Suspended-sediment flux, bottom erosion versus deposition, and bottom characterization are integrated work units. The nucleus of the project is data collected from three "state of the art," bottom-boundary-layer sensing platforms which measure (1) suspended-sediment concentration and current 1 m off the bottom; (2) current-velocity and sediment-concentration profiles in the bottom 1 m of the water column, and (3) the current-velocity profile in the bottom 2 m and the suspended-sediment concentration 1 m above the bottom. The study is designed to measure, for the first time, the threshold of sediment transport with increasing current in the marine environment owing to the combination of unidirectional and wave-generated currents.

Marine Geotechnical RUSEF programs include seafloor-stability studies on the continental slope off the northeastern United States and on the shelf off the Mississippi delta, and a sediment-transport study along the northeastern United States shelf edge. Most of the northeastern continental slope north of Cape Hatteras has been mapped with shallow-penetration seismic reflection profiling and narrow-beam echo soundings. Extensive piston and hydroplastic gravity coring was done in both regional and site-specific areas. For the first time, several large slump blocks have been identified, one of which has been mapped in detail. A major effort is underway to identify by geotechnical methods the conditions (processes and mechanisms) leading to mass slumping and other types of seafloor instab lities.

The Mississippi delta research is a cooperative NOAA-Lehigh University seafloor-engineering study using in-situ instrumentation to determine and assess critical soil properties important in stability analyses.

Two other studies of interest to the petroleum industry are a geochemical study of hydrocarbon concentrations in the water column and in bottom sediments, and an extensive current-meter program, both in the New York Bight from the shelf edge to the inner shelf.

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