Abstract Debris flows tend to conserve their density, whereas turbidity currents constantly change theirs through erosion, deposition, and entrainment. Numerical models illustrate how this distinction leads to fundamental differences in the behaviors of debris flows and turbidity currents and the deposits they produce. The models predict that when begun on a slope that extends onto a basin floor, a debris flow will form a deposit that begins near its point of origin and gradually thickens basinward, ending abruptly at its head. By contrast, deposition from an ignitive turbidity current (i.e., one that causes significant erosion) will largely be restricted to the basin floor and will be separated from its origin on the slope by a zone of erosion. Furthermore, the turbidite will be thickest just beyond the slope base and thin basinward. These contrasting styles of deposition are accentuated when debris flows and turbidites are stacked.

Abstract The first test of the Bell Aerospace gravity Gradiometry Survey System (GSS) for geologic applications was conducted in April 1994 in collaboration with the U.S. Navy. The GSS is a recently declassified gravity sensing system that contains the world's only moving-base gravity gradiometer. The system measures both gravitational acceleration and gravity gradients, yielding six measurements that define the local gravity field and its gradients in three dimensions a technologic advance in measuring gravity analogous to the advance from 2-D to 3-D seismic profiling through the towing of multiple rather than single hydrophone arrays. The gravity gradiometry test survey was conducted over a buried salt structure southsoutheast of New Orleans in water depths of ˜1500 m. The quality of the survey data is excellent. In declassified grids of the data at 2-km wavelengths, gravity gradients are resolved to 0.5 and gravity to 0.07 mGal. Simple models are used to illustrate the power of this data in subsurface structure definition. The potential utility of gravity gradiometry in oil and gas exploration then is demonstrated through application of the survey data in improving a geologic model of a part of the survey area derived from 3-D seismic data.