Sediments from the continental slope and shelf edge in the northwest Gulf of Mexico were tested to determine their strength, stability, and consolidation characteristics. Consolidation tests for Sabine River delta samples and abyssal-plain samples were used in the interpretation of the shelf and slope samples. To approximate in situ conditions, a direct shear-test machine was used to measure shear strength, and an Anteus Back Pressure Consolidometer was used to determine consolidation.

The topography of this area has been attributed to local slumping of unconsolidated and unstable marine sediments. Although the Sabine River delta samples were underconsolidated, the continental-shelf and slope samples all were overconsolidated. The overconsolidation of these samples and the high values of shear strength are assumed to be the results of low deposition rates and incipient cementation of the mineral grains. Analysis of the void ratio versus log pressure consolidation curves indicated that the sediments were "sensitive" and, therefore, relatively undisturbed by the sampling process.

The shear strength ranged from 0.05 TSF for the upper 1 m. of sediment to more than 0.5 TSF for a simulated depth of 20 m. The shear-strength tests indicate that the slope sediments should be stable to great thicknesses on even higher slopes than exist in this area.

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