Shear strength measurements carried out on the 0–20 cm interval of continental slope and continental rise surficial sediments yielded mean values per station that ranged from 3.7 to 8.9 kPa. The factors controlling the bathymetric variation of sediment shear strength appear to be sediment texture (which is controlled locally by sediment spillover) on the upper slope, increased deposition of fines (silt- and clay-sized particles) from suspension and greater bioturbation activity on the middle slope, and bottom current sediment reworking on the base-of-slope and upper rise.Sediments deposited on the downslope side of the present presumed location of the Western Boundary Undercurrent (WBU) axis have comparatively high shear strength gradients that appear to denote the increased proportion of fine sediment deposition during early to middle Holocene time when the WBU axis may have been located further upslope than at present.

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