Detailed near-bottom geophysical profile across the continental slope off northern California

A geophysical profile was run across the continental slope off the California-Oregon border by use of a deeply submerged instrument package, approximately 50 m above the sea floor, containing a proton magnetometer and a 3.5-kHz transducer for shallow seismic penetration. Surface-towed seismic reflection equipment was operated concurrently. The deep-tow data show that the slope is relatively smooth; this agrees with interpretation of surface seismic profiles. Features smaller than 1 km in length can be resolved with the deep profiles but not with the surface profiles. The deep profiles show smallscale undulations less than 0.5 km long that are especially well formed on the steeper parts of the slope. These undulations may be caused by minor downslope movement of surface sediment or by depositional processes. The deep-tow and surface seismic profiles can be combined to give a more accurate structural picture of the continental slope than can be obtained with surface data alone.