Bottom currents, nepheloid layers and sedimentary features under the Gulf Stream near Cape Hatteras

Abstract

The velocities of near-bottom currents were measured at six locations on a 180-km transect of the Gulf Stream adjacent to Cape Hatteras. The average velocities indicate a southwesterly flow - the Western Boundary Undercurrent. Maximum recorded velocities at each of the six locations ranged from 15 to 47 cm/sec. Depth distributions of suspended particulate matter over the transect indicated that near-bottom nepheloid layers were present and that relatively large amounts of suspended matter were being carried to the southwest. Bottom photographs taken over the same transect, however, showed no evidence that the sediment surface was being affected by the active bottom currents. These results indicate that swift bottom currents do not always leave a record of their work on deep ocean sediment.