Submarine canyons of Santa Monica Bay, Southern California: Variability in morphology and sedimentary processes

The Redondo Canyon and channel system presents a number of morphologies, namely terraces, gullies, arcuate scarps, distinctive canyon-floor scarps (DCFS), crescent-shaped bedforms (CSBs) and scours. Their geneses, especially the CSBs along the Redondo axial channel, are the result of the morphodynamic interaction between turbidity flows and the seafloor. We infer that sediment gravity flows are the dominant process shaping the Redondo Canyon and channel system and transporting material to the San Pedro Basin. In contrast, the Santa Monica Canyon displays a smooth, flat-bottomed and partially in-filled axial channel, which lacks axial incision and large sediment bedforms indicating infilling at present. We interpret the large scours on the flanks of Santa Monica Canyon and the sediment waves on the Redondo Fan, respectively, as bedforms produced by repeated cyclic steps in turbidity currents which alternated between net erosional and net depositional.