Chapter 15 Sediment Waves and Bedforms

Abstract

Large-scale sediment waves are some of the most distinctive and frequently described depositional features generated by bottom currents, and cover huge areas of sea floor. This chapter outlines the morphology, genesis, identification, and depositional environment of both fine- and coarse-grained sediment waves formed by bottom currents. It also describes and illustrates some of the related large-scale features generated by bottom currents, such as––sand ribbons and erosional furrows. The application of data obtained from sediment waves and features related to bottom-current reconstruction are also investigated. Bottom-current sediment waves are geographically widespread and focus on case studies from the North-West UK continental margin. Fine-grained sediment waves generated by bottom currents are generally found draping the flanks and crests of sediment drifts. Coarse-grained sediment waves generated by bottom currents are relatively common in shelf environments, but in deep water they are scarcer than their fine-grained counterparts. Large-scale erosional scours may be tens of metres deep and several kilometers across, and are only found in areas of topographic constriction where bottom currents are strongly focused. Bottom-current velocities associated with various types of bedforms observed in the deep ocean are tabulated.