Megaripple

A megaripple is a large current-formed bedform produced by strong tidal or unidirectional flow, intermediate in scale between small current ripples and sandwaves, with spacing from under a meter to several meters. The Ashley (1990) SEPM classification retired the term, recommending small to medium dune instead, because subaqueous flow-transverse bedforms form a size continuum, spacing under 1 m to over 1,000 m, rather than discrete classes. Megaripples migrate with the dominant flow and are reworked over the spring-neap cycle. They roughen the bed, raising bottom stress and bed roughness, which matters for sediment-transport and acoustic-backscatter seabed classification in surveys.