Cross-bedded tidal megaripples from king sound (Northwestern Australia)

Abstract

Migration of megaripples and sand waves in shallow seas and estuaries suggests a possible model for the formation of widespread marine cross-bedding. Most examples have been studied only externally, many of them from echo-sound ing; their internal structure is unknown, but cross-bedding has been assumed. Megaripples in King Sound are exposed at low tide and their internal structure has been examined. Many are cross-bedded with steeply dipping foresets. Facing of the foresets indicates that they may be developed by either the flood or ebb tide. The current direction implied by external morphology appears to be a reliable guide to that indicated by the cross-bedding.