Holocene Evolution and Distribution of Large Structural Estuaries

Sediment deposition with coastal systems is determined by the interaction between hydrodynamic processes and morphology. For Barrier Estuaries, the development of a confining sediment barrier at the mouth developed after the Holocene Marine Transgression (HMT) introduced wave processes to a coastline. However in some estuaries, such as San Francisco Bay, the morphological features which restrict the mouth developed before the HMT and are comprised of resistant bedrock, which responds relatively slowly to changes in hydrodynamic conditions. These types of structurally defined estuaries have been identified regionally. Recently a global review of the distribution and abundance of Large Structural Estuaries (LSEs) has been conducted, and LSEs were identified across the worlds coastlines. Several of the LSEs identified appear to have reached an equilibrium, where sediment is no longer being deposited, and they remain dominated by intertidal mud flats. Unfortunately, the sediment deposition within these systems during the Holocene not well understood. In this presentation I will review the key findings of the global review, interpret patterns of Holocene infill in a South East Australian LSE, and discuss the possible influences of the Holocene evolution of LSEs on their distribution and abundance.