SPATIOTEMPORAL CONTROLS ON CUSPATE FORELANDS: IMPORTANCE OF WIND-DRIVEN CURRENTS

The origin of cuspate forelands has been debated for well over a century but no theory has emerged that fully explains both the origin and processes controlling the size and time necessary for development. Understanding the scalability and linkages of physical and sedimentary processes around cuspate forelands is critical to predicting regional-scale concerns such as the export of pollutants and nutrients across-shelf and beach sediment budgets. An archival survey of passive margin, micro-tidal shorelines from the US and select locations around the world reveal cuspate forelands only develop in regions in which the predominant wind direction is shore-parallel. Observations from large cuspate forelands in the Mid-Atlantic Bight further show that wind-driven currents play a substantial role in directing net sediment transport seaward from the promontories, which may accelerate growth and influence the overall size and shape of the adjacent foreland shoreline. These findings and earlier modeling work related to high-angle waves support the hypothesis that the origin of cuspate forelands and constraints on size and development time are primarily controlled by wind direction and resulting feedback between waves, currents, and promontory-shoal bathymetry.