Beach and sea-cliff dynamics as a driver of long-term rocky coastline evolution and stability
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Rocky coastlines, with wave-battered headlands interspersed with calm sandy beaches, stir imaginations and aesthetic sensibilities the way few other landscapes do. Despite their prevalence (sea cliffs or bluffs are present along nearly 75% of the world’s oceanic coastlines), we know very little about how rocky coastlines evolve. Quantitative studies of large-scale (>1 km) rocky coastline evolution are just beginning, and this work asks several unresolved and fundamental questions. For example, what determines the planform morphology of a rocky coastline? Can it reach an equilibrium configuration and cross-shore amplitude? What rocky coastline processes and characteristics scale the formation time and size of sea stacks? The overarching theme of the following four chapters is the dynamics between beaches and sea-cliffs. Sea-cliff erosion and retreat is a primary source of beach sediment on rocky coastlines. As cliffs contribute sediment to the beach, it is distributed by alongshore sediment transport, and the beach can control future rates of sea-cliff retreat in two main ways: in small amounts, sediment can accelerate cliff retreat by acting as an abrasive tool, and in larger amounts, the beach acts as a protective cover by dissipating wave energy seaward of the sea-cliff. These feedbacks have been observed on rocky coastlines and in laboratory experiments, but have not been explored in terms of their control on large-scale and long-term (i.e., millennia) rocky coastline evolution. The aim of this dissertation is to explore the range of ways that beach and sea-cliff dynamics can drive rocky coastline evolution with simple analytical and numerical models, and to generate testable predictions.
Limber, Patrick Wayland (2012). Beach and sea-cliff dynamics as a driver of long-term rocky coastline evolution and stability. Dissertation, Duke University. Retrieved from https://hdl.handle.net/10161/6107.
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