Coastal ridge plains represent a valuable record of past shoreline deposition. However, there remain questions regarding shoreline behavior on intermediate timescales (sub-centennial), the impact of storms, and process of ridge genesis. We address these questions through high-resolution reconstruction of the sandy-beach progradation at Boydtown Beach in Twofold Bay, southeastern Australia, over the past 1000 years using ground-penetrating radar (GPR) and optically stimulated luminescence (OSL) dating. GPR profiles are dominated by seaward-dipping reflections that result from beach and dune progradation. Prominent reflections with heavy-mineral concentrations are also preserved resulting from storm erosion. OSL ages reveal alternative phases of steady and episodic accretion, rather than a constant progradation. We hypothesize that steady phases may result from moderate storm events where each successive storm only partially erodes the recovery of the previous event. This results in incremental seaward accretion of the active beach. Phases of episodic accretion could be the result of larger storm events or storm clusters when large post-storm recovery rapidly shifts the active shoreline seaward. The two modes of shoreline progradation (steady and episodic) appear broadly associated with a change in ridge-and-swale morphology whereby subdued ridge swale topography is associated with steady or incremental progradation and higher, better-defined ridges with episodic accretion. These results suggest that a single coastal ridge plain experiences variable intermediate-scale shoreline behavior in response to storm events which then lead to multiple modes of ridge genesis.

中文翻译：

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在过去约1000年中，一个渐增的沙质海岸线的亚百年解析行为

沿海山脊平原代表了过去海岸线沉积的宝贵记录。但是，在中间时间尺度（百年以下），海岸线的行为，风暴的影响以及山脊的形成过程仍然存在疑问。我们通过使用地面穿透雷达（GPR）和光激发发光（OSL）测年技术对澳大利亚东南部Twofold湾的博伊德敦海滩的沙滩发展进行高分辨率重建来解决这些问题。GPR剖面主要由海滩和沙丘发育引起的向海倾斜的反射所主导。暴风雨侵蚀也保留了矿物质含量高的突出反射。OSL年龄揭示了稳定和情节性增生的替代阶段，而不是持续增长的阶段。我们假设稳定的阶段可能是由中等风暴事件产生的，其中每次连续的风暴仅部分侵蚀了先前事件的恢复。这导致活动海滩的向海增量增加。暴发后恢复迅速使活跃的海岸线向海移动时，暴发事件或暴发簇的结果可能是突发性增生阶段。海岸线的两种扩展模式（稳定的和渐进的）似乎与山脊和滑坡形态的变化有广泛的联系，其中柔和的脊sw形地形与稳定的或增量的分布以及较高的，轮廓分明的增高的脊有关。