The Role of Wave Erosion on Sloping and Horizontal Shore Platforms in Macro- and Mesotidal Environments
The Role of Wave Erosion on Sloping and Horizontal Shore Platforms in Macro- and Mesotidal Environments
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宏观和中潮汐环境中波浪侵蚀对倾斜和水平海岸平台的作用
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
Jacob I. Kanyaya
中科院分区：
文献类型：
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作者：
A. Trenhaile;Jacob I. Kanyaya
摘要在芬迪大潮汐湾（大潮差13. 5 m）的Scots湾的倾斜玄武岩海岸平台和魁北克加斯佩的Mont Louis（大潮差3 m）的水平泥质岩平台上，测量了潮汐周期内的波浪。摄像机被用来记录波浪的高度和周期，这些波浪与一系列分级的金属杆相对，这些金属杆沿着被测量的海岸正常剖面锚定。现场测量和理论的考虑表明，波高增加与海拔在苏格兰湾，反映了一个轻轻倾斜的潮坪以下的中潮水平和更高的梯度上比平台的下部的发生。岩石内产生的压力计算沿着关节和其他不连续性表明，波条件是适合在苏格兰湾的机械波侵蚀。波浪通常在圣路易斯山平台向海边缘的低潮悬崖上破碎，防止任何波浪作用于后面的浅水淹没平台表面。在大潮期间，更大的水深允许相当大的波浪穿过平台，但海滩通常保护悬崖脚，除了一些直立的山脊外，在这个高度的水面上没有岩石暴露在波浪作用下。水平的Mont Louis平台主要受风化作用的向下磨损，但如果没有保护性的海滩，在涨潮时波浪仍会袭击悬崖，这表明平台可能在高潮水位附近被波浪切割，随后因风化作用降低到目前的高度。
Abstract Waves were measured over tidal cycles on a sloping, basaltic shore platform at Scots Bay in the macrotidal Bay of Fundy (large tidal range 13.5 m), and on a horizontal, argillite platform at Mont Louis in Gaspé, Québec (large tidal range 3 m). Video cameras were used to record the height and period of the waves against a series of graduated metal poles anchored along surveyed, shore-normal profiles. Field measurement and theoretical considerations suggest that wave height increases with elevation at Scots Bay, reflecting the occurrence of a gently sloping tidal flat below the midtidal level and higher gradients on the upper than on the lower parts of the platform. Calculated pressures generated within the rock along joints and other discontinuities suggest that wave conditions are suitable for mechanical-wave erosion at Scots Bay. Waves generally break on the low tide cliff at the seaward edge of the platform at Mont Louis, preventing any wave action on the shallow, flooded platform surface behind. During high spring tides, greater water depths allow fairly large waves to cross the platform, but a beach generally protects the cliff foot and, apart from a few upstanding ridges, there is no rock exposed to wave action at the water surface at this elevation. Downwearing by weathering dominates on the horizontal Mont Louis platform, but waves would still attack the cliff during high tides if there were no protective beach, which suggests that the platform may have been cut by waves near the high tidal level and subsequently lowered by weathering to its present elevation.