GEOL 3070 Lecture Notes - Lecture 18: Longshore Drift, Wave Power, Basalt
20 Mar 2017
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Document Summary
Large storm surf generates ~25,000 kg/m2 of pressure. Repeated application & release of pressure fractures rocks. Wave refraction tends to focus wave energy and erosion on headlands, resulting in shore stra. Beaches (sediments) cover ~30% of the us shoreline. Sediments carried onshore by wave swash and offshore by wave backwash. High energy mobilizes sediments and carries them away from the shore (gravity) Beach sediment size depends on transport offshore and therefore on: Slope: low=fine, steep = coarse (sed. backwash >> swash) Despite refraction, waves still often hit shore at a slight angle. Onshore movement is in the direction of the wave (swash) Net transport of water and sediment is parallel to shore. Longshore water also moves away from shore in narrow jets. Occur in deeper channels where wave energy is reduced. Longshore trough: part of beach below water where longshore current is moving. Scarp: part of beach that is being directly impacted by wave action.
