Earth Sciences 1022A/B Lecture Notes - Lecture 19: Longshore Drift
25 Nov 2015
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Document Summary
Earth sciences 1022a lecture 19 shorelines. A surface waveform of energy moves through the water whose molecules move side to side and up and down. As a wave approaches the shore it feels bottom and breaks into surf that moves up a beach as swash then water flows back down as backwash. Storm waves erode headlands by wave impact compressing air in fractures, by abrasion, undercutting. Waves bend as they approach an irregular shoreline (wave refraction) so that erosion focuses on headlands, deposition occurs in bays. Most waves hit the shore at an angle and move sediment along beaches by the zig-zag pattern of swash and backwash called beach drift. Oblique waves in the surf zone produce longshore currents that flow parallel to the shore: move most of the sediment in transport that is supplied mainly by rivers. Erosional include, depending on geology and wave activity: wave-cut cliffs:
