2 The Study of CoastsCoasts can be studied in several different ways dependent upon their classification:Erosional or depositionalSediment type (clastic: shingle and sand; or muddy)Submergent or emergentTectonic settingProcess-based: wave dominated, tide dominated and wind dominated - the agents of erosion
4 Coastal Processes Coastal Form Wind, Waves, Tide, Currents Weathering, Erosion, & DepositionCoastal FormDynamic over Space& TimeEquilibriumWind, Waves, Tide, CurrentsSediment Movement
5 Cliffs and Shore Platforms The Coastal SystemENERGYWAVESTIDESWINDGEOLOGICAL STRUCTUREMATERIALSDominantLess DominantTerrestrialMarineCoarserFinerCliffs and Shore PlatformsMudflatsCoral ReefsBeachesSand Dunes(Hansom, 1988)
6 The Coastal System Coastal Systems: coastal systems vary primarily in response to wave intensity and tidal currentsbreaking waves (and resultant currents) provide most of the systemic energyseveral additional factors also influence coastal processes and landformsoriginal geology of the coastlinerelative 'erodibility' of regional bedrocksea level variations (global and local tectonic or glacio-eustatic changes)coastal systems typically characterized as erosional or depositionalerosional or depositional nature of any coastline varies with the systemic energy
7 Weathering & Erosion What is? Weathering: Breakdown of rock (Geology) to form sediment in situWeathering is a set of physical, chemical and biological processes that alter the physical and chemical state of rocks and soil at or near the earth's surface. Rock and soil is altered physically by disintegrating and chemically by decomposing. Nearly all weathering involves water, mostly directly: frost shattering, wetting and drying, salt weathering, and all chemical weathering is in solution. That is, weathering is climatically driven and thus the term weathering. Because weather and climate occur at the earth's surface, the intensity of weathering decreases with depth and most of it occur within less than a metre of the surface of soil and rock.Erosion:Transport of weathered material from one location to another...The wearing away of land or the removal of beach and/or dune sediments by wave action, tidal currents, wave currents, drainage, or wind. Erosion includes, but is not limited to, horizontal recession and scour and can be induced or aggravated by human activities.