Waves Essay

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------------------------------------------------- Top of Form | | | Bottom of Form Waves * Swash: the movement of a wave up onto the beach * Backwash: the movement of a wave returning to the sea * Constructive waves: build up beaches by depositing material * They have a stronger swash than backwash. * Destructive waves: erode the beach as they remove more material than they deposit. * They have a stronger backwash then swash. * Fetch: the distance across the ocean that the wind has been blowing on it Erosion Waves erode the coastline through the processes of: * Hydraulic Action: the force of the waves crashing against the cliffs & weakening faults & widening cracks. * Abrasion: The sand & small material carried in the waves scraping against the rocks/cliffs & wearing them away. * Attrition: Rocks & boulders in the water crash into each other and break into smaller pieces. * Corrosion: The sea water dissolves soluble material in the coastline – especially in limestone & chalk. Longshore Drift * Longshore drift is the movement of material along the coastline. * It occurs due to the swash bringing material up the beach at an angle * The backwash then drags the material backwards into the sea & the process repeats Deposition Spits are ridges of sand extending into the sea. Spits. | Tombolos are spits that join up with an island located close to the coastline. | Bars are ridges of sand that run parallel to the coastline, sealing off bays. | Coastal Management * Wooden groynes can be built along beaches to reduce the effects of longshore drift. They do not stop it but slow it down. * Sea walls can be constructed at the back of beaches to absorb and deflect the waves energy, protecting cliffs or promenades. * Beach nourishment is the practise of bringing in extra sand

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