A LEVEL GEOGRAPHY COASTS

WAVE CREST This is the top of the wave as water in a wave rises causes crest WAVE TROUGH As water in a wave falls WAVE HEIGHT Distance between the wave crest and trough WAVE PERIOD Time between waves WAVE FREQUENCY Number of waves that break on a beach in a given period of time WAVE STEEPNESS WAVE HEIGHT/WAVE LENGTH cannot exceed 1:7(this is the point at which the wave breaks) WAVE ENERGY In deep water the energy of a wave is proportional to the wave length X by the wave height(squared).This means that even small increase in wave length can produce a large increase in wave energy. WAVE ENERGY IS DIRECTLY RELATED TO WAVE HEIGHT THE ENERGY OF IS RELEASED WHEN IT BREAKS SWASH The body of foaming water that rushes up the beach when the wave breaks.It obtains its energy from the energy released by the breaking wave BACKWASH The water which returns down the beach after a wave has broken ABANDON THE LINE The strategic withdrawal of human occupation in areas of high risk.Use of less expensive and sustainable methods to "abandon the line" of the coast. often unpopular with farmers and property owners i.e. national trust policy Studland bay ABRASION The wearing away of the shoreline by sediment carried by waves.Also erosion by friction scraping, scouring and rubbing of load in contact with banks and bed. ACCRETION The accumulation of marine sediments.Where deposition exceeds erosion. ADVANCE THE LINE This involves active intervention to produce a defence line that is seaward in some way of existing line. This would usually involve some form of reclamation, the construction of offshore breakwater or similar. ARCH Differential erosion of adjacent caves opening in the middle i.e. durdle door. Last 50 to 100 years. ATTRITION Particles are reduced in size and rounded off by colliding with one another as they are washed in the waves, erosion grinds down the cliff fall material BAR Coarse grained deposit of sediment extending across the mouth of the bay sometimes reaching the other side and sealing off the entrance BERM Low hill of sand or gravel that forms at the upper limit of the swash.They are short term features and are removed by successive tides and storms. ATTRITION Particles are reduced in size and rounded off by colliding with one another as they are washed in the waves.Erosion grinds down the cliff-fall ent of water back towards the sea after a wave has broken. BEACH NOURISHMENT Sand and shingle brought from elsewhere are added to beaches to maintain their breadth and depth to protect from erosion in a natural way i.e. hengistbury. BLOW-HOLE A chimney or pipe leading from a cave up through cliff to the surface.Caused by erosion and often exploitation of joints in the geology.