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Under Pressure Coastal Stack & Stump: Sediment Are Thrown Against Weathering (Freeze- the Cliffs by Waves

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Under Pressure Coastal Stack & Stump: Sediment Are Thrown Against Weathering (Freeze- the Cliffs by Waves Tides: UP1 –Waves & Tides Constructive Waves: Longshore Drift: Transportation: • These are the rise and fall of the sea level, due • Traction: mainly to the pull of the moon • Strong swash and weak backwash that • Waves approach the beach at an angle due Large boulders and sediments • As the moon travels around the Earth, it push sand and pebbles up the beach to the prevailing wind direction are rolled along the sea bed. attracts the sea and pulls it upwards. The sun • Low waves with longer gaps between the • As the wave breaks, the swash carries They are too heavy to be helps too – but its much further away. So its crests (6-8 per min – low frequency) material up the beach at the same angle pull is not as strong. • Under 1m (oblique angle) as the prevailing wind picked up fully by the waves. • High tide occurs about every 12 and ½ hours, • Known as spilling waves as they ‘spill’ up • The backwash carries material back down with low tides in between. The difference the beach the beach at a right angle (90o) due to • Saltation: between the high and low tide is called the tidal • Gently sloping wave front gravity where small pieces of shingle range • Formed by storms often 100s KMs away • This means that material is moved along the or large sand grains are • Gentle beach beach in a zig zag route bounced along the sea bed. Waves: Destructive Waves: • Suspension: • Are formed by wind that blows over the sea, friction with the surface of water causes • Weak swash and strong backwash pulling small particles such as silts ripples to form and these develop into waves. sand and pebbles back down and clays are suspended in the • The size of the wave depends on how strong the • Steep high waves where the crest is flow of the water. wind is, how far it has travelled and how long closer together (up to 15 per min – high the wind blows for (fetch), and the speed of frequency) • Solution: the wind (strong winds = stronger waves) • Known as plunging waves as they break when minerals in rocks like • As the water becomes shallower the circular they plunge downwards chalk and limestone are motion becomes more elliptical, this causes the • Steep beach dissolved in sea water and crest of the wave to rise up and collapse on the • Formed by local storms close to the beach, the water rushes up the beach (swash) coast, they can destroy the beach then carried in solution. The and then flows back towards the sea (backwash) • Over 1m UP2 – Transportation load is not visible. Erosion: Weathering: The formation of a • Abrasion – loose rocks and • Mechanical Under Pressure coastal stack & stump: sediment are thrown against weathering (freeze- the cliffs by waves. thaw weathering): ‘Sandpapering’ effect of When it gets cold, water • Cracks in the side of pebbles grinding over a rocky gets into cracks in the a headland are platform often causing it to rock, and it freezes. The enlarged by erosion become smooth water expands when it (Hydraulic action, • Hydraulic action – water is turns to ice, so it puts Mechanical abrasion etc.) forced into cracks in the rock. pressure on the rock, creating a Cave. This compresses air inside. causing it to break up. • The cave eventually When the wave retreats the • Biological is eroded through compressed air blasts out. It weathering: the headland to can force the rock apart, Plants grow in cracks in form an Arch. called cavitation the rock and their roots The formation of headlands and bays: • Over time the arch • Attrition – loose sediment push the rocks apart. Headlands and Bays form on Coastlines where is eroded from the knocked off the cliff by Animals burrow and there are differing bands of hard (resistant) base and weathered hydraulic action and abrasion break up rocks. rock and soft (weak) rock. The weak rocks like from the top until is swirled around. It • Chemical clay erodes faster than the resistant rocks like its roof collapses constantly collides with other weathering: Biological limestone. This leaves the resistant rocks sediment. Rain is slightly acidic, so leaving behind a • Corrosion –sea water dissolves when it comes into jutting out as headlands. The Weaker softer Stack detached calcium carbonate from the contact with rocks, it rocks develop as bays and often accumulate from the headland. rock, such as limestone and wears away the top layer beaches as sediments are deposited in their • The stack will chalk of rock sheltered areas as constructive waves deposit eventually collapse leaving a Stump. UP2 –Erosion and Weathering Chemical material. UP3 & 4 – Coastal Landforms The Impacts of Coastal Erosion: Method How does it work? Advantages Disadvantages The Holderness coast is the fastest eroding coastline in Europe Hard engineering – man made structures to control the erosion 1. Strong prevailing winds creating longshore drift that moves material Recurved Sea wall Made of stone or Total protection from Very expensive. Just like south along the coastline. concrete it reflects erosion and can help a cliff face it will erode 2. The cliffs are made of a soft boulder waves and withstands prevent flooding too. and need replacement clay. It will therefore erode quickly, waves breaking on it and repair especially when saturated as water weakens the clay increasing slipping and slumping speeding up erosion. 3. Land is being lost on an average of 2-3m Groynes A low wall built out into Traps beach material Costly to build and per year along this coastline. the sea that traps sand and creates a protective maintain (still cheaper that is moved by beach, which acts as a than a seawall) and may longshore drift. Usually natural barrier to be viewed as made out of wooden erosion and which is also unattractive. fences but can also be attractive to tourists. Can create problems made out of large ‘down-drift’ as in the boulders such as at case of Mappleton and Mappleton. Sue Earl’s farm UP5 & 6 – Impacts of Erosion Rock armour (rip rap) Large boulders which Absorbs wave energy Still relatively expensive protect the coast by and cheaper than a and again will erode and Sea level rise is a threat to many coastal communities. Sea levels are rising and are predicted to rise further due to breaking up the waves, seawall. need maintenance. global climate change: dissipating the energy of • The melting of ice pack particularly in the Arctic and Antarctic. the waves. • Thermal expansion of the oceans (heating of the Ocean causing expansion) UP7, 8 & 9 – Coastal Management The Maldives: Soft engineering – more sustainable methods that work with natural processes This is a group of around a thousand Beach nourishment Adding sand to the Creates a natural Requires constant low-lying islands to the south west of beach to make it wider. defence, relatively maintenance and India in the Indian Ocean. Their low- This can be brought inexpensive and beach is replacement each year, lying landscape is particularly from elsewhere or attractive to tourists vulnerable to sea level rise caused by dredged from the sea global warming. bed. The islanders are concerned that Dune Regeneration Obstacles are put on the Creates a natural Have to be maintained rising sea levels will inundate (flood) and can be destroyed in UP5, 8 & 9 – Sea Level Rise beach for sand dunes to barrier against erosion their islands as well as increase the form around. Marram and a new habitat for stormy weather. Blocks access to the severity of erosion. This will cause Managing sea level rise in the Maldives: grass is planted to bind wildlife. beach for tourists. problems such the sand together. Loss of Tourist industry • Building dykes to hold back sea water. Protecting the islands from Loss of Fishing industry flooding and allowing tourism to continue for now. Managed retreat Abandoning the existing Low cost & encourages People will still lose their Houses and land lost • Build the islands upwards, sea defences and the creation of beaches property and may need Fresh water supplies • Educate world leaders on the impacts of climate change and populations building new ones and salt marshes which compensation contaminated at risk. further inland, creating are good for the Climate refugees (forced a salt marsh which also environment • Build sea walls in densely populated areas floods in storm migration as a result of climate • Begin to abandon the islands slowly, becoming environmental refugees. conditions. change). • Ask for foreign aid to build defences and offer advice. .
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