These are vocab cards for coasts

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  • Created by: Izzie
  • Created on: 10-03-11 13:51

Weathering and Erosion

Physical Weathering: Physical weathering is caused by changes in temperature. In hot weather, rock expands and it contracts in cold weather, causing the rocks to crack. This causes parts of cliffs to fall off.

Chemical Weathering: Mildly acidic rain dissolves chemicals in the rock.

Biological Weathering: Plant root snad animals dislodge rock

Corrasion: Waves pick up rocks and pebbles and throw them against the base of the cliff, wearing it away.

Corrosion: Some types of rock and pebbles react with seawater which dissolves the rock.

Hydraulic Action: Air is forced into cracks by waves which widens the cracks. This is repeated over time.

Attrition: Rocks bang against each other by waves, making them smooth.

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Long Shore Drift: Sand and shingle is moved up the beach in this direction.

Prevailing Winds: The direction of the wind in England.

Swash: Rocks move up the beach in swash (the direction of the preaviling winds)

Backwash: Rocks move down the beach in a straight line because of gravity.

Beach: A beach is a landform horizontal to the sea. It is made of rocks, pebbles, sand and shingle which has been deposited over time.

Sand Dune: A semi-permanent mound of sand deposited by the wind and held together by plant roots. they are common by the sea.

Salt Marsh: Flat land found in sheltered areas and estuaries, inhabited by salt-tolerant plants. It is flooded at high tide.

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Coastal Protection

Cost-benefit Analysis A technique for deciding whether to make a change. The user adds up the value of the benefits and subtracts the costs associated with it. Every time one place is protected, another place is put at risk.

Hard Engineering: Putting in place concrete and steel to try and stop all erosion. This is sometimes called "hold the line" strategy, e.g a seawall. This is expensive and can look very ugly.

Soft Engineering: This is using natural processes to try and slow down erosion. It is cheaper but doesn't work as well or last very long, e.g beach nourishment.

Rock Armour/Rip Rap: This is not too expensive and lasts for 30-50 years. They are rocks placed along the beach. The sea makes the loose boulders bang into each other (attrition) and th e wave uses up all of its energy eroding them, not the coast.

Curved Sea Wall (Concrete): This is an expensive method that lasts for 50-75 years. the wave is forced back on itself and into the sea.

Accropodes: Precast interlocking blocks that absorb the impact of the sea. They are more effective than rock armour as the impact of the waves strengthens their interlocking.

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Costal Protetion (cont'd)

Accropodes: Precast interlocking blocks that absorb the impact of the sea. They are more effective than rock armour as the impact of the waves strengthens their interlocking.

Gabions: This is a cheap method that doesn't last that long. The waves use up all their energy eroding the rocks and the wire frame is needed to hold the rock together. If they get too small, the rocks will fall through the gaps.

Groynes: this is the most expensive method of coastal protection. It lasts a reasonable amount of time. They prevent longshore drift. they trap rocks and the wave uses up all its energy eroding it.

Beach Nourishment/Replenishment: This is a method of soft-engineering that doesn't last long and is moderately expensive. Sand and pebbles are dredged up from the sea and this is quite attractive. it has to be replenished often.

Cliff Stabilisation (regrading/reseeding): This is a method of soft-engineering. regrading is where the gradient of the cliff is changed to a gentler angle. Reseeding is where more vegetation is planted on the cliff. The roots keep the cliff together. there is a lot of human labour involved.

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Features of a Headland

Headland: The coast is made up of hard and soft rocks layers.The soft rock is eroded faster than the hard rock so the hard rock is left sticking out. This is the headland.

Bay: A bay is made up of the eroded soft layers of rock and beaches form in them. They are sheltered.

Spit: A spit is formed by deposition. Sand and shingle is transported to where the seas meets a river. Salt and Fresh water have different densities. They do not mix easily which causes deposition. Overtime, the spit grows but doesn't spread all the way across the river because of fast currents in the middle. A hook is formed because of a less common second wind direction. A spit is really a beach which, instead of following the coastline extends out to sea, often where a coast changes shape.

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Features of a Headland

Cave: Caves are formed by the erosion of cracks and joints and the base of the cliff.

Arch: An arch is formed where a cave erodes through a headland.

Stack: A pillar of rock formed when the top of an arch collapses, due to weathering and the lack of supporting material underneath it.

Stump: The remnant of a stack after it has collapsed, due to continued weathering and erosion. Sometimes a stump will be covered in water at high tide.

Wave-cut Platform: A flat area of rock which is left behind as an overhang above a notch collapses (cliff retreat).

Wave-cut Notch: Waves erode the base of the cliff more quickly than the rest. Eventually, an overhang will collapse.

Blow Hole: The roof of the cave collapses leaving a hole. In storms, seawater spurts out of the hole.

Rock Debris: Rocks that have fallen from the cliff face.

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What is the difference between weathering and eros

Weathering and erosion are both the breakdown of rocks and boulders into scree (smaller stones) and eventually into soil. Weathering can occur anywhere, but for erosion to occur, moving water is needed.

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