Coasts

Question	Answer
Fetch	The distance a wave has traveled.
Swash	Water running up the beach.
Backwash	Water running back down the beach.
Consructive wave	A wave with a powerful swash and a weak backwash.
Destructive wave	A wave with a weak swash and a powerful backwash.
Hydraulic action	Air may become trapped in joints and cracks on a cliff face. When a wave breaks, the trapped air is compressed which weakens the cliff and causes erosion.
Abrasion	Bits of rock and sand in waves grind down cliff surfaces like sandpaper.
Attrition	Waves smash rocks and pebbles on the shore into each other, and they break and become smoother.
Solution	Acids contained in sea water will dissolve some types of rock such as chalk or limestone.
Longshore Drift (LSD)	The movement of material along a beach in a zig-zag pattern.
Solution	Minerals are dissolved in sea water and carried in solution. The load is not visible. Load can come from cliffs made from chalk or limestone, and calcium carbonate is carried along in solution.
Suspension	Small particles are carried in water, e.g. silts and clays, which can make the water look cloudy. Currents pick up large amounts of sediment in suspension during a storm, when strong winds generate high energy waves.
Saltation	Load is bounced along the sea bed, eg small pieces of shingle or large sand grains. Currents cannot keep the larger and heavier sediment afloat for long periods.
Traction	Pebbles and larger sediment are rolled along the sea bed.
Arch	A wave-eroded passage through a small headland. This begins as a cave formed in the headland, which is gradually widened and deepened until it cuts through.
Bar	Where a spit grows, due to long shore drift, across a bay. A bar can eventually enclose the bay to create a lagoon.
Biological Weathering	The breakdown of rocks through the action of plants and animals.
Managed Retreat	Allowing cliff erosion to occur as nature taking its course: erosion in some areas, deposition in others. Benefits include less money spent and the creation of natural environments.
Mass Movement	The downhill movement of weathered material under the force of gravity. The speed can vary considerably, from soil creep, where the movement is barely noticeable, to slumps, slides and mudflows, where the movement becomes increasingly more rapid.
Wave Cut Notch	An undercut part of a cliff base where wave attack concentrates erosion.
Physical Weathering	The disintegration of rock into smaller pieces without any chemical change in the rock. It is most likely in areas of bare rock where there is no vegetation to protect the rock from extremes of weather e.g. freeze-thaw and exfoliation (onion weathering).
Revevetments	Wooden, steel, or concrete fence-like structures that let sea water and sediment to pass through, but absorb wave energy. A beach can build up behind the revetment and provide further protection for the cliff.
Spit (E.g. Spern Head)	A long, narrow accumulation of sand and shingle formed by longshore drift and deposited where the coastline abruptly changes direction. One end is connected to the land and the other end projects out to the sea, often with a hooked end.

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	Created by Becca Westwell about 9 years ago