Swash

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The distance a wave has travelled.

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Fetch, wind speed and wind duration.

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Destructive waves

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Waves are caused by the transfer of energy from the wind to the sea due to the friction of the wind on the water’s surface.

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Coastal erosion is the wearing away of the land by the sea.

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Abrasion occurs as breaking waves, concentrated between the high and low watermarks, which contain sand and larger fragments wear away the base of a cliff or headland. It is commonly known as the sandpaper effect. This process is particularly common in high-energy storm conditions.

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Attrition is when waves cause rocks and pebbles to bump into each other and break up.

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Corrasion, abrasion, hydraulic action, attrition and corrosion/solution.

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Waves hitting the base of a cliff causes leads to air compression in cracks, joints and folds in bedding planes, causing repeated changes in air pressure. As air rushes out of the crack when the wave retreats, it leads to an explosive effect as pressure is released. This process is supported further by the weakening effect of weathering. The material breaks off cliffs, sometimes in huge chunks. This process is known as hydraulic action.

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When rainwater hits rock it decomposes it or eats it away. This is known as carbonation. This occurs when slightly acidic (carbonic) rain or seawater comes into contact with sedimentary rock, such as limestone or chalk, it causes it to dissolve. A chemical reaction occurs between the acidic water and the calcium carbonate and forms calcium bicarbonate. This is soluble and is carried away in solution. Carbonation weathering occurs in warm, wet conditions.

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Recently weathered rock can be seen at the foot of chalk and limestone cliffs and is easily identified because it is angular.

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Freeze-thaw weathering occurs when rocks are porous (contain holes) or permeable (allow water to pass through). Water enters the rock and freezes. The ice expands by around 9%. This causes pressure on the rock until it cracks. Repeated freeze-thaw can cause the rock to break up.

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Weathering is the breakdown of rock in situ by the action of rainwater, extremes of temperature, and biological activity.

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Salt weathering is when salt spray from the sea gets into a crack in a rock. It may evaporate and crystallise, putting pressure on the surrounding rock and weakening the structure.

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Traction – large pebbles and boulders are rolled along the seafloor.

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Wave energy reduces leading to material being deposited.

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Solution, suspension, saltation and traction.

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Littoral drift

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Any three from:

• Waves enter an area of shallow water/waves enter a sheltered area, eg a cove or bay
• There is little wind
• A river or estuary flows into the sea reducing wave energy
• There is a good supply of material and the amount of material being transported is greater than the wave energy can transport.

Find out more about coastal deposition.