Destructive waves

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Constructive wave

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A wave is a disturbance on the surface of the sea or ocean, in the form of a moving ridge or swell.

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Swash

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Backwash

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Corrasion is when destructive waves pick up beach material (e.g. pebbles) and hurl them at the base of a cliff. Over time this can loosen cliff material forming a wave-cut notch.

Find out more about coastal erosion.

Corrosion/solution is when certain types of cliff erode as a result of weak acids in the sea.

Find out more about the processes of coastal erosion.

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.

Find out more about coastal erosion.

The wearing away of land by the sea.

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

Find out more about the processes of coastal erosion.

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

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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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Chemical weathering is the breakdown of rock through changing its chemical composition.

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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.

Solution, suspension, saltation and traction.

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Littoral drift

Find out more about longshore drift.

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

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Material is dissolved and carried by the water.

Find out more about coastal transportation.