Weak swash, strong backwash.
Find out more about destructive waves.
The distance a wave has travelled.
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Swash
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Constructive wave
Find out more about constructive waves.
Backwash
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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.
Find out more about coastal erosion.
The wearing away of land by the sea.
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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.
Coastal erosion is the wearing away of the land by the sea.
Find out more about the processes of coastal erosion.
Attrition is when waves cause rocks and pebbles to bump into each other and break up.
Find out more about coastal erosion.
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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Mechanical weathering is the breakdown of rock without changing its chemical structure (composition).
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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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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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Longshore drift happens when waves approach the beach at an angle. The swash (waves moving up the beach) carries material up and along the beach. The backwash (waves moving back down the beach) carries material back down the beach at right angles. This is the result of gravity. This process slowly moves material along the beach and provides a link between erosion and deposition. The material is transported through suspension, traction, solution and saltation. Longshore drift provides a link between erosion, transportation and deposition.
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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.
Longshore drift
Find out more about longshore drift.
Beach material is suspended and carried by the waves.
Find out more about coastal tansportation.
Beach material is bounced along the seafloor.
Find out more about coastal transportation.
