Weathering
The processes by which rock is broken into smaller pieces by the action of the weather. There are different types of weathering, there is freeze thaw weathering, biological weathering and chemical weathering.
Freeze-thaw weathering
Freeze-thaw weathering occurs when rocks are porous (contain holes) or permeable (allow water to pass through).
Biological weathering
Plants and animals can also have an effect on rocks. Roots burrow down, weakening the structure of the rock until it breaks away.
Chemical weathering
Rainwater and seawater can be a weak acid. If a coastline is made up of rocks such as limestone or chalk, over time they can become dissolved by the acid in the water.
Erosion
Erosion is the wearing away of rock along the coastline. Destructive waves are responsible for erosion on the coastline. There are four types of erosion:
- Hydraulic action - this is the sheer power of the waves as they smash against the cliff. Air becomes trapped in the cracks in the rock and causes the rock to break apart.
- Abrasion - this is when pebbles grind along a rock platform, much like sandpaper. Over time the rock becomes smooth.
- Attrition - this is when rocks that the sea is carrying knock against each other. They break apart to become smaller and more rounded.
- Solution - this is when sea water dissolves certain types of rocks. In the UK, chalk and limestone cliffs are prone to this type of erosion.
Deposition
When the sea loses energy, it drops the material it has been carrying. This is known as deposition. Deposition can occur on coastlines that have constructive waves.
Factors leading to deposition include:
- waves starting to slow down and lose energy
- shallow water
- sheltered areas, eg bays
- little or no wind
Have a great day <3