Learn about coastal landforms including the different types of coastal erosion and deposition and the landforms they create.
This lesson includes:
one video introducing the different types of coastal erosion and the landforms that they create
a slideshow demonstrating stump formation
one video explaining how a 'spit' is formed
two activities to build on the knowledge
Watch this animated clip to find out about the different types of coastal erosion such as hydraulic pressure, abrasion and attrition, and the landforms that they create, eg headlands and caves.
Coastal landforms created by erosion
The coastline is constantly eroding. There are four key types of erosion:
- Abrasion - waves transport material which hit the cliff and gradually wear it away.
- Hydraulic action - as waves approach the coast they trap air and force it into gaps in the cliff. Eventually this weakens the rock.
- Attrition - waves cause the rocks to crash against each other, breaking them down into smaller and rounder pieces.
- Corrosion (also known as solution) - salts and acids in seawater dissolve the rock gradually over thousands of years.
In addition, changes in landforms can be a result of wind erosion, weathering and sub-aerial processes (processes located at the Earth's surface) such as mass movement (a large scale downward movement of rocks and material).
Headlands and bays
A headland is a high area of land that extends out into the sea.
Headlands are usually formed of more resistant (able to withstand change) rock types than bays (a low-lying inlet of land on the coast).
If there are different bands of rock along a coastline, the weaker or softer rock, such as clay, is eroded fastest. This leaves more resistant rock types, such as granite, sticking out.
Caves, arches, stacks and stumps
Headlands can be vulnerable to erosion because they stand out from the rest of the coast. Over time, other features may develop on a headland:
Cliff erosion and wave-cut platforms
Stages in cliff retreat
- Waves attack the bottom of the cliff, particularly during storms and at high tide.
- Eventually a wave-cut notch (an area of erosion at the base of a cliff formed by the waves) is formed.
- At the same time weathering attacks and weakens the top of the cliff.
- The weakened cliff is left unsupported and eventually collapses.
- Once the sea has removed the fallen rocks it can start the process again.
- The cliff will move back and leave a rocky platform at the base called a wave-cut platform (a flat area in front of a cliff, just below the low tide mark. These were formed when the waves eroded the cliff, but left a flat platform behind).
Coastal landforms created by deposition
Deposition occurs when the sea has less energy, eg in sheltered bays (a coastal area that is protected from strong winds and large waves). Material that has been eroded from the coast is transported by the sea and later put down.
Longshore drift (the movement of material along a coastline due to the angled approach of waves) is a process of transportation that shifts eroded material along the coastline.
- Waves approach the coast at an angle.
- Swash carries sediment up the beach at an angle.
- Backwash carries sediment down the beach with gravity – at right angles to the beach.
- This creates a zig-zag movement of sediment along the beach.
Spits are also caused by deposition - they are features that are formed by the process of longshore drift.
A spit is an extended stretch of beach material that only joins the mainland at one end. They start to form where there is a change in the direction of the coastline.
An example of a spit is Spurn Head, north of the Humber Estuary in the north east of England. It is fed by the movement of material from the erosion of the Holderness Coast to the north. This is an area of weak boulder clay.
Salt marshes may be formed behind a spit. The zone behind a spit becomes a sheltered area. Water movement slows down and so more material is deposited. Deposition may form a salt marsh.
Beaches are formed from deposits of sediment.
Watch this short film with Katie Knapman discussing a ‘spit’ as a coastal feature before visiting Spurn Head to look at how shifting sands have a significant impact.
Here are a few activities to help you remember what you've learned about coastal landforms.
Formation of a spit activities
Download the worksheet to complete the following activities to test your knowledge of spit formation.
Use the diagram and the word bank in the worksheet to label the satellite image. Use a ruler and pencil to add labels in the correct places to the photograph.
Use the words provided to fill in the gaps.
This resource is from Teachit
There's more to learn
Have a look at these other resources around the BBC and the web.