Distinctive landforms result from different processes.
BBC Bitesize coastal landforms video
BBC Coastal processes and landforms video
Landforms resulting from erosion
Wave-cut platforms and stacks video
Cliffs and wave cut platforms
- Waves most often hit the base of a cliff and therefore most erosion is concentrated there.
- This continued erosion at the base of the cliff causes a wave cut notch to be created which is enlarged as the erosion continues.
- The rock above the notch is left unsupported, becomes unstable and eventually collapses.
- The collapsed material is washed away and a new wave cut notch starts to form.
- Repeated collapsing of the cliff causes the cliff to retreat inland.
- A wave cut platform is the rock platform that’s left behind as the cliffs retreats.
Headlands and bays
- Headlands and bays form on discordant coastlines where the rock type alternates between more resistant and less resistant rock at right angles to the sea.
- Differential erosion occurs as more resistant (harder) rock erodes slower than the less resistant rock.
- As the less resistant rock is eroded away quicker it creates a bay leaving the more resistant rock jutting out into the sea as headlands.
Caves, arches and stacks
- Headlands are usually made of more resistant rocks that have weaknesses like cracks.
- Waves crash into the headlands due to wave refraction and enlarge the cracks mainly by hydraulic action and abrasion.
- Repeated erosion and enlargement of the cracks causes a cave to form.
- Continued erosion deepens the cave until it breaks through the headland forming an arch.
- Erosion continues to wear away the base of the arch and weathering weakens the roof.
- The arch eventually collapses to form a stack – an isolated rock that seperate from the headland
Landforms resulting from deposition
- Beaches are formed by constructive waves depositing matieral which has often been eroded further along the coast and transported by longshore drift.
- Sand beaches are flat and wide – sand particles are small and the weak backwash can move them back down the beach, creating a long, gentle slope.
- Shingle beaches are steep and narrow – shingle particles are large and the weak backwash can’t move them back down the beach. The shingle partciles build up to create a steep slope.
Spits and bars
- Spits from where there is a sharp change in the direction of the coastline e.g. at a river estuary.
- Longshore drift transports material along the coastline and past the bend. Then deposits it in the sea as the waves loose energy in the deeper water.
- This process repeats and the spit gets bigger over time.
- Changes in the direction of the wind can cause the spit to become curved at the end (a hook).
- The spit won’t grow across the whole river estuary due to the river current flowing out into the sea.
- Behind the spit a saltmarsh is created as the area is protected from the waves and plants start to grow there.
A bar is created when a spit grows across a bay joining up two headlands.
Formation of a spit video