Coastal Processes Lab
The sea never rests. Learn how waves erode, transport and deposit, and how a headland is worn down to a cave, an arch, a stack and finally a stump.
Use it, the way the marks are given
Free interactive practice at using the material, which is what the marks are for.
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The restless coast
The coast is a battleground between land and sea. Waves erode rock, transport the pieces along the shore, and deposit them elsewhere. Understand these processes and you can explain every coastal landform.
Four ways the sea erodes
Learn the four erosion processes:
Match each erosion process to its meaning
- Hydraulic action
- Abrasion
- Attrition
- Solution
- Air and water forced into cracks break the rock
- Sand and pebbles thrown at the cliff wear it away
- Rocks knock together and become smaller and rounder
- Seawater dissolves soluble rock
Name the process
What is hydraulic action?
- Waves forcing air and water into cracks, breaking the rock
- Rocks grinding into smaller pieces
- Seawater dissolving the rock
- Sand blasting the cliff face
Moving along the coast
Eroded material is transported along the shore. Longshore drift moves sediment in a zig-zag: waves push it up the beach at an angle (swash), then it rolls straight back down (backwash). Material also moves by traction, saltation and suspension.
How a stack forms
A headland is eroded in stages. Put them in order.
- A crack forms in the headland
- The crack widens into a cave
- The cave breaks through to form an arch
- The arch collapses, leaving a stack
- The stack is worn down to a stump
Constructive vs destructive
Two wave types shape the coast. Constructive waves are gentle with a strong swash; they build beaches by depositing material. Destructive waves are powerful with a strong backwash; they erode the coast and drag material away.
Erosion only
Select the TWO processes of coastal erosion.
- Hydraulic action
- Abrasion
- Deposition
- Longshore drift
Match each landform to how it forms
- Headlands and bays
- A cave
- A stack
- A beach
- Softer rock erodes faster than harder rock
- Waves erode a weakness in a headland
- An arch collapses
- Waves deposit sand and pebbles
Coastal-processes frame
Waves erode cliffs by processes such as hydraulic action and _____. Material is carried along the coast by _____ drift. _____ waves build beaches, while destructive waves _____ the coast.
Explain the coast
Apply the processes to what you see at the coast.
- Waves widen a crack in a headland into a hollow. This forms a...
- Gentle waves that deposit sand and build up a beach are...
- Sediment moving in a zig-zag along the beach is caused by...
Zig-zag journey
Longshore drift moves material along the coast because waves...
- Approach at an angle, but the backwash runs straight down
- Always hit the beach straight on
- Dissolve the sand as they go
- Never move any sediment
Explain a stack
Explain how a stack forms from a headland. Describe the stages in the correct order.
- Start with erosion of a crack, then a cave
- Explain how an arch forms and then collapses
- Conclude that a stack (later a stump) is left