1. 2.4 How do coastal
processes shape the
land?
Part B

2. What landforms are created by coastal processes?
A Erosional landforms
Blow-hole
Sea arch
Geo
Stack
Sea cliff
Sea cave
Wave-cut platform

3. What landforms are created by coastal processes?
B Depositional landforms
Beach
Spit
Bar
Tombolo

4. Is wave action the only factor in shaping the coast?
No, there are several factors interacting with each other to create coastal landforms.

5. Subject to active wave erosion Uplifting (or lowering) of land
Is wave action the only factor in shaping the coast?
1 Tectonic movement
Subject to active wave erosion
Tectonic movement can cause land to rise or fall.
The uplifting or lowering of the coastline changes the zone of active wave erosion.
Sea
Uplifting (or lowering) of land
Plate
Compressional
force

6. Is wave action the only factor in shaping the coast?
2 Nature of rocks
Horizontal bedding plane
Wave undercutting enlarges the notch and causes collapse of rock above the notch. Parallel retreat of cliffs is resulted.
Land
Sea
Notch

7. Is wave action the only factor in shaping the coast?
2 Nature of rocks
Bedding plane dipping seawards
Rocks loosened by wave erosion and mass movement slide down along the bedding plane.
Sea
Land

8. The slope is more resistant to wave erosion.
Is wave action the only factor in shaping the coast?
2 Nature of rocks
Bedding plane dipping landwards
The slope is more resistant to wave erosion.
Sea
Land

9. Is wave action the only factor in shaping the coast?
3 Weather and climate
Global warming leads to a rise in sea levels because of the thermal expansion of water and melting of polar ice caps.
Changes in sea levels are changing the position of the zone of active wave erosion.

10. Is wave action the only factor in shaping the coast?
3 Weather and climate
A warmer world would generate more storm surges, thereby affecting coastal landforms.

11. Is wave action the only factor in shaping the coast?
4 Fluvial processes
Rivers bring sediment to the coast as they flow to the sea.
Delta
Deposition occurs at the coast where wave action is weak. Sediment may gradually build up to form depositional landform such as a delta.
River Nile
Red Sea
The River Nile, Africa
(Credit: NASA)

12. Is wave action the only factor in shaping the coast?
5 Marine organisms
Some marine organisms protect the coast from wave erosion and favour deposition.
Mangroves
For example, coral reefs and mangroves.

13. What landforms are created by coastal processes?
A Erosional landforms
Sea cliffs and wave-cut platforms
Undercutting continues and the notch is enlarged. The overhanging part above the notch collapses. It forms a sea cliff.
A notch is formed by undercutting.
Waves repeatedly pound against the coast.
The waves erode the part of the coast between high tide and low tide.

14. What landforms are created by coastal processes?
A Erosional landforms
Sea cliffs and wave-cut platforms
Over time, a gently sloping or flat surface called a wave-cut platform is developed at the base of the sea cliff.
Erosion continues, the sea cliff retreats inland.

15. What landforms are created by coastal processes?
A Erosional landforms
Sea cliffs and wave-cut platforms
Sea cliff
Wave-cut platform
Ping Chau in Mirs Bay

16. What landforms are created by coastal processes?
A Erosional landforms
Sea caves and geos
Block diagram
Cross-section
Sea
Land
High tide level
Low tide level
Line of weakness
Geo
Sea cave
Collapse of
cave roof
Sea cave
When waves splash against the roof of a narrow sea cave, the roof may collapse. A geo is formed.
A line of weakness in the cliff is exposed to waves.
Active wave erosion widens the line of weakness to form a sea cave.

17. What landforms are created by coastal processes?
A Erosional landforms
Sea caves and geos
A sea cave in Sai Kung
A geo in Sai Kung

18. What landforms are created by coastal processes?
A Erosional landforms
Sea arches and stacks
This leaves a mass of rock with steep sides standing offshore. This is the stack.
Further erosion may cause the sea arch to collapse.
When a sea cave gets eroded from time to time, it might cut through to form a sea arch.

19. What landforms are created by coastal processes?
A Erosional landforms
Sea arches and stacks
A sea arch and a stack in Canada
(Credit: Getty Images)

20. What landforms are created by coastal processes?
A Erosional landforms
Blow-holes
A vertical or near vertical tunnel is formed along the vertical weakness as a blow-hole.
When waves break into the sea cave, hydraulic action of waves takes place along the vertical weakness in it.
A sea cave is developed along a horizontal line of weakness. w

21. What landforms are created by coastal processes?
A Erosional landforms
Blow-holes
Halona Blow-hole in Hawaii
(Credit: Getty Images)
During storms, waves breaking into the sea cave may force water or just air out of the blow-hole.

22. What landforms are created by coastal processes?
B Depositional landforms
Beaches
Wave energy is dispersed in sheltered bays. Deposition takes place to form beaches.
Sand and shingle are built up between the lowest and the highest water levels.

23. What landforms are created by coastal processes?
B Depositional landforms
Beaches
Waikiki Beach, Hawaii

24. Materials are built up to form a spit
What landforms are created by coastal processes?
B Depositional landforms
Spits
The sediment accumulates and builds up into a spit, with one end attached to the land, and the other end extending out to the sea.
Materials are transported along the coast by longshore drift.
Wind direction
Change of coastline
Land
Marshland
Longshore drift
Longshore drift
Materials are built up to form a spit
Where the coastline changes, the materials are deposited in slack water.
Area behind the spit is of low energy, mud and marshland begins to develop
Spit extends
Sea
The spit extends as sediment continues to accumulate.
Wave crest
Longshore drift

25. End of the spit is bent or recurved
What landforms are created by coastal processes?
B Depositional landforms
Spits
A Spit in Greece
As the waves are refracted, the end of the spit becomes hooked.
Land
Marshland
Longshore drift
spit
Sea
Longshore drift
End of the spit is bent or recurved
Wave crest
(Credit: Corbis)

26. What landforms are created by coastal processes?
B Depositional landforms
Bars
When a spit develops and extends across a bay, a bar is formed.
A lagoon is formed behind the bar.

27. What landforms are created by coastal processes?
B Depositional landforms
Bars
Chesil Beach in England is formed from a bar
(Credit: Corbis)

28. What landforms are created by coastal processes?
B Depositional landforms
Tombolos
When the spit builds up and joins an island to the mainland or two islands together, a tombolo is formed.

29. What landforms are created by coastal processes?
B Depositional landforms
Tombolos
The Cheung Chau tombolo is formed when two spits join together.