Gently sloping cliffs are formed from unconsolidated material, such as boulder clay, which is a soft rock that erodes quite quickly.
Vertical cliffs are formed from consolidated material, such as sandstone, which is a more resistant rock that erodes slowly.
The collapsed rock debris is removed from the foot of the cliff by the strong backwash of the destructive waves. A gently sloping area of exposed rock called a wave-cut platform is left at the base of the cliff. Composed of more resistant rock and visible at low tide, the wave-cut platform is smoothened by attrition.
SKILLS ACTIVITY
Draw a labelled diagram describing the formation of a cliff and wave-cut platform.
Fig. 9.13(b) Cliffs of Moher, Co. Clare.
Fig. 9.13(c) Cliffs on an OS map: notice the dark black line at the coast, which is a result of contours being placed on top of each other.
EXAM TIP
A relevant labelled diagram (optional) and a named example of the feature will be awarded 1 SRP each.
EXAM LINK (HL) Surface Processes (30 marks)
Examine the impact of the processes of erosion on the formation of one coastal landform that you have studied.
2015, Q1B Marking Scheme:
Named processes = 2 + 2 marks Named landform = 2 marks Examination = 12 SRPs × 2 marks
CHECK YOUR LEARNING
1. Briefly explain how a cave is formed. 2. Describe how a cave can develop into a sea stack. 3. Name one place in Ireland where a blowhole can be found. 4. What is a geo? 5. Explain the role played by compression in cliff formation. 6. What is a wave-cut platform? 7. What does a gently-sloping cliff tell us about the type of rock it is made from? Why does it develop this way?
8. How would you recognise a cliff on an OS map? 132
