1. Complete the crossword to recap what we have learnt so far.

2. Learning objectives To know where Christchurch Bay is.
To understand why the cliffs are collapsing at Christchurch Bay.
To explain the social, economic and environmental impacts of coastal cliff collapse.

3. Why do cliffs collapse?
Cliffs are dangerous places and there are a number of reasons why they can collapse…

4. Marine processes
This when the cliff is eroded by the sea using hydraulic action and abrasion.
Hydraulic action
Abrasion

5. Sub-aerial processes
This happens when the cliffs are weakened by weathering, such as freeze-thaw or solution.
Mechanical
Chemical

6. Size of rocks falling gets smaller
Mass movement (recap)
As marine processes and sub-aerial processes weaken the rock, it causes the cliff to collapse.
Mass movement is when the rocks (usually loosened by weathering) move down under the force of gravity.
ROCKFALL
SLIDING
MUDFLOW
SLUMPING
(rotational slip)
Size of rocks falling gets smaller

7. Mass movement Sliding Slumping
Heavy rainfall
Activity: Read the definitions on page 149 and draw two annotated diagrams to describe these processes.

8. What else contributes to cliff collapse?
Human activity! Constructing roads and buildings along cliff tops adds extra pressure and weight, increasing instability.

9. Case study: Christchurch Bay
Christchurch Bay on England’s South coast has a major problem with cliff collapse...
Use page 150 of your textbook to complete the case study sheet.

14. Plenary 3 causes of cliff collapse at Christchurch Bay
2 coastal towns or resorts affected
1 environmental impact