1. Optional Starter: Exam practice: 4 minutes:

2. Exam practise:

3. What made this cliff collapse?
Starter:
Insert above link
What made this cliff collapse?

4. What is weathering?
Weathering is the deterioration (breakdown) of rock, and does not involve the removal of rock as in erosion.
Think of examples of weathering. How do they work?

5. Learning objectives:
To describe and explain the different types of weathering

6. Physical Weathering Freeze-thaw
As this freeze–thaw process is repeated and cracks spread through the rock. Eventually small pieces of rock (called scree) break off altogether.
This is because as water freezes it expands.
This creates powerful forces that can enlarge the cracks.
Most rocks are hard, but despite this they can be broken by just a small amount of water getting into cracks in the rock.
scree

7. Physical Weathering Thermal expansion
In places with large daily changes in temperature (e.g. deserts) expansion and contraction of the rock itself occurs. The surface gets the hottest and so expands the most. This may cause it to “peel off.”

8. Coastal landform development Sub-Aerial processes of weathering
1. What is weathering?
2a. What is physical (mechanical) weathering?
b. In no more that one sentence describe each type of physical weathering.

9. Chemical Weathering Carbonation
There are also acids in the rain that can chemically eat away at rocks – especially rocks consisting of metal carbonates (such as chalk, limestone and marble).
Firstly, there is carbon dioxide gas which dissolves in rain to form weak carbonic acid. This very slowly eats away at certain rocks.

10. What is Biological Weathering?
Tree roots
Tree roots can get into tiny cracks and can physically open them up further.
Organic acids
In addition, decaying plant roots also produce acid which can chemically eat away at the rock.

11. Coastal landform development Sub-Aerial processes of weathering and mass movement
1. What is weathering?
2a. What is physical (mechanical) weathering and when is it most effective?
b. In no more that one sentence describe each type of physical weathering.
3a. What is chemical weathering and when is it most effective?
b. In no more that one sentence describe each type of chemical weathering.
4) What are the two main types of biological weathering?

12. Plenary
Which rock types are most susceptible to weathering?