1. Coastal Processes

2. Starter: What is meant by the Coastal Zone?
Write your own detailed definition of what you think is meant by the ‘Coastal Zone’. You should be able to include at least three sentences within your definition.

3. Look at the following pictures carefully
Look at the following pictures carefully. Can you think of anything else to add to your description of the coastal zone?

4. Learning Objectives To know and understand the main features of waves
To know and understand what is meant by fetch
To know and understand the different types of erosion
Learn and use new vocabulary.

5. Why are waves generally larger in the south west than in the south east?
Wave energy depends on the fetch, the strength of the wind and the length of time over which the wind has blown.
fetch = the distance over which the wind has blown
Look at an atlas or a wall map to find out the largest fetch around the British Isles.

6. Why do waves break? wavelength
the bottom of the wave touches the sand, slows down and the top of the wave topples over

7. Swash and backwash Backwash Swash
Note: Backwash is always at right angles to the beach

8. Destructive Waves Main features
They are high in proportion to their length
The backwash is much stronger than the swash so that rocks, pebbles and sand are carried back out to sea
They are frequent waves, breaking at an average rate of between eleven and fifteen per minute
Would a smaller or greater fetch create these types of wave?
Are these types of waves likely to form erosional or depositional coastal features?

9. Processes of erosion Corrosion Hydraulic action Processes of erosion
Abrasion
Attrition

10. Cut up the key words and statements and match correctly
Cut up the key words and statements and match correctly. Check your answers with the following slide.

11. Attrition
Material carried by the waves bump into each other and so are smoothed and broken down into smaller particles.
Hydraulic action
This process involves the force of water against the coast. The waves enter cracks (faults) in the coastline and compress the air within the crack. When the wave retreats, the air in the crack expands quickly causing a minor explosion. This process is repeated continuously.
Corrosion
This is the chemical action of sea water. The acids in the salt water slowly dissolve rocks on the coast. Limestone and chalk are particularly prone to this process.
Abrasion/Corrasion
This is the process by which the coast is worn down by material carried by the waves. Waves throw these particles against the rock, sometimes at high velocity.

12. Key questions 1. Explain why so much erosion takes place during storms
2. Why will a storm cause more erosion along some parts of the coastline than others?

13. Dorset coastline

14. Constructive waves Main features
They are long in relation to their height
They break gently on the beach so that the swash carrying materials up the beach is stronger than the backwash carrying them away
They break gently, with only six and nine waves per minute

15. Plenary Homework task – learn key words and definitions for: Fetch
Crest
Swash
Backwash
Constructive wave
Destructive wave