What is a coast?
The coast is a narrow strip zone where the land and the sea overlap and directly interact. It is affected by many processes and represents the most varied and rapidly changing of all landforms and ecosystems.
Coastal Processes
Waves
There are two different types of wave:
There are two different types of wave:
- Constructive waves
- Destructive waves
These video clips show the main features of each wave type.
Activity
Watch the two clips and identify the characteristics of constructive and destructive waves.
Activity
Watch the two clips and identify the characteristics of constructive and destructive waves.
- Which type of wave do you think is the most dangerous?
- Which type of wave will make the beach get bigger?
- Which type of wave will erode the beach?
Constructive waves
|
Destructive waves
|
Landforms created by erosion
Erosion creates amazing coastal landforms.
Watch these clips to find out about the formation of headlands, wave cut notches, wave cut platforms, caves, arches, stacks and stumps.
Erosion creates amazing coastal landforms.
Watch these clips to find out about the formation of headlands, wave cut notches, wave cut platforms, caves, arches, stacks and stumps.
|
Your task is to create a script to explain what is occurring in the following animation.
|
|
Homework
Create a detailed annotated diagram to explain how coastal landforms are created. |
|
The pictures above show Durdle Door.
On the left, is Durdle Door in 2015, you can see the large arch. On the right is Durdle Door in the future, the arch has collapsed leaving a stump. No one knows when this future might arrive, it could be this year, or even in 100 years, but there is no doubt that this will happen.
On the left, is Durdle Door in 2015, you can see the large arch. On the right is Durdle Door in the future, the arch has collapsed leaving a stump. No one knows when this future might arrive, it could be this year, or even in 100 years, but there is no doubt that this will happen.
What effects the rate of erosion?
Erosion can sometimes occur very quickly, but in other locations even tiny changes can take hundreds of years.
Watch the two clips below and try to write a list of things that can effect the rate of erosion.
Erosion can sometimes occur very quickly, but in other locations even tiny changes can take hundreds of years.
Watch the two clips below and try to write a list of things that can effect the rate of erosion.
|
|
Landforms created by deposition
Key question: What happens to sediment after it has been eroded?
When the sea loses energy, it drops the sand, rock particles and pebbles it has been carrying. This is called deposition. Deposition happens when the swash is stronger than the backwash and is associated with constructive waves.
Deposition is likely to occur when:
Key question: What happens to sediment after it has been eroded?
When the sea loses energy, it drops the sand, rock particles and pebbles it has been carrying. This is called deposition. Deposition happens when the swash is stronger than the backwash and is associated with constructive waves.
Deposition is likely to occur when:
- waves enter an area of shallow water.
- waves enter a sheltered area, eg a cove or bay.
- there is little wind.
- there is a good supply of material
This is Loe Bar in Cornwall.
Legend has it, that this bar was created by the Giant Tregeagle. One day, Tregeagle was marching across Cornwall. As he walked over the river, the stones that he always kept in his pocket fell from a hole and blocked the river forever.
By learning about deposition, we can suggest a more likely explanation!
Legend has it, that this bar was created by the Giant Tregeagle. One day, Tregeagle was marching across Cornwall. As he walked over the river, the stones that he always kept in his pocket fell from a hole and blocked the river forever.
By learning about deposition, we can suggest a more likely explanation!
Key Words
Erosion: The breaking down of the land by the force of the waves.
Transportation: The sea carries and moves the sediment.
Deposition: The sea looses energy and drops the sediment that it is carrying.
After rock has been eroded, it is transported by the sea and can then be deposited somewhere else along the coastline.
Watch the following video clips to find out what Long Shore Drift is.
Erosion: The breaking down of the land by the force of the waves.
Transportation: The sea carries and moves the sediment.
Deposition: The sea looses energy and drops the sediment that it is carrying.
After rock has been eroded, it is transported by the sea and can then be deposited somewhere else along the coastline.
Watch the following video clips to find out what Long Shore Drift is.
- Longshore drift is the method by which sediment is transported along a coastline
- When waves approach the coastline at an angle the sediment will be carried up the beach (swash) at the same angle; it then moves back down (backwash) at right angles.
- The result is a zig zag motion along the beach which moves sediment along a coastline.
Now we know how sediment can move along a coast, we can work out how depositional features are formed.
The Holderness Coast
The Holderness Coast
- Material is eroded from the coastline around Mappleton and Hornsea.
- The eroded material is transported south by long shore drift.
- When the material reaches the mouth of the River Humber, the energy of the sea decreases and the sediment is deposited. This forms the spit.
- Over many years, the spit continues to grow.
Homework: Use google maps to create an annotated sketch map of Spurn Head Spit.
Your sketch map must include:
|
|
How can humans protect the coast?
Some people think that the natural coastal processes of erosion and deposition should be controlled so that the shape of the coast does not change and the land behind the coast is protected. As climate change increases the amount of extreme weather and causes sea levels to rise, the worlds coastline is at particularly high risk. Some of the worlds most densely populated cities are in vulnerable coastal zones; therefore coastal defence is crucial.
There are many different ways of protecting the coast, including hard and soft defences.
Hard defence: Durable, long term structures. Often made of rock, wood or concrete.
Soft defence: Sustainable defences that need maintenance. Often made out of sand, marram grass or soil.
Some people think that the natural coastal processes of erosion and deposition should be controlled so that the shape of the coast does not change and the land behind the coast is protected. As climate change increases the amount of extreme weather and causes sea levels to rise, the worlds coastline is at particularly high risk. Some of the worlds most densely populated cities are in vulnerable coastal zones; therefore coastal defence is crucial.
There are many different ways of protecting the coast, including hard and soft defences.
Hard defence: Durable, long term structures. Often made of rock, wood or concrete.
Soft defence: Sustainable defences that need maintenance. Often made out of sand, marram grass or soil.