What has created these landscapes?. South Coast of England

What has created these landscapes?

South Coast of England

Rocky Desert Sinai Peninsula

Free State – South Africa

Cape Point South Africa

South Africa

Sandstorm in the Sinai Desert

Kalahari Desert

Weathering

All landscapes are affected by the forces of weathering. These are:

Physical WeatheringBiological Weathering, andChemical WeatheringWeathering is the breaking down of rocks

without movement, and is therefore different to erosion where movement of rocks takes place

Physical WeatheringThe breaking down of

rocks by heat or cold – freeze thaw or onion skin weathering

Biological Weathering

This involves the breaking down of rocks through acids released by plants such as lichens, but can also cause physical problems through tree roots or burrowing animals.

Chemical Weathering

This occurs when water has a chemical reaction with the minerals in the rocks – this is particularly true of rocks that contain calcium carbonate such as limestone and chalk.

Marine Erosion Processes

Remember the processes of erosion covered in the Rivers module?

What were they?CLUE: HAAC

BBC Bitesize video

HAAC

Corrosion

Hydraulic Action

The force of waves hitting a cliff (or sea wall) compresses water and air into cracks and joints. This can be equivalent to 30,000kg per square metre.

This increase in pressure may lead to cracks widening and pieces of rock breaking off.

Corrasion / Abrasion• Rock fragments may be

picked up by waves and thrown against the rock face of cliffs by subsequent waves.

• The effectiveness of the corrasion depends on the strength of the wave, the nature of its ‘load’ and the resistance of the rock in the cliff face.

• Corrasion is most effective at the base of cliffs

Attrition• Rock fragments which

have become detached by hydraulic action and corrasion are worn down into smaller and more rounded pieces.

• Currents and tidal movements cause the fragments to be swirled around and to grind against each other.

• This type of erosion produces pebble beaches.

Corrosion• Salts and acids in sea

water can react with rocks , slowly dissolving them away.

• The photo shows this process on a cliff of Portland limestone which has been chemically attacked by carbonic acid and other chemicals in sea water.

Coastal Kung Fu

What movements could you create to show the 4 processes of marine erosion (remember plate tectonics and Kung Fu Panda?)

With a partner devise a way to show the processes.

Work time

• OCR B Text- page 33- read and write ‘The impact of geology on coastal landforms’.

• Answer Question 4- ‘Using the Dorset coast as an example, explain how geology can affect the rates of erosion and weathering.’

• Extension: Can you think of ways that human activity may increase the rate of coastal erosion?

Plenary

Weathering or erosion – you decide!