Rivers revision 2

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FROST SHATTERING
Physical ( freeze thaw ) - this happens when rainwater enters cracks or gaps in the rock and then freezes if temperatures drop below zero.
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CHEMICAL WEATHERING
Chemical ( acid rain ) - all rain is slightly acidic. If the air is polluted by factories and vehicles, it can become more acidic. When rain falls on rocks, the acid in it can react with weak minerals, causing them to dissolve and the rock to decay.
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BIOLOGICAL WEATHERING
The action of plants or animals on the land. Seeds may fall into cracks in the rocks and may grow when moisture is present. The roots force their way into cracks causing the rocks to be broken up.
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SOIL CREEP
This is the slowest downhill movement of soil. Gravity will pull the water that is contained in the soil down the slope. The soil will move downhill with the water. Can move very slowly and we often cannot see it but it may move faster after rainfall
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SLUMPING
Common on river banks. Large areas of river bank may move through rotational slipping. Common on clay river banks. The clay dries out and cracks. When it rains the soil becomes lubricated. The clay may then slip along this weakened slip plane.
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FLOOD DEFENCES
To stop floods, defences may be built to protect homes and businesses. An example of this is channelisation. This is where the banks of the river are strengthene
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Other cards in this set

Card 2

Front

Chemical ( acid rain ) - all rain is slightly acidic. If the air is polluted by factories and vehicles, it can become more acidic. When rain falls on rocks, the acid in it can react with weak minerals, causing them to dissolve and the rock to decay.

Back

CHEMICAL WEATHERING

Card 3

Front

The action of plants or animals on the land. Seeds may fall into cracks in the rocks and may grow when moisture is present. The roots force their way into cracks causing the rocks to be broken up.

Back

Preview of the back of card 3

Card 4

Front

This is the slowest downhill movement of soil. Gravity will pull the water that is contained in the soil down the slope. The soil will move downhill with the water. Can move very slowly and we often cannot see it but it may move faster after rainfall

Back

Preview of the back of card 4

Card 5

Front

Common on river banks. Large areas of river bank may move through rotational slipping. Common on clay river banks. The clay dries out and cracks. When it rains the soil becomes lubricated. The clay may then slip along this weakened slip plane.

Back

Preview of the back of card 5
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