weathering of rocks

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Where do the rocks come from?
We get many useful substances from rocks, such as
building materials, metals, pigments and jewels.
But where do we get the rocks themselves from?
They come from the Earths crust. The Earths
crust is the thin outer layer of the Earth. It is
about 30 km thick on land and only about 8 km
thick under the sea.
crust
mantle
inner core
outer core
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Types of weathering
There are three types of weathering

• physical weathering
• biological weathering
• chemical weathering.

Which type of weathering is caused by each of
these

• temperature change
• acid rain
• plants and animals?

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Physical weathering
Physical weathering occurs when rock is broken
down into smaller pieces by the effects of
temperature and water.

• Exfoliation weathering (or onion-skin
  weathering) is caused by very hot weather.
• Freeze-thaw weathering is caused by the melting
  and freezing of water.

Exfoliation and freeze-thaw weathering tend to
occur in very different types of landscapes.
Which type of weathering do you think will
primarily occur in the desert, and which will
occur in the mountains?
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Exfoliation weathering in action
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Freeze-thaw weathering in action
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Plants and weathering in action
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Erosion
As a rock is weathered, pieces of it fall off.
This is called erosion. They will then be
transported away by water, wind or glaciers.
by water
by wind
by glacier