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2 of 8 © Boardworks Ltd 2013
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 Earth’s crust. The Earth’s 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
3 of 8 © Boardworks Ltd 2013
Types of weathering
Which type of weathering is caused by each of these:
temperature change
acid rain
plants and animals?
There are three types of weathering:
physical weathering
biological weathering
chemical weathering.
4 of 8 © Boardworks Ltd 2013
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?