the earth in space summary. 2 of 42© boardworks ltd 2008 where do the rocks come from? we get many...
TRANSCRIPT
The Earth in The Earth in SpaceSpace
Summary
2 of 42 © Boardworks Ltd 2008
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 47 © Boardworks Ltd 2008
Identifying rocks
4 of 47 © Boardworks Ltd 2008
Different rocks = different uses
5 of 47 © Boardworks Ltd 2008
Forming sedimentary rocks
6 of 47 © Boardworks Ltd 2008
Formation of metamorphic rocks
Sedimentary rocks are turned into metamorphic rocks by the extreme pressures and temperatures deep within the Earth.
These conditions change the structure of the rocks so that new layers are formed.
Heat and pressure compress grains
Grains form orderly layers
Mixture of grains in structure
pressure
heat
more pressure
more heat
7 of 47 © Boardworks Ltd 2008
How are igneous rocks formed?
Magma is a type of molten rock found deep underground. Occasionally magma rises up through the Earth’s surface, causing volcanic eruptions.
When magma cools above the surface, extrusive igneous rocks are formed.
Igneous rocks are formed when the magma cools and solidifies.
When magma cools below the surface, intrusive igneous rocks are formed.
extrusive igneous
rock
intrusive igneous
rock
magma
8 of 47 © Boardworks Ltd 2008
The rock cycle
9 of 47 © Boardworks Ltd 2008
From weathering to sedimentation
10 of 42 © Boardworks Ltd 2008
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.
11 of 42 © Boardworks Ltd 2008
Freeze-thaw weathering in action
12 of 42 © Boardworks Ltd 2008
Plants and weathering in action
13 of 42 © Boardworks Ltd 2008
Examples of chemical weathering
How has chemical weathering affected these rocks?