S-Cool Revision Summary

S-Cool Revision Summary

The atmosphere is a layer
of gas
around the Earth.

Air is a mixture of gases. It is most dense at sea-level
and thins out as we rise through the layer of atmosphere called the troposphere.

The Earth formed about 4600 million years
ago.

The ozone layer protects us from the
Sun's most harmful ultraviolet rays.

The atmosphere is maintained by nature recycling substances in living things.
All living things depend upon oxygen, nitrogen,
carbon dioxide
and water.

The Earth's surface is formed and forever changing by different processes occurring.

Igneous rocks are formed from the
hot liquid rock (molten magma) from volcanoes
solidifying.
Interlocking crystals are often found in these rocks.

Sedimentary rock is formed from sediments.
Due to weathering and erosion, larger rock may crumble into smaller ones and
be transported until they eventually settle on sea or riverbeds. Over the years
these fragments of rock compress together. Sedimentary rock is often crumbly
due to its formation from small bits of rock. Often they are layered, and on
some occasions fossils may be present.

Metamorphic rock occurs when heat
or pressure or both cause a rock to change its structure.