Types of Rock
- Forms when molten magma/ lava cools and solidifies.
- If it's cooled on the surface it has small crystals, like basalt.
- If it cooled underground it has large crystals, like granite.
- Forms when sediment (tiny particles) settle on the ocean floor and the layers build up. The pressure causes the layer to harden.
- Chalk and limestone, made from shells of sea creatures that fell to the ocean floor.
- Formed from sedimentary rock thats come under heat and pressure underground. This makes the arrangement of crystals in the rock change.
- Limestone and chalk change to marble when they come under heat and pressure.
Rate of cooling affects the crystal size of igneous rocks.
- Intrusive igneous rock cools slowly underground because it is insulated by the surronding rocks. Forms large crystals.
- Extrusive igenous rock cools quickly above ground. Forms small crystals.
Crystals are formed by atoms fitting together in rigid structures with regular lines and layers.
- The amount of kinetic energy in atoms is related to their temperature.
- As molten rock cools, the amount of energy in particles reduces. They bond to make crystals.
- If cooling is slow, the amount of crystals is small but they are large.
- If rapid, vast amounts are made, but they are small.