Igneous rocks Igneous rocks are formed either underground as magma, deep within the earth becomes trapped in small pockets and cools or above ground as lava after volcano erruptions cool down.
Metamorphic rocks Metamorphic rocks are rocks that have 'morphed' into another kind of rock. These rocks were once igneous or sedimentary rocks, but were subjected to intense pressure and heat
Sedimentary rocks Sedimentary Rocks are formed as sediment from the bottom of rivers, lakes and oceans settles. Layer after layer is deposited on top of each. These layers are pressed down more and more through time, until the bottom layers slowly turn into rock.
Pyroclastic rocks Pyroclastic rocks are formed from lavas which are ejected into the air, as occur in pyroclastic flows or Plinian eruptions. They include pumice, volcanic bombs, ignimbrite and ash.