Weathering and erosion work at different speeds on different types of rock.
Formed from volcanic rock.
If the magma cools underground, granite is formed.
If the magma reaches the Earth's surface, it is called lava, which then forms basalt when it cools.
Formed when rivers transport particles of rock and remains of plants and animals to the sea.
These then sink to the bed and, over millions of years, compress to form new rock.
Formed from sedimentary or igneous rock when it is exposed to extreme pressure or heat during the Earth's movements, for example, chalk and limestone turn to marble; clay turns to slate.