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Classification of rocks

There are three types of rock: igneous, sedimentary and metamorphic. Watch this video to find out more.


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Key points

  • Igneous rocks like basalt and granite are formed when molten magma from the Earth's interior cools.
  • It either cools on the Earth's surface after a volcanic eruption or inside the Earth to form intrusive rock.
  • Metamorphic rocks have been subjected to massive heat or pressure and are usually very hard wearing. Examples are marble and slate.
  • Sedimentary rocks are formed from sediments at the bottom of a lake or sea, which compress over millions of years. Examples are sandstone, limestone and clay.

All Geography videos

Rock landscapes and processes index

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