GCSE Geography: Rocks - Igneous, Metamorphic and Sedimentary

23rd August 2017

GCSE Geography Revision - Made Easy!

All you need to know about Igneous, Metamorphic and Sedimentary Rocks!


Our planet's surface is sculpted by rocks. The rocks you see today have all actually come from the Earth's interior. They are classified into 3 groups based on their shared characteristics: Igneous, Metamorphic, and Sedimentary. Each have very specific characteristics and were formed in very different ways.


  • Igneous - These rocks were all formed by magma, from the planet's molten interior. When magma erupts it finds a way up through the Earth's crust and surface, and when it reaches it, it cools to form volcanic landforms. Magma can however, cool inside the earth - these are called intrusive rocks. These may take thousands of years to show, but erosion and weathering may expose them at some point. Examples of igneous rock include granite and basalt.


  • Metamorphic - These rocks were originally one of the other two types of rock. However they have become classified as metamorphic because they have been subjected to such intense heat and pressure that they have transformed into a different type of rock altogether. For example, slate was originally clay, and marble was originally limestone, however both were transformed from intense heat and pressure. Becuase of the pressure and heat the rocks have been created by, it means metamorphic rocks are extremely hard, and are relatively unaffected by weathering and erosion.


  • Sedimentary - These rocks have been formed from sediment material that has settled underneath a large body of water. The sediment is made from other eroded rocks or remnants of sea creatures, transported to a body of water by rivers or ice. Over millions of year the sediment has been compressed by the weight and pressure of the large body of water above it, and has formed rock formations. Examples of sedimentary rock include sandstone, chalk and clay.


Make sure to watch our music video on Igneous, Metamorphic and Sedimentary Rocks, try to remember the lyrics, and then take a shot at our test!


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