The 3 Types of Rock

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  • Rocks, Resources and Landscapes
    • Types of Rock
      • Sedimentary
        • Made of Sediment
        • Always form in water
        • Made by
          • Cementing 'clasts' (fragments)
            • Clasts can be as small as mud or as big as pebbles
          • Derived by weathering and erosion
            • Clasts carried down to sea by wind or rivers.
          • Once sediment arrives in sea, it settles on sea bed and is compacted by the weight of material that is deposited on top if it
            • As material is laid down in layers, bedding planes and faults develop
              • Makes rock open up more to weathering and erosion
        • For Example
          • Clay
            • Mud sediments
          • Chalk and Limestone
            • Calcium Carbonate
              • This is found in shells of sea creatures, who die and decay on the floor
          • Sandstone
            • Untitled
      • Igneous
        • 2 Types
          • Intrusive
            • Formed Underground
            • Cooling and Crystallisation of magma (molten rock), deep underground
              • Crystals grow as magma cools
                • Slower the cooling, the bigger the crystals, resulting in a coarse grain rock
                  • Magma cools quicker nearer the earth surface, as temperatures here are cooler
                    • This gives a fine grain rock
          • Extrusive
            • Formed on the surface
            • Form where magma has erupted onto the surface
              • It cools quickly to form a rock with very small crystals (a lava flow)
                • Lava is usually darker in colour and may have some gas holes in it
    • Metamorphic
      • Formed
        • Rocks (Sedimentary or Igneous) that have been altered
          • By heat
            • Or both
              • Transforming them into denser, more compacted rocks.
                • Sometimes new crystals grow from the old minerals which get rearranged
          • Or pressure
            • Or both
              • Transforming them into denser, more compacted rocks.
                • Sometimes new crystals grow from the old minerals which get rearranged
      • If altered by pressure
        • It is likely to show some layers of 'foliation'
          • E.G. Slate
      • If altered by heat
        • E.G. Being next to a magma chamber
        • It can have a sugary texture
          • E.G. Marble
      • Form on plate margins

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