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Edexcel GCSE Geography - Physical Landscapes Revision

Physical Landscapes

Classification of Rocks:

  • Igneous Rocks -
    • Formed by magma from the molten interior of the Earth
    • If magma cools inside the Earth it forms intrusive rock, which may later be exposed by erosion and weathering, e.g. granite.
    • If magma erupts on the surface as lava, it will form extrusive rock, e.g. basalt.
    • As the magma cools, mineral crystals will begin to grow. These crystals will grow and interlock to form a hard crystalline rock.
  • Sedimentary Rocks -
    • Sedimentary rocks are formed from sediment (from eroded rocks and cliffs) that has settled at the bottom of a lake, sea or ocean, and have been compressed with pressure over millions of years.
    • Examples of sedimentary rocks include limestone, sandstone, chalk and mudstone.
    • The weathered and eroded material is built up in layers. As more material is added on top – this will push any air and/or water out and will compact the material together into a hard rock.
    • Often contain fossils
  • Metamorphic Rocks -
    • Metamorphic rocks have been subjected to lots of heat and / or pressure, causing them to change into another type of rock.
    • They are usually resistant to weathering and erosion and are therefore very hard-wearing, making them good building materials.
    • Examples of metamorphic rocks include marble, which originates from limestone and slate, which originates from clay.
    • These are formed when either igneous or sedimentary rocks are changed.

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Coasts:

Longshore Drift:

  • Waves are forced against the cliffs at angles due to prevailing winds
  • This takes sediment with it and pushes it further down the cliff
  • This continues over years, pushing this further down the cliff

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Weathering:

  • Physical Weathering -
    • Water gets into a crack in a rock
    • At night, this freezes and expands
    • This continues until the rock falls off the cliff
  • Chemical Weathering -
    • Rainwater is slightly acidic
    • As this falls against the cliffs, it slowly wears it down
    • Over years, these rocks become dissolves
  • Biological Weathering -
    • A plant grown in a crack in a rock
    • As this grows, it requires more space, widening this crack
    • Over time, this plant pushes the rock away from the cliff

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Mass Movement:

  • The downhill movement of sediment moving because of gravity.
  • Rockfall -
    • Bits of rock fall off the cliff face, usually due to freeze-thaw weathering.
  • Mudflow -
    • Saturated soil (soil filled with water) flows down a slope.
  • Landslides -
    • Large blocks of rock slide downhill.
  • Rotational Slip -
    • Saturated soil slumps down a curved surface.

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Wave Types:

  • Destructive Waves -
    • Waves that attack the cliff face to erode rock
  • Constructive Waves -
    • Waves that take up the sediment from eroded rock

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Rivers:

Floodplains and Levees:

  • A river deposits sediment to its banks
  • Every 2 - 3 years, this river floods
  • This deposits sediment onto the sides of the river
  • This sediment forms natural walls on the sides of the rivers, called floodplains or levees
  • This is a natural flood defence

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