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

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

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.

Wave Types:

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

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