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