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