Geography revision (Physical)

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Coast -  A dynamic narrow zone where land meets the sea. Coastlines are constantly changing due to the process of erosion, transportation and deposition.

If their wasn't a seabed then the waves would just orbit in a circular motion. The friction with the waves and the seabed disorts the circular orbital motion.

Fetch - The length over the water over which the wind has blown, affecting the size and stength of the wave.

Destructive waves

They are often steep, high waves that are close together and crash down onto the beach. It was a weak swash and strong backwash which pulls sand and pebbels back into the sea when the water retreats.

Constructive waves

They are often low waves which have a large gap between each wave. It has a strong swash and a weak backwash which pushes the sand and pebbles back up onto the beach.

Weathering - Weathering is the breakdown or decay of rocks by the elements of the weather.

Thermal expansion: Expand (heat) Contract (cool)

The main casuse of sea level rise is the thermal expansion of the sea water as it absorbs more heat from the atmosphere. The melting of ice on land for example, the glaciers. Thermal expansion results in the expansion of the volume of water causing sea levels to rise.

Types of weathering

Phyiscal or mechanical weathering

Freeze thaw: Water gets into the cracks of rocks and it freezes causing it to expand and then break.

Thermal expansion: The rock gets warm and expands and when it cools down it contracts. Layers in the rock crack due to the frequent temperature change.

Chemical weathering

When water comes into contact with calcium carbonate it disolves some of the rock.

Biological weathering

Tree roots: The roots of the tree grow into the cracks of rocks and cause it to break.

Hydraulic action: Water is forced into the cracks of the rock which compresses the air inside. When the wave retreats the compressed air blasts out and forces the rock apart.

Abrasion: Loose rocks (sediment) are thrown against the cliff by waves. It wears the cliff away and chips parts off the rock.

Attrition: Loose sediment knockd off the cliff from hydraulic action and abrasion is swirled around by the waves. It constantly collides with other sediment and gradually gets worn down into smaller parts.

Landforms caused by erosion

  • There is cracks in the rock
  • Abrassion and hydraulic action causes the crack to widen into a cave
  • It will eventually break through to the otherside and form an arch
  • The arch will become weak and collapse
  • This will leave a stack
  • The stack gets eroded and forms into a stump

Sandy beaches tend to be flat or have a gentle slope. Beaches are made up of ereoded material that has been transported and deposited by the sea. Constructive waves deposit material when they break on a shore in a sheltered bay because they run out of energy. The material found on the beach depends of the…

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