Geography Paper 1 - Physical (coasts and rivers)

• Destructive Waves


  A wave that tends to erode the coastline. They are usually large, frequent and powerful. They are created during storm conditions.

  
• Constructive Waves


  A wave that tends to build up the coastline. They are small, infrequent waves which are less powerful and are created during calm weather.

  
• Coastline


  The interface between the land and sea. It includes physical features and processes and economic activity.

  
• Shoreline


  The zone between high tide and low tide.

  
• Erosion (coastal)


  The shaping of the coast by the destructive action of the sea.

  
• Deposition


  The shaping of the coast by the constructive action of the sea.

  
• Transportation


  The movement of material around coastlines by the action of the sea. Prevailing wind will blow waves across the coast, which will carry sediment.

  
• Swash


  The forward motion of a wave which tends to deposit sediment.

  
• Backwash


  The backwards movement of a wave which tends to erode the coastline.

  
• Hydraulic Action


  A type of erosion. This is the pressure of water being thrown against the cliff face. It also includes the compression of air in cracks.

  
• Corrosion (solution)


  A type of erosion. This is a chemical reaction between certain rock types (e.g. chalk) and dilute acid in the seawater.

  
• Corrasion (abrasion)


  A type of erosion. It occurs when waves carry pebbles and sand which then scour the cliff face and break off more rock. This starts a cycle.

  
• Attrition


  A type of erosion between boulders in the sea. As the boulders roll around they get chipped and eventually form pebbles and sand.

  
• Fetch


  The distance of open ocean over which the wind can whip up waves.

  
• Prevailing wind


  The most common wind direction.

  
• Dominant wind


  The direction from which the strongest winds tend to come.

  
• High Energy Coastlines


  Coastlines which receive a lot of wave energy. They usually suffer from erosion but it depends on the geology in the area.

  
• Low Energy Coastlines


  Coastlines which receive little wave energy.

  
• Differential erosion


  This type of erosion forms physical features on the coastline such as headlands and bays. It occurs when less resistant rocks are eroded more quickly than resistant rocks (e.g. boulder clay and limestone).

  
• Collapse

  This is a type of mass movement. It occurs when waves erode the base of a cliff and create an overhang, which collapse along the weakness due to gravity when it is saturated with water (from various weathering processes like rain).
• Slumping


  This is a type of mass movement. When a permeable rock like chalk sits on top of an impermeable rock like clay, water builds up in between the two layers (when it rains). The water lubricates the slip plane and the top layer collapses into the sea.

  
• Weathering


  When rock is eroded slowly through physical processes such as rain. Can be chemical (acid rain), physical (freeze-thaw action) or biological (plant roots or animal burrows).

  
• Bay


  A physical feature formed as a result of differential erosion. It is an inlet formed where the land curves inwards (they tend to form from less resistant rocks).

  
• Headland


  A physical feature formed as a result of differential erosion. It is a stick of land that juts out in to the sea (it is usually formed from more resistant rocks).

  
• Cave

  When a headland is eroded by the sea, a crack opens up in the rock.

  
• Arch


  When the seawater erodes right through the back of the cave, an arch is formed.

  
• Stack


  They form when the roof of an arch collapses due to gravity (after it has been weathered sufficiently). This isolated piece of land is left in the sea.

  
• Stump


  They form when the sea erodes the base of a stack so much that it collapses.
• Wave cut platforms


  Flat platform of rock formed as a result of cliff retreat. These form the basis of beaches (as a surface for the sediment to be deposited on).

  
• Longshore Drift


  This process transports sediment along the coast which is eroded by attrition as it moves (so it ends up smoother after a while). It occurs when constructive waves roll in oblique (diagonally) to the coastline but straight back due to gravity. This moves sediment along the coastline. It also forms spits, bars and tombolos.

  
• Beach


  This is simply an accumulation of deposited material along the coast between high and low tide. They are usually formed on wave cut platforms.

  
• Spits


  These features form as a result of longshore drift. When waves reach shallow water of an area with little wind they drop the sediment they are carrying (due to increased friction) which forms this feature.

  
• Bars


  These are features formed when longshore drift cuts across a bay and deposits the sediment it is carrying (due to the change in depth- there is increased friction).

  
• Tombolos


  These features are formed when a spit or bar joins on to an island separate from the mainland (they are like "land bridges" joining them up).

  
• Salt marshes


  These features form behind spits when seawater accumulates but is unable to drain away. They make great habitats for wading birds and other wildlife.

  
• Strategy


  The plan to manage the coastline (relevant to coastal management).
• Advance the line


  A coastal management strategy which involves pushing the coastline further towards the sea e.g. Bournemouth.

  
• Hold the line


  A coastal management strategy which tries to keep the coastline where it is now e.g. Southend-on-Sea.

  
• Managed retreat


  A coastal management strategy which allows erosion to occur whilst dealing with the consequences e.g. Abbots Farm, Essex.

  
• Soft engineering


  A type of technique which uses natural materials e.g. beach replenishment.