geography section C- Coastal landscapes in the UK

• Wave types


  Constructive and destructive
• How waves are created

  1. Wind blows over the sea

  2. Creates waves
• Factors affecting wave size and energy

  • Fetch - how far the wave has travelled
  • Strength of the wind
  • How long the wind has been blowing for
• Long fetch


  • South-westerly wind will produce large powerful waves
• Short fetch


  • South-easterly wind will produce small waves
• Swash


  When a wave washes up onto the shoreline
• Backwash


  The water that flows back towards the sea
• Destructive waves


  • High in proportion to their length
  • Weak swash but strong backwash
  • Tall breaker - tall wave which breaks downwards with great force
• Characteristics of destructive waves

  • Weak swash and strong backwash
  • Strong backwash removes sediment from the beach
  • Steep and close together
• Constructive waves


  • Low in proportion to their height
  • Strong swash and weak backwash
• Characteristics of constructive waves

  • Strong swash and weak backwash
  • Strong swash brings sediments to build up the beach
  • Backwash not strong enough to remove sediment
  • Low and further apart
• Weathering


  The breakdown of rocks exposed at the Earth's surface
• Freeze-thaw weathering


  1. Water enters cracks in the rock

  2. When temperatures drop, the water freezes and expands causing the crack to widen

  3. The ice melts and water makes its way deeper into the cracks

  4. The process repeats itself until the rock splits entirely
• Biological weathering


  • Plants and animals can have an effect on rocks
  • Roots burrow down, weakening the structure of the rock until it breaks away
• Biological weathering


  1. Plant roots can get into small cracks in the rock

  2. As the roots grow, the cracks become larger

  3. This causes small pieces of rock to break away
• Chemical weathering


  • Rainwater and seawater can be a weak acid
  • If a coastline is made up of rocks such as limestone or chalk, over time they can become dissolved by the acid in the water
• Types of mass movement

  • Rockfall
  • Mudflow
  • Landslide
  • Rotational slip
• Rockfall


  • Rocks fall off the cliff face forming scree at the bottom
  • Bits of rock fall off the cliff face, usually due to freeze-thaw weathering
• Mudflow


  • Saturated soil slides down the bedrock forming a lobe at the bottom with a stream running through
  • Saturated soil (soil filled with water) flows down a slope
• Landslide


  • Rocks detach off the slide plane and slide down to the bottom
  • Large blocks of rock slide downhill
• Rotational slip


  • Soil slides down a curved slip plane
  • The top is called the head, the bottom the foot
  • The soil collects at the toe
  • The wall of the curved slip plane is the scarp
  • Saturated soil slumps down a curved surface
• Erosion


  The wearing away of rock along the coastline
• Destructive waves


  • Responsible for erosion on the coastline
• Types of erosion


  • Hydraulic action
  • Abrasion
  • Attrition
  • Solution
• Hydraulic action


  The sheer power of the waves as they smash against the cliff. Air becomes trapped in the cracks in the rock and causes the rock to break apart.
• Abrasion


  Pebbles grind along a rock platform, much like sandpaper. Over time the rock becomes smooth.
• Attrition


  Rocks that the sea is carrying knock against each other. They break apart to become smaller and more rounded.
• Solution


  Sea water dissolves certain types of rocks. In the UK, chalk and limestone cliffs are prone to this type of erosion.
• Ways beach material can be moved

  • Solution
  • Suspension
  • Saltation
  • Traction
• Solution


  Minerals in rocks like chalk and limestone are dissolved in sea water and then carried in solution. The load is not visible.
• Suspension


  Small particles such as silts and clays are suspended in the flow of the water.
• Saltation


  Small pieces of shingle or large sand grains are bounced along the sea bed.
• Traction


  Pebbles and larger material are rolled along the sea bed.
• Sediment movement along the coastline

  1. Sediment is carried by the waves

  2. Waves approach the coast at an angle because of the direction of prevailing wind

  3. Swash carries the material towards the beach at an angle

  4. Backwash flows back to the sea, down the slope of the beach

  5. Process repeats itself along the coast in the zigzag movement
• Longshore drift


  The movement of the material along the coastline
• Deposition


  When the sea loses energy, it drops the material it has been carrying
• Deposition


  • Occurs on coastlines that have constructive waves
• Factors leading to deposition

  • Waves starting to slow down and lose energy
  • Shallow water
  • Sheltered areas, eg bays
  • Little or no wind
• Erosion


  The process that can create different landforms along the coastline
• Headlands and bays


  • Formed when a stretch of coastline is formed from different types of rock
  • Soft rock such as clay and sand are weaker and eroded quickly, forming bays
  • Hard rock such as chalk is more resistant, forming headlands