Coastal Landscapes in the UK

• The coast can be defined as the meeting point between land and sea
• Coastal processes


  • Marine processes (offshore, water-based)
  • Terrestrial processes (onshore, land-based)
• Coastal processes


  • Wave action
  • Erosion
  • Transportation
  • Weathering
  • Mass movement
• Coastal processes produce the distinctive landforms found around our coastlines
• Wave action


  Waves erode, transport and deposit material
• Waves


  • Their height and strength are dependent on the fetch, the amount of time the wind blows, and the strength of the wind
  • As a wave enters shallow water, friction from the seabed causes the wave to lean forward and eventually crest and break onto the beach
• Swash


  The movement of water up the beach
• Backwash


  The return movement of water down the beach
• Wave types


  • Destructive waves (erode the beach)
  • Constructive waves (beach builders)
• Constructive waves are beach builders and destructive waves are the destroyers
• Weathering


  The break-down of rock in-situ, without the movement of material
• Types of weathering


  • Mechanical (freeze-thaw)
  • Chemical
  • Biological
• Freeze-thaw weathering


  • Water gets into cracks, freezes and expands, then thaws and contracts, widening the cracks over time
• Chemical weathering


  • Rainwater is slightly acidic and reacts with minerals in the rock, creating new material

  Faster in warmer temperatures
• Biological weathering


  • Plants and burrowing animals can physically break apart rock over time
• Mass movement


  The downhill movement of material under the influence of gravity
• Types of mass movement

  • Soil creep
  • Flow
  • Slide
  • Fall
  • Slump
• Soil creep


  • Slow movement of less than 1cm per year, caused by soil expansion and contraction
• Flow


  • Occurs on slopes 5-15 degrees, with speeds 1-15km per year, caused by saturated soil
• Slide


  • Movement of material 'en masse' that remains together until hitting the bottom of the slope
• Fall


  • Rapid movement on steep slopes, caused by weathering, rainfall, earthquakes, or hot weather
• Slump


  • Rotational slip of a large area of land on weaker rock types like clay
• Erosion is mainly caused by destructive waves
• Ways waves erode


  • Hydraulic power/action
  • Attrition
  • Abrasion
  • Corrosion
• Longshore drift


  The main process of deposition and transportation along the coast, where material is transported in a zig-zag motion by the swash and backwash
• Deposition occurs when the velocity of water flow slows down, causing material to be dropped
• Beaches are formed of sediment deposited in bays, and saltmarshes/mudflats are formed in sheltered estuaries behind spits
• Geology


  • Shapes the coastline over time, with softer rocks eroding more easily to form low, flat landscapes, and harder rocks forming rugged, steep landscapes
• Effects of rock type on the coastline

  • Hard rock: high, steep cliffs with bare, rugged faces and boulders at the foot

  Soft rock: generally lower, less steep cliffs with smoother faces and fewer rocks at the foot
• Headlands and bays


  Occur where there are alternating bands of hard and soft rock running perpendicular to waves, with the soft rock eroding to form a bay and the hard rock protruding as a headland
• Hard Rock


  • Shape of cliy: High and steep
  • Cliy face: Bare rock and rugged
  • Foot of cliy: Boulders and rocks
• Soft Rock


  • Shape of cliy: Generally lower and less steep
  • Cliy face: Smoother; evidence of slumping
  • Foot of cliy: Few rocks; some sand and mud
• Geology shapes the coastline vertically through the height and profile of a cliy and horizontally with bays and headlands
• Headlands and bays


  • Occur where there are alternating bands of hard and soft rocks run perpendicular to oncoming waves (discordant coastline)
  • Soft rock (e.g. clay) is eroded backward, forming an inlet
  • As the inlet continues to erode it curves inwards, and a bay is formed, usually with a beach
  • The hard rock (e.g. limestone) is left protruding out to sea as a headland
• Headland


  • Cliys along its sides
  • Projects out to sea
  • Usually longer than it is wide
  • Geology is of resistant rock
• Bay


  • A wide, open entrance from the sea
  • A roughly, semi-circular shape extending into the coastline
  • Land that is lower than the headlands surrounding it
  • May or may not have a beach
• Cliy formation


  1. Erosion and weathering processes

  2. Soft rock erodes quickly and will form sloping cliy faces

  3. Steep cliys are formed where there is hard rock facing the sea
• Wave-cut platform formation


  1. Wave attack the base of a cliy between the high and low water mark, forming a wave-cut notch

  2. Abrasion, corrosion and hydraulic action further extend the notch back into the cliy

  3. Undercutting of the cliy leads to instability and collapse

  4. Backwash carries away the eroded material, leaving behind a wave-cut platform
• Cave, arch, and stack formation

  1. Wave refraction concentrates erosive action on all sides of the headland

  2. Erosional processes attack weaknesses in the headland, forming a crack that widens into a cave

  3. Abrasion wears away the forming cave, making it larger until it breaks through the headland to form an arch

  4. The arch base becomes wider and thinner through erosion, until the roof collapses, leaving a stack

  5. The stack is undercut at the base by wave action and weathering until it collapses to form a stump
• Attrition is not part of the formation of caves, arches, stacks and stumps. Corrosion and sub-aerial weathering are active parts of the formation.