Coasts booklet 1

• Littoral zone


  The breakwater area where waves come onshore, nearest to the coastline where high and low tides happen
• Sections of the littoral zone

  • Offshore
  • Nearshore
  • Foreshore
  • Backshore
• Offshore


  • Farthest section out to sea, deepest area where waves start to break
• Nearshore


  • Closer to coast, area of shallow water beyond low tide mark, more friction between seabed and waves distorts the waves
• Foreshore


  • Area between high and low tides, covered in water during high tide and exposed during low tide
• Backshore


  • Area above high tide mark, affected by wave action only during storm events
• Types of coastlines


  • Rocky/cliff
  • Sandy
  • Estuarine
• Rocky/cliff coastline


  • High relief, resistant rock, high energy environment, erosion greater than deposition, destructive waves
• Sandy coastline


  • Low relief, soft rock, deposition greater than erosion, constructive waves with strong swash and weak backwash
• Estuarine coastline


  • Low relief, salt marshes, river mouth, deposition greater than erosion, low energy environment
• Dynamic equilibrium


  Balance between inputs of sediment, outputs, and flows of sediment due to energy at the coastline
• Short-term coastal classifications


  • Tides
  • Currents and river flows
  • Precipitation
  • Gravity and tectonics
  • Sediment inputs and deposition/erosion rates
  • Advancing/retreating coastlines
  • Emergent/submergent coastlines
• Long-term coastal classifications


  • Geology/lithology
  • Concordant/discordant coastlines
  • Sea level changes
  • Tectonic plate movements
  • Climate change
• Rocky coastline in UK

  • Around 1000km, mainly in north and west, resistant geology, high energy erosion but slow erosion rates, little deposition
• Sandy plain coastline in UK

  • Flat or gently sloping, wetlands and salt marshes, low energy environment, high deposition rates, can be sand, shingle or cobbles, mainly in south and east
• Concordant coastline


  Rock runs parallel to the sea in one consistent band
• Discordant coastline


  Differing bands of hard and soft rock perpendicular to the sea
• Other coastline examples


  • Dalmatian coastline of Croatia
  • Half coasts (sand bars)
• Dalmatian coastline


  • Formed by anticlinal ridges and synclinal valleys, submergent coastline with harder rock bands remaining as islands
• Half coasts


  • Unconsolidated sand ridges forming bars across bays, formed by deposition over time
• Coastal dip


  Angle of rock from horizontal, affects profile and vulnerability to erosion
• High angle seaward dip


  • Slow, low sloping profile vulnerable to subaerial processes and weathering
• Low angle seaward dip


  • Steeper profile exceeding 90 degrees, leading to major cliff collapse from undercutting
• Faults


  Major fractures in rock created by tectonic plates, increase rate of erosion
• Joints


  Fractures in rock that also increase erosion rates
• Degrees which produces a slow low sloping angled profile with run lock fade one lock facing the sea


  • These are vulnerable coastlines and are vulnerable to be attacked by subaerial processes and weathering
• Low angle of sea wood dip


  • Produces a steeper profile of the rock which may even exceed 90 degrees
• Undercutting of the rock


  Leads to major cliff collapse
• Faults


  • Major fractures created by tectonic plates, they create a fault line, they increase the rate of erosion and this leads to rocks easily being eroded over time
• Joints


  • Fractures without the rock being moved, caused by weathering and compression
• Fissures


  • More open than fractures, deeper open ravines in rock
• Folding


  • Bends that occur in rock, producing a layering effect, main types are anticlines and synclines
• Rock type in bedrock at the sea

  Influences the rate of coastal recession or retreat, influenced by how reactive the rock is to chemicals, whether it's a less resistant type of rock or a more resistant
• Types of igneous rocks

  • Granite
  • Dolorite
  • Basalts
• Igneous rocks


  • Erode very slowly and weather very slowly, crystals are interlocking, few joints and weaknesses, most resistant type of rock
• Types of metamorphic rocks

  • Marble
  • Slate
  • Schist
• Metamorphic rocks


  • Recrystallized or reformed through heat and pressure, crystalline structure, less resistant than igneous but more resistant than sedimentary
• Types of sedimentary rocks

  • Sandstones
  • Limestones
  • Clays
• Sedimentary rocks


  • Formed by compression and compaction, least resistant type of rock, have lots of joints and cracks, moderate erosion rates
• Unconsolidated sedimentary material


  Alluvium, not yet cemented or compacted sand and other types of rocks, very easily eroded at around 2-10 meters per year