Coasts a level geography edexcel

• The UK's coastline is an incredible 31 368 km long (if you include all the main islands)

  
• Resistant rock coastlines


  Coastlines that can withstand frequent winter storms without suffering from rapid erosion
• Resistant rocks in western Britain

  • Igneous rocks (such as basalt and granite)
  • Older compacted sedimentary rocks (such as old red sandstone)
  • Metamorphic rocks (such as slates and schists)
• Coastal plain landscapes


  Areas of weaker and younger sedimentary rocks - including chalks, clays, sand and sandstone

  
• Coastal plain landscapes


  • The Wash
  • Bamburgh beach in Northumberland
  • Holiday resorts on the Lincolnshire and Norfolk coasts
• High-energy coastlines

  • Rocky coasts are generally found in high-energy environments where the waves are powerful for much of the year and the rate of erosion exceeds the rate of deposition
  • Erosional landforms such as headlands, cliffs, and shoreline platforms tend to be found in these environments

  
• Low-energy coastlines


  • Sandy and estuarine coasts are generally found in low-energy environments where the waves are less powerful or the coast is sheltered from large waves and the rate of deposition exceeds the rate of erosion
  • Landforms such as beaches, spits and coastal plains tend to be found in these environments

  
• Many coasts are a mixture of high- and low-energy environments
• Littoral zone


  The boundary between land and sea, a zone rather than a line because tides and storms affect a band around the coast
• The littoral zone is constantly changing due to short-term factors (such as individual waves, daily tides and seasonal storms) and long-term factors (such as changes to sea levels or climate change)
• Sections of the littoral zone


  • Backshore
  • Foreshore
• Sediment supply


  The sources of sediment that produce coastal landforms through weathering, erosion, transport and deposition
• Sources of sediment for The Wash

  • Cliffs eroding between West Runton and Weybourne, east of The Wash
  • Tidal currents picking up glacial deposits from the shallow sea floor
  • Erosion of the Holderness cliffs further north
  • Sand carried southwards along the Lincolnshire coast
  • Sediment discharged by four rivers
• The Wash and the Norfolk coastline form part of one of eleven sediment cells around the English and Welsh coasts
• Classifying coasts


  Can be based on geology, energy level, balance between erosion and deposition, and changes in sea level

  
• No classification system is definitive as coasts often have a mixture of characteristics
• Lulworth Crumple


  An example of limestone folding at Stair Hole on the Jurassic Coast, caused by tectonic movements about thirty million years ago
• Coastal morphology


  Related to the underlying geology or rock type, as well as its geological structure (lithology)

  
• Characteristics of lithology


  • Strata - layers of rock
  • Bedding planes (horizontal cracks)
  • Joints (vertical cracks)
  • Folds
  • Faults
  • Dip - angle at which rock strata lie
• There is a direct relationship between rock type, lithology, and cliff profiles

  
• Bedding planes


  Horizontal cracks, natural breaks in the strata caused by gaps in time during periods of rock formation
• Joints


  Vertical cracks, fractures caused by contraction as sediments dry out or by earth movements during uplift
• Folds


  Formed by pressure during tectonic activity, which makes rocks buckle and crumple (e.g. the Lulworth Crumple)
• Faults


  Formed when the stress or pressure to which a rock is subjected exceeds its internal strength, causing it to fracture and slip or move along fault planes
• Dip


  The angle at which rock strata lie (horizontally, vertically, dipping towards the sea, or dipping inland)

  
• The relief - or height and slope of land - is also affected by geology and geological structure. There is a direct relationship between rock type, lithology, and cliff profiles.
• Coastal morphology


  The shape and form of coastal landscapes and their features

  
• Coastal recession


  Another term for coastal erosion
• Lithology


  The physical characteristics of particular rocks
• Igneous rocks


  • Crystalline, resistant and impermeable
• Metamorphic rocks


  • Very hard, impermeable and resistant
• Unconsolidated materials


  • Loose, such as the boulder clay of the Holderness coast, not cemented together and easily eroded
• Geology and lithology play key roles in the type of cliff profile produced, and the rate at which coasts erode or recede. Other processes, such as weathering and mass movement, also affect the rate of erosion or recession.
• Concordant coast


  Bands of more-resistant and less-resistant rock run parallel to the coast

  
• Discordant coast


  The geology alternates between bands of more-resistant and less-resistant rock, which run at right angles to the coast
• The eastern coast of the Isle of Purbeck is discordant, with more-resistant rocks (folded into ridges) emerging at the coast as headlands and cliffs, whilst less-resistant rocks form bays.
• Headlands, such as The Foreland and Peveril Point, jut out into the sea, with bays (such as Swanage Bay) lying between them. Headlands and bays commonly form when rocks of different strengths are exposed at the coast.

  
• More-resistant rocks, such as chalk and limestone (or igneous and metamorphic rocks) tend to form headlands, whilst weaker rocks (such as shale and clays) are eroded to form bays.
• When waves approach a headland, the depth of the water decreases, causing the waves to get higher and steeper, with increased erosive power. When waves enter a bay, the water is deeper, so they do not lose velocity as rapidly, allowing deposition rather than erosion to take place.
• Wave movement


  Water particles move in circular orbit as waves move – or ripple – across the surface