Edexcel Geography A-level: Coastal Landscapes and Change Flashcards

Coastal Systems and Sediment Cells

  • Coasts are open systems involving terrestrial, atmospheric, and oceanic inputs/outputs.
  • England and Wales are divided into 1111 sediment cells, typically managed as closed systems.
  • Components of cells include Sources (cliffs, offshore bars), Through flows (Longshore Drift), and Sinks (spits, beaches).
  • Negative feedback loops (e.g., offshore bars dissipating wave energy) return the system to dynamic equilibrium.
  • Positive feedback loops (e.g., vegetation destruction on dunes) take the system away from equilibrium, increasing erosion.

The Littoral Zone and Classification

  • The Littoral zone includes the Backshore (above high tide), Foreshore (wave process area), and Offshore (open sea).
  • Valentine’s Classification categorizes coasts as Advancing (emerging land or depositional) or Retreating (submerged land or erosional).

Coastal Erosion and Rock Resistance

  • Erosive processes include Corrasion (pelted sediment), Abrasion (scouring), Attrition (rocks hitting rocks), Corrosion (CO2CO_2 reacting with limestone), and Hydraulic Action (air compression in cracks).
  • Wave Quarrying can exert pressures up to 30 tonnes per m230\,\text{tonnes per m}^2.
  • Vulnerability depends on lithology: Igneous rocks erode at <0.1 cm/year<0.1\,\text{cm/year}, Metamorphic at 0.1−0.3 cm/year0.1-0.3\,\text{cm/year}, and Sedimentary at 0.5−10 cm/year0.5-10\,\text{cm/year}.

Coastal Landforms

  • Erosional Landforms: The sequence of Caves, Arches, Stacks, and Stumps, and Wave-cut platforms.
  • Transport: Primarily Longshore (Littoral) Drift (LSD) alongside Traction, Saltation, Suspension, and Solution.
  • Depositional Landforms: Spits, Bars (linking two coast sections), Tombolos (connecting mainland to island), Cuspate Forelands, and Sand Dunes.
  • Sand Dune Succession: Stages move from Embryo dunes to Yellow, Grey, Dune slack, and finally Climax Woodland (Heath).

Sub-Aerial Processes and Geologic Structure

  • Weathering: Mechanical (Freeze-thaw/10%10\% volume expansion), Chemical (Carbonation, Oxidation, Solution), and Biological (roots, birds).
  • Mass Movement: Includes Flows (Soil creep, Solifluction, Mudflows) and Slides (Rock falls on slopes >40∘>40^{\circ}, Rock slides, and Slumps).
  • Concordant Coastlines: Strata run parallel to the coast (e.g., Dalmatian and Haff coasts).
  • Discordant Coastlines: Strata run perpendicular, creating Headlands and Bays due to differential erosion rates.

Waves and Sea Level Change

  • Constructive waves: Low frequency, strong swash, depositional.
  • Destructive waves: High frequency, strong backwash, erosional.
  • Isostatic Change: Local adjustment; Scotland is rising at 1.55 mm/year1.55\,\text{mm/year}, while Southern England subsides at 1 mm/year1\,\text{mm/year}.
  • Eustatic Change: Global rise due to thermal expansion of water from global warming.

Coastal Management Strategies

  • Management Policies: Hold the line, Managed realignment, Advance the line, and Do nothing.
  • Frameworks: Integrated Coastal Zone Management (ICZM) and Shoreline Management Plans (SMP).
  • Hard Engineering: Sea Walls (reflective), Groynes (trap sediment from LSD), Rip Rap (Rock Armour), and Revetments.
  • Soft Engineering: Beach Nourishment, Cliff Regrading/Drainage, Dune Stabilisation (using Marram grass), and Marsh Creation.
  • Economic assessment uses Cost-benefit analysis (CBA) to justify funding from DEFRA.