Landscapes & Features of The Littoral Zone (Edexcel A Level Geography)

The coast as a system

• As with any geographical system, the coast, as a system, has inputs, stores, transfers and outputs
• The system constantly strives to be in a state of dynamic equilibrium
• The coast can be viewed as both an open system and a closed system 
  • It is an open system because it receives inputs from the lithosphere, atmosphere, hydrosphere, biosphere and cryosphere
  • However, during research and coastline management the coast can be seen as a closed system where a specific sediment cell is examined

The coast as a system

• There are examples of positive feedback at the coast
• As waves erode the cliff, material is released
• This material abrades the cliff which results in even more cliff erosion 
• There are also examples of negative feedback at the coast 
• As the shore is eroded, the material makes the wave-cut platform wider
• This can absorb wave energy and reduce the impact at the base of the cliff

The littoral zone

• The littoral zone is the area of the coast that can be affected by wave action
• It is a dynamic zone which means that it is constantly changing due to the interaction between processes on land and in the sea 
• These changes can be:
  • Long-term due to climate or sea level change
  • Short term due to the tides, waves, and storms
• It is divided into four zones:
  • Backshore is usually beyond the influence of wave action but can be affected during storm events
  • Foreshore is the intertidal area between high and low tide
  • Nearshore is the breaker zone where friction between the seabed and the waves causes them to break
  • Offshore is the area outside the influence of waves

The littoral zone 

• Coastal systems are affected by long term factors which include geology and changes in sea level 

Geology

• The geology is the characteristics of the land which includes both:
  • Rock type
  • Rock structure
• Coasts can be classified as:
  • Rocky
  • Sandy
  • Estuarine
• They can also be classified as: 
  • Concordant - where different rock types run parallel to the coast
  • Discordant - where different rock types run at right angles to the coast

Sea level change

• Sea level change can occur as a result of:
  • Global warming - natural and enhanced
  • Tectonic activity - which can lead sections of land to rise or subside
• Longer-term sea level change can be:
  • Eustatic - when the sea level itself changes 
  • Isostatic - when the land rises or falls relative to the sea
• This leads to coasts that are either emergent or submergent

• Coasts can also be categorised by short-term factors:
  • Waves - can be constructive or destructive
  • Tides - tidal range is the difference between high and low tide
  • Rivers
  • Storm events
• These create coastlines that can be:
  • Retreating or advancing which depends on whether erosion or deposition dominates
  • Dominated by land-based processes (primary coasts) or marine processes (secondary coasts)
  • Large or small tidal range 
  • High or low-energy 

Characteristics of High and Low Energy Coasts

High Energy Coasts	Low Energy Coasts
Destructive waves Exposed to strong winds and long fetches Higher rates of erosion than deposition Tend to be rocky coasts Steep cliffs - marine cliff profile Less steep cliffs - subaerial cliff profile Headlands, wave-cut platforms	Constructive waves Sheltered locations with short fetch Higher rates of deposition than erosion Sandy beaches, salt marshes, estuarine and tidal mud flats Gentle relief  Sediment from land and sea Beaches, spits, coastal plains

• Rocky coasts form where there is more resistant geology - in the UK this is mainly in the north and west of the country
• Cliffs of varying heights and steepness can be found along rocky coastlines:
  • Steep cliffs tend to be found in high energy environments
  • Cliffs with a gentler slope tend to be found in low energy environments
• Erosion is more dominant than deposition
• Two types of erosion may dominate along rocky coastlines:
  • Marine erosion - the action of waves
  • Sub-aerial erosion - weathering and mass movement

• Coastal plains usually occur where the land gradually slopes down towards the sea
• Tend to be low relief
• Coastal plains include both:
  • Sandy coastlines
  • Estuarine coastlines

• These are usually low energy coastal environments
• They form due to coastal accretion - when deposition is greater than erosion
• Sediment for deposition comes from:
  
  • Offshore sources
  • Terrestrial sources
• Dunes form, helping to stabilise the coast and reduce erosion
• Wetlands and marshes form due to poor drainage
• Estuarine coastlines form at the mouths of rivers and are formed from clay and silt