Climate change and coast lines

• Eustatic sea level change is where the sea level rises or falls due to changes within the volume of water
• Isostatic sea level change is the change in sea level due to the movement of the land
• How is Eustatic sea level change possible?

  • higher rates of melting sea ice and glaciers whose water will be deposited into the ocean through rivers
  • When global temperatures increase water molecules can expand leading to an increased volume of water held within the ocean
  • When temperatures fall more water is stored in solids like snow and ice and therefore the sea level will fall
  • water can contract which leads to an increased density in water molecules resulting in a reducing volume of ocean water
• The current period of sea level rise is the Flandrian Transgression.
• How is Isostatic sea level change possible?

  • Geological processes like the uplift or subsidence of land masses due to the downward pressure of ice lifting allowing the land to rebound.
  • tectonic processes causing land to rise (fold mountains)
• An example of Isostatic sea level change is within the Baltic Sea area where the land is still uplifting by 40-90cm per century since the ice age
• landforms and formed by sea level rise
• RIA


  submerged or drowned river valleys which remain under water at the lower courses of the river profile.

  so more of the river valleys are exposed to marine processes like erosion, tides and deposition with mudflats being submerged
• sea level was 140m lower than it is now during the devensian glaciation
• An example of a Ria is the Knightsbridge estuary in Devon
• FJORD


  A drowned glacial valley that has much more erosive power than a river with steep cliff-like valley sides and the water being up to 1000m deep.

  found in high energy environments and are either deepened or infilled by sediment
• Areas such as the west coast of New Zealand have present glaciers and as they melt they deposit sediment into the fjords
• SHINGLE BEACH 


  Formed from rivers and glacial deposits of terrestrial sediment in the nearshore area. Because as sea levels rose during the flandrian transgression they were pushed ashore from being deposited during sea level fall.

  they are then later modified by Long shore drift
• Emergent landforms are present when the sea level falls
• RAISED BEACHES 


  areas of former shore platforms are left at a higher level to that of the current sea level. they are found at a distance from the present coastline and usually only obtain fine sediment from alluvial erosion
• An example of a raised beach is in the Isle of Portland in Devon which is 15m above sea level.
• ABANDONDED CLIFFS 


  Cliffs which no longer interact with marine processes as the sea has retreated. some contain landforms such as ashes caves and stacks.
• MARINE TERRACES 


  Larger scaled landforms compared to raised beaches found at the base of relic cliffs . they don't have cliffs above them but their formation is the same as a raised beach with marine erosion and despition and the the retreat of the sea