isostatic processes

• what is isostatic sea level change caused by?


  vertical movements of the land relative to the sea
• what does a depression of land cause sea level to do?

  rise

  whereas an uplift of land causes sea level to fall
• what scale do the effects of isostatic processes occur at and how quickly do they happen?

  they occur at a local scale and tale a long time to happen
• what is post-glacial adjustment?

  the large volume of ice that built up in the last ice age caused some crust to sink : this is isostatic subsidence
• what is isostatic rebound?

  the melting of ice sheets can slowly uplift the land as the lost weight of ice releases the downward pressure

  it can continue for thousands of years after the retreating glacier has gone, causing sea levels to slowly fall

  some areas of Scotland are still moving upwards up to 1.5mm a year
• abstraction of water?

  the subsidence of land due to shrinkage after abstraction of groundwater can cause the land to compact

  thus the surface can become flooded with seawater
• acretion?

  the acretion of sediment or the accumulation of ice can also add weight to the Earth's crust

  this makes it sink down and causes sea levels to rise
• tectonics?

  crustal processes such as one plate being forced beneath another at a plate margin can cause uplift of the crust which can either increase or decrease sea level