Sea Level Changes Flashcards
What are the two different types of sea level change?
Eustatic and Isostatic
Define eustatic sea level change
Caused by change in the volume of water in the sea or by a change in the shape of the sea basin. The effects are always global.
What are the main causes of eustatic sea level change?
An increase in temp causing melting of ice sheets which increases sea level and causes water to expand. A decrease in temp causes more precipitation to fall as snow which increases the amount of water stored in the glaciers which reduces sea level.
+ tectonic plates shifting
Define isostatic sea level change
Caused by vertical movements of the land relative to the sea. Any downward movement of land causes sea level to rise locally.
What are the main causes of isostatic sea level change.
Uplift or depression due to the accumulation or melting of ice sheets. Slow uplift of land can continue for the thousands of years after the weight of a retreating glacier is gone.
What effects do sea level changes have on coastal areas?
1) storms become more frequent and more intense meaning more damage to coastal ecosystems and settlements.
2) more flooding
3) submergence of low lying islands
4) changes in coastline
5) contamination of farmland
6) increased rate of erosion
What happens when sea level falls?
Coastlines of emergence:
1) raised beaches
2) reveals wave cut platforms
3) relict cliffs where the cliffs are taken over by vegetation.
Describe what a ria is and how it is formed?
Rias are formed where river valleys are partially submerged, they have a gentle slope and are wide and deep.
They are a coastline of submergence.
What is a fjord and describe how they form?
They are drowned glacial valleys and are straight and narrow with steep sides.
Describe Dalmatian coastlines?
In areas where valleys lie parallel to the coast an increase in sea level can form a Dalmatian coastline. When valleys ares flooded and he leave islands parallel to the coastline.
How is a raised beach formed?
When the fall in sea level leaves beaches above the high tide mark. Over time the beach is colonised and develops into soil.
How is a wave cut platform a landform of emergence?
When sea level drops it reveals wave cut platforms more than before.
Describe the formation of a relic cliff.
The cliff above raised beaches are no longer eroded by the sea so slowly get covered by vegetation and will be eroded by weathering.
Give an example of a raised beach and relict cliff.
Cardigan Bay, Wales.
Give an example of a ria.
Milford Haven in Southwales
