Sea level change Flashcards
What is Eustatic change
A global change in sea level resulting from an actual rise or fall in the level of the sea itself.
What is a isostatic change
Local change in sea level resulting from the land rising or falling relative to the sea
Causes of Eustatic change
-Thermal expansion/contraction of sea
-Ice accumulation on land-sea level fall
-Ice ablation-sea level rise
Causes of Isostatic change
-Tectonic movement.
-Isostatic rebound
Sequence of sea level change
1-As climate begins to get colder, increasing amount of ppt falls as snow. Eventually, this snow turns into glacier ice. Snow and ice act as a store of water. Sea level falls. Eustatic fall.
2- The weight of Ice causes the land surface to sink. Isostatic fall so relative sea level rise.
3- The climate begins to get warmer. Eventually the ice masses on the land begin to melt. Eustatic sea level rise.
4- As the ice is removed, land rebounds, isostatic re adjustment
Examples of sea level change due to tectonic activity
1) The uplift of mountain ranges and coastal land at destructive plate margins that resulted in a relative fall in sea level.
What is Fjord
A drowned glacial valley. U shaped cross section with hanging valleys on either side. Straight. Shallower section at the end called threshold, where the ice exited the valley and floated into sea.
What is a Rias
A flooded river valley, dendritic pattern. e.g Kingsbridge estuary Devon. - relative sea level rise due to eustatic rise.
-Isostatic depression as Scotland rises, re bounding
What sea level rise is predicted if we dop not change our ways
4m
Fairbourne Wales
Predicted to flood in 25 years time. 850 people will be displaced and become UK first climate refugees.
What are emergent features
Result of relative sea level fall
What are raised beaches
Former WCP which is now raised above sea level.
e.g Kings cave Scotland
What are Submergent features
Result from relative sea level rise
Example of submergent feature
Dalmatian coast- Islands running parallel to the coast. Formed from river valleys running parallel to the sea, which were then flooded by the sea.
