17 terms

Eustatic, isostatic and tectonic sea level change

Position of sea level
this has changed relative to the land
Eustatic change
A global change in sea level resulting from an actual fall of rise in the level of the sea itself
Isostatic change
Local changes in sea level resulting from the land rising or falling relative to the sea
Former glacial valley drowned by rising sea levels
Raised beaches
Areas of former wave-cut platforms and their beaches which are at a level higher than the present
Former river valley drowned by rising sea levels
18000 years ago
Sea levels were on average 110 metres below current levels during the last glacial maximum period
Colder climates
Cause increasing precipitation to fall as snow which eventually turns into glaciers, helps to lower sea level
Sea levels fall
This is because the snow and ice act as a store for water so the water does not return to the sea. This causes sea levels to fall which affects the whole planet
Weight of ice
Causes the land surface to sink. This only affects some coastlines and to a varying degree
Melting ice
Causes the replenishment of the main stores of water sea levels rise worldwide
Submergent features
Water floods the lower parts of the land to produce these. Examples include rias and fjords
Isostatic readjustment
As ice is removed from some land areas they begin to move back to their previous position
Emergent features
If the isostatic movement is faster than the eustatic then these are created. Examples include raised beaches
Britain in the present day
The southeast is currently sinking while the northwest is rising
Land bridges
These were still present across western Europe from 18000 to 10000 years ago after sea level rise began
Thermal expansion of the sea
Warming causes water to expand, causing sea level to rise