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Preview of Deglaciation

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Unit 1.4- De-glaciation
Involves the post glacial modification of glacial landforms
Periglacial processes/landforms
Sea level change
temperate Post glacial processes/landforms
How sea level change has modified glacial landforms
Eustatic- Related to the growth and decay of ice sheets and glaciers-
When glaciers and ice sheets form water transfers from sees onto the land in the form of ice
and snow leading to a fall in sea levels. This likewise happens in the opposite direction with
sea level rises in interglacial periods
Isostatic - Related to the depression of land by ice mass
During glacial periods Ice sheets and glaciers develop and the land beneath is depressed.
These are isostatic depressions
This leads to a relevant rise in sea levels
During interglacials the ice melt and pressure is removed from the land leading to isostatic
recovery/rebound. This leads to a relative fall in sea levels
The actual change in sea level relative to the land depends on the balance between isostatic
change and Eustatic change.
Tectonic processes can also lead to sea level change
The lower sections of glacial troughs are flooded by a rise in sea levels.
Examples include sogne Fjord in Norway
The point between the end of the valley and the start of the sea which is flooded is either
called a threshold or a sill. Water within the valley is less deep
In Scotland they are called Lochs
Other sea level change landforms
Paired river terraces (Rejuvenation terraces)- When sea level falls the energy which a river
has for vertical erosion increases and so the river cuts down through part of its floodplain
leaving the remains of the floodplain at a higher level forming the paired river terraces. The
processes of increased power of erosion by a fall in sea level is called rejuvenation. The river
conwy in North Wales is an example


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