SG4: How landforms in glaciated landscapes are influenced in post glacial periods? Flashcards
What does post glacial period mean?
The meltwater period.
What is a post glacial climate?
Glacial periods end when the global temperatures rise, then followers by shorter inter-glacials. In the post glacial period, temperatures often increase gradually.
What is glaciofluvial?
Describes the processes and landforms associated with the action of meltwater streams from glaciers during post glacial times.
What are the meltwater stream characteristics?
- Variable velocity
- Variable discharge
- Hydrostatic pressure.
What are glaciofluvial landforms developed by?
Deposition.
What are the proglacial features?
outwash plains
kettle lakes
What are the ice contact features?
Esker
Kames
What is an outwash plain?
A flat expanse of glaciofluvial sediment located in the proglacial area.
A description of an outwash plain?
- Flat gentle sloping
- Found in front of glacier snout
Name an example of an outwash plain?
Solheimajokull, Iceland 57km squared
How is an outwash plain formed?
Proglacial streams that are present as temperatures melt and the glacier beings to retreat up the valley transport a lot of sediment, but highly variable discharge allows for it to be deposited.
What is the subsequent modification of the outwatch plain?
- the advancing and retreating of this outwash plain causes more meltwater forming proglacial streams.
- Plant colonisation affects subsequent geomorphic processes on the outwash plain by weathering - causes biological weathering
- Over time plant colonisation is occurring on the exposed outwash plain.
What is an esker?
A long winding (sinuous) rice composed of stratified sand and gravel deposited by meltwater streams.
Description of an esker?
- Sinuous ridge of material
- Varies in height and length
- May be continuous or beaded
- Usually form parallel to valley sides along the valley floor.
Give an example of an esker?
Mosedale esker, Lake district.
How is an esker formed?
temperature rises so glacier begins to melt meaning discharge of meltwater streams and their sediment load increases. Eskers result from deposition of material carried by subglacial and englacial meltwater streams during the glacial period. Deposition occurs when pressure is released as meltwater from the glacier snout.
What is the subsequent modification of an esker?
- Plant colonisation has reduced the mass movement but also biological weathering can take place.
- New eskers still exposed to physical weathering so may cause slumping of the sides (mass movement).
What is a kame?
A hill or hummock of stratified sand and gravel laid down by a glacial meltwater.
Description of a kame?
a flat topped, steep sides hill of well sorted sand and gravel deposited by meltwater streams flowing into andice marginal lake or sea.
How is a kame formed?
As meltwater streams enter ice-marginal lakes, they lose energy because they are entering a static body of water. This means they deposit the material they are depositing.
What is the effect on climate change to Kames?
Warmer temperatures amounts to more melting equals more meltwater creating greater accumulation of outwatch material= more material to be deposited.
What is a kame terrace?
A ridge of material running along the edge of the valley.
An example of an kame terrace?
Kingsdale valley, Yorkshire Dales
How is a kame terrace formed?
Supraglacial streams form at the sides of the glacier as a result of friction due to the exposed valley sides heating up faster than the glacier. These streams form small troughs at the sides of the glacier and pick up and carry lateral moraine. The material is later deposited by meltwater streams in post glaciation between a glacier and a valley wall.
What is the effect on climate change to kame terraces?
Warmer temperatures = exposed valley sides heat up faster than the glacier ice= more melting along the edge of the glacier = more games exposed and of greater length.
