SG2A: How are glacial landforms developed? (Depositiional Landforms) Flashcards
(32 cards)
What is glacial moraine?
Is used to describe an accumulation of glacial till to form a ridge. The deposition can occur from an active glacier or the deposition from ablation till left by the melting of ice.
What are the 4 characteristics a glacial till has?
- Angular
- Unsorted
- No orientation
- Not stratified
What does unsorted mean?
A variety of class material, large fragments to small materials such as clay.
What does no orientation mean?
Material doesn’t show a clear pattern.
What does not stratified mean?
Shows no sign of layering (push moraines and drumlins are an exception).
What is stratification?
Layering within the sediment deposited. This is common if material is deposited by water as the heavier sediments would be deposited first and the finer particles last.
WHta is terminal moraine?
A ridge of till extending across a glacial trough.
What is recessional moraine?
A series of ridges running transversely across glacial trough.
What is push moraine?
Till which has been shunted up in to a mound.
Where do you find terminal, push and recessional moraine of a glacier?
At the snout.
What is lateral moraine?
A ridge of till running along the edge of a glacial valley.
Where would you find lateral moraine on a glacier?
She of the glacier.
How is terminal moraine formed?
Form when the snout of the glacier is stationary, so accumulation = ablation, for a period of time and a ridge of deposited material can form at the snout.
How is recessional moraine formed?
1) Form during a temporary still-stand in retreat
2) The temporary pauses are rarely pro-longed, so recessional more rarely exceeds 100m in height.
How is push moraine formed?
1) The glacier advances due to positive mass balance
2) Reworks previously deposited till and bulldozes it forward to form a new ridge of till further down the valley during times of temporary stand still.
3) This material will show orientation
4) Steeper ice contact slope than other end moraines.
How is lateral moraine formed?
1) The material accumulates on top of the glacier having been weathered from the exposed valley sides.
2) As the glacier melts/retreats the material sinks through the ice to the ground and is deposited.
How is medial moraine formed?
Formed by two lateral moraines merging when a tributary glacier meets the main glacier.
An example of Terminal moraine??
The Franz josef glacier in New Zealand reaches 430m in height.
What is a till sheet?
Extensive flat plain of unstratified drift.
How is a till sheet formed?
they form when large quantities of this till were deposited by the thinning ice sheet.
An example of a till sheet?
East Anglia
What is a drumlin?
A streamlined hill which is composed of subglacial sediment.
What is the size of a drumlin?
vary up to 1km long, unto 500m
Where are drumlins found?
in lowland areas close to mountains.
