6.1: The distinctive landforms of glacial erosion Flashcards
What is the most important factor that effects the efficiency of a glaciers erosion?
the glacier itself - its size, which determines ice thickness and thermal regime
Which type of glacier erodes faster?
Warm based or cold based?
why is that?
- warm based
- meltwater and abandant debris facilitate abrasion
- regulation occurs (water melting under pressure and then refreezing)
- plucking
Name 3 factors that influence the rate of glacial erosion
- glaciers velocity across the bed
- ice thickness - so the power of the glacier to cause shattering
- rock debris - its quantity and shape
- whether freeze-thaw weathering is occurring
- the bedrock characteristics
erosion rates are most intense when glaciers are …? based, thick and …? moving
- warm based
- fast
Name the glacial erosional feature from its description.
An armchair-shaped hollow on a hillside above a glacial valley
What scale is it?
cirque
Macro
Name the glacial erosional feature from its formation
A pre-glacial hollow is enlarged by plucking and abrasion as ice moves in a rotational manner under gravity
cirque
Name the glacial erosional feature from its description
A narrow ridge between two cirques
What scale is it?
Arete
macro
Name the glacial erosional feature from its formation
As two cirques are enlarged back to back, the ridge between them becomes increasingly narrowed
Arete
Name the glacial erosional feature from its description
A sharp, pointed hilltop
What scale is it?
Pyramidal Peak
macro
Name the glacial erosional feature from its description
A steep-sided, flat-floored, straight valley
What scale is it?
Trough or U-shaped Valley
macro
Name the glacial erosional feature from its description
A steep and possibly rocky section of a side crop
What scale is it?
Truncated Spur
macro
Name the glacial erosional feature from its description
A small tributary valley high above the floor of trough often with a waterfall
What scale is it?
Hanging Valley
macro
Name the glacial erosional feature from its description
Asymmetrical bare rock outcrop with a gently side facing up-valley
What scale is it?
Roche moutonnee
meso
Name the glacial erosional feature from its description
Grooves on exposed rocks
What scale is it?
Striations
micro
Name the glacial erosional feature from its formation
As three or more cirques are enlarged the hilltop between them becomes increasingly sharp and pointed
Pyramidal Peak
Name the glacial eorsional feature from its formation
A pre-glacial river valley is widened and deepened by erosion from an advancing glacier
Trough or U shaped Valley
Name the glacial erosional feature from its formation
The pre-glacial interlocking spurs of the river valley are eroded by the much more powerful glacier
Truncated Spur
Name the glacial erosional feature from its formation
Tributary glaciers with small amounts of ice did not erode their valley floor as deeply as the main glacier and so are left at a higher altitude
Hanging Valley
Name the glacial erosional feature from its formation
As ice crosses a resistant rock outcrop, the increased pressure causes melting and basal sliding and the up-valley side is smoothed by abrasion. On the leeward side pressure is reduced, refreezing occurs and plucking takes place, causing a steep, jagged slope
Roche moutonnee
Name the glacial erosional feature from its formation
Abrasion by debris embedded in the base of the glacier as it passed over bare rock. They can indicate the direction of ice movement
Striations
Name the glacial erosional feature from its description
a long and deep, finger-shaped lake, usually found in a glacial trough
what sale is it?
Ribbon or finger lake
meso
Name the glacial erosional feature from its description
irregular chips and fractures in the rock
What scale is it?
Chatter marks
micro
Name the glacial erosional feature from its description
small rounded hills with no vegetation with small lakes
Knock and lochan landscape
Name the glacial erosional feature from its formation
The lochs are formed by overdeepening and the knocks are more resistant bedrock.
Knock and lochan landscape
Name the glacial erosional feature from its description
A landform consisting of a rock hill and tapering ridge
Crag-and-tail
Name the glacial erosional feature from its formation
This featured is formed when glacial ice is forced around a large and resistant rock obstacle, such as a voltaic plug, which protects the less-resistant material on the leeside causing the feature to taper into a tail in the down-glacier direction
Crag and tail
a famous example is that Edinburgh castle is built upon a crag and tail
Supraglacial refers to material…
on the surface of a glacier
Englacial refers to material…
dispersed throughout the interior of a glacier
Subglacial refers to material…
Debris which has been released from ice at the base of a glacier
Name the glacial erosional feature from its description
A rock of unspecified shape and size, transported a significant distance from its origin by a glacier or iceberg and deposited by melting of the ice
Give an example of where they are found and what they show
Erratic
erratic from Scandinavia have been found in boulder clay of the Northumberland, Durham and Yorkshires coasts the the Northeast of England - confirming the presence of the continental ice sheets from Scandinavia
Name the 4 main processes by which glaciers deposit material
- Lodgement
- Ablation
- Deformation
- Flow
Describe how glaciers deposit their material by lodgement
Lodgement occurs when the friction between the subglacial debris and the bed becomes greater than the drag of the ice moving over it.
It is commonly associated with glaciers carrying huge loads of debris and where the glacier is very slow moving, if not static
Describe how glaciers deposit their material by ablation
this process refers to debris being dumped as the glacier melts and thaws.
It can include supraglacial and englacial material, as well as subglacial material.
Describe how glaciers deposit their material by flow
occurs if high meltwater content causes the glacial debris to creep/slide or flow during deposition.
