EQ3 Flashcards
How did glacial erosional processes lead to the formation of corries
-Corries are depressions shaped like an arm chair
-In northern hemisphere they are found at higher latitudes facing east
This is beacause:
-Northern slopes receive less solar radiation, so the glaciers on those slopes have lasted much longer
-Western slopes face the sea and the relatively warmer winds blow from that direction increased ice melting
-Prevailing westerly winds cause snow to drift into east-facing slopes
Describe arêtes
-when two neighbouring glaciers cut back into each other on a mountainsides, they form a knife edged ridge between the two corries, known as an arête
-Found in present day landscapes (alps) and relict landscapes (lake district)
Process: plucking and abrasion on the back wall of the two corries means they erode backwards towards each other, creating a narrow ridge
Describe pyramidal peaks
pointed mountain peaks created by or more corries
Describe glacial troughs
- Characterised by steep-sided (mainly flat bottomed) and deep valley (often several hundred metres deep)
- Occurs when a pre-glacial river valley is eroded by a glacier by abrasion through basal-slip and plucking
- Predominantly straight due to the power and inflexibility of glaciers that erode them (v shaped valley eroded into u shaped)
Describe Ribbon Lakes
-Long narrow lake along the floor of a glacial trough
-Areas of increased plucking and abrasion by the valley glacier deepens parts of the valley floor as a result of either the confluence of glaciers or weaker rocks
-sometimes the rock forms behind a terminal moraine after glaciation
OXF: -weaker bedrock allowing increased vertical erosion, merging of a tributary glacier which can lead to glacial erosion of the valley floor due to the increased ice mass
-a narrowing of the valley and the resulting thicker ice which leads to increased vertical erosion
describe hanging valleys
Hanging valleys occur where a small side tributary glacier meets a larger main valley glacier
-During glacial phase, the surface elevation of the tributary and main valley glaciers is the same but, because the rate of erosion beneath the main valley glacier is greater, once the glacier have retreated the tributary valley can be left hanging many metres above, often with a waterfall plunging form the hanging valley to the main valley (e.g. Pistyll Rhaeadr in Berwyn mountains)
describe truncated spurs
-Unlike rivers that flow through interlocking spurs, the force of the glacier cuts off (truncates) spurs as it moves downhill leaving behind steep cliffs called truncated spurs
Process: abrasion is the dominant process in the formation of truncated spurs, plucking also takes place on the rock surfaces
-sub-aerial processes such as freeze thaw action and mass movement (rock falls) also act on the exposed rocky cliffs protruding above the ice
describe the formation of a roche mountonnee
1) As glacier moves over large obstacle, localised pressure decreases pmp which causes ice to melt
2) meltwater provides sufficient lubrication for glacier to move up slope, it smoothens the the stoss end through abrasion
3) as the end of the slope localised pressure decreases and the pmp increases, this causes the meltwater to re-freeze, this is called regeltion
4) the formation of ice causes plucking and abrasion giving the slope’s lee end a rough appearance
describe the formation of a crag and tail
(As a result of differential underying geology)
Formed when highly resistant rock (the crag) forces ice around it. protecting a deposition (known as tail) from erosion by abrasion and plucking (on the lee end)
describe knock and lochsn
a glacially scoured location, typically in lowland areas which have alternating rouchee mountonee and eroded hollows which often contain small lakes. these landscapes are determined by rock striations along features such as minor faults. they are most often dounf on rocks where alternate resistant and weakly jointed rocks allow for differental erosion
describe a drumlin
- looks like an overly ovular egg from birds eye view
- streamlined eliptical shape
- Up to 1500m long up to 50m wide up to 100m high
- steep stoss end shorter than lee slope
- long and less steep lee end
name some location where drumlins are found
England : eden valley, ribble valley, the shire plain
Scotland, Ireland, Sweden
What a group of drumlins called and what do they look like from birds eye view
called a swarm/drumlinfield
look like eggs in a basket
Are drumlins typically found isolated or in a collective
in a collective. Isolated drumlins are really rare
define equifinality
Where a theory of a process is uncertain. there are proposed mechanisms but no certainty as to which one is correct
