Enquiry question three Flashcards
What factors affect the rate of glacial erosion/movement
- basal temperature
- ice thickness
- precipitation levels
- ice and slope gradient
- bedrock permeability
- rates of ablation
What are the four glacial processes?
1- Erosion:
The removal of material via plucking, abrasion, fracture and dilation
2- Entrainment
Small rock fragments are trapped (entrained) by basal ice freezing around them which pulls them along
3- Transport
Rock debris is transported on the surface (supraglacial) within the ice (englacical) and at the base (subglacial)
4- Deposition
Glacial till (sediment deposited by the glacier ice)
Fluvio-glacial debris is deposited by glacial meltwater
what does polycyclic and polygenetic mean
cy—> many successive advances during ice house conditions
ge—> retreats during greenhouse conditions
UPLAND EROSIONAL FEATURES
MACRO FEATURES
how is a corrie formed
snow accumulates in a nivation hollow
it stays there and builds up year after year
compresses to ice
freeze thaw weathering and plucking of the back wall causes it to steepen
abrasion helps to over deepen the bottom
eventually the ice melts - creating the potential for a tarn/lake depending on rock type
what the feature called when two corries form side by side
an Arête
what is a pyramidal peak
they form when three or more cirques erode a mountain
what is a truncated spur?
pre glacial interlocking spurs are eroded by the glacier through plucking and abrasion
they are eroded, cutting off the spurs and creating a truncated spur
what is a u shaped valley/ a glacial trough
they occur where the glacier has carved through a pre glacial mountain valley (v shaped)
plucking and abrasion occur
this widens and deepens it
what are hanging valleys?
they occur when a smaller glacier joins the main glacier which is deeper and wider
at it retreats it leaves a large trough with many hanging valleys along the side
these can have waterfalls on them
e.g Little Langdale
what are ribbon lakes?
de glaciation water fills hollows within the glacial trough (which is deeper as the glacier can more easily erode the rock)
this is often sat on impermeable ground
these hollows are usually found within a change of geology
