Glacial Landforms Flashcards
What is a corrie/cirque?
Arm chair shaped hollows with steep back walks and over depended basin
-usually found where there’s reduces heat so
more accumulation can occur
How do corries/cirques form?
Initially the hollow is likely to have been depended by nivation
- The accumulated snow turns to ice under pressure from the layers of snow,this weight causes the ice to begin to rotate and move
- as the ice pulls away from the back wall plucking occurs making it steeper
- the material supplies by blocking and ice frost shattering is used to abrade the floor of the hollow
- At the back wall the pulling away causes crevasses to form called BERGSCHUND
- the front is thinner ice and doesn’t proffer the same amount of abrasion,causing a rock lip to develop
What’s an arête?
When two or more corries erode back to back towards each other from opposing side it produces a knife edged ridge know as an arête
What’s a pyramidal peak?
When three or more corries erode back towards each other
How to valleys turn from V to U shaped?
As the glacier moves from upland to lowland areas they flown down pre existing river valleys which widens and straighten them
What are glacial troughs and how are they formed?
This is a u shaped valleys with steep sided values and flat bottoms
Formed by the erosion of v shaped valleys by glaciers and as the glacier eroded through the v shaped valley it it makes it deeper and wider
What are ribbon lakes and how are they formed?
Long thin lakes that collect from melt and rain water
They form when the water melts and fills the depressions that are caused by erosion of less resistant rock
What are hanging valleys and how are they formed?
Formed by tributary glaciers that erode the valley floor much less steeply as they are smaller than the main glacier
- so when the glaciers melts the valley gets left at a higher level than the glacial troughs formed by the main glacier
What are tarns?
Lakes that form in the corries after a glacier has retreated
What are valley steps and how are they formed?
Steps in the glacial trough
They’re formed when the glacier rise the valley floor more deeply as another glacier joins or there less resistant rock
What is a moraine?
The name for different formations of till deposited by a glacier as it melts
What are the three different types of moraine?
Lateral
Medial
terminal
What is a lateral moraine?
Till deposited where he sides of the glacier were
What is a medial moraine?
Till deposited in the centre of the valley where two glaciers converge (join together)
What’s a terminal moraine?
Till that builds up at the end of the glacier and is deposited as semicircular hillocks
