✅🟢Glacial Landscapes In The UK Flashcards
What’s a glacier?
Landform of ice situated in a valley
Mass of ice moving very slowly down the valley
‘Tongue shape’
Feb by snow in cold mountain environment
Isolated rocks - erratic rocks
Snow accumulated and compresses to form ice
How does the glacier advance / retreat?
Based on the weather
Describe a glacial valley
U shaped
Straight steep sides
Truncated ‘cut off’ Spurs
Broad base
When did the last ice age in the UK occur?
18,000 years ago.
During this time, temperatures stayed low throughout the year and ice sheets and glaciers covered the north of the UK and other parts of Europe.
How do glaciers shape the land?
Through processes of: Erosion Weathering Transportation Deposition
What is abrasion?
Type of erosion:
As the glacier moves downhill, rocks that have been frozen into the base and sides of the glacier scrape the rock beneath like sandpaper, leaving scratches like striations.
What’s plucking?
Type of Erosion:
Backwall of the valley where it’s a bit steeper + any protruding rock
Rocks become frozen into the bottom and sides of the glacier. As the glacier moves downhill it ‘plucks’ the rocks frozen into the glacier from the ground.
What’s freeze thaw weathering?
Weathering
Water flows into cracks in the rock, then freezes and expands, widening the cracks. The ice thaws and the process repeats until the rock breaks apart.
What’s debris carried above glacier called?
Supraglacial material
What’s debris carried within glacier called?
Englacial material
What’s debris carried beneath glacier called?
Subglacial material
What’s basal slipping
Transportation
Occurs when the weight of the glacier causes pressure melting at its base creating a film of melt water that reduces basal friction and allows glacier to slide
What’s Internal deformation / creep
Transportation
Ice crystals move past eachother within the glacier. Central part of glacier is ‘plastic’ and softer
What’s rotational slipping?
Glacier in a hollow moves along a curved surface in a circular motion
What’s bulldozing?
Transportation
When the snout of a glacier melts and retreated and layer of sediment is left behind. When the glacier advances again it ‘pushes’ the material at the snout forwards
What causes ice to move at different speeds?
Steepness of the slope + angle - so gravity acts on the glacier speeding it up
The edges are subject to friction which uses energy slowing it down but the midfield / center doesn’t have this friction allowing it to move faster - differential rates of movement
What’s transverse crevasses?
Small cracks that cute across ice flow - evidence of movement
What a Corrie?
armchair-shaped hollow found on the side of a mountain. This is where a glacier forms.
How does a Corrie form?
Snow collects in preglacial hollows
Snow turns into ice and moves downhill
Freeze thaw weathering and plucking cut into the back wall making it steep and jagged
Abrasion underneath the glacier depends the floor to create a basin shape
A rock lip marks the place where deposition has occurred. (Ice thinners / slightly uphill so less energy)
When ice melts - water trapped by lip creating lake / tarn
What’s an arête?
narrow ridge of land that is created when two corries erode back towards each other
What’s a pyramidal peak?
three or more corries erode back towards each other, at the top of a mountain a pointed peak is left behind
What are truncated Spurs?
A rounded area of land at the edge of a U-shaped valley.
What is a glacial trough?
deep U-shaped valley formed by a glacier.
What’s a ribbon lake?
Long narrow lake found in glacial trough.
What are hanging valleys?
smaller valley which is located high above the main U-shaped valley.
What’s moraine?
material carried or moved by a glacier
What’s lateral moraine?
material deposited along both sides of the glacier.
Usually weathered material that has fallen from the valley sides above the glacier.
What’s medial moraine?
material deposited in the middle of the glacier.
Caused by lateral moraines of two glaciers when they meet.