Glaciation Flashcards
(18 cards)
Nevé
Half way stage between snow & ice (granular)
Like a slush puppy
Firn
More ice crystals than nevé
Gets compacted to for glacier
Glacier ice formation
Snowflake ➡️ granular snow (nevé) ➡️ firn ➡️ glacier
How do glaciers form
When snow remains in the same place all year round, year after year. It compresses crystalizing snow (nevé), grains get larger and larger squeezing the air out (firn) continued compression turns into glacier ice
How do glaciers move
Gravity pulls down slowly
Due to weight and pressure of ice above lower layers can melt producing melt water
This adds lubrication helping glacier slide down
KNOWN AS BASAL SLIDING
What causes glaciers to grow
More snow being added
Zone of accumulation
What causes glaciers to shrink
When temperatures warm up
Water evaperates or flows out from snout
Zone of ablation
Glacier erosion processes
Plucking
Abration
Freeze-thaw
Plucking
When ice freezes onto rocks it’s moving over and rips them out
Creates jagged surface
Abration
Carries rocks which scrape and scour the surface
Like sandpaper
Striations
Large scrapes on rock surface from abration
Freeze thaw
Water fills cracks during the day and freezes over night expanding by 9%. This repeats and weakens the rock and pieces break off
Scree slopes
Slope of rubble created when glacier melts
Formation of Corries
- Snow collects I’m North facing slopes (greater protection from sun)
- Snow builds up over years (nevé)
- Snow compacts turning into glacier ice
- Ice moves down hill, rotating due to gravity
- Plucking on back wall making steeper
- Abration deepens the hollow
- Freeze thaw at top makes jagged
- Rock lip, marks place of less erosion
- Ice melts and some water my be trapped and create a small loch
Arête
When 2 Corries are back to back creating a knife edged ridge
Cairngorms
Pyramidal peak
When 3 or more Corries are back to back
The cuillins of Skye
U-shaped valley
Formed when a glacier moves downhill down a V shaped valley.
Plucking and abrasion erode sides making U shaped valley
Once ice melted rivers flow through them again but too small the the wide valley so called MISFIT STREAMS
Ribbon loch
Abration on the valley floor when bands of soft and hard rock result in the soft rock being eroded resulting in a dip. Once ice melted the water fills the dip
Or glacier pushes rocks and pebbles at the front and once ice melts water can be water can be stopped by the rocks (makeshift damn)
Highlands
