Glaciers Ch. 17 Flashcards
Glacier
thick mass of ice
formation
snow flakes, granular snow, firn, glacial ice
Occurs within the ice
• Under pressure, ice is plastic
Internal deformation
• Entire ice mass slipping
along the ground
BASAL SLIP
Acts like a hydraulic jack,
lifting ice to move over rock
MELT WATER
Zone of fracture
- Upper 50 metres
* Tension causes crevasses to form in brittle ice
surges
RAPID MOVEMENT
ice advances
if accumulation exceeds loss
Zone of accumulation
where the glacier forms
zone of ablation
where there is a net loss to the glacier
• Lower limit is the equilibrium line
Calving –
breaking off of large pieces of ice into water
abration
Rocks in ice acting like sandpaper
• Produces rock flour and glacial striations
plucking (hint base of glacier)
Lifting and transport of rock blocks (Erratics) at the base of the glacier
hanging valleys
ABOVE GLACIER
lacial trough (U shaped)
• Transformed by deepening,
widening & straightening
Cirque
Head of glacier
Tarn (hint: related to cirque)
Lake in a Cirque
arete
Sharp Ridge
horn
Pyramid Mt
spur
Triangular Cliff
Roche moutonnées
asymmetric bedrock knobs with steep sides indicating direction of ice movement
fjord
water-filled glacial trough along a coast
till
Material deposited directly by glacial ice
stratified
Sediments laid down by meltwater
