Glacial Landforms and Processes: Ice Ages, Erosion, and Dune Formation
A long period of colder global climate during which continental ice shee
What's an ice age?
expand significantly.
A large, moving mass of ice that forms from the accumulation and
What's a glacier?
compaction of snow.
The elevation above which snow persists year-round and does not melt
Define snowline.
completely in summer.
A glacier that forms in mountain valleys.
What's a valley glacier? Found in mountainous regions (Alps, Rockies, Himalayas).
Moves downhill due to gravity, flowing like a slow river of ice.
A massive glacier that covers continental-sized areas (>50,000 km²).
What's an ice sheet? Found in Antarctica and Greenland today.
Spreads outward from a thick central accumulation zone.
How do glaciers flow? occuring below Plastic flow - internal deformation inside the ice, occurring below ~50 m
-50 depth.
How do glaciers flow? pt2 Basal slip - the glacier slides over bedrock on a thin layer of meltwater.
The upper 50 meters of a glacier.
What's the zone of fracture? Ice here is brittle, not plastic.
Features crevasses—deep cracks formed when the brittle ice is stretched
, Glacial Landforms and Processes: Ice Ages, Erosion, and Dune Formation
The balance between:
What is the budget of a glacier? Accumulation (snow added)
Ablation (loss from melting, sublimation, calving)
Positive budget → glacier advances, foot moves forward.
how does glacier budget affect glacier
Negative budget → glacier retreats, foot moves backward.
movement:
Balanced budget → foot stays in the same place.
By calving—chunks of ice break off the end of a glacier or ice sheet that
How do icebergs form?
reaches the sea.
Plucking - glacier picks up rocks.
How do glaciers erode the landscape?
Abrasion - dragged rocks grind and polish bedrock.
Ice thickness
Four factors controlling rate of glacial Ice speed
erosion: Bedrock resistance
Amount of debris in the ice
A long period of colder global climate during which continental ice shee
What's an ice age?
expand significantly.
A large, moving mass of ice that forms from the accumulation and
What's a glacier?
compaction of snow.
The elevation above which snow persists year-round and does not melt
Define snowline.
completely in summer.
A glacier that forms in mountain valleys.
What's a valley glacier? Found in mountainous regions (Alps, Rockies, Himalayas).
Moves downhill due to gravity, flowing like a slow river of ice.
A massive glacier that covers continental-sized areas (>50,000 km²).
What's an ice sheet? Found in Antarctica and Greenland today.
Spreads outward from a thick central accumulation zone.
How do glaciers flow? occuring below Plastic flow - internal deformation inside the ice, occurring below ~50 m
-50 depth.
How do glaciers flow? pt2 Basal slip - the glacier slides over bedrock on a thin layer of meltwater.
The upper 50 meters of a glacier.
What's the zone of fracture? Ice here is brittle, not plastic.
Features crevasses—deep cracks formed when the brittle ice is stretched
, Glacial Landforms and Processes: Ice Ages, Erosion, and Dune Formation
The balance between:
What is the budget of a glacier? Accumulation (snow added)
Ablation (loss from melting, sublimation, calving)
Positive budget → glacier advances, foot moves forward.
how does glacier budget affect glacier
Negative budget → glacier retreats, foot moves backward.
movement:
Balanced budget → foot stays in the same place.
By calving—chunks of ice break off the end of a glacier or ice sheet that
How do icebergs form?
reaches the sea.
Plucking - glacier picks up rocks.
How do glaciers erode the landscape?
Abrasion - dragged rocks grind and polish bedrock.
Ice thickness
Four factors controlling rate of glacial Ice speed
erosion: Bedrock resistance
Amount of debris in the ice
