GLACIATIONGLACIATION
About 15 million square kilometres of the earth’s surface are currently covered with glaciers
Continental ice sheets
Two Types of GlaciersTwo Types of Glaciers
• Continental:Continental: found at high found at high LATITUDES ex. Greenland, LATITUDES ex. Greenland, AntarcticaAntarctica
• Alpine:Alpine: found at high ALTITUDES found at high ALTITUDES ex. Western Cordilleraex. Western Cordillera
How GLACIERS FormHow GLACIERS Form
Two conditions need to be present:1 . Prolonged cold2 . Accumulation of snow
• Over time, the overlying layers of snowsnow compress thelower layers until it becomes ice.ice.
How Do Glaciers MOVE?How Do Glaciers MOVE?
• Glaciers move like a very thick liquid• Depending on the climate, a glacier can do
one of three things:– Advance– Stay Stationary– Retreat
Mass Balance: the rate of accumulation is balanced by the rate of ablation (melting)
How Do Glaciers Alter How Do Glaciers Alter the Landscape?the Landscape?
• Glaciers leave evidence on the landscape in the form of erosional features:
–Striations–U-shaped Valleys
–Spillways–Misfit Streams
Depositional FeaturesDepositional Features
1. Ice 1. Ice DepositsDeposits– Till – Moraines– Drumlins– Erratics
2. Meltwater 2. Meltwater DepositsDeposits– Eskers– Outwash plains
A Moraine
Oak Ridges Moraine
Spillway with a Mistfit stream
V- Shaped Valley
U-Shaped Valley
How ice alters the landscape
1. scraps or scours - like sandpaper - rocks are embedded into the bottom of the ice sheet and erode the bedrock as it flows
2. conveyor belt - embedded rocks are carried in the ice and deposited in the front as the glacier flows
3. plucking - ice freezes onto the rock and pulls or plucks it away as it flows
4. bulldozer - material is pushed along in front
The End!
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