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!