Glaciation Presentation. Alan Doherty Linlithgow Academy

Glaciation Presentation

Alan Doherty Linlithgow Academy

Climate Change is not new!

From “Glaciers” by John Gordon

Colin Baxter Publications, 2001

Interglacial periods

Glacial periods

From “Glaciers” by John Gordon

Colin Baxter Publications, 2001

Snow collects in hollows• Snow builds up during the winter

(accumulation) and melts during the summer (ablation)

• If accumulation is greater than ablation the snow builds up in layers

• Pressure gradually turns the snow into ice

• When the critical mass of ice is reached, the ice begins to move downhill

• A glacier is born!

Snowflakes are compressed and squeezed into ice crystals

n.b. the colour changes from white to blue!

How does ice flow?

With difficulty!

GLACIATION

2. THE SNOW COMPACTS INTO ICE

3. THE ICE “FLOWS” DOWN THE MOUNTAINSIDE

4. THE GLACIER PUSHES FORWARD AND MELTS BACK

1.SNOW BUILDS UP IN HOLLOWS IN THE HILLSIDE

Valley Glaciers

Denali, in Alaska

nasa

Ice Sheets

From “Earth from Above” by Yann Arthus-Bertrand

• If the ice covers the whole area then the mountain tops are rounded e.g. Scotland

• If the mountain tops remain above the ice then frost action makes them “jaggy”. e.g.the Alps

Past and Present Ice Limits

From “Earth Story”

By Lamb and Sington

GLACIATIONGLACIERS ERODE

TRANSPORT

and DEPOSIT

Glacial Erosion

Glaciers erode in two ways

• Abrasion - this occurs when stones embedded in the bottom of the glacier scrape across the ground

• Plucking - this occurs when the bottom layer of ice freezes on to the ground when the ice is stationary. When the glacier begins to move, bedrock material may be torn from the ground.

Glacial Erosion

Cirque = Corrie = Cwm

From “A2 Geography for AQA specification A” by Bowen, A & Pallister, J. Reprinted by permission of Harcourt Education

Aretes or sharp ridges

corrie corrie

tributary glacier

main glacier

arete

A corrie is a hollow in the hillside

Corrie or cirque

Lochan or tarn

arete

Mountain top

End moraine

Aretes and pyramidal peaks

Pyramidal peak

Arete ridge

U-shaped valley

U-shaped valley

Hanging valley

Misfit stream

Ribbon Lake

Transportation

Material which is carried along by the ice is called moraine.

Large stones which are dropped as the ice melts are called erratics.

Transportation

Transportation

From “A2 Geography for AQA specification A” by Bowen, A & Pallister, J. Reprinted by permission of Harcourt Education

Deposition

by ice:moraine

by water:fluvio-glacial

Deposition

by ice:moraine

(boulder clay)

by water:fluvio-glacial(sands & gravel)