Glaciation Presentation. Alan Doherty Linlithgow Academy.
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Transcript of 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)