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Glacial Landforms
1. Alpine erosional landforms2. Alpine depositional landforms3. Continental glacial landforms
(erosional and depositional
Alpine Glacial Erosional Landforms
cirque
cirque
Tarn
rock bound lake
Tarn (looking down)
horn
Horns havecirques onall sides (Mitre Peak, New Zealand)
U-shaped glacial troughfrom v-shaped river valley
Hanging Valley
Originally
After Ice Melts
Fjord
Iceland
Telluride
Snowbird – Little Ice Age Cirques
Glaciers smooth aretes and allow travel over these col passes
Melting from
Pressure: upside
Polishing onup side
Direction of
Ice Flow
Glacial Grooves
Pluckingrefreezing
around rock
Pluckingrefreezeand pullout
Alpine Depositional Landforms
Boulders,CobbleSand, Silt – where
does it come from?
Mass Wasting, avalanches onto glacier
Erosion along the bed of a glacier
Till – boulders down to clay deposited in contact with a glacier
Deposited in the Ablation Zone
Basic forms, after glacier ablates
Moraines – ridges of till
Lateral moraines – from avalanches on the sides of the glacier
Accumulation ZoneAblation Zone
tarn in cirquelateral moraine
Lateral moraines – evidence whenthe glacier is all gone of its extent
Lateral moraines – deposited in ablation zone
lateral moraines join end moraine
Glaciers are a conveyor belt and moraines are the ‘garbage dump’
animated gif that should play (don’t worry if it does not)
end or terminal moraine (shows maximum extent)
end moraine
end moraine
Recessional Moraine
Laterals join recessional/end moraine
end moraine
laterals come together as medial moraines
Only see medial moraines when glaciers are present (they are destroyed by meltwater streams)
Meltwater streams deposit outwash plains
Fox Glacier, New Zealand
Glacial Erratics – giant boulders left behind: Noah’s flood or ancient ice age?
Religion vs. Science
Continental Glacial Landforms
Biggest Changes (where see evidence)Laurentide ice sheet: eastern N Am.Cordilleran ice sheet: Canadian RockiesEurasian ice sheet: northern EuropeClassroom Resource: Little Change in Antarctica
Biggest Changes
Laurentide ice sheet: eastern N Am.Cordilleran ice sheet: Canadian RockiesEurasian ice sheet: northern Europe
Wisconsin – 20 ka
On the ocean side …icebergs carried glacial sediment into the
Atlantic
Very cold & wetpulses
Gulf Stream further south – so northern Europe froze
Heinrich events -Very cold & wetpulses
Under the Ice
Areas of Scour: rock ground down, plucked, and quarried producing lots of bare rock and lakes
Deep Valley Cutting: large troughs eroded by concentrated abrasion, quarrying and plucking
Areas of Little Erosion: where its so cold that all the pressure can’t melt the bottom ice, cold-based glaciers produce little movement and little erosion
Aerial Scouring: East Antarctica
Aerial Scouring: Ireland
Aerial Scouring: Finland and Newfoundland
Deep Valley
Cutting: Finger Lakes
Deep Scour
Long Island Terminal Moraine
Started with deep scouring, then got complicated
Each of these in turn
End Moraine: Greenland
End of Cordilleran Ice Sheet
Outwash
Till Plain(or ground moraine)
Drumlins
Oriented with flow
Drumlins in Patagonia
Perhaps formed under areas of fast moving ice
Kettle Lakes
Spectacular Outwash: Iceland
Online Resources
Glacier Physics
http://serc.carleton.edu/NAGTWorkshops/visualization/collections/glacier_physics.html
Origin of Glaciation
http://serc.carleton.edu/NAGTWorkshops/visualization/collections/glaciation_origins.html
Glacial Landforms Resulting from Erosion and Deposition
http://serc.carleton.edu/NAGTWorkshops/visualization/collections/glacial_landforms.html
Examples of Deglaciation
http://serc.carleton.edu/NAGTWorkshops/visualization/collections/deglaciation.html