Glacial Landforms 1.Alpine erosional landforms 2.Alpine depositional landforms 3.Continental glacial landforms (erosional and depositional

Alpine Glacial Erosional Landforms

cirque

Tarn rock bound lake

Tarn (looking down)

horn

Horns have cirques on all sides (Mitre Peak, New Zealand)

U-shaped glacial trough from 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 on up side

Direction of Ice Flow

Glacial Grooves

Plucking refreezing around rock

Plucking refreeze and pull out

Alpine Depositional Landforms Boulders,Cobble Sand, 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 Zone Ablation Zone tarn in cirque lateral moraine Lateral moraines – evidence when the 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

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 Rockies Eurasian ice sheet: northern Europe Classroom Resource: Little Change in Antarctica

Biggest Changes Laurentide ice sheet: eastern N Am. Cordilleran ice sheet: Canadian Rockies Eurasian ice sheet: northern Europe

Wisconsin – 20 ka

On the ocean side …icebergs carried glacial sediment into the Atlantic Very cold & wet pulses

Gulf Stream further south – so northern Europe froze Heinrich events - Very cold & wet pulses

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 er_physics.html Origin of Glaciation ation_origins.html Glacial Landforms Resulting from Erosion and Deposition al_landforms.html Examples of Deglaciation ciation.html