Visualizing Physical Geography Copyright 2008 John Wiley and
Sons Publishers Inc. Chapter 14 Glacial Landforms and the Ice Age
Visualizing Physical Geography by Alan Strahler and Zeeya Merali
Slide 2 Visualizing Physical Geography Copyright 2008 John Wiley
and Sons Publishers Inc. Chapter Overview Glaciers Alpine Glaciers
Ice Sheets and Sea Ice The Ice Age Slide 3 Visualizing Physical
Geography Copyright 2008 John Wiley and Sons Publishers Inc.
Glaciers Glacier: large natural accumulation of land ice affected
by present or past flowage Glacial ice has shaped many landforms in
middle and high latitudes Glacial ice sheets affect global climate
Glaciers reflect sunlight Glacial ice affects global heat transport
Volume of glacial ice affects sea levels Large bodies of ice are
plastic because of pressure on ice at bottom of mass Large body of
ice can flow in response to gravity Ice on a slope can slide
downwards Ice sheet: large thick plate of glacial ice moving
outward in all directions Slide 4 Visualizing Physical Geography
Copyright 2008 John Wiley and Sons Publishers Inc. Glaciers Glacial
ice builds up when snowfall in winter exceeds snow melted in summer
Each annual layer of snow, melts, refreezes, forms ice Weight of
ice compresses the lower layers into hard crystalline ice When the
ice mass becomes thick enough, the lower layers flow plastically
Glacial ice forms where temperatures are low and snowfall is high
Alpine glacier: long, narrow mountain glacier occupying the floor
of a trough-like valley Slide 5 Visualizing Physical Geography
Copyright 2008 John Wiley and Sons Publishers Inc. Glaciers
Glaciers contain rock of all sizes Glaciers and ice sheets erode
and deposit great quantities of sediment Glacial abrasion: rock
fragments in a glacier scrape and grind the bedrock Plucking:
moving ice plucks loosened rock material and carries it away
Sediment is carried, then deposited when the ice melts Slide 6
Visualizing Physical Geography Copyright 2008 John Wiley and Sons
Publishers Inc. Alpine Glaciers Upper part of the glacier is
brittle Lower part is plastic Zone of accumulation: glacier is
growing Zone of ablation: glacier is evaporating/melting Alpine
glacier can slide downhill on meltwater and mud Rate of movement:
few centimeters/day to several meters/day Surge: rapid movement of
alpine glacier, up to 60 m/day for several months Slide 7
Visualizing Physical Geography Copyright 2008 John Wiley and Sons
Publishers Inc. Alpine Glaciers Landforms Made by Alpine Glaciers
Slide 8 Visualizing Physical Geography Copyright 2008 John Wiley
and Sons Publishers Inc. Alpine Glaciers Landforms Made by Alpine
Glaciers Slide 9 Visualizing Physical Geography Copyright 2008 John
Wiley and Sons Publishers Inc. Alpine Glaciers Landforms Made by
Alpine Glaciers Cirque: valley head enlarged and hollowed out by
glaciers, producing bowl-shaped valley Arte: sharp ridge formed
between two cirques Horn: steep-sided peak formed by glacial
erosion from three sides Col: natural pass or low notch in an arte
between opposed cirques Moraine: accumulation of rock debris
carried by an alpine glacier and deposited by the ice to become a
depositional landform Tarn: small lake occupying a rock basin in a
cirque Hanging valley: stream valley that has been truncated by
glacial erosion so as to appear in cross section in the upper wall
of a glacial trough Slide 10 Visualizing Physical Geography
Copyright 2008 John Wiley and Sons Publishers Inc. Alpine Glaciers
Landforms Made by Alpine Glaciers Slide 11 Visualizing Physical
Geography Copyright 2008 John Wiley and Sons Publishers Inc. Alpine
Glaciers Landforms Made by Alpine Glaciers Glacial trough: deep,
steep- sided rock trench formed by alpine glacier erosion Fiord:
narrow, deep ocean inlet partially filling a glacial trough Slide
12 Visualizing Physical Geography Copyright 2008 John Wiley and
Sons Publishers Inc. Ice Sheets and Sea Ice Ice Sheets of the
Present Antarctic Ice Sheet 13 million sq km 4000 m thick Greenland
Ice Sheet 1.7 million sq km 3000 m thick Slide 13 Visualizing
Physical Geography Copyright 2008 John Wiley and Sons Publishers
Inc. Ice Sheets and Sea Ice Sea Ice and Icebergs Sea Ice: floating
ice of the oceans formed by direct freezing of ocean water
Always
