Alpine Glaciers

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Alpine Glaciers

• Ice that flows down mountain valleys
• (e.g. in the Alps!)

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• Mont Blanc, near Chamonix, France - note the
  alpine glacier that flows to lower elevations,
  nearly reaching the main valley in which Chamonix
  lies

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Bergschrund at head of a glacier above Chamonix
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Mer de Glace above Chamonix - note ogives
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Rockfalls from the valley walls add debris to the
glaciers surface
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Glaciers are capable of carrying debris of almost
any size - from the fine particles embedded in
the ice in the foreground, to the huge angular
boulder in the background
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Landforms of Alpine Glaciation

• U-shaped valleys
• Cirques, Aretes, Horns
• Moraines
• Striations

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Mer de Glace

• An alpine glacier, whose flow is confined to a
  valley
• Such glaciers are very efficient at eroding their
  valleys, widening and deepening them into classic
  U-shaped valleys

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Fjord - a glacially eroded valley invaded by the
sea
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Cirques are high basins where alpine glaciers
originate
Horn
Arete
Cirque
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The Grand Teton (WY) is a classic horn - note
several small cirques that have eroded into the
mountain, leaving only a fairly narrow, jagged
peak.
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Iceberg Lake (Glacier National Park, MT) occupies
a cirque The sheer rock face at the back of the
cirque is an arete - a narrow ridge between two
cirques that have eroded back into the mountain
from opposite sides
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Portage Glacier (AK) - note lateral and medial
moraines
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Medial moraines form where glacial tributaries
merge
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End moraines form at the terminus of a glacier
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Cirques with small residual glaciers in the Lyman
Valley, WA Note the end moraines, built of
debris deposited by the glaciers when they
extended a bit further downslope during the
Little Ice Age (1550-1850)
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Glacial Abrasion

• Debris carried at the base of a glacier can
  smooth and scratch the bedrock it flows over -
  the scratches are called striations