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Glaciers

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Glaciers are flowing streams of ice ... Greenland Ice Cap. Antarctic Ice Cap. Antarctic Subglacial Lakes. Lake Vostok. Take-Away Points ... – PowerPoint PPT presentation

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Title: Glaciers


1
Glaciers
2
Take-Away Points
  • Glaciers are flowing streams of ice
  • Glaciers have a zone of accumulation where
    snowfall exceeds losses (ablation)
  • Accumulation can be due to high altitude
    (mountain glaciers) or cold climate (continental
    glaciers)
  • Glaciers have a zone of ablation where losses
    exceed snowfall
  • Glaciers are governed by a balance of snowfall,
    ice flow, and ablation
  • Glaciers retreat by melting back, not by
    retracting
  • Glaciers produce distinctive landforms and small
    scale features

3
Glacier a Flowing Stream of Ice
  • Mountain
  • Continental (Greenland, Antarctica)

4
Snowfall vs Melting Evaporation (Ablation)
  • Zone of Accumulation
  • Snowfall Exceeds Melting Evaporation
  • Excess Snow Turns to Ice Flows Out
  • Zone of Melting or Ablation
  • Melting Evaporation Exceeds Snowfall
  • Melting Excess Made up by Ice Flowing in
  • Terminus of Glacier
  • Snowfall Inflow Melting Evaporation
    (Ablation)

5
Anatomy of a Glacier
6
A Typical Glacial Advance and Retreat
7
As long as Accumulation Ablation, the Glacier
Front Remains Fixed
8
If Accumulation Exceeds Ablation, the Glacier
Advances
9
If Ablation Exceeds Accumulation, the Glacier
Retreats
10
Eventually, Material Trapped in the Ice Reaches
the Terminus
11
A Typical Glacial Advance and Retreat
12
Results of Glaciation
  • Abrasion
  • Polish
  • Striations
  • Chatter Marks
  • Crescentic Gouges
  • Bedrock Scour
  • Deposition
  • Till
  • Outwash
  • Varved Clays
  • Meltwater Erosion

13
Mountain Glacier Landforms
14
Continental Glacier Landforms
15
Greenland Ice Cap
16
Antarctic Ice Cap
17
Antarctic Subglacial Lakes
18
Lake Vostok
19
Take-Away Points
  • Glaciers are flowing streams of ice
  • Glaciers have a zone of accumulation where
    snowfall exceeds losses (ablation)
  • Accumulation can be due to high altitude
    (mountain glaciers) or cold climate (continental
    glaciers)
  • Glaciers have a zone of ablation where losses
    exceed snowfall
  • Glaciers are governed by a balance of snowfall,
    ice flow, and ablation
  • Glaciers retreat by melting back, not by
    retracting
  • Glaciers produce distinctive landforms and small
    scale features
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