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Glaciers

Glaciers . 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)

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Glaciers

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  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. Abrasion Polish Striations Chatter Marks Crescentic Gouges Bedrock Scour Deposition Till Outwash Varved Clays Meltwater Erosion Results of Glaciation

  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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