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GLACIATION

GLACIATION. GLACIERS. Definition a slowly moving mass or river of ice formed by the accumulation and compaction of snow on mountains or near the poles. GLACIERS.

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GLACIATION

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  1. GLACIATION

  2. GLACIERS • Definition • a slowly moving mass or river of ice formed by the accumulation and compaction of snow on mountains or near the poles

  3. GLACIERS • At any place on the land where more snow accumulates than is melted during the course of a year, the snow will gradually grow thicker. • As the snow piles up, the increasing weight of snow overlying the basal layers causes them to recrystallize, forming a solid mass of ice. • When the accumulating snow and ice become so thick that the pull of gravity causes the frozen mass to move, a glacier is born.

  4. HOW IS A GLACIER FORMED? • Ice crystals grow & join together to form solid sheets 90% air 50% air

  5. ALPINE GLACIER: • a glacier found in a mountain range • forms because of the continual snow build-up in mountainous areas

  6. ALPINE GLACIER

  7. ALPINE GLACIER

  8. Alpine Glaciers Make Land Rugged

  9. CONTINENTAL GLACIER • A continuous mass of unconfined ice, covering at least 50,000 square km • Most extensive at present as ‘ICE SHEETS’ covering Greenland and Antarctica

  10. Continental Glaciers Round the Landscape

  11. EROSIONAL FEATURES OF GLACIERS • Straitions

  12. Geological Survey of Newfoundland

  13. GLACIAL DEPOSITS • After eroding rock, glaciers leave “deposits” • Glacial Drift: refers to all sediments of glacial origin

  14. TILL • material that is deposited directly by the ice

  15. OUTWASH • sediments laid down by glacial melt water

  16. EROSIONAL FEATURES FINGER LAKES • glaciers gouge out a strip of land in a narrow channel often where a river valley once existed

  17. EROSIONAL FEATURES KETTLES • Are hollows formed when giant blocks of ice were buried in the till

  18. EROSIONAL FEATURES FJORDS • Flooded U-shaped valleys

  19. FJORDS

  20. EROSIONAL FEATURES CIRQUES • Circular hollows on the upper slopes of mountains where alpine glaciers originated

  21. EROSIONAL FEATURES ARETES • Ridges that are left when two cirques occur side by side

  22. ? horn ? cirque ? arete

  23. DEPOSTIONAL FEATURES ERRATICS • A large, isolated boulder left behind by a glacier

  24. ERRATIC

  25. ICE AGE • An extended period of sub-zero temperatures (10,000 years) where glaciers are found over large areas of land

  26. ICE AGE • Most recent Ice Age ended 12,000 years ago (Wisconsin Ice Age)

  27. GEOLOGIC TIMELINE

  28. GLOBAL DISTRIBUTION OF GLACIERS • Occupy 10% of Earth’s surface

  29. GREENLAND GLACIER

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