The changing cryosphere

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Cryosphere- Includes ice sheets, glaciers etc.

Large rocks buried in fine-grained soils- unlike the local bedrock- from 1000's km away- erratics

Louis Agassiz used Uniformitarianism. - Glaciers are able to carry huge boulders across long distances. They could explain the erratics. Proposed: an ice age had frozen Europe- ice sheets must have covered the land. 

Glaciers

  • Thick masses of recrystallized ice- last all year long + flow via gravity. 100's-1000's km thick. 
  • Current coverage= 10% of Earth but during ice ages- cover 30%.
  • Most recent ice age- 11,000 years ago
  • Snow-accumulates- compression-air expelled-pressure-melting-recrystallisation-granular firn-firn transforms-interlocking crystals=ice. 
  • Conditions- cold local climate (either polar or alpine); snowfall>melting; little removal of snow by wind etc.
  • Mountain glaciers, ice caps, ice sheets

Mountain glaciers: Cirque glaciers (mountain top bowls); Valley glaciers; ice caps on peaks and ridges; Piedmont glaciers spread out at the end of the valley. 

Ice caps: Cover mountain ranges

Ice sheets/continental glaciers: Cover continents: Greenland, Antarctic East. Antarctica West. West sits on the seabed-potentially more unstable:vulnerable to sea temperature increases, East would raise sea level by 65m if it were to melt. Greenland and West hold about 5m sealevel. 

Ice in the sea: Tidewater glacirs-valley glaciers entering the sea; Ice shelves- continental glaciers entering the sea; Sea ice- nonglacial ice formed…

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