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Causes and Formation of Glaciers

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Causes of Glaciers

There are many theories as to the cause of glaciations:

  • Milankovitch cycle – changes in incoming radiation due to changes in orbit, tilt and position in space.
  • Variations in sunspot activity
  • Changes in the amount of carbon dioxide in the atmosphere
  • Changes in the movement of the ocean currents
  • Periods of extreme volcanic activity which put huge amounts of ash into the atmosphere

Formation of Glaciers

  • During the onset of a glaciation, more and more precipitation falls as snow.
  • In addition, less and less snow melts each summer so that successive layers of snow gradually build up until there is a year-round snow cover in more and more places.
  • Fresh snowflakes trap much air and have a low density.
  • As snow becomes more compacted, the air is driven out and density increases.
  • Eventually, this process forms neve or firn (compacted snow).
  • After 20-40 years the firn will turn into glacial ice which contains little air and has a density of about 0.9.
  • Glacial ice can begin to flow downhill under the influence of gravity as a glacier.

This video looks at the formation of glaciers

glaciers

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