What is a glacier? Alpine vs. continental glaciers?

Why study glaciers?

• presently covers 10% of land surface (Antarctica, Greenland, Iceland, Svalbard, Alaska, Himalayas, Alps, Southern Andes).
• 2% of earth's water budget, 75% of freshwater budget.
• excellent climatic indicator.
• during recent Ice Age much more extensive and so there are many 'relict' landscapes, shaped by glaciers.
• in paleontology and anthropology history of glaciation and changing environments controlled migration routes.
• they are just fascinating and beautiful.

How are the rocks incorporated into the glacier?

• rockfalls onto the ice from surrounding rock walls.
• plucking of ricks from underneath the ice.
• abrasion of rock by sliding ice.

What are some of the potential causes of Ice Ages?

• extraterrestrial causes: many unknowns and possibilities.
• Milankovich cycles:
  • sun-earth distance cycles over 105,000 years.
  • 22-24.5 degrees over 41,000 years.
  • direction of tilt (precession of equinoxes) 26,000 year cycle.
  • all should influence how much solar energy the earth is getting and thus influence our climate.
• terrestrial causes:
  • on long term: position of continents.
  • pulses of volcanic activity.
  • positive feedback cycle: albedo of snow is 70%, while that of normal ground is 20%.
• are we in or out of an Ice Age?

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