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ESC Pleistocene Glaciation Chapter


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Louis Agassiz
-19th century Swiss geologist
-Suggested that eupope and north america were covered by thick ice sheets in the recent geologic past.
Evidence for past continental scale ice sheets
Erratic boulders, Ground moraine found in northern parts of US and Europe, Glacial straiations on rocks, layers of till.
Erratic boulders
-large boulders transported by glacial ice.
-can be traced back to their source rock bodies, marking flow direction of ice sheets.
Milutin Milankovitch
-calculated the amount of sunlight each latitude received in every phase of earth's orbital variations.
-Pacemaker of the Ice ages
Milankovitch Theory
Ice ages occur when orbital variations cause the northern hemisphere to receive less sunshine in the summer. Predicted that ice ages would peak every 100,000 and 41000 years.
Axial tilt affect on solar radiation
When the tilt is decreased, polar regions receive less sunlight; when it is increased, polar regions receive more sunlight.
Positive feedback factors
-A changing albedo- increased snow on land
-Less evaporation-sea is less salty
-Biological processes that change CO2 concentration.
Pleistocene interglacials typically lasted how long?
10,000 years
The precent interglacial began how many years ago?
Little Ice Age
-1300'2-mid 1800's
-Montain glaciers advanced significantly.

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