Geol30_08_Lecture_13b

E high latitudes north pole south pole occur at high

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Unformatted text preview: Pole South Pole Occur at high latitudes (Antarctica, Greenland) and also high altitudes (Andes, Himalayas, etc.) Thus, usually limited to these cooler areas 4 2/19/2008 But, a few glaciations were really globally extensive There are times when glaciers occurred i ( near) Th ti h l i d in (or ) equatorial regions at sea-level: sea-level: ~ 710 Ma ~ 635 Ma ~ 585 Ma (less in intensity/extent) These have been called "Snowball Earth" events Snowball Earth?! 5 2/19/2008 Snowball Earth IceIce-covered ocean down to Equator ( hard snowball) (= These extreme ice age may have lasted for millions of years shutdown of photosynthesis shutdown of hydrologic cycle PostPost-Snowball Earth also climatically harsh (very warm) A "freeze-fry, double-whammy" (p Prof. Stan Awramik) "freeze- y, doubley (per ) Implication: Implication: would lead to a mass extinction Let's look at what we know...and what paleontology can tell us... N.B., N.B., In this class/lecture, we'll focus on the reconstruction. More details...
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This document was uploaded on 06/04/2008.

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