M_W_Chapter_19-3_Precambrian_glaciations_and_eukaryotic_life_-short_version

M_W_Chapter_19-3_Precambrian_glaciations_and_eukaryotic_life_-short_version

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Unformatted text preview: Precambrian Story: Changing climate, changing atmosphere, changing life on Earth Glaciations Early Proterozoic Gowganda (etc.) glaciations occurred somewhere in the time interval 2.4 to 2.2 Ga Late Proterozoic Varangian (etc.) glaciations 850 to 600 Ma Early Proterozoic aged ice sheet Gowganda Formation: Gowganda Formation: Early Proterozoic Early Proterozoic (about 2.2 Ga) Glaciers left (about 2.2 Ga) Glaciers left Deposits from Wyoming to Deposits from Wyoming to Hudson Bay Hudson Bay Extensive continental glaciation tillites, glacial striations, varves (Varangian glaciation) Late Proterozoic glaciation Snowball Earth? Snowball Earth suggested for both Early and Late Proterozoic glaciations, particularly the latter Entire planet smothered in ice for millions of years Tropics and equator signs of ice Temperatures around -40 C Warmed up at 600 Ma Life almost wiped out Complex life emerged Precambrian Story: Changing climate, changing atmosphere, changing life on Earth Banded Iron Formation and other clues to oxygen in the atmosphere both Early Proterozoic and Late Proterozoic glaciations coincide with BIFs Precambrian Story: Changing climate,...
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This note was uploaded on 05/18/2011 for the course GEOL 106 taught by Professor Richter during the Spring '08 term at University of Louisiana at Lafayette.

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M_W_Chapter_19-3_Precambrian_glaciations_and_eukaryotic_life_-short_version

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