February 16 - limestone N atmosphere First Signs of...

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Hadean - Heating episode, lighter material goes to surface and heavier material turns to 2 kinds of crust, mantle, core - Crust o Continental – lighter and thicker o Heavier (Ocean Crust) – denser and thicker Moho = crust-mantle boundary - Oldest Rock – 3.96 billion (let’s call it 4) o Acasta Gneiss – Canada - Oldest Mineral – 4.404 billion year old Zircon (have some uranium in them, and overtime the lead decayed – determine the age) - Early Atmosphere and Ocean o Volcanic gases: H20—dihydrogen oxide (water o So2- ______ o Co2-carbon o No2- nitrogen o H20 (steam) water (liquid) Oceans existed by 3.8 billion years ago (age of oldest sedimentaery rock) S gypsum C
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Unformatted text preview: limestone N atmosphere First Signs of Life-The oldest sedimentary rocks (3.8 billion) have ‘chemical signatures’ of life? o Have carbon in it to show it was once apart of an organism-Stromatolites – oldest fossils (fossil algae filantes) o 3.5 billion years old -Other late Precambrian life o Left imprints in rocks, trace fossils, not the organism itself The Phanerozoic Eon (545 Ma-2009 AD) Paleozoic Mesozoic and Cenozoic Eras-Breakup of early supercontinent-Cambian “Explosion” of life-Animals develop teeth? – shells Later Paleo-Fish and land plants -Ferns Alfred Wegener-The Continental Drift Hypothesis...
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This note was uploaded on 09/09/2009 for the course GEO 301 taught by Professor Long during the Spring '07 term at University of Texas.

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February 16 - limestone N atmosphere First Signs of...

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