History of the Earth

History of the Earth - of life First Definite Signs of Life...

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History of the Earth a. Origin: remember the Nebular Hypothesis b. Age of the Earth – 4.6 billion years c. The Hadean Eon – first eon, Period between formation of the earth and the oldest rocks. (no rocks represented to the earth) a. Earth undergoes Melting and Differentiation 1. Continental Curst – Lighter % thicker Moho = Crust-mantle boundary Oldest Rock – acasra gneiss (NW Canada) 3.96 billion years Oldest Mineral – 4.404 billion year old (Zircon) Early Atmosphere and Ocean Volcanic gases: H20 – water (river, ocean) – H20 (steam) water (liquid) So2 – Sulfur dioxide Co2 – Carbon dioxide No2 – Nitrogen dioxide atmosphere Earth consists of 80% nitrogen Oceans existed by 3.8 billion years ago (age of oldest sedimentary rock) S gypsum CASO4 C limestone CACO3 N Atmosphere nitrogen gas First signs of Life The oldest sedimentary rocks (3.8 BILLION YEARS) have “chemical signatures”
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Unformatted text preview: of life First Definite Signs of Life Stromatolites – Oldest fossils (fossil algae filaments), 3.5 Billion Years Old Fossils A Grain of Pyrite (Fools Gold) Found in Ancient South African Rocks The oxygen revolution –-Algae produce oxygen-By 2 billion years ago, oxygen levels are up and as a -RESULT: GLOBAL SEDIMENTARY IRON FORMATIONS OF BIFS The Phanerozoic Eon (545 Million years ago – 2009 A.D.) Paleozoic Mesozoic and Cenozoic Eras-Breakup of early supercontinent-Cambrian “Explosion” of life-Animals develop teeth, shells Paleozoic-Early Paleozoic – marine organisms rule o Ex: Trilobites, corals, sponges o Everything was in sea, nothing on land-Later Paleozoic – o Fish and land plants (ferns) o Great coal beds o Some mountain building o Pangaea forms-End of Paleozoic – great extinction (96% extinct) Alfred Wegener-Father of the Continental Drift Hypothesis-Proposed idea of PANGAEA splitting into continents-Weatherman...
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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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History of the Earth - of life First Definite Signs of Life...

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