Chapt02_OriginsOceanography

Chapt02_OriginsOceanography - Origins Origins Origin of the...

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Unformatted text preview: Origins Origins Origin of the Earth Origin • Big Bang – beginning of the expansion of the universe the • 10-20 billion years (Billion years -BY ) ago: 10-20 the Universe is born the • As the matter cool off forms atoms from As the original matter the • Most of it was H Galaxies and Stars Galaxies • Formation of solar system Formation • From gas cloud ( pre-solar nebula) 4.56 BY BY • Galaxy is an aggregation of stars, dust Galaxy and gas and • Milky way is our galaxy (f. 1.5) • Star – spheres of incandescent gases Formation of Planets Formation • Solar Nebulae was a rotating disk • Spun faster as it condensed and the Spun center became the protosun center • The other material became the planets • Planets including Earth, from Planets planetesimals (asteroid-sized) bodies complete 5 BY (f.1.11) complete Oceans Oceans • There are basically three possible sources for There • • • the water of the Oceans, it could have: the (1) separated out from the rocks that make up (1) the bulk of the earth; (2) arrived as part of a of water- rich meteorites, (2) or (3) arrived as part of of icy planetesimals he • tthe best model for the source of the oceans at • the moment is a combination of water derived from comets and water that was caught up in the rocky body of the earth as it formed rocky Most of the water was probably present Most originally as water trapped in clay minerals or as separate hydrogen (in hydrocarbons) and oxygen (in iron oxides), rather than as ice. • Liquid water and oceans have formed by Liquid 4.6 BY 4.6 • Oldest known rocks on Earth 4.0 BY Oldest • Earliest signs of life in oceans 3.85 BY Earliest Origin of Life Origin of Life • 1953 Stanley L. Miller, did the first experiment • designed to clarify the chemical reactions that occurred on the primitive earth. In the flask at the bottom, he created an "ocean" of water, which he heated, forcing water vapor to circulate through the apparatus. The flask at the top contained an "atmosphere" consisting of methane (CH4), ammonia (NH3), hydrogen (H2) and the circulating water vapor. • Next he exposed the gases to a continuous • • electrical discharge ("lightning"), causing the gases to interact. Water­soluble products of those reactions then passed through a condenser and dissolved in the mock ocean. The experiment yielded many amino acids and enabled Miller to explain how they had formed • • • Did life form in these experiments? NO Crucial compounds can be synthesized so easily • Biosynthesis is still speculative, but at this point we do not have a better explanation Multi-cellular organisms Multi-cellular • The oldest fossil, from Northern Australia, The are between 3.4-3.5 BY (f.1.18) are • Multi-cellular organism suddenly appear Multi-cellular about 600 MY about • Ice ages begin, hominids appear 2 MY Ice • modern Homo sapiens appears ~100,000 Homo sapiens Y ...
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