GEOLOGY1 - Chapter 1 • History of Universe Earth—only...

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Chapter 1 History of Universe: Earth—only planet w/ liquid water on surface Started w/ Big Bang 15 billion yrs ago Composition today: 75% H, 23% He, 2% other Expansion: galaxies are separating Matter distributed in clouds & within smaller clouds—nebulae Nebulae collapsed due to gravity Temperature raises… fusion 2H-He…star ignites Other elements made in core of stars by fusion Big stars end in a supernova explosion Our galaxy is the Milky Way Our sun: middle-sized, middle-aged star… 5 billion years ago Hydrogen (H) = 1 proton, 1 neutron Helium (He)= 2 protons, 2 neutrons o Solar System: Terrestrial Planets —inner planets (including Earth), heavy, rocky, few moons Jovian Planets —farther from sun, gaseous, large, low density, many moons Planetesimal accretion (terrestrial planets) Differentiated= divided into chemical layers In molten stage, heavier elements sink to form core (Fe, Ni), Silicates (Mg, Fe) form the mantle, and the crust is formed by the lightest elements (such as Al, Fe, Ca, K, Na & Mg) Out-gassing of atmosphere => precipitation => formation of oceans (also, comets) To “accrete”: to add material to make a bigger body o Life on Earth Oxygen was added to atmosphere only after life started photosynthesis (began w/ cyanobacteria…single cells w/ no nucleus) Life evolved around hydrothermal vents in the oceans Hard parts appeared 600 m.y.a. & fossils became frequent First vertebrates were fish… 500 m.y.a. (ray- & lobe-finned) 400 m.y.a. forest develops 350 m.ya. amphibians appear—problem: had to reproduce near water 250 m.y.a. reptiles were successful land conquerors Asteroid impact produces collapse of food chain, dust, fires, etc. Dinosaurs went extinct, but mammals prospered 3-4 m.y.a first hominids (ancestors of humans) in Rift Valley Oldest homo sapiens 35,00 (Europe) – 150,000 (Africa) yrs ago.
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Chapter 2 Scientific method: o Hypothesis—tentative explanation to be tested o Theory—highest rank of scientific knowledge, widely accepted explanation for observed phenomena Population: o Natural systems are in equilibrium… large disruptions may permanently change things o Earth’s carrying capacity—the number of individuals the earth can sustain in moderate health and comfort o Depletion of nat. resources… deforestation, starvation, social unrest… use alternative resources? Save energy? Plant trees? o Exponential pop. Growth rate o Doubling time ( 70/ growth rate % ) 117 yrs N. America Earth Materials: o Elements—cannot be changed into other by normal chem. means o Atom—minimum unit an element can be divided into, but still retain chemical properties o Isotopes—same element, different number of neutrons o Ions are charged atoms… Cation—lost e (+), Anion—gained e (-) o Octet rule: an atom tries to achieve a stable configuration w/ its outermost electron shell complete w/ 8 electrons (except first shell, with 2) o Bonding…covalent (share electrons), ionic (oppositely charged
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  • Fall '07
  • Wyld
  • Geology, Plate Tectonics, Sedimentary rocks, shell complete w/, large shadow zone, pressure w/ depth=, Oceanic lithosphere—Continental lithosphere

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