Geo2:Chapter 7

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Geo2:Chapter 7
2013-03-12 23:20:36

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  1. Geologic Time scale
    -subdivides earth’s history into unequal intervals of time based on distinctive fossil assemblages and globally important geologic events. 

    • 1. Oldest rocks: 5 billion years ago
    • 2. Oceans form: 4 billion years ago
    • 3. Photosynthesis and first life on earth: 3 billion years ago
    • 4. Atmosphere becomes oxygen-rich: 2 Billion years ago
    • 5. First multicellular life: 1 billion years ago
  2. Sediment
    • A collection of loosley packed unconsolidated particles. 
    • -Sources
    • 1. Weathering and erosion, or preexisting rocks
    • 2. Chemical precipitation from solution
  3. Fossils
    traces of plants or animals preserved in rock
  4. Law of superposition
    rocks at the bottom of the sequence are older than those lying above.
  5. Law of uniformitarianism
    geologic processes operating at present are the same processes that operated in the past
  6. Isotopes
    Varieties of an element containing different number of neutrons in their nuclei
  7. Elements
    • a substance that cannot be broken into other substances by ordinary chemical processes
    • -Total of 88 elements occur naturally in the earth's crust
  8. Holocene
    the post glacial epoch
  9. Alfred Wegener
    proposed continental drift hypothesis
  10. Pangea
    a supercontinent, which existed about 300 million years ago
  11. Paleomagnetism
    the study of earth's ancient magnetic field
  12. Collision of India and Asia
    -India hit Asia 14 million years ago
  13. Quaternary climate change
    • -the most recent 2.6 million years of Earth's history
    • -Fluctuations of temperature and sea level
  14. The Pleistocene Epoch
    • -The Ice Age
    • -Began about 1.6 million years ago
  15. Theory of ice ages
    During the cold climate periods large areas of the continents were covered by ice
  16. Pluvial lakes
    -formed at wetter climatic phases
  17. Ice age and sea level changes
    • -Eustatic sea level change
    • -sea level was lower than it is today
    • -exposed much more area on continents
  18. Sunda and Sahul
    • 1. Sunda
    • -Part of the continental shelf of Southeast Asia

    • 2. Sahul 
    • -Part of the Continental shelf of Australian continent
    • -Exposed as dryland during ice age
  19. Bering land bridge
    -Allowed human and animal migration from Asia to North America
  20. Desert packrats
    • -Middens are studied to reconstruct vegetation history 
    • -Middens pass from generation to generation
  21. Principles of Milankovitch theory
    • -Slow change of orbital parameters
    • 1. Eccentricity
    • 2. Tilt of axis rotation
    • 3. Precession of exinoxes