EARTH ORIGIN

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EARTH ORIGIN
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of Earths History

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If we compare the history of the earth to a trip
from College Station to Bush Intercontinental
(100 miles), the earliest human ancestors
would show up 117 yards from the entrance -
barely the length of a football field.
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Order of Planets from the Sun Sizes are
Relative Distances are not Accurate
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Order of Planets from the Sun Sizes are
Relative Distances are not Accurate
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Milky Way Galaxy
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Decay Products of U235
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Half-life the time it takes for half of the
parent to decay into the daughter
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Long half-life Slow Processes
Short half-life Fast Processes
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Earths Atmosphere Changes
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Life on Earth
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• Earliest known evidence of life was about 3.6
  billion years ago
• Early life may have started in the intertidal
  zone or at black smokers

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Intertidal Algae
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Deep-sea Black Smoker
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Life on Earth
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• Evidence suggest the composition of seawater has
  changed little over the last 600 million years
• Mass extinctions have occured over time. Why?

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Moon Craters
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Impact Craters in Canada
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Most impact craters would be in the oceans
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Life on Earth
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• Impacts from extraterrestrial bodies
• the latest big one was at the K/T boundary about
  66 million years ago
• it corresponds with the extinction of the
  dinosaurs
• in 1991 bulls eye pattern of gravity variations
  was detected off northern Yucatan (Chicxulub)
• the circle was 180 km in diameter

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Life on Earth
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• other more recent events include
• Winslow, Arizona about 50,000 years ago leaving a
  crater 4,000 wide and 750 deep - caused by an
  object 135 in diameter traveling at 12 miles a
  second with an explosive force of 15 megatons
• Tunguska, Siberia - 1908 - no crater, extensive
  damage, 10 megatons, site not visited for 20 years

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Meteorite Crater near Winslow, Arizona