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EARTH ORIGIN
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*
% of
Earth’s
History
78.0%
43.0%
9.3%
8.0%
3.8%
0.1%
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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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QuickT ime™ and a
P hoto CD Decompressor
needed to use this pict ure
Decay Products of U235
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Half-life = the time it takes
for half of the parent to decay into the daughter
QuickT ime™ and a
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P hoto CD Decompressor
needed to use this pict ure
Long half-life
Slow Processes
Short half-life
Fast Processes
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Earth’s Atmosphere Changes
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Life on Earth
• 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
Intertidal Algae
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Deep-sea
Black Smoker
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Life on Earth
• 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
• 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 bull’s 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
• 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