Sci. 3-5

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Sci. 3-5 Times Marches On Pages 73-77
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• The history of the Earth is recorded in rock
  layers
• 1) Earth is about 4.6 billion years old.

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• The geologic time scale- a scale that divides
  Earths 4.6 billion year history into distinct
  intervals of time.

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C. Eons- largest division of time 1) Hadean
Eon 2) Archean Eon 3) Proterozoic Eon 4)
Phanerozoic Eon
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• Eras- the eons are divided into eras.

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• Phanerozoic Eon has 3 eras.
• Paleozoic- no land animals at the beginning,
  mostly water animals, toward the end- some land
  animals and amphibians and insects.
• Mesozoic- Age of the Reptiles- Dinosaurs, some
  small mammals and birds
• Cenozoic- recent life- Age of mammals, humans
  show up here.

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• Periods- Eras are divided into Periods.
• 1)Paleozoic has 7 Periods.
• 2) Mesozoic has 3 Periods.
• 3) Cenozoic has 2 Periods.

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F. Epochs- Cenozoic has the periods divided into
epochs because we have some much information
about this Era.