Geologic Time Scale

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Geologic Time Scale

• Chapter 2, Section 3 Unit A
• Science 8
• Messana

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Review

• What did you decide was more usefultree rings or
  ice cores?
• Why?

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Geological Time - really, really, really long!

• Motion pictures are generally projected at 32
  frames per second. Therefore, each frame (image)
  is on the screen for only split second- let each
  frame represent 100 years.
• Start movie at present and go back in time.
• The Declaration of Independence would show up
  1/16 of a second into the movie.
• The Christian era (BC-AD boundary) would be 3/4
  of a second into the movie.
• The most recent Ice Age would be 7 seconds into
  it.
• The movie would run about 6 hours before we got
  to the end of the Mesozoic era (extinction of the
  dinosaurs).
• We'd have to watch the movie for about 2 days to
  see the beginning of the Paleozoic era
  (macroscopic life).
• The whole movie (to the beginning of geologic
  time on Earth) would be approximately 16 days
  long!

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• https//www.youtube.com/watch?v9ESo9oSqXns

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A football field representing Geologic Time
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Geologic Time Scale

• Geologic Time Scale a timeline of Earths
  History divided into periods of time by major
  events or changes on Earth
• What do we call these major events or changes?

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• Eon the longest division of geological time.
• Era a major division of geological time an era
  is usually divided into two or more periods.
  (most recent eon 3 eras)
• Period Each era is subdivided into a of
  periods
• Epoch smallest division of time a subdivision
  of a period

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Catastrophic Events

• Catastrophic Events events that cause major
  destruction or change life completely
• Examples
• Mass extinctions
• Ice Ages
• Meteors
• Pangaea
• Major volcanic eruptions

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EONS largest division of time

• 1. Hadean
• 2. Archean
• 3. Proterozoic
• 4. Phanerozoic
• Eons 1-3 make up Precambrian Time (90 of
  Earths History)
• Largest to Smallest amounts of TIME.
• Eons -gt Eras -gt Periods -gt Epochs
• Change in name is due major geologic or climatic
  events!

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PRECAMBRIAN TIME

• Most of Earths history
• OR
• 90 of Earths history
• Lasted nearly 4 billion years of Earths 4.6
  billion years
• Volcanic ash dust -gtclouds formed -gtrain
• Single-celled micro-organisms in ocean at end
• No animals!
• No plants!
• Turn Paper Please!!

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Phanerozoic Eon

• 544 million years ago present
• Explosion of Life!
• 3 Eras
• Paleozoic Era Age of Amphibians
• Mesozoic Era Age of Dinosaurs
• Cenozoic Era Age of Mammals

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Eras of Time Paleozoic Era Ancient

• 544 mya 248 mya
• All life in ocean until end
• Fish developed
• Reptiles, Insects, Ferns developed moving life
  onto land at end
• Ends with a Mass Extinction (from a meteor
  strike?) kills 90 of all ocean species
• EVOLUTION is beginning to emerge!

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Mesozoic Era Middle

• 248 mya 65 mya
• PANGAEA- begins to break apart (about 200 million
  yrs ago!!!
• Dinosaurs rule!
• Small mammals, birds, flowering plants
• Ends with Mass Extinction due to meteor strike
  off Mexico -gtdust cloud blocked sunlight, killed
  plant life and affected food chain

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Cenozoic Era Recent

• 65 mya Present
• Large warm-blooded mammals, modern birds,
  flowering plants
• Animals developed migration techniques
• Tertiary Period
• Quaternary PERIOD Past 2 million yrs
• Ice ages
• 1st modern human fossils 100,000 yrs old
• Humans are 7 seconds of 12 hour clock!! 0

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ReminderTheory of Uniformitarianism

• Earth is constantly changing due to the same
  basic forces
• EX Slow erosion, plate movement
• Fast volcano, earthquake