Geologic Time Scale

Hadean, Archean and Proterozoic Eons

Click here for the Phanerozoic Eon

  EON HADEAN  
  ERA none
PERIOD none
EPOCH none
YEARS 4.6 - 4 bya

  EON ARCHEAN  ARCHEAN ARCHEAN ARCHEAN
  ERA Eoarchean Paleoarchean Mesoarchean Neoarchean
PERIOD none none none none
EPOCH none none none none
YEARS 4 - 3.6 bya 3.6 - 3.2 bya 3.2 - 2.8 bya 2.8 - 2.5 bya

  EON PROTEROZOIC PROTEROZOIC PROTEROZOIC PROTEROZOIC PROTEROZOIC PROTEROZOIC PROTEROZOIC PROTEROZOIC PROTEROZOIC PROTEROZOIC
  ERA Paleoproterozoic Paleoproterozoic Paleoproterozoic Paleoproterozoic Mesoproterozoic Mesoproterozoic Mesoproterozoic Neoproterozoic Neoproterozoic Neoproterozoic
PERIOD  Siderian Rhyacian Orosirian Statherian Calymmian Ectasian Stenian Tonian Cryogenian Ediacaran
EPOCH none none none none none none none none none none
YEARS 2.5 - 2.3 bya 2.3 - 2.05 bya 2.05 - 1.8 bya 1.8 - 1.6 bya 1.6 - 1.4 bya 1.4 - 1.2 bya 1.2 - 1.0 bya 1.0 - .850 bya .850 - .635 bya .635 - .542 bya


"bya" means billions of years ago

The Earth's geological ages are classified as follows:

4 eons, each of which lasts approximately a billion years.
10 eras, each lasting about several hundred million years.
22 periods, which last about a hundred million years each. Only the proterozoic and the phanerozoic eons are divided into periods.
34 epochs, each lasting tens of millions of years. Only the phanerozoic eon is divided into epochs.


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