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Geologic Time Scale: Eons, Eras and Periods


Geologic Time Scale: Eons, Eras and Periods

Fossil shark tooth

Andrew Alden photo

This geologic time scale shows all the defined units of period rank, along with the eras and eons that comprise them. Details beneath the table.


Eon Era Period Dates (m.y.)
Phanerozoic Cenozoic Quaternary 3-0
Neogene 23-3
Paleogene 66-23
Mesozoic Cretaceous 145-66
Jurassic 201-145
Triassic 252-201
Paleozoic Permian 299-252
Carboniferous 359-299
Devonian 419-359
Silurian 443-419
Ordovician 485-443
Cambrian 541-485
Proterozoic Neoproterozoic Ediacaran 635-541
Cryogenian 850-635
Tonian 1000-850
Mesoproterozoic Stenian 1200-1000
Ectasian 1400-1200
Calymmian 1600-1400
Paleoproterozoic Statherian 1800-1600
Orosirian 2050-1800
Rhyacian 2300-2050
Siderian 2500-2300
Archean Neoarchean   2800-2500
Mesoarchean   3200-2800
Paleoarchean   3600-3200
Eoarchean   4000-3600
Eon Era Period Dates (m.y.)
(c) 2013 Andrew Alden, licensed to About.com, Inc. (fair use policy). Data from Geologic Time Scale of 2013.

Back to the top-level geologic time scale

The periods of the Phanerozoic Eon are further subdivided into epochs; see those in the Phanerozoic Eon geologic time scale. Epochs are further subdivided into ages; see those in the Paleozoic Era, Mesozoic Era and Cenozoic Era geologic time scales.

The Proterozoic and Archean eons, along with the informal Hadean eon before 4000 million years ago, are together called Precambrian time.

The dates shown on this geologic time scale were specified by the International Commission on Stratigraphy in 2013. The colors were specified by the Committee for the Geologic Map of the World in 2009.

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