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Geologic Time Scale: Eons, Eras and Periods

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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.

EonEraPeriodDates (m.y.)
PhanerozoicCenozoicQuaternary3-0
Neogene23-3
Paleogene66-23
MesozoicCretaceous145-66
Jurassic201-145
Triassic252-201
PaleozoicPermian299-252
Carboniferous359-299
Devonian419-359
Silurian443-419
Ordovician485-443
Cambrian541-485
ProterozoicNeoproterozoicEdiacaran635-541
Cryogenian850-635
Tonian1000-850
MesoproterozoicStenian1200-1000
Ectasian1400-1200
Calymmian1600-1400
PaleoproterozoicStatherian1800-1600
Orosirian2050-1800
Rhyacian2300-2050
Siderian2500-2300
ArcheanNeoarchean
2800-2500
Mesoarchean
3200-2800
Paleoarchean
3600-3200
Eoarchean
4000-3600
EonEraPeriodDates (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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