Geologic Time

The geologic clock below depicts to scale the major units of geological time along with pivotal milestones of the history of Earth and life. The Hadean eon is now officially by the International Commission on Stratigraphy taken to begin at 4.0 Ga (billion years ago). Other geological period major events in the evolution of life on Earth; the Archean and Proterozoic are both eons, the Palaeozoic, Mesozoic and Cenozoic are eras of the Phanerozoic eon. The two million year Quaternary period, the time of recognizable humans, is too small to be visible at this scale.


Geologic Time as defined by the International Union of Geological Sciences: International Commission on Stratigraphy, 2002, 2003 and 2004 with color scheme that follows the official recommendation of the IUGS and ICS

Eon

Era

Period

ended:

beginning:

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Cenozoic

Neogene

0 Ma 23.03 Ma

Paleogene

23.03 Ma 65.5 ± 0.3 Ma

Mesozoic

Cretaceous

65.5 ± 0.3 Ma 145.5 ± 4.0 Ma

Jurassic

145.5 ± 4.0 Ma 199.6 ± 0.6 Ma

Triassic

199.6 ± 0.6 Ma 251.0 ± 0.4 Ma

Paleozoic

Permian

251.0 ± 0.4 Ma 299.0 ± 0.8 Ma

Carboniferous

299.0 ± 0.8 Ma 359.2 ± 2.5 Ma

Devonian

359.2 ± 2.5 Ma 416.0 ± 2.8 Ma

Silurian

416.0 ± 2.8 Ma 443.7 ± 1.5 Ma

Ordovician

443.7 ± 1.5 Ma 488.3 ± 1.7 Ma

Cambrian

488.3 ± 1.7 Ma 542.0 ± 1.0 Ma

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Neoproterozoic

Ediacaran
[Vendian]

542.0 ± 1.0 Ma 650 Ma

Cryogenian

650 Ma 850 Ma

Tonian

850 Ma 1000 Ma

Mesoproterozoic
[Riphean]

Stenian

1000 Ma 1200 Ma

Ectasian

1200 Ma 1400 Ma

Calymmian

1400 Ma 1600 Ma

Paleoproterozoic

Statherian

1600 Ma 1800 Ma

Orosirian

1800 Ma 2050 Ma

Rhyacian

2050 Ma 2300 Ma

Siderian

2300 Ma 2500 Ma

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Neoarchean

2500 Ma 2800 Ma

Mesoarchean

2800 Ma 3200 Ma

Paleoarchean

3200 Ma 3600 Ma

Eoarchean

3600 Ma not defined

More information on geologic time: