Geologic Time Scale: Periods

Eon	Era	Period	Dates (m.y.)
Phanerozoic	Cenozoic	Quaternary	3-0
		Neogene	23-3
		Paleogene	66-23
	Mesozoic	Cretaceous	146-66
		Jurassic	200-145
		Triassic	251-200
	Paleozoic	Permian	299-251
		Carboniferous	359-299
		Devonian	416-359
		Silurian	444-416
		Ordovician	488-444
		Cambrian	542-488
Proterozoic	Neoproterozoic	Ediacaran	635-542
		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) 2009 Andrew Alden, licensed to About.com, Inc. (fair use policy). Data from Geologic Time Scale of 2009.

Back to the top-level geologic time scale

This geologic time scale shows all the defined units of period rank, along with the eras and eons that comprise them. 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 2009. The colors were specified by the Committee for the Geologic Map of the World in 2009.

Subscribe to the Newsletter
Name	Email