Athro Limited, Education on the Web
 The geologic time scale 

How long is Geologic Time? Millions of years are hard to imagine. Try our Geological time scale metaphor calculator.

How well do you know the Geologic time scale? Try our time scale quiz

Major divisions of the geologic time scale

Time in millions of years before the present.
Eon Era Period Events
Phanerozoic
(544ma-today)
Cenozoic
(64.5ma-today)
Neogene
(23ma-today)
    Recent
    Pleistocene
    Pliocene
    Miocene
Modern Mass Extinction



Paleogene
(64.5ma-23ma)
    Oligocene
    Eocene
    Paleocene
Mesozoic
(245ma-64.5ma)
Cretaceous
(146ma-64.5ma)
End Cretaceous Mass Extinction
Jurassic
(208ma-146ma)
Triassic
(245ma-208ma)
Paleozoic
(544ma-245ma)
Permian
(286ma-245ma)
End Permian Mass Extinction
Carboniferous
(360ma-286ma)
  Pennsylvanian(US)
  Mississippian(US)
Devonian
(410ma-360ma)
Silurian
(440ma-410ma)
Ordovician
(505ma-440ma)
First Snails
Cambrian
(544ma-505ma)
Proterozoic
(2500ma-544ma)
Neoproterozoic
(900ma-544ma)
Ediacaran fauna
Vendian Glaciation
Crown eukariote radiation
Mesoproterozoic
(1600ma-900ma)
Paleoproterozoic
(2500ma-900ma)
Oxygen in atmosphere
Formation of Continental Plates
Archean
(3800ma-2500ma)
Origin of life
Hadean
(4600ma-3800ma)
No surviving rocks on earth
Ocean vaporizing meteor impacts
Accretion of Earth

Sources: Assembled from various sources. The overall framework is from:Harland et al., 1990; Palmer, 1983. A number of dates and events are from a variety of more recent (1990s) sources.
Part of the Athro, Limited web site.
Copyright © 1998, 1999, 2000 Athro, Limited. All Rights Reserved.
Written by Paul J. Morris mole@morris.net and Susan F. Morris
Maintained by Athro Limited
Date Created: 2 Jan 1998
Last Updated: 2000 August 11