PBDB Interval

International Chronostratigraphic Timescale

The interval definitions in this timescale are derived from the following sources:

K. M. Cohen, S.C. Finney, P.L. Gibbard and J.-X. Fan. 2023. The ICS International Chronostratigraphic Chart v2023/09. view
W. B. Harland, R. L. Armstrong, A. V. Cox, L. E. Craig, A. G. Smith and D. G. Smith. 1990. A Geologic Time Scale 1989. view
J. A. Lillegraven and M. C. McKenna. 1986. Fossil mammals from the "Mesaverde" Formation (Late Cretaceous, Judithian) of the Bighorn and Wind River basins, Wyoming, with definitions of Late Cretaceous North American Land-Mammal "Ages". American Museum Novitates 2840:1-68 view
F. M. Gradstein, J. G. Ogg, M. D. Schmitz and G. M. Ogg. 2020. Geologic Time Scale 2020 view
B. D. Webby. 1998. Steps toward a global standard for Ordovician stratigraphy. Newsletters in Stratigraphy 36:1-33 view
F. M. Gradstein, F. P. Agterberg, J. G. Ogg, J. Hardenbol, P. Van Veen, J. Thierry, and Z. Huang. 1995. A Triassic, Jurassic, and Cretaceous time scale. SEPM Special Publication 54 view
J. Palfy, P. L. Smith, and J. K. Mortensen. 2000. A U-Pb and 40Ar/39Ar time scale for the Jurassic. Canadian Journal of Earth Sciences 37(6):923-944 view

There are 59 timescales which overlap this one. show

Interval boundaries marked with * have been interpolated based on the differences between the ages for international timescale boundaries quoted in the source and the currently accepted ages for those boundaries.

Interval names marked with † are no longer in current use.

This timescale is used in the definition of 127245 collections

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International Chronostratigraphic Timescale			Ordovician of China			Ordovician of Britain
Ordovician	Late Ordovician	Hirnantian	Hirnantian	Xiaoxita †/Shikou	Wufeng †	Ashgill	Hirnantian			443.8
		Katian	Chientangkiangian				Rawtheyan			445.2
							Cautleyan			448.9 *
							Pusgillian			449.3 *
			Neichianshanian/Hanjiang				Pusgillian			449.5
						Caradoc	Streffordian	Onnian †		449.6 *
							Cheneyan			451.5 *
							Burrellian			452.7 *
		Sandbian								453
								Actonian †		453.2 *
								Marshbrookian †	Woolstonian †	454.2 *
								Longvillian †		455.2 *
							Aurelucian	Longvillian †		456.8 *
							Aurelucian	Soudleyan †/Harnagian/Costonian		457.4 *
	Middle Ordovician	Darriwilian	Darriwilian	Guniu †/Hulo		Llanvirn	Llandeilian/Llandeilo/Late Llandeilo/Middle Llandeilo/Early Llandeilo/Late Llanvirn			458.4
				Guniu †/Hulo			Abereiddian/Early Llanvirn			461.3 *
				Hunjiang †	Dawan †/Daobaowan/Ningkuo					466.3 *
		Dapingian	Dapingian							467.3
		Dapingian	Dapingian			Arenig	Fennian			468.4 *
	Early Ordovician	Floian	Yiyangian				Fennian			470
							Whitlandian			471.1 *
							Moridunian			474.3 *
		Tremadocian	Xinchangian			Tremadoc	Migneintian			477.7
					Lianghekou †		Migneintian			477.9 *
							Cressagian			480.8 *
										485 *
										485.4