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
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
M. Kretzoi. 1942. Necroteuthis n. g. (Ceph. Dibr., Necroteuthidae N. F.) aus dem Oligozän von Budapest und das system der Dibranchiata. Földtani Közlöny 72:125-238 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 126699 collections

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International Chronostratigraphic Timescale			Ordovician of Britain				Ordovician of North America
Ordovician	Late Ordovician	Hirnantian	Ashgill	Hirnantian			Cincinnatian	Gamachian				443.8
		Katian		Rawtheyan				Gamachian				445.2
				Rawtheyan				Richmondian				446 *
				Cautleyan								448.9 *
				Pusgillian								449.3 *
			Caradoc	Streffordian	Onnian †							449.6 *
								Maysvillian	Rocklandian †/Shermanian/Ashbyan/Kirkfieldian/Blackriveran/Wildernessian/Trentonian/Franklinian			449.8 *
								Edenian				450.4 *
							Mohawkian	Chatfieldian				451.1 *
				Cheneyan								451.5 *
				Burrellian								452.7 *
		Sandbian										453
					Actonian †							453.2 *
					Actonian †			Turinian				453.7 *
					Marshbrookian †	Woolstonian †						454.2 *
					Longvillian †							455.2 *
				Aurelucian								456.8 *
							Whiterockian		Canadian †	Chazyan †/Marmor		457 *
					Soudleyan †/Harnagian/Costonian							457.4 *
	Middle Ordovician	Darriwilian	Llanvirn	Llandeilian/Llandeilo/Late Llandeilo/Middle Llandeilo/Early Llandeilo/Late Llanvirn								458.4
		Darriwilian		Abereiddian/Early Llanvirn								461.3 *
		Dapingian		Abereiddian/Early Llanvirn								467.3
			Arenig	Fennian								468.4 *
								Rangerian				469.1 *
	Early Ordovician	Floian					Ibexian	Blackhillsian		Jeffersonian †	Cassinian †	470
				Whitlandian				Blackhillsian				471.1 *
				Whitlandian				Tulean				473.9 *
				Moridunian								474.3 *
		Tremadocian	Tremadoc	Migneintian								477.7
				Migneintian				Stairsian				480.3 *
				Cressagian				Stairsian				480.8 *
				Cressagian				Skullrockian/Demingian				482 *
								Skullrockian/Demingian				485 *
												485.4
												487.5