PBDB Interval Range

450.2 - 443.1 Ma

International Chronostratigraphic Timescale			Ordovician of North America					Ordovician of Britain
Ordovician	Late Ordovician	Hirnantian	Cincinnatian	Gamachian				Ashgill	Hirnantian			443.1
		Katian		Gamachian					Rawtheyan			445.2
				Richmondian					Rawtheyan			445.5
									Cautleyan			448.8
									Pusgillian			449.2
								Caradoc	Streffordian	Onnian †		449.5
				Maysvillian	Rocklandian †/Shermanian/Ashbyan/Kirkfieldian/Blackriveran/Wildernessian/Trentonian/Franklinian							449.6
				Edenian								450.2
			Mohawkian	Chatfieldian								451
									Cheneyan			451.3
									Burrellian			452.5
		Sandbian										452.8
										Actonian †		453
				Turinian						Actonian †		453.8
										Marshbrookian †	Woolstonian †	454
										Longvillian †		455
									Aurelucian	Longvillian †		456.6
										Soudleyan †/Harnagian/Costonian		457.2
			Whiterockian		Canadian †	Chazyan †/Marmor				Soudleyan †/Harnagian/Costonian		457.3
	Middle Ordovician	Darriwilian						Llanvirn	Llandeilian/Llandeilo/Late Llandeilo/Middle Llandeilo/Early Llandeilo/Late Llanvirn			458.2
								Llanvirn	Abereiddian/Early Llanvirn			461.1
								Arenig	Fennian			468
		Dapingian										469.4
				Rangerian								470.3
				Rangerian					Whitlandian			470.7
	Early Ordovician	Floian	Ibexian	Blackhillsian		Jeffersonian †	Cassinian †		Whitlandian			471.3
				Blackhillsian					Moridunian			473.8
				Tulean					Moridunian			475.3 *
		Tremadocian						Tremadoc	Migneintian			477.1
									Cressagian			481.1 *
				Stairsian								481.7 *
				Skullrockian/Demingian								483.4 *
				Skullrockian/Demingian								486.4 *
												486.85 *
												488.9