Hirnantian ICS Stage
(Gamachian)
From 445.6 +/- 1.5 To 443.7 +/- 1.5 Ma
Start Defined By: Potentially at base of the Normalograptus
extraordinarius-N. ojsuensis graptolite biozone.
End Defined By: Graptolites, lowest occurrences of Parakidograptus
acuminatus and Akidograptus ascensus.
Start Based On: Gradstein, Ogg, Smith, _A Geologic Time Scale 2004_
End Based On: Gradstein, Ogg, Smith, _A Geologic Time Scale 2004_
-- A Substage of --
Eon: Phanerozoic (542 - -5.5012e-005)
Era: Paleozoic (542 - 251)
Period: Ordovician (488.3 - 443.7)
Epoch: Late Ordovician (460.9 - 443.7)
Australian Stage: Bolindian (450 - 443.7)
General Stage: Ashgill (449 - 443.7)
North American Stage: Cincinnatian (451 - 443.7)
-- Preceeded By --
ICS Stage: Ordovician VI (455.8 - 445.6)
European Stage: Rawtheyan (446.5 - 445.6)
Regional Stage: Richmondian (449 - 445.6)
-- Followed By --
Period: Silurian (443.7 - 416)
Epoch: Early Silurian (443.7 - 422.9)
Sub-Epoch: Llandovery (443.7 - 428.2)
ICS Stage: Rhuddanian (443.7 - 439)
Australian Stage: Keiloran (443.7 - 433)
Chinese Stage: Longmaxian (443.7 - 438)
North American Stage: Medinan (443.7 - 438)
Regional Stage: Alexandrian (443.7 - 436)
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