"stable"@en . "Onnian Substage"@en . . "Onnian Substage is a substage in the British regional Ordovician stratigraphic scheme. It is the second of two substages of the Streffordian Stage. It is preceded by the Actonian Substage and succeeded by the Pusgillian Stage (BGS Research Report RR/12/04, table 1)."@en . . . "449.75"^^ . "450.5"^^ . "Onnian Substage"@en . "ON"@en . .