"Harnagian Substage"@en . "Harnagian Substage is a substage in the British regional Ordovician stratigraphic scheme. It is the first of three substages of the Burrellian Stage. It is preceded by the Costonian Substage (Aurelucian Stage) and succeeded by the Soudleyan Substage (BGS Research Report RR/12/04, table 1)."@en . . "Harnagian Substage"@en . . "456.5"^^ . "OG"@en . "stable"@en . . "455.167"^^ . .