"stable"@en . "HBHG"@en . . "Greenstone Conglomerate"@en . . "Bedrock. Occurs onshore. Formed during the Arenig Series - to - Abereiddian Stage (Ordovician Period) (477.1-461.25 Ma BP)."@en . "Greenstone Conglomerate"@en . "477.1"^^ . . . "461.25"^^ .