"Sandstone. Stratified bedrock. Occurs onshore. Deposited during the Hirnantian Age (Ordovician Period) (445.2-443.1 Ma BP)."@en . "443.1"^^ . . "stable"@en . "445.2"^^ . . . "COC"@en . . "Conwy Castle Grit Member"@en . "Conwy Castle Grit Member"@en . . . "Sandstone."@en . . .