"Limestone."@en . . "Dalton Limestone (Northumberland)"@en . . . "Dalton Limestone (Northumberland)"@en . "stable"@en . "Limestone. Stratified bedrock. Occurs onshore. Deposited during the Arnsbergian Substage (Carboniferous Period) (327-323.75 Ma BP)."@en . . "323.75"^^ . . "327.0"^^ . "DTNL"@en . . . .