"stable"@en . "Passes conformably upwards into Caradoc shales."@en . "468.0"^^ . . . . "Castell Limestone Formation"@en . "Limestone with subsidiary mudstone. Stratified bedrock. Occurs onshore. Deposited during the Abereiddian Stage - to - Caradoc Series (Ordovician Period) (468-449.75 Ma BP)."@en . "Conformably overlies the Caerhys Shale Formation with gradational boundary."@en . "449.75"^^ . "Bluish grey limestones with interbedded mudstones."@en . "Castell Limestone Formation"@en . "25m"@en . . "CLI"@en . .