"stable"@en . . . . . "Taken at the base of sandstones and siltstones of the 'corona facies', overlying volcaniclastic rocks of the Harthwaite Formation [Borrowdale Volcanic Group]"@en . "About 400m"@en . "DNSH"@en . "Dufton Shale Formation"@en . "Dufton Shale Formation"@en . "458.2"^^ . "Calcareous siltstone and siltstone with subsidiary calcareous mudstone and limestone and trace sandstone. Stratified bedrock. Occurs onshore. Deposited during the Caradoc Series - to - Ashgill Series (Ordovician Period) (458.2-443.1 Ma BP)."@en . "Dark grey, partly calcareous, siltstone and mudstone, with thin beds, lenticles or nodules of silty limestone. Poorly fossiliferous sandier beds occur near the top and base; at the base these include debris from the Borrowdale Volcanic Group with the commonly occuring brachiopod Trematis corona ['corona facies']"@en . "443.1"^^ . . "Overlain by limestones of the Swindale or Keisley limestone formations, or where these are absent, the Ashgill Formation"@en . .