"Base succeeds ribbon banded mudstones of the Nantglyn Flags Formation."@en . "Elwy Group [Obsolete: use EY]"@en . . "422.7"^^ . . "Elwy Formation"@en . "Unconformably overlain by Carboniferous Limestone."@en . . ">1750 metres."@en . "stable"@en . "Disturbed beds, striped silty mudstones and subordinate sandstones with lateral facies changes."@en . . . . "Silty mudstone with subsidiary sandstone. Stratified bedrock. Occurs onshore. Deposited during the Ludlow Epoch (Silurian Period) (426.7-422.7 Ma BP)."@en . "Elwy Formation"@en . "EY"@en . . "426.7"^^ . .