"Oolitic Ironstone [Obsolete: use FRN]"@en . "449.75"^^ . "Fron Newydd Member"@en . "FRN"@en . . "Oolitic and Nodular Beds [Obsolete: use FRN]"@en . "Conformable transition from black nodular mudstones to paler mudstones of the Ty'r Gawen Mudstone Formation lacking in nodules. Contact not seen but makes a distinct feature or hollow."@en . "Ironstone and mudstone. Stratified bedrock. Occurs onshore. Deposited during the Caradoc Series (Ordovician Period) (458.2-449.75 Ma BP)."@en . . "Black pyritic mudstones with abundant phosphate nodules. Ooliths common in nodules - less common in matrix. Localised developments of pure oolitic ironstone."@en . . . "Fron Newydd Member"@en . . . "stable"@en . "458.2"^^ . . . . "Mostly about 25m in thickness but locally ranges up to 180m thick at western end of outcrop. Some rapid lateral variations in thickness."@en . . "Conformably overlies the Llyn y Gafr Volcanic Formation in the east of the outcrop where the boundary is sharp but poorly exposed. Unconformable contact to west, greatest at Llwyngwril, where it overlies the Allt Llwyd Formation."@en .