"Mudstone with subsidiary sandstone. Stratified bedrock. Occurs onshore. Deposited during the Telychian Age (Silurian Period) (438.6-432.9 Ma BP)."@en . "Yellowish-brown, thinly bedded shales and sandstones containing three graptolite-bearing horizons."@en . "432.9"^^ . "Blair Shales [Obsolete: use BLRS]"@en . . . . "Conformably overlain by the Knockgardner Sandstone."@en . . "Blair Shale Formation"@en . . . "Blair Flags and Shales [Obsolete: use BLRS]"@en . . . "Conformable on the Drumyork Flags Formation."@en . "BLRS"@en . "Blair Shale Formation"@en . "stable"@en . "438.6"^^ . "84 m thick."@en . . .