"stable"@en . "Grey Shale"@en . . "Sapropelite."@en . "346.7"^^ . . . "GYSH"@en . . . . "330.3"^^ . . "Grey Shale"@en . "Sapropelite. Stratified bedrock. Occurs onshore. Deposited during the Visean Age (Carboniferous Period) (346.7-330.3 Ma BP)."@en . .