"Sandstone. Stratified bedrock. Occurs onshore. Deposited during the Chokierian Substage (Carboniferous Period) (323.75-323 Ma BP)."@en . . . . "Brocka Bank Grit"@en . "BBK"@en . . "Brocka Bank Grit"@en . "stable"@en . "323.75"^^ . . "Thickly bedded, coarse-grained sandstone."@en . . "To c.25m"@en . . "323.0"^^ . .