. "Belper Grit"@en . . . "Belper Grit"@en . "Sandstone. Stratified bedrock. Occurs onshore. Deposited during the Marsdenian Substage (Carboniferous Period) (321.5-320 Ma BP)."@en . "stable"@en . . . "321.5"^^ . "Sandstone."@en . . "320.0"^^ . "BPG"@en . . .