1999  Korn, p.149: Madène El Mrakib, 30 km SE of Fezzou, 80
           km SSW of Erfoud, southern Ma'der. Mainly fine
           clastics, usually greenish claystones, with thin
           intercalations of marly or calcareous nodular layers
           (text-fig.2). Monotonous succession of claystones with
           interbedded thin carbonates and black shales.