The section is much obscured by downwash and talus of angular fragments of dolerite, sand, shale, etc. This downwash of shale and clay is often covered by a hard coating of salt and sand cemented together, sometimes having the appearance of regular beds. The following is a detailed section measured at the well-marked isolated conical hill near the western escarpment, 10 kilometres north-east of El Qasr (See Plate I.) The series is here capped by 6 metres of nodular and hard compact limestone with _Nummulites_, _Operculina_, _Lucina_, etc., of Lower Eocene (Libyan series) age. _Top._ (Hard compact limestone with _Nummulites_, etc., Metres. Eocene). Shaly clays with ferruginous bands, occasionally containing _Exogyra_ shells; alternations of shales and shaly sandstones. 7·4 Soft shaly and crumbly sandstones, with many hard ferruginous bands and shaly clays. In the sandstone occur solid vertical rods of ironstone 5 centimetres in diameter, with concentric structure 21·0 Gray marls with plant-stems and leaves 1·5 Yellow sandstone, well-marked thick compact bed, false-bedded 11·5 Hard ferruginous band with fish-remains 0·2 Gray shales 1·5 Soft beds of crumbly sand, harder sand-rock, with clayey layers and ferruginous bands 6·0 Shaly clays with dark-red ferruginous sandy layers, with gasteropod and _Exogyra_ shells. Green shaly sandstone on top, and gray sandy clays below 16·0 White and gray-bedded sand-rock 9·0 Obscured beds, one containing small _Exogyra_ and gasteropods. 15·0 Shaly sandstone with hard reddish nodular ferruginous bands containing gasteropods and _Exogyra_. 3·5 Sandy beds, hidden by downwash 6·0 Ferruginous bands containing _Exogyra_ casts } } 20·0 Sandy shaly clay, false-bedded, with white } sand-rock. Plant-remains } Bed of white sand-rock 1·0 Thinly laminated gray shale 2·0 Reddish-brown nodular ferruginous band 0·2 Sandy or clayey beds, obscured by downwash } } 9·0 Sandy clay } Sandy beds with dark-brown ferruginous bands 13·0