26 Notices of Memoirs — IT. J. L. Beadnell — Geology of Egypt. 



here when there existed only a slight depression in the Eocene and 

 Cretaceous rocks, ages in fact before erosion had carved out the 

 depression to its present form. The large amount of ferruginous 

 material and general character of the beds point to freshwater 

 lacustrine deposition and precipitation. Lithologically they are 

 often exactly similar to the Oligocene beds of the Fayum and Jebel 

 Ahmar, and to the deposits on the road between Feshn and the 

 oasis, and it may be that they are of the same age." 



The author states that the igneous rocks of Baharia are of Post- 

 Cretaceous, probably Oligocene, age, contemporaneous with the 

 basalt sheets of the Fayum, of Abu-Eoash and the desert to the 

 west, and of Abu-Zabel ; and that the andesites of the Libyan 

 desert at Bahnessa, Gara Soda, and Jebel Gebail were likewise 

 erupted at the same time. 



After describing the important folds which occur in Baharia the 

 author continues: — "The Cretaceous beds as a whole evidently 

 form a large anticline .... which has its axis more or less- 

 parallel to the syncline already described. It is continued into the 

 north end of Farafra, where the dip is well marked . . . - 

 Yet the Eocene beds forming the plateau are in general quite 

 horizontal, even in close proximity to inclined Cretaceous beds 

 . . . . it seems certain that the Cretaceous beds, after the 

 deposition of the White Chalk of Danian age, underwent upheaval, 

 denudation, and finally depression, before the deposition of the 

 earliest Tertiary beds. 



"In this part of Egypt it appears that the subsiding Cretaceous- 

 land had the form of a long, flat, irregular ridge of anticlinal 

 structure, extending from Dakhla oasis through Farafra, Baharia,. 

 and Abu-Roash. The northern end of this ridge was the last to 

 subside and receive Eocene deposits, which accounts for the fact 

 that in Farafra the Cretaceous is overlaid, always unconformably, 

 by the Esna Shales of the Lower Libyan, in Baharia by limestones 

 of the Upper Libyan, and at Abu-Eoash by still younger beds of 

 Lower and Upper Mokattam age." 



The author finds other evidence which " suggests the probability 

 that there was another period of possibly even more important 

 earth-movements in Post-Eocene times. In this case, it seems not 

 unlikely that the folding was closely connected with the important 

 series of earth-movements which took place in North-East Africa' 

 and South- West Asia in early Pliocene times, and which gave rise to 

 the formation of the chief topographical features of the countr}', such 

 as the Nile and Jordan valleys and their attendant series of lakes." 



The author's theory as to the origin of these wonderful depressions- 

 in the Libyan desert is interesting, and may be quoted in full. He 

 writes : — " Baharia is a self-contained depression without drainage- 

 outlet, so that the ordinary methods of removal of disintegrated 

 material do not here appl3^ Next, we have a large, flat, anticlinal 

 ridge of Cretaceous beds, with at least one subsidiar}^ sharp, parallel, 

 synclinal fold, overlaid by more or less horizontal beds of Eocene 

 limestone. Since the elevation of this part of North Africa into dry 



