Notices of Memoirs — H. J. L. Beadncll — Gcologi/ of Egypt. 25 



The author then discusses separately several t^'pical localities, 

 Avhich may be briefly alluded to. 



Abu-Eoash. — This peculiarly interesting Cretaceous complex, near 

 ■Cairo, lias been described by Walther and Schweinfurtli as having 

 been brought into position among the Eocene deposits by faults 

 along its four sides. This view, however, is strongly opposed by 

 the author, who maintains that the fault theory is absolutely 

 untenable, " as a most casual examination of the boundary of the 

 ■Cretaceous, at almost any point where its junction with the Eocene 

 was visible, instead of suggesting the existence of faults, yielded 

 ■indubitable evidence of their absence, and the presence instead of 

 a well-marked unconformity." At some points "the upper surface 

 of the white chalk of the Cretaceous shows a most irregularly 

 eroded surface, which is covered by a bed of rolled pebbles, some- 

 times a metre thick, the latter being overlaid by a thick bed of 

 Eocene shelly limestone, followed b}' a series full of characteristic 

 Upper Mokattam fossils," The author further points out the 

 existence in this area of Danian beds, the uppermost member 

 (White Chalk) being apparently homotaxial with the White Chalk 

 of Baharia and Farafra. 



Baharia Oasis. — Of the remarkable sand belt which occurs 

 between the Nile Valley and this oasis, the author says : — " This 

 sand belt has a total breadth of five kilometres, and runs slightly 

 west of north and east of south (parallel, in fact, to the normal 

 direction of the wind). Its origin is much further north, probably 

 in the neighbourhood of the oasis of ]\Ioghara, while to the south 

 it runs, as far as known unbroken, into the depression of Kharga, 

 whence, after a slight break, it continues southwards. Its length 

 ■is thus certainly over 350 kilometres. The dunes are composed of 

 light-yellow, siliceous, well-rounded sand-grains. The steepest sides 

 ■ are those facing west, which have an angle of 30^-31°. It is 

 a remarkable sight, this narrow band of sand dunes extending across 

 the open desert as far as the eye can reach, maintaining an almost 

 exactly straight course, an even breadth, and with sides as well 

 defined as if drawn with the edge of a ruler." 



The author's work shows that, contrary to original ideas, there is 

 •in reality a remarkable development of Cretaceous rocks in the 

 •oasis of Baharia and the surrounding desert on the west and south 

 •«ides. 



The lowest beds, consisting of sandstones, claj's, and marls, attain 

 a thickness of 170 metres, and are of Cenoraanian age. Above theni 

 come limestones and variegated sandstones (-15 metres), followed by 

 white chalk of Danian age, 40 metres thick. (See Table.) 



As at Abu-Roash, the junction between the Cretaceous and 

 Eocene is unconformable, the deposits of the latter overlapping 

 •successively the different beds of the former. 



The author, in discussing the age and origin of the peculiar 

 ferruginous quartzites which so constantly cap the numerous 

 isolated hills within the depression, brings forward evidence which 

 tends to show that these " were deposited in a lake which formed 



