388 Pro/! J. W. Dmoson — Notes on the Geology of Egypt. 



of the Pliocene and that of the later Pleistocene or Post-Glacial. 

 Between these periods there does not seem at present any certain 

 evidence to decide ; but perhaps the modern character of the fauna, 

 so far as it goes, may rather incline the balance to the latter period. 

 In this case we should have a fact pointing to the solution of the 

 difSculties felt by Lartet and Giinther respecting the identity of 

 Jordan and Nile fishes. We should at least be in presence of a 

 state of things in which the outlets of the Nile and the Jordan would 

 be much nearer together than at present. 



Since these "Isthmian" beds as we may name them for con- 

 venience, have been deposited, a submergence has occurred, in which 

 the modern sandstones and clays which flank them were deposited, 

 as those of the Eed Sea at least rise to heights nearly as great as 

 that of the Isthmian beds themselves. As seen near Suez, these 

 beds, some of which have been sufficiently consolidated by infiltra- 

 tion to form a serviceable building stone, consist of ordinary and 

 pebbly grey sandstones, holding modern shells, still retaining their 

 colours and animal matter, on which are in places marls and clays 

 holding gypsum and salt. Though some of these beds are as much 

 as forty feet above the sea, others are at the sea-level, and may be 

 still in procesG of deposition, more especially as certain low areas 

 of the desert are covered with salt water, and receive additional 

 deposits in high tides accompanied with storms, during which, I was 

 informed, large areas of desert south of Suez are overflowed by 

 the sea. Between Suez and Jebel Attaka we rode over extensive 

 tracts of low desert, which we were assured were occasionally over- 

 flowed in this way. These desert surfaces were in many places 

 strewn with recent shells, while workmen were quarrying, at and 

 near the sea-level, modern sandstone holding similar shells, and 

 which was being employed in building a pier at Suez. 



III. — Eocene and Cretaceous Geology. 



Eocene beds occur on both sides of the Nile, from Cairo to El Kab 

 near Edfou, and have been very well described by several geologists, 

 more especially by Fraas and Zittel. They are largely or domin- 

 antly calcareous, and rich in JVummulites in their middle portion. 

 According to Zittel they attain to the thickness of 760 metres, of 

 which nearly one-third, or 600 feet in vertical thickness, can be 

 seen in the single section of the Mokattam Hill, near Cairo.^ In 

 this section the Upper and Middle portions are there exposed. The 

 lower part is to be seen in the vicinity of Thebes. (Fig. 2.) 



Though these beds are nearly horizontal, or with only a slight 

 northerly dip, they seem to be traversed by lines of fault, running 

 approximately north and south and east and west, which sometimes 

 change the relative positions of the beds. On the Arabian or 

 Eastern side of the river, the beds have probably been supj)orted 

 by the subterranean extension of the old crystalline rocks of the 

 hills between the Nile and the Red Sea, and are consequently more 



1 See Prof. J. Milne, Geol. Mag. 1874, pp. 353-362 ; and review of Zittel's 

 recent work, Geol. Mag. 1884, pp. 172-179. 



