Trof. J. W. Dawson — Notes on the Qeologij of Egypt. 391 



M. Le Vaillant^ has given a detailed section of the beds of Jebel 

 Attaka, of which the following is a summary in descending order : 



-p ^ (■ Dolomitic Limestone — Poianiides and Cerithium (Holds 



■ ■ ■ ■ ( also NummuUtes and various Eocene bivalves) 150 metres. 



f White Chalk 50 ,, 



j Ked Marly and Gypseous Band 7 , , 



p J Alternations of Chalk and Dolomite 109 ,, 



ORETACEOLs S White Chalk 2 „ 



I Dolomite — 2 species of Hippurites, Ostrea larva, Janira 



(_ sexanffularis, Jixo(/yra 53 , , 



Total 371 ,, 



If we compare this with the Egyptian section of Zittel, as given 

 in this Magazine (April, 1884), bearing in mind the fact that the 

 Jebel Attaka section does not reach to the base of the Cretaceous, 

 we shall be able to ajopreciate the different development of the 

 formations, even within the space of sixty miles. 



It would further appear that throughout the Eastern Mediterra- 

 nean, there is no stratigraphical break between the Cretaceous and 

 Eocene, while two periods of partial elevation and shallow-water 

 conditions are represented by the Lignitiferous Zone of the Cretaceous, 

 which occurs in the Lebanon as well as in Eg3'pt, and by the argil- 

 laceous and gypseous beds near the top of the Eocene in Egypt. 

 The periods of greatest limestone deposition would seem to have been 

 in the Middle and Upper Cretaceous in Syria, and in the Middle 

 Eocene in Egypt. These facts serve to illustrate the importance of a 

 detailed study of rocks and fossils in each locality, before instituting 

 comparisons of horizons. The difficulties hitherto experienced in this 

 have also arisen, in part at least, from a too close adherence to 

 European distinctions, which may not be strictly applicable in the 

 East, though the general order of succession of fossils is no doubt 

 similar in both. 



The question of the age of the Nubian sandstones is at present 

 somewhat difficult, and has recently been ably discussed hy Hudleston.- 

 On the Nile it succeeds at Silsilis the Cretaceous beds above referred 

 to, in descending order, and apparently conformably, and forms an 

 east and west ridge through which the river passes in a narrow 

 gorge. In this outcrop are the celebrated quarries from which so 

 much of the stone of the Egyptian temples was derived. The Silsilis 

 exposure is, however, limited in breadth, and south of it beds 

 similar to those on the north recur, leading to the supposition 

 that there is here an east and west fault or roll of the strata, 

 repeating the beds, or else that there are two distinct sandstones. 

 I had not opportunity to work out this point satisfactorily, but 

 believe that there is little reason to doubt the existence of a down- 

 throw fault, repeating the Cretaceous beds, at the south of the 



1 Bulletin Geol. Soc. of France. 



^ As Hudleston has remarked, Bauerman's section of the Zib escarpment 

 exhibits a lower sandstone in connection with which the fossils regarded as Carbon- 

 iferous occur ; while higher in the series there are other sandstones associated with 

 calcareous beds holding undoubted Cretaceous fossils. Geology of Palestine, Pro- 

 ceedings Geol. Assoc, vol. viii. 



