Vol. 67.] DDKING THE CRETACEOUS AND EOCENE PERIODS. 143 



is practically an epitome of the most typical sequence of the 

 Eocene and Oligocene strata observed in North-Western Egypt, a 

 dip of 5° at this locality bringing up the whole of the Middle Eocene 

 strata within a limited area as follows : — 



Thickness in metres. 



1. Sandy limestone with chert cap ] 9 q f Probably 



2. Sandy limestones J " 1 Oligocene. 



3. Beds containing Ostrea fraasi, Carolia placu-\ 



noides, and Plicatula polymorpha, without I ^ f Upper 



nummulites [ I Moqattain. 



4. Brown Turritella Beds J 



5. Strata with small nummulites and Ostrea | , j^^ie 



fraasi : ............... \ - » Moqattam. 



6. Ostrea clot-beyi Beds J 



7. Gisortia Limestone 1 r Lower 



8. Yellow limestone (Gryphaa-pharaomcm Zone). V ... | ]y[ oqattam 



9. Nummulites-gizehensis Series J 



10. Gisopygus Beds Upper Libyan. 



The term Moqattam Beds, introduced by Zittel, has become 

 so well established in the literature that it does not seem advisable 

 to add a new name to the terminology : but a triple division of this 

 formation seems necessary, in order to bring out the very impoitant 

 change marked by the disappearance of the nummulites. This 

 triple division can be traced in all the important areas hitherto 

 studied (see Table, p. 141). 



IX. General Summary. 



The main points to which reference has been made in this paper 

 may be summarized as follows : — 



A. — 1. There was a gradual advance of the Cretaceous sea 

 over Egypt during Cenomanian to Danian times, from north or 

 north-east, five stages in this advance being indicated by the rela- 

 tions of the detrital Nubian Sandstone to the organic Cretaceous 

 limestones. These phases are : — 



(a) The Northern Egyptian type, extending from Sinai to 

 Baharia Oasis, in which the Nubian Sandstone underlies, 

 fossilif erous marls of Cenomanian age, while limestones 

 were forming during the remainder of the Upper Cretaceous Period 

 (Turonian, Senonian, and Danian). The Cenomanian beds contain 

 characteristic sea-urchins (Bemiaster of the cubicus type, etc.) and 

 oysters {Ostrea olisijjonensis, 0. saborbicuhtta, 0. Jlabellata, etc.). 

 A minor facies is the Bah aria n (Baharia Oasis), in which a 

 Cidaris-tJiomasi Bed is exceptionally developed at the close of the 

 Cenomanian. At Abu Ronsh, on the other hand, the Turonian 

 strata attain a thickness not elsewhere observed in Egypt. 



(6) The Wadi Qena type was recognized during my recent 

 expedition (1910) in the upper reaches of Wadis Qena, Tarfa, and 

 Hawashia. The characteristic feature is the alternation of 

 Nubian Sandstones with fossiliferous Cretaceous strata. 

 At least three typical sandstone-bands are present : (1) an Upper 



