128 DB. W. E. HUME ON SECULAR OSCILLATION" IN EGYPT [Feb. ipil, 



9. In many cases these lower members of the fossiliferous Cretaceous 

 series are underlain by further greenish-coloured shales, or may be 

 immediately succeeded by the uppermost layers of the Nubian 

 Sandstone. 



Before proceeding to consider the latter, the general conclusions 

 as to this interesting Cretaceous series may be summarized. 



Its age. — The following table shows better than words the 

 relations of this fossiliferous series to the strata of similar age both 

 on the west and on the north. 



Oases. Esna District. ■ East op Qena. 



Lower Libyan Limestone. Lower Libyan Lime- Lower Libyan Limestone. 



stone. 



Upper Shales. Upper Esna Shales. White marly beds. 1 



Upper Esna Beds. J 



White Chalk. White Chalk. Marly limestone. 



Ashen-grey Paper-shales. Lower Esna Shales. Greenish shales. 



Lower Esna Beds. 



Pecten Marls and White marly limestone 



Shales. with Pecten. 1 



Exogyra-overwegi Beds. Cephalopod Bed. "1 Ptychoceras Bed. J 



Oyster Limestone. J Coprolite Bed. 



Coprolite Bed. Oyster Limestone. 



An examination of the foregoing table shows a broad general 

 resemblance between the series in the three localities, and there 

 cannot be the slightest hesitation in agreeing with Mr. Beadnell, 

 in regarding the beds from the summit of the White Chalk to the 

 base of the Pecten Marls as of Danian age. Indeed, I should be 

 inclined to admit the Upper Esna Shales into the same category,, 

 such forms as have been found in these strata resembling those 

 of the underlying shales, and having no connexion with the beds 

 containing the varied Eocene fauna, rich in echinoderms and 

 Operculinse, which immediately overlie them. 



On the other hand, all writers on this subject seem to be agreed 

 that the Cephalopod and Oyster Beds are of Campanian age, and 

 so the controversy with regard to the Cretaceous age of the whole 

 series appears to be settled. 



The important changes noted, passing from north to south, are 

 therefore : 



(1) In the regions north of latitude 26° K, the Danian White Chalk is 

 mainly unfossiliferous, except for scattered Pectens and oysters. The 

 rich coralline and bivalve fauna of the Oases has never been observed, 

 and shales are absent in the series. 



(2) In contrast, the Danian Series of the Oases is composed of both 

 shales and white limestones: these contain small corals, univalves, and 

 bivalves, and consequently they probably indicate shallower- water con- 

 ditions than are exhibited farther to the north-east, where such life as 

 existed was micro-organic. 



(3) In the neighbourhood of Esna the Western and Eastern Danian 

 types are co- existent and closely related. 



The third Cretaceous facies occupying the greater part of Southern 

 Egypt is thus divisible into an Eastern and a Western division, 



