IN THE ESNA-IDFU REGION, NILE VALLEY, EGYPT 33 



into three distinct rock units which he described from the base upwards as follows : 



1. Beds of Exogyra overwegi von Buch, (Overwegischichten). 



2. Greenish and ashen-grey paper-like shales. 



3. Snow-white, well-bedded limestones or earthy chalk with Ananchytes ovata. 



The fossils collected by Zittel from these three rock units were described by Quass 

 (1902) and Wanner (1902) who confirmed Zittel's classification, assigning all these 

 rock units to the Danian. Moreover, Quass considered Zittel's shale and chalk units 

 as two different fades of the same stratigraphical horizon, which he regarded as the 

 Upper Danian. 



Apparently Zittel used the term Danain in a much broader sense than that of the 

 original definition of the term. While no known ammonifies or inocerami are 

 recorded to range up into the type Danian, Zittel recorded the genera Libycoceras, 

 Baculites and Inoceramus in his " overwegischichten ", but still included it in the 

 Danian. Probably he was confused by Mayer-Eymar (1872) who had extended the 

 Danian to include the Campanian, the Maestrichtian, and the Danian proper and 

 thus added to the confusion regarding the limits between these stages and sub-stages. 

 However, analysis of Zittel's Danian in the light of the present investigation shows 

 that it includes the Upper Campanian, the Maestrichtian and most of the Paloecene. 

 It also indicates a marked break between the Maestrichtian and the overlying 

 Paleocene strata in spite of Zittel's emphasis on the absolute conformity of the succes- 

 sion. Nevertheless, Zittel's concept and classification of the Danian in Egypt were 

 generally followed by later authors, e.g. Ball (1900), Beadnell (1901, I905),0ppenheim 

 (1902) and Hume (1911), where the latter included as Danian all the succession of 

 strata between the top of the Campanian and the base of the Lower Eocene. 



Blanckenhorn (1900) considered Zittel's " overwegischichten " to belong to the 

 Maestrichtian, which he equated with the Dordonian, Upper Aturian and Lower 

 Danian. Later in 1921, he reconsidered the " overwegschichten " to belong to the 

 Campanian and related the other two divisions to the Danian (which he regarded as 

 the youngest stage of the Senonian), ignoring completely the Maestrichtian. 

 Apparently he followed de Grossouvre (1897, 1901) who had included the Maestrich- 

 tian within the Campanian as its uppermost part. However, Fourtau (1904), 

 following Arnaud (1897), considered the Upper Senonian to include the Campanian 

 as its lower horizon and the Maestrichtian as its upper, while he regarded the Danian 

 as a distinct stage, younger than and equal in rank to the Senonian stage. He also 

 considered some fossils of Zittel's " overwegischichten " to belong to the Campanian 

 and reasonably stated that the limit between the Maestrichtian and the Danian in 

 Egypt should be drawn at the top of the highest bed with ammonites. 



Beadnell (1905) classified the Upper Cretaceous-Lower Tertiary rocks of the Nile 

 Valley, south of Esna, into Campanian, Danian, Passage beds and Lower Libyan, 

 advocating the absolute conformity of the succesion which was previously emphasized 

 by Zittel (1883). Following the general belief of his time, he ignored the Maestricht- 



