140 



DK. W. F. HUME ON SECTJLAE OSCILLATION IN EGYPT [Feb. I9H,. 



1. Bed entirely composed of oysters (O.fraasi M.-E., 0. reili ] 



Fraas) 1 4 metres. 



2. Carolia-placunoides layer with Turritella casts J 



3. Very fossiliferous shelly layer, with Ostrea reili, trochoid \ 



shells, Turritellce, scattered Carolia L 4 metres. 



4. Beds of shell-fragments, mainly small oysters, with Balanus. J 



5. Beds of huge oystei-s about 1 metre. 



6. Bed of Ostrea reili. 



7. Yellow sands 8 metres. 



8. Yellow sands with white concretions and vertebras of 



Zeuglodon. 



In the plain at the base Nummulites gizehensis was present. 



If the Nummulites-gizeliensis Beds be synchronous throughout 

 Egypt, then these detrital deposits are the equivalents of the 

 highly fossiliferous limestones of the Moqattam Series and the 

 unfossiliferous limestones of the Sakkara Series, showing the 

 enormous local variations occurring during the greater part of 

 the Lower Moqattam epoch. 



The Upper Moqattam Series. 



Attention has already been directed to the marked lithological 

 variation in the beds forming the basal and summit layers of the 

 Moqattam Hill above Cairo, which led to the separation of the 

 Middle Eocene into two divisions. It is probable that any attempt 

 to separate the Upper from the Lower Moqattam Beds throughout 

 Egypt will not be successful, as the unconformity between them 

 is not, in any case, of an extensive character. Nevertheless, there 

 are certain features in which the typical Upper Moqattam Beds- 

 differ in a marked degree from the Lower Moqattam division. 



One of the most significant of these is the distribution of the 

 nummulites, a point which arrests attention when a number of 

 isolated sections are examined being that, while nummulites of 

 various species, especially Nummulites beaumonti, and the small 

 N. schweinfurthi. are extremely common up to a certain level, they 

 cease very abruptly ; the beds above them, often brownish-yellow, 

 though containing many fossils present in the nummulitiferous- 

 strata, show no traces of the presence of these foraminifera. In 

 general there need be no hesitation in referring these non-numm- 

 ulitic beds to the Upper Moqattam Series. Unfortunately, it is- 

 difficult to draw the base-line of this division, because certain 

 species which have been commonly regarded as typical Upper 

 Moqattam forms also occur in the nummulitiferous beds. Among 

 these we may especially note Ecliinolampas crameri de Lor., Anisaster 

 gibberulus Mich., and Ostrea clot-beyi Bell. 



This feature (namely, the absence of nummulites in the Upper 

 Moqattam), noted in the Moqattam area, in the Fayum, and near 

 the Pyramids, is widespread in its distribution. In the desert to 

 the south of the gravel-covered plain, or ' Serir,' lying between 

 Moela and Baharia Oases, and especially in the broken region known 

 as El Bahr, reappear thick strata, characterized by the abundance 

 of their fossil contents, their brown-red coloration, the rapidity 



