142 DK. W. F. HUME ON SECULAE OSCILLATION IN EGYPT [Feb. I9II, 



I have purposely refrained from comparing these strata more 

 closely with the Eocene formations of Europe, as this would require 

 a more careful palaeontological analysis than time has permitted me 

 to undertake. Only such a study will finally decide whether the 

 Upper Moqattam as above defined should be regarded as Upper 

 Eocene, instead of being considered, as it was originally, the 

 uppermost member of the Middle Eocene. 



The Calcareous Grits. 



The final stages in the history of this passage from the widespread 

 Eocene sea to the Oligocene continental conditions are witnessed by 

 the calcareous grits, which underlie the pebble-gravels forming the 

 surface of much of the Western Desert of Egypt between the Fayum 

 and Baharia Oasis. In these the individual rounded sand-grains 

 are cemented in a calcareous paste. A typical section of this 

 Calcareous Grit series was studied in the Gebel Hadahid scarp, 

 where it is crossed by the main road from the Fayum to Baharia. 

 The succession is as follows, the beds dipping 5° northwards : — 



Thickness in metres. 



1. Quartz-chert pebble-gravels (forming the summit) ... 5 - 



2. Sa.idy limestone (composed of fossil fragments) 25 



o. Friable consolidated sands 15'5 



4. Very false-bedded sands (calcareous) 30 



5. Yellow clayey sands 1*6 



6. Sandy shales (very friable) with solid yellow sandy 



concretions 0'8 



7. Yellow clayey sands 40 



Total 32-4 



Below these in the valley is a Lucina-Q&st bed, overlying a sandy 

 layer with scattered Turritella and Cardita. This unfossiliferous 

 series is not of purelv local occurrence, for it reappears from under 

 the pebble-gravels to the north of Baharia, forming conspicuous 

 cliffs and the very marked hill to which the name of Had el Bahr 

 was given, which is composed of complex sandy grits. The same 

 beds were again observed at only 3 kilometres from the north- 

 western edge of the Baharia scarp. 



Though not actually traced step by step into the series so clearly 

 described by Mr. Beadnell in the ' Topography & Geology of the 

 Fayum Province' (Mem. Egypt. Geol. Surv. 1905), these strata must 

 represent his Fluvio-Marine division, and (judging from p. 63 

 of that memoir) probably that portion which has been classed with 

 the Upper Eocene. A similar calcareous grit frequently rises 

 through the gravel-beds, and may be regarded as Oligocene ; these 

 strata, therefore, appear to be of considerable importance, not 

 only as regards their palaeontological interest in connexion with 

 the occurrence of Arsinoitherium, etc., but also on account of their 

 wide distribution in the Libyan Desert. 



The succession in the El Bahr region north of Baharia Oasis 



