122 DH. W. E. HUME ON SECULAK OSCILLATION IN EGYPT [Feb. I9II, 



2. A white limestone of similar lithological character, but without flints. 



In its lower portions are isolated bands of Ostrea vesicularis Goldf. 



and numerous scattered examples of Pecten farafrensis Zitt. (P. mayer- 



eymari Newt.). 

 The presence of a Terebratulina, though rare, is further evidence of the 

 D an i an age of this deposit, as the form resembles the species occurring in the 

 Danian of the Oases. Aggregates of cubical pyrite altered to limonite and stem- 

 like concretions of iron oxide are frequently present ; but, as a whole, the series 

 is throughout of great lithological similarity, and very poor in fossils. At the 

 extreme base of these strata is a band rich in Ostrea vesicularis var.judaica, 

 which attains a large size. 



3. Immediately beneath the Vesicularis Beds is a succession of grey- 



tinted strata, about 3 metres thick, characterized by an abundance of 

 sharks' teeth, vertebras, etc., especially Otodus auriculatus Ag. and 

 Corax pristodontus Ag. Specimens brought from this bed have 

 been analysed, and yielded over 20 per cent, of tricalcic phosphate. 

 Associated with them are large specimens of Plicatula, and imme- 

 diately below them comes a band containing an oyster which has 

 affinities with 0. nicaisei. 1 These probably correspond with the Cam- 

 panian farther south. 



4. Underlying these are the uppermost beds of the detrital series, consisting 



of well-banded green shales, alternating with beds of dark clay con- 

 taining rock-salt or brown phosphate-layers, the whole resting upon 

 flaggy sandstones. 



This Upper Nubian Sandstone and Shale is of geographical 

 importance, as it is more rapidly eroded than the Danian Lime- 

 stones on the west and the Santonian Beds on the east, resulting in 

 the production of an easily-traversed shallow depression at the 

 heads of Wadi Hemaiet and Wadi Abu Had. A notable feature in 

 this region is the steep local westward dip of the sandstones, angles 

 of from 23° to 35° having been noted. Farther east the strata are 

 horizontal, no ready explanation of these phenomena having been 

 obtained during the time available for study. 



These three divisions (2, 3, & 4) can be traced northwards to the 

 southern scarp of the Galala Hills ; but, in the low country where 

 the great drainage-systems of Wadis Qena, Tarfa, and Hawashia 

 have their origin, denudation of the softer members has initiated 

 the broad valley-depressions in which they take their rise. 



Owing to the rapid traverses necessitated by the waterless 

 character of the district west of Wadi Qena, it has not been 

 possible to make a detailed examination of the low country east of 

 the Upper Nubian Sandstone; but, in some conspicuous ridges 

 developed in eastward succession to this sandstone formation, a 

 further series has been recognized, consisting of: — 



5. Calcareous sandstone in slabs 2 inches thick, resting on 5 incnes of 



yellow sands. At the base these contain ferruginous concretions, 

 oysters of the acutirostris type, Plicatida, Tylostoma, and bivalve- 

 casts, the assemblage having a strong Santonian aspect. 



6. A new facies underlies these strata, a normal succession of flaggy 



yellow sandstones and ferruginous quartzites, typical of the Nubian 



\ I have to thank M. R. Fourtau for much valuable help in the identification 

 of the oysters, sea-urchins, and ammonites obtained in the Wadi Qena area 

 and other localities examined by me. 



