4 oo SCIENCE PROGRESS. 



Carboniferous band, and clearly this must be post-Carbon- 

 iferous and pre-Cretaceous, or possibly early Cretaceous. 

 But we can say little beyond this. If the apparent absence 

 of unconformity is to be taken as evidence, the whole of the 

 period between the Carboniferous and the Upper Cretaceous 

 must be represented ; and this is scarcely probable. 



There is nothing to show which part of the Wadi Araba 

 sequence corresponds with the Nubian Sandstone of the 

 Libyan Desert, excepting only the occurrence of Araucari- 

 oxylon — a genus of great vertical range. Lyons remarks 

 that he is unable to distinguish any divisions in the sand- 

 stone of the Libyan Desert, and refers the whole of it to 

 the Cenomanian. But in so extensive and so imperfectly 

 examined an area, negative evidence can go for little. 



Cretaceous- -The Cretaceous rocks form the floor of the 

 fertile belt in Upper Egypt, which includes the Farafra, 

 Dakhla, Kharga, and Kurkur oases. In the case of the 

 Dakhla oasis it also forms the northern wall. The Baharia 

 oasis, which lies in a depression in the Eocene plateau, is 

 also cut down to the Cretaceous rocks below. South of the 

 Kharga oasis there are one or two outliers resting upon the 

 Nubian Sandstone. Bir Murr, for example, is stated by 

 Lyons (16) to lie in Cretaceous rocks; and the Selima 

 oasis, S.W. of Wadi Haifa, is also believed by him to be 

 Cretaceous. 



About a dozen miles west of the great pyramids there is 

 a rhomboidal area of Cretaceous rocks, which has been 

 brought into its present position among the Tertiary de- 

 posits by faults along its four sides. This area has been 

 described by Mayer-Eymar (i/), Schweinfurth (28), and 

 Walther. 



On the east side of the Nile the Cretaceous forms a 

 belt which lies along the western flank of the mountain 

 chain near the shores of the Red Sea. It has also been 

 found in patches on the eastern flank. It occurs, too, in 

 the Wadi Arabi, and further north still it forms the northern 

 foot of Jebel Attaka, the mountain which is so conspicuous 

 an object from the port of Suez. 



The Cretaceous of the Upper Egyptian oases has 



