148 CRETACEOUS AND EOCENE OF EGYPT. [Feb. I9H, 



unconformity, even if any, between the freshwater Cretaceous and 

 the freshwater Tertiary. 



Dr. Falconer had spoken of an unconformity between Eocene and 

 Cretaceous rocks in Northern Nigeria. But would that necessarily 

 imply an unconformity between Eocene and Cretaceous in Erench 

 territory to the west of Northern Nigeria, or in Southern Nigeria ? 

 Might there not have been, in some parts of the great Cretaceo- 

 Eocene basin or group of smaller basins that formerly existed in 

 Northern Africa, a transition from marine Cretaceous to marine 

 Eocene, as in Southern Egypt, or from lacustro-estuarine Cretaceous 

 to a similar group in the Eocene ? Differential movement of the 

 land-surface could cause in local areas alternations between sedi- 

 mentation and erosion, with considerable or intense folding and 

 faulting in one area and little or none in another. 



The Author, in reply, said that the precipices in Egypt were due 

 in many cases to direct erosion by water, acting during very short 

 periods with exceptional violence. In other instances, where 

 great thicknesses of Eocene limestone rested upon soft shales, the 

 latter yielded under the pressure, causing masses of limestone to be 

 broken off, and thus leaving new precipice faces. 



Erosion by fresh and salt water was naturally very important, 

 the point being that the 'remade' biscuit-coloured limestones showed 

 the effects of such erosion in a much higher degree than was the 

 case with the true Danian limestones underlying them. 



The opinion as to the Cretaceous and Eocene age of the gypsum 

 at Jemsa should be still considered sub judice, no definite evidence 

 being available. Undoubtedly there were large deposits of gypsum 

 of very varied ages in Egypt, from the Pliocene downwards ; and 

 each of these had to be considered on its own merits. 



The Author further said that he had not visited Cyprus, and the 

 question of the origin of the crystalline limestones there, as well as 

 of those in Egypt, was one of the most difficult under consideration 

 at the present time. 



In reply to a question put by Mr. Whitaker, the Author remarked! 

 that there were undoubted differences in the Nubian Sandstone, 

 green shales being more abundant in its upper portion. The strata 

 alternating with the fossiliferous Cretaceous beds near Wadi Qena. 

 would, if found elsewhere, be unhesitatingly regarded as true 

 Nubian Sandstone. 



The Author thanked Dr. Smith Woodward for his remarks on the 

 Egyptian Eocene fishes exhibited, and pointed out that they were 

 kindly presented to the Cairo Geological Museum by Mr. Crawley, 

 head of the Technical Department in Cairo,, who also supplied notes 

 as to their supposed source of origin. 



"With regard to the general question of conformity and uncon- 

 formity, the results obtained required caution in deduction, the 

 Eocene and Cretaceous in the south showing more evidence 

 of conformity than was the case in the north. Nevertheless, 

 throughout Egypt the palseontological break was great, so far as the 

 Author's experience went. 



