44 



changes had taken place in organic life due partly to the migra- 

 tions caused by such changing conditions as the increasing depth, 

 of the sea and the increasing purity of its waters. That was in 

 brief, and without the qualifications that' he would have liked to- 

 introduce, if time had permitted, the story of Egypt, and not 

 only of Egypt but also of a large part of North Africa and Arabia, 

 during the time that the chalk was accumulating in England. 



At the close of the Cretaceous period important changes took 

 place both in organ'c life and in physical geography, and different 

 parts of Egypt were affected differently. In the south the Lower 

 Eocene rocks appeared to have succeeded the Cretaceous rocks- 

 witnout a break, but in the north the latter had been folded, 

 faulted, raised above sea level, and portions of them removed 

 by denudation before the Middle Eocene rocks were deposited 1 

 upon them. The passage from Eocene to Oligocene times was 

 marked by a gradual transition from marine to terrestrial condi- 

 tions, and in the transitional deposits a remarkable assemblage of 

 animal remains, including the ancestors of the elephant and 

 mastodon had been found. Sea once more overspread the land 

 in Miocene times. 



The President then proceeded to describe the physical features 

 of the Nile valley from the second Cataract to Cairo, illustrating 

 his remarks by a series of lantern slides. He showed that at the 

 second cataract the flow of the river is interrupted by innumerable 

 islands of diorite and other rocks belonging to the old floor, that 

 the country on both sides of the river is formed of the littoral 

 deposits of the Upper Cretaceous period — the Nubian Sandstone 

 — and that these deposits rest unconformably on the rocks of the 

 old floor. He pointed out that, below the Cataract, the river- 

 flows uninterruptedly in a broad stream between banks of 

 alluvium backed by a dissected plateau of Nubian sandstone; 

 that the strat ification was nearly horizontal ; that out of this great 

 rock sheet hills had been sculptured, manly by the action of the 

 wind ; that the hills sometimes possessed the form of table moun- 

 tains, sometimes that of isolated pyramids, and that between these 

 two types every intermediate form could be observed. Referring 

 to the" table mountain landscape, as it is sometimes called, he said 

 ' We are thus able to picture in imagination the process by which 

 a plateau may, in the course of ages, be destroyed. We see, as 

 it were, the process going on before our eyes. First a plateau, 

 then table-mountains, then truncated pyramids whose summits 

 reach the level of the old plateau, then lower pyramids, then 

 mounds, and finally a plain corresponding to the base level of 

 erosion." 



" The hills are shadows, and they flow 



From form to form, and nothing stands ; 

 They melt like mist, the solid lands. 

 Like clouds they shape themselves and go." 



