290 Prof, J. W. Daicson— Geology of the Nile- Valley. 



I may remark here tliat in the vicinity of the Pyramids the great 

 succession of Eocene beds, 600 feet in thickness, which, in the 

 Mokattam hill, appears in a perfectly regular manner,^ has been so 



Fig. 1. Eaised Beach at Gizeh. 



a. Beach, b. Sand. c. Brown Limestone, d. Clay and Marl. e. Limestone. 



affected by lines of fault that some of the higher beds are brought 

 down to a comparatively low level, and consequently in the Het-el- 

 Orab a portion of the series which in the Mokattam is at a height of 

 at least 400 feet, descends to an altitude of about 160 feet above the 



Fig. 2. Mokattam Terraces from the Nile. 



sea-level. The throwing down in this way on the Lybian side of 

 the Nile valley in contrast with the comparatively undisturbed con- 

 dition of the beds on the Arabian side, has no doubt borne an 

 important part in determining the present position of the river. 



The side of the Het-el-Orab next the Pyramids presents a vertical 

 quarried face, with a slope of debris below and at top some beds of 

 marl and gypseous clays, surmounted by coarse limestone containing 

 Upper Eocene fossils, for the identification of which I am indebted 

 to Dr. Schweinfurth. On the opposite, or south-east side, the hill is 

 in its natural state, and shows a sea-worn cliff, in which the upper 

 hard beds have been partially let down and disturbed by the under- 

 cutting of the marls and clays beneath them. Here the edges of the 

 limestone have been perforated with Lithodomi, and are covered with 

 oyster shells, often showing both valves in contact, and better grown 

 than those in the locality of the Mokattam. There are also a few 



^ Schweinfurth, Proc. German Geol. Survey, 1883. 



