Vol. 67.] 



EASTERN DESERT OF EGYPT. 



247 



one climbs the gully, the sand becomes finer and less firm, until it 

 is so fine and loose that one sinks up to the knees in it. The equi- 

 librium of the mass is very unstable, the slightest jarring causing 

 great masses to slide much like a fluid towards the bottom. 



Fig. 3 



Foraminiferal sand, with abundance of Orbitolites com- 

 planata Lam. and other organisms. Southern shore of South 

 Gaysum Island. (Natural size.) 



The sands which occur among the gravels in the depression 

 between the Zeit range and the Um-Esh range are of a peculiar 

 character. Very little fine sand occurs, but grains as large as 

 peas, usually 5 to 10 millimetres in diameter, cover large areas 

 in such a manner as to appear as though they had been artificially 

 set. A careful examination of the individual grains showed that 



