34 The Great World's Farm 



them enormous quantities of rock, which is ground up bv 

 degrees into the finest mud and poured into the Nile. So 

 large is the amount of sediment brought down by the 

 river — which those who like statistics may be interested to 

 know is about equal in bulk to a solid cube measuring 

 more than five feet each way transported in every second — 

 that the river-bed is gradually rising, and the inundation 

 therefore extends further and further; and very, very 

 slowly, but still surely, more of the desert is being con- 

 verted into fruitful soil. Left upon the Abyssinian Moun- 

 tains, the materials of which this sediment is composed 

 would have had little or no value — for man's purposes, ai 

 least — but transported to the magnificent climate of 

 Egypt, and mixed with other matter, they form a soil 

 which is the very perfection of fertility. 



The sediment is not all deposited on the land or in the 

 river-bed, however; much is carried into the Mediterra- 

 nean, where another delta is being gradually formed, equal 

 no doubt to the old one in richness, and capable of bear- 

 ing crops as abundant, should it ever rise above the waters.. 

 A delta is possible only where there is little or no tide, or 

 current, to carry the sediment away. 



But it must not be forgotten that something more has 

 been done than merely to transport this wonderful soil. 

 It has also undergone much mixing, and consists not only 

 of mud washed from the Abyssinian Mountains, but of 

 sand, which is blown into the river in vast clouds from the 

 desert. The Nile itself, too, has done a great deal of 

 grinding, and sand and miud making, as well as its tribu- 

 taries. Sand, driven by water, will wear away the hardest 

 rock by degrees; and by means of the sand which the 

 wind blows into it, the river has cut its way through the 



