352 



FIRST YEAR SCIENCE 



Deltas have rich, fine-textured soils and are very fertile. 

 The Nile delta during all history has been noted for its 

 fertility. But they are treacherous places, as they are liable 

 to inundations by the overflowing of the river at time of 

 flood. Because they are pushed out into the sea, they 

 are peculiarly exposed to the sweep of the waves in great 

 storms. 



MOUTHS OF THE 



MISSISSIPPI RIVER 



The rate at which deltas grow depends upon the amount 

 of material carried by the river and upon the tides and 

 currents at its point of outlet. In seas where the currents 

 and tides are strong, no deltas are formed, except by very 

 large streams such as the Yukon, the Hoang-Ho and the 

 Ganges. In quiet seas deltas are readily built. The 

 delta of the Mississippi is more than 200 miles long and 

 has an area of more than 12,000 square miles. The Po in 



