The Mighty Deep 



may be seen. These are a common feature of 

 river-mouths. 



Many a larger river has at its mouth an 

 enormous network of banks, divided by streams, 

 and the whole is described as the " delta" of 

 that river ; its shape being roughly like the 

 Greek letter " delta," or like an opened fan. 

 Everybody has heard of the Delta of the Nile, 

 the Delta of the Ganges, the Delta of the 

 Mississippi. But hardly a river exists, no matter 

 how small, which on joining the sea does not 

 make its own little delta. 



And the formation of these deltas comes about 

 in a very simple manner. 



So long as a river flows onward, at a fair pace, 

 it is able to hold up its floating materials, to keep 

 the earth and sand in its embrace from sinking 

 to the bottom. But when it reaches the sea, 

 its progress is checked ; and no sooner does it 

 slacken speed, than some of its buoyed-up 

 materials begin to sink. The heavier kinds are 

 the first to touch bottom, getting piled up so 

 as to form a bar or bank ; and farther out, as 

 the stream grows yet more slow, lighter sub- 

 stances find their way downward, making another 

 bank. 



In fact, the river, with Ocean's help, is busily 

 106 



