376 THE WORK OF RUNNING WATER 



Jersey coast marsh plants abound and serve as a shield against 

 waves ; in addition they entrap and entangle sediment washed 

 in by waves, and thus they add to the shore. In Florida man- 

 grove trees protect the coast (Fig. 244). 



Plants are one of the best means of protection against stream 

 erosion. Slopes covered with vegetation do not have their 

 fertile soil washed away by the rain. The soil in which plants 

 grow is kept open and loose by the growing roots and quickly 

 absorbs water which falls on it ; thus water which would have 

 been carried away, is itself entrapped and held fast. Then, 

 too, roots act as nets to the soil and prevent its escape ; land- 

 slides seldom occur on thickly wooded slopes, but occur fre- 

 quently on barren hillsides. Cultivation of plants on hillsides 

 and along streams is one of the simplest and surest methods of 

 preventing loss of land. 



