ALONG SHORE 



146 



to the shore when the tide is out, and pile them 

 over the tops of broken masts, sea-weed, and 

 rubbish, until they make a bank that may be a 

 barrier against the wave. Once a mound is 

 made it is held in place by the hardy grasses 

 and scrub-vegetation that grow on its sides 

 and top. The mound or bank may keep add- 

 ing to itself in this way until it stands a hun- 

 dred feet high along the coast, and makes an al- 

 most impregnable sea-wall. Behind such pro- 

 tection as these sand-dunes, and by the building 

 of dikes across the ocean inlets, thousands of 

 acres of water have been turned into green 

 pasture-lands and flat fields. Holland is an 

 illustration of it. 



There is still another way by which the land 

 gains upon the sea. The rivers, coming from 

 a great distance inland, flood drift and dirt 

 into the ocean. After a time the mouth of 

 the river begins to choke up with muddy de- 

 posits; a bar and then a bayou or lagoon is 

 formed, a marsh begins to rise above the waters, 

 seaweed accumulates, rushes and flags spring 

 into life and make the ground stable ; and 

 after many years a group of islands, or perhaps 

 a habitable meadow-land, is formed. Venice 

 was builded upon such a formation, caused by 



