i68 THE OCEAN 



trenched and fortified and there is less ap- 

 parent loss or gain by either side. 



Wherever the sea dashes upon a sandy 

 beach it pushes the sand before it and forms 

 piles or ridges of sand above high water mark. 

 As this dries the wind catches it in its grasp, 

 whirls it about and scatters it far and wide. 

 If the wind blows off shore the sand may be 

 carried out to sea where it sinks to the bottom 

 and forms sand bars, flats, or banks. In time 

 these bars or banks may form slender capes 

 or peninsulas which cut off a portion of the 

 sea, and this enclosed water may become grad- 

 ually filled with sand until no water remains, 

 and where the sea once held sway there will 

 be a broad level or hilly stretch of sand-dunes. 

 Even the sea itself may prove its own undoing 

 when it attacks a sandy shore, for the under- 

 tow of the waves often carries out sand and 

 mud which forms bars and flats and forces the 

 sea itself farther back. 



Wherever the wind whips up the sand and 

 blows it about it forms hills and hollows, often 

 building up dunes or hills many feet in height. 

 If these dunes are left undisturbed by strong 



