58 



SEA AND LAND 



of water which are impelled by the extremely varied currents 

 which the irregular falling of the surf and the inequalities of 

 the bottom bring about. If the beach is smooth when these 

 tongues of water begin to sweep up its slope, they at once 

 carve out shallow, indistinct grooves. The very front of the 



Heavy Surges on Beach Shore 



Showing succes-ive lines of advancing breakers and the process of retreat of a surge which has broken 

 upon the shore. The parallel lines on the strand represent the swash swiftly flowing down the slope, 

 dragging the sands and pebbles with it. 



swash-flow makes the beginnina- of an indentation, and each 

 successive movement extends the depression. In the middle 

 of the re-entrant the current is strongest, because it has 

 the freest play ; in the rellux movement it scours out the 

 debris which on the sides is left untouched ; and, indeed. 



