ACTION OF THE SURF 43 



from a wind which blows directly upon the shore, or from 

 some storm in the open sea so far away that the ground-swell 

 alone attests its passage over the waters. These waves may 

 roll upon the beach with a height of from five to ten feet, 

 and at the rate of from four to six strokes a minute, each 

 blow applying to the shore-line in a mile of its length energy 

 which is to be measured by thousands of horse-power. These 

 surges break or overturn, not at the very shore-line, but at a 

 distance from the dry sands determined b}' their altitude and 

 the shape of the beach. On ordinary fronts of sand they 

 tumble into surf-waves, a hundred yards or more from the 

 point where we may stand dry-shod, and on many parts of 

 the coast they break at a mile or more from the water-line. 

 Within the outer line of surf the waves gather again and 

 again to form lesser breakers, so that there is a wide belt of 

 tumbling water extending, it may be, for hundreds of miles 

 along the coast. 



Next the shore this turmoil of the sea is marked by fierce 

 splashings arising from the overturning waves ; the water 

 rushes up and down the steeper slope of the inner part of 

 the beach, sweeping the coarse sand and pebbles before it in 

 each movement, it may be for sixty feet or more. If the 

 pebbles are abundant, we can easily hear the dull, grating 

 sound arising from the friction of the stones against each 

 other as they are driven to and fro. Standing with bared 

 feet in this splash, we easil)- note the fact that it is not only 

 the surface of the beach which is moved, but the mass, to the 

 depth of perhaps a foot or more, partakes of the movement 

 which the surging waters impress upon it. The stones are 

 orround against each other, and the sand amono- them pulver- 

 ized as if between mill-stones. The result is that at each 



