48 SEA AND LAND 



once become riKle, and, when first and imperfectly seen, 

 apparently shapeless. 



We commonly find on pebbly beaches a rude wall of 

 water-worn stones, rising", it may be, ten feet or more above 

 hii^di tide. This wall sweeps around the crescent of the true 

 beach, fojlowinj^; its course from one end to the other, looking 

 often like an artificial rampart. Now and then it is deeply 

 breached or sometimes for a considerable distance swept away. 

 The oriein of this beach-wall is simple : in times of unusually 

 heavy storms blowinc^ directly upon the coast, especially when 

 they fall in the season of the hiohest tides, the waves tres- 

 pass upon the upper part of the shore and fling a great 

 (luantity of pebbles before their swift-moving front ; wdien 

 the on-rushing surge conveys these pebbles beyond the sea- 

 ward face of the beach to the crest of its wall, they fall upon 

 the more level summit, and the retreating waters cannot drag 

 them back into the sea. When the ocean is in its stormiest 

 condition, the pebbles may be tossed over the crest of the 

 embankment and fall down its landward slope. If the seas 

 struck the shore in a uniform manner, this wall would have 

 a perfectly regular height ; but now and then, in great tem- 

 pests, there comes a vast wave, which has gathered unto itself 

 the strength of several breakers, and which may assail a part 

 of the sea-wall with such fur\', that it breaks it away and 

 sends the debris into a steej), delta-like fan out upon the low- 

 land Ixhind the elevation. Subsequent waves, which may be 

 of less volume, pour through and deepen the breach, so that 

 the wall acquires its crenellated or battlemented aspect. The 

 open structure of the pebbly mass allows the swash of the 

 wave to penetrate downward and escape slowly to the sea, 

 so that the retiring water is diminished in volume, and its 



