PROTECTIVE EFFECT OF SAND-BEACHES 7Z 



can stand a year of steady thrashin^^ on the shore, but these 

 sands endure for ages. The reasons for this are simple. In 

 the first phice, each grain of sand is an admirable illustration 

 of the principle of the survival of the fittest. If it be not 

 perfectly coherent and very hard, it will not be carried far 

 before its weakness is found out and it is broken into mud 

 on the pebble-beaches, where it is generally made and borne 

 away by the sea to the deeper water. Then, because of their 

 smallness, the grains lie with so little interspaces between 

 them that they hold the water next their faces by capillary 

 attraction. When a wave strikes the shore the grains of sand 

 are pounded together, but they do not touch each other. If 

 we press on the wet sand with the foot we see that the mass 

 whitens as the pressure is applied and a part of the intersti- 

 tial water is poured out : take the foot away, and the water 

 returns to the crevices between the grains. Only dry sand 

 will rub, grain against grain, and give the audible sound 

 which when it is sharp and clear is called singing. No 

 beach will thus creak or sing beneath the feet when it is 

 wet. 



This curious endurance of rocky matter, in its comminuted 

 form, to the erosive force of the sea, makes the sand the 

 natural protector of the land against the fierce assaults of 

 the sea. If sand were easily pulverized, if it were readily 

 floated away, if it had, indeed, any other than its actual 

 assemblage of properties, it is doubtful if the lands could 

 have made good their place in the contest with the ocean. 

 These doughty little champions have certainly kept for our 

 use empires which but for their good work would long ago 

 have vanished beneath the waves. Thus a process which 

 begins with swift wasting of the land on the exposed cliffs of 



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