FORMATION OF CORAL REEFS AND ISLANDS. 193 



We must, therefore, allow that some effect will be produced 

 upon the coral groves. There will be trees prostrated by gales, 

 as on land, fragments scattered, and fragmentary and sand 

 accumulations commenced. Besides, masses of the heavier 

 corals will be uptorn, and carried along over the coral planta- 

 tion, which will destroy and grind down everything in their 

 way. So many are the accidents of this kind to which 

 zoophytes appear to be exposed, that we might believe they 

 would often be exterminated, were they not singularly tena- 

 cious of life, and ready to sprout anew on any rock where 

 they may find quiet long enough to give themselves again a 

 firm attachment. 



But it should be observed, that the sea would have far 

 lesy effect upon the slender forms characterizing many zoo- 

 phytes, among which the water finds free passage, than on the 

 massive rock, against whose sides a large volume may drive 

 unbroken. Moreover, much the greater part of the strength 

 of the ocean is exerted near tide level, where it rises in 

 breakers w^hich plunge against the shores. Yet owing to the 

 many nooks and recesses deep among the corals, the rapidly 

 moving waters, during the heavier swells, must produce whirl- 

 ing eddies of considerable force, tending to uproot or break 

 the coral clumps. These disrupting and transporting effects 

 will be less and less as we recede from the shores ; yet all 

 coral depths must experience them in some degree. 



There is another process going on over the coral field, 

 somewhat analogous to vegetable decay, though still very 

 different. Zoophytes have been described as ever dying while 

 living. The dead portions have the surface much smoothed, 

 or deprived of the roughening points which belong to the 

 living coral, and the cells are sometimes half obliterated, or 

 the delicate lamellae worn away. This may be viewed as one 

 source of fine coral particles ; and as the process is constantly 

 going on, it is not altogether unimportant. This material is in 

 a fit condition to enter into solution, and it cannot be doubted 

 that the water receives lime from this source, which is afterward 

 yielded to the reef. 



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