ORIGIN OF CORAL REEFS 



' The analogy to vegetation does not stop here. It is 

 well known that the debris of the forest, decaying leaves 

 and stems, and animal remains, add to the soil ; that in 

 the marsh or swamp where decaying vegetation is mostly 

 under water, and sphagnous mosses grow luxuriantly, 

 ever alive and flourishing at top, while dead and dying 

 below accumulations of such debris are ceaselessly in 

 progress, and deep beds of peat are formed. Similar is 

 the history of the coral mead. Accumulations of frag- 

 ments and sand from the coral zoophytes growing over 

 the reef-grounds, and of shells and other relics of organic 

 life, are constantly making ; and thus a bed of coral debris 

 is formed and compacted. There is this difference, that 

 a large part of the vegetable material consists of elements 

 which escape as gases on decomposition, so that there is 

 a great loss in bulk of the gathered mass ; whereas coral 

 is an enduring rock material undergoing no change except 

 the mechanical one of comminution. The animal portion 

 is but a mere fraction of the whole zoophyte. The coral 

 debris and shells fill up the intervals between the coral 

 patches, and the cavities among the living tufts, and in 

 this manner produce the reef deposit; and the bed is 

 finally consolidated, while still beneath the water. 



' The coral zoophyte is especially adapted for such a 

 mode of reef-making. Were the nourishment drawn 

 from below, as in most plants, the solidifying coral rock 

 would soon destroy all life : instead of this, the zoophyte 

 is gradually dying below while growing above ; and the 

 accumulations of debris cover only the dead portions. 



" But on land there is the decay of the year, and that 

 of old age, producing vegetable debris; and storms pros- 

 trate forests. And are there corresponding effects among 

 the groves of the sea ? It has been shown that coral 

 plantations, from which reefs proceed, do not grow in the 

 ' calm and still ' depths of the ocean. They are to be 

 found amid the very waves, and extend but little below 

 a hundred feet, which is far within the reach of the sea's 

 heavier commotions. To a considerable extent they 

 grow in the very face of the tremendous breakers that 

 strike and batter as they drive over the reefs. Here is 

 an agent which is not without its effects. The enormous 

 masses of uptorn rock found on many of the islands may 

 give some idea of the force of the lifting wave ; and there 



215 



