162 CORAL AND ATOLLS 



under the shelter of rocks that corals can retain a foothold at 

 all, and the picture of the active corals flourishing in the crash 

 and swirl of the breakers is not a true one. We have seen 

 that, as the barrier in between the islands is followed into the 

 lagoon, the coral growth becomes more abundant ; and again 

 in the ocean, outside the surf-beaten edge, the active living 

 coral growth increases, and in the six fathoms or so in which 

 it is possible to see them clearly, large masses surpassing 

 anything on the barrier, or in the lagoon, flourish on the 

 submarine slopes. 



Although living coral forms so small a portion of the 

 actual barrier, still there is no part of the barrier that is not 

 made of coral, but it is the dead and altered remains of past 

 generations. The idea is common regarding the building of 

 coral islands, that the coral grows and grows, and as it dies it 

 forms the basis of the island ; that in fact the coral is ever 

 growing up, and the calcified part in time reaches to such a 

 level that dry land is formed in the midst of the ocean. This 

 of course does not, and cannot, happen. The barrier has not 

 grown up by the growth of coral in situ, and the island has 

 not come into existence through the direct activity of coral 

 growth. Even those few living corals on the barrier are for 

 the most part waifs and strays, living Avhere they do because 

 they have been washed there, and, as is their wont, have 

 fixed themselves to the first safe anchorage that comes to 

 hand. In the coral beds which lie on the submarine slopes of 

 the atoll ridge large masses of Porites, and other forms, are 

 ever growing in great profusion, and the rock is being slowly 

 built up which will one day, during storm, be moved from its 

 bed, lifted by the swell, and hurled shorewards by the surf. 

 Many large masses are no more than lifted from their beds, and 

 left to stand as outguards of the barrier, their sides becoming the 

 site of further coral growth so that in time they become 

 cemented in their place by the growth of the hardier species 

 of barrier corals. Smaller masses are trundled farther toward 

 the shore, and a belt of coral wreckage is deposited from the 

 low-water surf-line of spring tides, to the high-water line of 



