174 THE OCEAN WORLD. 



heaped on the beach whence the tall cocoa-nut springs, plainly be- 

 speak the unrelenting power of the waves. Nor are any periods of 

 repose granted ; the long swell caused by the gentle but steady action 

 of the trade-winds, always blowing in one direction over a wide area, 

 causes breakers almost equalling in force those during a gale of wind 

 in the temperate regions, and which never cease to rage. It is impos- 

 sible to behold these waves without feeling a conviction that an island, 

 though built of the hardest rocks let it be porphyry, granite, or 

 quartz would ultimately yield and be demolished by such an irre- 

 sistible power. Yet these low, insignificant coral islets stand, and are 

 victorious ; for here another power, as an antagonist, takes part in the 

 contest. The organic forces separate the atoms of carbonate of lime, 

 one by one, from the foaming breakers, and unite them into a symme- 

 trical structure. Let the hurricane tear up its thousand huge frag- 

 ments, yet what will that tell against the accumulated labour of 

 myriads of architects at work night and day, month after month ? 

 Thus do we see the soft and gelatinous body of a polyp, through the 

 agency of the viial laws, conquering the great mechanical power of 

 the waves of an ocean which neither the art of man nor the inanimate 

 works of Nature could successfully resist." 



We have said that madreporic or coralline formations affect three 

 forms, to which the names of atolls, barrier reefs, and fringing reefs 

 have been applied. We have spoken of atolls ; we shall now say a 

 few words on barrier and fringing reefs. 



Barrier reefs are formations which surround the ordinary islands, or 

 stretch along their banks. They have the form and general structure 

 of atolls. Like atolls, the barrier reefs appear placed on the edge of a 

 marine precipice. They rise on the edge of a plateau which looks 

 down on a bottomless sea. On the coast of New Caledonia, only two 

 lengths of his ship from the reef, Captain Kent found no bottom in a 

 hundred and fifty fathoms. This was verified at Gambier Island in 

 the Pacific Ocean, in Qualem Island, and at many others. 



According to Mr. Darwin, the barrier reef situated on the western 

 coast of New Caledonia is four hundred miles long ; that along the 

 eastern coast of Australia extends almost without interruption for 

 a thousand miles, ranging from twenty or thirty to fifty or sixty miles 

 from the coast. As to the elevation of the islands thus surrounded 



