CORAL ISLANDS. 385 



dium of the cementing calcareous sand, which has arisen 

 from the pulverization of the above mentioned shells into 

 one whole or solid stone, which, strengthened by the con- 

 tinual throwing up of new materials, gradually increases 

 in thickness till it at last becomes so high, that it is cover- 

 ed only during some seasons of the year by the high 

 tides. The heat of the sun so penetrates the mass of 

 stone when it is dry, that it splits in many places, and 

 breaks of in flakes. These flakes, so separated, are rais- 

 ed one upon another by the waves at the time of high 

 water. The always active surf throws blocks of coral, 

 (frequently of a fathom in length, and three or four feet 

 thick,) and shells of marine animals, between and upon 

 the foundation stones ; after this the calcareous sand lies 

 undisturbed, and offers to the seeds of trees and plants, 

 cast upon it by the waves, a soil upon which they rapid- 

 ly grow, to overshadow its dazzling white surface. En- 

 tire trunks of trees, which are carried by the rivers from 

 other countries and islands, find here, at length, a rest- 

 ing place after their long wanderings ; with them come 

 some small animals, such as lizards and insects, as the 

 first inhabitants. Even before the trees form a wood, 

 the real sea-birds nestle here ; strayed land-birds take re- 

 fuge in the bushes ; and at a much later period, when 

 the work has been long since completed, man also ap- 

 pears, builds his hut on the fruitful soil formed by the 

 corruption of the leaves of the trees, and calls himself 

 lord and proprietor of this new creation. 



In the preceding account, we have seen how the exte- 

 rior edge of a submarine coral edifice first approaches 

 the surface- of the water, and how this reef gradually as- 

 sumes the properties of land ; the island, therefore, ne- 

 cessarily has a circular form, and in the middle of it an 



B b 



