



1 



'^IHhk> 



¥ 



^ 



*Mtf 



» 



Htne r- 



1". 





* yards ..:je i 



'■ : ^ the blue 



'^ u u; r '^:: 



A 



hich is 



encff' 



} 



! wBicli aie 

 anci beach en- 



aT 



ertical sun. 

 where 



r innneibk 

 , Vo periods 



) 





• 9 



dd^ 



1. 



^ex 



[it 





. „ f ro«l^' 



D 



bede 



moH 





1^ 



as 



by 



u.ll 



( 



f liflJ^ ^ 



^!ie 



■ F 



4 



W 





Ch. XLIX.] 



EEEFS CONVEETED INTO ISLANDS. 



587 



^ ^ 



corals leave off building. 



one from the foaming breakers^ and unite tliem into a sym- 

 metrical structure ; myriads of architects are at work night 

 and day, month after month^ and we see their soft and gela- 

 tinous bodies through the agency of the vital 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. 



As the coral animals require to be continually immersed in 

 salt water, they cannot raise themselves by their own efforts 

 above the level of the lowest tides. The manner in which 

 the reefs are converted into islands above the level of the sea 

 is thus described by Chamisso, a naturalist who accompanied 

 Kotzebue in his voyages: — *^When the reef/ says he, 'is of 

 such a height that it remains almost dry at low water, the 



Above this line a continuous mass 

 of solid stone is seen composed of the shells of moUusks and 

 echini, with their broken-off prickles and fragments of coral^ 

 united by calcareous sand, produced by the pulverisation of 

 shells. The heat of the sun often penetrates the mass of 

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

 force of the waves is thereby enabled to separate and lift 

 blocks of coral, frequently six feet long and three or four in 

 thickness, and throw them upon the reef, by which means 

 the ridge becomes at length so high that it is covered only 

 during some seasons of the year by the spring tides. 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 rapidly grow, to overshadow its dazzling white 

 surface. Entire trunks of trees, which are carried by the 

 rivers from other countries and islands, find here, at length, 

 a resting-place after their long wanderings : with these come 

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

 inhabitants. Even before the trees form a w^ood, the sea- 

 birds nestle here ; stray land-birds take refuge in the bushes ; 

 and, at a much later period, when the work has been long 



since completed, man appears and builds his hut on the 

 fruitful soil.' f 



^^ Darwin's Journal, &c., pp. 547; 548, and 2nd edit., of 1845, p. 460. 

 t Kotzebue's Voy., 1815-18, vol. iii. pp. 331-333. 



