222 CORALS AND CORAL ISLANDS. 



CHAPTER III. 



FORMATION OF OORAL REEFS AND ISL- 

 ANDS, AND CAUSES OF THEIR FEA- 

 TURES. 



I. FORMATION OF REEFS. 



I. ORIGIN OF CORAL SANDS AND THE REEF-ROCK. 



Very erroneous ideas prevail respecting the appearance of 

 a bed or area of growing corals. The submerged reef is 

 often thought of as an extended mass of coral, alive uniform- 

 ly over its upper surface, and as gradually enlarging upward 

 through this living growth ; and such preconceived views, 

 when ascertained to be erroneous by observation, have some- 

 times led to skepticism with regard to the zoophytic origin 

 of the reef rock. Nothing is wider from the truth : and this 

 must have been inferred from the descriptions already given. 

 Another glance at the coral plantation should be taken by 

 the reader, before proceeding with the explanations which 

 follow. 



Coral plantation and coral field are more appropriate ap- 

 pellations than coral garden, and convey a juster impression 

 of the surface of a growing reef. Like a spot of wild land, 

 covered in some parts, even over acres, with varied shrub- 

 bery, in other parts bearing only occasional tufts of vegeta- 

 tion in barren plains of sand, here a clump of saplings, and 

 there a carpet of variously-colored flowers in these barren 

 fields — sucb is the coral plantation. Numerous kinds of 

 zoophytes grow scattered over the surface, like vegetation 



