CORAL REEFS 



169 



rock called oolite, which is made up of minute spherules of CaC0 3 

 cemented into a mass not unlike fish-roe in appearance. This is 

 due to the deposition of CaC0 3 from solution around tiny grains 



Fig. 68. — Various forms of modern coral limestone. (Savile Kent.) 



of calcareous sand, until the spherules are built up and cemented 

 together. 



The growth of coral ceases when the reef extends up to low- 

 water mark, but the waves continue their work and throw up debris 

 and build up a platform, upon which they establish a beach of 



