176 



AGE OF CORAL REEFS. 



This demands some explanation, since I have 

 already said that no Coral growth can continue 

 after it has reached the line of high water. But 



§<* 



we have not finished the history of a Coral wall, 

 when we have followed it to the surface of the 

 ocean. It is true that its normal growth ceases 

 there, but already a process of partial decay lias 

 begun that insures its further increase. Here, 

 as elsewhere, destruction and construction go 

 hand in hand, and the materials broken or 



