THE AFTER-HISTORY OF THE ATOLL 275 



quite separately, and the sedimentation spreads as a wave 

 across the lagoon, first killing the corals and then shallowing 



Fig. 67. 



Diagram to illustrate the Development of 

 Keeling Atoll. 



Stage IV. — The sand-bank completed and a part of it 



already made into an exposed bank by the action of the 



waves. 



the water by its own efforts. In time, this process 

 will spread across the whole area of the lagoon, and the 

 processes which have obliterated the secondary lagoonlets of the 

 horse-shoe-shaped islands will finally fill in the main lagoon. 

 This chain of events has of course already occurred in many 



