276 CORAL AND ATOLLS 



atolls, and Pulu Luar in this group is an example of tlie final 

 stage of atoll-making — a stage in which a rim of slightly 



Fig. 68. 



Diagram to illustrate the Development of 



Keeling Atoll. 



Stage Y. — The final stage, in which a large area of 



leeward land is formed, and the only inlet to the lagoon is 



to the windward. The inlet is guarded by a barrier and 



to the lee side of the atoll no barrier is developed. 



raised land surrounds a central basin, wholly or partly dry at 

 all states of the tide. 



We have followed the fate of the sand that becomes cast 

 upon the land, and of that which becomes deposited in the 

 lagoon, but this by no means represents the whole of the 



