136 CORAL AND ATOLLS 



we tend to divorce the study of the structures raised by the 

 zooids from the study of the zooids themselves, the less will 

 we tend to approach their true solution. 



The subject-matter of these chapters may be taken as 

 representing the outcome of a somewhat prolonged series 

 of personal observations, made upon the living, growing reef, 

 that supports one of the most perfect atolls that is in 

 existence. 



Lest my practical knowledge of coral formations should 

 rest only upon the examination of a perfected atoll, I embraced 

 the opportunity, afforded by the kindness of Captain Maclear 

 Ladds, of the Singapore Pilot Service, of examining the many 

 reefs and coral structures that lie in the neighbourhood of 

 Singapore ; — and I was further enabled to examine, though 

 in no great detail, coral structures that fringe the shores of 

 Sumatra, Java, Sumbawa, and the other Malayan Islands ; — 

 and finally to make the double journey of the whole extent of 

 the Great Barrier Keef of Australia. 



I was early convinced that " Subsidence " will not explain 

 the development of all coral formations ; and that " Solution " 

 will certainly explain still less ; — and, in the explanation that 

 I would advocate, the chief agent is one that acts upon the 

 living colony — and is " Sedimentation." 



I am well aware that the harmful effects of Sedimentation 

 have received previous attention, but I would extend their 

 action, and I would make them by far the most important 

 agents in producing all the forms of coral structures as we find 

 them to-day. 



The processes of Sedimentation which have been followed 

 in their action upon the colony will therefore be studied as 

 they are to be seen displayed upon a grander scale. It has 

 been demonstrated how the harmful action of Sedimentation 

 can produce an atoll-shaped rock a few feet in diameter, 

 and it is logical to inquire if an atoll like Cocos-Keeling, 

 whose lagoon is several miles across, might be produced in 

 the same fashion. The atoll as a whole must therefore be 

 examined. 



