J. S, Gardiner — Origin of Coral Reefs. 203 



Art. XIX. — The Origin of Coral Reefs as shown ly the 

 Maldives ;^ by J. Stanley Gardiner, M.A. 



It was with very mixed feelin^js that I received some months 

 ago a request from the editor of this Jonriial, for some account 

 of my work on the formation of Coral Reefs, more particularly 

 as exemplified by the Maldive Group of islands. The ques- 

 tion involved is an extremely complicated one, especially since 

 the conditions in the various parts of the world where coral 

 reefs are found appear, superficially at least, to be widely differ- 

 ent. We have evidence in the fact of reefs, built by the same 

 lime-secreting organisms, actually occurring over broad areas 

 of the oceans, that the same animals and plants can adapt 

 themselves to the different conditions such as they are. At 

 the same time the reefs in widely separated areas of the 

 Pacific and Indian oceans, at any rate bear to one another a 

 remarkable family, even generic likeness, so that there would 

 seem to be certain factors of general occurrence. Indeed, it 

 would appear that we should look to such conditions as are 

 constant for an adequate explanation of the main features of 

 the topography of the existing reefs as w^ell as for an account 

 of their original formation. Premising the fact that it is 

 only profound knowledge and vast experience that can tell 

 how much of the present appearance of any set of reefs is 

 due to factors of universal distribution and how much is due 

 to purely local conditions, I pass to my more immediate sub- 

 ject, the origin of coral reefs. 



The question under consideration divides itself into two 

 chief heads, (1) the nature of the foundations on which the 

 lime-secreting organisms have built up their superstructure, 

 and (2) the mode of building and later history of their erec- 

 tions. My work of the past eight years in the Pacific Ocean 

 (Funafuti, Rotuma and the Fiji Islands) and in the Maldive 

 and Laccadive Groups, has dealt principally with the second of 

 these two heads, and in the latter islands can do no more than 

 throw an indirect light on the first question. Yet, a knowl- 

 edge of the physical conditions of the sea, and of their effects, 

 is not without importance in indicating the possible and even 

 probable methods of formation of these foundations. 



* For a full account of the Maldives see •' The Maldive and Laccadive 

 Groups with Notes on other Coral Formations in the Indian Ocean," Fauna 

 and Geography of the Maldive and Laccadive Archipelagoes, vol. i, pp. 12-50, 

 146-18B, 313-346, 376-423 (1901-3). 



The Maldive and Laccadive Groups lie to the southwest of India, extend- 

 ing in a broad belt almost from Bombay to lat. 1° S. Sufficiently good 

 charts for the purposes of this article will be found in Dana and Darwin's 

 well-known works on coral islands. 



Am. Jour. Sci.— Fourth Series, Vol. XVI, No. 93.— September, 1903. 

 14 



