IN THE OOCOS-KEELING ISLANDS. 35 



CHAPTER III. 



SOJOUEN IN THE COCOS-KEELING ISLASDS— continued. 



Coral reef formation — Observations on the elevation or subsidence of the 



Keeling atoll. 



As the Keeling atoll was the reef most carefully examined and 

 described by Mr. Darwin, and that with which, in propounding 

 his famous theory of coral reefs, he has compared the others he 

 describes, I felt specially pleased at being able to go over 

 his own ground with his book in my hand, and gain a clearer 

 understanding of several points which I had foimd it difficult 

 to comprehend. 



Unfortunately the weather during my visit was not suffi- 

 ciently favourable to enable me to examine so closely as I 

 could have desired the corals of the outer margins or to make 

 the series of seaward soundings I had intended. 



The first questions that present themselves to the traveller 

 in midst of his amazement on first reaching that peculiar 

 production of the warm seas — an island-speckled ring of coral 

 holding its own against the waves— are, How came it into being 

 here, Why of this singular form, and How does it continue to 

 exist ? Mr. Darwin was the first to attempt any far-reaching 

 solution of these difficult questions, applicable to coral forma- 

 tions over all the world. As true reef-building corals, it is well 

 known, can flourish only beneath a very limited depth— some 

 twenty fathoms — of water, a great apparent difficulty existed 

 " respecting the foundations on which these atolls are based, 

 from the immensity of the spaces over which they are inter- 

 spersed and the apparent necessity for believing that they are 

 all supported on mountain summits, which, although rising very 

 near to the surface of the sea, in no one instance emerge above it. 

 To escape this latter most improbable admission, which implies 

 the existence of submarine chains of mountains of almost the 



