Islands and Coral-reefs of the Fiji Group. 241 



Fiji ; so that the great depth of the lagoons of some of the 

 atolls can no longer be considered as a proof of the theory of 

 subsidence. 



Fulanga is also interesting as illustrating the formation of 

 an atoll by the same causes which have produced tlie Sounds 

 in the Bermudas. In the case of Fulanga we have a volcanic 

 summit which has raised the elevated coral-reef forming its 

 rim to a height of probably 200 feet. This coral rim has 

 been broken through, and the action of the sea has gradually 

 hollowed out in the interior a circular sound resembling a 

 crater, which is due solely to the disintegration of the inner 

 parts of the elevated reef. In the interior and outer edge of 

 the Sound of Fulanga many parts of this reef still exist as 

 small mushroom-shaped islands or small rounded or conical 

 hills. It is also probable that some of the elevated reef-flats 

 forming the rims of atolls owe their origin to causes similar 

 to those which have shaped the crater-like Sound of Fulanga. 

 This has perhaps been the case with such atolls as Ngele 

 Levu, the Oneata, Ongea, and Yangasa clusters and others. 



The great variety of causes which have been active in 

 shaping the present physiognomy of the reefs and atolls of 

 Fiji shows the impossibility of assigning any one factor, like 

 subsidence for instance, as is done by Dana and Darwin, as 

 the single cause for the formation of the many different kinds 

 of atolls and barrier-reef islands to be found in the Fiji group. 

 The formation of the great barrier reef of the southern shores 

 of Viti Levu is due to causes very similar to those which have 

 given to the northern coast of Cuba between Nuevitas and 

 Matanzas its present physiognomy. Along those parts of 

 the island where denudation and erosion proceed rapidly, 

 owing to the soft character of the shore-rocks, very extensive 

 flats have been formed, as those south of Ovalau. When 

 the reef-barrier flats have been eroded from a harder base, 

 like volcanic rocks, the flats are less prominent and some- 

 what more extensive than when the old elevated coral-reef 

 formed the shore-hills; or the reef-flats may disappear altogether 

 when the harder volcanic rocks have been only little affected 

 by erosion or denudation. From the nature of the ne^-ro- 

 heads scattered upon the reef-flats it is generally a simple 

 matter to ascertain the character of the base of the reef-flafs 

 of an atoll or of a barrier reef. 



We were fortunate in being at Levuka at the time of the 

 appearance of the " Bololo." On the morning of the 17th of 

 November we left the ship at 3 o'clock, bound for a spot 

 named " Bololo " Point, about 3 miles south of Levuka. We 

 had scarcely reached the spot when our guide tished up a ^qw 



