1898.] Funafuti, Rotuma and Fiji. 491 



extension of its talus slope he does not say. The sections of the 

 sea bottom off Masamarhu Island 1 in the Red Sea can only, I hold, 

 be taken as indicating sudden and rapid subsidences. 



The limestones 4,000 to 6,000 feet thick mentioned by Dana 2 , 

 with similar fossils from top to bottom, afford no evidence to show 

 that there have been to form them " slowly progressing sub- 

 sidences" of 4,000 to 6,000 feet. I do not contend that these have 

 not been formed by subsidence, or that the subsidence was not 

 a slowly progressing one, but I do protest against the too rapid 

 conclusions, which fix at once the nature of the bottom, and the 

 depth at which the organisms lived, without allowing them any 

 power to adapt themselves to changed surroundings and con- 

 ditions of life. An absolutely vertical thickness of coral limestone 

 of more than the 1000 feet of Vatu Vara has, as far as I know, not 

 yet been proved; the real thickness to the volcanic rock indeed 

 may be considerably less. Dana and others do not show of what 

 constituents the raised limestone ' reefs are formed. Hence it is 

 purely an assumption to suppose that the whole thickness of any 

 of these raised reefs has been formed mainly of coral in the way 

 which the subsidence theory requires ; there is no more evidence 

 that their lower parts are formed in this way than, for instance, 

 that they are formed by the fragments of a talus slope, which 

 have been consolidated together. 



Dana explains the absence of fringing reefs and shoals inside 

 barrier reefs on the supposition that the conditions are much more 

 favourable for the latter than the former. " If the barrier in- 

 creases one foot in height in a century, the inner reef, according 

 to this supposition, would increase but half a foot ; and any rate 

 of subsidence between the two mentioned, would sink the inner 

 reefs more rapidly than they could grow and cause them to 

 disappear 3 ." According to Dana's view, as already mentioned, 

 the Fiji Group forms an area, where subsidence is still going on. 

 It must be remembered, however, that in Fiji the land is fringed 

 with a reef inside the lagoons of barrier reefs, where the island 

 has a broad stretch of water between the barrier and itself. The 

 great luxuriance of the reef east of Wakaya and the volcanic part 

 of Vanua Mbalavu is very noticeable, and yet on the subsidence 

 continuing both of these are to disappear. Coral grows in the 

 localities I have visited far more luxuriantly inside the lagoon 

 than where the reef is exposed to the full force of the ocean. 

 Bourne remarked on the rich growth in the lagoon of Diego 

 Garcia, in positions where sand is not deposited, and at Funafuti 

 it was apparent to all the members of the first expedition 



1 Nature, xxxvi., p. 413. 



2 Loc. cit., p. 278. 



:i Dana, loc. cit., p. 265. 



