CH. XXVII THE SUBMARINE PLATEAU 



373 



miles seaward and form the platform, as is shown in the sections 

 on pages 62 and 107. 



We have in the great basaltic mountain of Seatura, which 

 forms the bulk of the western end of the island, a probable source 

 of many of these basaltic flows ; and the occurrence inland in 

 the western half of Vanua Levu of elevated table-lands of basalt 

 like that of Wainunu, which extend from the centre of the island 

 to near the coast, afford testimony that the formation of these 

 flows extends over a considerable period of the island's history. 

 / It is held by Professor Agassiz that these submarine platforms 

 are the work of erosion into the flanks of the up-heaved islands.^ 

 In Chapter II. it has been pointed out that the eroding agencies 

 are not actively in operation in our own day, and that there is 

 good reason for the belief that the process of amalgamation by 

 which Vanua Levu has been built up during a prolonged period 

 of emergence, is not suspended at the present time. It is assumed 

 that the uniformity in Nature's methods has not been broken. If, 

 however, we have here platforms of erosion, the coasts of Vanua 

 Levu, as far as my interpretation goes, supply no evidence of it ; 

 and we have to imagine that a period of emergence extending over 

 a geological age has been followed by a similarly vast period of 

 erosion without much change in level. 



Whatever agencies have been at work, the production of sub- 

 marine platforms 10 to 20 miles in width must have been a 

 stupendous operation ; and we shall be obliged to inquire whether 

 plateaux, either submarine or upheaved, occur in association with 

 volcanic islands in other parts of the world, and under what con- 

 ditions they have been formed. At least four hypotheses have 

 been framed with regard to the submarine platforms of Fiji. 

 There is first the original theory of subsidence of Darwin ; but 

 Vanua Levu, which presents one long story of emergence, offers 

 nothing to support this view. There is the growth of a reef sea- 

 ward on its own talus, as advanced by Murray. There is the theory 

 of erosion of Agassiz. There is lastly my own idea of basaltic 

 plateaux incrusted by reefs. We may therefore inquire as to the 

 evidence afforded by Vanua Levu in favour of these views. Basaltic 

 flows, in places covered by submarine deposits, form the low plains 

 at its sea-border, where the platforms are broadest ; and there 

 rises a basaltic mountain of the Mauna Loa type, occupying most 

 of the western end of the island. No one would be bold enough 



1 Tfie Islands and Coral Reefs of Fiji, Bull. Mus. Comp. Zool. Harv. Coll. 

 vol. 33, 1899. 



