BY W. G. WOOLNOUGH. 485 



determine. Then came an extensive elevation by which the 

 formations were brought above sea-level, plicated, metamor- 

 phosed, and weathered. This period, too, must have extended 

 over an enormous time during which the land was denuded to 

 its very roots so that plutonic masses of granite and quartz 

 diorite were laid bare. Most of the sedimentary formations 

 were completely swept away. Then probably followed the separa- 

 tion of the outlier from the main continent. An extensive sub- 

 sidence of the Fijian area to the extent of at least 1300 feet then 

 took place, as is proved by the occurrence of fossiliferous tuffs at 

 Drau (1290 feet) and Nosoqo (800 feet). At the latter place the 

 shells are associated with a tuffaceous conglomerate containing 

 large water-worn granite pebbles (up to 4 inches in diameter), 

 and therefore probably of the nature of a basal (?) conglomerate. 

 Since then there has been an oscillation in the sea-level, but on 

 the whole with a tendency towards positive motion of the land. 

 Andrews has shown that this elevation is very marked in the 

 islands of the Lau Group, viz., Cikobia-i-ra 630 ft., Tuvuca 800 ft., 

 Vatu Vara 1050 ft., and Yacata 840 ft. In the Yasawas an 

 elevation of 800 feet is recorded. 



vii. — Comparisons and Conclusions. 



From the fact that rocks such as granite, diorite, and other 

 plutonic eruptive rocks, and sedimentary formations such as 

 schists and slates occur, with few exceptions, only on continents 

 or on islands whose geological connection with continents is 

 obvious, the theory of the "Permanence of Ocean Basins and 

 Continental Areas " has arisen. This theory is still further 

 supported by the fact that, with a few exceptions, islands rising 

 from great ocean depths are composed of volcanic rock, organi- 

 cally formed limestone, or a mixture of the two, like Christmas 

 Island in the Indian Ocean. 



The special interest which attaches to the geology of Fiji 

 arises from the fact that it is one of the most marked, if not the 

 most marked, exception to the rule above stated. Of the neigh- 

 bouring islands to the east, Eua in the Tonga group is the only 

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