Islands and Coral-reefs of the Fiji Group. 235 



elevated coral-bluffs are very much lo\Ter, those of Malatta 

 and Susni reaching a height of a little over 400 feet. Goino* 

 farther west and south we find at Mango the vertical bluffs of 

 an elevated coral-reef of over 600 feet, and underlaid bj 

 volcanic rocks which crop out at the sea-level. 



At Tavutha the coral-limestone bluffs are probably 800 feet 

 high. At Naiau they are over 500 feet, at Lakemba they 

 reach a height of about 250 feet on the south-west side of the 

 island ; the rest of the island is volcanic. On the island of 

 Aiwa the elevated reef is fully 200 feet thick. In the Oneata 

 group the higliest point of the elevated reef-bluffs is about 

 160 feet. South of the volcanic island of Motha and enclosed 

 within the same barrier reef on the island of Karoni the 

 elevated reef is about 120 feet thick. On the three islands of 

 the Yangasa group it attains a thickness varying between 240 

 and 390 feet, and^ finally, on Ougea, the most south-easterly 

 cluster we visited, the elevated reef attains a thickness of 

 nearly 300 feet. At Fulanga the elevated reef attains a 

 thickness of 360 feet, at Kambara it is about 200 feet thick, 

 and at Wangawa it is perhaps over 300 feet : these islands 

 are in part volcanic. Finally, at Vatu Leile, the most 

 westerly island we examined, the elevated reef forming the 

 island is 110 feet tliick at its northern extremity. 



All this plainly shows that the southern part of Viti Levu 

 and as far south as Vatu Leile, and the wiiole length of the 

 windvvard islands of the Fiji group from Ngele Levu on the 

 north to Ongea on the south, have been subject to an eleva- 

 tion of at least 800 feet, as there is abundant proof that a 

 great part of the thickness of tiie elevated reef has been eroded 

 to reduce it in certain localities to the level of the sea or to 

 leave at others bluffs and islands or islets, the occurrence of 

 which we have traced at so many points. 



But the evidence of a very considerable elevation is not 

 limited to that furnished by the remains of the elevated reefs 

 just mentioned. It is natural to assume that the elevation we 

 iiave just traced was but a part of a more general elevation 

 which perhaps took place in late Tertiary times, and in wliich 

 the whole group was involved. It is plain that there must 

 have been most extensive denudation and erosion going on 

 throughout the group for a very considerable period of time, 

 geologically speaking. The outlines of the islands deeply 

 furrowed by gorges and valleys, the sharp and serrated ridges 

 separating them, the fantastic outlines of the peaks of Viti 

 Levu, Vanua Levu, and Ovalau, all attest to the great work 

 of atmospheric agencies which has been going on for so long. 

 The separation of islands, islets, or isolated rocks from the 



18* 



