GEOLOGICAL OBSERVATIONS IN FIJI. 89 



The later history of the island has been characterized by uplift dur- 

 ing Pleistocene and Recent times. Indeed, the Fiji group as a whole 

 cannot be included in Darwin's or Dana's typical areas of progressive 

 subsidence. The upward movement in southeastern Vanua Levu has 

 continued into so recent times that near Vunelangi a lagoon flat and 

 outer reef are preserved in all their details though elevated 50 to 75 

 feet above the present sea-level. 



No remnants of corallifcrous limestone occur near the summit or 

 along the upper flanks of the ridges of Vanua Levu. This may best 

 be explained by the very rapid erosion of the underlying weak deposits 

 of volcanic dust, ash, and submarine tuff. The delta flats formed from 

 this debris which should surround the island are lacking for the most 

 part, though near Vunelangi remnants of a bench of such volcanic 

 waste are found. It is apparent that after uplift the fine clays are 

 soon shifted to the new level. Yet even then they should form delta 

 flats near the present sea-level as they do near Vunelangi. That 

 similar extensive flats do not exist is proof that the recent uplift in 

 southeastern Vanua Levu is replaced throughout the other and greater 

 part of the island by contemporaneous subsidence. 



Previous conditions in Vanua Levu have been obscured by erosion 

 and subsidence. Where uplifted reefs occur they have been elevated 

 only one or two hundred feet. They rest on old land surfaces, indi- 

 cating subsidence. The recent positive shift of the ocean level can- 

 not be identified with the rise of the waters at the close of the Glacial 

 period. It is much too recent. 



From the earlier discussion of Viti Levu and from what has been 

 said of Vanua Levu it is apparent that the larger islands of Fiji have 

 had a very complicated history, and that it is futile to attempt to find 

 any one theory which explains the present position of their reefs. 



Conditions in the Lau islands are not so involved. Their elevated 

 limestones are spoken of by Alexander Agassiz (1898) as Tertiary 

 but the writer considers them Pleistocene or Recent. Two distinct 

 problems are presented. The older elevated limestones represent one 

 cycle of events; the modern reefs represent another. 



With regard to the first cycle, Agassiz (1899) has stated, "Granting 

 even, as is very probable, that when these Tertiary limestones were 

 formed they were formed in great part by subsidence, and in part by 

 accretion from the carcasses of the invertebrates living upon their 

 surface, this would in no way help us to a satisfactory explanation of 

 the formation of atolls and of barrier reefs by the growth of the corals 

 of the present epoch." "The only evidence we have of the great 



