AGASSIZ: FIJI ISLANDS AXD CORAL EEEFS, 71 



for instance, as is done by Dana and Darwin, ns the single cause for 

 the formation of the many different kinds of atolls and of barrier reef 

 islands to be found in the Fijis. 



THE TERTIARY ELEVATED LIMESTONES OF FIJI. 



The existence throughout Fiji of numerous platforms of submarine 

 erosion at average depths varying within very moderate limits seems to 

 indicate a condition of approximate equilibrium as far as either elevation 

 or subsidence is concerned. The elevation of the limestones of late 

 tertiary age clearly indicates that the origin of the greater number of 

 the Fiji Islands dates back approximately to that period. This is un- 

 doubtedly the case with the range of islands known as the Lau or Eastern 

 Archipelago of Fiji. AVith them we should include the more northerly 

 islands, the group to the east of Xgamia, and of Budd Reef, including 

 Thikombia. 



It is more difficult to determine the age of the larger islands, Viti Levu 

 and Yanua Leva, as well as Taviuni, Kandavu, and the volcanic islands 

 of the Ivoro Sea. "We may assume with a certain degree of probability 

 that the age of such islands as Nairai and Xgau corresponds with the 

 age of the volcanic rocks which have lifted the islands of the Lau group 

 to their present altitude. But in Viti Levu and Yanua Levu the 

 problem is more complicated. While elevated coralliferous limestones 

 of late tertiary age occur along the shores of Viti Levu evidently of the 

 same age as the limestones of Lau.-'^yet there is evidence of the existence 

 of older rocks as a nucleus of the larger Fiji Islands. So that until the 

 geology of Viti Levu and of Vanua Levu has been more accurately 

 studied, we must leave their age undetermined ; but enough is known 

 of the geology of the shoi-e line to show that the existence of the great 

 barrier and frino-ing; reefs along the shores of Viti Levu and of Vanua 

 Levu gives no evidence that the great barrier reefs of these islands owe 

 their origin to the gradual subsidence, during our epoch, of the islands 

 themselves. 



The existence of the tertiary elevated coralliferous limestone at so 

 many points in the Fiji Archipelago (Plate 2) seems to indicate a huge 

 limestone bed of great thickness and extent, formed during tertiary times, 

 along the flanks of ancient volcanic islands, and elevated by subsequent 

 intermittent volcanic action during moi'e recent times over ai*eas of 



1 Home {A Year in Fiji, London, 1881, p. 165) says that in Viti Levu and Vanua 

 Levu sedimentary or limestone rocks are found on all mountains. 



