GEOLOGICAL OUSEKVATIONS L\ FIJI. J.) 



The question remains as to why tliere is a t'ringiiij:; reef near the 

 mouth of the Singatoka, while oil' Suva there is a wide and deep hi^n)on 

 within a barrier reef. The wa'iter beUeves that two special causes 

 have produced this effect. First, the sediments brought down in 

 abundance by the Rewa river are very fine. They float for a con- 

 siderable distance out to sea before they are precipitated and are 

 swept by prevailing currents to the westward, along the south shore 

 of the island. The charts show that the reef is indeed fringing east 

 of the river's mouth. The coral is able to grow only beyond the zone 

 of maximum precipitation of the silt. The present barrier reef, 

 therefore, is growing upward on the delta platform of the Rewa 

 river just as the former, uplifted reefs developed in a previous cycle. 



Second, the uplifted marls about Suva Harbor present an irregular 

 coast line and an inland topography which cannot be explained by 

 stream erosion. The direct evidence of block-faulting exposed in 

 the Walu Bay quarry is suggestive that the uplift of the coastal 

 marls was accompanied by downthrow and that the lagoon flat of 

 Suva Harbor represents a depressed portion of the uplifted delta. 



Comparison of Results with those of Previous Workers. 



The history of Viti Levu, as presented above, is somewhat at vari- 

 ance wdth the older accounts of other geologists. Thus, Andrews 

 describes an unconformity between an older and newer series of lime- 

 stones at the mouth of the Singatoka river. The coastal plain series 

 at this point appeared to be entirely conformable but, if the writer is 

 correct and intermittent uplifts have characterized the elevatory 

 movements of the coastal plain series, it would not be surprising to 

 find a slight unconformity between an older series of tilted limestones 

 and the very recently uplifted series of coralliferous limestones occurring 

 west of the mouth of the Singatoka river. 



A more serious discrepancy is found between the mapping of 

 Woolnough and the descriptions of the present writer. Woolnough 

 does not discriminate betw^een the different marls of Fiji. He men- 

 tions the fact that near the mouth of the Rew^a these beds are com- 

 paratively flat, W'hile near the head-waters of the Navua and Rewa 

 rivers they are considerably folded. This variance in structure, how- 

 ever, is not interpreted to mean a difference in age. 



Further, it would appear from his text that Woolnough did not 

 visit the Navua delta plain. He saw the flat country from the hills 



