GEOLOGICAL OHSERVATIONS IN FIJI. 



83 



their very base, the lagoon depths are 12 to 10 fathoms. Even if the 

 cliffs were cut by the waves during the Glacial epoch, the waves, work- 

 ing at present sea-level since that period, shoukl have cut a bench of 

 considerable width. Such a bench does not exist. 



The dill's may, therefore, be due to a sub-recent wave-cutting, 

 followed by recent subsidence; or they may be due to faulting. 

 Hence the embayment of the local coast-line was not caused by the 

 return of water to the ocean after the Glacial epoch but to actual 

 subsidence. Such subsidence may be the more readily postulated in 

 view of the general crustal instability in Fiji. 



The presence of nearly a hundred feet of limestone at the eastern 

 side of the island, overlying an irregular surface of volcanic rocks, 

 leads to the inference that Kandavu wxis probably involved in the 



Figure 40. Cross-section of Elevated Limestones near the Village of 

 Kandavu, Kandavu. 



Blocked — elevated limestone. Dashed — silicified ash. Dotted — ande- 

 site. 



general subsidence affecting most of the islands of Fiji. The dis- 

 membered slopes of agglomerate and ash composing the numerous 

 islands at the northern end of the Kandavu lagoon show that profound 

 erosion has taken place within the island group. It may be that an 

 older island once lay at the eastern end of the present lagoon of Kan- 

 davu, separated by a strait from another volcanic mass which now 

 forms the small island of Solo within a separate lagoon. The deep 

 erosion and subsidence of these volcanic islands allowed the present 

 reefs to develop about them. Later extrusion then built up the 

 western part of Kandavu. 



In contrast to this view, it may be held that after the formation of 

 the island in its present outline, a recent subsidence has tilted down 

 its eastern portion and so formed the Great Astrolabe Reef. Lack of 

 sufficient data makes impossible a connected outline of the develop- 

 ment of Kandavu, but, in general, it has had a history not unlike that 

 of the Exploring Group. 



