GEOLOGICAL OBSERVATIONS IN FIJI. 139 



The andesitic period is considered to be contemporaneous with the 

 second antlositic period of ^'iti Levu and Vaiuui Lewi. In Lakeniba, 

 the augite andesites appear to merge into basalts. The occurrence 

 of both basalt and augite andesites in the larger islands has already 

 been noted. It is possible that these types were erupted at approxi- 

 mately the same tJme and represent phases of a common magma. 



The third, or basaltic period, is characterizetl only by olivine basalts 

 in the Lau Group. The analysis of a basalt from Yanu Yanu (p. 124) 

 is typical of the lavas of the third period. 



The ^•olcanic succession is therefore, as follows : — 



First epoch — rhyolites? 



Second epoch — andesites or basalts. 



Third epoch — basalts. 



Volcanic Succession in the Kandavu Group. 



No unconformities are known between the volcanic rocks of Kan- 

 davu and, hence, no exact dates can be assigned to the various rock 

 types. Judging from the erosion of the islands, three periods may be 

 recognized. Near Vunisea, hornblende andesites are eroded to late 

 maturity; farther northeast, augite andesites and olivine andesites 

 are eroded to early maturity. The very recent peak of Mount 

 Washington, is said to consist of hornblende andesites (Eakle, 1S99, 

 p. 586). Again, hornblende andesites are described from Ono, which 

 has a submature topography, whereas the northern island of Ndra- 

 vuni, with a very similar topography, is composed of olivine basalts. 



Thus, while hornblende andesites have prevailed in all periods of 

 eruptivity, it is thought that the order, hornblende andesite, augite 

 andesite or basalt, hornblende andesite, approaches nearest the truth. 



General Summary of the Volcanic Successions in Fiji. 



Reviewing the succession of lavas which have been recorded from 

 the various islands, the first andesitic period is recognized only in the 

 two large islands of Viti Levu and Vanua Levu. Rhyolitic rocks are 

 associated with this period. The second andesitic period is recog- 

 nized in all the islands in which volcanic rocks are exposed. A diver- 

 sity of lavas were extruded in this period. From Viti Levu, olivine 

 basalts, hornblende and augite andesites are reported; from Ovalau, 

 hornblende andesites; from Vanua Levu, augite andesite, augite- 



