80 



FOYE. 



If an island existed here during the submergence of the andesitic 

 hills of the Exploring group, it is reasonable to suppose that this 

 island participated in that submergence. From the great amount of 

 limestone which has been eroded from Vanua Mbalavu since the 

 uplift of this formation, it is probable that the older volcano of Kana- 

 thea lost all its limestone veneer before the building oi the more recent 

 portion of the island. 



The coastal outline of the newer portion of Kanathea, like that of 

 Munia, is comparatively regular and shows little evidence of recent 

 submergence. In fact, as at Munia, recent uplift is suggested by the 

 incision of youthful valleys in the floors of the mature valleys of east- 

 ern Kanathea. 



The history of the island of Kanathea is thus seen to be not unlike 

 that of the Exploring group. 



Mben'gha. 



The island of Mbengha is far removed from Kanathea, but many 

 of its features are so similar that they wull be discussed in the light 

 of facts gathered at Kanathea. The reef about Mbengha is elliptical 

 in shape, its longest axis extending northeast by southwest. The 

 lagoon is 16 miles long and 10 miles wide. In its northwestern part 

 lies Mbengha, a circular island four miles in diameter. The island 



BEACON WAI SOMO 



/(GGlOM£RAT£ RIDCt 



Figure 39. View of Mbengha as seen from the Northeast. 



is composed of agglomerates and flows of augite and hornblende 

 andesite, carved into sub-mature topography. 



The northwestern slopes are long and even, following the original 

 dip of the andesitic flows. The preservation of these slopes is proba- 

 bly due to the small rainfall on this side of the island. 



The accompanying sketch of Mbengha (Figure 39), made from the 

 northeast, shows the sharp peaks of its central portion and the deep 

 bay of ]\Ialumu indenting its northeastern side. The bay represents 



