208 A NATURALIST IN THE PACIFIC CHAP, 



THE SOUTHERN SEA-BORDER BETWEEN VUINANDI AND 

 THE VICINITY OF TAWAKI 



The basic rocks, which characterise this long extent of coast, 

 give place about two miles west of Tawaki to the acid rocks. I 

 will proceed methodically with the description from Vuinandi 

 eastward. 



(a) The coast between Vuinandi and Nakarambo. Along this 

 coast, spurs from the Mount Thurston Range reach the borders of 

 Natewa Bay, forming a succession of small bays a mile or so across, 

 on the shores of which are situated the villages and towns of 

 Vuinandi, Ndaku-ndaku, Korotasere, and Nakarambo. The basaltic 

 rocks characteristic of the Vicinity of Vuinandi are predominant here ; 

 but agglomerates and tuffs are of rare occurrence, the prevailing 

 rocks exposed in the spurs being fine textured basaltic andesites 

 (sp. gr. 2*82). A calcareous tuff-clay is, however, to be observed in 

 the east point of Vuinandi Bay, where it is apparently penetrated 

 by a dyke of the above mentioned rock. In Ndaku-ndaku Bay 

 there issue from the shore-flat between the tide-marks some hot 

 springs which are referred to on page 34. 



(b) The coast between Nakarambo and Waimotu. In this tract 

 we meet with rocks of a somewhat different character, though still 

 basic in their type. Through the agglomerates and agglomerate- 

 tuffs of the spurs protrude coarsely crystalline grey pyroxene- 

 andesites. 1 They are to some degree altered, and are characterised 

 by their abundant phenocrysts of plagioclase and of rhombic and 

 monoclinic pyroxene, the groundmass being relatively scanty. 

 The agglomerates are formed of similar materials. There is an 

 interesting exposure in the point east of Nakarambo. My 

 specimens from this locality were unfortunately lost ; but in my 

 notes reference is made to the coarsely crystalline grey andesite 

 above noticed, to the later intrusion of a dark amygdaloidal rock, 

 and to an altered calcareous tuff. 



(c) The coast between Waimotu and Natasa Bay. A low belt 

 of land often forms the sea-border. Between these two localities 

 there is a broad estuary, the village of Vanuavou being situated on 

 the right side and Malati on the left side. Tuffs usually calcareous 



1 These rocks are in most cases referred to the orthophyric ancTfelsitic 

 orders of the hypersthene-augite andesites. The rocks of the last-named^order 

 prevail, and form the type of the group, as described on p. 291. 



