NANDRONANDRANU 117 



The NANDRONANDRANU DISTRICT. 



Lying north-west of Vatu Kaisia is an elevated district which 

 I have named after its highest summit, a square-topped peak rather 

 higher than Vatu Kaisia and probably about 2,100 feet above the sea. 

 Koro-ni-yalewa, which signifies " town of the women," is another 

 name of this peak. It is shown in the sketch given on page 113, 

 and is situated about two miles north-west of Vatu Kaisia. I did 

 not ascend this mountain, which from its form would seem to be 

 made of an acid andesite like the Ndrandramea peaks. Much of 

 this elevated region varies between 1,000 and 1,500 feet in elevation. 

 It is connected with the Ndrandramea district by somewhat broken 

 country not much over 1,000 feet in height, which is the "divide" 

 between the river systems of the Ndreketi and Wainunu. A long 

 tongue-like extension of similar elevation projects to the north- 

 west between the Ndrawa and Navuningumu branches of the 

 Ndreketi. This elevated region is continuous to the eastward with 

 the Tavia Range which is described below. For convenience the 

 valleys of the upper course of the Ndrawa river have been included 

 in this district as their geological features can in this connection be 

 best explained. 



This region is well distinguished from most of the other districts 

 of the island by the prevalence of aphanitic augite-andesites. 

 These rocks have also supplied the agglomerates of the locality, 

 and the palagonite-tuffs which are in places extensively represented 

 are evidently in great part derived from vitreous forms of the same 

 rocks. We seem to get nearer to supra-marine eruptions in this 

 region than in most others. The palagonitic-tuffs and agglo- 

 merates appear to have rapidly accumulated in shallow water, and 

 there is reason for regarding one exposure of the aphanitic augite- 

 andesites as at all events a shallow-water lava-flow. The aphanitic 

 character of the massive rocks, however it may have arisen, is here, 

 as I take it, associated with the shallow-water habit of the tuffs 

 and agglomerates. 



(i) East Side of the Nandronandranu District.— By 

 following the track leading from the ridge on the west side of Vatu 

 Kaisia northward to Ndrawa one rises gradually to a more elevated 

 region. The rocks exposed on the surface for the first mile are for 

 the most part altered hypersthene-augite-andesites possessing a 

 micro-felsitic groundmass. When a height of about 1,400 feet was 

 attained, the track could not have been far from the peak of 



