104 A NATURALIST IN THE PACIFIC chap. 



It is not easy to obtain a view of the profile of this hill and to 

 ascertain its relation to its surroundings ; and it was only when I 

 viewed it from near the top of Vatu Kaisia six miles to the eastward 

 that I was able to understand its position. Looking from that 

 standpoint across the basaltic table-land of Wainunu one observed 

 Soloa Levu rising as a dome-shaped hill at the western margin of 

 the table-land and apparently not separated from it. The examin- 

 ation of the district shows that on the east and south-east sides this 

 hill was in part surrounded by the great basaltic flows by which the 

 table-land was built up. Basic tuffs and agglomerates,lhowever, occur 

 on the lower slopes on the north-west, west, and south-west sides, 

 so that Soloa Levu in fact lies in the midst of an area of basic rocks. 

 The type of acid andesite which is displayed in the upper two- 

 thirds of the hill is distinguished from those of the other hills of 

 the Ndrandramea district by its orthophyric groundmass. Instead 

 of a fine mosaic, the matrix displays as a rule an arrangement of 

 short stout plagioclase prisms ; but in one of my slides the two 

 forms of groundmass are associated. In their general characters 

 as described on page 296, they cannot be separated from the acid 

 andesites of the Ndrandramea district. Their specific weight 

 ranges between 2*54 and 2'62, and like most of the other acid 

 andesites they contain little, if any, interstitial glass. Huge'blocks 

 of these rocks lie about on the slopes, often assuming a columnar 

 form, the fragments of such columns being sometimes 5 or 6 feet 

 in diameter, and 12 to 15 feet in length. I found one such block 

 standing erect like a solitary obelisk. 



The best way to observe the basic rocks that invest the lower 

 slopes of Soloa Levu is to follow the track that skirts it on the 

 south side on the way from Tambu-lotu to Vunivuvundi. Palagon- 

 itic tuffs containing in places a little lime ^ and composed of frag- 

 ments of basic glass of varying size and more or less palagonitised 

 extend from Tambu-lotu and Nuku-ni-tambua (two villages lying 

 about a mile to the westward) to the west and south-west slopes 

 of Soloa Levu. A pitchstone-agglomerate, formed of fragments of 

 a basic glass inclosing large crystals of plagioclase felspar one- 

 third of an inch in length, is associated with these tuffs on the 

 lower north-west, west, and south-west slopes of the hill. The tuffs 

 are formed of the same materials as the pitchstone-agglomerates, 

 but differ in their character of being more or less palagonitised. 

 However, on the north-west side the latter have also undergone 



^ These tuffs are probably submarine. They will be found described with 

 tuffs of the same character on p. 333. 



