VI YANAWAI COAST 95 



followed during the emergence of this part of the island. The 

 absence or rarity of dykes is remarkable ; but most of the hills 

 would represent volcanic "necks" whether of massive rock, 

 tuff, or agglomerate. 



The District Between the Kumbulau Peninsula and 

 THE Yanawai River. — Between Nandi Inlet and the village of 

 Rewa the sea-border is low and often swampy, whilst occasional 

 spurs descend from the inland range into the swamps without 

 reaching the coast. Pebbles of "soapstone " (foraminiferous mud- 

 rock) occur in streams and are no doubt derived from the incrusting 

 deposits of the neighbouring hill slopes. In one stream-bed in the 

 swamps is exposed in situ a remarkable chocolate-coloured rock 

 that looks like a greasy pitchstone or a palagonite-rock. It is 

 however of detrital origin, and is composed in mass of minute 

 fragments of a basic, sometimes vacuolar, glass in great part 

 converted into palagonite ; whilst there are a number of broken 

 crystals of olivine and plagioclase. Through the palagonitic 

 alteration the fragmental character is somewhat obscured, zeolites 

 being extensively developed in the interstices. A little lime occurs 

 and there is a suspicion of foraminifera. The deposit belongs to 

 the group of palagonite marls described on page 335. The deeper 

 rocks of the district are represented in a spur by an altered augite- 

 andesite, originally hemicrystalline and containing much granular 

 ^pidote. 



Proceeding northward from the village of Rewa, one crosses 

 mother spur descending from the inland range. It is formed in 

 nass of a dark doleritic olivine-basalt (spec. grav. 2 '91) charac- 

 :erised by the length of the felspar-lathes ('28 mm), possessing a 

 Jttle interstitial glass, and referred to genus 25 of the olivine class, 

 t probably represents an ancient flow. Its surface is incrusted, as 

 J ligh as the road ascends, nearly 200 feet above the sea, by fine and 

 ( oarse palagonite-tuffs ; whilst the pebbles of foraminiferous mud- 

 jock in the stream indicate the existence of incrusting marine 

 ( leposits further up the slopes. The road then leads down into a 

 ] Dw-lying undulating district that forms the sea border as far as the 

 1 louth of the Yanawai, and reaches about two miles inland without 

 < xceeding an elevation of 100 feet, although low hills occur here 

 I nd there. This region is fronted by mangrove swamps and is 

 t -aversed by the Matasawalevu and Ndranimako streams. It is a 

 c istrict of basic tuffs and foraminiferous clays, which, as shown 

 I elow, extend up the slopes of the basaltic Wainunu table-land that 

 1 3S behind. The soil in all the low country between Rewa and the 



