136 A NATURALIST IN THE PACIFIC chap. 



Vatuloaloa, Nambuonu, and in another unnamed inland locality, 

 are briefly mentioned on page 31. 



The Sealevu Divide.— This broad range which separates 

 the Ndreketi and Lambasa basins is an offshoot from the central 

 mountains at Sealevu and reaches the coast just east of Nanduri. 

 Its highest part according to the elevation given in the Admiralty 

 chart is 1,437 feet. The road from Sealevu to Nanduri, which 

 crosses its broad level summit for a distance of about three miles, 

 does not rise over 1,100 feet. Between 800 and 1,100 feet are 

 exposed calcareous tuffs and clays all largely made up of pala- 

 gonitic materials. The coarser might be described as sandstones. 

 The clays have 12 per cent, of lime and are foraminiferous and 

 are of the type described on page 321. The rocks displayed on 

 the lower northern slopes on the way to Nanduri are at first the 

 same submarine deposits, and afterwards decomposing basaltic 

 andesites. It is apparent that in the central elevated part of this 

 range there are hills of volcanic formation more or less completely 

 buried beneath these deposits. 



The District between Nanduri Bay and Wailevu 



River 



The sea-border between Nanduri Bay and Middle Point, nearly 

 four miles to the east, consists of a fringe of lowland margined by 

 the mangrove-belts and banked by a line of hills between a quarter 

 and two-thirds of a mile inland. These hills form a continuation 

 of the Nawavi coast range of mountains extending from Ravi- 

 ravi Point to Nanduri. They attain their greatest height in the 

 case of Ulu-i-sori, a cockscomb-like peak 1,141 feet above the sea. 

 Another of these hills, Vatu-tangiri, is capped by a remarkable 

 obelisk-like rock. Behind this coast range lies a hill with an eleva- 

 tion of nearly 1,400 feet. 



The rocks exposed for the first mile or two along the coast 

 east of Nanduri are agglomerates and basic tuffs. The blocks of 

 the agglomerates, however, are made of an altered grey porphyritic 

 rock which has the characters of a porphyrite of a rather acid 

 type.i This composition of the agglomerate is quite exceptional 



1 It is referred to the 5th sub-order (genus 18) of the hypersthene-augite- 

 andesites characterised by prismatic pyroxene and more or less parallel felspar 

 lathes in the groundmass, as described on p. 289. It displays abundant opaque 

 porphyritic plagioclase giving extinctions of oligoclase-andesine. The pyroxene 

 phenocrysts have dark alteration-borders. There is a little altered interstitial 

 glass. Spec. grav. 2-55. 



