xiv MOUNT FREELAND 205 



and is probably an intrusive mass. A description of it will be 

 found under genus 10 of the augite-andesites (page 274). 



The general petrological characters of the principal summit of 

 Mount Ngala point to its high antiquity as a volcanic mountain. 

 It probably ranks among the oldest extinct volcanic vents in the 

 island. 



Proceeding along the coast from Ngara-vutu to Navetau, the 

 Buli's town of the Tunuloa district, one observes blocks of basic 

 rocks. Farther to the eastward for a distance of two or three miles 

 basic agglomerates and basic tuff-agglomerates prevail along the 

 sea-border, being often extensively exposed in the cliff- faces of the 

 hills. The rock composing the blocks is a hemi-crystalline pyroxene- 

 andesite remarkable for the prismatic pyroxene in the ground- 

 mass, and referred to genus ly of the hypersthene-augite sub-class. 



I crossed the range to Ndevo on the other side of the peninsula 

 from a place three or four miles west of Kumbulau Point, rising on 

 the way to a height of 930 feet. For the lower 300 feet on the 

 north slope basic agglomerates and basic tuff- agglomerates are 

 exposed. They are made up of the same materials as those above 

 described on the coast. Near and at the summit occur compacted 

 brecciated tuffs made up of palagonitised basic materials but con- 

 taining no lime, and these are associated with light greenish 

 fine-textured hard tuffs of an acid character, but without lime or 

 organic remains. In this last case the deposit is formed of mineral 

 fragments (oligoclase, rhombic and monoclinic pyroxene, &c), the 

 debris of a hemi-crystalline volcanic rock, and a quantity of greenish 

 alteration products. 



On the south side in the vicinity of Ndevo the sea-border is 

 composed of calcareous palagonitic clays and tuffs containing 

 pteropod shells and large tests of foraminifera in abundance. 

 These deposits, which are horizontally bedded, extend a mile inland 

 and reach to between 250 and 300 feet up the slopes. A hot spring 

 is stated to occur between the tide-marks near Ndevo. 



At intervals all along the coast between Ndevo and Nuku- 

 ndamu, passing on the way the villages of Koro-i-vonu,Tuvumila and 

 Kanakana, fine and coarse basic tuffs, often calcareous, are to be seen 

 exposed in the sea-cliffs and in the low hills behind. They are 

 bedded and dip 5 to io° W.S.W. near Ndevo and 15 to 20 S. b W. 

 south of Kanakana. The lower slopes of the Ngala mountains here 

 approach the coast, and it is highly probable that the submarine 

 tuffs which form the sea-border extend a considerable distance 

 inland and to some height above the sea. Between Nuku-ndamu 



