viii NGANGA-TURUTURU CLIFFS 119 



an elevation of 750 feet a semi-vitreous scoriaceous variety of 

 these rocks, in which the steam-pores had been drawn out into 

 long tubular cavities half an inch and more in length. The scori- 

 aceous character is infrequent ; but reference should here be made 

 to another exposure of a slaggy semi-vitreous rock showing 

 abundant steam-pores in the tuff-district of the river valley above 

 Ravuka. It differs in some respects from the prevailing rock, since 

 it displays prismatic augite as well as felspar microliths in its 

 glassy groundmass, and is for this reason referred to genus 20 of 

 the augite-andesites. In the elevated region east of Savulu the 

 aphanitic augite-andesites are in places overlain by tuffs and 

 agglomerates formed of the same materials. There is a very good 

 exposure of the tuffs in the Nganga-turuturu cliffs about 2 miles 

 west of Savulu. 



(3) The Nganga-turuturu Cliffs. — These picturesque 

 cliffs, 50 to 70 feet in height, rise up at the head of the Liwa-liwa 

 valley between Savulu and Ndrawa. They are elevated about 1,200 

 feet above the sea ; and probably derive their name from a small 

 waterfall which, after descending over their face, drops into the 

 valley below. At its bottom is situated the hamlet of Liwa-liwa, 

 which is about 600 feet above the sea. This is the Fijian word for 

 "cold," and doubtless it has allusion to the coolness of the valley. 

 On account of the more rapid weathering of the tuffs in the lower 

 part of the cliffs, there is a rude shelter afforded by the overhanging 

 portion which is the main feature of interest that the cliffs present 

 from a native's point of view. 



The tuffs composing the cliffs are horizontally bedded and over- 

 lie the prevailing aphanitic augite-andesite exposed on the valley- 

 slopes below. Originally grey in colour, they have been largely 

 affected by the hydration accompanying the weathering process. 

 They are fine in texture and somewhat friable, but contain no lime, 

 and are chiefly made up of the palagonitised fine detritus of 

 vitreous varieties of the aphanitic augite-andesites of the district. 

 No organic remains came under my notice. Some of the beds 

 contain a number of lapilli of basic pumice, 1 to 3 centimetres in 

 size, which are often in the last stage of the disintegration pro- 

 duced during palagonitisation. It would seem probable that these 

 lapilli, after having been ejected from some supra-marine vent, 

 were deposited with the tuffs in the sea around. It should, how- 

 ever, be not forgotten that vesicular and pumiceous materials may 

 be discharged during a submarine eruption. When I visited the 

 museum at Catania, Prof. Platania showed me portions of a bomb, 



