114 A NATURALIST IN THE PACIFIC -chap. 



from the west side. The regions traversed on the way are so 

 densely wooded that the mountain does not become visible until 

 the traveller is right upon it. He becomes suddenly aware that 

 there is some huge mass close to him looming above his head 

 through the trees ; and it is with a feeling of awe that he first 

 looks upon a mountain that although only a few hundred yards 

 away nearly escaped his search. He is startled by its proximity, 

 and wonders what strange forces have been at work to place it 

 there ; but his view is transitory, and whether proceeding north or 

 south he sees it no more, unless he essays to climb its slopes. 



Vatu Kaisia lies not in the centre but towards the west side of 

 the Yanawai valley the river flowing as an impetuous stream 

 around the foot of ts eastern slope. In the profile-sketch the 

 mountain itself conceals the peculiar feature of its position, which 

 is, however, shown in an exaggerated form in the geological section 

 below. On its west side rises a broad ridge running south which 

 in places is not much higher than the basaltic plateau of Wainunu 

 to the west of it. This ridge is only separated from Vatu Kaisia 

 by a dark narrow gorge not many hundred yards in width, across 

 which my natives were able to make themselves heard when near 

 the summit. The mountain rises i,ioo or 1,200 feet above the 

 gorge on its west side, which is 700 feet above the sea, and some 

 1,400 or 1,500 feet above the Yanawai river on the east, which is 

 300 or 400 feet above the sea. It possesses two peaks, of which 

 the western one is smaller and lateral and has a height of 1,600 or 

 1,650 feet, whilst the eastern is the main peak and rises to 1,880 

 feet. The saddle between the peaks has an elevation of about 

 1,500 feet. It is very difficult to obtain a distant view of the two 

 peaks, which lie about N.W. and S.E. with each other. They are 

 either merged into one as in the view from the south, or else the 

 highest portion of the main peak is alone visible. 



On the lower slopes of the mountain as high as 1,100 or 1,200 

 feet is exposed a porphyritic doleritic basalt showing semi-ophitic 

 augite and abundant interstitial glass. Its specific gravity is 2'8, 

 but there is no olivine. It belongs to a type of basalt described 

 under genus 9, sub-genus A, of the augite-andesites. The upper 

 double-peaked portion rises precipitously, displaying bare rocky 

 cliff-faces with a drop of 100 or 150 feet, and formed in mass of a 

 grey andesitic rock with a specific gravity of 271 and showing 

 abundant small porphyritic crystals of hornblende and rhombic 

 pyroxene. It represents a type of the hornblende-hypersthene- 

 andesites described on page 301. I was unable, through want of 



