BY W. G. AVOOLNOUGH. 473 



The most remarkable feature of the climb, v/hich was very steep, 

 was the complete absence of solid rock. Everything was rich 

 soil, arising probably from the decomposition of the tuff, of which 

 the mountain is largely built. Not a single outcrop, nor even a 

 loose piece of rock, was met with all the way to within 200 feet 

 of the saddle, where the base of a great precipice of agglomerate 

 is seen some distance away. Another point worthy of note is the 

 extraordinary "razor-backed" character of the ridges. Some of 

 the leading spurs have absolutely no flattening at the top, but 

 slope down at steep angles to great depths on either side. The 

 main backbone of the mountain is not more than a couple of 

 chains wide. This razor-backed character of the ridges is very 

 marked all over the central part of the island, and testifies to 

 the great rapidity of subaerial denudation occasioned by the 

 torrents of rain. 



The southern summit arises from the backbone of the mountain 

 as a column, roughly elliptical in shape, some 150 to 200 feet in 

 average diameter, and bounded by perpendicular cliffs at least 50 

 feet in height. The actual summit is quite another 50 feet higher. 

 The height above sea-level of the base of the column is 3025 feet 

 (aneroid). The rock of which this column is composed is a very 

 coarse agglomerate. The groundmass is made up of comminuted 

 fragments of the rock supplying the large fragments which are 

 up to 6 feet in length. The rock is a beautiful hornblende 

 andesite with tinely developed prisms of hornblende. The cliffs 

 bounding the ridge are apparently composed of similar rock. 

 Time and weather did not permit of the examination of the other 

 peaks, but their structure is certainly identical with that of the 

 one examined, and there is no doubt that the whole mountain is 

 a huge volcano, or rather a line of closely packed sister cones. 

 The summits represent the consolidated fragmental materials 

 w4iich filled the funnels when activity ceased. 



Following up the Wainibua from the village of Wainiveidro 

 no distinct exposures of granite are met with, but the soil has all 

 the appearance of granite soil. At a point about 2h miles above 

 the village a solid outcrop of the rock in situ is met with; it 



