442 A CONTRIBUTION TO THE GEOLOGY OF VITI LEVU, FIJI, 



fails, and pseudomorphs of magnetite and augite after hornblende 

 appear. Massive products of eruption are quite subordinate to 

 f ragmen tal ones, but numerous dykes and sheets or sills occur. 

 One of the former, Devo,* has given rise to an imposing piece 

 of scenery. In all instances these rocks are perfectly fresh, and 

 have not suffered at all from orogenic processes. 



The contrast in form and structure between this range and the 

 Rewa Plateau, immediately to the eastward, is very striking. 

 Soft soapstones run right up to the base of the range, but, at a 

 very short distance within the gorge of the Wainivalau, the 

 agglomerates rest upon granites and jointed rocks. The actual 

 junction-line is obscured. The importance of this structure is 

 discussed later (p. 448). 



The forms of the peaks of the range are wevy suggestive of a 

 line of volcanic necks'partially denuded.f Nacau, at the northern 

 end of the range, has very strikingly the appearance of a crater 

 rising 1230 feet from the level of the plain to the eastward. Its 

 shape is crateriform, the highest point of the rim lying to the 

 west. The northern portion of the rim, for about a quarter of 

 its circumference, is broken down; and the central portion is 

 occupied by a deep crateral hollow. The southern face exhibits 

 a steep cliff formed by a subsidence of the outer crater-slopes on 

 that side. The northern end of Nariko, facing it across the valley 

 of the Wailase, exhibits a similar cliff; and the ridge joining the 

 two and rising to a level of about 600 feet above the plain probably 

 represents a sunken block. 



The cliffs and eastern side of the ridge consist of andesite 

 agglomerate, but the western side of the ridge is of diorite 

 porphyry. The latter rock extends for some distance westward 

 along the valley of the Waiqa River. It will be discussed in the 

 description of that area. 



■" Former paper, p. 467, plate xxiii., fig. 4. 

 t The high range of hills in the background in the view of Nabukelevu 

 (former paper, plate xxiv., fig. 5) has no existence either in fact or upon my 

 negative; it is a creation of the process engraver. The hills behind Nabu- 

 kelevu were hidden in mist when the photograph was taken. 



