6 A NATURALIST IN THE PACIFIC ch. i 



the sea, and beyond rises an irregular group of hills and mountains 

 which attain their greatest height in Nailotha, ^ 2,48 1 feet above the 

 sea. We are now near the limit of the area of basic rocks. Follow- 

 ing the profile as it slopes away, marked by occasional peaks and 

 breaks, towards Undu Point, we pass at first over a district where 

 basic rocks are mixed with those of more acid type ; but before we 

 reach Mount Thuku we enter the district of oligoclase-trachytes, 

 quartz-porphyries, and rhyolitic tuffs, that extends to the extremity 

 of the Undu promontory. 



There remains to be noticed the profile of the Natewa Peninsula. 

 As shown in the diagram, this level begins at a few feet above 

 the sea in the vicinity of the Salt Lake ; and as it proceeds east- 

 ward it attains a level of 1,960 feet in Ngalau-levu and of 1,540 

 feet in the Waikawa promontory, finally culminating, as it nears 

 Kumbulau Point, in a mountainous district which attains its 

 greatest elevation of 2,740 feet above the sea in the lofty ridge of 

 Ngala, the Mount Freeland of the chart. Altered basic rocks 

 prevail in this peninsula ; but more acid andesites also occur, and 

 foraminiferous tuffs and clays are exposed on the slopes, reaching 

 to over 1,000 feet above the sea, 



I will conclude this reference to the profile of the island with 

 the remark that if I had neglected to indicate here the close 

 connection that exists between the nature of the surface-configura- 

 tion and the character of the prevailing rocks I should have 

 ignored a means of investigation which has proved of the greatest 

 value. The rock and surface characters go together. The inland 

 plateau now upheaved 1,000 feet above the sea, was built up by 

 submarine flows of basaltic lava. The isolated conical peak that 

 so unexpectedly intrudes itself into the view is the dacitic core of 

 some submarine volcano long since stripped of most of its frag- 

 mental coverings. The lofty mountain-ridges that run athwart the 

 island's breadth, with their summits usually in the rain-clouds 

 received their coverings of tuffs and agglomerates ages ago when 

 they were submerged ; and now they rise to heights of over 3,000 

 feet above the sea. Bound up with the mysterious origin of these 

 great ridges is the history of the island of Vanua Levu. 



These preliminary remarks are only intended to serve as a 

 general introduction to the detailed description of the island and 

 its formations. The closing chapter is devoted to a summary of 

 the principal results of my investigations. 



^ There has been some confusion in the native names of the peaks in this 

 part of the island, which I have not been able to remove. 



