192 A NATURALIST IN THE PACIFIC chap, 



west by projecting points, where we find elevated reef-limestone^ 

 40 or 50 feet above the sea, displaying massive corals and large 

 " Tridacna " shells in their natural position, and overlaying a 

 cement-stone composed of blocks of volcanic rocks in a calcareous 

 matrix. On the beach on the west side of the bay there is 

 exposed a reddish-grey altered pyroxene-andesite, which, as 

 regards the size of the felspars of the groundmass and other 

 characters, appears to be an altered form of the prevailing 

 basaltic andesites of the peninsula. In the midst of the low 

 passage that isolates the peninsula, which I have termed the 

 Naindi Gap, there is displayed a highly altered basic andesite 

 which contains a white, zeolitic mineral in its numerous cracks. 



The small island of Na-Wi consists of two low hills, the highest 

 130 feet in height, connected by a mangrove swamp and a sandy 

 beach. There is no trace of a crateral cavity. The prevailing 

 rock is a porphyritic, compact, basic andesite, differing from the 

 other rocks of the neighbourhood in the greater amount of glass 

 it contains. Though it is not easy to find a good, unweathered 

 specimen of the rock, it would appear that Na-Wi represents an 

 old volcanic neck. 



We may infer from the above description of this peninsula that 

 it has a history similar to that of most other parts of the island. 

 There is evidence in the upraised reefs and in the " Globigerina " 

 clays and limestones of considerable submergence at one period ; 

 and it is highly probable that the prevailing basaltic andesites are 

 the products of submarine eruptions. In my account of the hot 

 springs given on page 26, reference is made to the absence of any 

 trace of a crateral cavity in that locality. The same is true, as far 

 as my observation goes, of the whole peninsula. Altered rocks do 

 not occur in the vicinity of the springs, but they are to be found 

 at distances a mile and more away. It does not seem possible to 

 restore in imagination the original form of this part of the island. 

 The present contours are the results of more than one reshaping 

 of the surface through the agencies of marine erosion and sub- 

 aerial denudation. 



The District Between Naindi Bay and the Salt Lake 



Three or four of the peaks of this hilly district rise to about 

 1,000 feet or rather over, the highest being that of Na Suva-suva, 

 which attains a height of 1,110 feet. Since my acquaintance with 

 this region is incomplete, I will confine my remarks to the localities 

 actually examined. 



