96 A NATURALIST IN THE PACIFIC CHAP. 



Yanawai is red, heavy, wet, and clayey ; and affords a contrast to 

 the dry friable soil of the Kumbulau and Kiombo region to the 

 southward. 



The Navakavura plain lying north of Rewa deserves especial 

 mention. It is a low, swampy district which a mile inland is raised 

 only 20 or 30 feet above the sea, and is mostly occupied by 

 casuarina and pandanus trees. Red argillaceous rocks, repre- 

 senting more or less decomposed palagonite coarse and fine tuffs, 

 are exposed in the banks of the streams. Some of them were 

 originally made up of fragments of basic glass which after being 

 palagonitised became much disintegrated. A typical specimen 

 by my side has a soapy feel and looks like a lump of red 

 clay. Microscopical examination shows that it is composed in 

 mass of palagonite, but in an extreme stage of the alteration 

 process. 



After traversing the Navakavura plain, one crosses a low hill 

 rather over 100 feet above the sea before descending to Ndrani- 

 mako. On the hill are exposed reddish clay-rocks, much weathered, 

 but showing vegetable remains and a few univalve and bivalve 

 shells. Extensive submarine deposits occur in the inland district 

 west of Ndranimako. They are the usual foraminiferous clay- 

 rocks or " soapstones," and in places they contain pteropod shells. 

 They are well displayed in river-banks, and in the hill-slopes on 

 either side ; but they are probably of no great thickness since in 

 one locality named Na Savu, nearly two miles west of Ndrani- 

 mako, the underlying basaltic rock is exposed in the bed of a 

 gully, the sides being of " soapstone." These deposits were formed 

 in comparatively deep water. 1 The greatest elevation at which 

 they were observed was about 100 feet ; but this was as high as I 

 reached in the ascent of the river. According to the natives, who 

 are very observant in such matters, these submarine deposits ex- 

 tend up the slopes of the adjacent Wainunu plateau. On page 86 

 reference is made to their occurrence on the slopes of this basaltic 

 table-land, i or 2 miles farther north. 



In the district between the Ndranimako and the Yanawai rivers 

 basic tuffs and "soapstone" prevail. In this locality, and espe- 

 cially in the vicinity of Ndranimako, siliceous concretions 2 to 

 3 inches across, occur in places on the surface. Their nature is 

 described in Chapter XXV. 



From the foregoing remarks it may be inferred that the sea- 



1 They are described on p. 322. 



