108 A NATURALIST IN THE PACIFIC chap. 



I noticed a patch of agglomerate, the subangular blocks six to eight 

 inches across being formed of the same acid andesite. In the same 

 way by taking the road from Tembe-ni-ndio to Nambuna, passing 

 the hill of Kala-kala on the way, we leave behind the foraminifer- 

 ous tuffs and limestones of the lower coast regions ; and when about 

 400 feet above the sea we enter the inland district of felsitic 

 andesites which begin about two miles from Tembe-ni-ndio. 



The Navuningumu Range. — By following the track from 

 Nambuna to Navuningumu one skirts the bases of Wawa Levu and 

 Ngaingai, where dacitic rocks are exposed. After passing the water- 

 shed 1 between the Wainunu and Ndreketi rivers, the track descends 

 into the deep valley of one of the western tributaries of the 

 Ndreketi, where a characteristic holocrystalline type of these felsitic 

 andesites is exposed. Approaching Navuningumu one finds 

 exposed at its base agglomerates, composed of scoriaceous and 

 amygdaloidal semi-vitreous basic rocks, overlying a dark tufaceous 

 sandstone which on examination proves to be a basic pumiceous 

 tuff of the type described on page 333, and scantily foraminiferous. 



We stand now in a region of basic rocks on the south-east side 

 of the range, and before us rises abruptly the weird-looking 

 magnetic peak of Navuningumu, which is well represented in the 

 accompanying illustration. In the wet season its summit is usually 

 enveloped in the thunder-clouds. Its elevation above the sea is 

 1,930 feet, but estimated from its base its height is 1,000 to 1,100 

 feet. The natives also name this peak Na Seyanga, after a town 

 that once existed in this locality. It is the summit of a range that 

 extends a mile or more to the north where it terminates in a lesser 

 peak known as Mumu. 



Ascending the peak of Navuningumu from the south-east one 

 finds exposed in its lower part, up to 1,200 feet above the sea, 

 pitchstone-agglomerates (composed of fragments of a vitreous 

 basic rock) and white tufaceous sandstones (containing a few tests 

 of foraminifera), such as are described below in the case of the 

 neighbouring Mbenutha Cliffs. Between 1,300 and 1,500 feet there 

 is displayed in position a typical dacite of the type described on 

 page 303. 



The peak itself is formed of a dark-brown slightly vesicular 

 semi-vitreous basaltic andesite, of which, in fact, for the upper 200 

 feet, the summit is composed. The rock is somewhat rubbly ; and 

 where it is exposed on the bare peak it is powerfully magnetic, 



1 The track attains an elevation of about 1,300 feet, but the top of the 

 watershed is two or three hundred feet lower. 



