The crest of the range is here only a narrow ridge. I followed it along in a north-west direction, gradually ascending on the way, and in time the rubbly pitchstone gave place to a hardened palagonitic clay rock, which was observed as high as 2,300 feet. It apparently contains a little lime, and probably was at one time foraminiferous; but it is now much affected by hydration. Soon after this, we arrived at the foot of the steep ascent leading to the summit of Va-lili. We were now rather over 2,400 feet above the sea; but my natives refused to go on, the heavy rain having made the slope too slippery for a safe ascent. With much reluctance I retraced my steps; and as the bad weather continued for several days after, I did not make another attempt. There would, however, be no difficulty in dry weather.
(2) Traverse of the Va-lili Range from the old site of Loma-loma to Waiwai on the coast of Savu-savu Bay.—This route, which was taken by Mr. Horne, the botanist, in the reverse direction in 1878, is thus described in his book, A Year in Fiji (p. 19): “The path, rough and apparently not much used, ran along streams, up steep ascents and down awkward descents, over slippery boulders and fallen trees, up the sides and along the crests of densely wooded mountains.”
Ascending the north slope of the range I found at the Tangi-nandreli cave, which is 1,050 feet above the sea, a palagonite-tuff-sandstone underlying the basic agglomerate. This tuff, which is of the type described just below, does not effervesce with an acid, and shows no tests of foraminifera when examined with a lens. Further up the slopes large masses of agglomerate occur. At 1,350 feet I came upon a large mass of a fine-grained compacted palagonite-tuff made up chiefly of fragments of palagonitized vacuolar basic glass. Among the mineral fragments occur plagioclase, augite, and rhombic pyroxene, and a little fresh olivine, which is of very rare occurrence in these palagonite-tuffs. It contains little or no lime, and shows no tests of foraminifera in the slide. The summit of the range is here about half a mile broad, and is relatively level. I placed its elevation at 1,760 feet, which is not far from Horne’s estimate of 1,800 feet. The southern slope, which is the rainy side of the range, is much cut up into gorges. In the upper 200 feet palagonite-tuffs, similar to those above referred to, are displayed, and basic agglomerates occur lower down.... This part of the range is remarkable through being completely covered over by palagonite-tuffs and agglomerates. It has been pointed out above that this is not the case with the range close to the highest peak, where the underlying rocks are in part exposed at the crest of the range.
(3) The Eastern Peak of the Va-lili Range.—This hill, about 1,100 feet in height, overlooks the Mbale-mbale branch of the Ndreke-ni-wai river. At its foot near the river there is exposed at the roadside a rubbly pitchstone formed of a basic glass, inclosing porphyritic crystals of plagioclase, augite, and olivine, which is described on page [313]. Here also occurs an agglomerate made up of blocks of a semi-vitreous basaltic andesite (sp. gr. 2·78), showing prismatic pyroxene in the groundmass, and referred to genus 20 of the augite-andesites.
The upper part of the hill displays the same agglomerate, and a tuff-agglomerate in which small fragments of the basaltic andesite are inclosed in a matrix largely made up of fine debris of basic glass. There protrudes through these detrital rocks at the top of the hill a broad dyke-like mass of the same basaltic andesite that forms the agglomerate around; and the structure of the hill is thus displayed as that of an old volcanic neck. It has evidently an axis of massive basaltic rocks, more or less covered over with agglomerates and tuffs.
(4) The Nambuni Spur.—This singular spur runs down to the coast between Waiwai and Wailevu; but it is partly separated by a deep gap from the main range. It attains a height of 550 to 600 feet, and has two little peaks which the natives call Vatu-tolutolu and Vatu-tangitangiri. Its position is shown in one of the profile-sketches of Va-lili, given on page [141]. The crest of the spur is formed by a dyke-like mass, 25 to 30 feet thick, which is composed of a basic agglomerate passing down into a palagonite-tuff. The blocks of the agglomerate are composed of a semi-vitreous basaltic andesite, showing minute felspar-lathes in flow-arrangement in an abundant smoky glass, the fine pyroxene being not differentiated. The tuff, into which the agglomerate passes down is non-calcareous, and displays no organic remains. It is, however, composed of fragments, which do not generally exceed a millimetre in size, of palagonitised vacuolar glass, basic andesites, plagioclase, monoclinic and rhombic pyroxene, &c.
This dyke-like mass forms the axis of the ridge and protrudes vertically about 100 feet, the bulk of the spur being composed of a compacted brecciated palagonite-tuff made up mainly of fragments a centimetre in size, of a basic vacuolar glass, sometimes fibrillar, which is extensively palagonitised.
The filling up of a fissure in a mass of tuff-breccia by palagonite-tuffs and agglomerates probably occurred during the submergence, the original dyke-rock having been removed by marine erosion. After the emergence the subaerial denuding agencies reshaped the surface, and as a result of the less yielding character of the materials filling the fissure, they protrude as a dyke-like mass from the crest.
In a cliff-face of the adjacent main range there are displayed an agglomerate of basaltic andesite and a pitchstone-breccia, composed of fragments of but little altered basic glass, the interstices being filled up with palagonite. In the case of the Kiombo flow I have endeavoured to explain the origin of a closely similar pitch-stone-breccia (page [92]).
(5) The Sea-border and the Low-lying Districts at the Base of the Va-lili Range.—It may be generally remarked that palagonite-tuffs and clays, often foraminiferous, prevail in these localities. Thus in the sea-border between Waiwai and the mouth of the Ndreke-ni-wai basic agglomerates are displayed where the mountains approach the coast; but further west a broad tract of undulating land, elevated usually 100 to 300 feet, intervenes between the range and the sea-border, and here coarse and fine palagonite-tuffs predominate.... On the north-west the foraminiferous tuffs and clays of the Ndreketi plains approach the Va-lili range in the vicinity of Vuinasanga, and extend for at least 200 or 300 feet up its sides.... At the east end of the range, where the slopes descend to the plains of the Waisali valley, a little west of Mbale-mbale, there are exposed bedded palagonite-tuffs, tilted up at an angle of about 20° to the south-west. They contain a little lime and display microscopic tests of foraminifera, the palagonite being minutely vacuolar, the cavities also being filled with the altered glass. I noticed those submarine deposits at an elevation of 100 feet, but probably they reach much higher.