At times massive and comparatively fresh-looking basaltic rocks are exposed _in situ_ on the mountain sides in the midst of these submarine deposits. A specimen obtained at 1,800 feet is a semi-ophitic porphyritic olivine-basalt with a specific gravity of 2·86 and showing a little interstitial glass. The mode of exposure did not admit of my ascertaining the exact relation of these rocks to the deposits. They are no doubt dyke-like masses representing the original fissures of eruption of a submarine vent; and during the emergence they were covered up with tuffs and deposits, the work of the marine erosion of the emerging land. These, however, are points on which light will be thrown when we come to examine other localities.
Descending the northern slopes of the range from the summit to Sealevu the general course was N.N.E. Several valleys were crossed, of which that occupied by the Na Sinu river was 600 feet in depth, the rivers and streams all flowing to the north-west into the Ndreketi basin. Basic tuffs and agglomerates were exposed at the surface all the way down to Sealevu, 400 feet above the sea.
At the head of the Sealevu valley, about a mile or rather more above the village, and a little east of the track followed in the descent above described, the mountain-range terminates abruptly in lofty cliffs 400 or 500 feet in height. At their base, which is about 1,000 feet above the sea, once stood the village of Lovutu. These cliffs are formed of basic agglomerate-tuffs which display a horizontal arrangement, but there is no distinct bedding. They have the castellated appearance that often characterises horizontally bedded sedimentary formations. The inclosed rock-fragments vary in size from 18 inches to half an inch and smaller. The larger are angular or sub-angular, and are composed of hemicrystalline basaltic andesites, scoriaceous and vesicular and sometimes amygdaloidal. The smaller fragments are more or less rounded and of the same material. The matrix is made up of fine detritus of the large fragments and of lapilli of a vacuolar palagonitic basic glass, whilst small crystals of calcite fill the cavities and line the fissures. The phenocrysts of plagioclase and augite inclosed in the altered glass also display extensive alteration, and in the first case are largely replaced by calcite, secondary quartz, and other products. No organic remains came under my notice; but on account of the alteration of the tuff-matrix their preservation could hardly be expected. Bearing in mind, however, the fossiliferous character of the tuffs and agglomerates in the higher part of the range, it can scarcely be doubted that the agglomerate-tuffs of the Sealevu cliffs are also submarine.