I know little of the coast between Nanduri Bay and the mouth of the Ndreketi River. At two localities where I landed no elevated reef-formation was observed. Dana referring to the coast opposite Mathuata Island alludes only to the volcanic agglomerates. The low mangrove-bordered coast between the mouths of the Ndreketi and Lekutu rivers was not actually visited by me; but I traversed the region behind the broad mangrove-belt, and found occasionally in the tuffs and muds exposed in the river-banks marine-shells and foraminiferous tests, indicating an elevation of a few feet. I examined much of the coast between Lekutu and the extremity of the Naivaka peninsula, but came upon no upraised reef-rocks. In the low isthmus, 20 to 30 feet high, which connects this peninsula with the main island only volcanic rocks came under my notice. A palagonitic tufaceous sandstone exposed in the cliffs on the north coast of Naivaka contains a little carbonate of lime, and being probably a submarine deposit it implies an emergence of the sea-border.
Although I have been able to produce but scanty evidence of uplifted reefs on the north coast of Vanua Levu, it is probable, judging from the heights given in the Admiralty Sailing Directions, that such formations exist in a few of the numerous low islands and islets that front this coast. Some of these islands and islets, which are often not much more than reef-patches largely reclaimed by the mangroves, will be noticed below when considering the question of the extension of the mangrove belts since the survey of Commodore Wilkes in 1840.
Neither on the south coast of the peninsula of Naivaka nor on the west coast of the Sesaleka promontory did upraised reefs come under my observation; but my acquaintance with the last locality is very scanty. The emergence of the Sesaleka promontory is however indicated by the occurrence inland at heights of at least 700 feet of palagonitic tuffs, occasionally containing foraminifera.
With the long tract of coast between Naithombothombo Point and Solevu Bay, I am fairly well acquainted. However, with the doubtful exception of Lekumbi Point, no elevated reef-formations were observed. Evidence of an emergence of a few feet, and of a very extensive seaward advance of the land-surface in recent times, is afforded by a curious bed of marine shells exposed in the banks of the Mbua River, nearly two miles inland and in the vicinity of the Wesleyan Mission station. This is described on page 58. The submergence at some period of the watershed between the Mbua and Lekutu districts is indicated by the presence of microscopic foraminifera in the hyalomelan tuffs that are exposed in the dividing ridge.