_Savage Island_ (S.E. of the Friendly group), is about forty feet in height. Forster[11] describes the plants as _already_ growing out of the dead, but still upright and spreading trees of coral; and the younger Forster[12] believes that an ancient lagoon is now represented by a central plain; here we cannot doubt that the elevatory forces have recently acted. The same conclusion may be extended, though with somewhat less certainty, to the islands of the _Friendly Group_, which have been well described in the second and third voyages of Cook. The surface of Tongatabou is low and level, but with some parts a hundred feet high; the whole consists of coral-rock, “which yet shows the cavities and irregularities worn into it by the action of the tides.”[13] On Eoua the same appearances were noticed at an elevation of between two hundred and three hundred feet. Vavao, also, at the opposite or northern end of the group, consists, according to the Rev. J. Williams, of coral-rock. Tongatabou, with its northern extensive reefs, resembles either an upraised atoll with one half originally imperfect, or one unequally elevated; and Anamouka, an atoll equally elevated. This latter island contains[14] in its centre a salt-water lake, about a mile-and-a-half in diameter, without any communication with the sea, and around it the land rises gradually like a bank; the highest part is only between twenty and thirty feet; but on this part, as well as on the rest of the land (which, as Cook observes, rises above the height of true lagoon-islands), coral-rock, like that on the beach, was found. In the _Navigator Archipelago_, Mr. Couthouy[15] found on Manua many and very large fragments of coral at the height of eighty feet, “on a steep hill-side, rising half a mile inland from a low sandy plain abounding in marine remains.” The fragments were embedded in a mixture of decomposed lava and sand. It is not stated whether they were accompanied by shells, or whether the corals resembled recent species; as these remains were embedded they possibly may belong to a remote epoch; but I presume this was not the opinion of Mr. Couthouy. Earthquakes are very frequent in this archipelago. [11] “Observations made during Voyage round the World,” page 147. [12] “Voyage,” volume ii., page 163. [13] Cook’s “Third Voyage” (4to edition), volume i., page 314. [14] Ibid., volume i., page 235. [15] “Remarks on Coral-Formations,” page 50.