Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.3)

April, 1836. areas of alternate movements, 563 pass over the space of ocean immediately adjoining it, and proceed to the chain of islands including the New Hebrides, Solomon, and NeAv Ireland, Any one who examines the charts of the separate islands in the Pacific, engraved on a large scale, will be struck with the absence of all distant or encircling reefs round these groups : yet it is known that coral occurs abundantly close in shore. Here, then, accord- ing to the theory, there are no proofs of subsidence ; and in conformity to this we find in the works of Forster, Lesson, Labillardiere, Quoy, and Bennett, constant allusion to the masses of elevated coral. These islands form, therefore, a well-determined band of elevation : between it and the great area of subsidence first mentioned there is a broad space of sea irregularly scattered with islets of all classes ; some with proofs of recent elevation and merely fringed by reefs ; others encircled; and some lagoon islands. One of the latter is described by Captain Cook as a grand circle of breakers without a single spot of land ; in this case we may believe that an ordinary lagoon island has been recently submerged. On the other hand, there are proofs of other lagoon islands having been lifted up several yards above the level of the sea, but which still retain a pool of salt water in their centres. These facts show an irregular action in the subteri'anean forces ; and when we remember that the space lies directly between the well-marked area of elevation and the enormous one of subsidence, an alternate and irregular movement seems almost probable. To the westward of the New Hebrides line of elevation we have New Caledonia, and the space included between it and the Australian barrier, which Flinders, on account of the number of reefs, proposed to call the Corallian Sea. It is bounded on two sides by the grandest and most extraor- dinary reefs in the world, and is likewise terminated to the northward by the coast of Louisiade, — most dangei'ous on account of its distant reefs. This, then, according to our theory, is an area of subsidence. I may here remark, that as the Barrier is supposed to be produced by the subsidence 2 o 2