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 



