0)1 the Formation and Growth of Coral Reefs and Islands. 53 



expired ? — so long since^ that we have no historical record of their exist- 

 ence, and yet we have ample ocular proof of such having been the case, 

 strengthened by the fact of a few remaining in actual operation. Also 

 taking into consideration the positive evidence of the greater portion of 

 our present dry land having been suljmerged, and whether at that time 

 Europe "must not have been similarly situated with that portion of the 

 Pacific to which we have now been directing your attention. Comparing 

 the Apeninnes or Jura chain of mountains, or if you please, the colossal 

 Andes, with the coral chain or reef of New Holland, the western isles of 

 Scotland, with the islands cT Tahiti, &c. ; the extinct volcanoes of Auvergue, 

 with the circular coral lagoon isles of the Paumotas ; and there can be 

 little doubt that the analogy of circumstances will appear mucii closer than 

 it is necessary now to insist upon. As a further proof tliat the lagoou 

 islands are formed upon the edges of extinct volcanic craters. Captain 

 Beechey found lava or pumice within one of the lagoons, among the 

 Gambler isles ; and that the islands are being repeatedly raised or sunken 

 by submarine movements, is evidenced in many instances ; it will be suffi- 

 cient to show that land is raised j proof of its depression would from the 

 very circumstance of its being submerged, be more difficult, except from 

 analogy or actual observation ; still proofs of the latter are not wanting j 

 for one, take the following case, which was the topic of conversation among 

 the islanders, when the author of this memoir was among them, in 1826. 



Towards the close of the year 1825, the island of Ana, or Chain Island, 

 was devastated by a violent toerou, or westerly wind, which lasted many 

 hours J and coming from an unusual quarter, the sea broke with infuriated 

 violence on the western portion of tlie reef, carrying with it trees, huts, 

 and natives ; a few only who were fortunate enough to secure their canoes, 

 being saved, by their being drifted across the lagoon to the opposite shore. 

 In this instance it was evident, even to the natives, that the hurricane 

 alone was not sufficient to account for the violent agitation of the ocean. 

 When the sea had returned to a smooth state, it was found that a great 

 portion of the western side of the island had disappeared, and it was com- 

 puted that not less than three hundred lives were lost upon the occasion, 

 and great numbers of individuals were obliged to emigrate to the neigh- 

 bouring isles. 



Whether and how these islands are raised after their formation, is a 

 question which requires deliberate investigation, on account of the slight 

 degree of height at which the majority of them stand above the level of 

 the ocean. Our opinion is, that a gradual upraising lias in some way or 

 other taken place, and that they do not owe their present height to the 

 accidental increase upon their surface, by the debris of the outer portion 

 of the reef being washed up. 



With regard to the Hat, tabular islands, they may have been formed 

 either upon the tops of sub-marine mountains, or by the filling up of the 



