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Updated: June 24, 2025
We left the port of Papeiti on the morning of the 17th of May, with a most favourable wind, soon passed in safety all the dangerous coral-reefs which surround the island, and in seven hours' time had lost sight of it altogether. Towards evening, we beheld the mountain ranges of the island of Huaheme, which we passed during the night. The commencement of our voyage was remarkably pleasant.
And even if their lenity could be proved, it would in no way affect my argument for the close affinity of the Papuan and Polynesian races, and the radical distinctness of both from the Malay. Polynesia is pre-eminently an area of subsidence, and its great widespread groups of coral-reefs mark out the position of former continents and islands.
The distribution, also, of the different kinds of coral-reefs, and their position with relation to the areas of recent elevation, and to the points subject to volcanic eruptions, fully accord with this theory of their origin. In the several original surveys, from which the small plans on this plate have been reduced, the coral-reefs are engraved in very different styles.
BB, The shores of the fringed island. A'A', Outer edges of the reef, after its upward growth during a period of subsidence, now converted into a barrier, with islets on it. B'B', The shores of the now encircled islands. CC, Lagoon-channel. No theory on the formation of coral-reefs can be considered satisfactory which does not include the three great classes.
Malcolmson found at Sahar low cliffs containing shells and corals, apparently of recent species. The PERSIAN GULF abounds with coral-reefs; but as it is difficult to distinguish them from sand-banks in this shallow sea, I have coloured only some near the mouth; towards the head of the gulf Mr.
Darwin did not live to bring out a third edition of his "Coral-Reefs," I know from several conversations with him that he had given the most patient and thoughtful consideration to Mr. Murray's paper on the subject.
These nulliporae, which are hard, very simply-organised sea-plants, play an analogous and important part in protecting the upper surfaces of coral-reefs, behind and within the breakers, where the true corals, during the outward growth of the mass, become killed by exposure to the sun and air.
The area over which sediment is transported from coral-reefs must be considerable: Captain Moresby informs me that during the change of monsoons the sea is discoloured to a considerable distance off the Maldiva and Chagos atolls.
Finally, if we look to other oceanic islands of about the same height and of similar geological constitution, but not encircled by coral-reefs, we may in vain search for so trifling a circumambient depth as 30 fathoms, except quite near to their shores; for usually land that rises abruptly out of water, as do most of the encircled and non-encircled oceanic islands, plunges abruptly under it.
The apparently capricious distribution, therefore, of coral-reefs, cannot be explained by any of these obvious causes; but as the study of the terrestrial and better known half of the world must convince every one that no station capable of supporting life is lost, nay more, that there is a struggle for each station, between the different orders of nature, we may conclude that in those parts of the intertropical sea, in which there are no coral-reefs, there are other organic bodies supplying the place of the reef-building polypifers.
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