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Show 548 KEELING ISLAND. April, 1836 one direction over a wide area, causes breakers, which even exceed in violence those of our temperate regions, and which never cease to rage. It is impossible to behold these waves without feeling a conviction that an island, though built of the hardest rock, let it be porphyry, granite, or quartz, would ultimately yield and be demolished by such irresistible forces. Yet these low, insignificant coral islets stand and are victorious : for here another power, as antagonist to the former, takes part in the contest. The organic forces separate the atoms of carbonate of lime one by one from the foaming breakers, and unite them into a symmetrical structure. Let the hurricane tear up its thousand huge fragments ; yet what will this tell against the accumulated labour of myriads of architects at work night and day, month afte~ month. • Thus do we see the soft and gelatinous body of a polypus, through the agency of the vital laws, conquering the great mechanical power of the waves of an ocean, which neither the art of man, nor the inanimate works of nature could successfully resist. We did not return on board till late in the evening, as we staid some time in the lagoon collecting specimens of the giant Chama, and looking at the coral fields. Near the head of the lagoon I was much surprised to find a wide area, considerably more than a mile square, covered with a forest of branching coral, which though standing upright was all dead and rotten. At first I was quite at a loss to understand the cause ; afterwards it occurred to me that it was owing to the following rather curious combination of circumstances. It should, however, first be stated, that corals are never able to survive even a short exposure in the air to the sun's rays, so that their upward limit of growth is determined by that of lowest water at spring tides. It appears from some old charts, that the long island to windward was formerly separated by wide channels into several islets ; this fact is likewise indicated by the less age of the trees in· certain portions. Under this former condition of the reef, a strong breeze, by throwing more water over the barrier, would tend to raise April, 1836. FIELDS OF DEAD CORAL. 549 the level of the lagoon. Now it acts in a directly contrary manner; for the water, not only is not increased by currents from the outside, but is blown outwards by the force of the wind. Hence, it is observed, that the tides near the head of the lagoon do not rise so high during strong breezes as on ordinary occasions. This difference of level, although no doubt very small, has I believe caused the death of those coral groves, which under the former condition of things had attained the utmost possible limit of upward growth. A few miles north of Keeling there is another small lagoon island1 the centre of which is nearly filled up. Captain Ross found in the conglomerate of the outer coast a well rounded fragment of greenstone, rather larger than a man's head; he and the men with him were so much surprised at this, that they brought it away and preserved it as a curiosity. The occurrence of this one stone, where every other particle of matter is calcareous, certainly is very puzzling. The island has scarcely ever been visited, nor is it probable that a ship had been wrecked there. From the absence of any better explanation, I came to the conclusion that it must have come there entangled in the roots of some large tree: when, however, I considered the great distance from the nearest land, the combination of chances against a stone thus being entangled, the tree washed into the sea, floated so far, then landed safely, and the stone finally so embedded as to allow of its discovery, I was almost ashamed of imagining a means of transport so improbable. It was therefore with great interest that I found Chamisso,* the justly distinguished naturalist who accompanied Kotzebue, stating that the inhabitants of the Radack Archipelago, • Kotzebue's first voyage, vol. iii., p. 155. It is said, " The sea throws up on the reefs of Radack the trunks of northern firs (I) and trees of the torrid zone (palms, bamboos). It provides the inhabitants not only with timber for boats, but it also brings them in wrecks of European ships, the iron which they want."-" They receive, in a similar manner, another treasure, hard stoneS: fit for whetting. They are sought for in the roota and hollows of the trees which the sea throws up." |