308 CORALS AND CORAL ISLANDS. 



is low, with large reefs ; Duff's Islands have bold summits 

 with wide reefs. 



New Caledonia, and the northeast coast of New Holland, 

 with the intermediate seas, constitute one of the grandest reef- 

 regions in the world. On the New Caledonia shores (p. 134), 

 the reefs are of great width, and occur not only along the 

 whole length of the western coast, a distance of 200 miles, but 

 extend to the south be} 7 ond the main land 50 miles, and north 

 150 miles, making in all a line of reef full 400 miles in length. 

 Toward the north extremity, however, it is interrupted or bro- 

 ken into detached reefs. This surprising extent is partly ex- 

 plained by the fact that New Caledonia is not a land of vol- 

 canoes ; but on the contrary consists of older metamorphic 

 rocks. The streams of so large a land might be expected to 

 exclude reefs from certain parts : and in accordance with this 

 fact, we find the reefs of the windward or rainy side compara- 

 tively small, and scarcely indicated on the charts ; while on 

 the dry or western side, they often extend thirty miles from the 

 shores. The theory of subsidence accounts fully for the great 

 prolongation of the New Caledonia reefs. The reefs indicate 

 moreover, the existence of a former land near three times the 

 area of the present island. 



Between New Caledonia and the New Hebrides are sev- 

 eral high islands, one of which, Lafu, has been described 

 (Quart. J. Geol. Soc, 1847, p. 61) by Rev. W. B. Clarke as 

 an elevated coral island, with fringing reefs ; it appears also 

 from the remarks of this writer, that the other islets of what 

 is called the Loyalty Group, are of the same kind. Lafu, the 

 largest of the number, is about ninety miles in circumference. 



South of New Caledonia lies Norfolk Island, in latitude 

 29° S., about which there is said to be some coral, which is 

 occasionally thrown on the beach, but no reefs. 



