344 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 beyond 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 fromthe 
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. 
