Apaus.— Polynesia. 51 
observed that where several small islands were close together, as in the 
Gambier Islands, that a distant reef ran round the whole of the islands, and 
that these islands were themselves encireled by coral, but that the outer 
reef was much older than the inner. These are some of the facts that 
induced him to conclude that the land had slowly subsided. 
Thus if the Viti Levu, which has a reef close to the shore, were 
gradually to subside, that is to say at about one-half foot in 100 years. 
The coral reefs close to the shore would be raised to the surface by the 
polypifers during that time, and the distance from the shore would be 
increased by two or three feet. Supposing the land to sink 7,000 feet, the 
distance of the reef would then be several miles from shore, and the 
. mountainous parts alone of the island would remain, as in Tahiti. A reef 
of this kind, which rises from deep water, at a distance from the enclosed 
island, is called a barrier reef. In case Viti Levu subsided still more, the 
reef would become more distant from the remaining land, and, in time, the 
highest peaks alone would remain above the water; each of which, under 
favorable conditions, would have its own coral reef. The Gambier group 
furnishes an example of this. The last stage of subsidence leaves a shallow 
lagoon nearly encompassed by a reef. On this the waves hurl masses of 
coral broken from the reef, the wind blows together mounds of sand, and 
the sea birds find a resting place, and thus a soil is formed for plants. A 
reef of this kind, with patches of pandanus and cocoa nut growing on it is 
called an atoll. The structure is essentially the same as a barrier reef, even 
to the patches of vegetation, which also flourish on the latter. The atolls 
are, however, smaller in extent than barrier reefs, which follows from the 
statement already made that the subsiding lofty peaks become encircled by 
reefs. The atolls are thus only the monuments of extensive lands that 
once formed larger islands, or a vast continent across the Pacific. Even 
the shape of the land that existed ages ago can still be traced in the trend- 
ing of barrier reefs. At the Fijis, for instance, a distinct reef surrounds the 
two large islands of Viti Levu and Vanua Levu, and many small islands 
which were no doubt forming headlands. This reef encloses more than 
10,000 square miles, of which there is now 4,500 square miles of dry land. 
In the division of islands in the South Equatorial current, which is called 
Polynesia for distinction, the extent of surface is not much less than the 
size of Europe, but the habitable land there is not much more than half the 
area of Auckland province. A great contrast exists between the size of the 
area enclosed by atolls and the habitable land on them. Thus in the 
Paumota group, Dana estimates that there are 1,000 square miles enclosed 
at Dean Island, but only 16 square miles of habitable land. The propor- 
tion of land is greater in other atolls, and yet of ten average islands the 
