and Iceland.  Both geologic histories involve high reliefs, steep slopes, a deep surrounding sea, and hence rarely a shallow continental shelf for the accumulation of broad alluvial lowlands.  Among the Aegean Isles only Naxos has a flood plain; all the rest have steep coasts, with few sand or gravel beaches, and only small deposit plains at the head of deep and precipitous embayments.  Japan’s area of arable soil is to-day only 15.7 per cent. of its total surface, even after the gentler slopes of its mountains have been terraced up two thousand feet.  Some authorities put the figure lower, at 10 and 12 per cent.

[Sidenote:  Dense populations of islands.]

Yet in spite of limited area and this paucity of local resources, islands constantly surprise us by their relatively dense populations.  More often than not they show a density exceeding that of the nearest mainland having the same zonal location, often the same geologic structure and soil.  Along with other small, naturally defined areas, they tend to a closer packing of the population.  Yet side by side with this relative over-population, we find other islands uninhabited or tenanted only by sheep, goats and cattle.

In the wide Pacific world comprising Australia and Oceanica, islands take up fifteen per cent. of the total land area, but they contain forty-four per cent. of the population.[932] The insular empire of Japan, despite the paucity of its arable soil, has a density of population nearly twice that of China, nearly three times that of Korea, and exceeding that of any political subdivision of continental Asia; but Japan, in turn, is surpassed in congestion only by Java, with a density of 587 to the square mile,[933] which almost equals that of Belgium (643) and England (600).  Great Britain has a density of population (453 to the square mile) only exceeded in continental Europe by that of Belgium, but surpassed nearly threefold by that of the little Channel Isles, which amounts to 1254 to the square mile.[934] If the average density of the United Kingdom is greatly diminished in Ireland, just as Italy’s is in Sardinia and France’s in Corsica, this fact is due primarily to a side-tracked or overshadowed location and adverse topography, combined with misgovernment.

If we compare countries which are partly insular, partly continental, the same truth emerges.  The kingdom of Greece has fifteen per cent of its territory in islands.  Here again population reaches its greatest compactness in Corfu and Zante, which are nearly thrice as thickly inhabited as the rest of Greece.[935] Similarly the islands which constitute so large a part of Denmark have an average density of 269 to the square mile as opposed to the 112 of Jutland.  The figures rise to 215 to the square mile in the Danish West Indies, but drop low in the bleak, subarctic insular dependencies of Greenland, Iceland and the Faroes.  Portugal’s density is tripled in the Madeiras[936] and doubled in the