JAPAN five large and four thousand small islands which form the nucleus of the Empire of Japan are the remains of a great mountain system lying off the east coast of Asia, with which they were once connected. Their total area is about 161,000 square miles, or one and a third that of the British Isles. The largest is Honshiu, which contains about 54 per cent. of the total extent of the country, and is the centre both of its political and economic development. The physical configuration and structure of this island are extremely complicated. The general trend of the mountains is N.N.W. in the northern half, and W.S.W. in the southern, but in the vicinity of the great rift valley, which runs across the middle of the island from north to south, they bend round towards the zone of fracture, thus giving rise to a number of meridional ranges in central Honshiu. In the northern part of the island the main range consists of granitic rocks overlain by volcanic outpourings, while further to the east are ranges composed of schists and sedimentary rocks, and to the west numerous volcanic mountains. To the west of the rift valley there appear in south Kiushiu, in Shikoku, and in the Kii peninsula, folded sedimentary rocks, behind which are the southern schist mountains. Further north, the islands of the Inland Sea are mainly granitic, as is the case with the mountains of Honshiu, lying immediately to the north of that sea, while beyond these again there are volcanic mountains. Between these different mountain ranges and along parts of the coast, there lie numerous plains of recent origin, the most important being the Kitakami plain between the central and eastern ranges of the north, the plain of Echigo on the west coast, the Kwanto plain, the largest in the country, round Tokio, the Mino-Owari plain to the west of the meridional mountains in central Honshiu, and the Kinai plain, which contains the cities of Kyoto and Osaka. In Shikoku there are several plains of limited extent, while in Kiushiu the most important is that of Tsukushi in the north of the island.
Of the other parts of the country, Yezo, renamed the Hokkaido, is very mountainous, owing to the fact that two ranges appear to cross one another, the schist range of Sakhalin and the volcanic range of the Kuriles. Formosa, acquired from the Chinese in 1895, is somewhat larger than Kiushiu. A high mountain range composed of ancient rocks extends along the eastern part of the island, while the west consists generally of an undulating, fertile plain of Tertiary and later times.
CLIB1ATE.—The climate of the Japanese Islands shows consider able variations from north to south and from east to west. This is due to a combination of circumstances—the great latitude over which the islands extend, their position with regard to the Asiatic land mass, and the influence of the sea with its warm and cold currents.
The heat of summer and the cold of winter are alike less extreme than on the corresponding parts of the coast of Asia. The warm Pacific current, or Kuro Siwo, bifurcates to the south of Japan and washes both its eastern and western shores. The eastern and stronger branch follows the direction of the coast as far as latitude 38° N., after which it bears away across the Pacific, while the western and weaker branch enters the Sea of Japan by the Tsushima Strait, and leaves it by La Perouse and Tsugaru Straits in the north. At the same time, one cold current from the north passes
along the eastern coasts of Hokkaido and Honshiu as far as latitude 89° N., while another passes along the western coast until it is lost in the warm current moving from the south. The warm currents tend to raise the temperature, especially on the east coast, during the winter months, and the proximity of the sea reduces it in summer.
The direction of the winds is another important factor in the determination of Japanese climate. During the winter, when anti cyclonic conditions prevail over the Asiatic continent, cold winds blow outward from Siberia in a south and south-easterly direction; and strike the west coasts of Japan. On the other hand, the moun tainous backbone of the country shelters the land lying to the east of it, and for this reason also the east coast is warmer than the west in winter. During the summer months Japan lies within the mon soon area, and southerly winds prevail. The heaviest rainfall, therefore, occurs at this season, although to the north-west coasts considerable precipitation is brought by the continental winds of winter which pick up moisture as they blow across the Sea of Japan.
In the Hokkaido the winter is long and cold, and during it the mean temperature is generally below zero, while in summer, in the warmer districts, it is as high as 70° F. Somewhat similar con ditions prevail in the northern part of Honshiu, though the cold of winter is less and the heat of summer somewhat greater. In south-west Honshiu, in Shikoku, and in Kiushiu, climatic conditions are much more favourable. The mean winter temperature nowhere falls much below 40° F., while in summer it is between 70° F. and 80° F. in the warmer districts. Formosa has a tropical climate except in the highlands.
The rainfall is considerable over the greater part of Japan. On the south and north-west of Honshiu it is over 60 inches, and in places over 80, while in the interior and on the north-east coast it is between 40 and 60 inches. In the Hokkaido it is generally between 30 and 40 inches, except along the north-west and south-west coasts, where it is somewhat higher. Formosa has from 80 to over 100 inches.
VEGETATION.—The forests of Japan belong to several distinct types, the distribution of each of which is determined by the climatic conditions just described. The cool temperate forest extends over Honshiu, north of the thirty-sixth parallel, and over the whole of Hokkaido. In the north of the latter island conifer alone are found but further south coniferous and deciduous trees intermingle. Among the principal species of this forest are the pine, cypress, fir, beech, walnut, and ash, and these are also found at higher altitudes further south.
Over southern Honshiu, Shikoku, and Kiushiu, the prevailing type of vegetation is the warm temperate rainforest, in which deciduous and broadleaved trees intermingle. Camphor, box wood, and several varieties of oak and pine are characteristic of the region. In Formosa the forest is tropical, and the banyan, the bamboo, and the camphor tree are among its chief products.