Geology. It is popularly supposed that Japan entirely consists, or almost entirely consists, of volcanic rocks. Such a supposition is true for the Kurile Islands, partially true for the northern half of the Main Island and for Kyūshū. But for the remainder of the country, that is, the southern halt of the Main Island and Shikoku, the assumption is quite without support. The backbone of the country consists of primitive gneiss and schists. Amongst the latter, in Shikoku, there is an extremely interesting rock consisting largely of piedmontite. Overlying these amongst the Palaeozoic rocks, we meet in many partsof Japan with slates and other rocks possibly of Cambrian or Silurian age. Trilobites have been discovered in Rikuzen. Carboniferous rocks are represented by mountain masses of Fusulina and other lime stones. There is also amongst the Palaeozoic group an interesting series of red slates containing Radiolaria.
Mesozoic rocks are represented by slates containing Ammonites and Monolis, evidently of Triassic age, rocks containing Amtnoniles Bucklandi of Liassic age, a series of beds rich in plants of Jurassic age, and beds of Cretaceous age containing Trigonia and many other fossils. The Cainozoic or Tertiary system forms a fringe round the coasts of many portions of the empire. It chiefly consists of stratified volcanic tuffs rich in coal, lignite, fossilised plants, and an invertebrate fauna. Diatomaceous earth exists at several places in Yezo. In the alluvium which covers all, the remains have been discovered of several species of elephant, which, according to Dr. Edmund Naumann, are of Indian origin. The most common eruptive rock is andesite. Such rocks as basalt, diorite, and trachyte are comparatively rare. Quartz porphyry, quartzless porphyry, and granite are largely developed.
The mineral most extensively worked in Japan is coal, large deposits of which exist in north-western Kyūshū and near Nagasaki in the south, and at Poronai and other places in Yezo at the northern extremity of the empire. Not only is the output sufficient to supply the wants of the country; foreign steamers largely use Japan coal, and considerable shipments are made all over the Far-East. The copper mines of Ashio near Nikkō, and of Besshi in Shikoku produce enormous quantities of copper, and the antimony production is among the most notable in the world. From the mine of Ichinokawa in Shikoku come the wonderful crystals of antimonite, which form such conspicuous objects in the mineralogical cabinets of Europe. There is a fair production of silver at Innai in the north and at Ikuno in Central Japan; but that of other metals is relatively small. The reports circulated from time to time of large discoveries of gold in Yezo have hitherto not been verified.
Books recommended. Die Kaiserliche Geologische Reichsanstalt von Japan, by T. Wada.—Ueber den Bau und die Entstehung der Japanischen Inseln, by E. Naumann.—Catalogue of Japanese Minerals contained in the Imperial College of Engineering, Tōkyō, by J. Milne.—Les Produits de la Nature Japonaise et Chinoise, by A. J. C. Geerts.—Bulletin of the Geological Survey of Japan.