Page:Japan by the Japanese (1904).djvu/484

The geological formation of the Japanese islands may be described briefly as follows: In the sedimentary formations those belonging to the Archæan are gneiss and crystalline schist systems, which are distributed over about 3.78 per cent. of the total area; those belonging to the Palæozoic are the Triassic, Jurassic, and Cretaceous systems, forming about 7.95 per cent.; and those belonging to the Kainozoic are the Tertiary and Quaternary rocks, forming 45.84 per cent., or nearly one-half of the total area. In the igneous rocks, those belonging to the older periods are granite, quartz, diorite, gabbro, diabase, porphyry, and porphyrite, which cover 11.27 per cent. The eruption of granite is especially prominent in the formation. Those belonging to the younger periods are andesite basalt, and liparite, which form 20.92 per cent.

Nothing accurately is known of the origin of the Japanese mining industry, but it is a matter of record that as early as the seventh and eighth centuries gold, silver, copper, iron, coal, and petroleum were produced.

During the fifteenth century many mines were opened, but the workings were carried on on a small scale, and attracted little attention. The tools consisted of a hammer and a small wedge. A drift was generally driven on a mountain-side or in a valley, and the ores were mined from outcrops and along the vein. So narrow and winding were the mine roads that workmen going single file walked with difficulty. Small timber supports were used to sustain the roof and sides, while in lieu of ladders were upright timbers serrated to facilitate climbing. Under such conditions, the ventilation and drainage were so bad as frequently to extinguish the lights, but so little did the miners appreciate the danger, that they were