Notes on the Geology of Japan

Abstract

O ne of the first published accounts of the geology of Japan is contained in the paper read by Baron von Richthofen before the Geological Society of Berlin in 1873. That author stated his belief that the backbone of the Japanese islands was formed by three systems of mountain-ranges composed chiefly of Silurian and Devonian strata accompanied by granite. The first and main system, of which the axis trends from W. 30° S. to E. 30° N., extends through the island of Kiushiu, and afterwards continues up to the great bend in Nippon, the largest island of the group. This first system is intersected at either end by another which runs S.S.W. to N.N.E. On the west it commences in Kiushiu and extends southward in the direction of the Liukiu Islands, whilst on the east it constitutes the northern branch of the main island, and with a slight deviation in its course continues through the islands of Yesso and Saghalien. A third system, not properly belonging to Japan, is indicated by the S.W. and N.E. line of the Kuril Islands. The first system, where it occupies the country for itself alone, is comparatively free from volcanoes; the second is accompanied by volcanoes; but the greatest accumulation of volcanic rocks as well as extinct volcanoes is found in the places of intersection, or those regions where the lines of two systems cross each other, and also in that region where the third system branches off from the second. Amongst the details regarding