Paleomagnetic measurements were made on the early Miocene marine sediments in the Chichibu Basin of the Kanto Mountains, Central Japan. The mean paleomagnetic direction, D=94°, I=53° (α95=8.3°), indicates that the Kanto Mountains have not changed their latitude significantly, but have rotated clockwise through about 90° since the middle Miocene. The rotation can be explained by the opening of the Japan Sea and the collision of the Tanzawa Block.
