抄録
Paleomagnetism and K-Ar ages of two successive lava flows from Kita-Matsuura, northwestern Kyushu were studied in attempting to estimate the time required for the geomagnetic field to switch from one polarity to the other. Both lava flow successions record normal and reversed polarities. K-Ar ages of these flows range from 7m. y. to 10m. y. However, because of inconsistensies within a flow and among successive flows, K-Ar ages should be regarded as indicating approximate ages of these lava flows. Hence, it was not possible to determine the transition time for the geomagnetic field switching.
