A record of the secular variation of the geomagnetic field for the last 11000 years has been obtained from the remanent magnetization of seven wide-diameter (20 cm) cores of marine and lacustrine sediment from central to south-west Japan. Magnetization directions of five cores, possessing high-amplitude variations, exhibit good correlation. Two cores show lowamplitude variations, but they can be correlated well with other records after deconvolution to remove filtering effects of the post-depositional magnetization process. A composite secular variation curve was constructed by stacking the field direction records. Time constraints were obtained from radiocarbon ages of shell and wood fractions or tephrochronology. The secular variation curve agrees well with the archeomagnetic record after 1400 yrBP, with a slight difference in the time range 1400-2000 yrBP. The secular variation for the last 11000 years shows an elongated distribution of VGP's. The azimuth of the elongation, about 40°E, is consistent with that of VGP's from Japanese volcanic and sedimentary rocks during Brunhes epoch. The angular standard deviation is 14.5° (upper limit = 15.4°, lower limit = 13.7°). This estimate is slightly larger than that observed globally during Brunhes epoch and the position of the average VGP deviates 8.5° from the geographic north pole. These VGP analyses suggest a stationary nondipole source. The secular variation records from five northern hemisphere sites between 135°E and 95°W in longitude possess a single prominent feature: an extreme easterly swing in declination. A plot of age versus longitude of the swing at each site shows a clear westward drift, at a rate of about 0.13° /yr. The field vector around the swing represents clockwise looping at all the sites. This suggests that the swing is caused by a large non-dipole source which drifts at least from 135°E to 95°W in longitude.

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A palaeomagnetic study has been carried out on three stalagmites from two limestone caves in SW Japan. Remanent magnetizations of the stalagmite samples are weak, but stable enough to record the geomagnetic field. The results indicate an internal consistency between several time-equivalent samples drilled from the same stalagmite. A tentative correlation is suggested between palaeomagnetic data from two stalagmites collected from the same cave, and data from two different limestone caves. Combined curves of declination and inclination variations are constructed on the basis of this tentative correlation between the alternatingfield cleaned results from the three stalagmites. These variation curves can also be tentatively correlated with those deduced from archaeomagnetic studies in SW Japan. In consequence, the curves are believed to represent records of past geomagnetic secular variation. The tentative age of the oldest end of this secular variation curve can be estimated at about 15 OOO yr BP, based on the correlation with the archaeomagnetic results. A possible long period of westerly declination and steep inclination is recognized in the older part of the variation

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