Dating Sue Ware Kilns Using Geomagnetic Secular Variation: A Preliminary Study at the Sawagumi Archaeological Site, Shiga Prefecture

Yuhji Yamamoto

This seminar presented a preliminary archaeomagnetic analysis of three Sue ware kilns at the Sawagumi archaeological site in Otsu City, Shiga Prefecture. The study examined whether geomagnetic directions recorded in fired clay could be used to evaluate the operational ages and sequence of the kilns. When a kiln floor cools after firing, it acquires a remanent magnetization aligned with the geomagnetic field at that time. Comparing this direction with a geomagnetic secular variation curve can therefore provide chronological information.

The presentation outlined the analytical process, from oriented sampling of fired clay to specimen preparation, stepwise alternating-field demagnetization, and determination of remanent magnetization directions. The preliminary results showed that directional changes among the three kilns were broadly consistent with the operational sequence inferred archaeologically from excavated artifacts. However, further measurements are needed because the present analysis is based on a limited number of samples.

The discussion focused on the interpretation of differences in archaeomagnetic directions among the kilns, possible causes of discrepancies between the direction obtained from one kiln and that expected from the secular variation curve, and the sampling method and sample portions used for directional analysis.

Acknowledgments: We sincerely thank Kosuke Yamazaki of the Cultural Property Protection Division, Citizens’ Affairs Department, Otsu City; Tatsuo Nakakubo of Osaka University; and the TranSEHA Archaeomagnetism Research Group for their contributions to sampling, magnetic analysis, and archaeological interpretation.