Abstract
A newly discovered sandy lacustrine deposit containing a fossil forest has been found within the valley floor of a branch of the Tadami River, at an altitude of 367 m above sea level (a.s.l.). Fossil trunks in this area yield a 14C age of 48,180 ± 580 yBP, suggesting that this area hosted a dammed lake generated by the Mizunuma eruption of Numazawa volcano, located some 35 km downriver of the fossil forest. Although a 14C age of 45,000 yBP has been reported for the Mizunuma eruption, this age should be revised to >43,500 yBP to correct for errors in the original analysis. This indicates a calendar age for the Mizunuma eruption of ca. 53 ka, consistent with the stratigraphic age of the Daisen-Kurayoshi tephra that immediately overlies the Mizunuma pyroclastic deposit.
