Table 3 Tephra ages used as time references for δ¹⁸O isotope stratigraphy. The estimated age, method of age determination, and references are given for each tephra age

Ata-Th

0.238 (MIS 8.0)

Comparison of pollen and diatom records on the Lake Biwa sediments with marine oxygen isotopic records

(Kuwae et al. 2002; Nagahashi et al. 2004)

Aso1

0.249 (MIS 8.2)

Comparison of pollen and diatom records on the Lake Biwa sediments with marine oxygen isotopic records

(Kuwae et al. 2002; Nagahashi et al. 2004)

BT72

0.349 (MIS 10.3)

Comparison of pollen and diatom records on the Lake Biwa sediments with marine oxygen isotopic records

(Kuwae et al. 2002; Nagahashi et al. 2004)

Hkd-Ku

0.75 (MIS 19.1–18.4)

Comprehensive estimation of the Fission track age, K-Ar and stratigraphy of the Osaka Group

(Nagahashi et al. 2015; Suzuki et al. 2005)

SS-Az

0.85

Biostratigraphy, isotope stratigraphy

(Pickering et al. 1999; Hayashida et al. 1996)