The paleomagnetic measurement is used to identify two subtimes: Biwa reverse polarization No. 1 and Biwa reverse polarization No. 2, and also to identify the late Middle Pleistocene.

• 冲洪积层中部的热释光年龄为 (30 2± 2 2 )ka ；古地磁测量确定出琵琶反向极性 1和琵琶反向极性 2两个亚时 ；时代为中更新世晚期 .