Abstract
We carried out a phytolith analysis of the Late Pleistocene tephra-soil sequence containing burned erect trunks, the so-called “Noboribetu Petrified Forest”, around the Kuttara volcano located in the southwestern part of Hokkaido to assess the existence of the Sasa group (dwarf bamboo). Sasa phytoliths disappeared from soils directly overlying the Kuttara-5 tephra deposit (Kt-5) in the middle Marine Isotope Stage (MIS) 5a. This suggests that the disappearance of Sasa from the floral community around the Kuttara volcano occurred from the late part of MIS 5a. The “Noboribetu Petrified Forest” was embedded in three tephra deposits derived from the Kuttara volcano, Kuttara-1 (Kt-1), Kuttara-3 (Kt-3), and Kuttara-4 (Kt-4), between the later part of MIS 5a and the early part of MIS 3. Thus, the result shows that the “Noboribetu Petrified Forest” was a coniferous forest without Sasa.
