Pollen Analysis and Dates of the Upper Pleistocene Deposits near Towada Caldera, Akita Prefecture

Abstract

The Kosaka pumice-flow deposits resulting in the older depression of the Towada caldera, are distributed typically near Kosaka, Akita prefecture. The deposits are divided into three units: lower, middle and upper. Each of these deposits lies on a gravel bed with a thin peat-seam.Dates of the deposits were measured by the carbon of the materials from the pumiceflow and the peatseams, and the floras from the peatseams were palynologically investigated. The present locality is situated in the deciduous forest zone. The result are as follows:Upper: 1) Date, 14C-years B. P. 10, 400±200, 2) Flora, subalpine coniferous elements, 3) Climate, cold (the reduction is 5°-9°C as compared with the annual average of temperature of this district).Middle: 1) 12, 000±250, 2) subalpine coniferous elements, 3) cold (5°-9°C).Lower: 1) >33, 000, 2) subalpine coniferous-deciduous (Fagus) elements, 3) cool (about 4°C).