14C-ages and pollen analysis of the Quaternary deposits in the Obama Plain, Fukui Prefecture

The Quarternary system of the Obama Plain in Fukui Prefecture is described on the basis of 14C-dating and pollen analysis results. The Obama Plain along Kita River pouring into Obama Bay comprises alluvial flat lowland, a diluvial terrace and alluvial small fans. The subsurface Quaternary formations of the plain are Diluvium and Alluvium. For 14C-dating, samples were wood chips from the sediments of diluvial terrace and alluvial fan and peaty soil and wood chip from boring cores. For pollen analysis, samples were from boring cores. (1) Results of 14C-dating: Diluvial terrace deposit corresponds to the Tachikawa terrace deposit in south Kanto. An ancient lowland was probably under marshy condition. (2) Results of pollen analysis: Abundant products in the coniferous trees pollen are Cryptomeria etc. In the broadleaf trees pollen Salix etc. are dominant. Such as Pinus etc. are currently in the Hokuriku region; the climate in the Obama Plain was thus not different. (Mori, K.)