出雲平野中央部小山遺跡における地質層序と古環境

Some researches on paleoenvironment have been carried out by using the method of ash stratigraphy and facies analysis of core data drilled in Izumo coastal plain, southwest Japan.
In this paper, we discuss on the stratigraphy and paleoenvironment of the Oyama archaeological site, central Izumo plane based on the sedimentary facies, ^14C age, pollen analysis and diatom analysis.
The followings are clarified :
(1) This area is underlain by Tsunoi-tephra.
(2) Slightly elevated mounts in this area were composed of the 1st fluvial sand layer, or 2nd fluvial sand layer.
(3) The groundwater level around this area in 4800y.B.P. was about ± 0m, and reedy marsh with Alnus trees in the near area was expanded.
(4) 1300 years ago, the river improvement in this area was finished, then it became to marsh. Soon after, the marsh was reclaimed to a paddy field.