Stratigraphy of the Late Pleistocene and the Holocene and sedimental environment in the Uwajima Lowlamd,Ehime Prefecture,soutywest Japan

摘要

In the Uwajima Lowland,locates in the western part of the Shikoku Island,the Late Pleistocene and the Holocene sediments are divided into the Uwa Kai and the Uwajima Formations.Bunkyo-cyo and Uwajima 1 Volcanic Ashies found in the upper part of the Uwa Kai Formation and Uwajima 2 Volcanic Ash inthe lower part of the Uwajima Formation can be correlated with Kuji-Handa Pyroclastic Flow Deposit,Aira-Tn and Kikai-Akahoya Volcanic Ashers Respectively.The upper part of the Uwa Kai Formation deposited before 80ka and after 26ka of the Late Pleistocene as non-marine sediment.The Uwajima Formation was formed during the Holocene.At first,the lowermost Uwajima-koh Sand and Mud Member began to deposit in drowned valley and next,the inner-bay prodelta and delta-front deposits followed during the early to middle Holocene.Sukagawa sandy Gravel Member deposited as flood plain sediments.Tatsunogawa and kandagawa Sandy Gravel member formed as fan deposites,Two sandy gravel members hed been fomed since 3ka.