C-14 ages of terrace deposits at the west of Shichinohe Town, Aomori Prefecture, Northern Japan

The authors were able to collect to samples of three stratum levels for measuring age in the construction site of expanding a road in Shichinohe Town in October, 1976, when they carried out the survey of active faults in the area. In this paper, the result of observation of the outcrops at the sampling site and the measured age are reported, and the related problems are described as one of the materials for the study on the Quaternary period in this area. The topography in the vicinity of the site is explained. The state of the outcrop is shown, and humus soil layer of 60 to 80 cm thick, sand layer of 1.5 to 2 m thick, pumice flow deposit of about 2 m thick, black soil containing small wooden chips, grapy mud deposit of about 4 m thick containing many pumice pieces, bluish grapy pumice piece layer of 15 cm, and gravel layer are observed. The C-14 age of the small wooden chips was 13500 +- 240 y.B.P. The C-14 age of the wooden chips in peat over the gravel layer was 19540 +- 940 y.B.P. The pumice flow deposit seems to correspond to Hachinohe pumice layer in view of the distribution, topographic relation, and the state of production. The fine pumice piece layer seems to be the deposit in water, and the deposit of the gravel layer had finished just before the coldest period of the last ice epoch. (Kako, I.)