Abstract
The Koboro cave on the northern coast of the Volcano Bay in the southwestern part of Hokkaido Island is prehistoric site yielded several skeletal remains at archaeological investigation in 1952 and 1961. Only one skeleton (No. 4) of them had positive evidence of burial and stratigraphy, whereas other individuals were excavated from disturbed sediments therefore their chronology was unknown. The 2nd investigation in 2006 confirmed that an adult male without skull was buried at rock shelter to the east of the Koboro cave. In this study, we measured radiocarbon (14C) ages utilized sample from skeletal materials in order to decide their chronology and anthropological placements. However, conventional 14C ages from skeletal remains on the coast of the Volcano Bay tend to be several hundred years older than correct ages for the marine reservoir effects and regional upwelling of deep water. We evaluated the ratios of terrestrial/marine original carbon referred to stable isotopic analysis, and besides, calibrated the 14C ages of each material on the basis of the calibration program mixed IntCal09 and Marine09. It is appreciated that this procedure is effective to dating of human skeletons taken in many marine products from comparison with tephrochronology in other neighboring archaeological site, Usu-4 site. Present study indicated that most materials from the Koboro cave were placed in the Epi-Jomon period (ca 400BC–700AD) and morphology of a part of individuals was not contradictory to this finding, but individual No. 2 might date to the Satsumon period (ca 700AD–1400AD). A skeleton from rock shelter was assessed as Ainu after the latter 17th century, considered the calibrated ages, a metallic mouthpiece for smoking, and morphology of limbs, hand bones and mandible.
