Ubayama Shell Mound

Located in Kashiwai-cho, Ichikawa City, Chiba Prefecture, this is a settlement site with a horseshoe-shaped shell mound dating from the middle to middle late Jomon period. It is a pure salt shell mound made up mainly of shellfish such as clams that come from the sandy and muddy bottom of an inland bay. The shell layer distribution is medium-sized, measuring approximately 130 meters east to west and 120 meters north to south. Excavations by the Department of Anthropology at Tokyo Imperial University in 1926 (Taisho 15) confirmed that Jomon houses were pit dwellings with hearths and pillars, and that they formed settlements. In addition, five human bones, including two adult men, two adult women, and one child, were discovered on the floor of one of the pit dwellings, providing material for examining issues of habitat division and family. It has been repeatedly investigated as a shell mound with a large number of human bones, and as a result, 143 human bones (including those without any skeletal remains) have been discovered, contributing to research on the characteristics and burial customs of the Jomon people. In spite of this, only 39 dwellings have been discovered (Site E has not been included). Most of these belong to the Middle Jomon period. It was designated as a national historic site in 1967 (Showa 42).

[Masayuki Horikoshi]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

千葉県市川市柏井(かしわい)町所在の縄文時代中期中葉から後期中葉までの馬蹄形(ばていけい)貝塚を伴う集落遺跡。ハマグリなど内湾砂泥底産の貝を主体とした純鹹(じゅんかん)貝塚である。貝層分布の外径は、東西約130メートル、南北約120メートルと中規模である。1926年（大正15）の東京帝国大学人類学教室による発掘で、縄文時代の家が、炉と柱をもつ竪穴(たてあな)住居であることが確実となり、しかも集落を形成することが判明した。また、1軒の竪穴住居の床に成人男性2体、成人女性2体、子供1体の計5体の人骨が発見され、住み分けや家族の問題を検討する材料を提供した。これまで人骨の多い貝塚として繰り返し調査されてきた結果、143体（個体骨格を残さぬ例も加算）の人骨が発見され、縄文人の形質や葬制などの研究に貢献している。そのわりに住居検出軒数は39軒（E地点は未加算）と少ない。これらはおもに縄文中期に属する。1967年（昭和42）国の史跡に指定された。

［堀越正行］

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