Obsidian Provenance Analysis
Obsidian, a volcanic glass primarily made of rhyolite, has been extensively utilized as a material for crafting stone tools globally since the Palaeolithic era due to its ability to create sharp edges upon fracture. Although obsidian is limited to certain volcanic regions, archaeological sites in distant areas have yielded numerous obsidian tools. This has intrigued archaeologists, as obsidian serves as a significant material in understanding prehistoric trade, exchange networks, and interactions among ancient populations.
In the Japanese archipelago alone, obsidian can be found in over 20 major locations, or over 100 when categorized in detail. Variations in crystalline morphology and chemical composition occur among different sources due to distinct crystallization processes.
In the Japanese archipelago alone, obsidian can be found in over 20 major locations, or over 100 when categorized in detail. Variations in crystalline morphology and chemical composition occur among different sources due to distinct crystallization processes.
Provenance analysis of obsidian materials from the Iyai rock shelter site using this method yielded insightful results. The analysis conducted in 2017 (the middle and latter parts of the Initial Jomon period) and in 2019 (Oshigatamon phase in the terrace area and chinsenmon phase in the rock shelter area) consistently revealed the presence of both Kofukasawa (Wada pass type) and Hoshigato (Suwa type) obsidian across all periods and locations. This discovery suggests that the inhabitants of the Iyai rock shelter site likely expanded their territorial reach to an obsidian production center situated more than 60 kilometers away. Presumably, they obtained obsidian while hunting on the Kirigamine Plateau, an area that extends into the source region. This method of acquiring stone is recognized as an embedded strategy and persisted until the conclusion of the Initial Jomon period. However, from the Early Jomon period onwards, the majority of obsidian was acquired from specific sources.
Yutaka Daikuhara
Miura Maiko
Tateishi Toru
Shuji Ninomiya