Human activity patterns at the Horokazawa Toma Upper Paleolithic stone tool manufacturing site in the Shirataki obsidian source area: Combining excavation with experimentation

The obsidian came from the East Atelier and Ajisainotaki (especially) sources near the summit of Mt. Akaishiyama. Large angular and slab-like nodules from these sources were likely collected at Hidarinosawa being closer to HT, brought to HT, and processed into large bifaces and boat-shaped blanks for microblade manufacture. Many of these products were exported to other sites. We showed by experiment that the first and second spalls efficiently removed from a large biface by the block-on-block technique. A similar microblade industry based on Shirataki obsidian is found at sites in the Yubetsu River drainage, below HT, and other sites in Hokkaido. In fact, Shirataki obsidian is found at remote sites such as Akatsuki site (eastern part of Hokkaido) and Sokol site (on Sakhalin island), suggesting that raw materials were exchanged between groups of people over long distances. This large distribution network was supported by mass production of blanks for microblade manufacturing at the Toma locality of the Horokazawa site.