Kyokubumasei-sekifu (edge-ground stone axe) (局部磨製石斧)

Kyokubumasei-sekifu is a edge-ground stone axe which appeared in the early upper Paleolithic period about 30 thousand years ago. It is thought to have been used for multiple purposes such as for hunting and demising large-sized animals, felling and cutting trees, and digging.

Such stone materials as obsidian, shale, chart, sanukite, and pyroxene were used.

The artifacts from Japan are considered to be the oldest ones in the world among the artifacts of this age unearthed so far. Kyokubumasei-sekifu were first discovered in 1949 when they were unearthed at the Iwajuku Archeological Site, and this finding sparked a controversy over whether the Paleolithic Period had in fact existed, which in turn resulted in the development of the theory that pottery had not been used in the Neolithic Period and the theory of the Mesolithic Period; there was even a dispute as to whether the abrasion of the stone tools was genuine. After that, about 650 of the artifacts were unearthed at 100 sites in Kanto and Chubu regions and other areas except Hokkaido. Most of them were hand axes and it is highly possible that they were used for smashing bones and tanning rather than wood processing. About 250 of them have been unearthed from the remains near Lake Nojiri.

The only example outside Japan is the blade stone axe of 25,000 years ago unearthed from Vollendorf site in Australia, although there are some reports on the unearthed axes from Kostenki (about 14,000 years ago) and Afontova Gora (about 20,000 years ago) in Russia, Nawamoyn (about 21,500 years ago) and Malanganger (about 29,000 years ago) in Australia. The artifacts unearthed in Kostenki caused a debate in Japan as well as to whether the shape of the artifacts had been deliberately formed by grinding in a production process or it was a result of abrasion caused by use. The materials from Afontova Gora are those collected from the surface of the ground. Although the two examples found in Australia were reported to have grooves, it is difficult to identify the ground facets from the measurement chart of the stone tools. More examples and the enhanced data of this stone tool, especially those of overseas are needed for the future studies.