Stone tools resembling a knife (ナイフ形石器)
Stone tools resembling a knife were characteristics to the end period of the Paleolithic period, and they were made by blunting and exfoliating flakes like stone knives (blades) (i.e. Exfoliation was adjusted so that the sharp edge of flake would be partly remained like a knife blade and the rest of the edge would be blunted), and by forming the flakes into a shape similar to modern knives. Sharp-ended stone tools resembling a knife are often categorized as point in abroad, however, in Japan they are separated from double-edged spear points and only single-edged tools are referred as stone tools resembling a knife.
Stone tools resembling a knife appeared in accordance with the generalization of stone knife techniques, and there are piercing type with sharp blade and edge like a small cutting knife and cutting type like a box cutter. The former type included hunting tools like spear head, and the most of the latter type were used as working tools. They were used to cut fur, meat or bark, and much sharper than the blade of ground stoneware.
Stone tools resembling a knife were developed uniquely in the Japanese Islands and have not been found in the Asian Continent. However, flake points (a kind of stone tool resembling a knife) have been found in areas from Kyushu to the Korean Peninsula.
The period when these stone tools were mainly used for production activities is called 'cultural period of stone tools resembling a knife,' which lasted from 30,000 to 14,000 years ago. At the end of this cultural period (1.5 year ago or before), stone spear points appeared around Kanto and Chubu region. Eventually they surpassed stone tools resembling a knife.
Stone tools resembling a knife are categorized into the following types according to the period or region that they were made or used, the nature of the materials of flake, the parts blunted and exfoliated, or the difference of overall shapes.
Higashiyama type: Tohoku region
Sugikubo type: Vertical stone knife which top-end and base is blunted; distributed mainly from the northern part of Chubu region to Tohoku region
Moro type: Vertical stone knife which edge and the base of the opposite side is blunted; distributed mainly in Kanto region, the southern part of Chubu region and Tokai region
Ko type: Horizontal stone knife (wing-shaped flake) which has one blunted edge; distributed mainly in Setouchi, Kansai, Chugoku and Shikoku regions
Kyushu type: Basically same as Moro type, but smaller; distributed in Kyushu region
In addition, increasing number of samples has been discovered in Hokkaido Prefecture. There have been evidences in various places that show these regional differences were formed before Aira-Tn ash fall.
In addition, stone tools resembling a knife play a key part to examine the time division and the cultural development stages of the Paleolithic period, along with points and microliths.