Abstract
This paper discusses the theoretical framework of identification of flaking techniques based on the fracture mechanics of brittle solids, and presents the results of a series of experiment which examined a criterion of identification applicable to the archaeological records. The term ‘flaking technique’ is used in conjunction with knapping materials (stone, metal, antler, wood) and knapping techniques (direct percussion, indirect percussion, and pressure).
To address this issue, we focus on fracture wings, which are microscopic markings found on the fracture surfaces of a wide range of brittle solids including obsidian. Fracture wings are ubiquitous and very reliable registers of crack velocity. Identification of flaking techniques is divided into two processes: (1)identification of crack velocity based on the model of fracture mechanics, (2) a strong correlation between crack velocity and flaking techniques that is experimentally recognized. Our several experiments demonstrate that a strong association between crack velocity and flaking techniques does in fact exist. Through the analyses of fracture wings, we establish three groups of flaking techniques (I: pressure, II: indirect percussion, direct percussion using antler or wood, III: direct percussion using stone or metal), which are strongly dependent on the difference in crack velocity. This result makes it possible to identify the flaking techniques in the archaeological records, and should contribute to the understanding of the processes involved in flaking formation.
