The role of platform angle and core size in hard-hammer percussion flaking
Citation: John D. Speth (1981) The role of platform angle and core size in hard-hammer percussion flaking. Lithic Technology (RSS)
Internet Archive Scholar (search for fulltext): The role of platform angle and core size in hard-hammer percussion flaking
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Summary
Context: In previous studies, Speth performed a series of experiments to see how glass prisms fractured from dropping steel balls. These experiments aimed to understand the factors of hard-hammer percussion flake production. This study furthers his previous research by investigating the effects of different platform angles and the size and shape of the glass prism.
Methods and Materials: Speth used three equilateral triangular glass prisms and three right angle triangular glass prisms and a steel ball with 1.905 cm diameter as a percussor. The percussor was dropped from a constant height of 50 cm by an electromagnet. The velocity of the percussor upon impact was approximately 313.28 cm/sec. The angle at which the percussor was dropped onto the glass prism was varied
Results: Flakes were close in resemblance particularly in shape and form even if prism size or geometry were different. The general anatomy of the flakes produced included a central spherical segment that was truncated by the striking platform. Continuing laterally on either side of the central “lens” were thin wing-like projections. Flake length increases as the distance from the prism edge increases. Speth also states that if a prism is smaller, the minimum ball diameter of the percussor increases. All flakes have a bevel to their edges and this made measuring the flake width difficult, however, the flake width was highly variable for all prism sizes. Speth measured the three common ratios of length/width, length/platform thickness, and width/platform thickness. From the first two ratios respectively Speth concluded that right angle prism flakes are shorter per unit width than their equilateral counterparts and for equilateral prisms, flake length and width are greater per unit of platform thickness compared to right angle prism flakes.
Theoretical and Practical Relevance
Connection: Results from this study show that the size of the specimen is important in determining the size of the flakes that can be produced from hard-hammer percussion. These experimental results can help inform archaeologists who are trying to determine the manufacturing process of prehistoric stone artifacts in the context of a given site. However, Speth states that more experimentation would be needed to determine the strength of the relationship between the size and shape of percussion flakes and the effects of phenomenon tested in this study.
Judgement: Speth was very informative in his explanation of his experimental results. However, I would have preferred more detail in his methods section in the event that I would like to replicate the experiment myself.
