The mediating effect of platform width on the size and shape of stone flakes

To understand the ways in which past stone knappers controlled the morphology of the flakes they produced, archaeologists have focused on examining the effects of striking platform attributes on flake size and shape. Among the variables commonly considered, platform width has routinely been noted to correlate with flake size and hence used to explain past knapping behaviors. Yet, the influence of platform width on flake variation remains equivocal due to the fact that the attribute is not under the direct control of the knapper. Instead, platform width tends to be treated as a by-product of other independent knapping parameters, such as platform depth. In this study, we hypothesize that platform width acts as an intermediary that intervenes the effect of other independent variables on flake attributes. By analyzing experimental flakes produced under both controlled and replicative settings, the results support the hypothesis that platform width mediates the effect of platform depth on flake width, such that flakes with relatively larger platform widths are generally wider but no longer. This finding provides a way to incorporate platform width into discussions of the interrelationships among knapping variables, and highlights the importance of platform width for investigating how past knappers controlled flake production through platform manipulation

A Synthesis of the Dibble et al. Controlled Experiments into the Mechanics of Lithic Production

Archaeologists have explored a wide range of topics regarding archaeological stone tools and their connection to past human lifeways through experimentation. Controlled experimentation systematically quantifies the empirical relationships among different flaking variables under a controlled and reproducible setting. This approach offers a platform to generate and test hypotheses about the technological decisions of past knappers from the perspective of basic flaking mechanics. Over the past decade, Harold Dibble and colleagues conducted a set of controlled flaking experiments to better understand flake variability using mechanical flaking apparatuses and standardized cores. Results of their studies underscore the dominant impact of exterior platform angle and platform depth on flake size and shape and have led to the synthesis of a flake formation model, namely the EPA-PD model. However, the results also illustrate the complexity of the flake formation process through the influence of other parameters such as core surface morphology and force application. Here we review the work of Dibble and colleagues on controlled flaking experiments by summarizing their findings to date. Our goal is to synthesize what was learned about flake variability from these controlled experiments to better understand the flake formation process. With this paper, we are including all of the data produced by these prior experiments and an explanation of the data in the Supplementary Information