Estimating original flake mass on blades using 3D platform area: problems and prospects

This study tests how well the ITMC (Initial-/Terminal-Mass Comparison) method of Clarkson and Hiscock (2011) measures reduction specifically on blades, a largely overlooked flake type in reduction measures. We demonstrate the utility of using platform area to model the extent of reduction on retouched blades. The platform areas of 124 blades were accurately measured in three dimensions using a digital scanner. A positive relationship was observed between 3D platform area and blade mass, with greater platform areas being associated with greater masses. Multivariate regression was used to strengthen the relationship between platform area and initial mass by isolating the variables of platform, termination and indentor type as well as external platform angle. As was proposed by Clarkson and Hiscock (2011), reduction intensity can be estimated by predicting initial blade mass from the relationship between platform area and mass, and comparing this to the observed mass of a retouched blade. Our analysis returned some surprising results that raise questions about the operation of fracture mechanics, particularly for punch blades and those with focalised platforms, and the suitability of the ITMC as a holistic method of flake reduction analysis.