Use-wear formation processes on pounding tools: quantifying surface changes using confocal microscopy, 3D techniques and GIS

Abstract

Since the publication of the groundbreaking work produced by Sergei A. Semenov (1964), functional studies of Paleolithic artefacts based on use-wear traces have developed rapidly and have become the main method for inferring the production and use of stone tools. These types of analyses were applied to flaked artefacts, grinding tools from late prehistoric periods, and more recently, to pounding tools from Early Stone Age sites. Despite this focus on use-wear, the criteria used for describing these traces were limited to mostly qualitative attributes observed with microscopes. In this paper, we will present the results of an experimental programme designed to establish new qualitative and quantitative criteria for the recognition of bone processing activities related to marrow extraction on pounding tools from Olduvai Gorge (Tanzania). Our method to study use-wear formation processes on pounding tools (hammerstones and an anvil) is novel and based on a combination of conventional microscopy, optical 3D surface measurements obtained with a confocal microscope, and GIS analysis. This technique has allowed us to obtained high resolution quantitative data and conduct statistically robust analyses of microscopic use-wear traces highlighting the potential of implementing 3D techniques in functional studies of artefacts. Our results are broadly applicable and provide a methodological procedure that can be used for more accurate assessments of the function of archaeological pounding tools.