A new approach to measure reduction intensity on cores and tools on cobbles: the Volumetric Reconstruction Method

Abstract

Knowing to what extent lithic cores have been reduced through knapping is an important step toward understanding the technological variability of lithic assemblages and disentangling the formation processes of archaeological assemblages. In addition, it is a good complement to more developed studies of reduction intensity in retouched tools, and can provide information on raw material management or site occupation dynamics. This paper presents a new methodology for estimating the intensity of reduction in cores and tools on cobbles, the Volumetric Reconstruction Method (VRM). This method is based on a correction of the dimensions (length, width, and thickness) of each core from an assemblage. The mean values of thickness and platform thickness of the assemblage's flakes are used as corrections for the cores' original dimensions, after its diacritic analysis. Then, based on these new dimensions, the volume or mass of the original blank are reconstructed using the ellipsoid volume formula. The accuracy of this method was experimentally tested, reproducing a variety of possible archaeological scenarios. The experimental results demonstrate a high inferential potential of the VRM, both in estimating the original volume or mass of the original blanks, and in inferring the individual percentage of reduction for each core. The results of random resampling demonstrate the applicability of VRM to non size-biased archaeological contexts.

Practical and technical aspects for the 3D scanning of lithic artefacts using micro-computed tomography techniques and laser light scanners for subsequent geometric morphometric analysis. Introducing the StyroStone protocol

“…In this fervent and stimulating research framework, the accessibility to new technologies that allow for the fast reconstruction of 3D meshes of archaeological artefacts has resulted in the application of new and powerful means of analysis. Besides the numerous papers that have explored the use of GM analysis to stone artefacts discussed in this paper, the use of 3D technology has also allowed researchers to quantify reduction intensity on cores [e.g., 68 ], accurately measure angles between surfaces of bone and stone tools [e.g., 69 , 70 ], and assess knapping skills with the use of virtual refittings [e.g., 71 , 72 ], among other applications.…”

Oldowan Technology Amid Shifting Environments ∼2.03–1.83 Million Years Ago

“…In this article, we deployed a quantitative approach to lithic analysis known as VRM (Lombao et al, 2020(Lombao et al, , 2021, which facilitates inter-assemblage comparability using geometric principles and is potentially applicable to any lithic assemblage regardless of context and techno-typological affiliation. Given the qualitative nature of conventional techno-typological analysis, we argue in this study for a quantitative approach to interpret lithic assemblages (Diez-Martín et al, 2010;de la Torre et al, 2021).…”

“…Previous studies relied on technological indices from variables like the number of removals on a core, cortex remaining, or average platform angles, among other proxies of reduction intensity (Clarkson, 2013;Douglass et al, 2018). We opted for the Volumetric Reconstruction Method (VRM) (Lombao et al, 2020(Lombao et al, , 2021, grounded in geometrical formulae specific to quartzite-based assemblages and the three-dimensional shapes under scrutiny. The VRM is specifically designed to examine Oldowan technology, addressing common problems such as the overlapping effect of stone reduction processes (Lombao et al, 2019), while allowing for comparisons among multiple knapping methods.…”

“…Statistical analyses of VRM data were processed with R (R Core Team, 2013). For full details on the VRM method, we refer the reader to its original source (Lombao et al, 2020), summarizing here the application procedure:…”

The technological behaviours of Homo antecessor: core management and reduction intensity at Gran Dolina-TD6.2 (Atapuerca, Spain)

“…Due to the morphological characteristics of the Cretaceous chert nodules as well as the quartzite, sandstone and quartz cobbles, with ellipsoid-like original shapes, we applied the Volumetric Reconstruction Method (VRM) (Lombao et al, 2020) to estimate the original size of the blanks and the core reduction intensity. The Neogene chert is found as large blocks with a great deal of morphological diversity (Ollé et al, 2013), so it was not included in the VRM analysis.…”