Revisiting lithic edge characterization with microCT: multiscale study of edge curvature, re-entrant features, and profile geometry on Olduvai Gorge quartzite flakes

The angle and shape of lithic tool edges have long been used as a method of inferring prehistoric tool function. However, accurately measuring and characterizing edge angles of lithic tools is notoriously difficult. Studies using goniometers, calipers, or morphometrics often rely on two-dimensional...

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Bibliographic Details
Published in:Archaeological and anthropological sciences 2022-02, Vol.14 (2), Article 33
Main Authors: Macdonald, Danielle A., Bartkowiak, Tomasz, Mendak, Michał, Stemp, W. James, Key, Alastair, de la Torre, Ignacio, Wieczorowski, Michał
Format: Article
Language:English
Subjects:
Angles
Anthropology
Archaeology
Chemistry/Food Science
Earth and Environmental Science
Earth Sciences
Geography
Geometry
Life Sciences
Lithic
Measurement
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Summary:The angle and shape of lithic tool edges have long been used as a method of inferring prehistoric tool function. However, accurately measuring and characterizing edge angles of lithic tools is notoriously difficult. Studies using goniometers, calipers, or morphometrics often rely on two-dimensional representations of edges. Furthermore, there have been limited attempts to quantitatively document stone tool edges based on surface metrology, most notably edge curvature. In this study, we use microCT to capture models of the complex geometry, or ‘freeform’ surfaces, of experimental quartzite flakes from Olduvai Gorge (Tanzania) to document and mathematically calculate edge curvature using multiscalar length-scale analysis. Through this analysis, we also explore the quantification of re-entrant (overhang) features on lithic edge cross-sections. On lithic tools, especially coarse-grained rocks with complex surface topographies, such as quartzite, traditional techniques for edge angle measurement are incapable of capturing re-entrant features on edge profiles. Here we present the first archaeological study that addresses the measurement of these re-entrant features, using novel length-scale and curvature analysis methods of calculating edge angles for complex freeform surfaces. With these new methods for measuring edge angles, we can consider the impact of complex geometry, including re-entrant features, on the function of lithic tools in the past.
ISSN:1866-9557
1866-9565
DOI:10.1007/s12520-022-01504-7