Microscope agnosticism and the characterization of sedimentary abrasion of flint stone tools

Abstract

The surface of lithic stone tools from Paleolithic archaeological sites can undergo a range of different postdepositional alterations, including sedimentary erosion induced by water displacement or wind. The surface of flint artifacts can reflect these alterations as changes in texture. Microscopic analyses and grayscale images can be employed to obtain quantitative data to help determine the degree to which the surfaces of flint stone tools have been altered. However, surface quantitative values depend directly on the image capturing system of each microscope. This raises the question of whether the quantitative values are actually capturing the evolution of the surface, whether they are dependent on the type of microscope and its image capturing system, and whether the detection of the degree of abrasion might vary depending on the type of microscope. The present work sought to determine whether data extracted from images from two different microscopes point to the same trends in surface change due to postdepositional alterations. Surface photographs of a sample of 25 flakes were taken using a Dino-Lite Edge 3.0 AM73915MZT and a 3D Optical Profiler Sensofar S neox 090. These flakes represented three different stages of alteration (fresh, ten hours of experimentally-induced sedimentary erosion, and geological neocortex). Results from grayscale images indicate that, despite yielding different numeric ranges, the quantitative values of the images from both types of microscope reflect the same trends in surface change. The classification accuracy of the three stages of erosion did not vary between microscopes.