Freezing in-sight: the effect of frost cycles on use-wear and residues on flint tools

Alterations caused by post-depositional processes have long hampered functional analysis of stone tools, and several attempts have been made to understand their effect on the visibility and identification of use-related traces and residues. Alterations can be caused by a broad range of phenomena that involve both mechanical and chemical processes. In this article, we present the results of an experimental study focused on the reproduction of alterations caused by repeated freeze–thaw cycles, which are among the crucial processes that many prehistoric artefacts have been subjected to after their deposition. Thanks to the use of a climate chamber, we succeeded in reproducing alteration polish comparable to what is frequently observed on prehistoric stone tools, in particular those dating to the Palaeolithic and Mesolithic periods. The results open new possibilities for exploring the effect of post-depositional processes on the preservation of use traces and residues and demonstrate that alterations can also contribute to the understanding of site formation processes.