Stone Tool Analysis: Scar sequencing
The process of stone toolmaking is a subtractive process where pieces of stone are progressively removed from the starting piece to achieve the final result. A stone tool preserves remnants of the very last flakes removed, which intrude into older flake scars, and those into still-older flake scars, and so on. The sequence of flake removal is recorded in the way the scars intrude into each other.
Some lithic analysts are specially trained to determine the ordering of the scars on a tool, and by reconstructing the scars chronologically—and comparing this to the waste flakes found in association—the analyst can reconstruct in some detail the various steps that were taken to manufacture the tool.
These steps are referred to as the ‘reduction sequence’ or ‘châine opératoire’ for the particular technology. This is called ‘diacritical analysis’ and involves closely studying the chronological ordering of the scars by assessing tiny clues on the edges of flake scars.
Run ons
Run-on ‘tongues’ often project a short distance up ridges and high points and then terminate in steps, hinges, or feathers, and these small details can be seen under magnification. These tongue-like projections are intact on the later scar, and removed from the earlier scar. By carefully mapping out the direction of overlap indicated by run-ons, a sequence of scar removals can be reconstructed for the artefact. This sort of diacritical analysis is most suitable for fine-grained stones where run-ons are clearly expressed.
