Stone Tool Analysis: Scar sequencing

Tenerean disk re-do

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 attributes are found on the edges of flake scars.  As the crack propagates through the stone, the crack’s edges follow the contours of the previous flake scars.  The fracture front moves in a series of tiny ‘run-ons’ that follow up the various minute ridges and high points on the core face.  These run-ons can provide the analyst with clues for determining the sequence of flake removals.

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Clovis Point

Scar Stratigraphy

The law of superposition, first formulated by the Danish scientist Niels Steensen in 1669, states that the oldest material in an archaeological deposit lie at the bottom, and they become progressively younger as you approach the top.  We refer to a layer of deposits as ‘stratified’ and record the specifics of a stratified archaeological sequence with a Harris matrix.  The overlapping flakes scars on a stone tool are also stratified, but since the process of flaking progressively removes material rather than adding to it, the stratigraphy is reversed: the highest flake scar is the oldest, and the lowest flake scar is the youngest.  

Tenerean disk re-do

Tenerean Disk