Stone Tool Analysis: 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.
On some complex stone tools, remnants of earlier reduction stages are preserved as islands cut away on one or more sides by more recent flake scars. This provides further clues to the lithic analyst for reconstructing the manufacturing steps involved in making the artefact.