The Organization of Chipped-Stone Economies at Piedras Negras ...

These larger pieces of production debitage do not seem to have been thrown in typical
trash dumps, but rather reserved for obsidian eccentric production.
One face of the core was reduced by pressure, and then further percussion blades
were removed from the sides of the core that were not initially regularized (Figures 6.3
and 6.9). These blades and flakes feature dorsal surfaces, which have pressure scars and
older, heavily worn, percussion scars. All of these debitage types are evident in the
obsidian eccentrics found at Piedras Negras. The result of this reduction technique was
exhausted cores with an oval or lenticular cross section, with one side reduced by
pressure, and the other retaining its original percussion scars--probably remnants from the
original manufacture at the source (Figure 6.8).
Another marker for the reduction of a blade core on one or more sides is the
earliest pressure blades and flakes removed from the core (Figures 6.10 and 6.11). These
blades are termed first- and second-series blades (1s and 2s blades) by Clark and Bryant
(1997). According to Clark, first-series blades are the first pressure blades removed from
the core and can feature both pressure and percussion scars on their dorsal surfaces, but
the percussion scars are found along the entire length of the blade. Second-series blades
and flakes tend to have pressure scars on the proximal end of the flake or blade and
percussion scars on the distal end (Figure 6.11). It should be noted that first- and second-
series flakes and blades do not necessarily mark early stages of reduction of a core on one
or more sides, because reduction extending into the sides or edges of the working face of
the core (i.e., facets still featuring percussion scars) happens throughout the use-life of the
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