Experimental study of the charcoal taphonomy of Pistacia lentiscus (Mastic tree)

Abstract

Wood charcoal is one of the most abundant botanicals which are uncovered during excavations globally. Their potential research value is wide, with a number of ways they can be studied. One such avenue of study is charcoal taphonomy, which seeks to understand how different phases of the chaîne opératoire of fuel and fire management alter the charcoal in ways which can be used to interpret back those steps. At the site of Latnija in Malta, the charcoal record is dominated by the Mediterranean shrub, Pistacia lentiscus, with profuse signs of taphonomic markers related to combustion and postdepositional processes. This thesis seeks to reconstruct the firing conditions which produce these markers, through the experimental burning of Pistacia lentiscus under conditions typical of Mesolithic hearths. This includes controlling for calibre, wood state, position in wood anatomy, firing temperature, firing atmosphere, cooling method, and number of firings. In total 300 controlled laboratory samples, 217 uncontrolled outdoor fired samples, and 10 archaeological samples were processed for this study. Laboratory samples were processed in groups of five, testing sixty different combinations of variables. Samples were photographed under a HIROX in their transverse section, and their alterations were classified, measured by height and area, and calculated for the number of cracks and percentage of area cracked in samples. The data generated did find meaningful ways to detect differences in firing temperature, firing atmosphere, cooling method, and relative position in wood anatomy. It showed further promise that discriminating between certain states and calibres may also be possible, but requires more testing. These differences proved true not just for laboratory samples, but also when applied to the uncontrolled and archaeological samples, showing utility for archaeological application.