Differentiation of thermal activities by FTIR – Analyses of sandstone slabs from the late Mesolithic and early Neolithic site of Neustadt LA 156 (Northern Germany)

Abstract

FTIR analyses were tested as reliable for the fast identification of heated sandstones from archaeological contexts and the differentiation of thermal activities. FTIR spectra of experimentally heated sandstone samples reveal distinctive peak changes depending on heating intensity. The method was applied to stone slabs from the late Mesolithic/ early Neolithic site of Neustadt LA 156 (Northern Germany), in order to reconstruct their individual functions in relation to fire and with this, hearth activities and hearth constructions. FTIR analyses prove different heat exposures of the individual stones that point to diverse functions in relation to fire and partly contradict assumptions from visual inspection. Most stones have been slightly to moderately heated, often from one side only, potentially taking advantage of the good heat capacity of sandstone. This case study for the identification of heated sandstones from archaeological contexts builds a basis for reconstructions of fire use, hearth constructions and thermal energy management in the late Mesolithic and early Neolithic, which played an important role in the intensified land use systems.