Fire history reconstruction from Black Carbon analysis in Holocene cave sediments at Ifri Oudadane, Northeastern Morocco

Abstract

Fire residues elucidate the where, when, and how of land use. Charcoal analysis provides insights into wood-burning practices, but is restricted by the size of identifiable particles. The present paper is the first to apply a black carbon (BC) method to archaeological sediment deposits. This method oxidizes charcoal and soot particles from the bulk sediment to benzene polycarboxylic acids (BPCAs), independent of size. Our aim was to test the potential of BC analysis in order to elucidate the input from grass and wood fires and discuss the potential limitations of the method on sediments of the Ifri Oudadane rock shelter, Morocco. Sediments cover the cultural transition from hunter–gatherers to food-producing communities (Epipaleolithic to Neolithic period, 11–6 kyr cal. BP), which has previously been shown to affect the geochemical, palynological, and archaeological inventories of these sediments. We found respective changes in BC; specifically, content was highest during the Epipaleolithic, with an average of 35% BC in organic carbon (Corg) compared with Neolithic sediments with an average of 24% BC in Corg. The fire temperature (expressed by BPCA composition) changed significantly, which suggests that wood fires dominated in the Epipaleolithic and grass fires dominated in the Neolithic period. These findings agree with a previously suggested shift in usage. We are able to show here that BC analysis, when combined with other proxy data and archaeological findings, can contribute to a deepened understanding of past human activities.