Characterization and dating of San rock art in the Metolong catchment, Lesotho: A preliminary investigation of technological and stylistic changes

Recent research on Later Stone Age (LSA) San rock art in southern Africa has unveiled some of the paint recipes the artists employed. However, these discoveries still need to be linked to human activities in or near the rock shelters where the paintings were made. In this paper, we report characterization and dating results from the catchment of the Metolong Dam, Phuthiatsana Valley, Lesotho. A total of 92 rock painting samples, six grindstones with traces of colouring materials from an excavated context, and 17 potential raw colouring materials were studied. We identified three previously unreported ingredients used by the artists: manganese oxides, calcined bones, and soot. Grindstones are stained with the same raw materials that the painters used. We propose that one of them may have served to prepare the red pigment used to make a human figure and a bichrome eland at Ha Makotoko, but direct links remain difficult to establish with certainty. The potential colouring materials in the valley are red clays, white clays (kaolinite and illite-or-montmorillonite), and gypsum, three compounds used as paints by the artists. Tests conducted to verify their suitability for paintings show these materials may have been ground, but settling (after pre-grinding) offers a quicker and easier way to obtain a fine powder as observed in the paints. Finally, 12 AMS dates provide an initial framework for studying the changing use of paint recipes in the Phuthiatsana Valley over time. Charcoal appears to have been employed over a period of at least 3000 years and carbon black for at least 2000 years, with soot seemingly used only before 2000 cal. BP. This study is currently the largest characterization and dating study of LSA rock art in southern Africa and shows the potential that such combined investigations offer for linking excavated and parietal components of the region's hunter-gatherer archaeological record.