Afromontane foragers of the Late Pleistocene: Site formation, chronology and occupational pulsing at Melikane Rockshelter, Lesotho

This paper provides a preliminary chronostratigraphic and palaeoenvironmental framework for the Late Pleistocene archaeological sequence at Melikane Rockshelter in mountainous eastern Lesotho. Renewed excavations at Melikane form part of a larger project investigating marginal landscape use by Late Pleistocene foragers in southern Africa. Geoarchaeological work undertaken at the site supports in-field observations that Melikane experienced regular, often intensive, input of groundwater via fissures in the shelter's rear wall. This strong hydrogeological connection resulted in episodic disturbances of the sedimentary sequence, exacerbated by other processes such as bioturbation. Despite this taphonomic complexity, a robust chronology for Melikane has been developed, based on tightly cross-correlated accelerator mass spectrometry (AMS) 14C with acid-base-wet oxidation stepped-combustion (ABOx-SC) pretreatment and single-grain optically stimulated luminescence (OSL) dating. The results show that human occupation of Melikane was strongly pulsed, with episodes of Late Pleistocene occupation at ∼80, ∼60, ∼50, ∼46–38 and ∼24 ka. At least three additional occupational pulses occurred in the Holocene at ∼9 ka, ∼3 ka and in the second millennium AD, but these are dealt with only briefly in this paper. Implications of the Late Pleistocene pulsing for the colonisation of high elevations by early modern humans in Africa ahead of dispersals into challenging landscapes beyond the continent are discussed.