Stable isotope evidence of late MIS 3 to middle Holocene palaeoenvironments from Sehonghong Rockshelter, eastern Lesotho

Abstract

ABSTRACTEvidence for human occupation of southern Africa's high‐altitude Maloti–Drakensberg Mountains is surprisingly common in the last glacial, yet the attraction of this relatively severe, cold region for hunter‐foragers remains unclear. Sehonghong Rockshelter (1870 m asl), in the eastern Lesotho Highlands, provides evidence for human occupation spanning Marine Isotope Stage 3 through the late Holocene. Excellent organic preservation provides opportunities for establishing multiple palaeoenvironmental proxy records to address this conundrum. In high‐altitude zones, the proportions of C3 and C4 plants archived in soil organic matter and faunal enamel provide sensitive indicators of past temperature shifts. We first extended the radiocarbon chronology to ca. 35 ka using ABOx‐SC radiocarbon dates of charcoals. Next we analysed stable isotopes in soil organic matter from the sedimentary sequence, and in faunal tooth enamel from the newly dated lower strata. The results suggest, predictably, that C3 vegetation and low temperatures prevailed until early warming at ca. 15 ka, with a series of sharp shifts thereafter. Low values for δ13C and δ18O in faunal enamel ca. 33 ka suggest a negative temperature excursion at this time, and potentially greater precipitation as snowfall in the highlands compared with lower altitudes.