THE MIDDLE AND LATE PLEISTOCENE ALLUVIAL TERRACES WITH MIDDLE AND LATER STONE AGE OCCUPATIONS IN THE MODDER RIVER VALLEY, SOUTH AFRICA

Long-term palaeoenvironmental records are rare in the interior of southern African but such sequences can provide critical information on Middle and Late Pleistocene human activities and adaptations as well as faunal shifts in response to climate changes. These sedimentary records require careful analysis to understand the paleoenvironment fluctuations due to intrinsic bias incorporated in them by their mode of deposition and nature of preservation. Here we report on new analysis and dating of Middle Stone Age (MSA) and Later Stone Age (LSA) occupations at Erfkroon in the western Free State’s Modder River valley. Four terraces have been identified with the oldest terrace, dating to the Middle Pleistocene, containing fossilized faunal remains and occasional artifacts. Numerous MSA and LSA locales were excavated in a Late Pleistocene terrace that span the last 120k years. Faunal remains occur throughout the terrace deposits. Isolated Equus capensis, Megalotragus priscus and Damaliscus niro partially articulated skeletons were recovered in a lower unit of the Late Pleistocene terrace and possibly associated with a significant drought, while in an upper unit of the same terrace human processed remains of plains game, such as Connochaetes gnou, Megalotragus priscus, Equus capensis and Phacochoerus sp. are abundant. Stable isotope and phytolith results indicate widespread C₃ plant environments except for a brief period in the Late Pleistocene at the LGM when there is a marked shift to C₄ plant communities. These results provide new information on Late Pleistocene climatic fluctuations in the grassland biome, the dual nature of wetland and open plains Florisian faunal species, and modern human adaptations in the interior grasslveld.