A microstratigraphic reevaluation of the Florisbad spring site, Free State Province, South Africa: Formation processes and paleoenvironment

International audienceThe Florisbad spring site has produced a large collection of fossil bones dating to the Middle Pleistoceneand several assemblages ofMiddle Stone Age (MSA) artifacts. The species featured in thefaunal collection define the Florisian Land Mammal Age, characterized mainly by grazing ungulatesthat reflect an open grassland environment. EarlyMSA artifacts found within the basal layersrepresent the earliest evidence of human presence at Florisbad, followed by an intactMSA occupationhorizon characterized by stone tools and animal bones, in direct association and primarycontext. These fossils and artifacts were found embedded within sand and peat layers. Previousstudies investigated the genesis of such deposits using field descriptions and bulk sedimentologicalanalyses. However, sediments were never studied within their original context, thus leading todifficulties in determining the formation processes of the deposits. Using a multianalytical microgeoarchaeologicalapproach including sediment micromorphology, FTIR and XRD, we were ableto show that the site is characterized by alternating aeolian sand layers reworked by lacustrinewater during the wet phases of the Pleistocene, and peat layers formed in marshes during dryphases. The results confirm most of the previous paleoenvironmental reconstructions and providea refined stratigraphic sequence of the site