Depositional environments of the Florisbad Spring site and surrounds: a revised synthesis

Abstract

The Florisbad Spring site displays lithological and stratigraphical complexity within a unique geomorphological setting. Various hypotheses have been proposed to explain this complex depositional environment, and the origins of the spring site and mound are an ongoing topic of debate. To provide a context within which better to understand the depositional environment of Florisbad, the site and its surroundings were investigated. To this end, aerial photographs and Google Earth imagery, combined with field mapping and an analysis of sediments from and around the spring mound, were used to assist in a broad palaeoenvironmental reconstruction. Particular attention was paid to the depositional environment on and around the spring mound. The results did not reveal obvious differences with respect to the sedimentology of lunette dunes in the vicinity, and the spring mound itself. However, there were minor, but potentially significant differences in structure and chemical composition. Evidence suggests that the sediments are primarily of aeolian origin, while geochemical differences suggest that the south-western lunette could predate the spring mound. Optically stimulated luminescence ages confirm reworking of sediment for one of the lunettes. The morphology of the lunettes suggests that this technique would not necessarily yield primary ages for lunette formation due to sediment reworking. The meso-scale geomorphology suggests a shallow depression in which structural control and both fluvial and aeolian processes have worked together to create a unique landscape that promoted the formation and preservation of dune deposits and the unique archaeological site that is Florisbad.