The geomorphology and aeolian deposits in the vicinity of Florisbad

[摘要] The discovery of the Florisbad hominid prompted further archaeological andpalaeoanthropological research in the Florisbad area. However, research that looksspecifically at the geomorphology and aeolian deposits around Florisbad has beenvery limited, although aeolian processes and sand dunes have been widelyrecognized as being of significance in understanding past environmental conditionsin this area. Geologists have also shown an interest in trying to explain the formationof the Florisbad spring and fossil site. The Florisbad spring site has a complex stratigraphy because the deposits arelithologically variable due to the fact that they are the product of an unusualdepositional environment. Many hypotheses have being proposed in trying tounderstand the complex depositional environment at Florisbad. This researchsuggests that, in order to better understand the complex depositional environment ofFlorisbad, there is a need to understand the surrounding geomorphological setting interms of geohydrological and geomorphic processes and features. The methodology comprises a review of current literature on lunette dunes, andprevious work undertaken on the geomorphology and geology at and aroundFlorisbad, an examination of aerial photographs to identify lunette dunes in thevicinity of Florisbad, and fieldwork to ground-truth the dunes. Field sampling,laboratory work (sedimentological techniques, pH, conductivity and geochemicalanalysis) as well as statistical analyses (principal component and cluster analyses)were employed to compare the characteristics of the lunette dune sediments withthose at the spring site itself, and to assist in a general palaeoenviromentalreconstruction.The results of the laboratory analyses do not reveal any obvious differences withrespect to sediment particle size and pH, between the lunette dunes and the springsite. However it was noted that there were minor differences when it came to dunestructures, electrical conductivity and chemical composition. There is convincingevidence that the sediments are primarily wind-blown in origin. The geochemicalresults suggest the lunettes are older than the dune at the spring site. Two opticallystimulated luminescence dates were determined for a lunette dune close toFlorisbad. The samples were dated to 500 years, and it is suggested that this isbecause of reworking of sediments down the slope. The overall geomorphology, as described in this study, suggests a shallowdepression (Florisbad-Soutpan) in which both fluvial and aeolian processes haveconspired to create a unique landscape which has promoted the formation andpreservation of dune deposits and the unique archaeological site which is Florisbad.

[发布机构] University of the Free State