AbstractsGeography &GIS

The Cradle of Humankind is a 47 000 hectare demarcated area with over three dozen fossil-bearing cave sites well known for the preservation of fossil evidence of early hominin taxa such as Australopithecus Africanus, Australopithecus Sediba, Paranthropus Robustus and Early Homo. As a result, a database of precise and accurate chronological data for fossil-bearing cave deposits of the Cradle of Humankind (similar to that for East African fossil sites) is very important, but developing one has proven extremely challenging. The main challenge is that the fossil-bearing deposits at the cradle are mainly complex breccias with a chaotic, localized stratigraphy and no association to any volcanic ash beds, unlike the East African deposits which are lacustrine and fluviatile deposits interbedded with volcanic ash layers. However, substantial success has been obtained recently through the combination of U-Pb dating of CaCO₃ speleothems and palaeomagnetic dating (magnetostratigraphy) after many attempts and unconvincing results from techniques such as biostratigraphic correlations, electron spin resonance on teeth and cosmogenic burial dating of the sediments. The problem with U-Pb dating of CaCO₃ speleothems is that this requires samples that are extremely clean (i.e. detrital-free) and have an appreciable U content (close to 1 ppm), and such material is at many sites not available...