Heritage Cases

Export of Materials for Dating and Paleoclimate Analysis from Wonderwerk Cave




Case Type: 


Request to export microfauna, fauna, sediment samples, and speleothems from Wonderwerk Cave for dating (OSL, Paleomagnetic, Uranium/Thorium, and Uranium/Lead) and faunal analysis (fauna, microfauna). No artifacts are included in this export request. All materials are from Excavation 1, Wonderwerk Cave, Northern Cape Province.


Excavation 1 at Wonderwerk Cave preserves a unique sequence spanning the entire Earlier Stone Age. Developing a robust absolute chronology for this sequence will provide an essential timescale for the region. Research on faunal materials provides an opportunity to develop insight into the ecological context of human evolution. The following samples are requested for export: 1. Paleomagnetic samples (150 samples). These are 1 x 1 cm. cubes collected in quartz boxes. The provenience of each sample is recorded photographically and in the GIS database for the site. All samples will be analyzed by Dr. Ron Shaar at the Institute of Earth Sciences at the Hebrew University. Samples will be maintained in the reference collection in Dr. Shaar's lab and will be made available to other researchers upon request. 2. Optically stimulated luminescence: Optically stimulated luminescence offers a method of dating sediments and is usually applied to contexts younger than 500,000 years ago. Dr. Marine Frouin, Oxford University, is developing a new luminescence technique, called radiofluorescence, to date K-feldspar grains contained in sediments or tuffs. In laboratory, the limit of the technique reaches ~3 Ma (maybe aven 4 Ma), but it has never been tested on archaeological/geological context of this time period. If it works on real samples, of course, it would be possible to date any sites containing sediments where argon-argon and tephra correlation are not possible. I am attaching a recent publication describing the new protocol. Four samples were collected by Dr. Naomi Porat that will be used by Dr. Frouin to test this new method. Matching samples will be analyzed by Dr. Porat using standard protocols. 3. Uranium/Thorium-- U-series dating of ostrich eggshells (OES) using fs-LA-ICPMS techniques. When an egg forms, a small amount of Uranium (U) is incorporated in the calcitic eggshell structures. Conversely, Thorium (Th) is not metabolized and the sheel is then free of it. Because of this desiquilibrium between U and Th, eggshells are materials potentially datable with the U/Th method. The classic approach consists in dissolving with acids a fragment of a shell and measure the U and Th isotopic ratios. However, doing that makes difficult to quantify extra radioisotopes which may have been incorporated in the shell during its burial (because of post-depositionnal processes) and may lead to biased U-series ages. The alternative approach we are developping consists in analysing the shell without making any chemical pre-treatment and measure directly the U and Th isotopic ratios on polished sections perpendicular to the egg surface. Femto-second (fs) laser-ablation (LA) techniques coupled to high-sensitive ICP-MS allow performing this kind of analyses with a high spatial resolution (typically 30 ┬Ám) : a map of the U and Th isotopes can then be acquired, allowing the identification of areas not affected by post-depositionnal processes or diagenesis. Uranium-Thorium will be carried out by Norbert Mercier and Chantal Tribolo at the University of Bordeaux Montaigne. Six samples will be exported for this analysis. Following analysis all samples will be returned to the McGregor Museum. 4. Uranium/Lead-- Uranium/Lead dating is effective in dating the age of formation of speleothems. Preliminary research by Robin Pickering demonstrates that this method works at Wonderwerk. Following up on Pickerings results the goal is to analyse a robust sample from well provenienced samples from the new excavations at Wonderwerk. Twenty six samples will be exported to the University of Toronto, Department of Earth Science, Jack Slatterly lab. Following analysis all samples will be returned to the McGregor Museum for permanent curation. 5. Fauna-- Seventeen samples of unidentified bone fragments (total number of fragments 165) will be analysed as an exploratory project aiming to screen faunal assemblages for potential human remains. It is a collaboration between several institutions, the Crick Institute and Oxford in the UK and the Max Planck Institute for the History of Human Science. The first step will be to establish whether there is collagen and aDNA preservation at any of the bones in Wonderwerk using %N and ZooMS, at least for collagen preservation. Only need 20-50mg of bone is required, so the analysis is minimally destructive. Analysis will be carried out at Oxford by Katerina Douka. Following analysis all bones will be returned to the McGregor Museum for curation. 6. Microfauna-- Eight samples of microfauna from from square K488 from the new excavations. This is a 0.25 sq. meter unit at the eastern end of the south profile of excavation 1. It is from units equivalent to Peter's St. 6/7. There are three stratigraphic units represented in this sample that are in order from top to bottom SR/MM/TS. MM is particularly rich in microfauna. This sample will be sent to Dr. Yolanda Fernandez Jalvo (National Museum of Natural Sciences, Madrid) for taphonomic analysis following protocols described in Ferenandez Jalvo and Avery 2015. Following taphonomic analysis the sample will be sent to Dr. Margaret Avery (IZIKO) for taxonomic analysis and then returned to the McGregor Museum for curation.


Thursday, September 13, 2018 - 20:13






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