Doctor of Philosophy
School of Earth, Atmospheric and Life Sciences
This thesis aims to contribute to the determination of prehistoric stone tool function from traces of use for reconstructing and understanding hominin prehistoric behaviour. While macro-morphological approach provides important information about the context of tool use, it does not provide secure evidence of how the tool was actually used or what materials were processed. Retouched tools that do not match formal types, and unretouched flake tools are potentially even more problematic for morphological based interpretations of function.
Microscopic use-wear analysis is an essential technique to determine use of stone tools, but it needs to be complemented by residue analysis for more robust functional interpretations. Conventional use-wear analysis identifies residues in the first stages of optical microscopy, followed by targeted analysis of residues, which often need to be removed. However, optical recognition of in situ, amorphous micro-residues is difficult. Additionally, stone artefacts not preselected for macro-residues may have low levels of preservation, and in that case cannot always benefit from pre use-wear analysis.
Raman microscopy offers an alternative initial approach to residue analysis because it is a fast, non-destructive analytical technique, with high spatial resolution and it can rapidly identify a wide range of organic and mineral residues (bone, lipids, proteins, cellulose, lignin, starch and iron oxides).
This thesis develops a new methodology, to enhance the use of spectroscopic technique in discriminating use-related residues from contaminants, and to provide interpretations both independent of, and complementary to, conventional use-wear analysis. Indeed, microresidues on prehistoric stone tools can arise from diverse origins that may be incidental to tool-use, naturally occurring in sediment, and arising from post-depositional processes and from other sources including ancient and modern contamination. To learn about hominin behaviour from stone tools, it is critical to filter the possibilities and retain only use-related materials. Consequently, Raman microscopy is positioned as a potential first step, but needs to develop its own micro-residue discrimination strategy. A whole set of criteria and complementary observations are needed, including correlation between use-wear and microresidues distributions, which require systematic spatial localisation and secure identification. Initial Raman microscopy is bringing a new approach and has the advantages of being complementary to and independent of conventional use-wear residue analysis. Additionally, to interpret stone artefacts micro-residues Raman analysis, this work developed a reference material database that is critical to compare with analysed residues on prehistoric stone tools. Raman references for different chemical compounds, modern and natural materials have been developed here, as well as targeted stone tools experiment to investigate type of microresidues deposited.
This thesis has been also planned from the beginning to be part of the “Out of Asia” ARC Laureate Project, which was designed to improve understanding of the timing and dispersal of prehistoric hominin populations into South Asia and Australia. In this project, archaeochemistry, including different types of spectroscopic methods (Infrared, Raman, GCMS), was planned to contribute to understanding hominin behaviour by analysing stone artefacts recovered from selected archaeological sites and to determine their function. Consequently, two available prehistoric stone artefacts collections were selected, from Liang Bua and Denisova cave, to apply the developed methodology in Raman spectroscopy for reconstructing and understanding hominin prehistoric behaviour.
Analysis results of different sets of artefacts collected from these two prehistoric sites allow to observe continuity or variation of stone tools use and behaviour through time, which requires comparisons of worked materials and particular ways of using stone tools recovered from different archaeological layers.
This thesis shows that Raman spectroscopy applied to prehistoric stone tools is a successful analysing method and can be considered as a technique with a potential pivotal role in relating use-wear and other complementary techniques like GS-MS. Indeed, as Raman spectroscopy is a non destructive technique and leaves intact micro-residues on stone surfaces, any tagged concentrated spot of micro-residues (e.g., lipids) could be targeted in a second step of analysis with application of any complementary techniques on material having being securely linked to prehistoric use on stone artefacts. In that perspective, this thesis can open a way forward to optimise information from lithic functional analysis by combining, and ensuring that, the different analysing methods (use-wear analysis, spectroscopic analysis, GC-MS separative methods) will better complement each other in the future.
Bordes, Luc, Analysing micro-residues on prehistoric stone tools by Raman microscopy and determining their origins, Doctor of Philosophy thesis, School of Earth, Atmospheric and Life Sciences, University of Wollongong, 2019. https://ro.uow.edu.au/theses1/640
Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.