Browsing by Author "Snoeck, Christophe"

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    Black pitch, carved histories: radiocarbon dating, wood species identification and strontium isotope analysis of prehistoric wood carvings from Trinidad's Pitch Lake
    (Elsevier, 2017-11-06) Ostapkowicz, Joanna; Brock, Fiona; Widenhoeft, Alex C.; Snoeck, Christophe; Pouncett, John; Baksh-Comeau, Yasmin; Schulting, Rick J.; Claeys, Philippe; Mattielli, Nadine; Richards, Mike; Boomert, Arie
    We report on the results of a multi-disciplinary project (including wood identification, radiocarbon dating and strontium isotope analysis) focused on a collection of pre-Columbian wooden carvings and human remains from Pitch Lake, Trinidad. While the lake's unusual conditions are conducive to the survival of organic artefacts, they also present particular challenges for analysis. There is a loss of any contextual association beyond that of the lake, and specific methodologies are required to deal with pitch contamination. A surprising taxonomic range of woods was employed for the various utilitarian and ceremonial items recovered. The 14C results range from ca. 3200 BCE to ca. 700 CE, and include the earliest known wooden carvings in the entire Caribbean. The strontium isotope results - interpreted with the aid of an isoscape developed for the project, based on extensive samples of modern trees across Trinidad and Tobago - indicate that most carvings are consistent with the site's immediate environs; however, a ‘weaving tool’ came from a more radiogenic region that is unlikely to be found on Trinidad, suggesting links with the South American mainland.
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    East-central Florida pre-Columbian wood sculpture: Radiocarbon dating, wood identification and strontium isotope studies
    (Elsevier, 2017-05-13) Ostapkowicz, Joanna; Schulting, Rick J.; Wheeler, Ryan; Newsome, Lee; Brock, Fiona; Bull, Ian; Snoeck, Christophe
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    Six centuries of adaptation to a challenging island environment: AMS 14C dating and stable isotopic analysis of pre-Columbian human remains from the Bahamian archipelago reveal dietary trends
    (Elsevier, 2021-01-29) Schulting, Rick J.; Snoeck, Christophe; Pouncett, John; Brock, Fiona; Bronk Ramsay, Christopher; Higham, Thomas; Devièse, Thibaut; Delancy, Kelly; Pateman, Michael; Keegan, William; Ostapkowicz, Joanna
    The limestone islands of the Bahamian archipelago provide a challenging environment for human settlement, one that was not taken up until after AD 700. The analysis of human skeletal remains offers new insights into how this challenge was met. A substantial program of AMS 14C dating on pre-Columbian humans (n = 66) provides a robust chronological framework for the period ca. AD 1000–1600, with the latter date suggesting the possible persistence of an indigenous Lucayan presence on the islands for some decades later than previously thought. Associated stable carbon (δ13C) and nitrogen (δ15N) isotope analyses imply an early focus on near-shore marine resources that seems to have rapidly led to their local over-exploitation, resulting in a shift towards horticulture based mainly on root crops. The Medieval Warm Period is very likely to have been a factor in the initial settlement of the islands; the impact of the Little Ice Age is less clear, with no marked changes in either δ13C or δ15N. Strontium isotope results are consistent with an origin of most individuals within the archipelago, with a limited (but potentially important for maintaining connections) presence of incomers from the Greater Antilles, and perhaps even further afield. Despite the relatively short history of pre-Columbian occupation, Lucayan adaptations to the Bahamian archipelago were dynamic and demonstrate resilience in the face of both human resource depletion and climate change.
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    Testing the effectiveness of protocols for removal of common conservation treatments for radiocarbon dating
    (University of Arizona / Cambridge University Press, 2017-08-09) Brock, Fiona; Dee, Michael; Hughes, Andrew; Snoeck, Christophe; Staff, Richard; Ramsey, Christopher B.
    To achieve a reliable radiocarbon date for an object, any contamination that may be of a different age must be removed prior to dating. Samples that have been conserved with treatments such as adhesives, varnishes or consolidants can pose a particular challenge to radiocarbon dating. At the Oxford Radiocarbon Accelerator Unit (ORAU), common examples of such substances encountered include shellac, the acrylic polymers Paraloid B-67 and B-72, and vinyl acetate-derived polymers (e.g. ‘PVA’). Here, a non-carbon containing absorbent substrate called Chromosorb® was deliberately contaminated with a range of varieties or brands of these conservation treatments, as well as two cellulose nitrate lacquers. A selection of chemical pretreatments was tested for their efficiency at removing them. While the varieties of shellac and Paraloid tested were completely removed with some treatments (water/methanol and acetone/methanol/chloroform sequential washes, respectively), no method was found that was capable of completely removing any of the vinyl acetate-derived materials or the cellulose nitrate lacquers. While Chromosorb is not an exact analogue of archaeological wood or bone, for example, this study suggests that it may be possible to remove aged shellac and Paraloid from archaeological specimens with standard organic-solvent-acid-base-acid pretreatments, but it may be significantly more difficult to remove vinyl acetate-derived polymers and cellulose nitrate lacquers sufficiently to provide reliable radiocarbon dates. The four categories of conservation treatment studied demonstrate characteristic FTIR spectra, while highlighting subtle chemical and molecular differences between different varieties of shellac, Paraloid and cellulose nitrate lacquers, and significant differences between the vinyl acetate derivatives.
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    Testing various pre-treatments on artificially waterlogged and pitch-contaminated wood for strontium isotope analyses
    (Frontiers, 2021-01-12) Snoeck, Christophe; Schulting, Rick J.; Brock, Fiona; Rodler, Alexandra S.; van Ham-Meert, Alicia; Mattielli, Nadine; Ostapkowicz, Joanna
    Strontium isotope ratios (87Sr/86Sr) are commonly used in archeological and forensic studies to assess if humans and fauna are local to the place they were found or not. This approach is largely unexplored for wooden artifacts recovered in archeological contexts, as wood – in the rare instances it does survive – is often poorly preserved. One of the most common ways wood is preserved is through the anoxic conditions found in waterlogged contexts. A more unusual form of preservation is through submergence in natural pitch. These depositional media contribute their own strontium values to the in vivo 87Sr/86Sr wood values, which needs to be removed prior to analysis. Here we test several pre-treatment methods to remove potential strontium contamination from wood samples that were artificially immersed in seawater and pitch from Trinidad’s Pitch Lake. Water rinses and acid-leaching tests were carried out with hydrochloric acid and acetic acid to remove exogenous strontium from experimentally waterlogged wood. These tests removed large amounts of strontium from the samples and did not enable the recovery of the endogenous 87Sr/86Sr signal. For samples artificially immersed in pitch, the pre-treatments tested were based on radiocarbon dating procedures and carried out with and without the aqueous-based acid-base-acid (ABA) step. The use of organic solvents alone (methanol and toluene) removed exogenous strontium originating from the pitch. However, the ABA step eliminates large amounts of in vivo strontium from the samples. These tests show that 87Sr/86Sr values of wood are altered by the presence of pitch and water. With adequate pre-treatment using exclusively organic solvents, it may be possible to remove this contamination for samples immersed in pitch. However, the aqueous-based ABA pre-treatment should be avoided. The removal of contamination from waterlogged samples was unsuccessful with the current pre-treatment protocols and more research is needed. More importantly, and unexpectedly, 87Sr/86Sr values may extend outside of the mixing line between the wood’s endogenous strontium and the water. These results indicate the need for extreme caution when attempting to determine the provenance of waterlogged wood.
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    ‘The darker angels of our nature’: Early Bronze Age butchered human remains from Charterhouse Warren, Somerset, UK
    (Cambridge University Press, 2025-02) Schulting, Rick J.; Fernández-Crespo, Teresa; Ordoño, Javier; Brock, Fiona; Kellow, Ashleigh; Snoeck, Christophe; Cartwright, Ian R.; Walker, David; Loe, Louise; Audsley, Tony
    Direct physical evidence for violent interpersonal conflict is seen only sporadically in the archaeological record for prehistoric Britain. Human remains from Charterhouse Warren, south-west England, therefore present a unique opportunity for the study of mass violence in the Early Bronze Age. At least 37 men, women and children were killed and butchered, their disarticulated remains thrown into a 15m-deep natural shaft in what is, most plausibly, interpreted as a single event. The authors examine the physical remains and debate the societal tensions that could motivate a level and scale of violence that is unprecedented in British prehistory.