Ceramic studies using portable XRF: From experimental tempered ceramics to imports and imitations at Tell Mozan, Syria

Posted on December 27, 2017 by ARCAS

Publication date: February 2018Source:Journal of Archaeological Science, Volume 90 Author(s): Ellery FrahmStudies of Northern Mesopotamian complex societies have long been predicated on ceramic wares, whereby ceramic variation is thought to reflect cultural variation. There is, however, an increasing appreciation for the role of imitation, itinerancy, and other phenomena in the distribution of ceramic styles. Much of this newfound nuance is due to chemical studies. Increasingly ceramics have been studied using portable X-ray fluorescence (pXRF). The utility of pXRF in ceramic research relies on being able to interpret the data in behaviorally meaningful ways. Thus, one approach to considering the efficacy of pXRF for ceramic studies proceeds from understanding the ways in which clays and tempers act as variables and influence the data in ways that reflect past behaviors. First, this study uses experimental replicas to exert systematic control over individual parameters (e.g., temper size, volume), allowing a better understanding of their influence. Second, this study considers Bronze Age wares at Tell Mozan in northeastern Syria. The experimental ceramics and Tell Mozan sherds are technological products that retain chemical evidence of choices made during their production. In the experimental ceramic set, a predicted phenomenon (e.g., the “dilution” effect from temper) occurred as expected, and elemental data differentiated clays and tempers selected for their manufacture. In the archaeological assemblage, elemental approaches established that distinctions between imports and locally made imitations are not always apparent by conventional means, and the use of pXRF is one way to overcome current shortcomings as well as contribute new insights.

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‘Illuminating’ the interior of Kukulkan’s Pyramid, Chichén Itzá, Mexico, by means of a non-conventional ERT geophysical survey

Posted on December 26, 2017 by ARCAS

Publication date: February 2018Source:Journal of Archaeological Science, Volume 90 Author(s): Andrés Tejero-Andrade, Denisse L. Argote-Espino, Gerardo Cifuentes-Nava, Esteban Hernández-Quintero, René E. Chávez, Alejandro García-SerranoChichén Itzá, located in the north-central portion of the Yucatán Peninsula, is one of the major pre-Hispanic cities established in the southern lowlands of Mexico. The main objective of this investigation was to “unveil” the interior of the pyramid of El Castillo, also known as the Temple of Kukulkan, an emblematic structure in this archaeological site. To that end, 828 flat electrodes were deployed around each of the 9 bodies that compose the pyramid, including the base of the structure. A dataset consisting of 37,548 observations was obtained. A precise topographic control for each electrode was carried out and introduced in the inversion model. The mathematical process to compute a final 3D model was made possible by taking 9 observation levels (33,169 measurements) into account, due to computational limitations. The results showed the existence of two older pyramids within the main Mayan building and provided important information regarding our understanding of this Mayan civilization. Future archaeological studies in the older substructure could reveal information about early settlement on this site, its evolution in time and its cultural influences.

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Experimental design of the Cu-As-Sn ternary colour diagram

Posted on December 22, 2017 by ARCAS

Publication date: Available online 22 December 2017Source:Journal of Archaeological Science Author(s): M. Radivojević, J. Pendić, A. Srejić, M. Korać, C. Davey, A. Benzonelli, M. Martinón-Torres, N. Jovanović, Ž. KamberovićThe aesthetic appearance of metals has long been recognised in archaeometric studies as an important factor driving inventions and innovations in the evolution of metal production. Nevertheless, while studies of ancient gold metallurgy are well supported by modern research in colour characteristics of gold alloys, the colour properties of major prehistoric copper alloys, such as arsenical copper and tin bronzes, remain either largely understudied or not easily accessible to the western scholarship. A few published studies have already indicated that alloying and heat treatment change the colours of copper alloys, although they are mainly based on examples of prehistoric tin bronze objects and experimental casts. Here we present a procedure for building the Cu-As-Sn ternary colour diagram, starting with experimental casting of 64 binary and ternary alloys in this system. We used two types of information to produce two different ternary colour diagrams: one based on photographs of the samples, and the other based on the colorimetric measurements. Furthermore, we developed a procedure for creating a graphic representation of colours in the Cu-As-Sn ternary diagram using QGIS. As an initial case study, we plotted the composition of the world’s earliest tin bronze artefacts; the graphic representation further supports claims about the importance of a golden hue for their invention and demand, c. 6500 years ago. We argue that the presented colour diagrams will find wide use in future investigations of aesthetics of prehistoric copper alloys.

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Earliest salt working in the world: From excavation to microscopy at the prehistoric sites of Ţolici and Lunca (Romania)

Posted on December 20, 2017 by ARCAS

Publication date: January 2018Source:Journal of Archaeological Science, Volume 89 Author(s): Dominique Sordoillet, Olivier Weller, Nicolas Rouge, Martine Buatier, Jean-Pierre SizunSince the Early Neolithic, salt has played an important role in the social and economic development of populations. Consequently, the study and comprehension of salt management strategies have become a significant component of current archaeological research. This study is part of an interdisciplinary research program consisting of excavations and detailed analyses on two Early Neolithic salt working sites situated in the sub-Carpathian region of Romania, Lunca and Ţolici (county Neamţ). These remarkably well-preserved sites are characterised by stratified deposits several meters thick. Detailed stratigraphic descriptions were followed by optical microscopy analysis (soil micromorphology) and scanning electron microscopy (SEM) coupled with geochemical analysis (EDS). The aim of these analyses was to identify specific sedimentary, petrographic and chemical characteristics that could be linked to salt working process. The results enable us to describe the main site formation process over time and to detect chemical components of edible salt (Na and Cl) in Early Neolithic ashes. These new data consolidate previous interpretations of the operating procedures implemented from the Early Neolithic to the Bronze Age. Two techniques appear to have been preferentially adopted: pouring natural brine onto combustion structures during the Early Neolithic and evaporation in specific ceramic containers from the Chalcolithic onwards.

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Differentiating between cutting actions on bone using 3D geometric morphometrics and Bayesian analyses with implications to human evolution

Posted on December 7, 2017 by ARCAS

Publication date: Available online 6 December 2017Source:Journal of Archaeological Science Author(s): Erik Otárola-Castillo, Melissa G. Torquato, Hannah C. Hawkins, Emma James, Jacob A. Harris, Curtis W. Marean, Shannon P. McPherron, Jessica C. ThompsonStudies of bone surface modifications (BSMs) such as cut marks are crucial to our understanding of human and earlier hominin subsistence behavior. Over the last several decades, however, BSM identification has remained contentious, particularly in terms of identifying the earliest instances of hominin butchery; there has been a lack of consensus over how to identify or differentiate marks made by human and non-human actors and varying effectors. Most investigations have relied on morphology to identify butchery marks and their patterning. This includes cut marks, one of the most significant human marks. Attempts to discriminate cut marks from other types of marks have employed a variety of techniques, ranging from subjectively characterizing cut mark morphology using the naked eye, to using high-powered microscopy such as scanning electron microscopy (SEM) or micro-photogrammetry. More recent approaches use 3D datasets to obtain even more detailed information about mark attributes, and apply those to the fossil record. Although 3D datasets open promising new avenues for investigation, analyses of these datasets have not yet taken advantage of the full 3D surface morphology of BSM. Rather, selected cross-sectional slices of 3D scans have been used as proxies for overall shape. Here we demonstrate that 3D geometric morphometrics (GM), under the “Procrustes paradigm” and coupled with a Bayesian approach, probabilistically discriminates between marks caused by different butchery behaviors. At the same time, this approach provides a complete set of 3D morphological measurements and descriptions. Our results strengthen statistical confidence in cut mark identification and offer a novel approach that can be used to discriminate subtle differences between cut mark types in the fossil record. Furthermore, this study provides an incipient digital library with which to make future quantitative comparisons to archaeological examples, including contentious specimens that are key to understanding the earliest hominin butchery.

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Formation, morphology and interpretation of darkened faecal spherulites

Posted on December 2, 2017 by ARCAS

Publication date: January 2018Source:Journal of Archaeological Science, Volume 89 Author(s): M.G. Canti, C. NicosiaFaecal spherulites are a common indicator of dung in archaeological deposits and most of the basic processes of their formation and taphonomy have been explained. However, a darkened form is also regularly found, ranging from slightly transparent through to completely opaque. These have been less well studied, so we set out here to understand what actually causes the darkening and to determine the range of conditions required to produce the changes.Darkened spherulites were successfully created by heating dung to between 500 °C and 700 °C with the gaseous products constrained. The maximum production in our experiments was at 600 °C. The darkened spherulites often expanded during the alteration process and some of the expanded ones become distorted. SEM examination was only possible through destructive preparation processes, but examples were found showing expansion beyond the normal size range. These had a distinctive internal structure characterised by very fine crystallinity and larger scale fracturing, perhaps resulting from organic matter loss and/or CaCO3 alteration. Prolonged oxidative heating failed to remove the darkening, leading to the possibility that it is partly a structural phenomenon, with opacification arising from compound relief.Based on these findings, darkened spherulites can now be confidently interpreted as; resulting from dung being heated in conditions of limited gaseous exchange to between 500 and 700 °C, then not heated again beyond ca. 700 °C. These sorts of conditions could occur, around the edge of, or beneath, any fire where fresh dung is; being burned or where the existing stratigraphy has a dung component.

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