Bayesian inference with Monte Carlo approximation: Measuring regional differentiation in ceramic and glass vessel assemblages in Republican Italy, ca. 200 BCE–20 CE

Posted on February 21, 2017 by ARCAS

Publication date: April 2017Source:Journal of Archaeological Science, Volume 80 Author(s): Stephen A. Collins-ElliottMethods of measuring differentiation in archaeological assemblages have long been based on attribute-level analyses of assemblages. This paper considers a method of comparing assemblages as probability distributions via the Hellinger distance, as calculated through a Dirichlet-categorical model of inference using Monte Carlo methods of approximation. This method has application within practice-theory traditions of archaeology, an approach which seeks to measure and associate different factors that comprise the habitus of society. It is implemented here focusing on the question of regional food consumption habits in Republican Italy in the last two centuries BCE, toward informing a perspective on mass social change.

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Editorial Board

Posted on February 18, 2017 by ARCAS

Publication date: March 2017Source:Journal of Archaeological Science, Volume 79

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European cobalt sources identified in the production of Chinese famille rose porcelain

Posted on February 16, 2017 by ARCAS

Publication date: April 2017Source:Journal of Archaeological Science, Volume 80 Author(s): Rita Giannini, Ian C. Freestone, Andrew J. ShortlandThe blue pigments on 112 fragments or small objects of Qing Dynasty Chinese, 95 of underglaze blue and white and 17 overglaze enamelled porcelains were analysed by LA-ICPMS. The underglaze blues on both blue and white and polychrome objects were created with a cobalt pigment that was rich in manganese with lesser nickel and zinc. This suite of accessory elements is generally considered to be characteristic of local, Chinese, sources of pigments. However, the blue enamels were very different. The cobalt pigment here has low levels of manganese and instead is rich in nickel, zinc, arsenic and bismuth. No Chinese source of cobalt with these characteristics is known, but they closely match the elements found in the contemporary cobalt source at Erzgebirge in Germany. Textual evidence has been interpreted to suggest that some enamel pigment technologies were transferred from Europe to China, but this is the first analytical evidence to be found that an enamel pigment itself was imported. It is possible that this pigment was imported in the form of cobalt coloured glass, or smalt, which might account for its use in enamels, but not in an underglaze, where the colour might be susceptible to running. Furthermore, the European cobalt would have given a purer shade of blue than the manganese-rich Chinese cobalt.

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Export Chinese blue-and-white porcelain: compositional analysis and sourcing using non-invasive portable XRF and reflectance spectroscopy

Posted on February 16, 2017 by ARCAS

Publication date: April 2017Source:Journal of Archaeological Science, Volume 80 Author(s): Christian Fischer, Ellen HsiehThe chemical composition of Chinese blue-and-white porcelain, from the body to the pigment and the glaze, has been widely investigated over the last decades. However, most studies focused on ware from official kilns and much less attention has been given to folk kilns whose production was primarily aimed at supplying overseas markets. Moreover, scientific analysis has often relied on sophisticated laboratory-based instrumentation, a methodology that can be used neither for large sets of archaeological sherds nor in the field. The research presented here evaluates the applicability of non-invasive portable X-ray fluorescence (pXRF) and fiber optics reflectance spectroscopy (FORS) for the study of overseas Chinese blue-and-white porcelain manufactured in Jingdezhen and Zhangzhou, the main production centers during the late 16th to early 17th centuries. Results obtained on a limited number of sherds found in Indonesia and the Philippines show that concentration levels of some minor and trace elements, in particular zirconium and associated thorium, are sufficient to clearly distinguish Jingdezhen and Zhangzhou productions. The composition of the cobalt-based blue pigment was also easily identified with pXRF, highlighting the Fe-poor and Mn-rich compositional pattern in accordance with the local asbolite ores used during this time period. Furthermore, FORS provided additional information on tint and shade variations of the blue pigment. Consequently, pXRF combined with FORS represents an innovative and cost effective analytical approach to study the chemistry and provenance of Chinese blue-and-white porcelain, particularly in the field and/or for large archaeological sherd collections.

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Origins of inhabitants from the 16th century Sala (Sweden) silver mine cemetery – A lead isotope perspective

Posted on February 11, 2017 by ARCAS

Publication date: April 2017Source:Journal of Archaeological Science, Volume 80 Author(s): T. Douglas Price, Robert Frei, Ylva Bäckström, Karin Margarita Frei, Anne Ingvarsson-SundstromHistorical documents record the operation of a silver mine from the 16th century AD located near the former village of Salberget in central Sweden. The historical record describes several categories of inhabitants, including local families, workers and miners, foreign engineers and mining specialists, as well as war captives and criminals used as forced labor in the mines. A church yard in the vicinity of the village served as a burial ground. Archaeological evidence indicates two distinct grave types (coffin and earthen) and physical anthropology documents differences in age and sex between these grave types, as well as harsh conditions of life. Strontium and oxygen isotopes have been used previously to investigate the place of origin of the cemetery inhabitants and clear differences among the types of graves were seen in the isotope results. Place of origin was more difficult to ascertain however. Here we utilize lead isotopes as an additional isotopic tracer to identify origins. The lead isotope investigations pinpoint several areas outside of the Sala region where some of the inhabitants originated. In addition, the study documents the benefits of using lead isotopes in human proveniencing studies.

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Preparing the foundation for stable gilding: Baroque craftsmen’s empirical understanding of gesso gilding grounds

Posted on February 10, 2017 by ARCAS

Publication date: Available online 9 February 2017Source:Journal of Archaeological Science Author(s): Isabel Pombo Cardoso, Elizabeth PyeThis paper is the fourth in a series covering Portuguese gesso gilding grounds from the late 13th to the 18th century, but with a special focus on the Baroque period when gilded surfaces played an important religious, political and social role in Portugal. This fourth paper concentrates on unravelling the motives of the craftsmen who chose to produce grounds for gilded surfaces using very specific materials and techniques: gypsum, as the raw material, and a double-structured layered system. It seems plausible that the properties of this type of ground, the religious and social importance and the function of the gilded objects, cultural influences from southern European, and the particular Portuguese historical context all contributed to this choice. This paper aims to contribute to enrich understanding of gilding technology and to inform conservation decision-making for the preservation of these gilded objects.

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Movement of lithics by trampling: An experiment in the Madjedbebe sediments, northern Australia

Posted on February 7, 2017 by ARCAS

Publication date: March 2017Source:Journal of Archaeological Science, Volume 79 Author(s): Ben Marwick, Elspeth Hayes, Chris Clarkson, Richard FullagarUnderstanding post-depositional movement of artefacts is vital to making reliable claims about the formation of archaeological deposits. Human trampling has long been recognised as a contributor to post-depositional artefact displacement. We investigate the degree to which artefact form (shape-and-size) attributes can predict how an artefact is moved by trampling. We use the Zingg classification system to describe artefact form. Our trampling substrate is the recently excavated archaeological deposits from Madjedbebe, northern Australia. Madjedbebe is an important site because it contains early evidence of human activity in Australia. The age of artefacts at Madjedbebe is contentious because of the possibility of artefacts moving due to trampling. We trampled artefacts in Madjedbebe sediments and measured their displacement, as well as modelling the movement of artefacts by computer simulation. Artefact elongation is a significant predictor of horizontal distance moved by trampling, and length, width, thickness and volume are significant predictors of the vertical distance. The explanatory power of these artefact variables is small, indicating that many other factors are also important in determining how an artefact moves during trampling. Our experiment indicates that trampling has not contributed to extensive downward displacement of artefacts at Madjedbebe.

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Heat impact and soil colors beneath hearths in northern Sweden

Posted on February 4, 2017 by ARCAS

Publication date: March 2017Source:Journal of Archaeological Science, Volume 79 Author(s): Lars Liedgren, Greger Hörnberg, Tord Magnusson, Lars ÖstlundThe archaeological remains of Sami hearths in boreal and subarctic areas of northern Sweden are common finds. Greater understanding of the effects of heat on soil coloration will facilitate interpretation of the main purpose of these hearths, for example as heat sources or for cooking or other processing, and whether they were used seasonally for long or short periods of time. We therefore studied effects of heat on the coloration of natural B-horizons beneath traditional Sami hearths using three approaches: firing with dry pine wood in experimental hearths and measuring the temperature at various levels beneath the hearths; laboratory heating of B-horizon soils at different temperatures (200–900 °C) in a muffle oven and; measuring soil color changes in terms of RGB-values, and comparing the experimental results with soil profiles beneath real hearths used by nomadic Sami reindeer herders in northern Sweden. The study shows that the temperature reached beneath hearths strongly depends on the type of fuel used and the length of firing. The temperature can rise rapidly in upper layers of the soil but it takes considerable time for heat to penetrate 20 cm below the hearth surface. Our experimental firings, for 10 h on three consecutive days and for 72 consecutive hours, resulted in bowl-shaped areas of discoloration, with strong red coloration (rubification) towards the edges and dark grey/brown discoloration in the middle of the hearths in both tests. After laboratory heating, soil samples darkened during temperatures of 200–300 °C, and rubification at 250–350 °C depending on the amount of humus in the soil. The RGB analysis showed a steady increase in rubification from 300 °C, peaking at 750–800 °C. We believe that the rubification is caused mainly by transformation of iron compounds to maghemite and hematite and that the quantity of hematite is determined by temperature and not by time.Excavations of ancient hearths also revealed examples of bowl-shaped discoloration in B-horizons deeper than 20 cm. These discolorations had a rather uniform red tone with no dark areas. This suggests that the darker areas, probably colored by reduced iron and not by charred particles, could have been altered over time. The main conclusion is that rubification in B-horizons beneath hearths can arise after a relatively short period of firing but-bowl shaped areas of deep coloration can only arise, in boreal and subarctic areas, when hearths have been fired heavily and continuously for long periods of time, indicating winter use.

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Preparing the foundation for stable gilding: Scientific evaluation of the durability of Baroque gesso gilding grounds

Posted on February 3, 2017 by ARCAS

Publication date: Available online 2 February 2017Source:Journal of Archaeological Science Author(s): Isabel Pombo Cardoso, Elizabeth PyeThis paper follows two earlier papers about Portuguese gesso gilding grounds, a typical decoration from the 13th to the 18th century but with a special focus on the Baroque period. It concentrates on understanding the reasons why these gilded surfaces are so durable. The main concerns of the people involved in the production of the gilded surfaces, as revealed in contemporary historical documents, are the quality and durability of the decorations. The investigation of ‘durability’ involved the study of factors not explored before regarding materials and practices commonly used to produce gilded wooden surfaces in South Europe. The paper discusses the probable effects on durability of loading a binder with a filler, of the shape and size of the filler particles, of the interaction of filler and binder, and of using a multi-layered system; it discusses the science underlying the use and behaviour of particular gilding materials and practices.This paper is followed by a second paper focused on technological choices. Together they aim to contribute to understanding why Portuguese gilders clearly chose double-structured gesso grounds in preference to other possibilities, and to aid on conservation decision-making and the design of new strategies for the treatment and preservation of these historical gilded surfaces.

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