Category Archives: 2010 # 2

2010 # 2

2010-10–DUFRAISSE-ET-ALII

The alteration of Neolithic wood charcoal
from the salt spring of Poiana Slatinei
in Lunca (Neamt, Romania):

a Natural Evolution or Consequence of Exploitation Techniques?

Alexa DUFRAISSE, Dominique SORDOILLET, Olivier WELLER

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Abstract

Located in immediate proximity to a salt spring still in use, the site of Poiana Slatinei in Lunca (Neamt, Romania) has yielded the earliest evidence of salt production in Europe (6050-5500 BC). It contains several dozen combustion features that form a large stratified mound of ashes, charcoal and rubified sediment layers.

In 2004, a vast sondage allowed detailed stratigraphic analysis and recording of the Early Neolithic levels and the collection of soil, charcoal and ash samples with the goal of more precisely identifying the techniques, management and interactions with the natural environment associated with salt production at this site.

While the micromorphological study led to the proposition of interpretations concerning the functioning of the fireplaces and the modes of salt exploitation, an anthracological analysis revealed a high degree of alteration of the wood charcoal fragments, or even the absence of ligneous structures. In this paper, we discuss this atypical preservation of charred particles through an analytical summary of the sedimentary, post-sedimentary and technical processes (choice of fuel material, evaporation method) observed at Lunca, and which could have played a role in their alteration.

To cite this article

Dufraisse A., Sordoillet D., Weller O., 2010 – The Alteration of Neolithic Wood Charcoal from the Salt Spring of Poiana Slatinei in Lunca (Neamt, Romania): a Natural Evolution or Consequence of Exploitation Techniques?, in Théry-Parisot I., Chabal L., Costamagno S., The taphonomy of Burned Organic Residues and Combustion Features in Archaeological Contexts, Proceedings of the round table, May 27-29 2008, CEPAM, P@lethnology, 2, 117-127.
2010 # 2

2010-11–REICHE

Heating and diagenesis-induced heterogeneities
in the chemical composition and structure
of archaeological bones from the Neolithic site
of Chalain 19 (Jura, France)

Ina REICHE

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Abstract

Bone materials, including numerous fragments of burned bones, are often found at archaeological sites. A comparative study of burned and unburned bone materials originating from the lacustrian site 19 of Chalain Lake, Jura, France, was conducted in order to assess their potential to yield information on past lifeways. The bones were analysed using various complementary physico-chemical methods (SEM-EDX, microPIXE/PIGE, FTIR, XRD, TEM-EDX) taking into account their chemical and structural heterogeneity. Through this “high resolution” approach, it was possible to observe the modifications of the bone mineral phase induced by heating and the processes of soil diagenesis, at the scale of the sample.

Our research has made it possible to distinguish the markers that characterise the diagenesis and heating of the specimens. The markers of heating could be used as quantitative indicators of the heating temperature reached by the bone prior to being buried. In addition, the results show different modification mechanisms depending on the possible heating of the bone prior to burying. Specifically, the concentration profiles determined on cross-sections by PIXE/PIGE make it possible to reveal an increase in exogenous chemical species at the centre of the heated sample, in contrast with the unburned bones which show higher concentrations of exogenous elements at the edge than at the centre. Thanks to the nanoscale structural analysis by transmission electron microscopy (TEM), it was possible to correlate the specific modifications of the elemental composition with the size of the apatite crystals present in the specimens.

This method can now be applied to other archaeological problems such as the investigation of various funerary customs or the taming of fire, in the knowledge that it can be applied to a small number of samples that must consequently be carefully selected from a larger corpus in order to be representative.

To cite this article

Reiche I., 2010 – Heating and Diagenesis-Induced Heterogeneities in the Chemical Composition and Structure of Archaeological Bones from the Neolithic Site of Chalain 19 (Jura, France), in Théry-Parisot I., Chabal L., Costamagno S., The taphonomy of Burned Organic Residues and Combustion Features in Archaeological Contexts, Proceedings of the round table, May 27-29 2008, CEPAM, P@lethnology, 2, 129-144.
2010 # 2

2010-12–LEBON

Characterization of burnt bones
in archaeological context:

a Comparative Study of Modern and Fossil Material
by Infrared Spectroscopy

Matthieu LEBON

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Abstract

The identification of burnt bones in an archaeological context can entail characterization techniques such as infrared spectroscopy. However, it is often difficult to clearly distinguish bones burnt at low temperatures (<500°C) because the alterations that occur during heating are similar to those that occur during burial. Moreover, these analyses are generally carried out on samples reduced to powder and they do not permit us to take into account the heterogeneity of the bone material.

In order to address these various problems, we became interested in the ν1ν3PO4 domain, whose study, on modern bones burnt under experimental conditions, allowed us to establish parameters that make it possible to evaluate the crystallinity of the samples (1030/1020 ratio) and to gather information on the crystal structure of the mineral phase (wavenumbers of the peaks centred near 961, 1022, 1061, and 1092 cm-1.) In particular, the wavenumbers of these various peaks have made it possible to identify bones burnt at temperatures as low as 250°C in the Magdalenian levels of the site of Bize-Tournal, while crystallinity by itself allowed only the clear identification of bones burnt above 500°C. This method can therefore contribute to an improved identification of bones burnt at low temperatures in an archaeological context. Moreover, this analytical protocol will make it possible to study the spatial variations in the composition of bone material by infrared micro-spectroscopy and thus to define and distinguish the alterations occurring during heating and during diagenesis.

To cite this article

Lebon M., 2010 – Characterization of Burnt Bones in Archaeological Context: a Comparative Study of Modern and Fossil Material by Infrared Spectroscopy, in Théry-Parisot I., Chabal L., Costamagno S., The taphonomy of Burned Organic Residues and Combustion Features in Archaeological Contexts, Proceedings of the round table, May 27-29 2008, CEPAM, P@lethnology, 2, 145-158.
2010 # 2

2010-13–ZAZZO

Isotope geochemistry of burned bones:

Implications for the Reconstruction of Diets and for Radiocarbon Dating

Antoine ZAZZO

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Abstract

Though they are frequently found at archaeological sites, burned bones have long been neglected by geochemists. After a brief review of the mineralogy and diagenesis of vertebrate skeletal tissues, all the physico-chemical changes induced by the high temperature combustion of bones are summarized. The implications of these changes for the reconstruction of diets through stable isotope ratios analysis and for the radiocarbon dating of bone remains are then discussed. It is thus shown that the high-temperature (>600°C) re-crystallisation of the mineral fraction of bones:

(1) provokes a fractionation of the isotopes that modifies the δ13C of the bone and therefore makes it unsuitable for paleodietary reconstructions;

(2) protects the bone from chemical interactions with the surrounding environment during fossilisation, thus making calcined bone a reliable material for radiocarbon dating.

The calcined bones can in turn be used to estimate the state of preservation of the unburned bones found at the same site when the collagen has not been preserved.

To cite this article

Zazzo A., 2010 – Isotope Geochemistry of Burned Bones: Implications for the Reconstruction of Diets and for Radiocarbon Dating, in Théry-Parisot I., Chabal L., Costamagno S., The taphonomy of Burned Organic Residues and Combustion Features in Archaeological Contexts, Proceedings of the round table, May 27-29 2008, CEPAM, P@lethnology, 2, 159-168.
2010 # 2

2010-14–COSTAMAGNO-ET-ALII

Taphonomic impact of prolonged combustion
on bones used as fuel

Sandrine COSTAMAGNO, Isabelle THÉRY-PARISOT,
Delphine KUNTZ, François BON, Romain MENSAN

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Abstract

The combustion of bones results in numerous processes whose impact on the representivity of fossil bone assemblages is increasingly well known due to the multiple experimental approaches developed over the last ten years. Recent experiments conducted with outdoor hearths have shown the consequences of prolonged combustion on bone combustion residues.

The average loss of bone mass after combustion is 65 %. The weight of the fine fraction (ashes and fragments less than 2 cm) corresponds to more than one quarter of the residual mass of the remains collected, while the mass of calcined (i.e. white) bone represents an average of 77.2 % of the residues. Finally, the residual bone mass is not correlated with the duration of use of a hearth, but with the manner in which it is maintained. These experiments thus clearly document the significant role of fire maintenance methods on the nature and form of bone residues.

To cite this article

Costamagno S., Théry-Parisot I., Kuntz D., Bon F., Mensan R., 2010 – Taphonomic Impact of Prolonged Combustion on Bones Used as Fuel, in Théry-Parisot I., Chabal L., Costamagno S., The taphonomy of Burned Organic Residues and Combustion Features in Archaeological Contexts, Proceedings of the round table, May 27-29 2008, CEPAM, P@lethnology, 2, 169-183.
2010 # 2

2010-15–GERBE

The action of weathering on burned bone:

an Experimental Approach

Magali GERBE

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Abstract

The alteration of bones following exposure to weathering is today well known, but it is possible that burned bones do not suffer the same type of changes since their physicochemical properties are modified by combustion. A series of experiments has been carried out with the aim of better understanding these reactions. These experiments form part of a more widespread attempt to better understand the impact of taphonomic agents on burned bones in order to estimate the distortions between bone material originating from experimental combustion and the fossil material.

Five experimental series resulting from the combustion of fresh cow humeri were exposed for eighteen months to weathering in a Mediterranean context. Several criteria were observed in order to highlight the impact of this exposure on the burned bones: degree of fragmentation, loss of bone mass, alteration of bone surface, influence of the degree of combustion (carbonised vs charred) and of the bone tissue (spongy vs compact) on the preservation of the material.

The results of these experiments mainly show a high fragmentation of the material (the small burned bones being in the majority), associated with a reduction in bone mass. In addition, spongy and charred bones have an increased sensitivity to the action of weathering, leading to their destruction. A preferential preservation of charred compact bone is thus expected.

To cite this article

Gerbe M., 2010 – The Action of Weathering on Burned Bone: an Experimental Approach, in Théry-Parisot I., Chabal L., Costamagno S., The taphonomy of Burned Organic Residues and Combustion Features in Archaeological Contexts, Actes de la table ronde, 27-29 mai 2008, CEPAM, P@lethnology, 2, 185-196.
2010 # 2

2010-16–RILLARDON-BRACCO

Reflections on the potential
for preservation of burned bone based on the material
from Saint-Antoine (Vitrolles, Hautes-Alpes)

Maryline RILLARDON, Jean-Pierre BRACCO

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Abstract

The faunal assemblage from the open-air site of Saint-Antoine at Vitrolles (Hautes-Alpes, Epigravettian) has yielded an atypical composition of burned bones (NRT = 23 %), being composed mainly of charred compact bones. While in an experimental context a high proportion of charred bones is typical of the use of skeletal remains as fuel, their representation in archaeological contexts is generally low, particularly in comparison to that of the less intensely burned elements. Contrary to this general principle, the Saint-Antoine deposit shows a strong representation of charred bones in a difficult taphonomic context characterised by an acid sediment and by the intensive action of different taphonomic phenomena (weathering, sediment compaction, dissolution). The high representation of charred bones seems to result from a combination of various factors, including the purpose of the combustion (camp maintenance and/or use as fuel) and their intense fragmentation, together with a higher preservation potential for burned bones (compact and spongy), including charred bones, compared to unburned bone elements when they are buried in acid sediments.

To cite this article

Rillardon L., Bracco J.-P., 2010 – Reflections on the Potential for Preservation of Burned Bone Based on the Material from Saint-Antoine (Vitrolles, Hautes-Alpes), in Théry-Parisot I., Chabal L., Costamagno S., The taphonomy of Burned Organic Residues and Combustion Features in Archaeological Contexts, Proceedings of the round table, May 27-29 2008, CEPAM, P@lethnology, 2, 197-208.
2010 # 2

2010-17–MORIN

Taphonomic implications of the use
of bone as fuel

Eugène MORIN

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Abstract

This paper explores the effects of the use of bone as fuel on archaeological skeletal part representation. Faunal data from the Paleolithic site of Saint-Césaire show that this activity may present an archaeological signature similar to that of differential preservation. The bones most frequently burned at Saint-Césaire are also those that are the least dense and that contain the most grease. The analysis of faunal remains from Saint-Césaire also suggests that spongy bone fragments from small-bodied and large-bodied taxa are subject to differential identification.

To cite this article

Morin E., 2010 – Taphonomic Implications of the Use of Bone as Fuel, in Théry-Parisot I., Chabal L., Costamagno S., The taphonomy of Burned Organic Residues and Combustion Features in Archaeological Contexts, Proceedings of the round table, May 27-29 2008, CEPAM, P@lethnology, 2, 209-217.