Charred micro-particles characterization in archaeological contexts: Identifying mixing between sediments with implications for stratigraphy

Yotam Asscher, Elisabetta Boaretto

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Charred micro-remains in archaeological sediments vary from large destruction layers, to localized lenses, and they are invaluable stratigraphic anchors when found in situ. Visual observations of black sediments are a good marker for primary depositions of burning events, however, an independent criteria is necessary to verify these sediments were not mixed with other contexts. In this study, a microarchaeological approach was used to quantify charred micro components in sediments from a pyrotechnological pit at Qubur el-Walaydah, allowing the assessment of their diffusion between sediments. Organic micro-particles were purified from black lenses in situ and their surrounding sediments, based on their density, showing the organic fraction is composed of particles that are lighter than a density of 1.7 g/mL and smaller than 1 mm3. Thermal and structural characterizations show that the micro-particles from black lenses are charred between 30 and 40%, compared with 5% in the surrounding sediments. A new method to quantify the charred micro-particles was developed based on microscopy, showing black lenses and hearths have between 40,000–110,000 charred micro-particles per gram of sediments, while their surrounding archaeological sediments have less than 20,000. These results show micro-particles could be purified and characterized, providing a quantifiable approach for assessing mixing between sediments based on particles concentrations. One application is micro-stratigraphic interpretations of primary depositions, allowing portable microscopes on-site to assess the mixing between sediments. Another application is to include the charred micro-particles in the radiocarbon dating assemblage as evidence for in situ burning. Dating charred micro-remains should be used only to solve chronological questions that do not require high resolution accuracy, when cultural material and macro-charred remains are not found.

Original languageEnglish
Pages (from-to)32-39
Number of pages8
JournalJournal of Archaeological Science
Volume107
DOIs
StatePublished - Jul 2019
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2019 Elsevier Ltd

Funding

Funding was provided by the Kimmel Center for Archaeological Science . The Radiocarbon Research was supported by the Exilarch's Foundation for the D-REAMS Radiocarbon Dating Laboratory. E.B. is the incumbent of the Dangoor Professorial Chair of Archaeological Sciences. We would like to gratefully acknowledge the generous financial help from Mr. George Schwartzman. We would like to thank Dr. Michael Kerschnitzki for his support in the image processing of the optical micrographs.

FundersFunder number
Exilarch's Foundation

    Keywords

    • Dating assemblage
    • Micro-charred remains
    • Primary contexts
    • Radiocarbon

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