Soil geochemistry, phytoliths and artefacts from an early Swahili daub house, Unguja Ukuu, Zanzibar

Abstract

The organisation and use of space in domestic contexts remain challenging areas of investigation for archaeology due to the complexity and range of site formation and post-depositional processes. In tropical environments, soil processes speed up the degradation of archaeological and environmental records, and relatively ephemeral structures built of mud or clay degrade quickly after abandonment, leaving almost no traces of human activities behind. This paper presents the results of bulk soil and chemical analyses, artefact distribution, and phytolith analysis from the excavation of a daub house at the early medieval site of Unguja Ukuu (c. 7th–14th c. AD), Zanzibar. High-resolution, systematic sampling for microscopic and elemental analyses proved effective in detecting spatial variability in relatively small areas. However, soil chemical enrichment (e.g. Ca, Mg, Mn, P) usually linked to anthropogenic impact on archaeological deposits appears hardly visible in the Unguja Ukuu house deposits. Instead, measurements of a wider range of elements, including trace and rare earth elements (REEs) proved to be important for detecting elemental signatures related to human activities. Contextual sampling of artefacts and phytoliths were crucial to identify sources of chemical enrichment and, thus, build a picture of spatial organisation within the house. The combined multi-scalar sampling strategy with a multi-proxy analytical approach enabled us to define the layout of the daub structure, indoor/outdoor spaces and activity hot-spots. Although macroscopic traces of past activities were almost completely obliterated, archaeological remains of earthen architecture and the use of space can be detected even in such complex tropical settings.

Metadata

Item Type:

Article

Authors/Creators:

Wynne-Jones, Stephanie https://orcid.org/0000-0002-3005-8647
Sulas, Federica
Kristiansen, Soren Munch

Funding Information: The research presented here was supported by the Danish National Research Foundation under the grant DNRF119 - Centre of Excellence for Urban Network Evolutions (UrbNet) , Aarhus University . We are grateful to Rubina Raja and Søren Sindbæk for their support. Additional funding was provided by the Swedish Collegium for Advanced Study, Uppsala , the British Academy , and the School of Culture and Society , Aarhus University . Excavations and sample export were conducted under permits from the Department of Antiquities, Zanzibar , and in collaboration with Abdallah K. Ali, Director of Antiquities. We are especially grateful to the field team and close project collaborators (Abdallah K. Ali, Thomas Fitton, Ema Bauzyté, and Wolfgang Alders) and our assistants and hosts in Unguja Ukuu, for making us welcome and for providing invaluable information and support. For laboratory analyses and software help, we are grateful to AU Geoscience staff (Charlotte Rasmussen, Trine Ravn-Jonsen, Thomas Ljungberg and David Stott), Jesper Olsen and his team at the Aarhus AMS Centre. We extend our gratitude to two anonymous reviewers and Matthew Canti for valuable comments on an earlier version of this paper. Appendix A Publisher Copyright: © 2019. Published by Elsevier Ltd. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy.

Keywords:

Daub, Geoarchaeology, ICP-MS, Indoor vs outdoor space, Phytoliths

Dates: