High-resolution insights into protohistoric construction: a micromorphological study of gypsum use in earthen architecture in Gebut (Lleida, Spain)

The technique of soil micromorphology has seen a significant increase in its use over the past few decades. However, this tool is still underutilized in protohistoric sites in the Iberian Peninsula, despite having shown promising results. This work examines the use of gypsum as a construction materi...

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Bibliographic Details
Authors: Carbonell Roca, Joan, Bergadà i Zapata, M. Mercè, Alonso, Natàlia
Format: article
Status:Published version
Publication Date:2025
Country:España
Institution:Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya)
Repository:Recercat. Dipósit de la Recerca de Catalunya
OAI Identifier:oai:recercat.cat:2445/226187
Online Access:https://hdl.handle.net/2445/226187
Access Level:Open access
Keyword:Geoarqueologia
Geomorfologia
Protohistòria
Anàlisi dels sòls
Materials de construcció
Guix
Península Ibèrica
Archaeological geology
Geomorphology
Protohistory
Soil analysis
Building materials
Plaster
Iberian Peninsula
Description
Summary:The technique of soil micromorphology has seen a significant increase in its use over the past few decades. However, this tool is still underutilized in protohistoric sites in the Iberian Peninsula, despite having shown promising results. This work examines the use of gypsum as a construction material in the protohistoric site of Gebut, (Lleida, Spain), through a geoarchaeological study based on micromorphology. The results challenge the belief that gypsum can only be used in interior spaces or for decorative purposes. Its use has been identified in floors, plaster, and mortars, both in interior and exterior spaces. Additionally, parallels are drawn with other protohistoric sites in the northeast of the peninsula, where gypsum was used in mortars, plaster, structures related to liquid production, and waterproof floors. Under environmental conditions, gypsum tends to dissolve/precipitate and can naturally occurring at the site through various mechanisms. The study incorporates micromorphology criteria to distinguish between pedogenic and anthropogenic gypsum based on its general spatial arrangement, percentage, or the morphology and size of its crystals. Furthermore, adding specific temper (well-classified ceramic fragments and rubified aggregates) and plant fragments has been documented as very likely to improve mechanical properties and durability. These findings reveal advanced technical knowledge of gypsum in the Protohistoric period, involving pyro-technical skills, granulometric selection, and the use of natural additives to optimize its properties. The results encourage further physical-chemical studies to validate these hypotheses and reconsider gypsum’s role as a versatile structural material in protohistoric architecture.