Earth constructions in Empúries: Building techniques in Greek and Roman periods in the Iberian Peninsula

This study examines the raw earth materials and construction techniques employed in Greek and Roman architecture at the Empúries archaeological site through granulometric, geochemical, mineralogical, and micromorphological analyses. The results reveal clear differences between the two periods. Greek constructions used fine, clay-rich soils derived from Mediterranean red soils developed on limestones and ancient fluvial terraces, whereas Roman buildings relied on sandier matrices sourced from the more recent Fluvià River deposits. Micromorphological observations show higher porosity and juxtaposed structures in adobe materials, in contrast with the apedal, dense, and better-compacted fabrics characteristic of Roman rammed earth (RE). Cation Exchange Capacity (CEC) values further support this distinction, reflecting the use of soils with expansive clays versus more inert sandy matrices. Overall, the findings indicate the use of local soils without deliberate mixing, but with distinct technical choices. The imperial-period sample exhibits intermediate features, with high bulk density yet less controlled micromorphological traits, suggesting heterogeneous construction practices. This integrated dataset deepens our understanding of ancient building strategies and their relationship with local geology and cultural traditions.