Anthropogenic signatures in the heart of Prague: Urban Dark Earth and soil–sediment processes in a medieval marketplace

Urban Dark Earth deposits represent key archives of anthropogenic processes in medieval Europe, yet they remain insufficiently studied in Central European contexts. This paper presents a multi-proxy investigation of stratified sediments from Wenceslas Square in Prague, a planned urban market established in 1348. Micromorphology, pXRF geochemistry, magnetic susceptibility, grain size, stable C and N isotopes, Pb isotopes, and biomarker analyses were applied to document the transformation from pre-urban colluvial and loess-derived sediments into organic-rich Dark Earth. Pre-1348 horizons are dominated by silt-rich (loess-derived) sediments with low anthropogenic input; only episodic high-energy rainfall events (e.g. AD 1280) introduced a distinct fine-grained, silt-dominated run-off layer. After the mid-14th century, the stratigraphy becomes more texturally variable (from silt-rich to sandier horizons) and is enriched in Ca, P, S, Pb, organic matter, and waste-derived compounds. Micromorphological evidence, including phosphate mineralization and vivianite, indicates intensive deposition of organic refuse. Biomarker data indicate repeated fecal inputs of mixed origin, most likely including animal dung and possibly human waste, supported by coprostanol, bile acids, and phytosterols, while Pb isotope ratios trace contributions from medieval smelting. Together, these datasets demonstrate how the planned foundation of the New Town triggered sustained anthropogenic accumulation, creating a distinct Dark Earth deposit that differs from earlier Western European examples by its younger age and explicit association with proto-industrial activities.