Heart of darkness: an interdisciplinary investigation of the urban anthropic deposits of the Baptistery of Padua (Italy)

Archeological excavations beside the Baptistery of the Dome of Padua (north-eastern Italy) unearthed anthropic deposits formed between the seventh- and tenth-century ad. These were analyzed using soil micromorphology, soil chemical analyses (especially aimed at the definition of organic matter properties and dynamics), and GC/MS analyses of fecal biomarkers, the latter corroborated by principal component analysis. This inter-disciplinary study allowed differentiating between units resulting from in situ accumulation of trampled domestic waste and other, more frequent, units derived from repeated dumping or backfilling episodes. Fast accumulation of organic-rich domestic waste, coupled with an incomplete evolution of organic molecules appears as a fundamental formation process of these anthropic deposits. The overall level of fecal contamination in the Padua Baptistery sediments proved to be very low or absent.