Holocene aggradation history of the Murcia alluvial valley: Insights into early Rome's paleoenvironmental evolution

Abstract

Through the analysis of seven 15–30 m deep boreholes drilled in the western sector of the Circus Maximus we reconstruct the aggradational history of one main tributary valleys of the Tiber River in Rome, the Murcia Valley (Vallis Murcia). Consistent with recent acquisitions in the Tiber Valley, we identify a Bronze Age (4500-3000 yr BP) paleogeographic setting characterized by the lowering of the drainage network base level. This would have created a dry alluvial plain, suitable for human settlement. We also find evidence for dramatic overflooding which occurred during the 6th century BCE and was responsible for the rapid rise from 2 to 6 m a.s.l. of the valley floors within the Tiber catchment basin in Rome. We suggest that these paleogeographic features can be identified in mythical and ethno-historical accounts of early Rome.Besides providing insights into the paleolandscape and anthropogenic interventions in the Murcia Valley, these previously unrecognized hydrological dynamics may attest to paleoclimatic fluctuation that have occurred since 5000 yr BP. Contrary to the dry and cold conditions prevalent during the Bronze through the Iron Age, the exceptional flooding events of the archaic period suggest a shift in climatic trends. However, tectonic and anthropogenic factors could have also had a combined and cumulative effect, requiring detailed paleoenvironmental and palaeolandscape studies.