Alluvial geoarchaeology of an ephemeral stream: Implications for Holocene landscape change in the central part of the Ebro Depression, northeast Spain

Abstract

La Virgen is an ephemeral tributary of the Ebro River in northeast Spain with a complex alluvial sequence. We analyzed alluvial stratigraphy to develop a model of Holocene fluvial evolution for La Virgen and infer causes of floodplain dynamics. Three alluvial terraces were mapped and described using a combination of geoarchaeological and geomorphological techniques. Stratigraphic ages were estimated using 14C dating and archaeological remains. Sedimentation in the valley floor commenced in the Neolithic period ca. 6000 BC and continued during the Bronze and Iron ages (ca. 1800–500 BC), the Iberian and Roman periods (ca. 500 BC–AD 500), and the Middle Ages (ca. AD 500–1500). The main terrace (N3) is 14m thick and predominantly composed of sand, silt, and clay that we believe are derived from local hillslopes and represent a long period of human-induced soil erosion that intensified during the Bronze and Iron ages until the Late Roman period