The Geoarchaeology of Agricultural Terraces in Europe: Construction, Resilience and Implications for Sediment Delivery

Although the primary purpose of agricultural terracing can be assumed to be food production, it has been suggested that a secondary purpose was the control of soil erosion. In this paper, we explore this thesis with multi-proxy data from the TerrACE project, which studied 20 sites in a latitudinal transect across Europe. These sites show that terrace construction was often related to previous slope instability or erosion and that terracing maintained greater soil depths than the surrounding slopes. In some cases, it seems likely that the observation of landsliding that lowered slope angles and produced an accumulation of fractured regolith may have led to opportunistic terracing. The almost universal occurrence of multiple-phase sequences revealed maintenance and re-use that protected buried soil organic carbon. Three case studies show; headwater sediment and carbon retention by terracing, how terracing could be resilient to severe regional environmental events (eruption of Thera) and, lastly, the modelling of failure and sediment supply from vineyard terraces. Although there is no doubt that terracing reduced soil loss from slopes, whether the perception of an erosion risk was part of the conscious reasons for terrace construction is far harder to ascertain, but cross-cultural awareness of these factors does seem to be likely.