Alluvium of antiquity: Polycyclic terraces in a confined bedrock valley

► The Shoalhaven River has archived mid-Pleistocene alluvium in a confined valley. ► Terraces up to 193 ka in age (MIS 7) are within reach of the modern floods. ► This polycyclicity appears to be a response to flow reduction. ► Terraces help maintain a relatively uniform channel to carry a wide range of flows. ► Alluvium is used to adjust the boundary of the otherwise inflexible bedrock gorge.