The palaeogeography of the Bass Strait land-bridge, a vital zone of human and biological connectivity across southeastern Australia

Land-bridges are key regions of human connectivity, yet how geography affected peoples' movement during flooding is poorly understood. Bass Strait is one of the most important land-bridges in Australasia, separating Lutruwita/Tasmania from the mainland of Australia. The land-bridge forms a key part of Country among the region's First Peoples, with people able to move across the clan estates and residential places of the exposed Bass Strait by foot until its flooding after the Last Ice Age. In this study, we utilise high-resolution bathymetry to understand landscape change during sea-level rise. We find that rates of shoreline transgression can exceed 30 m/yr, signalling that 15 km of land would have been drowned in a persons lifetime. This rapid rate of change is within a person's life-span and would have profoundly affected individuals as they resided in and travelled across Country. We also find that people first crossed the land-bridge very soon after its exposure during climate cooling events. The analysis provides a benchmark for understanding land-bridge flooding and in turn its impact on human migrations. • Land-bridges are key regions of human connectivity. • Horizontal rather than vertical shoreline movement is critical for species movement. • Rates of shoreline change are observable on human timescales exceeding 30 m/yr. • Shelf slope is key for parameterisation.