Palaeoclimatic support for the Pleistocene 'superhighway' through central Australia

Abstract

Our understanding of the climatic conditions faced by humans upon arrival in Australia is both temporally and spatially fragmented. A cave in the Ikara-Flinders Ranges contains speleothems that shed light on the palaeohydrology of Australia’s southern arid margin through the Last Glacial Period. The timing of speleothem growth phases suggests there were three multi-millennial periods where the region experienced a more positive water balance, each of which aligns with Southern Hemisphere summer insolation maxima. This implies that moisture delivery was governed by the strength and/or latitudinal position of the Indo-Australian Summer Monsoon, meaning the continental interior to the north of the cave site would also be receiving monsoonal rainfall. These findings support the proposed ‘superhighway’ through central Australia (Crabtree et al. 2020; Bradshaw et al. 2023). A period of especially high moisture availability coincides with the earliest evidence of human presence at the Warratyi shelter, 250 km north of the cave site (Hamm et al. 2016).