In regions that lack built structures or stratified open archaeological sites, such as precolonial Australia, rockshelters are a major source of detailed information for understanding the nature and timing of human occupation. A key concern is that the proposed ages for the earliest archaeological sites are based on luminescence dating of sediments, rather than directly of cultural materials, leaving the association between the sediments and evidence of human activity questionable. Here, we present evidence of magnetic enhancement associated with cultural horizons within the deposits of a Pleistocene rockshelter in interior northern Queensland. Soil magnetic studies combined with experimental burning show that magnetically enhanced sediments in Gledswood Shelter 1 are the result of anthropogenic burning of hearth fires, which burn hotter and for a longer time than natural wild fires. These techniques appear to work in this setting because of the nature of the local geology and the geological antiquity of the landscape. Susceptibility and frequency dependence of susceptibility signatures provide a critical tool to resolve that human occupation starts at 2.2 m depth within a stratigraphic section. In conjunction with luminescence dating, soil magnetic studies provide an opportunity for archaeologists to resolve the timing of human settlement in Australia and other intracratonic plate settings.
Bibliographical noteFunding Information:
We thank Mike Jackson and Dario Bilardello from the Institute of Rock Magnetism, University of Minnesota for their assistance and feedback regarding the magnetic analysis, and Rinita Dalan from Minnesota State University Moorhead for helpful suggestions regarding this manuscript. We also thank the Woolgar Valley Aboriginal Corporation for supporting this research, Flinders University and the Australian Institute of Aboriginal and Torres Strait Islander Studies for funding the GS1 excavations and all those involved in the fieldwork. We like to thank Aaron Fogel as well as two anonymous reviewers whose comments greatly improved this manuscript. KML was funded by the Institute of Rock Magnetism, University of Minnesota Visiting Research Fellowship and the University of Queensland, through an International Postgraduate Research Scholarship and Centennial Scholarship, and a Graduate School International Travel Award.
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