Ula Thirra: a case study in the geomagnetic detection of combustion features in Channel Country of far south-western Queensland

The use of fire plays a vital role in studies involving human adaptation and evolution as well as landscape and environmental management, especially when it can answer questions about people’s movement across space, their resource availability and occupation (e.g., intensity and duration). The Australian landscape contains numerous combustion features making it particularly challenging to understand fire use, primarily due to erosional systems impacting in-situ deposits. Although they are one of the most easily recognizable features of past Aboriginal occupation, their preservation is a complex issue created by exposure through erosional processes in the form of wind and rain. This has added difficulties to developing interpretation surrounding how they reflect occupational intensity and understanding their use. The purpose of this case study is to explore several combustion sites to understand their geomagnetic signatures in relation to their environmental setting and how these vary based on erosional processes and geomorphology. Using magnetic gradiometry, we mapped six combustion sites in the Channel Country of far south-western Queensland, an arid central desert landscape characterized by low gradient fluvial and aeolian sedimentation (e.g., sand dunes). Results indicate that many of the geophysical signatures were largely dependent on the site’s geomorphological history but that there was a strong potential for intact combustion features. This has important implications for cultural heritage management and our research partners, the Mithaka Aboriginal Corporation, who seek ways to monitor sites affected by erosion and ground-test sites where information about past land use can be studied.