Soil Forensic Investigations of Frontier Conflict Sites In Far North-Western Australia Using Advanced XRD Techniques.

Following the west to east exploration of the Kimberley region in the far north of Western Australia by Alexander Forrest in 1879, pastoralists and miners flocked to the region in their thousands. Many of the indigenous Aboriginal population numbering some 30,000 were dispossessed of their land. The period between 1920 and 1939 experienced extreme drought conditions. Consequently, many Aboriginal people were forced to move to fringe camps close to the cattle station homesteads, where permanent waterholes were prime locations. Conflict between colonists and local indigenous populations inevitably arose and resulted in many Aboriginal deaths.

 One such site, Goolamuru on the Panton River appears to be the location of a massacre and subsequent cremation of Aboriginal remains. Unfortunately investigations have so far failed to determine if the many bone fragments recovered from the site are animal or human. Undisturbed cores were taken along transects at the site. Field evidence suggests the site has been subjected to prolonged exposure to temperatures exceeding 500°C. Advanced X-ray diffraction techniques were used to analyse the soils and bone fragments. Comparison with laboratory experiments on animal bone has enabled estimations of temperature and length of heating to be made. Crystallite size was determined at several temperatures and heating durations and compared against the crystallite sizes determined for bone fragments from the site.

 Hydroxylapatite [Ca₅(PO₄)₃(OH)] was found in most soil samples, with the exception of samples at depth (10-20 cm) in profile A2. The crystallinity of the hydroxylapatite phase (determined by the sharpness of the apatite XRD peaks) shows some bone fragments are poorly crystalline, most typical of relatively low temperature heating. Hydroxylapatite in soil profiles and some surface sample fragments are well crystalline, indicating that these bone materials were likely heated to greater than 500°C for a considerable length of time. Comparison between XRD patterns of the bone fragments with laboratory heated bone indicates significant changes in degree of hydroxylapatite crystallinity, enabling temperature and duration of heating to be determined.