Before the commencement of the gradiometer surveys testing was conducted over known fire rocks in order to establish the intensity of readings that may be experienced. Testing was conducted at blowout A, as there is an abundance of limestone fire rock lying on the surface of the dunes. These fire rocks may well have been in-situ hearths but have since been uncovered as the dune has eroded away. When I conducted the test it became apparent that not all of the fire rocks gave a strong magnetic reading when traversed with the gradiometer. By accident a theory has arisen as to why this is the case. When testing, a particular fire rock (figure 2) was traversed and gave a high magnetic reading of -24 nT (figure 1). It was picked up off the ground and analysed and set back down in the same position, though by accident it was turned over before being set down again —meaning that the opposite side was then facing upwards. When traversed again the readings were very low (1nT), so my theory is that the face of the rock providing the high readings was the side of the rock that experienced the fire event—hence containing the remnant magnetisation—whilst the other side did not. This seemed to be the case for many of the other rocks tested in this way. There needs to be much more study done in this area, but further testing was beyond the scope of this paper, though this did bring about questions regarding the survey. If the hearths were no longer in-situ and individual stones were shuffled around due to an ever moving dune system, would they be able to be detected by magnetic methods if the fired surface of each rock was not facing upwards? The small amount of testing done during this study would indicate that they would not.
TagsAboriginal Affairs and Reconciliation Division Aboriginal Affairs Victoria Aboriginal Australia Aboriginal Heritage Act 1988 Archaeology Archival research Artefact Photography Artefacts Australia Boord House Burial sites Cape York Peninsula Central American Archaeology City of Marion City of Unley Coastal Archaeology Cultural Heritage Management Department of Indigenous Affairs Directed Study Excavation Field methods Field School Fieldschools Fieldwork Flinders University Geophysical Techniques Global Positioning System Griffith University Heritage Legislation Hinchinbrook Island Historical Archaeology Indigenous Archaeology Kangaroo Island Kaurna Lady Alice Mine Legislation Mallala Marion City Council Maritime Archaeology Master Class Mitcham Heritage Research Centre Modbury Museum Collections National Trust of South Australia News Ngadjuri Ngarrindjeri Norman Tindale Oatlands Gaol Our Achievements Our Staff Our Students OzArk Photography Port Adelaide Port MacDonnell Queensland Repatriation Seven Stars Hotel shipwreck Shipwrecks South Australia South Australian Museum South Australian Museum Archives Space Archaeology Stone artefacts Stone Tools Student Placements Tea Tree Gully Thesis Research University of Adelaide Unley Museum Victoria Weipa World Archaeological Congress