Unveiling rock art images: A pilot project employing a geophysical technique to detect magnetic signatures

01st December 2010

Jennifer Milani

M. Archaeology, Department of Archaeology, Flinders University, October 2010

The use of geophysical techniques in archaeology has become widespread, however these methods have rarely been applied to rock art research. There is a need to record and document rock art images as they face deterioration from environmental, industrial and human impacts. This project trials the use of a magnetic susceptibility (MS) meter to non-invasively detect and spatially resolve ochre rock art images. Ochre is frequently used in rock art production and previous research in other contexts has shown that it emits a MS signature due to its inherent magnetic characteristics. These ochre images can be hidden behind silica or carbonate crusts or may deteriorate over time limiting their visibility. The rock art images that lie behind such crusts are likely to be protected from weathering and are amenable to dating using such techniques as uranium-series and radiocarbon accelerator mass spectrometry (AMS).

This research demonstrates that, if present in sufficient abundance, red ochre can be imaged and spatially resolved with a MS meter when applied to a rock face in a variety of geological environments. The type of binder used, pre-application heating or the rock type does not appear to have a significant effect on the viability of the technique. More important to the success of a survey is the equipment setting, spatial resolution of the survey and the use of a correction to control instrument drift. Imaging ochre beneath a proxy crust was trialled without success; however this is attributed to poor survey design rather than a fundamental problem with the technique. The success of this trial demonstrates the validity of continuing investigations in the emerging field of rock art geophysics and highlights the importance of future trials on field sites.

Jennifer Milani
Unveiling rock art images: A pilot project employing a geophysical technique to detect magnetic signatures
December 2010
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Thesis Abstracts
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