Petroglyphs as petrofacts? Exploring the visibility and physicality of lines, furrows, and cavities in Bronze Age rock art

Abstract This text concerns tangible and sensory aspects of petroglyph production with a primary focus on south Scandinavian Bronze Age rock art. The core of the study is based on an experimental trial of making a cupmark, a circle motif, and a shallow boat motif on a small granite outcrop. The aims were to measure time expenditure, the impact of water on the process, evaluate sensory aspects (e.g. colour, sound, and smell), and measure the visibility of the petroglyphs over time. The direct results of the experiment show that a cupmark can be produced within 12 minutes and a circle within an hour, using a direct technique with a small pointed hammerstone. The shallow boat motif took only seven minutes to make and was almost as visible (white) as the deeper circle motif, even without leaving any measurable depressions in the rock. The results of the present study are related to other published trials concerning Bronze Age rock art. This paper concludes that petroglyphs are probably less about making illustrative or communicative imagery but more about producing petrofacts: ritual devices with physical abilities, such as producing mineral dust or gathering and channelling water or other liquids.