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A series of ten red horizontal lines, recently rediscovered in Bacon Hole on the southern coast of the Gower Peninsula in Wales, has been interpreted as rock art possibly dating to the Upper Palaeolithic period c.17,100 years ago. If this date is correct, it would make the markings the oldest known rock art yet discovered in Britain.
The rock art panel was originally found by Professor William Sollas and Henri Breuil in 1912 (see CA 197), but, while their discovery made international headlines, by 1928 the horizonal bands were deemed to be a natural phenomenon. The markings were all but forgotten for almost 100 years, but in August 2022 they were rediscovered by Dr Barbara Oosterwik from the University of Exeter, during a survey of the cave carried out by the First-Art Team – an international group of researchers specialising in analysing rock art from around the world – on behalf of the National Trust, which owns the site. Several fieldwork expeditions to the cave followed in 2023 and 2024, with contextual support (in terms of understanding the geomorphology of the cave) provided by the University of Swansea.
The cave comprises two chambers: the principal gallery and a smaller eastern side-chamber, and it is on the rear eastern wall of this latter space that the artwork was found. During their investigations, the team took photographs of the chamber walls and then used a colour-filter algorithm, known as Decorrelation Stretch (DStretch), to isolate the red pigment and better identify deliberate paint markings, even when obscured under thick crusts of calcite. In this way, as well as locating the horizontal bands, the researchers were able to identify other markings, including geometric forms, finger dots, and spreads of pigment that may have been created through spitting or blowing paint on to the wall.
Above & below: The painting as it appears today, and the same image analysed using DStretch to isolate the red pigment.
In order to date the painting and analyse the pigment, the team took 12 samples (six from each visit to the cave, with the initial sampling programme undertaken by University of Southampton researchers, and a second by First-Art), which were analysed by geochemists from Nanjing University, China. Samples taken from the calcite crust layers on top of the pigment were used to provide a minimum date range through uranium-thorium dating (U-Th), and while many unfortunately proved to be contaminated or not close enough to the pigment to provide an accurate date, one of the samples was able to provide a minimum date of c.17,100 years ago. This would place the rock art’s creation in a period when this part of Wales was gradually emerging from the Devensian glaciation. The landscape would have been shifting to one more habitable for humans, with the area now occupied by the Bristol Channel probably serving as an ideal location for hunting migratory megafauna during the summer months. As this date is only derived from one sample, however, the team remain cautious, and they plan to return to the cave to obtain another series of samples to help confirm and refine their results.
Samples of the pigment itself were also analysed to determine its chemical composition. This revealed that the paint was predominantly made of haematite, which could have been sourced from within the cave itself. Varying quantities of aluminosilicate residues within the samples suggest that there were at least two distinct ‘recipes’ for the paint involved in creating the artworks.
Overall, between all these characteristics, the team are confident that this panel was indeed purposefully created by humans, and that they have finally settled this 114-year-old debate. Their full results were recently published in Quaternary (https://doi.org/10.3390/quat9030043).
Text: Kathryn Krakowka / Photo: George Nash
