Vermiculations in painted caves: new inputs from laboratory experiments and field observations

Perrine Freydier (1) , Éric Weber (2) , Jérôme Martin (3) , Pierre-Yves Jeannin (2) , Béatrice Guerrier (1) , Frédéric Doumenc (1, 4)

1 FAST - Fluides, automatique, systèmes thermiques
2 SISKA - Swiss Institute for Speleology and Karstology
3 FAST - Fluides, automatique, systèmes thermiques
4 UFR 919 - Sorbonne Université - UFR d'Ingénierie

Vermiculations are small particle agregates commonly found on cave walls. They are a major concern for the conservation of painted caves, as they can potentially alter valuable parietal prehistoric paintings. We report on laboratory experiments and field observations indicating new tracks for the understanding of physical mechanisms at play in this intricate process. Rheological experiments were performed on cave sediment similar to that of Lascaux cave. We show that this material can undergo a rapid solid-to-liquid transition triggered by variations of the chemical composition of the water film lying on cave walls. Such a transition could be at the origin of vermiculations by allowing the sediment to flow under weak mechanical stress. Furthermore, the implementation of a Geographic Information System of the walls of the Hall of Bulls in Lascaux Cave reveals a weak but non negligible vermiculation activity after the crisis of 2009-2010. In the future, this GIS will enlighten the correlation between vermiculation evolution, humidification phases of the walls, temperature evolutions and chemical monitoring.

Mots clés: painted caves; conservation; vermiculations; Geographic Information System; clay; rheology

Domaines: Héritage culturel et muséologie; Matériaux

Perrine Freydier, Éric Weber, Jérôme Martin, Pierre-Yves Jeannin, Béatrice Guerrier, et al.. Vermiculations in painted caves: new inputs from laboratory experiments and field observations. 2021. ⟨hal-03010557v2⟩