title: Conservation of prehistoric caves and stability of their inner climate: lessons from Chauvet and other French caves.
abstract: In the last 150 years, some prehistoric painted caves suffered irreversible degradations due to misperception of conservation issues and subsequent mismanagement. These sites presented naturally an exceptional stability of their internal climate allowing conservation in situ of outstanding fragile remains, some for nearly 40,000 years. This is for a large part due to exchanges of air, CO2, heat and water with the karstic system in which these caves are included. We introduce the concept of underground confinement, based on the stability of the inner cave climate parameters, especially its temperature. Confined caves present the best conservative properties. It is emphasized that this confined state implies slow exchanges with the surrounding karst and that a stable cave cannot be viewed as a closed system. This is illustrated on four case studies of French caves of various confinement states evidenced by long term continuous monitoring and on strategies to improve their conservation properties. The Chauvet cave presents optimal conservation properties. It is wholly confined as shown by the stability of its internal parameters since its discovery in 1994. In Marsoulas cave, archeological works removed the entrance scree and let a strong opening situation of the decorated zone. Remediation is expected by adding a buffer structure at the entrance. In Pech Merle tourist cave, recurrent painting fading was related to natural seasonal drying of walls. Improvement of the cave closure system restored a confined state insuring optimal visibility of the paintings. In Gargas tourist cave, optimization of closures, lighting system and number of visitors, allowed it to gradually reach a semi-confined state that improved the conservation properties. Conclusions are drawn on the characterization of confinement state of caves and on the ways to improve their conservation properties by restoring their initial regulation mechanisms and to avoid threats to their stability.
authors.affiliation: GEconseil, 30 rue de la République, 09200 St Girons, France. Electronic address: geconseil@wanadoo.fr.
authors.forename: F
authors.initials: F
authors.lastname: Bourges
authors.affiliation: IRD/HSM, Univ. Montpellier II, Case MSE, 34095 Montpellier, France. Electronic address: pierre.genthon@ird.fr.
authors.forename: P
authors.initials: P
authors.lastname: Genthon
authors.affiliation: LSCE, UMR CEA/CNRS 8212, L'Orme des Merisiers CEA Saclay, 91191 Gif/Yvette cedex, France. Electronic address: dominique.genty@lsce.ipsl.fr.
authors.forename: D
authors.initials: D
authors.lastname: Genty
authors.affiliation: Directeur de recherche honoraire au CNRS, Roc des Monges, 46200 Saint-Sozy, France. Electronic address: michel.lorblanchet@wanadoo.fr.
authors.forename: M
authors.initials: M
authors.lastname: Lorblanchet
authors.affiliation: Service Régional de l'Archéologie, Direction Régionale des Affaires Culturelles de Midi-Pyrénées 32, rue de la Dalbade, 31080 Toulouse, France.
authors.forename: E
authors.initials: E
authors.lastname: Mauduit
authors.affiliation: GEconseil, 30 rue de la République, 09200 St Girons, France. Electronic address: eric.mauduit@culture.gouv.fr.
authors.forename: D
authors.initials: D
authors.lastname: D'Hulst
keywords: Cave conservation; Environmental monitoring; Karst; Painted cave; Underground confinement