Conservation of prehistoric caves and stability of their inner climate: Lessons from Chauvet and other French caves

In the last 150years, 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 re...

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Bibliographic Details
Published in:The Science of the total environment 2014-09, Vol.493, p.79-91
Main Authors: Bourges, F., Genthon, P., Genty, D., Lorblanchet, M., Mauduit, E., D'Hulst, D.
Format: Article
Language:English
Subjects:
Cave conservation
Earth Sciences
Earth, ocean, space
Environmental monitoring
Exact sciences and technology
Hydrology
Karst
Marine and continental quaternary
Painted cave
Sciences of the Universe
Surficial geology
Underground confinement
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Summary:In the last 150years, 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 40,000years. 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. •Painted caves present a stable climate due to their inclusion in a karstic system.•Cave stability results from exchanges with outside climate through natural buffers.•Confined cave microclimates are optimal to preserve wall art.•Cave remediation should focus on restoring their initial stable inner climate.
ISSN:0048-9697
1879-1026
DOI:10.1016/j.scitotenv.2014.05.137