An agreement has been signed between the public establishment responsible for the restoration of Notre-Dame de Paris and the Bureau of Geological and Mining Research (BRGM), in order to select the freestone that will replace those many damaged by the 2019 fire. .
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These stones, which must be "
aesthetically and physically compatible
" with the architectural ensemble formed by the cathedral, will have to be found "
in significant quantities
", a statement said on Wednesday.
The public establishment and the BRGM, an organization acting as a national geological service, have defined a research and development program, approved on Wednesday by the Council of Ministers, for the identification and selection of these new stones.
The methodology provides for geological investigations in quarries and laboratory tests on samples.
The program involves the Historical Monuments Research Laboratory (LRMH) of the Ministry of Culture.
Complex sedimentation process
The original stones had been extracted in the 12th-13th centuries from the subsoil of Paris: they were limestone rocks from a geological layer formed 41 to 48 million years ago.
Such deposits emerge in many sectors of the Paris basin.
They are still exploited today for the supply of stones, in about ten quarries in the Oise and Aisne.
These limestones are the result of a complex sedimentation process, which the program plans to study in order to identify their characteristics.
Scheduled to end in mid-2021, this program will focus primarily on active quarries, then unexploited deposits if necessary.
The public establishment, directed by Jean-Louis Georgelin, is starting this year the phase of restoration of the jewel of Gothic art which must be completed in April 2024. Among other missions, it has the promotion of the know-how which contributes to the site. .
The exact knowledge of the materials used in the Middle Ages - wood, stones, etc. - is essential to ensure an identical reconstruction in the best conditions.
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In November, the government presented an ordinance facilitating the reopening or extension of new quarries where necessary.
This should "
considerably facilitate the restoration work of Notre-Dame
", which has "
a significant need for freestone
", he indicated.
