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Regolith map of France

La carte du régolithe de France
François Prognon, Frédéric Lacquement, Caroline Ricordel-Prognon, Florence Quesnel, Pierre Nehlig, Serge Courbouleix, Jean-Pierre Quinquis, Patricia Martin, Damien Rambourg and Patrick Lebret
p. 357-362

Abstracts

Regolith formations are surficial fragmental and unconsolidated rocks whose genesis and properties result from successive periods of surface processes. They comprise:
– autochthonous formations resulting directly from successive periods of surface weathering in the upper 200 metres of the Earth’s crust;
– allochthonous formations in which the unconsolidated deposits result from weathering and transport and have not yet been affected by burial diagenesis.
Regolith studies are currently at the crossroads of new scientific challenges and new environmental needs. Not only do regolith formations support a full spectrum of biological activity, including human activities, they also provide a source of extractable materials and form the substratum of soils. As such, they should be considered as a capital to be managed and protected. Historically, geological maps have focused mainly on substratum geology. Although the inclusion of regolith formations in the 1:50,000-scale geological map series of France since the 1980s has considerably increased our knowledge of France’s regolith, this is still is patchy and generally insufficient for applied uses despite increasing societal pressures demanding up-to-date regolith maps. To produce an updated map at the scale of France is an ambitious project that must necessarily begin with an inventory of existing geological cartographic data relating to regolith formations. A digital two-layered regolith map of France, representing both the allochthonous and autochthonous formations, was produced in 2009 at a scale of 1:1,000,000. Each layer is accompanied by a confidence index map, and a brief descriptive note of the mapped formations (in French) is also available. A critical analysis of the two map layers reveals not only the very uneven nature of our current knowledge in terms of data quantity and quality, but also its deficiency as regards the expectations of the public authorities. Today, therefore, we require surface studies combining geology, geophysics and geochemistry in order to enhance our understanding of the natural processes governing the distribution and evolution of subsoil formations. This approach is critical for developing appropriate guidance in the use and management of natural and groundwater resources. The 2009 map can be viewed and interrogated at http://infoterre.brgm.fr, and a “pdf” of the map and corresponding project report can be downloaded from http://www.brgm.fr/brgm/GEO/rego.htm.

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References

Bibliographical reference

François Prognon, Frédéric Lacquement, Caroline Ricordel-Prognon, Florence Quesnel, Pierre Nehlig, Serge Courbouleix, Jean-Pierre Quinquis, Patricia Martin, Damien Rambourg and Patrick Lebret, « Regolith map of France », Quaternaire, vol. 22/4 | 2011, 357-362.

Electronic reference

François Prognon, Frédéric Lacquement, Caroline Ricordel-Prognon, Florence Quesnel, Pierre Nehlig, Serge Courbouleix, Jean-Pierre Quinquis, Patricia Martin, Damien Rambourg and Patrick Lebret, « Regolith map of France », Quaternaire [Online], vol. 22/4 | 2011, Online since 01 December 2014, connection on 24 November 2017. URL : http://quaternaire.revues.org/6060 ; DOI : 10.4000/quaternaire.6060

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About the authors

François Prognon

BRGM GEO/G2R, BP 36009, F-45060 ORLÉANS cedex. Courriel: f.prognon@brgm.fr

By this author

Frédéric Lacquement

BRGM GEO/G2R, BP 36009, F-45060 ORLÉANS cedex

By this author

Caroline Ricordel-Prognon

BRGM GEO/G2R, BP 36009, F-45060 ORLÉANS cedex

Florence Quesnel

BRGM GEO/G2R, BP 36009, F-45060 ORLÉANS cedex

By this author

Pierre Nehlig

BRGM GEO/G2R, BP 36009, F-45060 ORLÉANS cedex

Serge Courbouleix

BRGM GEO/G2R, BP 36009, F-45060 ORLÉANS cedex

Jean-Pierre Quinquis

BRGM GEO/CAR, BP 36009, F-45060 ORLÉANS cedex.

Patricia Martin

BRGM GEO/CAR, BP 36009, F-45060 ORLÉANS cedex.

Damien Rambourg

BRGM GEO/CAR, BP 36009, F-45060 ORLÉANS cedex.

Patrick Lebret

BRGM REM/ECOM, BP 36009, F-45060 ORLÉANS cedex

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