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Data sources

sousmonsol makes up no data: it displays and queries the public services of BRGM, Géorisques, Hub’Eau and IGN at the very moment you view them. Every detail sheet cites its source and the date it was accessed; here is the full picture.

French Geological Survey (BRGM)

France’s national geological survey. Its data is served by the map services below (OGC WMS and WFS standards). BRGM website

Terms of reuse: they vary from one dataset to another and are being checked, layer by layer. In the meantime, every piece of information on display carries the credit “Source: BRGM”, the name of the layer and the date it was accessed.

Geology, hydrogeology and gravimetry

https://geoservices.brgm.fr/geologie

  • Geological map at 1:50,000

    The harmonised 1:50,000 geological maps: the nature of the ground at outcrop, sheet by sheet.

    Layer SCAN_H_GEOL50

  • Geological map at 1:250,000

    The regional 1:250,000 geological maps, to read the broad structures.

    Layer SCAN_F_GEOL250

  • Geological map at 1:1,000,000

    The geological map of France at one to a million, an overview of the whole country.

    Layer SCAN_F_GEOL1M

  • Simplified lithology

    The main rock families at 1:1,000,000: chalk, limestones, granites, alluvium…

    Layer LITHO_1M_SIMPLIFIEE, queryable

  • 1:50,000 map sheets

    The index of the 1:50,000 geological maps: number and name of each sheet.

    Layer SCAN_F_GEOL50_CATALOG, queryable

  • Weathered rock thickness

    A model of the thickness of weathered rock, the decomposed rock that covers the bedrock.

    Layer EPAISSEUR_ALTERITES, queryable

  • Water points

    The water point register of the national subsurface database: wells, boreholes, springs.

    Layer BSS_EAU, queryable

  • Infiltration or runoff (IDPR)

    The network development and persistence index: where rainwater soaks in rather than runs off.

    Layer IDPR, queryable

  • Boreholes of the subsurface database

    Declared underground works: boreholes, soundings, wells, with their documents.

    Layer BSS, queryable

  • Gravity stations

    Gravity measurement points, which reveal the density of rocks at depth.

    Layer GRAVI_STATION, queryable

  • Mineral deposits and occurrences

    Recorded deposits, occurrences and indications of mineral substances.

    Layer GITES, queryable

  • Mines

    Mines and their main substances.

    Layer MINES, queryable

  • Naturally occurring asbestos (1:1,000,000)

    How likely asbestos is to be present in natural rocks, at the scale of France.

    Layer AMIANTE_1M, queryable

  • Naturally occurring asbestos (1:50,000)

    How likely naturally occurring asbestos is to be present, mapped at 1:50,000, including the French Antilles and Saint Pierre and Miquelon.

    Layer AMIANTE_50K, queryable

  • Overseas geological maps

    The printed geological maps of Guadeloupe, Saint Martin, Saint Barthélemy, Martinique, French Guiana, Réunion, Mayotte, Saint Pierre and Miquelon, New Caledonia and French Polynesia.

    Layer GEOLOGIE_OUTRE_MER

Natural and industrial hazards

https://geoservices.brgm.fr/risques

  • Rising groundwater

    Areas potentially prone to groundwater overflow or basement flooding, with their reliability.

    Layer REMNAPPE_FR, queryable

  • Shrink-swell clays

    How exposed clay soils are to shrinking and swelling with moisture, a cause of cracks in buildings.

    Layer ALEARG, queryable

  • Underground cavities

    Recorded abandoned cavities of non-mining origin: quarries, cellars, marl pits, civil works.

    Layer CAVITE_LOCALISEE, queryable

  • Ground movements

    Recorded landslides, rockfalls, mudflows, collapses and bank erosion.

    Layer MVT_LOCALISE, queryable

  • Historical earthquakes

    Epicentres from the SisFrance database, with the observed intensity, in mainland France and overseas.

    Layer SIS, queryable

  • Seismic intensity by commune

    The maximum intensity possibly felt in each commune, interpolated from historical earthquakes.

    Layer SIS_INTENSITE, queryable

  • Faults and recent deformation

    Faults and evidence of recent deformation or palaeo-earthquakes from the Néopal database.

    Layer NEOPAL_FAILLE, queryable

Materials observatory

https://geoservices.brgm.fr/odmgm

  • Active quarries

    Working extraction sites, as points and outlines.

    Layer EXPLOIT_ACTIVE, queryable

  • Closed quarries

    Former extraction sites, as points and outlines.

    Layer EXPLOIT_FERMEE, queryable

ADES, groundwater data portal

https://mapsref.brgm.fr/wxs/ades/public

  • Groundwater monitoring wells (ADES)

    The stations where groundwater levels are measured, published by the ADES portal; their readings can be seen in each station’s sheet, from Hub’Eau, and on ades.eaufrance.fr.

    Layer point_eau_piezo, queryable

The scanned documents of boreholes (logs, reports, plans) are read on demand from each borehole’s sheet on the InfoTerre portal, which publishes no reuse licence: the site shows their thumbnails and pages, converted to PNG, with a link to the original sheet, and caches the list for one day at most. BRGM points out that these documents, submitted by third parties under the French Mining Code, are neither exhaustive nor guaranteed to be accurate. The validated log of a borehole with verified geology is an image drawn by BRGM’s log service, relayed as is and cached for one week at most. Beneath each point, the sheet shows the geological log of the nearest described borehole: the borehole WFS tells which ones have a log, and the list of its layers is read from its InfoTerre sheet, cached for one day at most.

Hub’Eau

The public water data API, run by the French Biodiversity Agency (OFB) and BRGM, supplies on demand the measured groundwater levels and the latest nitrate and pesticide analyses of a borehole, taken from the national ADES database. The browser calls it directly. This data is published under the Etalab Open Licence. Hub’Eau website

French National Institute of Geographic and Forest Information (IGN)

The basemaps and the address search come from the IGN Géoplateforme, under the Etalab Open Licence 2.0.

  • Grey map

    Source: Plan IGN

  • IGN map

    Source: Plan IGN

  • Aerial photographs

    Source: BD ORTHO

  • Address and place search

    Géoplateforme geocoding service (Base adresse nationale and IGN reference datasets).

Géorisques

The French government’s risk portal, published by the ministry responsible for the ecological transition. The map shows its polluted soils, radon potential, seismic zoning, flooding and pipelines, through the map server below, hosted by BRGM. Each commune page reads from it the recorded risks (GASPAR database), natural disaster declarations, seismic zoning, radon potential, the number of cavities and ground movements recorded by BRGM, and risk prevention plans. This data is published under the Etalab Open Licence 2.0. Géorisques website

Natural and technological hazard maps

https://mapsref.brgm.fr/wxs/georisques/risques

  • Regulatory seismic zoning

    The seismic zone of each commune, from 1 (very low) to 5 (high), which sets the earthquake-resistant building rules.

    Layer risq_zonage_sismique, queryable

  • Radon potential

    The radon potential category of each commune, based on the uranium content of the rocks: low, low with aggravating factors, or significant.

    Layer RADON_COMMUNE, queryable

  • Soil information sectors

    Land where the State knows that soil pollution requires a study before building or changing its use.

    Layer SSP_CLASSIFICATION_SIS, queryable

  • Polluted sites (former BASOL)

    Polluted or potentially polluted sites that call for action by the public authorities, to prevent or to remedy.

    Layer SSP_INSTRUCTION, queryable

  • Former industrial sites (CASIAS)

    The historical inventory of former industrial sites and service activities, whose soil may have been polluted.

    Layer SSP_ETABLISSEMENT, queryable

  • Flood risk prevention plans

    The boundaries of flood risk prevention plans (PPRI) and, close up, their zoning: where building is forbidden or subject to requirements.

    Layer PPRN_INOND, queryable

  • Areas prone to river flooding

    The approximate envelope of potential flooding (EAIP) from river overflow and runoff, drawn up for the EU Floods Directive.

    Layer EAIP_CE, queryable

  • Areas prone to coastal flooding

    The approximate envelope of potential flooding (EAIP) from the sea, along the coast.

    Layer EAIP_SM, queryable

  • Hazardous material pipelines

    Pipelines carrying natural gas, hydrocarbons and chemicals, which the service does not show at scales larger than 1:20,000.

    Layer CANALISATIONS, queryable

The list of communes, their populations and the position of their town halls come from Insee’s official geographic code, through the Découpage administratif API (geo.api.gouv.fr).

Freshness and limits

The maps are requested from the services each time they are displayed: they reflect their latest update. Queries about a point are cached for one day at most; Géorisques responses, for one week at most. This data describes the state of knowledge at a given scale: it does not replace a ground investigation or regulatory documents.