Offshore bedrock 250K

Key information

1:250 000
UK and adjacent European waters
Free / Licensed
GIS polygon data (ESRI, MapInfo, others available by request)

Free: Available to view as a WMS layer or via the offshore GeoIndex.

Licence: £0.006 per km2. Subject to number of users, licence fee and data preparation fee.

Regional-level use

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Free access

Our free data is available under the Open Government Licence. Please acknowledge reproduced BGS materials.

Sample Download View online (Offshore Geoindex)Web service (OGC WMS)
Supporting documents

The 1:250 000-scale offshore geological maps are available digitally as two themes: offshore bedrock geology and seabed sediments.

The overlying column of sea water imposes major limitations offshore that make it impossible to use normal, onshore, geological mapping techniques. However, other techniques, such as ship-board geophysical surveys, can be used that allow geological interpretations using evidence not normally available onshore.

The offshore bedrock geology theme is essentially the same as that mapped onshore, but it is usually much less detailed. Onshore, a lithostratigraphical nomenclature is used with rocks routinely mapped at formation, member and bed level. Offshore, this is often impossible and rocks are commonly referred to by age. Where it is possible, mapping is usually only to group or formation level at best and even these may not be differentiated into individual units, but shown only as part of a package of units.

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