GBR BGS Gravity anomalies colour shaded

This low-resolution image has been produced from BGS land and marine gravity data. The colour was generated using the BGS COLMAP software package. Colour levels are defined by histogram equalisation. Combining this image with the grey shaded relief image produces a similar image to the colour shaded relief image. The measured gravity values have been corrected in order to show the anomalies attributable to variations in crustal density. In broad terms the blues are attributable to large volumes of low density rocks, the reds to high density rocks. Significant lows occur, for instance, over areas of thick, low density sedimentary rocks(e.g. Cheshire Basin, Wessex Basin), or large granites (eg Cornwall). For marine data, free-air anomalies have been calculated from observed gravity values along marine survey lines. Line intersection errors between crossing lines and overlapping surveys have been used using network adjustment techniques. Free air anomalies have been calculated for sea-bottom stations. For land data, bouguer anomalies have been calculated from gravity observations at points of known height. In order to minimise the effect of topography, Bouguer corrections for the British Mainland have been applied using a density estimated for each station. Elsewhere a correction density of 2.67 Mg/m3 has been used. Corrections for the gravitational effect of terrain have been made where significant, and in a general extent to a radius of 48.6km. The data have been interpolated onto a 1km x 1km grid using a variable tension technique, and smoothed.

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Date (Revision): 2022-04-08T08:26:24

Status: Completed

Point of contact

Organisation name	Individual name	Electronic mail address	Role
British Geological Survey	Garry Baker	enquiries@bgs.ac.uk	Point of contact

Theme

Geophysics
GeoIndex
Gravity anomalies colour shaded
OneGeology
continent@Europe
subcontinent@Northern Europe
geographicarea@United Kingdom of Great Britain and Northern Ireland
dataprovider@British Geological Survey
serviceprovider@British Geological Survey
DS_TOPIC@geoscientificinformation
DS_DATE@2022
thematic@Geophysics
thematic@Exploration
thematic@Gravimetry

Denominator: 590587.797619

Topic category

Geoscientific information

Reference system identifier: CRS:84

Reference system identifier: EPSG:4326

Reference system identifier: EPSG:4258

Reference system identifier: EPSG:27700

Reference system identifier: EPSG:3857

Distribution format

Name	Version

OnLine resource

Protocol	Linkage	Name
OGC:WMS-1.3.0-http-get-map	https://map.bgs.ac.uk/arcgis/services/GeoIndex_Onshore/geophysics/MapServer/WmsServer?	Gravity.anomalies.colour.shaded
application/xml	https://metadata.bgs.ac.uk/geonetwork/srv/eng/csw?SERVICE=CSW&REQUEST=GetRecordById&ID=9df8df53-2a94-37a8-e044-0003ba9b0d98&elementSetName=full&OutputSchema=http://www.isotc211.org/2005/gmd&version=2.0.2&	Gravity.anomalies.colour.shaded (MetadataURL)
image/png	https://map.bgs.ac.uk/arcgis/services/GeoIndex_Onshore/geophysics/MapServer/WmsServer?request=GetLegendGraphic%26version=1.3.0%26format=image/png%26layer=Gravity.anomalies.colour.shaded	Gravity anomalies (colour shaded) (LegendURL)