Map based index (GeoIndex) gravity anomalies
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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Citation proposal
British Geological Survey. Map based index (GeoIndex) gravity anomalies. https://services.mspdata.eu:/geonetwork/srv/api/records/9df8df53-2a94-37a8-e044-0003ba9b0d98 |
Simple
- Date ( Creation )
- 2000
Custodian
British Geological Survey
The Lyell Centre, Research Avenue South
EDINBURGH
LOTHIAN
EH14 4AP
United Kingdom
Originator
British Geological Survey
Environmental Science Centre,Keyworth
NOTTINGHAM
NOTTINGHAMSHIRE
NG12 5GG
United Kingdom
Distributor
British Geological Survey
Environmental Science Centre,Keyworth
NOTTINGHAM
NOTTINGHAMSHIRE
NG12 5GG
United Kingdom
- Maintenance and update frequency
- asNeeded As needed
- GEMET - INSPIRE themes
-
- Geology
- BGS Thesaurus of Geosciences
-
- Geophysics , Gravity anomalies , Gravity values
- Keywords
-
- NERC_DDC
- Use limitation
- Either: (i) the dataset is made freely available, e.g. via the Internet, for a restricted category of use (e.g. educational use only); or (ii) the dataset has not been formally approved by BGS for access and use by external clients under licence, but its use may be permitted under alternative formal arrangements; or (iii) the dataset contains 3rd party data or information obtained by BGS under terms and conditions that must be consulted in order to determine the permitted usage of the dataset. Refer to the BGS staff member responsible for the creation of the dataset if further advice is required. He / she should be familiar with the composition of the dataset, particularly with regard to 3rd party IPR contained in it, and any resultant use restrictions. This staff member should revert to the IPR Section (ipr@bgs.ac.uk ) for advice, should the position not be clear.
- Access constraints
- otherRestrictions Other restrictions
- Other constraints
- otherRestrictions
- Denominator
- 250000
- Metadata language
- English English
- Topic category
-
- Geoscientific information
- Geographic identifier
-
GBN
- Date ( Revision )
- 2009
- Geographic identifier
-
GREAT BRITAIN [id=139600]
- Date ( Creation )
- 1979
N
S
E
W
))
- Supplemental Information
- Data is visible at map scales above 1:250 000 scale.
- Reference system identifier
-
OGP
/
urn:ogc:def:crs:EPSG::27700
- Date ( Revision )
- 2005
- Distribution format
-
- Unknown (Unknown )
Distributor
British Geological Survey
Environmental Science Centre,Keyworth
NOTTINGHAM
NOTTINGHAMSHIRE
NG12 5GG
United Kingdom
- OnLine resource
- Gravity anomalies
- OnLine resource
-
Geophysics map theme
The wms layer for 'GeoIndex gravity anomalies' is held within the 'Geophysics' theme WMS layer which this URL connects to.
- OnLine resource
-
Geophysics map theme
The user will need to select 'Map layers' from the top left menu and select the 'Gravity anomalies' check box from the drop down menu to view the data.
- Hierarchy level
- dataset Dataset
- Other
- dataset
Conformance result
- Date ( Publication )
- 2011
- Explanation
- See the referenced specification
- Pass
- false
Conformance result
- Date ( Publication )
- 2010-12-08
- Explanation
- See http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2010:323:0011:0102:EN:PDF
- Pass
- false
- Statement
- 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. Line intersection errors between crossing lines and overlapping surveys have been dealt with 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.
Metadata
- File identifier
- 9df8df53-2a94-37a8-e044-0003ba9b0d98 XML
- Metadata language
- English English
- Hierarchy level
- dataset Dataset
- Date stamp
- 2017-01-17
- Metadata standard name
- NERC profile of ISO19115:2003
- Metadata standard version
- 1.0
Point of contact
British Geological Survey
-
Royles,Christopher P
(NERC-BGS Geophysicist )
Environmental Science Centre,Keyworth
NOTTINGHAM
NOTTINGHAMSHIRE
NG12 5GG
United Kingdom
- Dataset URI
- http://data.bgs.ac.uk/id/dataHolding/13605466