GeoIndex help | Offshore map theme

View the offshore GeoIndex

Click on the links below for further information about the available datasets.

Overview

The Offshore Geoindex shows the range of Marine Geoscience Data held by the British Geological Survey (BGS) within the National Geoscience Data Centre (NGDC). This is primarily shallow geology and geophysics data collected as either part of regional and local mapping work or provided to BGS by third-parties.

In addition to viewing the data distribution, you can query the data, make selections and export. The sample data and related information are now available under the Open Government Licence (OGL), which states that the data may be used freely, subject to appropriate acknowledgement, which is described within the data download.

GeoIndex datasets are also available to view as a Web Map Service (WMS)

These data underpin the ongoing work of BGS to create interpreted outputs, more details of which can be seen on Our Products page.

BGS Offshore Marine Information Products are also available to view as a WMS

These data provide the foundations for the Marine Environmental Mapping Programme (MAREMAP) outputs shown on the MAREMAP Portal

The Marine Data at the BGS page provides more information on geological, geophysical and environmental data on the seabed and sub-seabed.

The Marine Operations and Engineering page provides more information on sampling and geophysical survey equipment.

Sample Data

This is a group layer that contains information and data for offshore sampling activities. The Activity Data layer contains only location information and metadata, whereas the Geochemical, Geological, Geotechnical and Seabed Sample Data layers include observations and/or measurements.

Sampling activities include boreholes, shallow cores, seabed grabs and dredges. There may be several activities carried out at a single location. Samples are uniquely named using a degree square, a number within the square, an equipment code and equipment attempt number. An example would be +54-003/1201/VE/2 – this is the 2nd Vibrocore at survey station 1201 within degree square 54° to 55°N and 2° to 3°W.

View a gallery of example marine sample/borehole records.

Activity Data

This layer shows the location and basic information for offshore sampling activities. It contains information about the activities which are conducted at a location resulting in the collection of data and/or physical material. Links to scanned images of sample description sheets, core and borehole logs are provided for BGS and Rockall Consortium samples only (where available).

View Activity Data attribute descriptions.

View the NGDC Material Collection for more information on physical material collected at survey locations.

Geochemical Data

This layer provides geochemical analysis associated with offshore sampling activities. It contains analysis of 38 elements and should be used as a baseline for chemical element concentrations in seabed sediments, against which samples collected in the future may be assessed.

View Geochemical Data attribute descriptions.

View report, The geochemistry of sea-bed sediments of the United Kingdom Continental Shelf: the North Sea, Hebrides and West Shetland shelves, and the Malin-Hebrides sea area for more information.

Geological Data

This layer provides geological descriptions associated with offshore sampling activities. It contains a variety of geoscientific observations; these include rock/sediment classification, grain size, sorting, sphericity, roundness, hardness, plasticity, presence of flora or fauna, colour, chronostratigraphy and lithostratigraphy. Note that this layer contains data at depth.

View Geological Data attribute descriptions.

Geotechnical Data

This layer provides geotechnical readings associated with offshore sampling activities. It contains a variety of types of geotechnical measurements; these include shear and compressive strength. Expert advice may be required in the use of these data. Note that this layer contains data at depth.

View Geotechnical Data attribute descriptions.

Seabed Sediment Data

This layer provides particle size analysis associated with offshore sampling activities. It contains a variety of types of particle size analysis; these include folk analysis, gravel, sand and mud percentages, phi and half-phi sand analysis and carbonate analysis based on gravel, sand and mud fractions. Note these data are primarily from the seabed, but contain some data at depth.

View Seabed Sediment Data attribute descriptions.

Shallow Geophysics Data

This layer shows the location and basic information for marine geophysical survey lines. Geophysical surveys include shallow seismic reflection (e.g. airgun, boomer, pinger, sparker and water gun) and sonar (e.g. echo sounder, sidescan sonar and transit sonar). There may be several equipments deployed on a single survey line. Survey Lines are uniquely named as survey and line identifier (name or number). An example would be BGS1985_6-16 – this is line 16 of survey BGS1985/6.

Images of scanned records for the majority of surveys are available on request.

Department of Energy and Climate Change (DECC)

Offshore Hydrocarbon Wells

The UK Continental Shelf (offshore) hydrocarbon well collection contains material from approximately 8000 wells, including over 300 km of drillcore and 4.5 million samples of cuttings. During 2011–12, the collection was transferred from Gilmerton to Keyworth. Transferred core has been photographed, links to these images are provided (where available).

You can also use a form to search this database using the Offshore Hydrocarbon Wells search page.

Marine Environment Data and Information Network (MEDIN)

Oil and Gas Industry Site Surveys

The Marine Environment Data and Information Network (MEDIN) is a partnership of UK organisations committed to improving access to marine data and easier data sharing. BGS is the accredited Data Archive Centre (DAC) for Geology, Geophysics and Backscatter.

As part of the BGS MEDIN DAC, we hold information about oil and gas industry site surveys. This layer shows the geographic location of the underlying data together with the contact details of the data holders. For further information contact the custodian of the data.

More details at the MEDIN Oil and Gas Industry Site Survey Project.

Magnetic Anomaly Maps

These low-resolution images have been produced from BGS airborne and marine magnetic data. The colour was generated using the BGS COLMAP software package. Colour levels are defined by histogram equalisation. Combining the magnetic anomaly image with the grey shaded relief image produces a colour shaded relief image.

A published coloured shaded relief map, using the full resolution of the data and produced at a scale of 1:1 500 000, is available. The map covers a larger area than this image, and includes additional data from other sources.

The data used to compile this image are available in various forms for academic and commercial licencing.

DATA PROCESSING

The data from surveys covering the UK mainland have been digitised from their original analogue form. Elsewhere data were acquired digitally. Standard methods of processing were used to remove diurnal and secular variations and to minimise line intersection errors. While efforts have been made to remove artefacts from the data, some may remain between adjacent datasets. Generally anomalies over man–made structures have not been removed.

The data have been interpolated onto a 1km x 1km grid using a variable tension technique, and smoothed.

REFERENCE FIELDS

Total field magnetic anomalies are referred to a variant of the International Geomagnetic Reference Field 1990 (IGRF90). In order to achieve an acceptable fit between adjacent surveys a correction was applied to IGRF90 for epochs prior to 1970, taking account magnetic observatory values.

Gravity Anomaly Maps

These low-resolution images have 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 the gravity anomaly image with the grey shaded relief image produces a colour shaded relief image.

A published coloured shaded relief map, using the full resolution of the data and produced at a scale of 1:1 500 000, is available. The map covers a larger area than this image, and includes additional data from other sources.

The data used to compile this image are available in various forms for academic and commercial licencing.

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 (e.g. Cornwall).

BGS provide two commercial services for accurately determining site specific values of g usually used by engineering laboratories doing weight drop tests etc. where an accurate value of gravity is required. For less accurate applications a value can also be calculated.

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.

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.

Cultural Data

Blocks

A quadrant is divided into 30 blocks measuring 12 minutes of longitude by 10 minutes of latitude identified by a number.

Lat-Long

Latitude-Longitude grid (1 degree).

Median Lines

Agreed boundaries between international offshore designated areas.

Quadrants

An area enclosed by one degree of latitude and longitude and identified by a number. Blocks are a subdivision of a quadrant.

Attribute Descriptions

More detailed attribute descriptions for certain layers within the Offshore GeoIndex.

Bathymetry DAC

UK Hydrographic Office INSPIRE Portal and MEDIN Bathymetry Data Archive Centre.

BGS Marine Geoscience

Information on areas of research and operations.

EDINA

EDINA delivers online services and tools to benefit students, teachers and researchers in UK Higher and Further Education and beyond.

BGS products are available through Digimap.

Oil and Gas: Offshore Maps and GIS Shapefiles

Access to digital maps and GIS shapefiles of current UKCS data.

Strategic Environmental Assessment (SEA) Data Portal

Free access to available information, data and reports which have been produced through the UK Department of Energy and Climate Change SEA process.

UKOilandGasData

UKOilandGasData is an online resource storing metadata about UKCS offshore oil and gas wells, 2D and 3D seismic surveys, infrastructure, licences and fields. The metadata may be accessed, searched and displayed in either a table format or on the interactive map and is FREE to view on UKOilandGasData.