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 survey information (sample and geophysical 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 Web Map Service (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.

Sampling Activity: Overview & Scanned Records

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 (where available) for openly available sampling activities where terms of use are known.

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.

Geophysical Data

This is a group layer that contains information and data for offshore 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 1985/6#16 – this is line 16 of survey 1985/6.

View a gallery of marine geophysical records.

Shot points

This layer shows the location of offshore geophysical survey line shot points. It contains details of all shot points for a survey line.

View geophysical survey line shot point attribute descriptions.

Survey Lines: Overview & Scanned Records

This is a group layer that contains the location and basic information for offshore geophysical survey lines. It contains the start and end points of each survey line together with information about the equipment types used. Links to scanned images of geophysical records are provided (where available) for openly available survey lines where terms of use are known.

The Seismic Reflection layer includes sub seabed imaging which provides information about structures below the seabed.

The Sonar layer includes seabed imaging which provides bathymetric (depth) data or information about the roughness of the seabed.

View geophysical survey line attribute descriptions.

Survey Data

This is a layer that shows the location and basic information for coastal and marine surveys which result in the collection of data. It includes information about the survey, including the types of equipment deployed during the survey.

View coastal and marine survey data attribute descriptions.

Oil and Gas Authority (OGA)

Offshore Hydrocarbon Wells

The United Kingdom Continental Shelf (UKCS) offshore hydrocarbon well borehole materials collection contains material from approximately 8000 wells, including over 300km 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.

BGS Offshore Marine Products

The 1:250 000 scale offshore geological maps in the UTM series (Universal Transverse Mercator projection) are available digitally as four layers: bedrock geology (linear and polygon features - DigRock250), hard substrate (DigHardSubstrate250) and sea-bed sediments (DigSBS250).

Find out more about BGS offshore marine information products.

BGS Hard Substrate (250k)

Hard substrate is defined as cobbles, boulders and rock recorded at, or within 0.5 m of the sea-bed. These textural classes are defined in accordance with the Wentworth scale, where particles with a diameter > 64mm (cobble) are considered in the interpretation. The definition includes sediment veneer overlying hard substrate in some areas. This is used in order to include both infaunal and epifaunal communities and is considered beneficial for habitat mappers.

This dataset is produced for use at 1:250,000 scale. This scale data should not be relied on for local or site-specific geology, or navigation. This is a view only service, however the full product is available for licencing.

Contact Digital Data for more information on licencing DigHardSubstrate250.

BGS Seabed Sediment (250k)

DigSBS250 is a digital map showing the distribution of sea-bed sediment types in the UK Continental Shelf (UKCS) area. Sea–bed sediments are mapped offshore, where the most recent deposits commonly form a veneer or superficial layer of unconsolidated material on the seabed. Their distribution and composition is determined using a range of remotely sensed and physical ground truthing data.

The sediment divisions on the map are primarily based on particle size analysis (PSA) of both surface sediment samples and the uppermost sediments taken from shallow cores. Sediments are classified according to the modified Folk triangle classification (Folk, 1954, Journal of Geology, Vol. 62, pp 344–359). The modified Folk diagram and classification used by BGS differs from that created by Folk (1954) in that the boundary between "no gravel" and "slightly gravelly" is changed from trace (0.05<) to 1<) weight of particles coarser than –1Ø (2mm), shown below. The boundaries between sediment classifications or types are delineated using sample station particle size analyses and descriptions, seafloor topography derived from shallow geophysical and, where available, multibeam bathymetry, backscatter and side scan sonar profiles.

This dataset is produced for use at 1:250,000 scale. This scale data should not be relied on for local or site-specific geology, or navigation. This is a view only service, however the full product is available for licencing.

Contact Digital Data for more information on licencing DigSBS250.

BGS Linear Bedrock (250k)

This is in the linear layer (including faults, folds and other linear features) of the DigRock250k dataset, which is a digital geological map showing the distribution of bedrock types in the UK Continental Shelf (UKCS) area, and representing the natural continuation of the onshore bedrock geology into the offshore. The bedrock geology below the sea-bed is of importance to a range of groups, including marine habitat mappers, marine spatial planners, the offshore construction and development sector, and the dredging and aggregate industries.

The bedrock divisions on the DigRock250k map represent the principal lithostratigraphical units (e.g. formations and groups) in the UK, ranging in age from Proterozoic to Cainozoic, as defined in the BGS Lexicon of Named Rock Units.

The offshore bedrock geology was mapped using a range of remotely sensed (e.g. seismic, bathymetry) and physical ground truthing data (e.g. rock drills, cores).

This dataset is produced for use at 1:250,000 scale. This scale data should not be relied on for local or site-specific geology, or navigation. This is a view only service, however the full product is available for licencing.

Contact Digital Data for more information on licencing DigRock250.

BGS Bedrock (250k)

This is in the polygon layer of the DigRock250k dataset, which is a digital geological map showing the distribution of bedrock types in the UK Continental Shelf (UKCS) area, and representing the natural continuation of the onshore bedrock geology into the offshore. The bedrock geology below the sea-bed is of importance to a range of groups, including marine habitat mappers, marine spatial planners, the offshore construction and development sector, and the dredging and aggregate industries.

The bedrock divisions on the DigRock250k map represent the principal lithostratigraphical units (e.g. formations and groups) in the UK, ranging in age from Proterozoic to Cainozoic, as defined in the BGS Lexicon of Named Rock Units.

The offshore bedrock geology was mapped using a range of remotely sensed (e.g. seismic, bathymetry) and physical ground truthing data (e.g. rock drills, cores).

This dataset is produced for use at 1:250,000 scale. This scale data should not be relied on for local or site-specific geology, or navigation. This is a view only service, however the full product is available for licencing.

Contact Digital Data for more information on licencing DigRock250.

BGS Geological Factor Maps

A series of maps describing geological factors relevant to offshore seabed activities. Produced in collaboration with The Crown Estate in 2014.

BGS Quaternary Deposits Thickness

The Quaternary Deposits Thickness dataset is a digital geological map across the bulk of the UK Continental Shelf (UKCS), for areas up to a water depth of 200m, which shows the thickness of the deposits over bedrock in three categories: <5m, 5-50m, and >50m Quaternary cover. These depth bands were picked because they represent the horizons that have impact on offshore infrastructure deployment. The map is derived from (unpublished) BGS 1:1,000,000 scale Quaternary digital geological mapping.

The map was produced in 2014 in collaboration with The Crown Estate as part of a project to assess seabed development opportunities across the UKCS.

This map has been released for viewing on the Offshore GeoIndex alongside a series of other offshore geological maps from the BGS

BGS Quaternary Deposits Summary Lithologies

The Quaternary Deposits Summary Lithologies dataset is an offshore digital geological map across the bulk of the UK Continental Shelf (UKCS), for areas up to a water depth of 200 m, which groups the deposits into classes based on similar engineering geology characteristics. The map is derived from (unpublished) BGS 1:1,000,000 scale Quaternary digital geological mapping.

The map was produced in 2014 in collaboration with The Crown Estate as part of a project to assess seabed development opportunities across the UKCS.

This map has been released for viewing on the Offshore GeoIndex alongside a series of other offshore geological maps from the BGS.

BGS Bedrock Summary Lithologies

The Bedrock Summary Lithologies dataset is digital geological map across the bulk of the UK Continental Shelf (UKCS), for areas up to a water depth of 200m, which groups the bedrock lithologies (rock types) into classes based on similar engineering geology characteristics. The map is derived from the 1:250,000 scale digital bedrock map of the UKCS, called DiGRock250k, which is available separately from the BGS.

The map was produced in 2014 in collaboration with The Crown Estate as part of a project to assess seabed development opportunities across the UKCS.

This map has been released for viewing on the Offshore GeoIndex alongside a series of other offshore geological maps from the BGS.

Cultural Data

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.

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).

BGS Marine Geoscience

Information on marine geoscience areas of research and operations.

Oil and Gas Authority Data

Access to digital maps and GIS shapefiles of the UKCS.

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.

Strategic Environmental Assessment (SEA) Data Portal

Free access to available information, data and reports which have been produced through the UK Department for Business, Energy & Industrial Strategy SEA process.

Bathymetric DAC

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

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.