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 BGS within the National Geoscience Data Centre (NGDC). These are primarily shallow geology and geophysics data collected as either part of regional or local mapping work, or provided to the BGS by third parties. The BGS is the Marine Environment Data and Information Network (MEDIN) data archive centre (DAC) for geology, geophysics and backscatter.

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

These data underpin the ongoing work of BGS to create interpreted outputs, more details of which can be seen on our products. They also provide the foundations for the Marine Environmental Mapping Programme (MAREMAP) outputs shown on the MAREMAP portal.

GeoIndex datasets are also available to view as a web map service (WMS) as are offshore marine information products.

The marine data at the BGS page provides more information on geological, geophysical and environmental data on and beneath the sea bed. The marine operations and engineering page provides more information on sampling and geophysical survey equipment.

For more information please contact marine enquiries.

Survey overview

The survey overview layer shows the location and basic information for coastal and marine surveys that result in the collection of data. It includes information about the survey, including the types of equipment deployed during the survey. For some surveys, a zip file of additional data can be downloaded using the URL link provided.

View coastal and marine survey data attribute descriptions.

Sample data

This is a group layer containing information and data for offshore sampling activities. The activity and scan layer contains location information, metadata and links to scanned sample datasheets/core logs, whereas the geological, geotechnical, geochemical and sea-bed sediment data layers include observations and/or measurements as digital values. Equipment-specific layers are available for activity and scan, geology data, and geotechnical data.

Sampling activities include boreholes, shallow cores, sea bed 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 indicates the second Vibrocore at survey station 1201 within degree square 54° to 55°N and 2° to 3°W.

View a gallery of marine sample/borehole records.

Activity and scan

These layers show the location and basic information for offshore sampling activities. There is a layer for all equipment as well as equipment-specific layers. They contain information about the activities conducted at a location that result 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 sampling activity attribute descriptions.

Geological data

These layers provide geological descriptions associated with offshore sampling activities. There is a layer for all equipment as well as equipment-specific layers. They contain a variety of geoscientific observations, including:

  • rock/sediment classification
  • grain size
  • sorting
  • sphericity
  • roundness
  • hardness
  • plasticity
  • presence of flora or fauna
  • colour
  • chronostratigraphy
  • lithostratigraphy

Note that this layer contains data at depth.

View geological data attribute descriptions.

Geotechnical data

These layers provide geotechnical readings associated with offshore sampling activities.There is a layer for all equipment as well as equipment-specific layers. They contain a variety of types of geotechnical measurements including 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.

Geochemical data

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

View geochemical data attribute descriptions.

See our 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.

Sea-bed sediment data

This layer provides particle size analysis associated with offshore sampling activities. It contains a variety of types of particle size analyses these including:

  • Folk analysis
  • gravel, sand and mud percentages
  • phi and half-phi sand analysis
  • carbonate analysis based on gravel, sand and mud fractions

Note these data are primarily from the sea bed, but contain some data at depth.

BGS data input methodologies used in the past between northern and southern parts of BGS vary. The underlying phi data values are sound except where human error may have occurred. Where the sand phi weight analysed was a split or fraction of the total sand component of the sample, the northern and southern parts of the BGS adopted differing data-recording methods. The northern part of the BGS generally recorded the sand phi weight for each phi interval for the actual volume of sample analysed. The southern part of the BGS generally took the sand phi weight for each phi interval, then calculated the percentage of each phi sand interval and used these values to back calculate the phi sand weight representative of the total sand, which was then recorded in the database.

View sea-bed sediment data attribute descriptions.

Geophysical lines and scans

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, side-scan sonar and transit sonar). There may be several pieces of equipment 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.

The group includes seismic reflection, sonar and shot-point layers.

Seismic reflection

This layer shows the location of geophysical survey lines, including sub-sea bed imaging that provides information about structures below the sea bed and start/end-of-line coordinates.

View geophysical survey line attribute descriptions and a gallery of marine geophysical records.

Sonar

This layer shows the location of sonar survey lines, including sea bed imaging that provides information about the roughness of the sea bed or simple bathymetric (depth) data, and start/end-of-line coordinates. Links to scanned images of sonar records are provided (where available) for openly available survey lines where terms of use are known.

View geophysical survey line attribute descriptions and 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.

Backscatter

This is a group layer that contains information and data for backscatter.

Backscatter polygons and data

This layer shows the location and basic information for bathymetric surveys containing backscatter data. A zip file of the backscatter image files (e.g. geotiffs) for the survey can be downloaded using the URL link provided. For access to the data underlying the images please contact marine enquiries. Note that there can be more than one polygon per survey and these will link to the same zip file for the entire survey. The majority of the data were collected and processed for the Maritime and Coastguard Agency (MCA) under the Civil Hydrography Programme. If further processing is required, the BGS can provide a quote.

To download the related bathymetry data go to the UKHO portal.

Backscatter image

This layer shows the location and image of backscatter data. Note that the image layer is a lower-quality overview. The image data are available for download via the backscatter polygon and data layer. The majority of the data were collected and processed for the Maritime and Coastguard Agency (MCA) under the Civil Hydrography Programme. If further processing is required, the BGS can provide a quote.

To view the related bathymetry data go to the UKHO portal.

Oil and Gas Authority (OGA)

Offshore hydrocarbon wells

This layer shows hydrocarbon wells. Various offshore maps and GIS shapefiles are available from the OGA.

The United Kingdom Continental Shelf (UKCS) offshore hydrocarbon well borehole materials 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 and links to these images are provided where available.

You can also use a form to search the offshore hydrocarbon wells database.

Oil and gas industry site surveys

MEDIN is a partnership of UK organisations committed to improving access to marine data and easier data sharing. The 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 are available 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 colour-shaded relief map, using the full resolution of the data and produced at a scale of 1:1 000 000, 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 artificial structures have not been removed.

The data have been interpolated onto a 1 km × 1 km 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 colour-shaded relief map, using the full resolution of the data and produced at a scale of 1:1 000 000, 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 and 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).

The BGS provide two commercial services for accurately determining site-specific values of gravity usually used by engineering laboratories doing, for example, weight drop tests, 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 48.6 km.

The data have been interpolated onto a 1 km × 1 km 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:

Find out more about BGS offshore marine information products.

BGS hard substrate (250k)

Hard substrate is defined as cobbles, boulders or 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 greater than 64 mm (cobbles) 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 sea-bed sediment (250k)

BGS Geology: marine sediments 250k is a digital map showing the distribution of sea-bed sediment types in the 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.

Modified Folk diagram.

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 the BGS differs from that created by Folk (1954) in that the boundary between "no gravel" and "slightly gravelly" is changed from "trace" or less than 0.05 percent weight of particles coarser than –1Ø (2 mm) to one per cent, as shown in Figure 1. The boundaries between sediment classifications or types are delineated using sample-station particle-size analyses and descriptions, sea-floor 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 BGS Geology: marine sediments 250k.

BGS linear bedrock (250k)

This is in the linear layer (including faults, folds and other linear features) of the BGS Geology: marine bedrock 250k dataset, which is a digital geological map showing the distribution of bedrock types in the UKCS area, 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 Cenozoic, 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 BGS Geology: marine bedrock 250k.

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 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 Cenozoic, 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 BGS Geology: marine bedrock 250k.

BGS geological factor maps

This is a series of maps describing geological factors relevant to offshore sea-bed activities. The maps were produced in 2014 in collaboration with The Crown Estate as part of a project to assess seabed development opportunities across the UKCS and have been released for viewing on the offshore GeoIndex alongside a series of other offshore geological maps from the BGS. They are derived from the 1:250 000-scale digital bedrock map of the UKCS, called BGS Geology: marine bedrock 250k, which is available separately from the BGS.

BGS Quaternary deposits thickness

The Quaternary deposits thickness dataset is a digital geological map across the bulk of the UKCS, for areas up to a water depth of 200 m, which shows the thickness of the deposits over bedrock in three categories:

  • less than 5 m Quaternary cover
  • 5–50 m Quaternary cover
  • greater than 50 m Quaternary cover

These depth bands were picked because they represent the horizons that affect offshore infrastructure deployment.

BGS Quaternary deposits summary lithologies

The Quaternary deposits summary lithologies dataset is an offshore digital geological map across the bulk of the UKCS, for areas up to a water depth of 200 m, which groups the deposits into classes based on similar engineering-geology characteristics.

BGS bedrock summary lithologies

The bedrock summary lithologies dataset is digital geological map across the bulk of the UKCS, for areas up to a water depth of 200 m, which groups the bedrock lithologies (rock types) into classes based on similar engineering-geology characteristics.

21CXRM Palaeozoic

21st Century Exploration RoadMap (21CXRM) Palaeozoic petroleum systems analysis project products are a subset of GIS and gridded products included in a larger dataset of reports, images etc. from MEDIN. Devonian and Carboniferous rocks are the focus in and around the Mid-North Sea High, the Central North Sea, the Moray Firth and the Orcadian Basin. Carboniferous rocks are described in the greater Irish Sea area. The work was undertaken by the BGS for DECC/OGA, Oil and Gas UK and oil company sponsors between November 2014 and May 2016, to improve regional digital datasets and knowledge of the under-explored Palaeozoic petroleum systems, and to stimulate exploration. The GIS data includes well picks, two-way travel time and depth grids, gravity and magnetic images.

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 grids of one 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

This 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 via 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's SEA process.

MEDIN

MEDIN is a partnership of UK organisations committed to improving access to marine data. It is an open partnership and its partners represent government departments, research institutions and private companies. MEDIN sits alongside its sibling working group the Underwater Sound Forum (USF). Both groups report directly to the Marine Science Coordination Committee (MSCC).

MEDIN promotes sharing of, and improved access to, marine data and aims to provide:

  • secure long-term management of marine datasets, by setting up a network of data archive centres (DACs)
  • improved access to authoritative marine data held in this network, through a central discovery metadata portal
  • an agreed set of common standards for metadata, data formats and content, maintained and supported by partners
  • guidelines, contractual clauses and software tools to support standards and best-practice data management

The MEDIN portal is a metadata discovery service providing users with a single point of access to a well-balanced, authoritative marine metadata catalogue.

The BGS operates as the data archive centre (DAC) for seabed and sub-sea bed geology and geophysics, provides input to the above portal and further information via the BGS website and the offshore GeoIndex.

Bathymetric DAC

This is found at the 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.