GeoIndex help | Offshore map theme

View the offshore GeoIndex

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

Seabed samples

A number of datasets are available either in digital or analogue versions.

Digital data archive

  1. Particle size analyses
    This dataset results from particle size analysis of BGS offshore samples. The bulk of the data are derived from analysis of seabed sediments. Analysed fractions are retained for further examination and analysis. The dataset includes gravel, sand and mud fractions, carbonate content and phi/half phi analysis of the sand fraction.
  2. Geotechnical
    This dataset results from geotechnical analysis of BGS offshore core material. The main data consists of compressive and shear strength measurements made using hand vanes. Expert advice is required in the use of the data.
  3. Marine geological descriptions
    Coded marine geological descriptions of the various types of seabed sediment unit found in offshore samples.
  4. Geochemical analyses
    The sea area around the United Kingdom is used for a wide range of human activities, all of which have a significant impact on the marine environment. The naturally occurring concentrations of chemical elements in seabed sediments may be enhanced by contaminants introduced by input from rivers and the atmosphere and by more localised sources arising from shipping operations, exploitation of oil and gas, and by direct discharges from drainage systems, sewage outfalls, effluents from industry and waste disposal at sea. It is therefore important to identify the 'background' components of sea-floor sediments that are inherited from the rocks or older sediments from which they are derived and those that have been introduced into the environment.

    BGS offshore geochemical data, consisting of a set of 38 elements, are available from seabed samples collected from a variety of sediment types occurring in a wide range of environments. Samples have been collected offshore off the eastern shores of the UK, where heavily populated and industrialised catchment areas are drained by major rivers such as the Thames, Humber and Tyne, flowing into the North Sea. In contrast, samples are also available from the continental shelf west of Scotland, where man's activities have had considerably less impact. The data provide a baseline for chemical element concentrations in seabed sediments, against which samples collected in the future may be assessed. It should therefore be of significance to a diverse range of interests including pollution control, fishing, natural resources, nature conservation, shipping, tourism, recreation, and waste disposal management. In addition, the information derived from the data will be of use to geologists in identifying the source of seabed sediments and any underlying deposits.

Analogue data archive

  1. Sample description sheets
  2. Borehole logs
    BGS has drilled offshore boreholes since 1969. The logs of these boreholes have been compiled in the field and also back in the office. This dataset comprises the composite borehole logs plus paperwork, which includes descriptions of rocks and/or unconsolidated sediments.

Core archive

  1. Borehole core material
    This material is collected by BGS from the sea areas around the UK during wireline drilling operations.
  2. Vibrocore samples
    The core material was collected by BGS from the sea areas around the UK during vibratory coring operations to a maximum penetration of 6 m.
  3. Gravity core samples
  4. Surface samples
  5. Analysed fractions of seabed samples
  6. Offshore boreholes

Regional airborne magnetic survey areas and flight lines

The surveys include:

  • Analogue airborne magnetic surveys of Great Britain for the Geological Survey (GSGB), which was subsequently digitised.
  • Commercial analogue survey of North Sea by Aeroservices Inc, subsequently digitised by BGS.
  • Commercial digital (+ one analogue) surveys off NW/N/NE of Britain by Huntings Geology and Geophysics, purchased outright by BGS.
  • Local surveys, digital and analogue aeromagnetic (+ other methods) surveys for BGS and commercial companies.

Marine gravity and magnetic readings

Unadjusted ship gravity, magnetic and bathymetry data acquired by BGS as part of its Offshore Reconnaisance Mapping Programme. This programme commenced in 1967, and was funded mainly by the Department of Energy. Unadjusted ship gravity and bathymetry data from various commercial and academic surveys between 1965 and 1994. Confidential MOD Hydrographic Office integrated ship gravity and magnetics surveys of North West Europe marine areas for which BGS acts as agent. Network adjusted gravity and magnetic compilations of data from BGS and non-BGS sources.

Marine geophysical survey lines

The path the survey ship took whilst undertaking the ship gravity, magnetic and bathymetry survey.

For more information on the geophysical datasets available from BGS, please see digital products.

Marine Environment Data and Information Network (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).

More information is available at the MEDIN website.

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

  • secure long-term management of marine data sets 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 format 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. Search the MEDIN Data Archive Centres.

BGS operates as the Data Archive Centre (DAC) for seabed and sub-seabed geology and geophysics, provides input to the above portal and further information via the BGS website and the Offshore GeoIndex.

The BGS Marine Survey Data Management Handbook describes the management of BGS marine survey data.

BGS has created a Survey Folder Structure 150 KB pdf for geological and geophysical survey data which can be used offshore and for submitting data to BGS. This folder structure may be adopted by external organisations and can be used for submission of data to the BGS MEDIN DAC.

BGS MEDIN DAC: Oil and gas industry site surveys

As part of the BGS MEDIN DAC, we hold information about oil and gas industry site surveys. The Offshore GeoIndex 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.

Department of Energy and Climate Change (DECC)

BGS are showing selected DECC offshore data so they can be viewed in context against data and information available from BGS. The source data is from the DECC Offshore maps and GIS shapefiles. These are DECC owned data.

The primary location for comprehensive UK Oil and Gas Industry information and data access is the UK DEAL website.


The DECC website also makes available a range of offshore data and information. For more details, see DECC Data & maps.

SEA Data Portal

The Strategic Environmental Assessment (SEA) data portal is managed by BGS on behalf of DECC and contains free access to available information and reports which have been produced through the SEA process. Many files can be downloaded directly and those that are too large to download can be ordered via the website.


DEAL is the gateway to information on the UK Offshore Oil & Gas Industry and provides quick and easy access to catalogues of data available from release agents, geophysical companies and licence operators alike. DEAL is:

  • a register of all wells, surveys, licences and infrastructure
  • a directory of released and proprietary well and seismic data
  • a unique source of metadata for the UKCS

Registration allows users to carry out both map and form based searches on catalogues of released well and seismic data, subscription provides access to advanced facilities.

Median lines

Agreed boundaries between international offshore designated areas.

Quadrants and blocks

A quadrant is a means of dividing offshore areas in to identifiable parts. Blocks are a subdivision of a quadrant.