The SEA portal is managed by the BGS on behalf of DECC and provides free access to downloadable data, information and reports which have been produced through the SEA process. The Department of Trade and Industry (now DECC) began a sequence of sectoral SEAs of the implications of further licensing of the UK Continental Shelf (UKCS) for oil and gas exploration and production in 1999. The SEA Process subdivided the UKCS into eight areas shown; beginning in 2008, integrated Offshore Energy SEAs have been undertaken that cover the whole UKCS. An integral part of the SEA programme has been a series of research and monitoring surveys commissioned to acquire new data about the offshore environment and used to help inform the relevant SEAs. Many files can be downloaded directly from portal. Those that are too large to download can be ordered via the website for postal delivery from BGS.

This is the collection of cores and samples held by BGS for the sea areas around the UK. It includes material collected by BGS during its mapping projects and material donated to BGS by other organisations. The main core and sample types are grab samples (sea-bed), gravity cores, vibrocores and rock-drill cores (up to 6m in length), and borehole cores (up to 274m in length). The sea-bed grab samples are Holocene sediments present at the sea-bed and are stored in plastic jars. Where possible, sub-sample material has been retained after analysis. The bulk of the cores consist of Holocene and Pleistocene material. The rest are of bedrock ranging in age from Neogene to Pre-Cambrian. A lot of the core was collected in plastic liner tubing and the unlithified cores have been split vertically. The bulk of the material was collected in the late 1960s, 1970s and 1980s and early 1990's with ongoing additions of new sample and cores each year. The distribution is very variable, but, in general, there are grab samples and/or shallow cores spaced about every 5 - 10km across the entire UK Continental Shelf. In some localised areas the sampling density is much higher. The samples and cores are applicable to a wide range of uses including environmental, geotechnical and geological studies.

This data set contains the following original data for the deep seismic reflection surveys conducted by the BGS in various parts of the UK. The data consists of observers' logs, surveyors' reports, location data tapes, field data recording tapes and processed data tapes. The processed tapes are at various stages of processing from demultiplexed field data to migrated stack (not all available for all profiles) These data are kept as archive copies. They are generally available for academic and commercial use, subject to payment of fees (and, in a few cases, the agreement of co-owners of the data rights). There are Approximately 20 files of written records and 200 tapes.

This is a digital version of the paper based 1:1M scale Offshore Quaternary map, North and South sheets. Customers should be aware that, given the age of the paper based maps, the digital version is not quality assured and BGS can accept no liability for the information held on the digital map. In addition, published 1:250,000 Quaternary maps are available. These contain more detailed subdivision of the Quaternary succession. The original paper based map covers the UK Continental shelf. The paper map is symbolised using lithology and chronology. The lithological boundaries were compiled from the data published in the BGS 1:250,000 Quaternary Geology map series and from revised interpretation of core and borehole data. Core and borehole sites are commonly 5 to 20 km apart, thus the lithological divisions are generalised. The formations and sequences identified by BGS have been grouped into Quaternary age ranges. The geological codes assigned to the digital version of the map have been compiled using the key information held on the paper map. The LEX-ROCK style codes combine the lithology and chronology and have been subject to the standard BGS approval process.

BGS offshore marine products are made available to view via this web map service. The 1:250 000 scale offshore geological maps in the UTM series (Universal Transverse Mercator projection) are available digitally as two themes: bedrock geology (DigRock250) and sea-bed sediments (DigSBS250). Marine Hard Substrate Dataset (DiGHardSubstrate250k) is also made available via this service.

Particle Size Analysis (PSA) and organic carbon content data from marine sediment sampling of two plots within the Trevose Box off south-west England between 14 - 18 April 2023 before and after fishing. This DEFRA funded FISP (Fisheries Industry Science Partnerships scheme) project aimed to understand the acute effects of scallop dredging and beam trawling on seabed carbon. The project was led by Bangor University in collaboration with Imperial College London, CEFAS, Western Fish Producers Organisation and the South Western Fish Producer Organisation. The study was conducted in two areas offshore south-west England, UK. The areas were within the Trevose box, which is a management area closed to bottom fishing for the months of January, February and March each year. This allowed us to sample areas which had not been exposed to fishing immediately before our sampling which would reduce the chance of seeing any effect from our experimental fishing. One plot was designated an area that would be experimentally fished by a beam trawler, and another by a scallop dredger (Figure 1). The plots were chosen to minimise differences in depth, seabed habitat, sediment type, wave energy and tidal currents within and between them. Both were chosen where their respective types of fishing gear had been used previously, although scallop dredging has been less common in this area in recent years. The sampling from the RV Prince Madog and experimental fishing from the fishing vessels took place between 14 – 18th April 2023. Before any fishing activity took place, grab sampling was conducted in the dredge plot and in the beam trawl plot that would be later fished to varying amounts, which will be referred to as ‘Times fished’ or ‘fishing intensity’. A 0.1 m2 Day grab was used. When the day grab was onboard two cores were used to subsample the grab sample as deep as possible, these were then sliced in 1 cm intervals and frozen onboard for later carbon analysis. A homogenised sample from the day grab was also taken for Particle Size Analysis. After the ‘Before’ grab samples were taken, a beam trawler and scallop dredger towed their gear along the sampled lanes in each respective plot. The 'After’ samples were taken after that fishing activity. Please see report for full details on how the PSA and organic content values were determined. Whitton, T.A., Austin, M., Newbould, A., Kennedy, H., Allender, S., Cavan, E., Parker, R., North, C., Hatchman, J., Hiddink, J.G. (2024) The impact of mobile demersal fishing on blue carbon in seabed sediments. Report to DEFRA. https://research.bangor.ac.uk/portal/en/researchoutputs/the-impact-of-mobile-demersal-fishing-on-blue-carbon-in-seabed-sediments(1fa1845a-6669-4b5b-83e1-234a6eafc75c).html

Data from the British Geological Survey's GeoIndex Offshore theme are made available for viewing here. GeoIndex is a website that allows users to search for information about BGS data collections covering the UK and other areas world wide. Access is free, the interface is easy to use, and it has been developed to enable users to check coverage of different types of data and find out some background information about the data. More detailed information can be obtained by further enquiry via the web site: www.bgs.ac.uk/geoindex.

The BGS Offshore Bedrock 250k dataset is vector data which reflects the offshore bedrock geological of the UK and some of its adjacent waters at 1:250,000 scale. This comprehensive product provides a digital compilation of the paper maps published by BGS at the same scale, as well as, additional re-interpretations from regional geological studies. The composition, age and deformational history of the rocks underlying the seabed (bedrock) are important for a range of stakeholders, including marine spatial planners and offshore developers. The dataset is arranged in two GIS layers: Bedrock Lithostratigraphy and Bedrock Structural Geology. The polygons within the Bedrock Lithostratigraphy layer show the spatial distribution of the principal lithostratigraphical units (formations and groups). The lines within the Structural Geology layer show the location and extent of known structural features such as faults and folds. This broadscale dataset was derived from geophysical data (e.g. airgun, boomer, sparker, sidescan sonar, magnetometer, gravity meter) and data obtained from commercial wells and BGS shallow boreholes. The variations in data density will be reflected in the detail of the mapping.

Data from the British Geological Survey's GeoIndex Offshore (cultural data) theme are made available for viewing here. GeoIndex is a website that allows users to search for information about BGS data collections covering the UK and other areas world wide. Access is free, the interface is easy to use, and it has been developed to enable users to check coverage of different types of data and find out some background information about the data. More detailed information can be obtained by further enquiry via the web site: www.bgs.ac.uk/geoindex.

This dataset comprises data from Wessex Archaeology surveys which were conducted over various wreck sites between 2003 and 2010. Three of these datasets were acquired in English waters, one in Welsh waters and one in Scottish waters. The geology and geophysics component of the data are archived by British Geological Survey (BGS) in the Marine Environmental data and Information Network (MEDIN) Data Archive Centre (DAC) for Geology and Geophysics. The data include multibeam echosounder, single-beam echosounder, sidescan sonar, sub-bottom profiler, magnetometer, and geological data (vibrocore logs and photos). Data were also provided to other archive centres as appropriate - UKHO (bathymetry), Royal Commission Ancient and Historic Monuments Wales (geophysics), Royal Commission on the Ancient and Historical Monuments of Scotland (geophysics and diving/ROV), Archaeology Data Service (diving/ROV). Although generated for archaeological purposes, these high quality and resolution data are capable of re-use by marine surveyors and scientists from a range of different fields. Data are delivered via the BGS Offshore GeoIndex www.bgs.ac.uk/GeoIndex/offshore.htm and additional data are available on request enquiries@bgs.ac.uk.