The ½ñÈÕ³Ô¹Ï Superficial Deposit Thickness Model (SDTM) dataset presents the modelled regional variation in thickness of superficial and unconsolidated deposits across Great Britain. These include sediments of fluvial, glacial, marine or anthropogenic origin that were generally formed during the Quaternary (the past 2.6 million years up to today). The thickness of these deposits signifies the depth down to the top of the bedrock, known as geological rockhead.

The distribution of these deposits is not uniform: sometimes they are thin veneers, sometimes they form large, irregular masses, and sometimes they infill entire valleys. The latest SDTM release, the first for over 15 years, includes a raster model of the elevation of rockhead for the first time, providing important data for a variety of different sectors.

The transition between superficial sediments and geological rockhead (and associated bedrock units) is an important zone for geologists, civil engineers, hydrogeologists and environmental scientists because it is where most physical and chemical properties of the deposits significantly change. Properties such as strength, lithology, conductivity, porosity and permeability can be strongly affected by this transition, so an understanding of the depth of the transition zone beneath the ground surface is vital.

The SDTM models have been created using digital mathematical interpolation techniques, combining observations of superficial thickness from borehole logs held in our archives with mapped superficial and artificial geology extents from the 1:50 000-scale digital geological map of Britain.

Version 8 of the SDTM includes the new layer, the rockhead elevation model (RHEM). This is a raster model of the elevation of rockhead relative to Ordnance Datum, the standard vertical reference system used in Great Britain to measure land elevation. This model provides users with an integer value of modelled depth to bedrock in metres and will be of particular use for creating 3D ground models and understanding the geological structure across a site.

The updated SDTM product also contains the observation driven model (ODM), the terrain adjusted model (TAM) and data distance (DataDist).

Observation driven model

The ODM is a raster model of sediment thickness that interpolates thickness values between boreholes within the mapped superficial extents, giving users an integer value of modelled superficial thickness in metres.

Terrain adjusted model

The TAM is a raster model of sediment thickness derived using a method that combines borehole records, the mapped superficial deposit extents and surface elevation data. This differs from the ODM by considering the ground surface elevation, derived from the model, and gives users an integer value of modelled superficial thickness in metres.

Data distance

DataDist is a raster surface defining the distance of any location relative to the nearest source of thickness information; either the location of a borehole or the mapped boundary of a superficial deposit. This is provided as a pseudo-uncertainty surface relative to the ODM, TAM and RHEM components of the SDTM. The further a location is from a source of thickness data, the more uncertain any values provided by ODM, TAM and RHEM models are likely to be.

New naming conventions

SDTM Version 8 has introduced new naming conventions for the ODM and TAM datasets. These name changes better describe the characteristics of the two datasets and removes confusion or implications relating to the terms ‘basic’ and ‘advanced’ that might imply one model is superior. Both model outputs provide valid options and should be considered in tandem rather than in isolation to understand the models’ constraints.

This dataset release marks an important development for the ½ñÈÕ³Ô¹Ï SDTM and is its first update since 2010. Improved borehole selection criteria have been implemented, allowing the models to benefit from the latest interpretations of ½ñÈÕ³Ô¹Ï-held borehole logs as well as identifying and excluding low-confidence, inappropriate and conflicting boreholes that may have been included in previous versions. As such, the borehole selection underpinning SDTM V8 is considered to be more robust, resulting in a higher confidence model.

Rob Shaw, geospatial analyst and SDTM product developer, ½ñÈÕ³Ô¹Ï.

The intended scale of use of this dataset is 1:100 000, with an average vertical accuracy of +/-5 m elevation. The dataset is intended for use at national, regional and city scales, but not site scales where specific ground-investigation works should be undertaken to determine precise superficial thickness and rockhead elevation.

We are continuing our scientific research on to how to improve the prediction of superficial thickness and will build that into any future update of the SDTM.

For more information on the SDTM datasets, including how to access the data, please visit the STDM product webpage, download the or get in touch with ½ñÈÕ³Ô¹Ï Digital Data (digitaldata@bgs.ac.uk).

It is a common assumption that flooding arises as a result of intense rainfall. Whilst this is true in many cases, another common cause is actually groundwater flooding, where groundwater emerges at the surface. Groundwater flooding can occur in a variety of geological settings and poses a significant risk around the UK. In England and Wales alone, it’s estimated that groundwater flooding accounts for around £530 million in damages per year (ESI, 2016). The impacts can be devastating for farmers, local businesses and homeowners, and cause significant disruption across regional transport routes.

½ñÈÕ³Ô¹Ï geologists have started a four-year project that will enhance knowledge of ground conditions and undertake flood-pattern investigations around the River Tweed. This survey will provide crucial geological data for local authorities, organisations and others involved in land-management initiatives to the benefit of the 450 000 people who live in or around the flood-prone Borders region.

Much of the region was last surveyed in the 1920s (or earlier) and this latest project forms a central part of ½ñÈճԹϒs current national geological mapping programme. The picturesque landscapes so synonymous with the famous salmon river have been formed over millions of years. Most recently, they were sculpted by ice during the last glaciation, which ended around 19 000 years ago in the Tweed catchment.

Existing maps indicate that the area is dominated either by glacial till or bedrock but, in reality, it is a lot more complex than this, with a continuum from bedrock through weathered bedrock, slope deposits and till. These nuances will be a particular focus for geologists as they are likely to have an effect on how groundwater moves through the shallow subsurface, due to the more open pore space of slope deposits compared to till or bedrock. This enhanced understanding will help to provide baseline data for flood monitoring and forecasting for those in the environmental modelling and policy communities, as well as landowners, to make more informed decisions about the management of land in the catchment area.

Our understanding of glacial systems has evolved enormously in the hundred years since the Tweed catchment was last surveyed. In the 1920s, geological surveys were performed solely by walkover surveys, but now we are able to take advantage of high-resolution Earth observation data to understand and model these systems.

Creating new maps using a modern understanding of how ice sheets develop combined with this new data will improve our understanding of this crucial waterway and may enable us to use additional knowledge of ground conditions to assist with land-planning initiatives that will help manage flooding.

Sam Roberson, ½ñÈÕ³Ô¹Ï Quaternary geologist and Tweed project lead.

The Tweed project is exploring new technologies to create geological maps, combining artificial intelligence, high-resolution terrain data and field observations to understand how the different deposits affect the shape of our landscapes. Field studies began in the Cheviot Hills in spring 2025, before heading to the Tweedsmuir Hills during summer 2025 and around Melrose and Galashiels during autumn 2025. All fieldwork is completed on foot, making observations about the sedimentary exposures and the form of the landscape.

Geological maps produced from this work will form part of the national geological map, which can be freely accessed on the ½ñÈÕ³Ô¹Ï maps portal or via the on the ½ñÈÕ³Ô¹Ï website. Research papers and reports will also be accessible via the ½ñÈÕ³Ô¹Ï website and the service.

Over 95 per cent of the water supply for the Tweed catchment, home to Berwick-upon-Tweed, is provided by groundwater. The Fell Sandstone Formation is the principal aquifer supplying drinking water, as well as being a vital resource for farming and industry in the region. Careful management of this critical resource is particularly important in a changing climate.

Climate projections indicate that, by 2050, the north-east of England may see summer and winter rainfall at 31 per cent lower and 25 per cent higher than current averages, respectively. Drier summers and wetter winters will affect the water balance in the aquifer, so understanding and accounting for the anticipated changes are critical in ensuring sustainable abstraction.

Nearly a century on from the last geological survey of the Berwick-upon-Tweed area, the Environment Agent (EA) commissioned ½ñÈÕ³Ô¹Ï to review the geological map of the area to inform a new groundwater flow model of the Fell Sandstone Formation. This work was needed to improve understanding of the regional groundwater system, strengthen the evidence base for water security and support key decisions in the abstraction licensing strategy.

Ultimately, the mapping of the aquifer will help the EA, water abstractors and the local community to ensure sustainable abstraction and reduce risks from contamination to protect the water quality. This informed management will help to ensure the water supplies for Berwick-upon-Tweed are resilient to climate change.

We have commissioned the British Geological Survey to undertake this new survey of the Fell Sandstone Formation and surrounding strata to help us undertake our regulatory role in protecting groundwater underlying Berwick and the surrounding area.

The updated mapping will improve our understanding of the regional groundwater system and any implications on the future availability of water and climate change impacts. This will help in considering applications for new abstraction licences or renewals and/or increases of existing abstraction licences, where we require good quality and up-to-date information on the water environment.

Diane Steele, senior north-east area groundwater technical specialist, EA.

The new geological mapping and groundwater modelling have revealed that the local aquifer system is more complex than previously thought, with compartmentalisation of the groundwater system within the Fell Sandstone Formation aquifer as well as connectivity between the aquifer and water-bearing sandstone bodies in the adjacent rock formations. This work is informing a programme of borehole drilling by the EA to further develop our understanding of the interactions between water-bearing sandstones in Fell Sandstone Formation and underlying strata, and the implications for future water supply.

The new geological maps are being used as inputs for groundwater modelling, which is a key tool to better understand the controls on groundwater flow within the aquifer. Developing our understanding of the connectivity within the aquifer system is critical for assessing the effects of abstractions and evaluating the potential impacts of both changes in usage and changes in climate, helping to ensure the groundwater resource can support the region well into the future.

Tim Kearsey, head of ½ñÈÕ³Ô¹Ï Integrated Geology.

The geological map data produced from this work will form part of the national geological map and will be freely accessible via the  in its next update. More information on the mapping of Berwick-upon-Tweed can be found on .

The British Geological Survey (½ñÈÕ³Ô¹Ï) has released a new shallow subsurface geological synthesis of the southern North Sea in the first formal review of this region since the 1990s. A wealth of new subsurface data has been generated through the rapid expansion of offshore wind farm (OWF) development since the last assessment.

In total, the new synthesis draws on data from 22 OWFs and cable landfall sites from recent publications and open data available through The Crown Estate’s . Bringing these diverse datasets together presented a rare opportunity to enhance our geological understanding of the region, providing a detailed baseline resource to support more efficient and better-informed offshore development projects in the future.

Findings from the updated review have revealed much greater geological complexity within the region than indicated by the previous assessment, which was developed between the 1970s and 1990s on the back of data collected during oil and gas developments. Modern OWF investigations, supported by comprehensive borehole drilling, cone penetration tests and seismic datasets, show that many of the geological formations contain a variety of distinct sedimentary characteristics. This complexity has direct implications for foundation design and ground modelling, including the identification of geo-engineering constraints and geohazards, which is crucial information for a wide range of offshore infrastructure development.

The assessment examined evidence across pre-glacial, glacial, interglacial and post‑glacial periods from 200 million years ago to the present day. Understanding how different sedimentary units were deposited provides vital insight into geological formations that may present specific geo-engineering complications. This includes mixed soils, boulders, glacially compacted sediments or organic-rich layers. Organic units can be problematic for cable installation due to their fibrous nature, presenting considerable challenges to cable routing.

It is not a requirement for UK offshore infrastructure projects to collect samples for dating and biostratigraphy; however, where they are available, absolute dating (radiocarbon and optical stimulated luminescence data) information has also been included within the assessment. Neighbouring countries such as the Netherlands recognise the value of this data, as it can help to better predict age-based sedimentary characteristics and ultimately better inform geotechnical characterisation around a project’s design.

The report outlines several recommendations to enhance the resource further, including improving fine-scale mapping, ingesting geotechnical datasets for each geological subunit and strengthening international collaboration to harmonise North Sea stratigraphy. The findings presented in the main report can be aligned with results presented in the , which is a data catalogue highlighting the key geological features and associated engineering constraints for OWF development as part of the . Both resources provide complementary datasets and criteria essential for evaluating OWF site suitability.

This work provides:

• an opportunity to advance scientific understanding
• resources to strengthen national collaboration
• supporting baseline evidence for the energy transition, energy security and wider marine planning
  

The release of this report marks an important milestone in compiling geological observations from literature and offshore wind farm development over the past 30 years or so. It brings together a wealth of new offshore geological data that enhances our understanding of the shallow subsurface in the marine environment in the southern North Sea. We hope this dataset will provide strong baseline evidence to support national and international collaboration for efficient offshore development and act as a blueprint for other areas around the UK Continental Shelf.

Nikki Dakin, ½ñÈÕ³Ô¹Ï Senior Marine Geoscientist

We would encourage similar consolidation of geological information across the wider North Sea, Celtic Sea, Irish Sea, The Solent and English Channel, making full use of the substantial dataset holdings within the Marine Data Exchange. There is also significant potential to extend this approach internationally, working with neighbouring countries.

Such data provides a robust evidence base for industry, regulators and researchers, marking an important step toward a fully modernised geological model and improving our understanding of offshore stratigraphy across the UK Continental Shelf.

The report and geological assessment are now available online: .

½ñÈÕ³Ô¹Ï would like to acknowledge The Crown Estate as well as wind farm developers for contributing reports and data to The Crown Estate’s Marine Data Exchange.

The ½ñÈÕ³Ô¹Ï BritPits dataset contains more than 264 000 records of onshore mineral workings located in Great Britain, Northern Ireland, the Isle of Man and the Channel Islands. The data includes active, inactive, dormant and ceased sites, as well as a range of mineral operations including mines, quarries and onshore oil and gas fields, together with wharfs and rail depots handling mineral products and industrial processes. Each record describes an onshore mineral working in terms of its name, operational status, geographical location, Mineral Planning Authority (MPA), operator, geology, worked mineral commodity and a range of relevant metadata.

Three levels of ½ñÈÕ³Ô¹Ï BritPits data are available. The open-source index is based on the full BritPits dataset but contains index level information only, including the name, status and location of the working. This can be accessed as a Web Map Service (WMS) layer or via the . The other two levels are available as licensed datasets.

• The open-source index package is available under an Open Government Licence
• The full dataset includes all the entries of the ½ñÈÕ³Ô¹Ï BritPits database, including historic sites; this data is also available for specific Mineral Planning Areas
• A subset of the full dataset that contains only the active, inactive and dormant mines and quarries (over 5200 entries)

These datasets are updated every year. The latest version, released in February 2026, contains 264 549 records, an increase from 262 814 records in the previous version.

This data will be of use to organisations in the public and private sector who have an interest in the location of mineral extraction sites and their possible after-use. For example, the data has been supplied to:

• national and local governments for use in planning and statistical studies
• non-governmental organisations for environmental and conservation planning
• commercial organisations for analysis of resource potential and legacy operations

As the UK works toward its net zero ambitions, attention is increasingly turning offshore, where geological formations under the sea floor may hold the key to long-term carbon dioxide (COâ‚‚) storage. 

Carbon capture and storage (CCS) encompasses a range of technologies designed to significantly reduce emissions from large industrial sources such as steelworks, cement plants and thermal power stations. COâ‚‚ is captured at source, transported and then injected into suitable rock formations deep beneath the surface, typically at depths of over 800 m. Geologists at ½ñÈÕ³Ô¹Ï are working to better understand the subsurface geology of the Central North Sea and its suitability for storing COâ‚‚ captured from major industrial sources. This work could release one of the UK’s largest, yet least-developed, carbon storage resources and underpin the in CCS projects.

Despite accounting for approximately 60 per cent of the UK’s total estimated COâ‚‚ storage capacity, the Central North Sea remains under-represented and highlights a major opportunity for the Government’s clean energy growth agenda. 

A nation rich in storage potential 

Deploying CCS at scale is a key pillar of the UK Government’s . Current ambitions are to store at least 50 million tonnes of COâ‚‚ per year by 2030, rising to as much as 170 million tonnes annually by 2050. 

The UK is exceptionally well positioned for offshore COâ‚‚ storage. Estimates suggest that total theoretical storage capacity exceeds 70 billion tonnes. The North Sea Transition Authority (NSTA), which regulates offshore COâ‚‚ storage, launched its first competitive licensing round in 2022 and followed this with a second round announced in December 2025. 

These licences allow operators to explore and appraise potential storage sites as a precursor to applying for permits that enable COâ‚‚ injection. Due to favourable geology and proximity to onshore emission hubs, most licences to date have been located in the Southern North Sea, with additional clusters in Liverpool Bay, Morecambe Bay and the Northern North Sea. However, the region with most storage potential lies elsewhere.

The drive to map this untapped potential

The enormous, currently untapped potential beneath the Central North Sea lies in extensive sandstone formations in the region. Multiple sequences of stacked Palaeogene sandstone units represent a vast potential COâ‚‚ storage resource, with more than 10 billion tonnes of theoretical capacity (approximately one quarter of the basin’s total regional storage capacity). These sandstones were deposited between 40 and 65 million years ago in deep-water marine fan systems. The complex stacked and interdigitated nature of these sandstone bodies raises important geological questions that must be resolved before large-scale storage can proceed.

Key considerations include: 

• the degree of connectivity between sandstone units, which has a bearing on pressure during CO₂ injection
• balance between pressure dissipation and pressure interference between neighbouring storage sites, which affects storage capacity
• the effectiveness of the vital sealing layers above and between the sandstone formations, which might be prone to disruption by various geological phenomena
• legacy oil and gas wells, which could act as pathways for CO₂ to escape if not properly assessed

With relatively few licences currently issued in the Central North Sea, robust pre-competitive geological understanding is essential to realise the region’s storage potential. ½ñÈÕ³Ô¹Ï geologists have therefore begun a comprehensive programme to better understand the Palaeogene storage system. This work will also help to address regulatory and operational challenges, particularly those related to pressure effects and interactions between disparate storage projects.

John Williams, senior geoscientist at ½ñÈÕ³Ô¹Ï.

Decades of oil and gas exploration have generated a wealth of subsurface data, including drill core that is curated in ½ñÈճԹϒs National Geological Repository. Drilling core is expensive, costing as much as £20 to 30 million for a single offshore borehole, so the ability to access pre-drilled material is invaluable, both in terms of avoided drilling costs and time saved. Alongside this archived material, ½ñÈճԹϠhas also developed an integrated subsurface database and interpretations comprising existing 3D seismic and well data, and a stratigraphical framework to ensure accurate regional interpretation.

From the late 1990s to the early 2000s, ½ñÈÕ³Ô¹Ï undertook pioneering work to evaluate the potential to reduce greenhouse gas emissions by storing COâ‚‚ in rocks offshore UK, to help mitigate climate change and develop clean energy. This early work focused on the geological storage opportunities in the Southern North Sea and East Irish Sea regions.

Potential storage sites in these regions, first identified by ½ñÈÕ³Ô¹Ï, are among the first to be licensed and permitted by the NSTA for COâ‚‚ storage. For the UK to reach its ambition of storing 170 million tonnes of COâ‚‚ a year by 2050, it will need to look beyond the current well-appraised geographical areas.

The stacked sandstones of the Central North Sea are relatively under-studied, with huge CO₂ storage potential. Our ambition is to assess and characterise the potential geological storage system in this region to enable future CO₂ storage in the UK, fast-tracking the nation’s CCS industry.

Michelle Bentham, chief scientist for decarbonisation and resource management at ½ñÈÕ³Ô¹Ï.

½ñÈÕ³Ô¹Ï is seeking to establish partnerships to help unlock this nationally significant COâ‚‚ storage resource, which could play a crucial role in the UK’s transition to a low-carbon future. Interested parties should contact John Williams via enquiries@bgs.ac.uk

½ñÈÕ³Ô¹Ï has developed a new, national-scale, offshore dataset that shows the distribution of previously interpreted Quaternary rock layers in the shallow subsurface of the UK continental shelf.

The ½ñÈÕ³Ô¹Ï Offshore Quaternary 250K dataset comprises a compilation of legacy ½ñÈÕ³Ô¹Ï 1:250 000 Quaternary geology map sheets, which were first published in the late 1980s to early 1990s. Large areas of the UK offshore are covered at a scale of 1:250 000 and this is the first time these map sheets have been digitised and merged together.

The dataset is made up of vector polygons, each representing an area where a particular formation has been mapped. The legacy map sheet interpretations have not been modified during the digitisation; they are presented in their original form and have been ‘mosaiced’ together as a single digital product.

The dataset will help users, particularly those in the offshore renewables sector, to understand the stratigraphy that was mapped historically in a particular area and can be used for reference when completing site investigations.

The principal drive behind this release is to make original 1:250 000 map data available in a digital format. Although work to refine Quaternary stratigraphical frameworks is ongoing, the map compilation is not informed by new data or analyses.

The Offshore Quaternary 250K dataset is the first time that these legacy offshore map sheets will be digitised, making it easier for users to access the data than ever before.

Andrew Dyson, marine geoscientist at ½ñÈÕ³Ô¹Ï.

Geologists at ½ñÈÕ³Ô¹Ï have completed a major update to the geological map of the Yorkshire Wolds, where the underlying rocks and sediments play a vital role as natural reservoirs for the region’s underground water resources.

The distinctive white chalk rock of the , which forms the magnificent coastal cliffs, is also present beneath the wolds. The chalk is an ‘aquifer’ and is important as the primary drinking-water source for the area. The new geological mapping will provide detailed and accurate information to inform decision making around the use of groundwater resources.

The geology of some of the area was last mapped in the 1800s, before modern understanding of the impact of tectonics (movement of the ’plates’ that make up the Earth’s crust) on the chalk and before information about differences in the properties of the chalk layers was recorded. At that time, there was no satellite data and underground data was limited, so maps were mostly based on ground observations, with much of it done from horseback! The new mapping provides updated geological data and information for the region and plays a central role in the current ½ñÈÕ³Ô¹Ï national geological mapping programme.

The five-year project involved different remote techniques, including interpretation of 2D seismics (information from small, controlled vibrations that create waves through the rock, which can then be used to map the subsurface), digital elevation models, aerial imagery and borehole records along with field surveys and palaeontological (fossil) analysis. Collectively, these methods and data have significantly improved geological understanding of the chalk aquifer.

The aquifer currently faces a number of pressures, including:

• increased water demand from a growing population as well as industrial uses
• risk of nitrate contamination from agricultural land practices
• risk of salt water from the Humber estuary reaching the aquifer and mixing with drinking water
• improvements to habitats, for example chalk streams

We need to better understand and model how water flows in the Chalk aquifer and the interaction between springs, rivers and abstraction. The new mapping delivers enhanced knowledge that will help to improve regional understanding of both the aquifer and the groundwater resources, as well as localised geological issues that may assist in reducing risks to specific water supply assets, such as water abstraction sites.

Over the past hundred years since the geology of the Yorkshire Wolds was last mapped, our ability to better understand what lies beneath our feet has vastly improved thanks to technological advances and a modern understanding of geology. The updated geological maps will help companies, farmers, local planners and regulators make more informed decisions around the management and protection of the chalk aquifer in the Yorkshire Wolds.

The data also provides a solid geological framework to underpin future work to help mitigate present and future issues faced in the Yorkshire Wolds, including drought, coastal erosion, water quality and saline intrusion into the aquifer.

Laura Burrel Garcia, survey geologist at ½ñÈÕ³Ô¹Ï.

The project was a collaboration between the Environment Agency (EA), Yorkshire Water Services Limited (YWS) and ½ñÈÕ³Ô¹Ï. Recently, EA, YWS and WSP attended ½ñÈճԹϒs headquarters in Keyworth, Nottinghamshire, to discuss the conclusion of the project and its outcomes.

The team at the ½ñÈÕ³Ô¹Ï has not just remapped the Yorkshire Wolds; they have also shared their expertise and enthusiasm with all. The outputs of this project will benefit the people of Yorkshire for centuries to come and will greatly assist the Environment Agency in our work to create better places for people and wildlife, while supporting sustainable development.

Ruth Buckley, Environment Agency.

This project has been a wonderful example of collaboration and shared learning. The ½ñÈÕ³Ô¹Ï team members were generous with their time, sharing their expert knowledge of field mapping and interpreting the modern information. It was a pleasure to work with them. The end result is a huge improvement in the collective understanding of the geology, which will feed into improvements in understanding of groundwater flow and a new groundwater model based on the new geology maps. This gives us the ability to better manage East Yorkshire’s water resources and protect the environment now and into the future.  A big thank you to all involved.

Mark Morton, Yorkshire Water Services Limited.

The data produced from this work will form part of the national geological map, which will be freely accessible via the .