As sea levels continue to rise today, coastlines around the world are changing before our eyes. Cliffs retreat, beaches migrate and storms re-shape the shoreline. However, these processes are not new.

Scotland after the last glacial maximum

Around 20000 years ago, Scotland and much of Britain were buried beneath the British–Irish ice sheet. As the climate warmed, the ice gradually retreated, leaving behind a landscape sculpted by ice. Among the most distinctive features are drumlins: teardrop-shaped hills with rounded crests, commonly formed of glacial sediment deposited beneath flowing ice and often occurring in large ‘swarms’.

The contraction and eventual disappearance of the ice also triggered changes in relative sea level. Globally, melting ice sheets caused sea levels to rise while locally, the land itself slowly rebounded (the amount varies with geography) after being released from the enormous weight of the ice sheets. These competing processes meant that coastlines continually shifted position through time, with some areas submerged while others emerged from the sea.

Hidden coastlines beneath the sea

Recent advances in high-resolution seabed mapping have revealed extensive fields of submerged drumlins across the Irish Sea and along Scotland’s west coast. Although these landforms were created beneath the last British–Irish ice sheet, many no longer preserve their typical rounded crests. Instead, numerous drumlins display flat-topped or truncated morphologies associated with gravel tails, tombolos, spits and gravel barriers. These assemblages closely resemble modern eroding drumlin coasts observed in western Ireland and eastern North America, where wave action progressively removes sediment from drumlin coasts and redistributes it along the shoreline.

51ΑΤΖζ scientists have therefore interpreted the submerged drumlins as the product of wave erosion during periods when relative sea level remained lower than today. As sea levels subsequently rose, the former shorelines were drowned and preserved beneath the sea. They provide geomorphological evidence of past coastal positions and former relative sea-level lowstands.

Why do these ancient shorelines matter?

Reconstructing past relative sea level is essential for understanding how the British landscape evolved following deglaciation. Existing reconstructions are based largely on glacial isostatic adjustment (GIA) models, which simulate the combined effects of global sea-level change and uplift of the Earth’s crust following ice-sheet retreat. The submerged, truncated drumlins provide an independent geomorphological record against which these models can be tested. At several locations, the depths of the truncated surfaces indicate sea-level lowstands that are lower than those predicted by current GIA models, suggesting that regional reconstructions may require refinement.

These findings demonstrate the value of submarine geomorphology for improving our understanding of post-glacial coastal evolution. As increasingly detailed seabed mapping becomes available, submerged landscapes are providing new evidence to refine sea-level reconstructions and improve our understanding of how coastlines responded to environmental change following the last ice age.

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Researchers from BGS recently visited Iceland as part of a Research and Innovation Scotland (RIS) International Collaboration Fund project aimed at developing international partnerships and identifying opportunities for future collaborative research. The three-day visit brought together researchers working across marine geoscience, volcanology, geological hazards, geothermal energy, carbon storage and offshore infrastructure from organisations including Iceland GeoSurvey (ÍSOR), the Icelandic Meteorological Office (IMO), the University of Iceland, Carbfix and BGS.

The proposal was developed through discussions between BGS scientists based at the Lyell Centre, in collaboration with Prof Eric BrΓ©ard at the University of Edinburgh, with the aim of connecting expertise in marine geoscience, volcanology and hazard assessment with Iceland unique geological setting and internationally recognised expertise in active volcanic and geothermal systems.

A key objective of the RIS-funded activity was strengthening connections between researchers and organisations based in Scotland and abroad working across complementary scientific disciplines. Through a combination of workshops, field visits and technical discussions, the visit provided an opportunity to develop new relationships, exchange knowledge and identify future collaborative research opportunities.

The visit also built upon relationships established through previous collaboration between BGS and ÍSOR, including the ‘Offshore and coastal region geological and geomorphological assessment: Icelandic windfarm suitability’ (OGGA-IWS) project undertaken in 2024.

ÍSOR hosted a workshop that brought together researchers from BGS, ÍSOR, the Icelandic Meteorological Office and the University of Iceland. Presentations covered marine geophysical surveying, geological hazards, volcanology, offshore infrastructure, geothermal energy, carbon storage and approaches to translating scientific understanding into practical decision making.

ÍSOR colleagues presented newly acquired marine geophysical datasets and outlined plans for using their recently acquired multichannel sparker system for a wide range of marine investigations. Discussions highlighted opportunities to combine Icelandic marine geophysical acquisition capabilities with BGS expertise in marine geological interpretation, hazard assessment and offshore infrastructure characterisation.

Field visits to the Reykjanes Peninsula provided an opportunity to observe recent volcanic activity, faulting and deformation around Grindavk. Discussions focused on how geological information can be used to improve understanding of hazards affecting communities and infrastructure and on opportunities to investigate the poorly characterised offshore continuation of the recent fault and volcanic systems. The delegation also visited Carbfix’s facilities in Keflavk and HellisheiΓ°i, where researchers learned more about Iceland internationally recognised carbon mineralisation technology. Discussions explored future opportunities for knowledge exchange relating to basalt-hosted carbon storage and subsurface characterisation, including potential relevance to future developments in Scotland and elsewhere in the UK.

A key outcome of the visit was the identification of several future collaborative opportunities spanning marine geoscience, offshore hazard mapping, marine geophysical surveys, carbon storage, infrastructure resilience and geological characterisation of the Icelandic shelf.

The project was made possible through BGS membership of the Scottish Alliance for Geoscience, Environment and Society (SAGES), a partnership of Scottish research institutions that promotes collaboration across the environmental sciences. As a member organisation of RIS, SAGES provides an important mechanism for developing new international partnerships and collaborative research opportunities.

The visit demonstrated the value of international collaboration supported through RIS funding, helping create new connections between researchers and organisations with complementary skills and expertise. It also highlighted how Icelandic strengths in active volcanic and tectonic systems can be combined with BGS experience in offshore geological mapping, geotechnical characterisation and decision-support products to address shared scientific and societal challenges.

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New research by BGS, in collaboration with Durham University and the University of Dundee, shows that the shallow seabed of the North Sea is more geologically complex than typically represented in current cable burial approaches. The findings have important implications for how subsea cables are routed, installed and safeguarded from natural and anthropogenic hazards such as erosion, dredging and ship anchor strikes. 

Subsea cables are critical infrastructure arteries, transporting vast quantities of data between countries and connecting offshore energy developments to the UK mainland grid. Due to the nature of their environment and the water depths involved, installing and protecting cables is expensive and logistically complex. This is especially true in the shallow waters around the UK Continental Shelf, where the risk of damage from external hazards is highest.

The most common protection method for subsea cables is burial within the seabed. Widely used guidance such as standard cable-burial risk assessment typically applies simplified, single-soil assumptions that do not fully reflect real-world geological complexity. However, sea-floor geological environments are highly variable, ranging from fine sediments and gravels to shallow bedrock. These differences mean that burial conditions can change over short distances, requiring site-specific understanding rather than a one-size-fits-all approach. Increasing burial depth alone does not necessarily improve protection; deeper installations can significantly increase costs and may introduce additional risks, including overheating of the cable.

As part of an Engineering and Physical Sciences Research Council (EPSRC)‑funded project, β€˜Offshore cable burial: how deep is deep enough?’, researchers have produced a new, . This is the depth range that is critical for cable burial and protection.

The study integrates over 12 000 geological records from BGS archives and the Crown Estate Marine Data Exchange, providing the most detailed regional picture to date of shallow subsurface conditions across the UK North Sea. The results show that layered soils are widespread, with most sites containing multiple layers of different soil types, often with sand overlying clay, gravel, peat or shallow bedrock.

The findings challenge the simplified, single soil assumptions that current risk assessments commonly use and highlight regional contrasts throughout the North Sea. For example, the southern North Sea is largely dominated by surficial sands, whilst the northern North Sea is more geologically variable. Thin gravel layers are widespread, with thicker layers and shallow bedrock occurring more locally, particularly in nearshore areas where burial constraints are greatest. Although less common, organic rich soils and peat are shown to occur mainly beneath thin sand layers where they are not visible from seabed sediment maps alone.

These variations influence how the seabed behaves during cable installation and can influence burial approaches. For instance, depending on the burial method used, coarse layers such as gravels can naturally increase resistance to penetration, whereas finer sediments may require erosion defences to be considered. On the other hand, shallow bedrock or other hard layers may limit achievable burial depths altogether and therefore need additional protection.

Alongside the geological analysis, the project conducted advanced physical and numerical modelling led by the University of Dundee and Durham University, respectively. The research demonstrates how anchors interact with different soil profiles, highlighting the importance of realistic ground models for predicting cable performance and reducing installation risk.

Together, the findings provide stronger evidence for early stage cable-route planning and risk screening, and could help inform future updates to cable-burial approaches. By moving beyond simplified seabed classifications, the project enables industry and regulators to make more informed decisions about where and how deeply offshore cables should be buried.

Research by the 51ΑΤΖζ has been essential in defining the seabed conditions that must be considered when assessing the anchor‑strike risk to subsea cables. From a numerical modelling perspective, this project represents the culmination of 12 years of advancing the material point method (MPM)for large‑deformation soil/structure interaction. It has delivered a suite of robust, reliable and genuinely predictive modelling capabilities that go beyond what is possible with commercial software. We hope the project findings will advance current cable-burial risk assessments by allowing realistic variations in seabed conditions to be captured within the anchor penetration prediction part of the framework.

Prof Will Coombs, professor of computational mechanics in the Department of Engineering, Durham University.

Our work shows that layered seabed conditions are widespread and therefore represent a crucial consideration for decision makers. Improving how we represent and contextualise this variability is key to making better early-stage decisions about cable routing, particularly for more complex projects.

Catriona Macdonald, marine geoscientist, BGS.

From a physical modelling perspective, this project has enabled world-first research, including tracking models underground using wireless technologies. This allows us to better understand how anchors respond to geological complexity and real cable installation environments. This has enabled us to create important datasets and evidence to inform to the next generation of computer-based simulation techniques. Working with BGS has helped us frame our investigation to cover the real-world geological complexity of the North Sea.

Prof Michael Brown, Chair of geotechnical engineering at the University of Dundee.

The approach may also have wider applications in other regions exposed to more complex geohazards, including sediment mobility, submarine landslides, volcanic activity and seismic risk, supporting improved resilience of critical offshore infrastructure.

The , along with its accompanying modelling outputs, marks a key milestone in improving our understanding of shallow seabed conditions.It provides a foundation for future work on standardising offshoredata and improving cable-burial assessments across the North Sea and the wider UK Continental Shelf.

The UK Centre for Seabed Mapping (UK CSM), a group of over 30 public sector organisations with a shared commitment to collect and share high-quality marine data, will undertake a seabed mapping survey – CSM2026 – to explore and map the seabed along the UK south-west coastline.

Throughout the four-week survey, using cutting‑edge survey technology deployed from the Research Vessel Cefas Endeavour, a team of 26 scientists from across the field of maritime research will collect vital hydrographic, geological and environmental data when they set sail from Lowestoft next week.

51ΑΤΖζ marine geoscientists Dayton Dove and Duncan Stevens will be on board, with a primary focus on acquiring sub-bottom profiler (SBP) data. An SBP is a type of sonar system, emitting sound waves that both reflect off, and penetrate through, the seabed to image the shallow subsurface. Those that penetrate through seabed reflect off the geological layers and buried structures, providing 2D cross-sectional images of the subsurface. This data (and resulting subsurface maps) are required for many offshore infrastructure applications, and importantly also provide further information on the nature, composition, and stability of the seabed itself.

Convening multiple government agencies, the survey represents an unprecedented level of collaboration within the maritime sector. By combining their skills and capabilities in a single survey, the team aim to secure data to deliver the UK government commitments and make advances in how our seabed is mapped, understood and managed.

51ΑΤΖζ are one of eleven UK CSM member organisations, which also includes: the Maritime and Coastguard Agency (MCA); the UK Hydrographic Office (UKHO); Centre for Environment, Fisheries and Aquaculture Science (Cefas); Department for Environment, Food & Rural Affairs (Defra), The Crown Estate; Historic England; Joint Nature Conservation Committee (JNCC); Agri-Food and Biosciences Institute, Northern Ireland (AFBI); Natural England and the Royal Navy.

Over the course of the survey, the scientists on board will have the opportunity to work with experts from other public sector organisations, share skills, and source key seabed mapping data that supports a wide range of applications including offshore energy and infrastructure, marine ecosystem science, safety at sea, marine policy, and defence. The four-week research survey is due to take place between 20 April and 19 May. This will consist of two survey legs, starting in Lowestoft, Suffolk and ending in Falmouth, Cornwall. All organisations are supporting the planning of alternative sites to maximise the opportunity.

“This is the first time that such a large-scale, multi-agency, collaborative survey has been undertaken in the UK and it a really exciting venture. We are fortunate to have expert scientists and surveyors from across government who will collect a wide range of highly valuable data. The partnership approach provides opportunities to share knowledge and expertise, as well as providing invaluable training and offshore fieldwork experience.

β€œThe alliance of organisations is working together to increase efficiencies for data collection, processing and analysis under the gather once, use many times philosophy.

β€œSeabed mapping data provides the UK with a foundational basemap of its marine estate. Such valuable datasets are increasingly underpinning the maritime economy and energy security, enabling sustainable management of marine resources, development of marine policies and planning, and improves our understanding of the marine environment.”

Andrew Colenutt, Chair of the CSM2026 Project Team and Head of Hydrography and Meteorology at the MCA

“The UK CSM has proven to be an excellent forum for marine surveyors, scientists, and managers from across the UK public sector, increasing awareness, collaboration, and visibility of a disparate range of seabed mapping activities and applications.

This survey is an excellent opportunity for drawing the diverse expertise from across the UKCSM, and of particular significance for geoscientists, will include the collection of sub-bottom profiler (SBP) data. BGS has advocated for acquiring SBP data on hydrographic surveyors in order to provide crucial sub-surface data for a range of applications.

Scientists and decision-makers working in the offshore environment are reliant on high-quality seabed data to inform the siting, design, and installation of offshore infrastructure projects, such as Offshore Wind installations, habitat and ecosystem mapping, archaeology, marine aggregates, coastal erosion and management, and baseline geological and environmental science.”

Dayton Dove, BGS Marine Geoscientist

β€œThis joint survey is a fantastic example of what public sector collaboration can achieve when expertise, capability and purpose are aligned. By bringing together organisations from across the UK maritime sector through the UK Centre for Seabed Mapping (UK CSM), we are not only improving how the seabed is mapped, but deepening our collective understanding of the ocean environment, while also providing an opportunity for various experts to learn from one another.

β€œHigh‑quality seabed mapping underpins everything from safety at sea and environmental protection to sustainable development and supporting national security. Working together through the UK CSM allows us to maximise the value of data, share knowledge, and deliver insights that no single organisation could achieve alone”

Rear Admiral Angus Essenhigh OBE, UK National Hydrographer & Director of Data Acquisition at the UKHO and chair of the UK CSM Steering Committee

About the UK Centre for Seabed Mapping (UK CSM)

The , administered by the UKHO, was established in 2022 and coordinates the collection, management and access of seabed mapping data. Through collaboration, the UK CSM aims to improve understanding of the UK maritime estate and inform the effective management of marine resources. There are currently over 30 public sector organisations who are members of the UK CSM with an interest in marine geospatial information and data.

The 51ΑΤΖζ (BGS) 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 . 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 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, BGS 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: .

51ΑΤΖζ would like to acknowledge The Crown Estate as well as wind farm developers for contributing reports and data to The Crown Estate Marine Data Exchange.

For the first time, a science team has directly documented and extensively sampled a freshened water system beneath the ocean floor off the coast of New England in the USA. This major discovery comes from the initial analyses of sediment cores recovered during the , led by Co-Chief Scientists Professor Brandon Dugan (Colorado School of Mines, Golden, USA) and Professor Rebecca Robinson (Graduate School of Oceanography, University of Rhode Island, USA.

The 872 m of core, retrieved from deep below the sea floor, is now being opened, analysed and sampled by the science team, during almost a month of intensive, collaborative work. The expedition scientists are working side by side during January and February 2026 to uncover new insights into the formation, evolution and significance of this newly documented, sub-seabed, freshwater system.

Five BGS staff members are part of the operational team: Jeremy Everest, Margaret Stewart, Raushan Arnhardt (expedition project managers), Mary Mowat (database manager) and Bentje Brauns (hydrogeology). Their role is to coordinate and support the science team to process the core according to IODP³ standards and protocols.

The goal of this expedition went far beyond collecting sediment cores. Scientists also set out to sample the water stored within the sediments, including from sandy layers that act as aquifers and from clay layers known as aquitards that usually keep the water in place beneath the sea floor.

Although roughly 70 per cent of Earth surface is covered by water, significant volumes of water also move and are stored below ground. Many coastal communities depend on land-based aquifers for their freshwater supply. What fewer people realise is that, in many parts of the world, the aquifers continue offshore and contain zones of β€˜freshened’ water beneath the ocean floor. Scientists have known these offshore systems existed since 1976, but they have remained virtually unexplored until now. During the expedition, the science team successfully documented and sampled freshened water within a zone nearly 200 m thick below the sea floor.

We were excited to see that freshened water exists in multiple kinds of sediments – both marine and terrestrial. Freshened water in such different materials will help us understand the conditions that emplaced the water.

Prof Brandon Dugan, Colorado School of Mines, Golden, USA.

Further analyses, such as age models, conducted by the science team will help to find out where and especially when the water was placed here.

The cores contain sediment with a wide range of composition and ages. It was surprising to see sediment, not rocks, throughout the section. The sediment has not yet transformed into rock – I did not expect to see that and it will be an interesting component of our future work.

Prof Rebecca Robinson, Graduate School of Oceanography, University of Rhode Island, USA.

After a successful coring, sampling and downhole logging campaign last summer, the BGS team is incredibly excited to be supporting the science team to begin the scientific analysis the material collected. The cores have been safely held in their plastic liners since they were drilled out of the seabed and, at the Onshore Operation in Bremen, they are being opened and split, revealing the fresh split-core surfaces for the first time.

The BGS team are contributing to the detailed sampling and analysis of the cores that, when combined with the groundwater samples taken from the borehole, will improve our understanding of the development of the New England shelf and the freshened water reservoirs underlying it. It is such a satisfying moment, after years of effort to acquire the cores, to be rewarded with new data and insights in such an important and societally relevant subject.

David McInroy, marine geoscientist, BGS.

Shedding light on similar water aquifers around the world

The approach used during IODPΒ³-NSF Expedition 501 will not only deepen understanding of offshore freshened groundwater systems off the coast of New England, but will also shed light on similar hidden water aquifers around the world. Because many coastal regions rely on groundwater for their freshwater supply, the expedition initial findings are highly relevant to society. The research will also reveal how nutrients such as nitrogen cycle through continental shelf sediments and how these processes influence the abundance and diversity of microbes living in these environments.

These goals align closely with the 2050 Science Framework for Ocean Research Drilling – one of the foundations of the IODPΒ³ scientific programme. Ultimately, the expedition research will help to decipher how sediments and fluids cycle through the Earth system and improve our knowledge about sea level changes and freshwater flow beneath the seabed along our coastal shelves. β€œThe researchers will continue to work on and with the samples to decipher more – for example, to date the groundwater more accurately which is critical to advancing our knowledge,” adds Rebecca Robinson.

Background

The expedition is a joint collaboration between the International Ocean Drilling Programme (IODPΒ³) and the US National Science Foundation (NSF). The cores were retrieved during offshore operations between May and August 2025. For onshore operations the science team have met at the Bremen Core Repository, at MARUM – Center for Marine Environmental Sciences of the University of Bremen (Germany). β€œWe greatly appreciate being able to conduct this advanced research at MARUM, supported by its world-class laboratories, exceptional facilities, and dedicated staff,” adds Brandon Dugan

The cores will be archived and made accessible for further scientific research for the scientific community after a one year-moratorium period. All expedition data will be open access in the IODPΒ³ Mission Specific Platform (MSP) data portal in PANGAEA, and resulting outcomes will be published.

International approach

Forty science team members from 13 nations (Australia; China; France; Germany; India; Italy; Japan; the Netherlands; Portugal; Sweden; Switzerland; UK; USA) are taking part in this MSP expedition that consists of two phases: offshore and onshore operations. Offshore operations took place between May and early August 2025.

The expedition is conducted by the European Consortium for Ocean Research Drilling (ECORD) as part of IODPΒ³, funded by IODPΒ³ and the US National Science Foundation (NSF).

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51ΑΤΖζ 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 BGS Offshore Quaternary 250K datasetcomprises a compilation of legacy BGS 1:250000 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 1:250000 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 β€˜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 1:250000 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 BGS.