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.

In 2023, BGS entered into a data-sharing partnership with to enhance understanding of the seabed and shallow subsurface conditions across the United Kingdom continental shelf . The partnership granted BGS access to Ossian extensive survey data, with the development set to become one of the world’s largest floating wind farms.

In total the lease area covers 858kmΒ² and is located 84km off Scotland east coast. Once glaciated and now submerged at approximately 72m depth, the site offers a unique opportunity to investigate offshore stratigraphy and geomorphology in a region undergoing rapid environmental and industrial transformation. It also allows researchers to compare findings to Ossian parent company ’ other projects in the Firth of Forth: and .

As part of the project, BGS scientists hosted a dedicated workshop attended by members of the Ossian project team, which included a mini-field trip day in Midlothian close to the BGS office in Edinburgh. The field trip allowed the project teams to explore similarities to geological features found onshore and discuss the broader implications for interpreting offshore survey data. By examining glacial deposits, meltwater channels and till sequences in a terrestrial setting, geoscientists can refine offshore geological models and reduce uncertainty in infrastructure design.

A key example observed during the field trip was the heterogeneity of the sediments across relatively small areas, with notable variations in grain size, composition and depositional structure. These complexities mirror the variability of ground conditions found offshore and highlight the importance of detailed site characterisation when planning and constructing marine infrastructure.

To help contextualise the offshore data, the field trip explored several key geological sites in Midlothian, each offering valuable insights into glacial processes and sedimentary environments similar to those observed beneath the sea.

Auchencorth Moss: Black Burn exposure (Local Geodiversity Site)

Auchencorth Moss is an extensive, peat-covered plateau dissected by small streams and drainage channels. The , where a tributary joins the River North Esk near Penicuik, features an exposure of three distinct glacial tills with varying physical characteristics and compositions. Though partially obscured by slope wash and vegetation, the upper sections remain visible and accessible for study. The exposure reveals how glacial processes deposited and reworked sediments, which act as a useful analogue for interpreting stratified units offshore.

Carlops meltwater channel

There is a classic example of a subglacial meltwater channel systems at , a Geological Conservation Review Site and partially a Site of Special Scientific Interest (SSSI).

The bedrock-cut channels at Carlops exhibit braided forms, rock islands and chute features. These geomorphological structures help explain the beneath ice sheets, which are also evident in offshore channel features. The site also provides a good opportunity to emphasise the scale of channel features, helping to conceptualise the variability of the offshore landscape.

Hewan Bank

, an SSSI located close to Roslin Glen, presents a textbook sequence of two tills overlain by sands and gravels. The locality has been used to construct the regional glacial stratigraphy for the Edinburgh and Lothians area.

The debate over whether these represent separate glaciations or complex depositional environments mirrors the interpretive challenges faced offshore, where seismic and core data must be carefully analysed to distinguish between similar units. The wider Roslin Glen area, known for its meltwater gorge and incised meanders, also illustrates the erosional power of glacial meltwater and the formation of geomorphological features that can be traced in offshore bathymetry and sediment records.

Collaboration

The collaboration between Ossian, SSE Renewables and BGS provides important new data that is being used to update baseline geological models for the Central North Sea and the Firth of Forth. These feed into BGS publicly available offshore maps and datasets, which support a wide range of users including developers, regulators, researchers and marine planners. Integrating data from offshore wind farms such as Ossian with existing geological frameworks will help to guide future offshore developments and promote the sustainable use of marine resources.

This initiative also builds on BGS longstanding relationship with Ossian joint venture partner SSE Renewables and highlights the value of sustained collaboration in delivering large-scale renewable energy projects. The Ossian floating wind farm, which is a joint venture between SSE Renewables, and (CIP), is set to deliver up to 3.6GW of renewable energy, enough to power 6million homes and offset up to 7.5million tonnes of carbon emissions, marking a significant step forward in the UK journey to net zero.

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Catriona Macdonald
Margaret Stewart

Renewable energy infrastructure, whether on- or offshore, requires in-depth understanding and accurate characterisation of the underlying geology.  Developers increasingly need detailed geospatial observations of the seabed and shallow subsurface, which are critical to the siting and design of offshore infrastructure such as submarine cables and offshore wind turbines. This is certainly true in the Bristol Channel, which is home to the second largest tidal range in the world. This high-energy environment has attracted much interest around the use of the seabed for tidal power and the potential to produce electricity from wave energy.

To support policy- and decision makers in this region, BGS has released an enhanced seabed geology map of the Bristol Channel, almost four times the size of the original, which extends from Carmarthen Bay to Newport and further south to the coast of Somerset.

Beyond offshore infrastructure, these maps also directly contribute to understanding of marine ecosystems, coastal management and defence activities. The data provides crucial information to those ensuring the port facilities along this coastline meet the requirements for these development opportunities.

As the UK transition to renewable energy gathers pace, these maps will become increasingly valuable to industry and stakeholders with an interest in developing clean energy, from offshore wind to tidal streaming, and in carbon capture and storage.

The successful implementation of offshore renewable energy projects and technologies and the development of ports in South Wales require a detailed understanding of the seabed. This new, expanded, fine-scale seabed map of the Bristol Channel will be an invaluable resource for developers, providing access to high-quality, detailed observations of the seabed geology that is vital to these kinds of developments.

Beyond its critical role in supporting the renewables sector, the map will also be useful to other data users, such as those involved with supporting marine ecosystems, coastal management and defence activities. It will also provide evidence for policy- and decision makers in the region.

Rhian Kendall, BGS Chief Geologist for Wales.

The map, featuring combined bedrock, sediment, bedrock structure and seabed geomorphology data, is available from BGS under the fine-scale maps section of theand is designed to be viewed at 1:10000 scale, or online as downloadable shapefiles. For information on licensing the downloadable GIS data (ESRI format), please contact digitaldata@bgs.ac.uk.

Characterising the distribution of seabed sediments (SBS) is critical for a wide range of applications, including:

• habitat mapping
• marine ecosystem science
• mineral and aggregates assessments
• offshore infrastructure siting and monitoring
• defence
• shipping
• coastal management

51ΑΤΖζ has developed the new national-scale 51ΑΤΖζ Predictive Seabed Sediments (UK) dataset aimed at supporting these applications. The dataset comprises four digital maps that portray SBS composition, including a classified map of sediment types, as well as the predicted proportions of gravel, sand and mud across the UK continental shelf.

These detailed maps are based on about 40 000 sample measurements, as well as numerous physical covariates that relate to the spatial distribution of SBS. They were generated with the assistance of machine learning.

Understanding the nature of the seabed is fundamental for many offshore activities, from understanding benthic habitats and carbon stores to effectively designing and installing offshore infrastructure, including wind turbines and submarine cables.

Seabed sediments lie at the interface between the water column above and the variable geological substrate below. To an extent, they can be considered similar to the soil layer on land, but offshore sediments are exposed to dynamic marine conditions and are therefore potentially transitory and mobile over variable timescales, for example, during tidal, seasonal and storm cycles.

We hope that the release of the new BGS Predictive Seabed Sediments (UK) dataset will provide a useful free resource for many users, including researchers, developers and marine managers.

Dayton Dove, marine geoscientist at BGS.

The BGS Predictive Seabed Sediments (UK) dataset is now freely available to download under the Open Government Licence (OGL) and can be used in combination with other thematic 51ΑΤΖζ 250K datasets that are also now available via OGL, such as bedrock geology. It can also be used with our more recently produced, high-resolution seabed geology mapping.

The Joint Nature Conservation Committee provided initial co-funding and supported this project.

Seventy-four days offshore, 718 cores and 871.83 m of total core from three locations: this is the successful outcome after the end of offshore operations of IODPΒ³-NSF Expedition 501: New England Shelf hydrogeology. The goal of the expedition was to take samples not only of sediment cores, but also of the water stored in both sandy aquifers and clayey aquitards beneath the ocean floor. Their existence has been known for decades but they remained virtually unexplored β€” until now.

The expedition is a joint collaboration between the International Ocean Drilling Programme (IODPΒ³) and the US National Science Foundation (NSF), with the expedition being managed and technically supported by the team at BGS.

We set out with lofty goals of understanding the origin and age of this offshore freshened groundwater system through sampling of sediment and water in a difficult drilling environment consisting of sand and mud. With great teamwork between the science team, the technical staff and the drilling crew, we managed to get great samples, including via multiple groundwater pumping tests.

Those tests were a critical to the expedition and a first for scientific ocean drilling. And we did it! Now we have the samples for the science team to really dive into the data and understand the system, which will be helpful for understanding other offshore freshened groundwater systems around the world.

Prof Brandon Dugan, expedition co-chief scientist.

The pump tests were challenging and required us to adapt our processes to get the best possible samples of the groundwater. In the end we pumped nearly 50 000 litres of water from nine distinct places, in terms of location and depth below the sea floor.

This is a huge success story for something so novel. For me in particular, as a geochemist and not a hydrogeologist, I am so appreciative to everyone that leant their expertise. The team of hydrogeologists from the 51ΑΤΖζ especially was outstanding.

Rebecca Robinson, expedition co-chief scientist.

During the expedition, the science team rotated on and off the Liftboat Robert, transported by helicopter or supply vessel. The entire science team will meet for the onshore operations at the Bremen Core Repository, at the Center for Marine Environmental Sciences at the University of Bremen (MARUM), in January and February 2026 to split, sample and analyse the sediment cores and water collected. The cores will be archived and made accessible for further scientific research for the scientific community after a one-year moratorium period. All the expedition data will eventually be open access in the IODPΒ³ MSP data portal in PANGAEA and resulting outcomes will be published.

I’m absolutely delighted for our BGS colleagues and the whole expedition team, who have delivered this outstanding and unique project for IODP³. The sediment cores, water samples and logging data they helped collect will now be analysed by the international science team to better understand the New England continental shelf and its freshened groundwater system, and I expect some groundbreaking results will emerge in the months and years ahead.

David McInroy, BGS project lead.

International approach

51ΑΤΖζ scientists are part of a science team with over 40 members from 13 nations (Australia, China, France, Germany, India, Italy, Japan, the Netherlands, Portugal, Sweden, Switzerland, the UK and the USA) that takes part in the expedition. The expedition itself 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 the International Ocean Drilling Programme (IODPΒ³), funded by IODPΒ³ and the US National Science Foundation (NSF).

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