At over 1000 km long and 40 km deep, the Great Glen Fault is the largest geological fault structure in the UK. As part of ground investigations for SSE Renewables’ proposed pumped hydro storage scheme at the Coire Glas site on the shores of Loch Lochy in the Highlands, deep drill core was extracted from beneath the Great Glen. BGS scientists were granted a unique opportunity to study the newly drilled fault rocks that are part of the Great Glen Fault Zone. These ‘first of their kind’ core samples have lived up to their billing, with experts claiming that they give unprecedented insight into the inner workings and behaviour of crustal-scale faults worldwide.

The Great Glen Fault formed around 400 million years ago in a massive mountain-building event, as the ancient continental plates ofÌýLaurentia (North America and Scotland) and Baltica (Scandinavia, England, Wales and Europe)Ìýcollided. This tectonic event is known as theÌý. The fault stretches from Ireland, all the way through Scotland, to Norway. Today, the fault underlies the major valley of the Great Glen, which crosses the whole of Scotland and was scoured out by glaciers during the last ice age. Generally, rocks associated with the Great Glen Fault Zone remain mostly hidden to the human eye by the waters of Loch Ness, Loch Oich and Loch Lochy, along with ice age deposits along the valley floor.

The new drill core from the Coire Glas Project offers the tantalising prospect of furthering our understanding of how these fault systems work and how fluids emerging from deep within the Earth crust change the properties of the rock. Over 1500 m of core were recovered, reaching depths of 650 m below ground level. Core was drilled on the shore of Loch Lochy and from within an underground tunnel at the base of the mountain. Drilling geological core is expensive and is normally only justifiable to such extensive depths as part of major energy or infrastructure projects. The added difficulty in relation to the Great Glen Fault is that, in addition to being located in remote parts of the Highlands, fault rock can be very weak and presents a technical challenge to drill successfully.

The new geological samples provide an opportunity to understand the geological processes happening deep in the Earth crust. This is also relevant for understanding other major crustal faults, such as the San Andreas and Anatolian faults. Several key questions remain:

• does this fault connect all the way to the Earth’s mantle, thought to be at more than 30 km depth?
• what is the source of fluids in crustal fault zones?
• how do hot fluids interact and change the mechanical properties of the rocks in a fault zone?
• how many times has the fault moved in its long geological history?
• how have the hundreds of earthquakes that likely made the fault zone changed the properties of the rock?

I have had the privilege to study the first samples of these Great Glen Fault rocks using state-of the-art microscope facilities at BGS. Our findings give strong clues as to how ancient deformation processes and fluid/rock chemical reactions caused the fault to initially weaken associated with displacements of hundreds of kilometres. Remarkably, it then appears to have been cemented following later tectonic movements that channelled deeply sourced carbonate mineralisation. Much more remains to be discovered, but it is clear that these cores have the potential to elevate the Great Glen Fault to one of the great natural laboratories for fault zone studies worldwide.

Professor Bob Holdsworth, Durham University

Newly drilled core from the Coire Glas site has provided a unique opportunity to study fundamental geological processes occurring in the UK biggest fault zone. The storage of the Coire Glas core at BGS will allow access for the scientific community and will ensure that these rocks are preserved for future generations.

Romesh Palamakumbura, BGS Geologist

SSE Renewables is delighted to support the advance in scientific understanding of the Great Glen Fault and similar structures worldwide, thanks to the core that was recovered during the ground investigation for Coire Glas.ÌýAs well as being of scientific value, the recovered core has been critical for understanding ground conditions and managing ground risk as the project progresses towards a final investment decision.

SSE Renewables

The Coire Glas core will be stored and made available for future research purposes at the 51ÁÔÆæ National Geological Repository, a bespoke facility that is publicly funded through 51ÁÔÆæ and houses the UK foremost collection of geological samples. This will enable long-term preservation of the core, allowing scientists to study and attempt to unlock its secrets long into the future.

The core has the potential to help us answer fundamental geological questions about the history of the Earth as well as better understand major crustal-scale faults in seismically active regions elsewhere. It will also enable us to understand rock properties that are important for major renewable infrastructure projects, energy storage and geothermal targets. These cylinders of rock truly are one-of-a-kind windows back into our distant geological past.

In a warehouse just outside Nottingham, vast racks of geological core are carefully curated and stored in climate-controlled conditions. Part of the collections held within BGS National Geological Repository (NGR), this core is quietly energising the UK’s economy, supporting the nation growth agenda and energy transition aspirations.

Understanding our subsurface environment requires both direct observation, through samples such as drill core, and indirect observation, through sensors and monitoring. These observations are the basis on which we build models that constrain and test hypotheses explaining the Earth, its composition and its many processes. Such knowledge is critical for determining how society is affected by or can safely interact with the ground beneath our feet.

Saving cost, reducing risk and accelerating project timelines

Drilling new core is expensive. The cost of drilling just one new offshore borehole can be in the region of £20 to £30 million, around 20 times more than the annual operational costs for the NGR. Access to existing core can therefore significantly streamline the process for new infrastructure projects; it allows both public and private sector project managers to plan with a greater degree of certainty and better mitigate risk. More informed planning can result in drilling fewer new boreholes and a shorter project timeline. This not only saves significant costs; it also reduces any associated environmental impact.

Digital scanning has unlocked new opportunities … with limitations

Digitisation of rock samples and core is a powerful tool for the modern-day geologist. Improvements in analytical techniques, including core scanning and 3D imagery, allow cores to be re-studied and preserve a record of the original material prior to sampling. These advancements are providing scientists with better opportunities to investigate changes in physical properties such as porosity (the free space inside a rock that fills with fluids).

An array of scanning technologies, including X-rays and hyperspectral imaging, allows scientists to extract more data than ever before from samples. Collectively, this data, sourced from different analytical techniques, can be compiled into digital geo-specimens that enable exciting opportunities through machine learning and artificial intelligence tools. However, there is a cost associated with scanning and digitisation. With the size of the core archive, these activities need to be targeted to deliver the largest benefit to the UK.

Although geological observations and digital samples have significant long-term value, they are limited by the context in which they were collected and the technologies available at the time. Discarding physical samples after digitising risks losing the ability to re-examine them with new techniques and technologies as they emerge in future. Digitisation enhances the samples, makes them more discoverable, and increases their value, but is not a replacement for holding physical specimens.

Safeguarding for the future

What society needs from the subsurface changes over time. The academic and commercial relevance of core varies and does so in ways that can be hard to predict. Many of the reservoir cores from the Southern North Sea gas fields, which were drilled in the 1960s and 1970s, are now being re-studied to assess their potential for carbon dioxidestorage. Sites that were once prized for their coal reserves are now being revisited for geothermal potential. These uses were almost certainly never envisaged when the core was originally drilled.

In some cases, the core may be unique and irreplaceable, especially where land has since been developed or reclassified (for example, as a Site of Special Scientific Interest). Maintaining a reference library of boreholes enables future research to take place using new techniques, saving time, reducing costs and limiting the environmental impact. Crucially, it also supports reproducible and repeatable science.

Physical space within the NGR is always a consideration. It is not possible to retain every specimen we are offered. Material is selected based on its value to inform the geological record. Sometimes, materials may be discounted or discarded where there is an abundance of material from a particular area or where samples have deteriorated, but such instances are rare. BGS is actively exploring funding opportunities to expand this national facility, so that we can continue to ingest materials critical to the UK economy.

Over the last two decades, it is estimated that the NGR has saved the UK economy at least  Â£1.5 billion in avoided drilling and analysis costs alone. The importance of this facility can only increase as we maximise the potential of geological ‘super regions’ for renewable energy technologies.

As demand for natural resources grows and the effects of climate change intensify, so does the need for geological data to address the economic and societal challenges. All indications are that the most important phase of the NGR is yet to come.

The National Geological Repository (NGR) is a gateway to our shared subsurface. It is the UK most comprehensive collection of geological materials, consisting of over 16 million specimens and assembled over 200 years. The collection acts as both an evidence base of previous scientific endeavours and a resource for new and future research. 

The economic analysis shows that the NGR saves major energy and infrastructure projects significant costs through access and re-use of pre-drilled rock core:

• £1.5 billion in avoided drilling and analysis costs for major energy and infrastructure projects over the last 20 years
• Up to 36 times return on investment based on costs of maintaining the facility
• Time-savings of around three years per infrastructure project through access to legacy core samples
  

These returns are underpinned by the high costs of drilling new boreholes. It can cost more to drill an onshore borehole than run the NGR for a year and this can rise by a factor of 20 for offshore drilling.

Located at BGS headquarters in Keyworth, the NGR is home to the UK largest core storage and examination facility. Of particular value to industry and infrastructure projects are over 600 km of pre-drilled core from around the UK, which provide considerable cost and time-saving benefits.

“The BGS’ core facility (the National Geological Repository) is invaluable in enabling researchers to use legacy geological materials and data for new purposes in the transition to low-carbon energy.�

Gary Hampson, Professor of Sedimentary Geology, Imperial College London

“These cores were acquired at significant expense (often multiple hundreds of thousands of pounds per core) from offshore wells, specifically targeting areas of fundamental uncertainty in subsurface geology. Their preservation offers substantial economic and environmental value, as the cost of re-sampling or drilling new cores is prohibitively high. Moreover, the carbon footprint associated with new drilling can be significantly reduced by utilising these existing core samples for further research and decision-making, aligning with sustainability and Net Zero ambitions.�

Nick Terrell, Industry Co-Chair, Subsurface Task Force

The facility is trusted by government, regulators and industry to enable faster, better-informed decisions and is poised to enable UK clean energy infrastructure projects, including geothermal and carbon capture and storage.

As well as quantifying the impact of the NGR, the report also highlights a series of constraints that could limit the facility ability to deliver increased public value in future. Expansion will be required to accommodate further core acquisitions. This is vital as many present-day drilling operations are occurring in areas with potential for net zero technologies or mineral prospectivity, meaning the opportunity to re-use the core is high. Further potential lies in digitising the collection, as only a fraction of the physical holdings has been digitised to date, limiting the facility ability to deliver comprehensive remote access.

51ÁÔÆæ is exploring investment opportunities to secure and enhance the NGR long-term future and national value.

October 2023 saw BGS National Geological Repository (NGR) welcome two UK-based artists who were visiting the collections as part of their individual projects focused on the Blackwater Estuary in Essex. Nastassja Simenski and Angenita Teekens visited the repository to view core samples from around Bradwell A, a Magnox-design nuclear power station located on the Dengie peninsula at the mouth of the River Blackwater in Essex. The power station has been in long-term decommissioned management since 2019.  

The landscape of the Blackwater Estuary

Nastassja Simenski, artist and researcher at University College London, is studying for her PhD on the potential of collaborative fieldwork between artists and archaeologists. She is particularly focused on how the development of place-specific and collaborative methods ‘in the field’ enable new ways of highlighting current conversations around energy production in the Blackwater Estuary.  

Visiting the BGS repository and seeing the core samples from the Bradwell and Blackwater Estuary helped me to get a sense of how the geology of the area has shaped the landscape over time and, in turn, impacted the types of human production and interaction here over long durations […] for instance, the core samples from Bradwell are a starting point from which we can think about how a seemingly remote part of the Essex coast is implicated in wider contexts like managed realignment and climate change mitigation, agricultural policy, natural and cultural heritage, and the development of new forms of energy production.

Ìý

Nastassja Simenski

Natassja research includes place-based art practices and considers how specific scientific research and data such as BGS core samples can be used creatively to tell bigger stories that move across long time periods and wider geographies. The issues explored in her research are mediated through art including the potential to use data, historical records and interviews to inform musical scores, live performances and films that get shown in situ or in galleries, broadcast on radio and screened at film festivals. Natassja research includes place-based art practices and considers how specific scientific research and data such as BGS core samples can be used creatively to tell bigger stories that move across long time periods and wider geographies. The issues explored in her research are mediated through art including the potential to use data, historical records and interviews to inform musical scores, live performances and films that get shown in situ or in galleries, broadcast on radio and screened at film festivals. 

Earthworks: boreholes and dorodangos 

is an established artist with 25 years of experience in facilitating environmental community art projects. Her most recent project, ‘Earthworks’, is a community inquiry about bore samples, extraction, disposal and the energy transition. The project will see members of the Othona community, as well as community groups in Essex, creating 260 dorodangos, which will be twinned with bore samples taken from fields adjacent to Bradwell, which are currently stored at BGS.

The Japanese dorodango artform consists of a small sample of clay rolled into a sphere by human hands within human time, as part of a slow meditative practice.  

Accessing the BGS collections is a vital source of information for the creation of a borehole catalogue as part of Angenita project. The inclusion of visual materials such as borehole logs, along with sketches, drawings and writing, will help to guide participants in their creation of the dorodangos, whilst questioning land use, energy production, geological and human time and human impact on land. 

The National Geological Repository at BGS

The National Geological Repository (NGR) is a  and the largest collection of geoscience samples from the UK. It forms an integral part of BGS (part of 51ÁÔÆæ ) and is located at the BGS headquarters in Nottinghamshire. 

NGR unique collections are used extensively by industry, in research and to support university teaching. It has the UK largest core storage and examination facility, with the Core Store and records collections at its centre. The collections include: 

• borehole cores and samples 
• fossils, rocks and other samples 
• related subsurface information from the UK landmass and continental shelf 

About the artists

 

First and foremost, I’m Patrick and studying chemistry, geography and maths at A Level. For a week in July 2023, I was on work experience at BGS. I’ve had a passion for geology since I was brought to the Keyworth site for BGS open days, and I’m now intending to pursue a career in the subject.

The theme for week followed the journey of a borehole through BGS, which led to engaging with many areas and activities, including:

• a tour of the National Geological Repository (aka the Core Store)
• an introduction to 3D scanning of fossils with Simon Harris, the collections conservation and digitisation manager
• digital borehole logging and some 3D modelling with Steve Thorpe, a geospatial data specialist    
• meetings with members of communications team — Lee, Penny, Jade and Michael
• chatting with PhD student Ellis Hammond about his research on new digital tools to help speed up the redevelopment of brownfield land
• an introduction to the Core Scanning Facility and digital borehole data with petrophysicist Mark Fellgett

The borehole journey through BGS starts with sinking a borehole into the ground using specialised rock coring equipment. Borehole depths can range from 5 to 5000 m into the ground, each one providing unique insights into the world beneath our feet. A special drill bit is used to collect a core of the rock, which is then extracted, packaged up and transported back to the National Geological Repository at BGS Keyworth, where it registered.

The rock core is logged during a visual inspection of the different rock layers present in the sample. Many of the borehole logs and cores at BGS are from before the age of computers, handwritten on paper from as early as the mid-1800s. These older, handwritten logs are currently being converted into digital logs, with further scans being taken of the paper copies. They can then be input into software to build 3D models of the subsurface or used to create large-scale maps of the geology below our feet.

The core is then scanned, photographed and tested to gather data on its properties. For example, gamma rays can be used to test the density of a rock, P-waves can be used to measure the porosity, and X-rays, infrared spectroscopy and some chemical tests develop a picture of the rock properties.

Borehole data is being used to inform the transition to net zero. BGS researches the properties of rocks and the subsurface environment to work out if they can be used to store large quantities of carbon dioxide (CO₂) emissions from industry and power generation. This area of applied research is called carbon capture and storage (CCS) and the technology is a means of reducing the amount of CO₂ that is released into the atmosphere.

CCS is the process of injecting CO­₂ under high pressure (so it is more like a liquid than a gas) into porous sedimentary rocks in areas such as old oil or gas fields, which are then filled with salty water. Boreholes are key in deciding which areas are suitable for CCS, as they allow scientists to work out which rocks can store CO₂, how much CO­₂ they can hold and whether it is likely to escape in the future. 

Boreholes are also used to access geothermal energy present underground, for example using the water from abandoned mines. This water can store plenty of heat, depending on a range of factors. The water is pumped up to the surface where the heat can be extracted and used to provide a sustainable heat source. This reduces the need for CO₂-producing fossil-fuel power plants.

All in all, my week at BGS has been valuable in demonstrating the fascinating research that occurs here, and the broad range of skills that people need to conduct it. It has given me plenty of motivation to aim for a career in geology. nassive thank you to Dr Darren Beriro for organising my visit and to Steve Thorpe and Mark Fellgett for looking after me on a day-to-day basis.

The Critical Minerals Intelligence Centre (CMIC) has completed scanning a subset of the Mineral Exploration and Investigation Grants Act (MEIGA) reports that are held at BGS. These reports represent the records of 267 mineral exploration projects carried out in the UK between 1971 and 1984 (NERC, 2023). The first batch of scanned reports is now available to access on the .

MEIGA was funded under the former Department of Trade and Industry (DTI) through grants for mineral exploration of non-ferrous metals, fluorspar, barium and potash. This scheme resulted in significant new discoveries and developments, including the Gairloch copper–zinc–gold deposit, the Parys Mountain copper–lead–zinc deposit and the Hemerdon tungsten–tin deposit (Minerals UK, 2023).

CMIC is delivering the MEIGA reports in a geographically searchable, online and free-to-access format. The release of these reports will aid those assessing the UK prospectivity for critical minerals. They complement the report on the ‘Potential for critical raw material prospectivity in the UK’ produced by CMIC and BGS (Deady et al., 2023).

Although these have been available in hardcopy on demand, in view of the new UK Critical Raw Materials Strategy we thought it was timely to scan and release the data now. It provides an excellent opportunity to reassess previously collected data at no cost to the user.

Eimear Deady, BGS Economic Geologist.

The MEIGA reports contain:

• geological mapping
• soil and stream sediment geochemistry data
• geophysical surveys
• drill core logs
• assay data

The geological material collected in the 1970s and 1980s is available for viewing at BGS through the core store booking process and available online on the , where anyone can explore the MEIGA areas.

CMIC works closely with the Department of Business and Trade, which funds CMIC, and this data supports the Government Critical Minerals Strategy by providing accessible historical information to companies wishing to explore the UK critical mineral potential (BEIS, 2022). Accordingly, this release plays an essential role in supporting a more secure energy transition to net zero carbon emissions by 2050.

The geographical distribution of the MEIGA areas and associated reports can be viewed on the BGS GeoIndex, which holds a wealth of additional information from historical exploration campaigns conducted by BGS and industry. This includes borehole records, earthquake data and interactive 3D maps.

• Learn more about the GeoIndex

As a sector-leading organisation,Ìýthe 51ÁÔÆæÌýEnvironmentalÌýSustainabilityÌýStrategyÌýaimsÌýto achieve net zero carbon for our directly managed estates and research in line withÌýthe commitment made byÌýour parent body,Ìý51ÁÔÆæ. By 2040, we will have substantially raised our standard for environmentalÌýsustainabilityÌýand we will have fully embedded it in our scienceÌýstrategy and estate management. We alsoÌýplan to work beyond compliance.Ìý

The research we undertake and how we support it has an impact on the environment. It is essential that we understand this impact so that we can minimise our footprint and and transition to a more sustainable organisation. The commitments within our strategy are embedded across three areas: our estate, working practices and business travel.

In order to meet the net zero targets highlighted in our strategy, we are reducing our demand on fossil fuels by installing the most environmentally friendly modern technologies on our sites. Carbon dioxide (CO₂) levels are substantially higher now than at any time in the last 750 000 years. Burning fossil fuels releases CO₂ and other harmful greenhouse gases, which then accumulate as an insulating ‘blanket’ around the Earth, trapping more of the Sun heat in our atmosphere.

Our latest renewable energy project entailed the installation of a large solar panel array on one of our largest roof spaces at the Keyworth site, the National Geological Repository (Core Store). An incredible 1751 photovoltaic array covers a massive 3100 m² area of our Core Store Facility’s roof. This array will result in 589 165 kWh of electricity being generated per year — the total yearly energy consumption of around 160 UK homes — and will save an estimated 305 776 kg of carbon each year.

By installing solar panels, the BGS Keyworth estates team has utilised a system that could be installed relatively quickly and would make a key difference on our estate. Generating our own electricity via solar energy means we will be emitting less CO₂ into the atmosphere, reducing our carbon footprint and increasing our sustainability credentials.

We look forward to sharing futher renewable energy initiatives at BGS in the near future.