Wednesday, 20 September 2017

Work Experience at the BGS Stable Isotope James Setchfield

Hi, I’m James and for the past week I have been gaining experience working in the stable isotope facility at The British Geological Survey in Keyworth. I have a burning passion for Geography and the processes that help to shape and change the physical world around us. I am currently in sixth form doing my A-levels but have every intention of pursuing this subject to a degree and career level. The work experience scheme I was placed on helped me to gain an understanding of the career pathways Geography leads to. My week at BGS has allowed me to use and understand scientific equipment that I have only ever seen in diagrammatic form.

To start off the week we conducted an experiment with Chris Kendrick where we took samples of calcium carbonate (CaCO3) with unknown oxygen and carbon isotopic values and reacted them under a vacuum, with Phosphoric Acid (H3PO4). The carbon dioxide (CO2) we produced was transferred into a collection vessel, using liquid nitrogen to freeze the CO2, and any unwanted gases were removed using a vacuum pump.

This process took us 2 days so on Wednesday we had a sample that was ready to be put through the mass spectrometer. We learnt how to set up the mass spectrometer manually, which was very useful in enabling me to understand how the machine runs and produces data from the samples. Our samples needed to be left running overnight, so by Friday we had our data which showed us that the loch we were investigating changed from fresh water to marine water, which coincided with the glacial retreat at the end of the last glacial period. This showed us that as the glaciers retreat and the sea level rises, marine water floods the loch and changes the water composition and we were able to trace this using the different isotopic values for carbon and oxygen in our samples.

During our time at BGS we also conducted an International standard Mass Spectrometer Calibration which calibrates the mass spectrometer with all the others in different stable isotope labs around the world, this is to make sure the results  are to the same degree of accuracy and to make sure the data can be cross checked by different labs.

We also had a chance to speak to Dr Angela Lamb who carried out an investigation on the skeleton of Richard III. She was able to see what he had been eating throughout his life by looking at the carbon and nitrogen isotopes in his teeth (age 3-14) femur (17-32) and rib bones (30-32, when he was king). This was all very fascinating and made me want to find out more about how exactly they discovered what he ate and where he lived all through his life by looking at his skeleton.
On the whole I have had a very informative week working at BGS, it has really given me an opportunity to see what working in a laboratory is like and the type of investigations that go on, who knows maybe I’ll end up working for The British Geological Survey in a couple of years, all I can say is that I look forward to it.

Thursday, 14 September 2017

My work experience week at the British Geological Laura Wainman

Hi, my name is Laura Wainman and I am a sixth form student from Rushcliffe School. I have just completed my work experience week in the Stable Isotope Facility at the British Geological Survey. BGS is a world renowned geoscience centre with its headquarters here in Keyworth, Nottingham. A great variety of research is conducted at BGS, from monitoring and forecasting volcanic eruptions and earthquakes to studying local and global environments.  Along with another student James, I have spent my week learning how, from measuring the isotopes of oxygen and carbon, the climate and environmental conditions from thousands of years ago can be deduced.

On Day 1 (after the health and safety induction) we began our week long experiment to extract Carbon Dioxide (CO2) gas from Calcium Carbonate (CaCO3) samples which could then be analysed in a mass spectrometer. The first stage in this experiment was to weigh out our carbonate samples into small test tubes, drop these into larger glass vials containing phosphoric acid and then attach these to the vacuum pump (see above photo) so that overnight all the air could be removed. We then allowed the phosphoric acid and sample to mix by shaking the larger vessel and leaving it in a 25.2oC water bath overnight so that the reaction could be fully completed and all at the same temperature. The next day we then had to extract the CO2 gas which had been formed by the reaction. To do this we reattached the vessel to the vacuum pump and then used liquid nitrogen (which was at -196oC) to sublime the CO2 whilst we removed any other remaining gases.  The gas was also passed through an acetone water trap to remove any water which would have later damaged the mass spectrometer.

Once all of our samples had been extracted we then attached them to the mass spectrometer and left them to be analysed. It was especially interesting to learn in detail how the mass spectrometers work and see all of the components up close. I had not previously known about the use of a reference gas or the requirements of different machines to analyse different isotopes – the ones we were using looked specifically at Carbon-13 and Oxygen-18. On our final day we were able to collect and analyse our results, from the graphs we plotted we were able to see that the loch from which the samples were collected had gradually changed from a freshwater environment to a marine one. This was due to the increase in sea levels at the end of the last glacial period 12,000 years ago.

Whilst we were waiting for our main experiment to progress we were also introduced to many other areas of the lab. This included using microbalances, tweezers and mini spatulas to weigh out very very small amounts (70-150mg) of one of the BGS internal standards of freeze dried broccoli! Whilst frustrating at times, this has certainly given me a much greater appreciation of the meticulous and painstaking preparation of samples required to conduct good research.

We also helped prepare rock sediment samples from Vietnam and Tanzania for analysis, this involved daily emptying and refilling of (many) beakers in order to wash the samples of debris and dirt. Once the samples had dried out we then scraped them out of the beakers and used a mortar and pestle to grind them into a fine powder before depositing them into small vials ready to be analysed.

Monday, 11 September 2017

Rain, hazards and thin sections: A geological adventure in Sierra Lorraine Field

I have just had the opportunity to spend a week and a half in a very wet, rainy Sierra Leone, working with Kathryn Goodenough as part of a two-year partnership project, funded by the Department for International Development (DFID), that is focusing on building a lasting legacy around capacity in the extractives sector. Sierra Leone has been left reeling in recent decades with a brutal ten-year long civil war that finally ended in 2002, the recent Ebola Crisis, and now a catastrophic landslide in the capital, Freetown. My role in country was to run an introductory petrology course to some of the geologists in the National Mining Agency (NMA). Recently refurbished, the Agency has purchased two microscopes to enable them to study rocks in thin section. This is something we at BGS take for granted, but for the NMA, this will be a tremendous step forward. My first challenge was getting four boxes of thin sections that will form the core of a teaching collection at the NMA into country. According to UK customs, thin sections are an offensive weapon, and I very nearly had them confiscated! The flight was spent in nervous anticipation of arriving in Sierra Leone with four boxes of fragmented glass, but fortunately, the boxes survived the baggage handling intact!

A view of the microscope lab

We arrived in country following weeks of exceptionally heavy rain – one estimate we heard was that the rain in August had been 3 times greater than the norm – and believe me, when it rains here, it RAINS! It’s the first time I’ve had to give lectures and battle with the noise of the rain in order to be heard!

Heavy rain at about 10am at the NMA
Unfortunately, this proved to be a contributing factor in a catastrophic landslide in early August causing ~1000 deaths, and extensive destruction to property. BGS colleagues have been working with Arup and local consultancy Integems on a World Bank-funded hazard mapping project for Sierra Leone, and so Kathryn was invited to represent BGS at a World Bank meeting on arrival in country. This meeting brought together key players, to look at issues such as damage to infrastructure (e.g. roads and bridges), stabilising the landslide, hydrology, and obviously, the factors contributing to the cause of the landslide in the first instance. It was a fantastic experience for me to observe the processes and work involved with major organisations such as the World Bank and UN following such a disaster.

Over the weekend, we visited the landslide site with personnel from the international organisations, but also local staff from the NMA (which includes the Geological Survey of Sierra Leone) and members of the Sierra Leone Institute of Geoscientists (SLIG). The BGS project in Sierra Leone takes every opportunity to provide field training and experience to the younger geologists within the local organisations, by taking them into the field with more experienced geologists.  This was a very humbling experience – the news bulletins really did not portray the enormous size of the landslide, nor the reality of the damage caused. We were able to take a detailed look at the geology from the side of the landslide itself and provide our observations to the World Bank and associated organisations. I was grateful to have the opportunity to really see how our branch of science can play a fundamental role in a disaster situation, helping to understand the causes, and then working towards understanding future hazards and risks. We also collected some eyewitness accounts which provided invaluable insights into the timing of key events, and which really brought the reality of the disaster home to us. Freetown is a relatively small capital city of just over 2 million people, so in such a small community everyone knew someone who had lost their life in this disaster.

A view of the landslip from near the source with some of our colleagues from the NMA and SLIG
The petrology course at the NMA started on Monday, with an intense week of lectures and microscope practical sessions. A colleague from the University also joined us in order to refresh and re-stimulate his knowledge. The delegates were eager to learn and proved to be A* students. We worked through an incredible amount of material, from basic microscope operation to covering identification of minerals and textures in sedimentary, igneous and metamorphic rocks in thin section. It was an absolute delight to be able to teach delegates who were so enthusiastic. I hope by the end of the week that I had been able to achieve the aim of providing a foundation that the NMA staff can build on and develop through experience, and then pass on this knowledge by training more staff themselves. I hope soon they will be able to characterise the thin sections that are currently sent out of country for characterisation by the mining companies, thereby growing a commercial service in country at the NMA. As well as working hard, we had an enormous amount of fun during the week: the people of Sierra Leone have a wonderful, fun loving disposition, and one of my most endearing memories of this country will be that of mischievous laughter! If anyone is interested in becoming involved in the BGS work in Sierra Leone, please contact Kathryn Goodenough.

Friday, 1 September 2017

My first field season: rocks, bubbles and low-cost technologies... by Jo Miles

Hi, my name is Jo and I began my PhD at the British Geological Survey and School of Earth Sciences, University of Bristol in September 2016. My research aims to further our understanding of preservation potential of mineralising systems located in the shallow submarine environment (<100 m). In this blog, I will share with you an aspect of my field season on the Greek island of Milos from this summer.

Dynamic submarine processes can help or hinder preservation, potentially resulting in either a bonanza or a failed ore deposit. Therefore, it is important to understand the dynamic processes and the preservation potential, to determine whether the shallow submarine environment is prospective for future mineral exploration and exploitation. The island of Milos, located in the Cyclades, Greece, provides an ideal on-land laboratory having emerged 1.4 million years ago. The island’s topography reflects the paleo-seafloor, and allows us to directly study and sample mineralised and hydrothermally altered paleosurfaces that formed in the shallow submarine environment.

I have recently returned from my field season where we drove approx. 2000 km (a similar distance from Nottingham to Rome) around winding roads of a 13 by 23 km island over a period of five weeks. The first challenge of the trip included learning to adapt to a Jimny Jeep that was not happy to be in first gear or reverse.

I was joined in the field by my main supervisor, Jon Naden, for a handful of days prior to the rest of the party. This was a great opportunity to visit mineralised and altered outcrops, which I had only read about in literature. This was vital in helping my understanding of hydrothermal systems and begin to visualise how my PhD project will pan out. More students from the University of Bristol and Ottawa shortly joined us for a week, alongside researchers from the University of Athens - the island was certainly busy.  

One aspect I am keen to research involves how mineralisation differs from the western ancient hydrothermal system in comparison to the active system located in the east. In order to observe the active submarine environment and witness the potential ore-forming environment, we collaborated with PhD students Jonathan Teague and Dean Connor from the School of Physics, University of Bristol, whom have experience building and deploying low-cost remotely operated underwater vehicles (ROVs) and unmanned aerial vehicles (i.e. drones; UAVs). With knowledge from the University of Athens, we deployed a BlueROV2, equipped with a GoPro Hero 5 off the southern coastline of Milos Island. This was entirely controlled via a laptop and Xbox 360 controller onshore, which allowed the ROV to move a maximum distance of 100 m offshore.

1. Setting up the office for venting exploration.

2. The ROV in action.

The aim of this pilot study allowed us to decipher the location of active venting fields – were they randomly dispersed or was there a structural or permeability control? Knowing the NW-SE horst-graben structural control on the island, we inferred this lineament out to the southern coastline. Alongside rotten-egg smelling fumaroles located in the cliff faces, we were able to decipher two likely venting locations to deploy the ROV. The rotten-egg odour is indicative of sulfur in the form of H2S: a gas coming directly from an underlying magma chamber.

Three days were spent identifying and undertaking reconnaissance mapping within an area of 1 km2 where we successfully found venting sites. The team from the School of Physics, University of Bristol undertook a Structure-from-Motion (SfM) photogrammetry program, to produce high-resolution 3D topographic reconstructions of the seafloor. Thousands of images taken with the GoPro Hero 5 contribute to a handful of bathometry models. Despite the huge volume of data, this is a much cheaper option.

3. Locating bubbles with the ROV via laptop control.

Since the vents are relatively shallow (<7 m), we returned to the area during the evening to snorkel which was the perfect treat to end an incredibly hot day hiking to outcrops. Luckily, the sun was still shining, which meant the visibility conditions underwater were perfect. Often, you could use your sense of smell to locate the venting fields. Patches where bubbles were rising often resembled the temperature of a hot bath (approx. 60oC). We avoided swimming directly over these areas due to the corrosive nature of the escaping gases.

Unlike the ROV, we had to be patient with the weather in order to fly the drone. Rain and strong winds often set us behind schedule. For safety purposes, a team of four was needed: two would secure the location to prevent the public from being close to the flight area, whilst the pilot and computer-operator would liaise to ensure the drone was following the pre-planned flight lines. We chose terrain-challenging locations to create photogrammetry models, which would enable remote fieldwork with a 10 cm resolution.  When discussing my research and its implications back home, it will now be much easier for the audience to follow my thinking if I display the landscape and rocks to them, as if they were on fieldwork with me.

4. UAV Pilot undertaking a test survey.
This was a great opportunity to be part of a student-led research project with a diverse range of skillsets, with the full backing of our supervisors. We are currently writing our first paper and eager to develop the project further and revisit the venting site next spring.

My supervisory team consists of Jon Naden (BGS), Frances Cooper and Brian Tattitch (University of Bristol), Stephen Grebby (University of Nottingham), Dan Smith (University of Leicester) and Graham Ferrier (University of Hull).

Jo can be found on Twitter using the handle @geologyjomiles

Photography credit:  Jonathan Teague,

Thursday, 31 August 2017

Learning geology and promoting BGS's OpenGeoscience at the OUGS Festival of Gemma Nash

The BGS stall set up ready to receive visitors.
On Friday 18 October, I packed my car full of BGS flyers, goodies and specially created OpenGeoscience posters and headed over to the Queen Margaret University on the east of Edinburgh for the Open University Geological Society (OUGS) Festival of Geodiversity.

I didn't know what to expect, but was greeted by some very friendly OUGS organisers and set up a BGS stand in a break out room opposite the main lecture theatre for the weekend's talks. I was sharing the space with BGS's Don Cameron who is the OUGS secretary and was selling some of BGS's published books.

I was there to promote the new data that is available via OpenGeoscience and found that the Festival's demographic were particularly interested in our newly available Publications and Maps Portal. I also had a lot of interest in testing the new version of our iGeology app.

As a web developer whose knowledge of geology has only been absorbed during my eleven years working for the BGS, I was surprised quite how much I understood at the three talks I attended over the Friday and Saturday and and how much new geological knowledge I obtained. The other delegates were very keen to share their learning and experiences which complemented the lectures.

From L-R: Tim Kearsey presents 'Evolution of life on land: how new Scottish fossils are re-writing our understanding of this
important transition'; Maarten Krabbendam presents 'Origins of the Torridon and Moine in the foreland basin of the
Grenville Orogen'. 
BGS's Tim Kearsey and Maarten Krabbendam both presented and were very well received. Maarten described how the Moine and Torridonian rocks are actually intertwined over Scotland and Canada. Tim talked about the TW:eed project where four-legged animals Tiny (Aytonerpeton) and Ribbo were discovered as our Scottish ancestors.

On the Monday, I was lucky enough to be invited on a field trip to Siccar Point and Cove, south of Dunbar.Our trip leader was Angus Miller from Geowalks who described the local sedimentology and geological periods as we walked along the top coastal path near Cove.

From L-R: Angus Millar and his dog Roxy providing scale for Hutton's Unconformity;
Cove Beach surrounded by Old Red Sandstone cliffs. 
Then we trekked over to Siccar Point and I was mesmerised. Not only is the scenery beautiful, but I felt privileged to be standing on arguably the most important geology in the world, where James Hutton proved the world was millions of years old. Angus explained that the eroded Old Red Sandstone that was layered almost at right-angles to the Wacke below shows that these sediments were laid down at different times; about 65 million years apart!

We ended the trip with a picnic on beautiful Cove beach which is only accessible by a slightly creepy and dimly lit sandstone and brick tunnel. On the beach we found lots of evidence for the Anthropocene in the form of beautiful pebbles of beach glass. We then discussed how the sedimentary rocks that formed part of the harbour wall contain features that enable you to decode different river processes that laid down the sediments over time.

Monday, 28 August 2017

Mud, mud and more mud: salt marsh sampling in Essex... by Helen Brooks

Hi, I’m Helen and I’m a 1st year PhD student at the University of Cambridge, in partnership with BUFI, the BGS University Funding Initiative. My research looks at sediment properties of salt marshes and tidal flats and how these relate to the stability of salt marshes. This means I get to spend a lot of time sampling in the field, which is great fun (if the weather is good)!

Why are we interested in salt marsh stability?

Salt marshes help protect the land behind them from flooding and erosion, however marsh areas are declining globally. My research will improve models that simulate future marsh evolution, particularly in a changing climate. This will help us to understand whether marshes will continue to protect us from flooding in the future.
Sunset on Tillingham marsh in February
What exactly do I sample?

I’m interested in the sediment properties and how these relate to erosion resistance. During my PhD I hope to look mainly at the sediment shear strength, compressibility, shrink-swell behaviour and plasticity (i.e. how the sediment behaves at different moisture contents). Most of these tests will be done in the lab and will require undisturbed samples. That means a sample where we try to keep in the in situ condition. For anyone who hasn’t done undisturbed sampling before, you’ll probably think I’m crazy by the end of this paragraph. I’m going to try and explain the process of collecting the samples. Essentially, you dig the outside of a pit, leaving the central section untouched (see photo). Then you carefully remove the vegetation and the uppermost sediment (and by 'carefully' I mean 'using small kitchen knives to remove 2 cm2 chunks of sediment, bit by bit'!). The next step is to place the sampling equipment on the surface, push down gently by 1-2 mm, then scrape the excess 1-2 mm of sediment carefully from around the side of the equipment (see photo). Then we repeat pushing down and scraping the excess sediment until the sediment reaches the top of the sample! In total, digging the pit and taking the sample can frequently take three hours! Finally, the samples are wrapped in A LOT of bubble wrap, placed on trays and packed in boxes to reduce disturbance during transport! But after all this, do you know what the best part of the day was? Enjoying a glass of freshly squeezed orange juice! To explain: the rest of my research group were in the field flying a drone over the marsh and used halved oranges as ground control points (novel, I know!). However, so as not to waste the oranges, these were squeezed before we went out to the field!
Digging the outside of the pit, leaving the central section untouched.
Carefully pushing the sampler into the sediment, then scraping away the sediment around the outside. This particular sample is nearly done, as the sediment inside the sampler has now reached the top of the sampler.
 Where do I sample?

Most recently, I was sampling at Tillingham Marsh in Essex. We spent two days meticulously taking undisturbed samples in the glorious sunshine (though unfortunately it isn’t always like this!), before carefully transporting the samples back to Cambridge. The samples were taken from the lower marsh, close to, but not on, the tidal flat.

Tillingham Marsh in summer
What next?

I’m now about to start work on these samples at BGS Keyworth. This will involve three weeks of more sample preparation, plus lots of loading the samples into machines which allow me to assess properties such as consolidation, shear strength and shrink-swell behaviour.

If you’re interested in finding out more about my project, please follow me on Twitter at @hbrooks94 

Friday, 25 August 2017

Pebbles, photography and... glycerine? The BGS through the eyes of a newbie... by Grace Davis

Grace Davis started work at the British Geological Survey in July 2017, in this weekly series she shares what she gets up to as part of the Comms team at the BGS...

Pebbles: small, round, found at the beach. They’re not things that get a lot of attention really, although I expect most of us have felt the small satisfaction of gripping a particularly smooth one in our hands or skimming a lovely flat one across the waves.

I’ve found myself considering pebbles a lot this week, and that’s all down to the Comms team’s new Pebble Project! We decided that these little over-looked geological items deserved a bit more attention so we’ve gotten to work on designing some pebble resources. Aimed at all ages, these downloads will be available for people to take out and about – use them at the beach to identify what you’ve found, use them as the basis for a fun project (there are a surprising number of things you can do with a pebble!) or use them to learn more about the different rock types around the UK.

Our resources are currently still in the creation stage, with a very glamourous pebble photo-shoot taking place today. As you can see in the (exclusive, first-look!) images, we took photos of the pebbles both wet and dry. This is simply because wetting pebbles can often bring out beautiful detail that you just can’t see otherwise. If you’ve a pebble on hand, give it a go and see!

Sandstone pebble

And now I’m going to let you into a little trick of the trade: the wet-look here is achieved not with water, which would dry too fast under the studio lights, but with glycerine! By the way, I do hope you’re building up a nice mental image of this photo-shoot – i.e. me hunched over a tray of sand, feverishly rearranging pebbles and getting increasingly grittier and stickier as I slather them in glycerine!  
The same pebble with added wet-look!

So, do look out for updates on the Pebble Project in the near future, including where you will be able to get hold of the resources. Until then you can find our existing information about pebbles (as well as our other great holiday geology guides) on the BGS website, here. And don’t forget, if you’re interested in resources for learning about geology, at whatever level, you can visit our online shop here or come and see us in our shops in Keyworth, Edinburgh and London.  

Sadly not dragon eggs, but rather beautiful limestones!

That’s about all from me this week, but join me again next time as I continue to learn and share all about the (amazingly varied!) work of the BGS…

Wednesday, 23 August 2017

Rambling on the Rocks: Around Northern Ireland in 20 Kirstin Lemon

Advert for the walks guide in NI4Kids.
Northern Ireland is one of the most geologically diverse places on Earth. As a geologist, I am very lucky to live here as I can pretty much drive to anywhere in under two hours, and therefore 'visit' every single geological time period in a day. I spend a great deal of time telling people about rocks (as part of my work I mean, not just to random people in the street) and one of the best ways to do this is to lead a guided walk. That way I can show people what to look at and help them to understand why the natural landscape looks the way it does, but of course I can't be everywhere at once...

Landscapes from Stone

At the Geological Survey of Northern Ireland (GSNI) we have a long history of producing popular geology publications. Some of our most successful were the Walk and Explore guides produced as part of the EU-funded Landscapes from Stone project. But these were published in 2000 and many of them were out of date so GSNI decided it was time to produce a new walking guide, taking the best bits from the original Walk series and making sure that we covered the whole of Northern Ireland.

A new walking guide

The long process of producing the new walking guide began back in 2012 when I first started as Landscape Geologist with GSNI. Using my knowledge of Northern Ireland's geology I identified areas to focus on that would not only cover the country geographically but also take into account as much geological diversity as possible. After going through the original Walks series, a number of walks were selected that would best represent particular features, were in especially scenic areas, or were well-known walks in their own right. I also identified many additional walks that I knew of either as a geologist, or as a lover of the outdoors, and put the whole list together.

The selection process

All of the walks were tried and tested either by me, or by some of our work experience students who were only too keen to get out of the office for the day. Each route was meticulously mapped, photographed and detailed notes were made about what to see along the way. Many of the original walks were scrapped as they were simply not there any more and some of the others had to be changed or added to ensure that there was good access and that there was enough to see and do. In one case, the original route took me through a river that went up to my thigh!

View from Cave Hill, one of the two walks in Belfast.
Image from Tourism NI.
A team of us at GSNI eventually whittled down the walks to 20, including three in every one of Northern Ireland's six counties, and two in Belfast to highlight the fact that you can still see geology even in the city. We included walks that were suitable for serious hillwalkers including one that takes you to the peak of Slieve Donard in the Mourne Mountains, and walks that are suitable for families with small children such as the one around the kettle lakes at Lough Fea in Co. Tyrone.

Useful information

Ballykeel Portal Tomb on the Mullaghbane Walk.
Image from Ring of Gullion AONB.
One of the major additions was that I wanted to make sure that the book was useful and didn't just tell you where to walk and what to see. Each walk has information on where to park, where the nearest town is, where you can get refreshments (because every good walk should end with tea and buns), where the nearest public toilets are, and in some cases what public transport you can use to get there. I also included what walks are suitable for who, and provided information on what walks are suitable for pushchairs and for dogs, a serious consideration for many walkers.  

I tried in many cases to use walking routes that are already in existence and that are way-marked. This way it saved on the directional instructions in the book and allowed more time to talk about what you see along the way. Aside from the geological heritage, I included other aspects of heritage in each one to try and encourage walkers to appreciate the links between geology and well, everything!

Time for a geological 'journey'

The book has been written for the popular audience as we want as many people to use the book as possible. I tried to include all of the major geological attractions in Northern Ireland such as the Giant's Causeway, but I also included places that non-geologists might not know about such as Barnes in Co. Londonderry and its spectacular glacial landscape. This has all been accompanied by stunning photographs as there's nothing more likely to make people pick up a book that an amazing image.

The ultimate aim of Rambling on the Rocks is to get as many people out walking and exploring the natural landscape of Northern Ireland as possible. I want to ensure that every time they use the book that they are taken on a geological 'journey' and one that I am fortunate to go on every time I go walking.

'Rambling on the Rocks: Walking Northern Ireland's Natural Landscape' by K. Lemon, M. Cooper and A. Donald is available to buy directly from GSNI and is also available at the BGS shops in Keyworth, Edinburgh and London with an RRP of £7.99.

Friday, 18 August 2017

In a jam: the impact of geology on the Stonehenge tunnel Andy Farrant

The mention of Stonehenge often conjures up visions of standing stones and druids, but more often than not traffic jams also spring to mind. As anybody who has driven along the A303 in summer will know, the road past Stonehenge is a regular bottleneck. Traffic flows regularly exceed capacity and impacts one of the most iconic sites in the UK. In 1995, Highways England put forward proposals for a cut-and-cover tunnel to bypass Stonehenge. This was rejected following protests about the impact on the archaeology. New plans for a 2.1 km tunnel were drawn up in 2002 with an estimated cost of £183 million — before the impact of geology was assessed.

Like many other major infrastructure schemes in southern England, the tunnel was scheduled to be excavated in Upper Cretaceous Chalk. To the uninitiated, Chalk may appear to be a relatively homogenous flinty white rock, but to a geologist or engineer it is anything but. Its composition varies a great deal, ranging from soft clay-rich chalk without flints to very hard nodular chalk with abundant flints. The Chalk is also a major aquifer, the name given to a permeable rock that contains groundwater, so tunnelling can be problematic, especially where faults or major flint bands occur or where there are soft, weak or weathered chalks.

Ground investigation

When ground investigations started at Stonehenge in 2001, the most relevant up to date BGS geological map was from 1903. This showed the whole route as being underlain by ‘Upper Chalk’, which is not much use for developing a ground model or predicting engineering properties of the chalk! Site investigation boreholes were drilled along the tunnel route to understand the geology before tunnelling. In the Chalk, identifying key features such as flint bands in borehole cores and sections is an essential first step in understanding the ground conditions. Correlating these markers helps identify geological structures such as faults and helps tunnellers to predict difficult ground conditions.

Initial logging of site investigation boreholes by Prof. Rory Mortimore (Chalk Rock Ltd) proved ‘normal’ white chalk with flint bands, but one borehole indicated the presence of an unusual deposit of phosphatic chalk. Further ground investigations recorded the thickest known phosphatic chalk deposits in England with several horizons of phosphatic chalks and hardgrounds separated by ‘normal’ white chalks with flint bands and marl seams.

Geological mapping

In 2003, BGS remapped the Salisbury 1:50,000 sheet including the area around Stonehenge as part of the BGS national geological mapping programme. The ‘Upper Chalk’ is now divided into four formations: the Lewes Nodular, Seaford, Newhaven and Culver Chalk formations. The geological mapping confirmed the presence of the phosphatic chalk channels and identified several faults and fold structures. The very weak sandy phosphates occur within the upper part of the Seaford Chalk Formation, and the channels are overlain by the Newhaven Chalk Formation. We were able map out the main axis of the phosphatic chalk channel which extends for almost 2 km southwest of Stonehenge. The mapping was assisted by the use of high resolution palaeontology provided by Mark Woods and Ian Wilkinson. More recent fieldwork earlier this year confirmed the spatial extent of the Newhaven Chalk infilling the channels. The data was used to construct a geological cross-section along the proposed tunnel route.
Map of the area around Stonehenge 

Impact of geology on the tunnel scheme

The discovery of these phosphatic chalks had a major impact on the proposed tunnel scheme. The weak sandy nature of the phosphatic chalk, and the identification of several zones of weathered or faulted chalk influenced the design of the proposed tunnel and the machinery required to excavate it. The possibility of radon gas from the potential radioactive minerals in the phosphatic chalks and the risk of groundwater contamination were other environmental considerations. Disposal of phosphate-rich tunnelling spoil also posed a problem as it was likely to impact local vegetation.

The nature of the geology and groundwater conditions led to construction costs to more than double from £183 million to an eye watering £470 million! On 20 July 2005 the tunnel scheme was withdrawn by the Government partly due to rising costs of construction.

New tunnel scheme

In January this year, the Transport Secretary, Chris Grayling announced a new proposal for the Stonehenge bypass including a 2.9 km tunnel to the south of the initial scheme at an estimated cost of £1.4 billon. The preferred route is to be announced this summer. BGS mapping suggests that this new tunnel will also intersect phosphatic chalk. Geology matters…

Further reading 

Details of the geology of the Stonehenge area based on the site investigations for the 2002 tunnel scheme and BGS mapping have just been published in the Proceedings of the Geologists' Association.

Andy Farrant is the regional geologist for SE England

Monday, 14 August 2017

Stable Isotope Mass Spectrometry User Group (SIMSUG) Meeting…by Jack Lacey

In July, the 14th Stable Isotope Mass Spectrometry User Group (SIMSUG) meeting was hosted by the Stable Isotope Facility at the British Geological Survey. SIMSUG brings together scientific users, engineers, manufacturers, and suppliers of mass spectrometry equipment to discuss new applications and developments in stable isotope research and analytical instrumentation. Although the meeting has been held annually in the past, the last SIMSUG was hosted six years ago in 2011 by Lancaster University Centre for Ecology and Hydrology – so about time for a catch up!

Over 80 delegates attended this year’s meeting representing many disciplines and affiliations, including UK- and EU-based universities, research institutes, academic journals, and mass spectrometry companies. The meeting kicked-off with a tour of the BGS, including the geological walkway and core stores, and the stable isotope, geochronology, inorganic and organic geochemistry facilities, highlighting the broad range of geoscience, health, and environmental research undertaken at the BGS.

Delegates of SIMSUG 2017
The meeting programme was diverse, with scientific talks and posters organised into overarching themes covering methodological advances and systems innovation, tracing terrestrial and marine palaeoenvironmental change, and palaeodietary studies. Dr Peter Wynn (Lancaster University) gave a keynote presentation discussing the relevance of subglacial methane generation in a warming world, and Dr Tamsin O’Connell (University of Cambridge) described the contribution isotope analyses have made to palaeodietary studies and the potential for future developments.

A conference dinner was held at the National Justice Museum where delegates were able to enjoy an informative and interactive tour of Nottingham’s historic courthouse and jail. Dinner was followed by a guided walk through the city.
Discussions continued over dinner at the
National Justice Museum

Congratulations to all PhD students who won prizes. The quality of the presentations and posters was very high indeed and all student presenters received commendation from the judges, Peter and Tamsin. The award for best overall presenter went to Benjamin Bell (University of Manchester), best talk to Hal Bradbury (University of Cambridge), and best poster to Kim Wood (SUERC). Well done everyone!

Thanks to our sponsors (Thermo Fisher, Elementar, Sercon, Elemtex, Isoanalytical, Goss Scientific, Elemental Microanalysis, QRA) and to the rest of the Stable Isotope Facility organising team. Catch up with #SIMSUG2017 on Twitter!

We hope to see everyone again at SIMSUG 2019, which will be hosted by the Life Sciences Mass Spectrometry Facility at the University of Bristol.

For more information on SIMSUG, please visit the group’s Facebook page.