BRGM took part in the Science Festival organised all over France from 8 to 16 October 2016.
26 October 2016

The French Geological Survey (BRGM) was one of the 15 scientific partner organisations of Science en direct (Live science) held on 8 and 9 October 2016 at the Cité des Sciences et de l'Industrie in Paris. Open to the general public, this entertaining free event aims to arouse people's curiosity about science.

Presentation: "Safeguarding Heritage"

"Safeguarding heritage - using isotopes to characterise works of art", a presentation by Wolfram Kloppmann (BRGM) (Paris, 8 October 2016).

© L'Esprit Sorcier

When science meets the arts, when science serves to protect or explore our heritage... That's not a science people often talk about. And yet, when you look into it, it's obvious that you use high-technology, almost futuristic things. Let's find out about it with Wolfram Kloppmann. For me, the BRGM, is a large French institution that maps the substratum and knows what's going on. You work at the Louvre, where you look into the origins of the alabaster used to sculpt some extraordinary works of art. First let me ask you: what is alabaster?

The thing is, it isn't disconnected from of geology. It's a geological material. So alabaster... This is a pretty piece found only last week in the French Alps. All fresh.

So what is it? Some kind of gypsum?

Absolutely. It looks like marble but it isn't. It's the noble version of gypsum. Gypsum is used to make plaster. Alabaster is hard and fine enough to sculpt.

So it's something you don't have to dig too deep for? It can be skimmed off?

Absolutely. It can be found on the surface. Actually, it's more common than marble, especially in France. It was often used instead of marble, even in prestigious sculptures, i.e. statues of kings, popes and cardinals. So it's a noble material, used throughout the Middle Ages and even in ancient times. Probably because when polished, the stone sparkles, as you can see on the pictures. It's extremely smooth.

Also very alive. Marble is often perceived as cold, a little too bright. This produces a surface that's closer to human skin. So there it is. Another aspect is, you can work it with your nails. You can scratch it.

So it's fragile for a sculpture that's meant to last for centuries.

It is, but afterwards, it acquires a surface patina which protects it, but it's much easier to work than marble.

Amazingly, this stone, in very thin layers, is transparent. It is translucent. We sometimes see vases made from it and the light passes through.

It does indeed.

So let's return to the scientific side of things. Your goal is to examine statues at the Louvre, and try to ascertain where the alabaster comes from and from what period.

Absolutely. In the history of art - not in the case of Egypt, which has a famous history - the further back in time we go, the less we know about the sculptors, about the artists. In the Middle Ages, it's difficult to put a name to a sculpture. We know what Rodin sculpted but here it's much more difficult. We don't know who did the sculptures. We don't necessarily know where the studio is and we don't know the provenance of the material used for the sculpture. If we can answer this last question, or make some assumptions.... If we know, for example, that the alabaster is English, it may have been made in an English workshop. So that's one of the goals of this study, carried out by a multidisciplinary team.

A scientific police investigation to find the artist.

In a way, it is. It's not a crime... It's prettier than traces of blood. We work with a team of historians, art historians from, among other places, the Louvre Museum and the Saint-Quentin museum. Also with geologists and people from the historical monuments labs. At the BRGM, we work on a certain type of characterization which helps identify things. The first objective is to find the source and maybe have an idea about the origin of materials and thus the workshops. The other issue, once we have made these links, is to realize that it had to be transported from quarry to workshop. So we are retracing the pathways of medieval commerce. That's very interesting, not just in terms of art history but of history as a whole. Knowing it was transported over great distances, along rivers, etc, gives us an idea about the medieval economy.

In purely scientific terms, what are your investigative tools? Isotopes. Is that it? Tell me.

Two pieces of alabaster, viewed from afar, are white. Up close, it's white too. Up close, mineralogical analysis indicates gypsum. Chemical analysis reveals calcium sulfate, with very few traces. So chemically, optically, we can't distinguish it. This is the problem with alabaster. So we used a much more sophisticated technique, which uses the actual elementary composition. We use isotopes: the isotopic composition of the alabaster.

Tell us how.

You have carbon. You all know carbon. Carbon 14, for example. In carbon 14, the number 14, signifies an isotope of carbon. The common carbon you find throughout the universe, 98% or more of it is carbon 12. Carbon 14 is a little heavier, hence its radioactivity and its usefulness in dating. You have, for each element, different isotopes, which are pretty heavy. We try to measure this mass using mass spectrometry. For each element, there's a relationship between heavy and light isotopes. In here, you have sulfur, oxygen, and a little strontium. We use the isotopic composition of these 3 elements to produce a fingerprint for these alabasters. We examined the quarries and compared our results to the isotopic composition of the sculptures.

You bring the two together.


What results have you obtained so far?

We suspected that, historically, a great deal of French alabaster came from England. England was a big exporter of alabaster until 1550. Any religious representation within churches was forbidden by the English Parliament. That was a real blow to alabaster production in England. Historically, we knew that. For other alabaster sources, our hypotheses were very weak. What we found is that a great deal of the alabaster analyzed in the Louvre and the Petit Palais d'Avignon, taken from statues of 14th century popes and cardinals, comes from a small quarry in the French Alps.


Which was notable for producing very high quality alabaster and also having access to a river.

For transport?

Exactly. So together, these two assets enabled the quarries of Notre-Dame-de-Mésage supply alabaster throughout the east and south-east of France. A map began to emerge. Then we looked at hydrography, flow network, rivers and watercourses to see where it went.

So you identify a quarry, but if materials are transported by river, the task of finding artists and workshops isn't any easier.


You've managed to find artists and sculptors?

We are beginning a new phase of this project with the Louvre, trying to solve some riddles in the history of art. We have a genius sculptor, the Master of Rimini. We don't know his name. There were hypotheses in the past. He may have spoken a Germanic tongue, maybe he's Italian because his works are in Italy. We now think it's more likely he's from Holland or Northern France. If we knew that his workshop always used the same material, that came, say, from England, we could actually say he worked in the Netherlands, a country England exported to. So now we are trying to trace sculptors, some known, some unknown. We'll work on Tilman Riemenschneider, a sculptor well known in the Germanic world. We're on the track of these historical puzzles and the history of art.

What's so fantastic about your experiments is that this technology, developed for science, is being used for something it wasn't meant for at the outset. Don't you agree?

It can even be used in the modern world. Some counterfeiters are talented enough to produce works of art that look extremely faithful to ancient works. A British museum bought some apparently Egyptian alabaster sculptures - this is what links our two studies - from the time of Akhenaten. They turned out to be fake. This was after the purchase and their expert assessments. This technique allows us to identify restorations and fakes. Because he probably worked with Italian material.

OK, well, our thanks to the BRGM for that explanation, and for conducting investigations and solving puzzles pertaining to our heritage, our culture, and the arts. Thanks for talking to us.

"Manip" forum: 3D visualization of the subsurface of La Réunion

"Manip" forum, "3D visual rendering of the entire subsurface of La Réunion" presented by Guillaume Martelet (BRGM) (Paris, October 9, 2016).

© L'Esprit Sorcier

Another exciting experiment, this time with Guillaume Martelet, a geophysicist at the BRGM who works on 3D scanning of Reunion Island's substratum. Guillaume, why examine the substratum? People visit Reunion to go to the beach!

Yes, the beaches are popular in Reunion. But there are problems underground too, which is why we are here. One of the main missions of the BRGM is knowledge of the substratum in terms of its uses. Obviously, it's extremely important. So why Reunion? Because it is a small territory - an island - which imposes many restrictions. It has a growing population, its needs are increasing, so the stakes are high on these small territories. In fact, Reunion isn't the first such territory we have flown over. We did the same with Mayotte, Guadeloupe and Martinique over the last 3 years. It's no coincidence.

"Fly over" is a carefully chosen term because you look beneath the surface from a helicopter. We have some images we can display while you explain... You examine the underground from the air.

- How does that work?

- It's surprising.

What we do is... It's comparable to the imaging used in medicine. In order to see what's going on in the human body, we use imagery, radiography, MRI, etc. In geophysics, we want to see the substratum without necessarily digging holes. So we use geophysics.

How does that work from a technical viewpoint?

Geophysics can be used at ground level as well as from a distance, either from aircraft or helicopters. In Reunion Island, helicopters had to be used on account of the relief. We couldn't do a flyover in a plane. What's more these methods have to be implemented at low altitude, just a few dozen meters above the ground. Obviously in a landscape like Reunion's...

How is it done? A helicopter with equipment attached is flown 10m above the ground?

No, 10m is a little low. But yes, we attach to the helicopter a loop, a kind of gondola. You'll see it in the pictures. The gondola carries 2 instruments, because this particular project calls for both an electromagnetic and a magnetic method. We'll talk about it later.

Tell us about the methods. You try to pick up signals?

In terms of magnetism, we measure a natural field, meaning the Earth's magnetic field, which varies on the surface and varies according to the nature of the rocks below. With this method, the instrument allows information to be gathered in a passive way. The 2nd method is the electromagnetic method. Here, a signal is sent from this device, which interacts with rocks in the substratum and sends back a signal which varies depending of the nature of the substratum.

Rather like a sonar.

Sonar is a geophysics instrument.

Right. So when you fly in this helicopter, what exactly do you see? I think you've brought along an image.

I can...

It's colorful! What are these colors? This is Reunion Island.

As you can see, it was flown over, since the whole map is colored. This is the result of one of the two methods: an aeromagnetic map of Reunion. The colors are a way to provide information, to render the information. Here, we will restore the magnetic properties of the substratum. Basically red indicates stronger magnetization, while blue indicates weaker magnetization.

How do you interpret this magnetization? What do these pretty colors mean? It's lovely! But what does it tell us?

This data... has a rather scientific use. The magnetization of the rocks tells us about alternations, particularly with regard to lava flows. Reunion is a volcano. Throughout its geological history it has had flows of volcanic material which settle and acquire a degree of magnetization depending on when they were formed.

So there's a scale.

Precisely. This allows us, cartographically, for example, to pinpoint certain zones, seen here in red, which correspond to the most recent. Conversely, the blues zones indicate rock from an older period. A layer system, indicating which came first and which ones followed. So what we see... is the result of all these layers. It looks flat.

I think your software allows us to read it in relief.

Indeed. I'll leave the map.

No, we'll remove it.

Yes, we need the big screen. Actually, what I'm going to show you, is the result of electromagnetism rather than magnetism. But the principle is the same. The idea is to produce information in 3D on the nature of the substratum.


So here we have the southwest of Reunion Island... St. Louis. St. Louis, Pierrefonds... this area. Here you see the Saint-Etienne River. As I zoom out, it doesn't go flat. We see it in 3D.

The same colors we saw earlier.

Yes, it's a geophysicists' thing. We love colors! Let me show you a couple of things. Here, you have... In 3D... This is the resistivity parameter, i.e. the ground's resistance to current conduction. We can see here that the resistivity of the substratum... Bear in mind that this represents a thickness of 200 or 250m. So it isn't very... We see the surface of this block. If I now... We can see the inside of the block...

What did you do? You selected natural layers?

No, I produced cross-sections. I sliced it. As I said, it works like a scanner that gives you cross-sections of the brain.

Here we are producing cross-sections of Reunion's substratum. It might seem a little strange... So what do we see?

For example, this is an aerial view. You see the coast, right?

The blue is water?

Seawater contains salt and conducts electricity very well, making this tool extremely useful in studying what is known as saline intrusion: i.e. the seepage of sea water beneath coastal aquifers. So one of this technique's applications is trying to see the movement of water in the substratum. In this case, we don't see movement, we see the geometry of the saltwater table forming in the substratum. How important is this? Very because the people living above pump freshwater, and these freshwater tables - this is physics! - sit above the slightly heavier saltwater tables. It's essential to know how thick the freshwater table is because obviously if you pump too much, you'll start getting saltwater. So this tells you exactly where the saltwater is.

To conclude, one last question. I'm curious to know about other applications for this tool.

This tool allows us to examine a number of issues related to the substratum in its first 200m. A lot of questions. We mentioned saline intrusion but anything related to water resources, geological imagery, with regard to underground aquifers... Anything to do with the presence of materials, including rocks: what types of rock, their hardness...

Everything that's going on in terms of density, soil quality...


And all the uses of that information.

- Thank you.

- My pleasure.

Full-duplex broadcast with Morocco on climate change

Full-duplex broadcast with the Cadi Ayyad University in Marrakech – organised with the help of Moussa Hoummady (BRGM) – concerning scientific cooperation between France and Morocco in the field of climate change, in preparation for COP22 (Paris, 9 October 2016).

© L'Esprit Sorcier

I'm delighted to welcome Moussa Hoummady. Hello. You're president of the Alliance Avenir France-Maroc, a scientific cooperation alliance. You are also head of Strategy, Forward Analyses and Partnerships at the BRGM, the French Geological Survey. Let's discuss the cooperation between our two countries, seeing as this year's COP... The COP is a major international summit that addresses climate change issues. Last year it was in Paris. That was COP21. This year, COP22 is in Marrakech. So this is a handover.

Absolutely. We wanted, on the occasion of this 25th Science Festival, to also mark the handover of COP21 to COP22, which promotes scientific and technical cooperation and addresses tomorrow's societal challenges.

Scientific cooperation with Morocco dates back to the 1960s, does it not?

Yes. The BRGM in particular, as well as other bodies, initiated this cooperation many years ago. In the BRGM's case, it dates back to the 50s or 60s, when the very first hydrogeological maps of Morocco were made by Jean Margat, who did a lot of work on water and climate change issues.

The aim was to see the water sources, to find them, wasn't it?

Absolutely. One challenge facing society is water management and usage. With climate change, water resources and water systems will be very affected. Water-related research, water system research, is crucial for arid countries and will be for us too.

Is this cooperation ongoing?

Yes. Since the first projects and hydrogeological maps, this work has been continued by dynamic teams on both sides of the Mediterranean, with the support of the International Association of Hydrogeologists. Its French section has 40 members, 23 of whom are French and 17 Moroccan. When it comes to the water issue, France and Morocco work very closely together. There's going to be link-up shortly. Everything is working, but we're waiting. Is there a time difference with Morocco?

Yes, one hour.

It's Sunday after all! We'll just wait patiently. We're discussing cooperation in the sphere of water but there are so many cooperation programmes between France and Morocco, in lots of scientific fields. In agriculture too.

Absolutely. As well as the issue of water systems, cooperation programmes exist in the field of scientific and technical instrumentation. There are training programmes too. The aim being to train up Moroccan technicians and engineers. So there's a regular transfer of skills. And Morocco is a good place for experimenting things that can't be done in France. The geology is different and permits such experiments. We've chosen the topic of water and water systems in relation to climate change, but there are many cooperation programmes. Most organisations in France have programmes with Morocco. I'd like to mention Orleans University and the CNRS...

Excellent! Let's talk about that before we speak to the president of Marrakech University. A cooperation programme is being implemented between Orleans University and Rabat University.

That's right.

What does it entail?

The setting up of an observatory to measure persistent air pollutants, which are climate change indicators. It's a new programme so I would like to discuss it in the TV link-up.

Here goes then. They must be online. Mr Abdellatif, are you there? We're delighted to see you.

So are we.

Excellent. You're on a big screen at the Cité des sciences et de l'industrie in Paris. Moussa Hoummady and I have been discussing the long cooperation between Morocco and France in the field of science. We would like you to tell us a bit more about it, Mr President of Marrakech University. Can you hear us?

Yes, I can hear you perfectly. Welcome to Marrakech. Even if you're not here! The architecture you can see gives you a fair idea.

We'll be over soon.

For COP22.

Marvellous. You must come and visit the university then. We're participating actively in COP22.

We certainly will. There's significant cooperation between France and Morocco. We have been discussing all the research relating to geology and water.

The relationship between France and Morocco, in all sorts of different areas but especially in research and higher education, has been symbiotic for a very, very long time, thanks to our common history and the ties developed between the personnel of our two countries. Just to give you an idea of figures, almost 70% of Cadi Ayyad University's research publications are with universities of the French-speaking world, and France in particular.

Gosh, 70%?

70%, yes. And this cooperation has existed since our university was founded 40 years ago, with the involvement of French research professors who have moved here, especially in the exact sciences. As for water, materials science, and biodiversity research, all the laboratories have been co-managed, co-created with French universities.

And now your university is expanding its research into sustainable development.

That's right. It has always undertaken it, it has always worked on issues relating to the mining sector and tourism infrastructure, with extensive research on water, energy and materials. And in recent years, the concept has really grown. We have developed an aspect called the Smart University project, which incorporates the sustainable development and social responsibility of the university.

I imagine it's a theme about which your students and young people will become increasingly aware, because of COP22.

Yes. COP22 is key. The spotlight is on this event. But the university has already tackled sustainable development and will continue to do so. Sustainable development and climate change are addressed in all disciplines, be it in teaching or research. Even the university's everyday actions incorporate this aspect now.

How many students are there at your university? Could you tell us about your university?

At Cadi Ayyad University, there are 82 000 students. Maybe a bit more. Enrolments are not yet finalised. But at least 82 000 students.

82 000?

That's right. Compared with other Moroccan universities, it is not the largest, but it comes top in all the international rankings. It has been Africa's top French-speaking university in all international rankings for the past 3 or 4 years. Our university has built up considerable research activity. It has been the backbone of all development since its foundation.

It must be very nice to be a student in Marrakech. I envy them.

I have a question, Mr President. Are you also involved in the promotion of science and technology among young people and the general public? It's a major issue for today's and tomorrow's societies. So it'd be interesting to hear about that too.

Yes, of course, like all universities. But we're fortunate to be in a cosmopolitan city, and we obviously use all of our contacts to try to popularise both. We have set up a lecture series that is very well known in Moroccan university circles and beyond: the Tribunes of Marrakech. With this series of prestigious lectures, we are doing our bit to promote understanding and awareness of science among young people. As well as this, there are initiatives at the university such as Science Week and Creativity Week. And now we have Sustainable Development Week. All of these programmes help raise awareness and understanding among young people. We consider that the age of our students is the best age to ensure these future adults will be socially responsible citizens.

Will your students be involved in some way in this upcoming event in Marrakech, in COP22?

Absolutely. They even have a side event. They have created a Science Caravan, which will soon be going around the city. They are very active. And we are helping them to communicate the message themselves. It's important for the young to address the young. We have some very active students.

Excellent. I imagine it will also be an event - I know many French students are planning to attend - that will further strengthen the scientific cooperation between France and Morocco, with students of another, younger generation.

Yes. And I think, as you yourself said, Marrakech is a city where we can do university exchanges with every country in the world far more easily than other places. Speaking of which, Franco-Moroccan cooperation is much easier too because between Marrakech and Paris alone, there are six flights a day. Then there are the other cities. If you count all the flights from here to Europe, there are thirty or forty a week. As part of the Erasmus + programme, we have organised 200 student exchanges with Europe. As you know, the Erasmus scheme is a reciprocal programme. If we send 200 students, we have to welcome 200 students.

That's how it works. And it's good that it exists. If I wanted to come and study in Marrakech, - Don't worry, I'm too old! - would it be quite simple for me, as a French student, to enrol at Marrakech University?

Yes, it's fairly simple. If a student gets in touch with their university to arrange to come and study here, just like a Moroccan student in France, they have to follow the admissions process and contact the coordinators to come here.

You're not that old though! We take everyone.

I'll take up studying again for the pleasure of studying in Marrakech. You'd be very welcome. There's no need for a wild card, we'll enrol you immediately.

We'll see you soon. L'Esprit sorcier will be at COP22, covering all sorts of topics. Thank you so much for joining us, Mr President. And thank you to all your team. Thank you for taking time out on a Sunday morning to talk to us. Good luck to your university and for the upcoming COP22. The whole Science Festival team sends their greetings.

Thank you. We look forward to seeing you.

Likewise. Thank you, goodbye. Just a final brief word... We had to cut short our discussion on Orleans. Let's conclude. Is Orleans and Rabat a cooperation programme too?

Yes. It's a new programme around scientific research on climate change. The idea is to look at water systems and to measure persistent air pollutants. This is a crucial topic for Africa and the world as a whole.

A cooperation programme around climate change issues. Thank you, Moussa Hoummady, for joining us today. See you soon.