Down to Earth

The Geological Society of Belgium is 150 years old. This milestone will be marked by various events highlighting the full range of professions and fields of investigation encompassed by the term "geology". A science in which ULiège has always excelled.

I

t’s no coincidence that the conference celebrating the 150th anniversary of the founding of the Geological Society of Belgium is being held at ULiège; Liège is its birthplace. The Walloon subsoil, varied, complex, and rich in natural resources, has always attracted scientists. Yet geological science remains one of the lesser-known disciplines, partly because it is not taught as such in secondary education. The image of a scientist wearing hiking boots and collecting rock samples in the countryside is still too often conjured up, even though the geologist's profession and tools have evolved significantly. “Geology, or Earth science, is the discipline aimed at characterising and understanding all the processes governing the origin and evolution of the planet Earth,” explains Bernard Charlier, President of the Geology Department at ULiège, Associate Professor, and FNRS researcher. "Its scope includes both organic aspects, such as the origin and evolution of life, and inorganic ones, related to the structure of the Earth from its core to its surface." This definition applies not only to fundamental science but also to applied science, especially at Liège, where the Faculty of Applied Sciences first trained mining engineers, and later geological engineers.

VISÉEN, TOURNAISIEN…

Although the Society was founded in Liège in 1874, “Liège geology” dates back much further. Annick Anceau, Associate Curator and Secretary of the Geological Society of Belgium, and Associate Professor at the Faculty of Applied Sciences, is well-versed in the history of her discipline*. Even before the creation of the University, one prominent figure stands out: Liégeois d’Omalius d’Halloy (1843–1875), considered the father of Belgian geology. He is notably credited with producing the first geological map of France, Belgium, and the Netherlands (1822). From the very founding of the University of Liège in 1817, courses in geology, palaeontology, and mineralogy were offered. In palaeontology, the name of Philippe-Charles Schmerling (1790–1836), a physician and lecturer in zoology at the University, is renowned for his 1830 discovery in Engis of two fossilised skulls, including that of a child, identified as the first Neanderthal to be unearthed. These skulls are still preserved in the University's collections. More recently, Suzanne Leclercq, the first woman to become a full professor in 1937, established a plant palaeontology laboratory of international repute. Among other accomplishments, she described one of the earliest forests from the Devonian period (between 419 and 359 million years ago) and, more importantly, asserted that fossil plants should be considered true plants rather than merely indicators for dating terrestrial strata. This was a revolutionary idea at the time, in the 1920s.

In terms of geology, we must mention André-Hubert Dumont, who held the chairs of geology and mineralogy from 1835 to 1857. Over several years, he travelled across Belgium to create a detailed geological map of the country. He introduced stratigraphic names derived from Belgian localities, which are still in use today, such as the Famennian, Rupelian, Tournaisian, and Viséan stages. He also took an interest in aquifers. Like his predecessors and successors, Dumont enriched the University’s collections, some of which are still preserved in the Geology Department's archives. Dumont's successor, Gustave Dewalque, another renowned geologist, taught geology for 40 years. He founded the Geological Society of Belgium, headquartered at the University of Liège in 1874, to promote geological sciences and encourage research in the field. It’s worth noting that its members hailed from both academia and industry, with many engineers among them—a diversity that remains relevant today.

“Geology in its broadest sense opens the door to many different careers, especially today,” says Bernard Charlier. “We work on varying scales: from the entire planet to specific regions, and from ancient times to the present day. The diversity of our interests allows us to be involved in the ecological transition like few other professions: water and raw material resources, natural hazard prevention, geothermal energy, and more. The world needs geologists and geological engineers more than ever, and we are short of them. Our students find jobs quickly.”

THE FORMATION OF ROCKS

It’s impossible to explore—however briefly—the opportunities offered by geology without first discussing the formation of their common material: rocks. Jacqueline Vander Auwera, Professor in the Geology Department, is a petrologist and geochemist. Let’s immediately clear up a common misconception: petrology has nothing to do with petroleum! The term comes from "petros", meaning stone. In other words, it is the study of rock formation, in essence the foundation of geological science.

“There are, of course, different origins of rocks,” explains Jacqueline Vander Auwera. “I study magmatic petrology, which involves rocks formed from the solidification of magma, either at a certain depth within the Earth (these are called plutonic rocks, like granites) or at the surface, where volcanic rocks, such as lava flows, form.” These are two fairly common types of rock, but she specifically studies the volcanic rocks of Chile, located in the Andean Arc. Magmatic rocks are of potential economic importance, as they may host mineral deposits such as platinum (in South Africa, for example) or copper (as in Chile). “But the real interest in studying these rocks is to better understand the conditions under which magma solidifies, begins to crystallise at depth, and rises to the surface. Ultimately, it helps us better understand the nature of the Earth's mantle. The formation of these magmatic rocks is linked to the Earth's internal dynamics and plate tectonics. They inform us about how this system operates.”

In order to best characterise these different parameters, Jacqueline Vander Auwera and her team travel across the volcanoes of Chile, collecting lava samples, identifying the minerals they contain, and analysing the balance between them to learn about the conditions under which the lava formed (pressure, temperature at which it crystallised, the water content of the magma, etc.). “Some data, like the locations of magma reservoirs, are essential for predicting volcanic eruptions. They contribute to a better understanding of volcanoes, although predicting eruptions remains very complicated. It is always important to know the history of each volcano

LIKE READING A BOOK

Everyone has a favourite era: some prefer the Sixties, others the Eighties… Anne-Christine Da Silva, a lecturer in the Geology Department, is passionate about the Devonian period. It’s easy to see why this geological era, which lasted about 60 million years (between 419 and 359 million years ago), is so intriguing: a warm climate, high sea levels, abundant and diverse fauna, the rapid spread of plants on land… and, to end the period, an extinction that wiped out nearly 70% of species. Any resemblance to our current time is purely coincidental.

“The Devonian period can be observed all over the world, including in Wallonia, which at the time was covered by oceans and located much further south than it is today. There are numerous high-quality outcrops here,” the researcher explains. “This makes it relatively easy to study the successive climates of that time.” Thus, the alternating bands of shale (clay) and limestone reveal cycles in seasonal intensity, related to the Earth’s orbit around the Sun and its rotation. “We try to identify these cycles in the rocks, which helps us understand the climate. Since these cycles have a constant duration, they serve as precise chronometers, allowing us to date the rocks.”

Dating rocks as accurately as possible is a challenge faced by all geologists, and it’s one of Anne-Christine Da Silva’s tasks. To do so, she travels to various countries (the United States, China, Australia, the Czech Republic), and recently to Morocco, to study a large Devonian outcrop that spans 14 million years, which helps refine the time constraints for different layers. This outcrop holds another important feature: “It’s a section where extinction events are associated with observable anoxic conditions, allowing us to better understand them.” Oceanic anoxia refers to periods when the oxygen content of the oceans dropped, leading to extinctions. These anoxic events are another area of research for the Liège-based scientist. “They are clearly identifiable worldwide, from the United States to Morocco and even here in Belgium, for example in Sprimont. During periods of anoxia or extinction, many animals die without being eaten or decomposed by their counterparts, leading to an accumulation of organic matter—carbon—on the ocean floor, and the shales turn black. Sometimes, it’s almost like coal!” Once again, any resemblance to the current period is purely coincidental.

EXTINCTIONS

Professor and director of the Evolution and Diversity Dynamics Lab (Eddy Lab), Professor Valentin Fischer readily admits: “Here, we’re almost doing biology.” His team of palaeontologists includes as many biologists as geologists. “Palaeontology is the study of ancient life forms; a definition that allows for a wide diversity of studies.” As we have seen, ULiège has always been at the forefront of this field, helped by the richness of the Walloon subsoil. However, for a long time, palaeontology was primarily focused on taxonomy: the description and classification of new species within the tree of life. “Nowadays,” explains Valentin Fischer, “we do a lot of quantitative palaeontology. We create highly detailed 3D models of fossils. From these, we try to better characterise extinct species, understand their capabilities, and examine the mechanisms that led to their extinction. But to properly interpret the past, we also need a thorough knowledge of geological processes, the rocks in which the fossils are embedded, and stratigraphy, or the geological time scale.” Indeed, the study of past extinctions is a major research theme at the EDDy Lab. This includes redefining the events marking the boundary between the Devonian and Carboniferous periods (which immediately follows the Devonian). By studying dozens of sites and thousands of fossils, Liège researchers have proposed a new boundary based on events present in Walloon rocks, including a sharp drop in sea levels, extinction, and the disappearance of ecosystems like coastal marshes. This boundary has been recognised and is now awaiting the designation of a Walloon locality to name it after!

Researchers at the laboratory have also studied the evolution of “sabre teeth”, those elongated upper canines seen in certain felids. These animals were modelled, allowing, for example, a simulation of their biting mechanism and an analysis of how bite stress was distributed through their bones. However, marine predators also command attention. Among them are mosasaurs, large marine reptiles from the age of the dinosaurs, which get their name from the fact that the first fossil of this type was found near Maastricht in a chalk layer (although the River Meuse didn’t exist at the time, of course!). Reaching lengths of up to 12 metres, they were the largest marine predators at the end of the Cretaceous period. “They are of interest to us,” explains Valentin Fischer, “because they represent one of the last major groups of marine reptiles, which became extinct during the mass extinction event that also wiped out the dinosaurs. What fascinates us is this: what environmental phenomena could affect these apex predators at the top of the food chain? We’ve been able to demonstrate, for several groups of fossil marine reptiles, that if changes are abrupt, extinction rates rise sharply.” Again, any resemblance to the current situation….

HYDROGEOLOGY AND GEOTHERMAL ENERGY

Geology isn’t just a science; it’s also an applied science. Philippe Orban, a research fellow in the “Urban and Environmental Engineering” unit of the Faculty of Applied Sciences, asserts: “There are two main areas in the geological engineering profession: ‘mineral resources and recycling’, and ‘engineering and environmental geology’. Both areas require an in-depth knowledge of the subsoil.” Philippe Orban is a geological engineer specialising in hydrogeology; he studies groundwater resources and how to manage and protect them. At ULiège, efforts are underway to understand how groundwater (aquifers) will evolve under the impact of climate change. There’s also work on how to recharge aquifers in a controlled way to counter precipitation deficits. “Our job is also to protect groundwater resources. In short, we provide decision-making tools through the numerical models we develop. Everything we do involves both experimental work and mathematical modelling.”

The same is true for geothermal energy, a field in which Philippe Orban has now specialised. “The subsoil has an extraordinary quality: its temperature remains almost constant. So, in winter, it can be used for heating, and in summer for cooling. Shallow geothermal energy is therefore an asset for decarbonising building heating. However, this requires a thorough understanding of geology and how the underground environment works in order to use it wisely and sustainably.” The engineer thus uses geological maps, boreholes, and geophysical surveys that allow the investigation of the subsoil without having to drill everywhere. “Understanding the nature and structure of the subsoil is essential, particularly here in Wallonia, where the subsoil is complex.”

ULiège is also studying mine geothermal projects, which involve recovering heat stored in the water that has filled the cavities left by mining. “We’re developing numerical modelling tools to understand how the subsoil behaves: if we inject heat at one location, how does it behave? How does this heat dissipate in the ground, particularly due to water movement?” But one thing is clear to the geological engineer: even though geothermal energy is a valuable source of energy, it will be most effective in buildings that are well insulated.

*Annick Anceau et al., “Les sciences géologiques à l’Université de Liège : deux siècles d’évolution,” in Bulletin de la Société Royale des Sciences de Liège, vol. 86, 2017.