They are located in the heart of the province of Liège, on the banks of the Meuse between Huy and Liège, which is the town of Engis.
By Frédéric Marchesani
Extremely rich from a geological point of view, it shelters numerous caves, two of which are located at the level of the village of Ehein, on the edge of the valley of Engihoul, where the stream of the same name runs and which is bordered by the Route des Trente- Six Tournants, well known to the inhabitants of the region.
Discovery and exploration
In the 1830s, the Liège doctor Philippe-Charles Schmerling explored several caves in the vicinity of Engis and Flémalle. He discovered human bones there which, later, were attributed to Neanderthals. In 1860, the British geologist Charles Lyell (1797-1875), president of the Geological Society of London, visited the same cave and made important discoveries there. The site, previously called “Great Engihoul Cave”, will later be renamed “Lyell Cave” in his honor. This is not the only tribute that the scientific world paid to this great man, buried in Westminster among the illustrious: his name also designates a mountain in Canada, Mount Lyell, as well as several craters on the Moon and the planet Mars.
In July 1906, a mine shot, carried out in a quarry belonging to Baron Jacques de Rosée, brought to light a new cave, explored from September 15 by a few specialists including the anthropologist Ernest Doudou. It was named after its owner, who allowed access to scientists and protected access.
Since then, the two caves have been regularly explored by researchers. In the 1970s, the site was acquired by the Carmeuse company, which intended to destroy the rock in order to continue its industrial exploitation. The mobilization of the scientific community led to the classification of the site in 1977. In 1999, convinced of the exceptional interest of these caves, Carmeuse decided to cede full ownership to the Royal Belgian Society for Geological and Archaeological Studies for one franc. symbolic. This is an unprecedented fact in favor of the protection and study of the underworld.
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An extraordinary site, this cave explored for more than a hundred years has always amazed researchers. Ernest Doudou said that it “was a domain much more reserved for fairies than intended to be trampled on by the brutal foot of Man”. Among the main rooms of the place, the most exceptional is undoubtedly the “Crystal Palace”. We are blown away by the cascade of stalactites falling from the ceiling.
This white crystalline harp is the result of a so-called “tubiform” concretion phenomenon, due to the extremely elongated character – up to more than 2 m long – of these stalactites, which have a diameter reduced from 4 to 5 mm d ‘thickness. There are also stalagmites whose main candle is 2.8 m high for a diameter of 60 cm. And that’s not all ! The cave is teeming with other eccentric crystallizations formed by capillarity in the most diverse forms (draperies, hooks, loops, helices, etc.), reminiscent of corals. There is also an important paleontological deposit there, containing fossilized remains of the various fauna that inhabited our regions 300,000 years ago.
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This cave has two entrances. One, to the west, is made up of two corridors, one of which was closed by the factory’s powder store in 1910; the other, to the east, is located at the base of the rock wall of the Engihoul ravine, 13 meters above the Meuse. From west to east, five rooms follow one another in narrow passages. In this second cave, archaeologists worked alongside geologists: human bones attributed to men of the Cro-Magnon type have been unearthed, as well as some flints. However, it is the paleontologists who have had the most work there.
The fossils found have made it possible to illustrate very widely the prehistoric fauna of the end of the Pleistocene, the first geological epoch of the Quaternary (from 2.58 million years to 11,700 years before our era). On the banks of the Meuse, at that very distant time, one could find bears, cave lions, mammoths and other rhinos.
Finally, the major interest of the Lyell cave is in the field of biology. There are three species of troglobia there, a type of cave animal that can only survive in the underground world, very old species that the French naturalist René Jeannel called living fossils. Among these is the only trogloby beetle in Belgium, an extremely rare species and still little studied.
After their classification in 1977, the two caves were included on the list of exceptional heritage of Wallonia. They are indeed of great biological, geological, palaeontological and archaeological interest. Given their fragility, they can never be made accessible to the general public.
A little geology
All along the axis formed by the Sambre and the Meuse, there is an important network of faults, the best known of which is the Eifelian fault, which literally follows the course of these two rivers. In Engis, there is a small fault, the Ivoz fault, on the slope on the right bank. To the south, there is an anticline, a convex fold whose central geological layers are the oldest. It is in the limestones of the Viséen, a geological stage whose rocks were formed between 346 and 300 million years before our era, that the caves of Rosée and Lyell were dug.