Discover Belgium and Explore the Geodiversity of the Famenne-Ardenne UNESCO Global Geopark
- Wayne Munday
- Aug 27
- 5 min read
Updated: Sep 10
Sip back and discover Belgium and explore the Famenne-Ardenne UNESCO Global Geopark in Wallonia, southern Belgium. Designated in 2018, the Geopark spans rolling hills, river valleys and distinctive karst landscapes and is divided into three key geological zones: the northern Famenne Depression of shales, the southern Ardennes Plateau of resistant sandstone and the central Calestienne limestone corridor, famed for caves, cliffs and underground rivers. These landscapes preserve a rich Paleozoic rock record including Devonian and Carboniferous sandstones and limestones folded during the Hercynian orogeny and reveal fossil-rich strata that document ancient warm shallow-marine ecosystems. The fossil record includes trilobites, brachiopods, coral, and stromatolites that capture the dynamics of a Middle Devonian benthic community as well as global events such as the short-lived Choteč Event - a pulse of oceanic anoxia that reshaped marine biodiversity. Today, the Geopark’s geology underpins vibrant ecosystems: limestone soils support rare orchids, ferns, and calciphile grasses while Ardennes forests shelter deer, wild boar, and birds of prey The rivers such as the Lesse and Ourthe carve gorges inhabited by Otters, Kingfishers and Bats. The Famenne-Ardenne offers the visitor immersive experiences from exploring the Han-sur-Lesse caves, hiking or kayaking through limestone valleys to discovering fossil-rich outcrops and observing diverse wildlife.
The landscape of Famenne-Ardenne is defined by three key geological units. Firstly, the Famenne Depression formed from Paleozoic marine sediments of the Devonian and Carboniferous periods. These deposits were uplifted and folded during the Hercynian orogeny around 295 million years ago before being flattened in Mesozoic and Cenozoic times. Subsequent erosion or peneplanation levelled the terrain with the softer shales eroding into a lowland while harder sandstones and limestones resisted to form surrounding ridges. The depression is flanked by the sandstone uplands of the Ardennes Plateau and the karstic limestone belt of the Calestienne making it a distinctive geological feature and explains why the Famenne sits lower than its surrounding uplands.
The Ardennes Plateau in southern Belgium is a remarkable geological landscape shaped by over 500 million years of Earth’s history. Its foundations were laid during the Paleozoic Era, when shallow seas deposited vast layers of sandstone and limestone that were later folded and uplifted into mountains during the Hercynian orogeny, around 300 million years ago, as part of the formation of Pangea. Over time, these mountains were eroded into a broad plain, but more recent tectonic uplift possibly linked to mantle plume activity allowing the rivers of the Ourthe and Lesse to carve deep gorges into the rising plateau.
The Calestienne is a narrow limestone belt within the Famenne-Ardenne UNESCO Global Geopark in southern Belgium forming a striking geological boundary between the shale lowlands of the Famenne Depression to the north and the sandstone uplands of the Ardennes Plateau to the south. Composed mainly of Middle and Upper Devonian limestone dated to between 393 – 383 million years old the Calestienne originated in a shallow marine reef environment before being folded during the Hercynian orogeny and later reshaped by erosion. Its soluble limestone bedrock has produced extensive karst landscapes, including sinkholes, disappearing and re-emerging rivers such as the caves of Han-sur-Lesse. Today, the Calestienne stands out as a distinctive east–west strip across Belgium.
The fossil record of the Famenne-Ardenne UNESCO Global Geopark is linked with the Dinant Synclinorium a once marine basin that experienced major geological folding during Variscan mountain building event now spanning southern Belgium and northern France. The Calestienne region of the Ardennes in southern Belgium is within the Dinant Synclinorium and renowned for its fossil-rich Givetian Stage limestones dated to between 387.7 - 382.7 million years ago during the Upper Devonian.
Well-preserved fossil trilobites from the Eifelian strata between Nismes (Belgium) and Vireux-Molhain (France) are recorded in the Lower Eifelian Vieux Moulin Member of the Jemelle Formation where diversified trilobite assemblages are found in the dark shales and siltstones and replace the less diverse fauna of the underlying Eau Noire Formation, possibly reflecting the Choteč Event. The Ardenne has exceptionally well-preserved fossilised trilobites from families including Phacopidae, Lichidae, Proetidae, Homalonotidae, Acastidae and Odontopleuridae.
There is an indication of a local influx of trilobites termed the "Vieux Moulin Event" peaking in diversity during the middle Eifelian Chavées Member before declining in the upper formation. Several trilobite taxa are described including Asteropyge boeckae, Cyphaspis insolata, Diademaproetus pertinax, Gerastos kesselaeri and Tropidocoryphe insciens. Additional new species have been found and include Astycoryphe rugocauda from the lower Eifelian Couvin Formation and Gerastos silvicultrix from the uppermost Emsian Heisdorf Formation highlighting the region’s exceptional trilobite diversity and paleontological significance.
Alongside the trilobites are also brachiopods that are equally significant in their diversity and turnover reflecting environmental fluctuations as well as invertebrates such as stromatoporoids, tabulate corals, hydroids and ostracods.
These assemblages are typically associated with shales and siltstones, deposited in low- to moderate-energy conditions that ranged from lagoonal settings to open shallow-marine siliciclastic facies. The fauna not only documents local ecological diversity but also records the impact of broader paleoenvironmental events including global sea-level changes and possibly the Choteč Event which influenced marine biodiversity across the Devonian.
The Choteč Event, also known as the Jugleri Event, was a short-lived global episode of oceanic anoxia that occurred at the transition from the Emsian to Eifelian stages of the Devonian Period around 392.5 – 393.1 million years ago. It is recognised in the geological record by the deposition of dark, organic-rich limestones and shales reflecting oxygen-depleted marine conditions. During this interval, marine ecosystems shifted dramatically: plankton and nekton (free-swimming organisms) proliferated fueled by sudden algal bloom particularly prasinophycean algae while benthic communities declined due to oxygen stress on the seafloor. This event was triggered by enhanced continental weathering and increased runoff of nitrogen and phosphorus which delivered nutrients to the oceans and caused a widespread reduction in water clarity, depletion of oxygen and stress to aquatic biodiversity.
The region’s diverse geology directly sustains its ecosystems: limestone soils of the Calestienne support rare orchids, ferns, and calciphile grasses, while the Ardennes forests shelter deer, wild boar, and raptors. Rivers such as the Lesse and Ourthe carve dramatic gorges that provide habitats for Otters, Kingfishers and Bats. Protected under the Natura 2000 network these fragile habitats highlight the intimate relationship between geology and ecology, with karst topography shaping soils, hydrology, and vegetation to create microhabitats for endemic species.
The Famenne-Ardenne UNESCO Global Geopark is a remarkable destination where geological history, biodiversity, and human culture converge to create a living landscape of scientific and aesthetic wonder. Spanning rolling hills, river valleys, and distinctive karst terrains, the Geopark is defined by three key geological zones: the shale lowlands of the Famenne Depression, the resistant sandstone of the Ardennes Plateau, and the limestone corridor of the Calestienne, renowned for caves, cliffs, and underground rivers. These landscapes preserve a rich Paleozoic rock record, including Devonian and Carboniferous sediments folded during the Hercynian orogeny, and host fossil-rich formations that capture ancient shallow-marine ecosystems, from trilobites and brachiopods to stromatolites and corals, and even record global events such as the Choteč Event, a short-lived pulse of oceanic anoxia. Today, this geology underpins thriving ecosystems: limestone soils support rare orchids, ferns, and calciphile grasses, Ardennes forests shelter deer, wild boar, and birds of prey, while rivers such as the Lesse and Ourthe carve gorges inhabited by Otters, Kingfishers and Bats. Protected under the Natura 2000 network, these habitats showcase the intimate link between rocks, water and life.