About the World Heritage
Nestled within the spectacular landscapes of the Limfjord lies a place where an extraordinary story is preserved in cliffs, geological layers and fossils. The area around Fur and Mors contains some of the world's best-preserved evidence of life from 55 million years ago.
Nestled within the spectacular landscapes of the Limfjord lies a place where an extraordinary story is preserved in cliffs, geological layers and fossils. The area around Fur and Mors contains some of the world's best-preserved evidence of life from 55 million years ago. This exceptional geological record is the reason why the area has been inscribed on the UNESCO World Heritage List.
The unique moler (diatomite) cliffs reveal the story of volcanic eruptions, dramatic climate change and ancient ecosystems, making the area one of Denmark's most remarkable destinations for nature and geology.
Whether you're enjoying a holiday by the Limfjord, exploring with your family or living nearby, unforgettable experiences await. Wander along the towering cliffs, discover fossils that are millions of years old, admire the dramatic landscapes and learn why this unique corner of Denmark has captured worldwide attention.
Here you can explore the story behind the World Heritage site and find inspiration for your next visit.
Why is the area unique?
Hanklit and Knudeklint are exceptional geological sites renowned for their extraordinary wealth of exceptionally well-preserved fossils. More than 700 species of prehistoric organisms—including fish, birds, insects and plants—have been discovered in the moler deposits.
Many of these species lived shortly after Earth's fifth and most recent mass extinction, the event that wiped out the dinosaurs. Hanklit and Knudeklint therefore provide a unique window into one of the most significant turning points in the history of life.
These cliffs preserve an extraordinary natural archive that offers unique insights into how life recovered after the fifth mass extinction. They reveal crucial evidence of an important stage in evolution, documenting the ancestors of many of today's plants and animals, particularly fish.
The Western Limfjord also contains exceptionally well-preserved fossils embedded in geological layers formed during the most intense period of global warming since the extinction of the dinosaurs.
Scientists refer to this dramatic warming event as the Palaeocene–Eocene Thermal Maximum (PETM). This period is of global scientific importance because it provides valuable insight into how rapid climate change affects organisms and entire ecosystems.
The PETM is widely regarded as one of the best natural analogues for understanding both present-day and future climate change on Earth.
The UNESCO World Heritage Nomination
In 2016, a unanimous team of researchers concluded that the exceptionally well-preserved fish fossils found in the diatomite deposits on Fur and Mors provided the strongest basis for a UNESCO World Heritage nomination.
Being inscribed on the UNESCO World Heritage List is an extraordinary achievement, reserved for only a select few places worldwide. A site can only be designated as UNESCO World Heritage if it possesses Outstanding Universal Value – meaning it has exceptional significance not only for present generations, but also for future generations across the globe, transcending national borders.
One of the features that makes the Western Limfjord, including Hanklit and Knudeklint, truly unique is the remarkable state of preservation of its fossils. Many are preserved in extraordinary detail, with some retaining their original three-dimensional form. This exceptional preservation is due to the presence of limestone concretions, locally known as cementstones.
Acting almost like a coffin or sarcophagus, these concretions protected the fossils from being compressed over millions of years.
Limestone concretions – or cementstones – occur as isolated nodules, sometimes exceeding one metre in diameter, or as continuous layers. They formed when calcium-rich fluids filled pores and cavities within the diatomite sediment beneath the ancient seabed, where they gradually hardened. As a result, these concretions preserved plants and animals with a level of detail unmatched anywhere else in the world.
The extraordinary preservation has even allowed scientists to identify original biological molecules within some fossils. For example, molecular traces of haemoglobin from red blood cells have been discovered in the carbon-rich film representing the original skin of a sea turtle. Together, these discoveries provide an exceptionally detailed insight into the rich marine ecosystem that existed approximately 55 million years ago.
These fossils are recognised as among the best-preserved anywhere in the world and represent the oldest diverse fish fauna known after the mass extinction event that wiped out the dinosaurs and many other species.
The diatomite cliffs on Fur – especially Knudeklint – are also the only place in the world where it is possible to observe directly how global climate change 56 million years ago affected marine fish populations.
In 2024, the UNESCO World Heritage nomination was formally submitted to Denmark's Minister for Culture, Jakob Engel-Schmidt. The nomination consisted of a 274-page main dossier accompanied by a 257-page volume of supporting documentation and appendices. It was presented by a delegation of ten representatives from the municipalities of Skive and Mors.
In late July 2026, the Western Limfjord, represented by Hanklit and Knudeklint, was inscribed on the UNESCO World Heritage List under Criterion (viii), recognising the area's "outstanding examples representing major stages of Earth's history and the evolution of life."
Fossils and History
The coastal cliffs at Hanklit and Knudeklint contain an extraordinary wealth of exceptionally well-preserved fossils representing a wide variety of prehistoric plants and animals. Fossils found here include:
- Marine vertebrates (fish, sea turtles, etc.)
- Terrestrial vertebrates and invertebrates (birds, insects, etc.)
- Marine algae
- Terrestrial plants (petrified tree trunks, branches, leaves, spores and pollen, etc.)
- Marine invertebrates (crabs, starfish, etc.)
The Western Limfjord has been renowned for its fossils for centuries. Exactly how long is difficult to determine, but at least since 1763, when the first simple drawing of a fossil fish from Fur was made.
Another hundred years passed before the first scientific descriptions of fossils from the area were published. The first insects preserved in the diatomite deposits were scientifically described in 1922, while the first fossil fish was not described until 1941—almost 200 years after that first illustration.
Since then, the Eocene deposits and fossils of the Western Limfjord have become increasingly important to international scientific research on a wide range of fossil groups, particularly fish, birds and insects.
Today, the international scientific importance of Hanklit and Knudeklint continues to grow. This is due to both the remarkable abundance of fossils and their exceptional state of preservation. Equally significant is the fact that these cliffs expose deposits formed during the earliest period following the extinction of the dinosaurs—when the development of the ecosystems and life forms we know today began.
Fossils of particular national importance are protected under Danish law for scientific research and museum collections. Exceptional fossils classified as Danekræ ("National Treasure Fossils") are the property of the Danish State. Anyone who discovers or comes into possession of such fossils after 1989 is legally required to hand them over immediately to the Natural History Museum of Denmark or a nationally recognised local natural history museum, typically Museum Mors or Museum Salling.
Researchers, amateur geologists and visitors are welcome to collect fossils in several former diatomite quarries on the islands of Fur and Mors. These sites are not subject to the same level of protection as the coastal cliffs and the nominated UNESCO World Heritage localities.
Outstanding fossil discoveries from the diatomite deposits are preserved in the collections of Museum Mors, Museum Salling and the Natural History Museum of Denmark in Copenhagen.
Good to know about the Western Limfjord (Hanklit and Knudeklint)
- The coastal cliffs contain around 200 dark volcanic ash layers from ancient eruptions. These layers provide precise dating of both the sediment deposits and the fossils. The diatomite (moler) between the ash layers is light in colour.
- Scientists believe that diatoms first appeared during the Jurassic Period at least 175 million years ago. Their shells are made of silica, a material similar to glass. They are therefore sometimes described as "algae living in glass houses." Diatoms are still widespread in oceans and lakes today.
- Most diatoms are microscopic, measuring less than the width of a human hair.
- Diatomite (moler) consists of 45–65% fossilised diatoms. The remainder is made up of clay minerals and small amounts of volcanic ash.
- Researchers can distinguish the different ash layers with great precision and, in some cases, even identify the volcanic eruptions that produced them. Ash Layer -17 is believed to originate from the Gardiner Volcano in East Greenland, while Ash Layer -33 is thought to come from the island of Lundy, off the coast of Cornwall, England.
- This locality has produced more fossil butterflies than anywhere else on Earth, including the world's oldest known butterfly, dating back 55 million years.
- A fossil grasshopper was preserved so exceptionally well that scientists were able to reconstruct the song it made 55 million years ago.
- Some fossils are preserved in extraordinary detail, with eggs still visible inside insects and even the tiny facets of crane fly eyes remaining intact.
- During the dramatic climate change at the Palaeocene–Eocene boundary, around 56 million years ago, sea temperatures around present-day Mors and Fur increased by 7–10°C. This warm period lasted for approximately 170,000 years.
- Tasbacka danica, affectionately known as "Luffe", is the best-preserved fossil baby sea turtle ever discovered.
- Denmark's three largest fossils are petrified trees, all found on Mors. They measure up to 9.5 metres in length and 80 centimetres in diameter.
- The last two glacial advances of the most recent Ice Age, between 30,000 and 20,000 years ago, shaped the landscapes we see today. The glaciers extended as far south as Bovbjerg, near Lemvig, before coming to a halt.
- The ice retreated around 20,000 years ago. This is why rocks such as Norwegian rhomb porphyry, transported by the glaciers from the Oslo region, can be found here today. The rock itself originated from lava approximately 300 million years ago.
- Fossils can be found on almost any beach with coastal cliffs, as well as in gravel pits, limestone quarries, clay pits and diatomite (moler) quarries—some of which are still active. Always obtain the landowner's permission before entering. Safety equipment such as helmets, safety glasses, sturdy footwear and high-visibility clothing may be required. Access is generally at your own risk.
Good to know about moler (pronounced: MOH-ler)
- Moler is a unique Danish sedimentary rock with many practical uses. It is used, for example, to produce heat-resistant insulating bricks for fireplaces and chimneys, as well as filtration media for brewing beer.
- The high content of fossilised diatoms makes moler lightweight, porous and an excellent natural insulator.
- Its exceptional absorbency means it is widely used in cat litter and for absorbing liquids such as oil.
- Moler is also used in the production of plastics and has historically been an important ingredient in the manufacture of dynamite.
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