At Stevns Klint a thin dark band of clay sits at eye level in a white chalk cliff, marking the exact moment 66 million years ago when an asteroid strike ended the age of dinosaurs. It was evidence from this layer that helped prove the impact theory of mass extinction.
At a glance
Stevns Klint is a chalk cliff on the eastern coast of Zealand, Denmark, running along the Baltic shoreline. Its face exposes pale Cretaceous chalk below and above a narrow dark band known as the fish clay, which marks the Cretaceous-Paleogene boundary, the point in the geological record where an asteroid impact is thought to have triggered a mass extinction. The site is inscribed as a UNESCO World Heritage Site, listed in 2014.
Key facts
- Boundary layer: the fish clay is one to three centimetres thick, dark grey to black, and rich in pyrite and fish remains.
- Scientific role: the layer’s iridium concentration, far above normal background levels, was central evidence in the 1980 Alvarez hypothesis linking the extinction to an asteroid impact.
- Confirmation: the hypothesis was corroborated when the Chicxulub impact crater, on Mexico’s Yucatán Peninsula, was identified in 1991.
- Cliff form: the exposed cliff face stands roughly 20 to 40 metres high and runs for about 17 kilometres along the coast.
- Coordinates: approximately 55.2700° N, 12.4400° E.
History
The chalk of Stevns has been quarried since the medieval period, supplying stone for churches across Zealand, including some of Copenhagen’s oldest buildings. The small medieval church at Højerup, built around 1329, stood at the cliff edge as erosion advanced beneath it; in 1928 its choir collapsed into the sea when the underlying chalk gave way. The nave and tower survived and the choir was later rebuilt, and the church remains in use.
During the Cold War the Danish military built Stevnsfort into the chalk of the cliff, an underground installation constructed in the early 1950s and used until 1990 to help coordinate naval defence of the Øresund strait. It now operates as a museum.
What you see
A visitor centre near Højerup, opened in 2014, introduces the geology and human history of the cliff, including an exhibit on the Cretaceous-Paleogene boundary. A path runs along the clifftop for several kilometres between the centre and Højerup, giving views over the Baltic Sea.
The main draw for many visitors is the base of the cliff, where the fish clay is visible at the contact between the two white chalk layers and can be reached and touched at low tide. The reconstructed church at Højerup, perched at the cliff edge with its Baltic outlook, is the other principal stop.
Practical information
- Season: the visitor centre and Stevnsfort museum operate seasonally, roughly from spring to autumn; check the official Geo Center channel for current dates.
- Cliff walk: the clifftop path is accessible year-round even when the buildings are closed.
- Reaching the boundary layer: walking shoes are sufficient and low tide gives the best access to the cliff base.
- Tickets: admission details for the Geo Center and Stevnsfort are best confirmed directly with the visitor centre before travelling.
Getting there
Stevns Klint lies south of Copenhagen. It can be reached by S-tog train from Copenhagen Central Station to Køge, followed by a local bus toward Stevns, or by car via motorway E20 and onward on Route 209 and Route 261 to Højerup, where the visitor centre stands.
Nearby
- Køge — a well-preserved medieval town with half-timbered houses around its main square, the church of St Nicholas, and a museum covering local history including the 1677 Battle of Køge Bay.
- Møns Klint — another chalk cliff further along the coast, higher than Stevns Klint at its peak, with its own geological visitor centre, sea-cave access by kayak, and the Liselund landscape garden above the cliff.
Sources
- Wikipedia, Stevns Klint
- Wikipedia, Cretaceous-Paleogene extinction event
- Wikipedia, Alvarez hypothesis
- UNESCO, Stevns Klint
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