Approx. 70 million years ago there was a sea where Denmark is today. The sea was warm, and many different animals and microscopic algae lived there. The algae had a shell of chalk. The shells were over the years deposited into a thick layer of chalk at the bottom of the sea.

Over the next many years life in the Cretaceous Sea gradually vanished: the dinosaurs became extinct, the continents rose, and mountains were created and eroded again. The old chalk sea bottom rose above the sea, and the chalk emerged before the last glacial age reached Denmark.

The ice that the last glacial age brought to Denmark scraped enormous crusts off the old chalk sea bottom. The crusts were 50 m thick and were bent, folded and pressed together as in a gigantic concertina crash and formed Høje Møn. For the last 4,000 years the sea has cut into the eastern coast of Møn forming the Cliff we know today.

On average a layer of approx. 20 – 40 cm disappears from the Cliff annually. In about 10,000 years all of Høje Møn will have been eaten away by the sea.