The geotope profile consists of geological succession deposits from several hundred millions of years. It has nearly vertical layers with continual exposure from the Permian period to the Cenozoic era. The fossils and geology was recorded during the 1910s and 1920s, and is used within geological sciences as a strategic reference profile. Fossilized footprints of an Iguanodon dinosaur, 0.5 metres (1 ft 8 in) in diameter, dating from 100 million years ago, have been found at Festningen. They were 10 to 12 metres (33 to 39 ft) long and 3 to 5 metres (9.8 to 16.4 ft) tall. Located on a cliff, they were highly exposed to erosion; after they were found and copied, the slab fell into the sea.