Fish dish at Stevns Klint

Stevns Klint at Højerup is internationally renowned as the best place in the world to see the consequences of the great meteor impact 66 million years ago, which wiped out half of all animal life, including the dinosaurs. At the bottom, the cliff is formed of writing chalk, deposited in a warm sea during what we call the Cretaceous period, over millions of years. Writing chalk is soft and is washed away relatively easily by the water. At the top, the cliff consists of limestone, formed approximately 60-66 million years ago in the geological period we call the Tertiary. It is considerably harder, the sea has difficulty eroding it, and for centuries it has been used as building stone. Absalon used it when he founded Copenhagen in 1167, Brønshøj Church was built from it around 1180, all the medieval churches, Gjorslev Castle, and many secular houses on Stevns are built from it. In many places, the limestone layer juts out several metres beyond the writing chalk in the cliff, due to sea erosion.

On the boundary between these two layers, called the K/T boundary, lies the K-T clay. It is found in a band, varying between 30 cm at its thickest and virtually nothing at its thinnest. The K-T clay is a grey-brown clay layer, composed of dust from the meteor impact 66 million years ago at what is now the Yucatán Peninsula in Mexico. The seabed at that time was not completely horizontal, but had small depressions, basins, in which the dust settled. This is why the thickness varies today.

UNESCO World Heritage and the fishing trade

It was at Højerup that two American researchers, Luis and Walter Alvarez (father and son, respectively an astrophysicist and a geologist), took samples of the fish clay for analysis of its iridium content. Iridium is a very rare element found in the Earth's interior as well as in outer space. Dust from outer space containing iridium constantly falls to Earth at a fairly constant rate, and the researchers wanted to try to determine the length of the period between the end of the Cretaceous period and the beginning of the Tertiary period by measuring the amount of iridium. They had previously taken a sample in Gubbio, Italy, but doubted the measurement, as the iridium content there was far too high. They found the excessively high content again in the sample from Stevns, and they now arrived at the theory that the transition between the Cretaceous and Tertiary periods had been short and violent and was caused by a very large asteroid impact. When the theory was finally confirmed by the discovery of the remnants of the crater at Yucatán, the way was paved for Stevns Klint's designation as a World Heritage Site as the place on Earth where the very abrupt transition can be best and most easily witnessed.

The specific find site is located a little south of the stairway descent, but due to cliff falls and the risk of further cliff falls, it may no longer be safely accessible.

The stone with the UNESCO plaque, testifying to the World Heritage designation, is placed at the top of the stairs.