Fiskeler The Cretaceous-Tertiary boundary clay Implementation of the World Heritage Convention (2008). There are more than 500 Cretaceous-Tertiary boundary sites worldwide, only 17 meet the three prerequisites of completeness of the succession across the boundary, scientific documentation, and the presence of a boundary layer that is enriched in iridium and other elements, considered to be mainly or partly of impact origin. The 17 sites have been analyzed with a focus on three major issues, Stevns Klint site ranks first in total (see above). Stevns Klint (klint = cliff) illustrates the most spectacular global mass extinction event in the history of Earth: The Cretaceous-Tertiary boundary. The mass extinction that occured about 65 million years ago is particularly spectacular due to its association with an asteroid impact and because it marks the extinction of more than half of all species on Earth, including land-living dinosaurs and large marine reptiles. Stevns Klint forms the best exposed Cretaceous-Tertiary boundary section in the world. In 2014 UNESCO included Stevns Klint in Denmark in the World Heritage List (#1007). to front page…http://meteorites.dk