At the end of the Cretaceous (65 Ma ago) the Earth suffered the great biological crisis when estimated 60% of the former species, among them the dinosaurs, became extinct. More than 3000 papers were published for the last 30 years, concerning the discussion this question but the decision remains unresolved. Authors propose the new approach to this problem based on the detailed micropalaeontological, lithological, geochemical, nanomineralogical, isotopic and petromagnetic investigations of the unique sedimentary sequence at the Cretaceous-Paleogene boundary in the Gams area, Eastern Alps, Austria.

The conclusions drawn from the results of analysis principally differ from all preexisting data on the transitional layer between the Cretaceous and Paleogene and provide another look at the reasons for the mass extinction of living organisms at 65 Ma ago. These data eliminate the need for opposing volcanism to an impact event: both took place, but the changes in the biota were induced by volcanism, as also was the appearance of the Ir anomaly itself, whereas the fall of a cosmic body occurred approximately 500–800 years later.