Asteroid strikes upset the environment and provide clues via the elements they leave behind. Now, University of Tsukuba researchers have linked elements that are enriched in the Cretaceous–Paleogene (KPg) boundary clays from Stevns Klint, Denmark, to the impact of the asteroid that produced the Chicxulub crater at the Yucatán Peninsula, Mexico. This corresponds to one of the "Big Five" mass extinctions, which occurred at the KPg boundary at the end of the Cretaceous, 66 million years ago. The findings provide a better understanding of which processes lead to enrichment of these types of elements—an understanding that may be applied to other geological boundary events as well.