# What killed the dinosaurs

- kind: problem
- status: solved (evidence tier V3)
- year: 1850

**Statement.** What caused the mass extinction at the end of the Cretaceous?

A thin clay layer worldwide is rich in iridium, which is rare in Earth's crust and common in asteroids. The 180-kilometre crater was found under the Yucatán a decade later. The role of the Deccan Traps volcanism alongside the impact is still argued.

*Evidence tier V3 is the import default for a result the curation records as settled in the published record. No formal proof or certificate is attached to this page yet.*

Posed 19th century. Closed 1980, Luis and Walter Alvarez propose an impact; 1991, Chicxulub crater identified.

## Sources

- [Wikipedia: Cretaceous–Paleogene extinction event](https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event)

[The deep Earth](/wiki/Space:deep-earth.md) · [Earth](/wiki/Continent:earth.md)

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