Everything Everywhere Daily: History, Science, Geography, & More The Chicxulub Impact: The Asteroid That Killed the Dinosaurs
Mar 19, 2026
A deep dive into the asteroid strike beneath the Yucatan and how researchers located a hidden crater. Exploration of the K‑Pg boundary, iridium spikes, shocked minerals, and global ejecta that changed scientific thinking. A look at the immediate cataclysms, atmospheric aftermath, and how mass extinction reshaped which animals thrived afterward.
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Scale And Energy Of The Chicxulub Impact
- The Chicxulub impact excavated a ~180 km crater from a ~12 km asteroid striking at ~20 km/s.
- The event released energy equal to billions of nuclear bombs and left no obvious surface hole after 66 million years of geology.
Thin Clay Layer Signals Sudden Global Turnover
- The abrupt global faunal turnover at the K-Pg boundary was visible as a thin clay layer worldwide separating rich Cretaceous fossils from Paleogene assemblages.
- That thinness implied a rapid event, challenging 19th-century gradualism dominant in geology.
Iridium Layer Tied Extinction To An Extraterrestrial Source
- Lewis and Walter Alvarez found unusually high iridium in the boundary clay, a metal rare in Earth's crust but common in meteorites.
- The same iridium-rich layer was found globally, pointing to a single massive extraterrestrial fallout event.