The Chicxulub impact
A ten-kilometre asteroid hits the Yucatan at 20 kilometres per second, and the Mesozoic ends that day.
- When
- Known to
- ± 43 thousand years
- Era
- Cretaceous, Mesozoic
An asteroid roughly ten kilometres across strikes shallow sea over the Yucatan Peninsula, excavating a crater about 180 kilometres wide and dated to 66.043 million years ago with an uncertainty of only 43,000 years. The target rock is unusually rich in sulfate and carbonate, so the impact injects enormous quantities of sulfate aerosol and dust into the stratosphere. Ejecta rains back through the atmosphere worldwide, heating the sky to broiling temperatures; tsunamis cross the Gulf; and the resulting layer of iridium-rich clay is found at the boundary on every continent.