K-Pg Asteroid Impact Hypothesis

Paleontology & Fossils 1980 Featured

Discoverers: Luis Alvarez, Walter Alvarez

Overview

Hypothesis that a massive asteroid impact caused the Cretaceous-Paleogene mass extinction 66 million years ago, including the demise of non-avian dinosaurs.

Significance

Introduced catastrophism back into geology and demonstrated that extraterrestrial events can profoundly alter the course of life on Earth.

Methodology

Discovery of a worldwide iridium-enriched clay layer at the K-Pg boundary, an element rare on Earth but common in asteroids.

Impact