A mountain range born in minutes
Some 66 million years ago, an asteroid around 10 kilometers in diameter struck the shallow sea where the Yucatán Peninsula now sits. The impact released energy equivalent to 100 trillion tons of TNT, vaporizing thousands of cubic kilometers of rock instantly. This cataclysmic event, which triggered the mass extinction that ended the age of dinosaurs, created one of the largest impact structures on Earth: the Chicxulub crater. Buried today under thick layers of sediment, the crater is approximately 200 kilometers (120 miles) wide.
Unlike smaller, bowl-shaped craters, Chicxulub has a fascinating and unusual feature at its center: a "peak ring." This circular inner mountain range shows an impact of immense scale. The process began with the formation of a transient cavity about 30 kilometers deep and 100 kilometers wide. Almost immediately, the center of this cavity rebounded, shooting up into a towering, unstable peak higher than the Himalayas. This central uplift then collapsed outward, forming the circular range of mountains known as the peak ring. The entire mountain-building process took less than 10 minutes.
Evidence from the deep
For decades, the precise mechanics of peak ring formation were debated by scientists. The breakthrough came in 2016 with the International Ocean Discovery Program (IODP) Expedition 364. A team drilled over 1,300 meters below the seafloor into the crater's peak ring. The recovered core samples provided direct evidence for the dynamic collapse model.
The drill core contained fractured, shocked granite, a type of rock that normally forms deep within the Earth's crust. This showed that the peak ring is made of deep crustal rock that was violently uplifted. Analysis showed this granite had traveled from a depth of 8 to 10 kilometers to the surface and then collapsed outward in a matter of minutes. The rocks were also found to be unusually porous and less dense than typical granite, shattered by the immense forces of the impact. This unique geology gives Chicxulub its status as the only impact structure on Earth with a well-preserved and accessible peak ring for scientific research.
The crater's existence was first proposed in the late 1970s. Geophysicists Antonio Camargo and Glen Penfield, working for the state oil company Pemex, identified a massive, circular gravity anomaly under the peninsula but couldn't initially prove its impact origin. Their discovery was later connected to the global layer of iridium-rich clay at the Cretaceous-Paleogene (K-Pg) boundary, confirming the site of the dinosaur-ending impact.