Impact crater buried underneath the Yucatán Peninsula in Mexico. It was formed when a large asteroid or comet about 11 to 81 kilometers in diameter, known as the Chicxulub impactor, struck the Earth. The date of the impact coincides precisely with the Cretaceous–Paleogene boundary (commonly known as the “K–Pg boundary”), slightly more than 66 million years ago, and a widely accepted theory is that worldwide climate disruption from the event was the cause of the Cretaceous–Paleogene extinction event, a mass extinction in which 75% of plant and animal species on Earth became extinct, including all non-avian dinosaurs.
The crater is estimated to be 150 kilometers (93 miles) in diameter and 20 kilometers (12 miles) in depth, well into the continental crust of the region of about 10–30 kilometers (6.2–18.6 miles) depth. It is the second largest confirmed impact structure on Earth, and the only one whose peak ring is intact and directly accessible for scientific research.
The crater was discovered by Antonio Camargo and Glen Penfield, geophysicists who had been looking for petroleum in the Yucatán Peninsula during the late 1970s. Penfield was initially unable to obtain evidence that the geological feature was a crater and gave up his search. Later, through contact with Alan Hildebrand in 1990, Penfield obtained samples that suggested it was an impact feature. Evidence for the impact origin of the crater includes shocked quartz, a gravity anomaly, and tektites in surrounding areas.
In 2016, a scientific drilling project drilled deep into the peak ring of the impact crater, hundreds of meters below the current sea floor, to obtain rock core samples from the impact itself. The discoveries were widely seen as confirming current theories related to both the crater impact and its effects. A 2020 study concluded that the Chicxulub crater was formed by an inclined (45–60° to horizontal) impact from the northeast.