The impact event that ended the age of the dinosaurs occurred 66 million years ago. An asteroid, approximately 10 to 15 kilometers (6 to 9 miles) in diameter, struck the Earth, creating the Chicxulub Crater. Scientists link this collision directly to the global extinction of the non-avian dinosaurs and nearly 75% of all species. The crater marks the Cretaceous–Paleogene (K-Pg) extinction event boundary.
The Core Answer: Visibility and Location
The simple answer to whether the crater can be seen is no; it is not visually accessible from the surface. The Chicxulub structure is a buried impact crater, covered by millions of years of accumulated sediment. The location was a shallow sea at the time of impact, and post-impact, layers of limestone and marine deposits covered the scar.
Today, the crater is located beneath the Yucatán Peninsula in Mexico, centered partly on land and partly beneath the Gulf of Mexico. The structure is estimated to be 180 to 200 kilometers (110 to 120 miles) in diameter, making it one of the largest confirmed impact structures on Earth. The burial depth varies, but the crater is covered by hundreds of meters to more than a kilometer of rock.
The structure’s morphology is preserved, including a feature known as a peak ring. This peak ring is a circle of uplifted, fractured rock inside the crater basin. It formed when the ground briefly behaved like a liquid and rebounded after the initial excavation. Chicxulub is the only large crater on Earth with an intact, accessible peak ring, which scientists study to understand large-scale impact mechanics.
Unearthing the Invisible: Scientific Discovery
Because the crater is not visible, its discovery and confirmation required specialized geophysical techniques. Initial evidence came from petroleum exploration in the late 1970s, which revealed a buried, semi-circular feature on the Yucatán Peninsula. Geophysicists recognized the pattern as an anomaly in gravity and magnetic field data, though it was initially misinterpreted as a volcanic center.
The structure’s true nature was confirmed through the analysis of core samples and advanced subsurface mapping. Gravity mapping revealed a circular pattern of gravitational difference created by the impact structure’s dense rock. Scientists used seismic imaging, which sends sound waves into the earth and records the echoes, to create detailed, three-dimensional images of the buried crater’s layers and peak ring.
Scientific drilling projects, such as those conducted by the International Ocean Discovery Program (IODP), were essential for obtaining physical proof. These projects drilled deep into the crater, particularly into the peak ring, to retrieve rock cores. The cores contained shocked granite and impact melt rock, providing definitive physical evidence that the feature was a hypervelocity impact crater.
Geological Footprint: Evidence of the Impact
The impact launched a large amount of material high into the atmosphere, creating a geological signature found in rock layers around the globe. This worldwide layer marks the K-Pg boundary and is the most compelling evidence linking the Chicxulub event to the mass extinction.
One characteristic marker is the Iridium layer, a thin band of clay found worldwide. Iridium is rare in the Earth’s crust but common in asteroids, making the enriched layer a chemical fingerprint of the extraterrestrial impactor. This Iridium anomaly, sometimes 160 times higher than background levels, was distributed globally as dust and vaporized asteroid material settled back to Earth.
Other materials ejected from the impact site include shocked quartz and tektites. Shocked quartz grains feature unique, parallel planes of deformation, or lamellae, caused by the extreme pressure of the impact event. Tektites are small, glass spheres formed when molten rock was flung into the atmosphere and cooled rapidly. These materials, found in K-Pg boundary layers across the planet, confirm the scale of the impact 66 million years ago.
Modern Access and Viewing the Legacy
While the crater remains buried, its geological legacy is visible on the surface of the Yucatán Peninsula as a ring of sinkholes called cenotes. The impact fractured the underlying limestone bedrock, creating a circular zone of highly permeable rock around the crater’s rim.
Groundwater preferentially dissolved the weakened limestone in this fracture zone, causing the overlying rock to collapse and form water-filled sinkholes. This semi-circular belt of cenotes directly outlines the underground crater rim, acting as a surface expression of the buried structure. Visiting these cenotes allows interaction with the crater’s indirect effects.
Educational centers and museums in the region, particularly in cities like Mérida and nearby Progreso, offer access to the scientific findings. These sites often display core samples taken from the crater and use geophysical maps to illustrate the structure of the impact zone. Travelers can visit the town of Chicxulub Puerto, the coastal community nearest to the crater’s center, to be geographically close to the site of this world-changing event.