The impact that ended the age of dinosaurs some 66 million years ago was the worst single day that life on Earth has ever endured. A six-mile-wide asteroid called Chicxulub slammed into the waters off what is now Mexico, triggering a mass extinction that killed off more than 75 percent of Earth’s species.

Unfathomably powerful earthquakes rattled and rolled the planet’s crust. Tsunamis more than 150 feet tall pummeled North America’s shores. Wildfires ignited hundreds to thousands of miles away from the impact site, set ablaze by the searing heat of the asteroid’s initial impact plume and the torrents of debris that followed.

Hundreds of sites around the world preserve vestiges of this cataclysm—but at one unusual site in North