In the northwest of Greenland, there is a 31-kilometer impact crater named Hiawatha that has puzzled scientists for years. Dating the giant structure has been difficult, but now it seems that two separate teams of researchers, working with two different methods, have reached the same conclusion about the age of this crater. Rather than the youngish possible age of 13,000 years, the Hiawatha crater is about 58 million years old.

Keep in mind that this rather large impact crater was only discovered in 2015, so it’s not as if we were just wildly wrong for a long time. It’s not easy to see or understand something that is buried under a kilometer of ice after all, so scientists posed several different hypotheses for the crater’s age. That 13,000-year-old possibility would have made the impact responsible for a period of cooling called the Younger Dryas, which lasted 1,000 years.

Instead, it appears that this impact occurred not long after the much larger Chicxulub impact that wiped out the dinosaurs, meaning it would have caused even more problems for an already burdened climate and ecosystem. Not to mention that since this particular region wasn’t covered in an ice sheet at the time of the impact, the local flora and fauna would have been devastated. What we call the Arctic today was then lush, temperate rainforest. Earth just couldn’t catch a break back then, it seems.

To date this impact, a team working out of the Natural History Museum of Denmark heated up grains of sand and analyzed the argon gas that was released. And the Swedish Museum of Natural History used uranium-lead dating on rock samples. Both returned the age of 58 million years. Michael Story from the Denmark group stated: Dating the crater has been a particularly tough nut to crack, so it’s very satisfying that two laboratories in Denmark and Sweden, using different dating methods arrived at the same conclusion. As such, I’m convinced that we’ve determined the crater’s actual age, which is much older than many people once thought.

Next up, the teams intend to work out just what affects the impact had on the climate. This work appears in the journal Science Advances.

More Information

University of Copenhagen press release

“A Late Paleocene age for Greenland’s Hiawatha impact structure,” Gavin G. Kenny et al., 2022 March 9, Science Advances