25km meteor crater in rugged Canadian terrain remained hidden for 390 million years

In 2024, an amateur astronomer found a large pit in Quebec, Canada, while browsing through Google Maps to plan a camping trip. It formed a perfect ring spanning 25 kilometres in diameter and centred around Lake Marsal. It looked too huge to be a regular pit, and so Joël Lapointe contacted French geophysicist Pierre Rochette, who believed that it was a crater made by an asteroid or a comet. Now, findings have confirmed that it is a 390-million-year-old crater from a meteor.

To learn about the origin of the large ditch, scientists retrieved and tested samples. There were a few things that could prove its extraterrestrial origin. One of them was a mineral called zircon, which is formed during meteor impacts. However, it was not enough, and so a team of researchers went to the site to examine the pit. They were looking for evidence of shock metamorphism, something that "occurs due to the immense pressures created by asteroid or cometary impacts, or nuclear explosions", Gordon Osinski, professor of planetary geology at Western University, told Live Science.

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Osinski and other geologists were specifically looking for signs of shockwaves that would have passed through the ground of an asteroid or meteor were involved. Osinski said travelling to the crater was "one of the most arduous expeditions" he had ever taken. "The terrain was incredibly rough and rugged, plus [there were] lots of bugs." However, the ordeal bore fruit when they found what they were looking for - shatter cones, depicted by grooves or lines in the rock's surface.

Signs of impact crater in Canada

An impact event triggers an extreme rise in temperature and pressure as well, leading to the formation of melt rock. Scientists found big cliffs of it, proving an ancient impact. The last time a meteorite crater was discovered in Canada was in 2010. The latest crater discovered has been named Uhaachatik Crater, and the team will present their work at the Annual Meeting of the Meteorological Society in Germany next month.