A previously unrecognised impact structure roughly 25 kilometres across has been identified in the Quebec wilderness, after an amateur astronomer searching online satellite maps for a campsite noticed a circular feature near Lake Marsal.
There are roughly 200 confirmed impact structures on Earth, and geologists estimate that hundreds more remain undiscovered. This is a large addition to the confirmed list.
In 2024, while preparing for a trip to the remote Côte-Nord region, the astronomer suspected the depression might be an impact crater and contacted experts in both Europe and North America.
Those questions led a team of French researchers to list the lake area as the centre of a possible 11th known impact structure in Quebec, at a meeting of the Meteoritical Society in 2024. That in turn drew in Gordon Osinski, a planetary geologist at Western University and director of the Impact Earth database, who was initially sceptical but organised an expedition to the site in October 2025.
Getting there was the first problem. The floatplane could not reach the shore, and the researchers had to wade across 50 metres of water carrying their equipment. The terrain was rugged, swampy, full of insects and covered in what Osinski described as "deep, twisty, gnarly vegetation". Despite fieldwork on six continents, he described the conditions as among the most challenging he had experienced.
Previous geological mapping had suggested that the breccia rocks in the area were the product of a diatreme, a funnel-shaped volcanic feature formed by explosive eruptions of magma.
By the second day, the team had identified shatter cones in many rock outcrops, a structure that forms under the intense pressures of an impact. "It's the only unequivocal evidence of an impact event that you can see in the field with the naked eye," Osinski said.
The object that struck was large enough to produce a complex crater 25 kilometres across, with a central uplift and tall cliffs marked by columnar jointing. Rock samples indicate the crater formed about 390 million years ago, roughly 100 million years before a surge in cratering on Earth that may be associated with collisions in the asteroid belt.
After consultations with the Innu Council of Ekuanitshit, the team is calling the crater Uhackatik. It considers the impact origin essentially confirmed, with formal recognition expected from a Meteoritical Society committee when it next meets. It is the largest impact crater discovered since the 31-kilometre Hiawatha structure was found in 2018.
The sequence is worth stating plainly. Geologists went to the site, examined the rocks in the field and concluded it was volcanic. Someone who was not going to the site, and who was looking for somewhere to pitch a tent, saw that it was a circle.
The difference was distance. At ground level a 25-kilometre structure presents as terrain: swamp, outcrop, lake, hill. Its shape is available only to an observer far enough away to lose the detail, which in practice meant a satellite and a laptop.
This implies an unhelpful relationship between the size of a thing and the ease of noticing it. Small features are found by looking closely. Large features are found by standing further back. Very large features require an observer who is not looking for them at all, and who ideally has other plans for the weekend.
Several hundred impact structures are believed to remain unidentified. If the pattern holds, they are not hidden. They are simply being presented at a scale nobody has thought to step back from, and are being walked over by specialists who correctly describe the rocks in front of them.
The Department of Unnecessary Research has begun its own survey at the greatest available distance, and reports that the largest circular feature so far identified is the Earth.