Shatter cones confirm a 25-kilometre Quebec crater that earlier surveys called volcanic

A shatter cone is the one field observation that closes the question. The structures form under the intense pressures produced during an impact, and their presence in the outcrops is what argued against a volcanic origin ^[10]. "It's the only unequivocal evidence of an impact event that you can see in the field with the naked eye," Osinski said in an account published by NASA Earth Observatory on September 22, 2026 ^[11][22].

The imagery found a circle; it could not separate the two candidate origins. Earlier geological surveys had interpreted the local breccia as a diatreme, the funnel-shaped pipe of shattered rock left when explosive magma eruptions blow through ^[9]. Someone had to go and look.

Going was hard. The floatplane could not reach shore, so the team waded 50 metres carrying its equipment ^[6]. The ground was rugged and swampy, with what Osinski called "deep, twisty, gnarly vegetation" ^[7], and he said that across years of fieldwork on six continents the area ranked among the most difficult environments he had ever worked in ^[8].

The structure itself is complex: about 25 kilometres across, with a central uplift and high cliffs showing columnar jointing ^[12]. That makes it the largest impact crater found since the 31-kilometre Hiawatha structure in 2018, about six kilometres smaller across than Hiawatha ^[17][21]. A comparable strike on modern Quebec, Osinski said, would cause "regional devastation on a scale that would wipe out major cities and have global climate impacts" ^[13].

Earth has about 200 confirmed impact structures, and geologists think hundreds more are still unidentified ^[1]. Uhackatik, the name the researchers adopted after discussions with the Innu Council of Ekuanitshit ^[15], would be Quebec's eleventh ^[4]. One province would then hold roughly one in eighteen of the world's confirmed craters ^[19]. Quebec may have been struck more often, or its old exposed bedrock may simply make old craters easier to see.

The samples put the impact at roughly 390 million years ago, about 100 million years before a rise in cratering that researchers have suggested may be linked to collisions in the asteroid belt ^[14]. Subtract, and that rise sits near 290 million years ago ^[20].

In my view the imagery half of this search is now open to anyone with a browser and the confirming half is not, so the list of candidate circles will grow faster than the list of confirmed craters. Access is the binding limit, and it binds even for people whose job is visiting craters: Osinski is part of NASA's first Artemis Geology Team and helps train astronauts in geology, and he does not expect Uhackatik to become a training site because reaching it is so difficult ^[18].