Amateur astronomer discovers massive 390-million-year-old impact crater in Quebec

In 2024, a Quebec amateur astronomer was doing something mundane—searching satellite imagery for a good campsite—when he noticed something that had escaped professional geological surveys for nearly four centuries of millions of years: a perfect ring, 25 kilometres across, encircling Lake Marsal. The shape was too regular, too deliberate, to be natural. He reported what he'd found.

Geologists took the observation seriously enough to mount an expedition. The following year, in 2025, they reached the site by floatplane and began examining the terrain around the lake. What they discovered confirmed the amateur's hunch: shatter cones, the telltale fractured rock formations that form only under the extreme pressure of a meteorite impact. The evidence was unambiguous. Lake Marsal sits inside an impact crater roughly 390 million years old.

The crater had been there the entire time—a scar from the Devonian period, when the continents were still rearranging themselves and life was learning to walk on land. Yet it had gone unnoticed by the scientific community, invisible in plain sight beneath forest and water, until a person with a computer and curiosity happened to look at the right satellite image and recognize what he was seeing.

What makes the discovery notable is not just that it happened, but how it happened. Professional geologists have tools and training that amateurs lack, but they also have constraints: limited budgets, competing priorities, vast territories to survey. An amateur astronomer with access to freely available satellite imagery and time to browse it methodically found something the professionals had missed. He was not looking for impact craters. He was looking for a place to camp. The crater revealed itself to someone who was paying attention.

The shatter cones confirmed the impact's reality. These are cone-shaped fractures in rock that radiate outward from a central point, created only by the shock waves of a collision at cosmic speeds. They are the signature of an ancient violence, preserved in stone. Their presence at Lake Marsal meant that 390 million years ago, a meteorite struck this patch of what is now Quebec with enough force to reshape the bedrock beneath it, leaving a circular depression that would eventually fill with water and become a lake.

The finding underscores a shift in how science works in the age of satellite data and digital tools. Citizen scientists—people without institutional affiliation or formal credentials—can now access the same imagery that professional researchers use. They can spend hours examining terrain that a geologist might never have time to study. They can notice patterns. They can ask questions. And sometimes, they find things that matter.

The crater at Lake Marsal will now be studied more thoroughly. Geologists will want to understand the impact's size, its age more precisely, what it tells us about the meteorite that created it, and what effects it had on the landscape and life around it. But the discovery itself is already complete. A person looking at a screen in Quebec saw something real, reported it, and changed what we know about the ground beneath our feet.