Joël Lapointe, an amateur astronomer, was looking through satellite maps to identify possible summer campgrounds in Quebec’s Côte-Nord area.
He observed a unique 15-mile circular ring of lakes around Lake Marsal, which was deeply covered by boreal northern forests.
Geological field research began immediately after his observation.
Investigation into the rock and field evidence proved that it was indeed a crater made by an extraterrestrial body some 390 million years ago on the Canadian Shield.
Finding a hidden ring on satellite maps
Geological features too subtle to be seen by those viewing from the Earth’s surface can be discovered via satellite images.
As Lapointe analyzed the satellite coordinates around Lake Marsal, the symmetry created by the surrounding lakes was too obvious to ignore—a 15-mile diameter in a bulls-eye formation.
Symmetry this perfect is seldom a result of glacial erosion.
It became evident that neither erosion nor glacial motion could account for the crater-like depression, so the amateur sent his coordinates to planetary scientists.
It was not long before the geologists realized that a unique field study was required.
The unusual formation suggested the existence of an unknown large impact crater located underneath the centuries-old layers of vegetation and glacial sediments.
Searching for shatter cones in the bedrock
Field geologists carried out a field study of the bedrock outcrops.
The geologists journeyed for miles through the wilderness area near Lake Marsal, searching for some hard proof of the shock pressure produced by the cosmic collision.
No volcanic processes could lead to the formation of such hypervelocity shock waves.
The scientists identified shatter cones, which are distinctive fan-shaped cone fractures, in the rocks of the region; these occur only as a result of an impact by a high-velocity meteorite with the rock on the Earth’s surface.
Testing microscopic mineral shock patterns
Confirmations came after laboratory tests.
The rocks were prepared into thin slices that were subjected to study through the microscope to determine the structure of quartz crystals inside them.
High pressure from the impacts altered the minerals.
The quartz crystals showed features indicating that the bedrock was subjected to high shock pressures.
Normal tectonic processes cannot form shock lamellae.
The existence of these twin structures provided concrete evidence through microscopic examination that such deformations could not be anything but the result of a very fast meteorite.
Mineral analysis confirmed this without any ambiguity.
The geologists identified the Lake Marsal structure as an actual impact crater and not an ancient volcanic crater.
Isotopic dating of a prehistoric Devonian collision
The approximate age of the collision was determined.
Radiometric dating of the molten rock revealed that the impact of the extraterrestrial body occurred about 390 million years ago in the Devonian period.
The size of the asteroid was about half a mile in diameter.
When this body collided with Earth, due to its huge kinetic energy, it vaporized the surface rocks and created a large crater.
Erosion slowly eroded the rim.
Millions of years of wind, rain, and ice age glaciers altered the rim of the crater so much so that today, only the central depression is left.
Uncovering planetary history using open mapping tools
Open mapping tools give citizens the ability to become scientists themselves.
Elevation data from satellites makes it possible for mapping enthusiasts to spot geographical peculiarities over large areas.
Field research will confirm the satellite findings, according to the NASA Earth Observatory.
The joint efforts of the satellite exploration technique and field geology ensure that any impact history found in uninhabited areas will be entered in the records.
The Lunar and Planetary Institute / USRA says that the contributions of amateurs are vital to current geology.
The Lapointe discovery shows that amateurs who analyze public information can make amazing scientific discoveries without laboratory technology.
Accessible satellite technology continues to expand planetary science.
With advancements in high-resolution satellite imagery across the world, professional geologists, along with citizen scientists, can together find long-buried scars caused by space rocks on Earth.
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