What you are looking at is a satellite view of a massive circular feature within Canada
which is sometimes referred to as the eye of Quebec.
This feature is no ordinary lake.
It measures an impressive 72 kilometers wide, and is in fact an ancient impact crater.
Known as Manicouagan Reservoir, it is the 6th largest impact crater on the planet.
This video will discuss the overall crater, when it formed, and mention how a large mountain
formed in the center of this vast crater.
The Manicouagan Resevoir impact crater can be found in central Quebec.
Specifically, it is 415 kilometers north northeast of Quebec City.
The entire complex formed from a massive impact approximately 214 million years ago.
At the time, a large 5 kilometer or 3 mile wide asteroid located in the asteroid belt
between Mars and Jupiter was on a collision course with Earth.
This asteroid was unusually dense, as it was considered to be an M type asteroid made up
of primarily iron and nickel, much like the asteroid which formed meteor crater in Arizona.
As this asteroid entered the upper atmosphere, it was traveling at 28 kilometers per second
or 63,000 miles per hour.
Animals who lived on the planet, including early dinosaurs and giant flying reptiles
known as pterosaurs may have looked upwards and seen a bright streak of light travel across
the sky.
Only a few seconds later, this asteroid impacted the ground in what was the north central section
of the supercontinent Pangea, generating a massive explosion equivalent in energy to
32 million megatons of tnt.
This explosion created a giant fireball which vaporized anything in a vast radius including
billions of ancient plant and animal lifeforms.
Due to the immense amount of released energy, rocks at up to 9 kilometers beneath the impact
melted, thus becoming a large pool of molten rock.
Back on the surface, if you could merely see the fireball, it would be too late as everything
around you would instantly catch on fire due to the immense thermal radiation.
Further away, at distances of up to 1500 kilometers, trees were flattened and animals were knocked
off their feet by the generated shockwave.
Even if you were to be 2,000 kilometers away from the impact, you would still experience
the equivalent of a strong magnitude 4 earthquake and a 144 kilometer wind.
Simultaneously, large fragments of rock ejected by this impact went high into the atmosphere,
before raining back down as glass and superheated debris.
Many of these went on to start large wildfires over a wide swath of the planet.
As the dust cleared, the size of the crater formed by this event finally became visible.
In total, the crater generated by this impact measured an impressive 100 kilometers or 62
miles wide.
This crater carved into a group of 1.2 billion year old high grade metamorphic rocks called
gneiss.
You might hear this figure and think, “but wait, you said the crater was 72 kilometers
wide earlier in the video”.
The reason for this is that the outside of the crater slowly eroded away, and was overlaid
by significant sediment which caused the impact structure to shrink over time.
I want to note that the rocks at the center of the impact were surrounded by such a large
volume of adjacent molten rock that they took an impressive 4,000 years to entirely cool.
In the thousands of years following this impact, the underlying crust at the deepest part of
the impact crater began pushing upwards.
A good analogy is removing the top third of a sponge in water.
It will still float, and the removal of this section will cause it to rebound upwards.
Thus, the center of the impact crater was uplifted by more than 1000 meters, forming
now called Mount Babel and the surrounding dome like island.
Despite the vast scope of the impact which had just occurred, it did not end up having
any long term impacts on the global scale.
Although a several year impact winter did occur, it did not lead to any widespread mass
extinctions.
It was deadly for the center of Pangea, but only an inconvenience to life on the rest
of the planet.
Today, Lake Manicouagan serves as a large reservoir and is one of Quebec’s most important
regions for Atlantic salmon fishing.
If you visit this crater, you might find some unusual rocks associated with its formation.
In addition to shatter cones, you could find a rock type called suevite, which is a variety
of breccia formed exclusively from impact events.
I hope that you enjoyed this video!
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