What you are looking at is an aerial view of a rather unknown circular feature in the
tundra of northeast Canada.
Despite its appearance, it is not a glacially formed lake from the last ice age.
Rather, it is a near perfectly shaped impact crater known as Pingualuit Crater.
Measuring 3.44 kilometers wide, this recent impact crater now contains what is claimed
to be the world's freshest lake.
This video will discuss the overall crater, when it formed, and mention how frequently
such large impacts occur on the planet.
The Pingualuit Crater can be found in the far northern section of Quebec.
Specifically, it is 47 kilometers south of the small town of Kattiniq.
Within Quebec, there is an unusually high concentration of large impact craters.
As an example, here are the Clearwater craters, which formed from two different impact events
220 million years apart.
So, why does this area contain seemingly so many craters?
In this section of Canada, the majority of rock is 2 to 3 billion years old.
Since these rocks formed, there has been no major volcanic activity or deformation of
the rock.
Thus, any impact craters younger than 1 billion years have remained in the relatively intact
ancient landscape.
Therefor, the concentration of impact craters in Quebec is not high, as large impacts occur
at a similar frequency on the rest of the planet but whose craters have largely been
overlaid and buried so they are not recognizable.
The Pingualuit Impact Crater formed from a recent impact approximately 1.4 million years
ago.
At the time, a medium sized 205 meter or 672 foot wide asteroid was on a collision course
with Earth.
This asteroid was not particularly dense, which relates to its formation 4.5 billion
years ago.
In the early solar system, particles of rock the size of sand and cobbles merged together
due to the force of gravity, forming small asteroids.
Although many of these asteroids went on to become larger bodies of rock such as planets
and larger asteroids, other remained.
Known as chondrites, these types of asteroids when viewed up close contain numerous small
spheres of material clumped together.
More than 85% of all meteorites which enter the earth's atmosphere are chondrites.
As this asteroid entered the upper atmosphere, it was traveling at 17 kilometers per second
or 38,000 miles per hour.
Continuing onwards, it began to break up at an altitude of 50 kilometers.
Only a few seconds later, large fragments of this asteroid struck the ground in a 300
meter radius.
This impact released an immense amount of energy, equivalent to the detonation of 545
megatons of tnt.
As a large fireball was generated, an immense amount of snow from the ice sheet which overlied
this section of Canada was instantly vaporized.
If you were to be standing 10 kilometers away, a 1600 kilometer per hour shockwave would
impact your location.
Although there were few if any plants at the time in the landscape, anything within a 30
kilometer radius instantly caught on fire.
Further away, at a distance of 50 kilometers, fine particles of ash and impact glass called
tektites would begin to rain down, eventually depositing a 6 millimeter layer of material.
After the dust had cleared, the size of the resulting impact crater became clear.
A nearly circular crater, measuring 3,440 meters wide and 430 meters deep had been constructed.
Although some fragments of this asteroid can be found scattered throughout the landscape,
much of it was pulverized.
In the more than 1 million years since this impact, the ice has receded, and a layer of
sediment filled in 30 meters of this deep crater.
Today, this crater lake contains very pure freshwater which is even host to a species
of fish called the arctic char.
So, how often does an impact of this scale occur on the planet?
Its a scary thought, but an impact of this scale occurs about once every 50,000 years.
I hope that you enjoyed this video!
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