Within Canada, there are a number of large impact craters, such as the 72 kilometer wide
Manicouagan Reservoir.
Another example is a set of two very close craters which formed 180 million years apart.
Looking at all of these craters, you might think that large asteroid impacts only form
near perfect circular craters.
However, as shown by the Messier impact crater on the moon, craters can also be oblong.
Back on Earth, there is another oblong crater located within Canada.
What you are looking at is the impact crater in question, which is known as Mistastin Crater.
The crater lake merely represents a fraction of its overall size.
In total, the crater measures 31 kilometers long and 26 kilometers wide.
This video will discuss the overall crater, when it formed, and mention how a large island
formed in the center of this vast crater.
The Mistastin Lake impact crater can be found in northwest Newfoundland and Labrador in
a remote section of forest.
Specifically, it is 340 kilometers north-northwest of the town of Happy Valley.
The entire complex formed from a massive impact approximately 36 million years ago.
At the time, a large 2.5 kilometer or 1.6 mile wide asteroid 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 much smaller asteroid which formed meteor
crater in Arizona.
As this asteroid approached Earth, it was further accelerated by the pull of the planet's
gravity.
Entering the upper atmosphere, it was traveling at 16 kilometers per second or 36,000 miles
per hour.
However, unlike the vast majority of asteroids, it did not enter the atmosphere at an angle
of 40 to 45 degrees.
Rather, it entered at a much shallower angle of 20 degrees.
At the time, the Earth was a much warmer planet.
During this era, termed the Eocene period, primitive crocodiles and giant tortoises were
just two creatures who lived in the area.
They may have looked upward and seen a bright streak of light travel across the sky.
Only a few seconds later, this asteroid impacted the ground, generating a massive explosion
equivalent in energy to 1.3 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 several kilometers beneath the impact
melted, thus becoming a large pool of molten rock.
Back on the surface, anything within a 500 kilometer radius ignited due to the immense
thermal radiation.
Further away, at distances of up to 650 kilometers, trees were flattened and animals were knocked
off their feet by the generated shockwave.
The molten rock created at the center of the impact was so hot that it took several thousand
years to completely cool.
These lavas created the highest known temperatures ever recorded on the planet, which was 2370
degrees Celsius or 4300 degrees Fahrenheit.
This was hot enough to naturally form cubic zirconia, which can today be found around
the crater's rim.
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
a central peak.
In the many millions of years since, this peak experienced a significant level of erosion,
which transformed it into a partial ring structure now called Horseshoe Island.
Despite the vast scope of the impact which had just occurred, it did not end up having
any long term impacts on the planet.
As a final note, the margin of error on the age of Mistastin Crater puts it within the
known age range of several other large impact craters which formed during a brief timespan
on the planet.
As an example, the 85 kilometer wide Chesapeake Bay Crater southeast of Washington DC formed
35.5 million years ago, which lends the possibility to these large craters forming as part of
a multiple impact event from a fragmented large asteroid.
I hope that you enjoyed this video!
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