Near Alice Springs within Australia there are a number of interesting geologic features.
As an example, look at this fold and thrust belt, where two billion years of geology are
exposed.
However, there is also something far more spectacular nearby.
What you are looking at is a magnificent 5 kilometer wide ring structure which is part
of an impact crater known as Gosses Bluff Crater.
However, this structure merely represents a fraction of the crater's overall size.
This impact crater extends much further outwards, and is 24 kilometers wide.
It formed when a massive comet impacted the continent more than 100 million years ago,
when dinosaurs roamed Australia.
This video will discuss this fascinating impact crater, and discuss how it formed.
The Gosses Bluff impact crater can be found in the south central section of the Northern
Territory in Australia.
Specifically, it is 160 kilometers west of Alice Springs.
The entire complex formed from a massive impact approximately 142.5 million years ago.
At the time, a large 2300 meter or 7500 foot wide comet was on a collision course with
Earth.
For comparison, this comet contained about one third the volume of the comet which was
recently visited by a European Space Agency probe.
This mass of icy material and dust likely originated in the outer reaches of the solar
system, beyond the orbit of Neptune in an area of space called the Kuiper Belt.
During the formation of the solar system, heavier elements and compounds largely stayed
relatively close to the sun, while lighter compounds such as water, ammonia, and methane
were present further away.
Thus, masses of these compounds along with dust particles merged together more than 4
billion years ago to form comets.
Unlike planets close to the sun, these comets had highly elliptical orbits.
They were highly elliptical due in part to a mathematically proven but yet to be overserved
planet 9 with a mass of approximately 6 times that of Earth which exerts a strong gravitational
pull on objects in the outer solar system.
Thus, as the comet approached the inner solar system, it was further accelerated to speeds
not possible for asteroids originating in the asteroid belt.
For several weeks before it impacted, a beautiful comet would have been visible in the night
sky.
As this comet entered the upper atmosphere of Earth, it was traveling at 40 kilometers
per second or 89,000 miles per hour.
At the time, Australia was located within the Antarctic Circle, and was connected to
Antarctica and ancestral New Zealand.
Despite its location this far south, Australia averaged 10 degrees Celsius warmer than it
is today.
Numerous large reptiles, such as 7 meter wide ptesosaurs flew over the land.
Some of these animals likely looked upwards and saw a bright streak of light travel across
the sky.
Mere moments later, this comet impacted the surface, generating an explosion equivalent
to the detonation of 755,000 megatons of tnt.
This created a large fireball which expanded outwards to 27 kilometers in every direction.
Due to the immense thermal radiation associated with this fireball, everything within a 450
kilometer radius ignited which started a vast wildfire.
As the shockwave pushed outwards from the center, a magnitude 8.5 earthquake was generated
which was felt by all creatures in a 1600 kilometer radius.
The boom created by this highly energetic explosion was so loud that it was heard across
the entire planet.
Large fragments of rock ejected into the atmosphere from the impact later fell back down, starting
more wildfires.
Ash from the impact was deposited around the planet, where it fell like rain.
As the vast quantity of ash and dust cleared, a 24 kilometer wide and 5 kilometer deep impact
crater became visible.
In the thousands of years following this impact, the underlying crust at the deepest part of
the impact crater began pushing upwards.
Thus, the center of the impact crater was uplifted by more than 4000 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 structure which is the visible ring seen at Gosses Bluff today.
I hope that you enjoyed this video!
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