What you are looking at is a satellite view of a rather unknown circular feature within the Great
Sandy Desert of Australia. Despite its appearance, this feature is NOT a maar explosion crater, as no
volcanic activity has occurred in the region for many millions of years. Rather, it is one of the
most well preserved impact craters on the planet, which is called Wolfe Creek Crater. It measures
875 meters wide, and 60 meters deep. In its center is a patch of unusually green vegetation,
as the bowl shaped crater provided a natural area for rainwater to pool during the rainy season.
This video will discuss the overall crater, when it formed, and mention its geologic importance.
The Wolfe Creek Crater can be found in the northeast section of Western Australia.
Specifically, it is 130 kilometers west of the border with the Northern Territory of Australia.
This impact crater originated only 120,000 years ago, when a small asteroid was on a collision
course with earth. It measured 15 meters or 49 feet wide, and was an unusually dense iron nickel
meteorite. Asteroids of this composition originated more than 4 billion years ago,
and represents the section of the differentiated core from a much larger asteroid. You might note
that throughout this series on impact craters that many smaller craters formed from iron meteorites,
despite their low distribution in overall meteorite falls. This is not a coincidence, as due
to its density and durability iron meteorites are far less likely to burn up in the atmosphere. A
similarly sized chondrite meteorite would burn up, while an iron meteorite would impact the surface.
As this 14,000 ton asteroid entered the upper atmosphere, it was traveling at 17
kilometers per second or 38,000 miles per hour. Ancient Australian megafauna who lived at the
time including the hippo sized diprotodon and a species of sheep sized echidna may
have looked upwards and seen a bright streak of light travel across the sky. As this occurred,
fragments of the asteroid flew off and part of its mass burned up. Only a few seconds later,
this asteroid impacted the ground in what is now western Australia. As it hit the ground,
a massive explosion occurred, which was equivalent in energy to 540 kilotons of tnt. It may seem
strange that such a large explosion occurred due to only a bus sized chunk of rock, but consider
the formula for kinetic energy. Although the mass is not notably very high, the vast majority of the
resulting energy comes from the meteor's insanely high speed. As this explosion occurred, rocks at
up to 200 meters in depth were instantly deformed by the force of the blast. This explosion created
a small fireball which vaporized anything in the immediate vicinity. Areas 1 kilometer away soon
faced a powerful shockwave, which raced across the landscape at 1460 kilometers per hour. Furthest
out, at distances of up to 5 kilometers away, any existing sparse trees or bushes were flattened.
However, since this impact was relatively small, the energy quickly dissipated after this distance.
After the dust had cleared, the scope of this impact event became clear.
This new crater had a rather circular shape, and measured 875 meters wide and 178 meters deep.
Since then, 120 meters of sand and sediment have blown in from winds, thus filling two
thirds of the crater. Today, Highly rounded fragments of the meteorite which formed this
impact crater can be found in a 4 kilometer radius. On occasion, you might see a rounded ball
of what was originally iron nickel sulfide eroded to a more rusty looking mineral called goethite.
I want to add that many new mineral discoveries are made from meteorite falls.
In the case of Wolfe Creek, a new yellow to green mineral called reevesite was
first identified on an impact fragment. Today, Wolfe Creek Crater can be visited
through a series of dirt and gravel roads in the Australian outback. Using the nearby town of Halls
Creek, this crater is only a 150 kilometer drive away which I have outlined on screen.
If there is water within the crater, you may find an abundance of wild bird
species such as the noisy cockatiel. I hope that you enjoyed this video!
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