The history of the Earth is riddled with geological violence. Massive volcanic eruptions have been heard around the world, asteroid impacts have nearly wiped out all living things, and a planetary collision that could have ended the planet before it began are just a few examples of Earth’s violent past.
The scars of Earth’s formation and lifespan are hard to find after having so many years to heal, but scientists can still spot some of them. Today, we’re going to look at the largest crater on Earth.
We’ll show you just how big it is, how it formed, and where it’s located. You’ll learn just how lucky humans are to have developed at all!
What is a Crater?
A basic definition of a crater is a depression in the surface of a celestial body, often bowl-shaped, formed by an impact or explosion. For example, the moon is covered in impact craters from small asteroids or comets that have slammed into its surface.
We can also find craters that stem from volcanic eruptions, like that at Mount St. Helens. In short, craters can be formed in many ways, but the largest craters on the Earth tend to be formed by meteorite impacts.
One would think that a massive meteorite impact would leave a definitive and obvious trace. However, most of the largest impacts happened millions or billions of years ago, long before humans.
Fortunately, we now have the tools to find impact craters and measure them using modern tools, like satellites. We can look at eroded sites and use evidence from the surrounding areas to determine their size, age, and cause.
Now that we know what makes a crater, we can start to consider the largest on the planet.
What Kind of Craters Are We Measuring?
The vast majority of large craters on the Earth were caused by meteorites hitting the planet. Thus, impact craters are the ones that we will be looking at in this case since they make up just about all of the largest craters in the world.
Although volcanic eruptions can cause craters, they rarely exceed more than a few miles in diameter. The largest volcanic crater, the Ngorongoro Crater, is just about 10 miles across. However, even that is not truly a crater, but actually a caldera.
The difference between craters and calderas is significant because a crater forms from the expulsion of material from an area. However, a caldera forms when a volcano erupts, and then the land collapses since the underlying magma chambers are empty.
The largest caldera on Earth is the Apolaki Caldera, an area measuring 93 miles in diameter, twice that of Yellowstone Caldera. The craters we’re going to examine are even larger.
What is the Largest Crater on Earth?
The largest crater on Earth is Vredefort Crater, and it measures 99.41 miles across or 160 kilometers. The crater is located in present-day South Africa. Now, you might say to yourself, the Chicxulub crater is 110 miles in diameter. What’s going on here?
Simply put, 99.41 miles is the diameter measurement attributed to the crater today. The crater has undergone significant erosion. The original measurement for this crater is believed to be upwards of 190 miles in diameter upon its formation. Also, it was about 24 miles deep on impact.
The crater has largely eroded over time, as it happened over 2 billion years ago. Based on what is left, scientists have stated that the asteroid that hit there was 6 to 9 miles wide. With that said, it is bigger than the one that killed off the dinosaurs but long before it happened.
So, this is the largest crater on Earth, but it’s not one that you can stand on the edge of and peer across a hundred miles. The reason is that the meteorite that formed this crater struck the planet over 2 billion years ago. Thus, the crater itself has greatly eroded over time. Yet, scientists can still find evidence of this massive impact.
Scientists know that this was an impact rather than a volcano for several reasons. For example, they found shatter cones in the bedrock of the Vaal River. These geological features form when rocks are subjected to immense pressures from meteorite impacts and nuclear explosions.
Also, distortions in the erosion-resistant rock formations that predated the impact provide insight into the initial strike zone. The cross-section of the crater’s geological area, along with lingering evidence of the impact’s ejecta, all provide valuable insight into the creation of this crater.
Based on the available evidence, scientists believe that the asteroid that caused this impact crater was between 6.2 and 9.3 miles in diameter. That makes it one of the largest impactors that have struck the planet.
Was the Largest Crater on Earth from the Dinosaur-Killing Asteroid?
No, the largest crater on Earth was from an event that preceded the end of the dinosaurs by a billion years. The Paleogene extinction was an event that killed off non-avian dinosaurs on the planet. This extinction event was heralded by a massive asteroid impact.
The asteroid is known as the Chicxulub impactor. Scientists believe the asteroid was about 6.2 miles in diameter when it struck the planet. The impactor landed in the Yucatan Peninsula in modern-day Mexico.
Interestingly, the Chicxulub crater is relatively young compared to the Vredefort crater, so it has helped scientists understand the event a bit better. The crater is about 110 miles in diameter and measures about 12 miles in depth.
Interestingly, another proposed cause of the dinosaurs’ extinction was a period of intense volcanism in modern-day India. According to some scientists, the Deccan Traps were highly active at the same time that the Chicxulub impactor struck. Some studies have even claimed that the massive eruptions were directly caused by the impact of the Chicxulub asteroid, making its effects even more devastating.
The largest crater on Earth was not from the event that killed the dinosaurs. In fact, it was most likely far more damaging to the planet despite not causing a major extinction event. Although we have plenty of evidence proving the existence of the greatly diminished Vredefort crater, future studies could grant further insight into the event.
Where Is the Vredefort Crater Located on a Map?
The crater site is in the Free State province of South Africa. Only part of the crater ring can be seen because 300 million years ago some rock formations obscured it. Also, part of the crater has become farmland. The Vredefort Dome is the crater’s central uplift. In 2005, it was added to the list of UNESCO World Heritage Sites for its geologic interest.
The photo featured at the top of this post is © Virrage Images/Shutterstock.com
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