Vredefort Crater-The largest verified impact crater on Earth

Vredefort Dome*
UNESCO World Heritage Site
State Party	South Africa
Type	Natural
Criteria	viii
Reference	1162
Region**	Africa
Inscription history
Inscription	2005  (29th Session)
* Name as inscribed on World Heritage List. ** Region as classified by UNESCO.

Vredefort crater is the largest verified impact crater on Earth. It is located in the Free State Province of South Africa and named after the town of Vredefort, which is situated near its centre. The site is also known as the Vredefort dome or Vredefort impact structure. In 2005, the Vredefort Dome was added to the list of UNESCO World Heritage Sites for its geologic interest.

The crater is occasionally known as the Vredefort Dome and the Vredefort Impact Structure. It is estimated that the asteroid that formed the crater was 10 km in diameter. The crater itself has a diameter of nearly 300 km. The crater is over 2 billion years old. Because of erosion it is hard to estimate the original depth and diameter of the crater.

The force of the impact that created the Vredefort crater was much higher than that of the Chicxulub crater. Imagine taking every nuclear bomb in the world and exploding them all at the same time. Now imagine an explosion at least ten times more powerful and you would have an idea of the force that created Vredefort crater. The projectile and much of the immediate target rock would have been vaporized and rocks that were further away would have been melted together. Remnants of this melt still occur in the form of large deposits of a special rock, known as Vredefort granophyre. It is very fortunate for evolution that there was nothing more than microscopic plant life at the time. If an impact event one third the size of this one (Chicxulub) killed off 75% of life on the planet, imagine what the Vredefort impactor would have done.

The Vredefort crater has provided shelter for man for at least 150,000 years. There is ample evidence of that. In Iron Age times, from about the 1300s to 1850, maybe as many as tens of thousands of Tswana people lived in the mountains and hills of the dome, likely because the varied landscape provided shelter and excellent grazing alike. In even more recent times, the area has seen a little gold rush.

Monochrome satellite view of the crater

The Vredefort crater is the largest verified impact event on Earth, but do not forget about Wilkes Land in Antarctica. It is thought to be much larger, but can not be verified at this time because it is buried under 2 km of ice. Vredefort will continue to play an important role in science for the remainder of this century and beyond as students visit the area to study it. As a method of insuring that, the site has been declared a World Heritage site.

There are many interesting articles on the internet about the Vredefort crater. There are a few more related articles here on Universe Today. and Astronomy Cast.