Scientists say that the Earth has about 190 major meteor craters on its surface. Despite having so many impact craters, scientists only know the age of a few of them. A team of scientists recently studied the Yarrabubba meteor crater in Australia and were able to determine that the crater was 2.229 billion years old.
That makes it the oldest crater currently known. It took the crown of the oldest crater from the Vredefort Dome crater in South Africa with scientists saying the Australian crater is 200 million years older. Scientists are studying crater and trying to date them in an attempt to see what sort of role they played in the environmental development of the planet.
Scientists are trying to determine how a meteor impact might relate to the formation of the continents. Science also wants to know when meteor impacts declined to the point where life could emerge. The Australian crater the team studied is in a very remote part of Western Australia and is believed to have been 70km across. It’s so old that it doesn’t look much like an impact crater.
It’s major features have been weathered away by wind, rain, and other forces leaving only overgrown rocky outcrops according to the team. The weathered remains prevented scientists from dating it with the most common form of crater dating using what’s called a “melt sheet.”
The team instead searched for rocks that could be used to date the events. The specific type of rock has the minerals zircon and monazite inside that contain uranium and lead. The ratio of those can be used to determine the age of the rock. Crystals melted by the impact were used to date the crater.