24 January 2020

Scientists recently announced confirmation of the world's oldest impact site, found east of Perth in western Australia. It's 2.2 billion years old. It's not really a crater after so long, It was found because of geophysical anomalies in the area.

Interestingly, it's thought the Earth was undergoing a "Snowball Earth" phase at the time, with pole-to-pole glaciation. They theorize that the impact of this meteorite could have triggered greenhouse gasses to start warming the planet and melting the ice.

Arizona's oldest rocks are schists that date to 1.6 billion years. One of them is the Pinal Schist named for a location in our county. The other Arizona schist of that age is at the very bottom of the Grand Canyon.

When this meteorite landed, Arizona was under the ocean, and located at approximately the South Pole.

You can find the BBC article on the impact site at: https://www.bbc.com/news/world-australia-51201168