Earth is constantly being pummeled by space rocks. Several tons rain down on the planet each day in the form of dust. And larger strikes have created more visible features, including giant craters. But which of our planet’s extraterrestrial scars is the oldest?

Researchers reported on Tuesday in Nature Communications that they have pinpointed it, in Western Australia. It was caused by an impact more than 2.2 billion years ago.

Intriguingly, that timing roughly coincides with the end of one of our planet’s ice ages. An impact in the ice would have liberated an enormous amount of water vapor, the researchers suggest, perhaps enough to alter Earth’s climate and catapult the planet out of widespread glaciation.

The Yarrabubba impact structure, about a day’s drive northeast of Perth, isn’t much to look at today. The original crater, believed to have been roughly 40 miles in diameter, is long gone.