Jack Hills

And armed with these long natural clocks, geologists started hunting for the oldest rocks they could find.

In the Jack Hills of Western Australia, out in the remote Outback, scientists discovered microscopic zircon crystals.

And when they used uranium-lead dating on them, the results were mind-blowing.

They dated these Jack Hills zircons to 4.4 billion years old.

4.4 billion.

They are the oldest known minerals on Earth.

Western Australia was our very first spot in Season 1, way back in Episode 10.

More accurately, those episodes covered just a very small corner of Western Australia, the Jack Hills, which hold Earth's oldest crystals, more than four billion years old.

That's January 14th on the Earth calendar.

We have come a long way since then.

But Western Australia is a very large place, and most spots are a bit younger.

So let's zoom out from our old location of the Jack Hills and get our bearings for some new spots.

Western Australia is a land of extremes.

It is the largest state in Australia, holding one-third of the nation's land.