Surface land is a bit of a misnomer here. While the crust is 4.4B years old in Australia, that doesn't mean all 4.4B years are sub-surface. The top surface ther

Surface land is a bit of a misnomer here. While the crust is 4.4B years old in Australia, that doesn't mean all 4.4B years are sub-surface. The top surface there is new, but there are exposed areas going back billions of years. This is how all fossils are found; the oldest surface is the 1.8M Negev desert, but we constantly find 300M year old dinosaurs sticking out of the sides of river valleys and other eroded areas. My point is that we'd also find evidence of a billion-year-old advanced civilization the same way, and that in Australia in particular, you can go all the way back to the formation of the planet.