Our planet was born around 4.5 billion years ago. To understand this mind-bendingly long history, we need to study rocks and the minerals they are made of.
The oldest rocks in Australia, which are some of the oldest on Earth, are found in the Murchison district of Western Australia, 700 kilometers north of Perth. They have been dated at almost 4 billion years old.
Remnants of deep time
So next time you pick up a rock and some mineral grains rub off on your hand, spare a thought for how long those grains might have been around.
To come to grips with the time scale, imagine the history of our planet was a year long. Earth formed from swirling dust 12 months ago. Any handful of sand you pick up around Perth will contain a grain or two from about ten months ago. Most of Australia’s gold formed seven months ago, and land plants arrived only one month ago.
Two weeks ago, dinosaurs showed up. All of humanity has come in the past 30 minutes. And you? Soberingly, on this scale, your life would last about half a second.
Cryptic geological histories accessed through entombed and matrix geochronometers in dykes