Why WA's ground is some of the oldest on Earth

Ever heard someone blame Perth's tired, sandy soil on it being "old"? A world map shared to r/perth on Friday shows just how old. It highlights the parts of the planet sitting on rock more than 539 million years old, and Western Australia is covered in it.

The post, shared from r/Maps, notes almost a quarter of the world's land is this ancient, and that much of WA is about 3 billion years old.

Cratons: the old hearts of continents

Geologists call these ancient, stable blocks of crust cratons. WA has two of the world's best known: the Yilgarn Craton, which underlies much of the southern half of the state including the Wheatbelt and Goldfields, and the Pilbara Craton in the north. Both are made largely of rock formed in the Archean eon, more than 2.5 billion years ago.

Bentley

The Flying Spur. A limousine that loves to drive.

Sink into hand-stitched luxury in the back, or take the wheel and feel it surge. The Flying Spur is the rare sedan that pampers and thrills in equal measure.

Learn more

Because these regions have sat quietly for so long, untouched by the mountain-building and glaciers that renewed soils elsewhere, their soils are heavily weathered and low in nutrients. That's one reason WA's native plants are so good at surviving on very little.

Image: Gretarsson via Wikimedia Commons (CC BY 4.0), based on Landsat 5 data.

Earth's oldest crystal

WA also holds the oldest known piece of Earth. In the Jack Hills, in the Murchison region, scientists found tiny zircon crystals that have been dated to about 4.4 billion years old. A 2014 study in Nature Geoscience led by John Valley at the University of Wisconsin-Madison confirmed one at around 4.374 billion years, using atom-probe tomography to count individual lead atoms.

That makes the crystal only about 160 million years younger than the solar system itself, and evidence that Earth had a solid crust very early on.

And early life

The Pilbara's Strelley Pool area holds stromatolite fossils, layered structures built by microbes, that are among the oldest widely accepted evidence of life on Earth, at roughly 3.4 billion years old.

Coca-Cola

Frozen Coca-Cola. The coolest way to refresh.

That famous Coca-Cola taste, blended into an icy frozen swirl. On a hot Perth afternoon, nothing hits quite like a Frozen Coke. Pure, frosty refreshment.

Learn more

Image: NASA via Wikimedia Commons (public domain).

Perth Reddit's response? Just one comment so far: "Is that why we are always behind aka 'Wait Awhile'?"

Sources: r/perth thread; EarthSky; Sci.News.

Main photo: Karijini National Park by Phil Whitehouse via Wikimedia Commons (CC BY 2.0). File photo.

More