NWT appears to lose claim to world’s oldest rocks

What’s 130 million years between friends?

Blink and you’d miss it, but that’s the difference between the estimated age of some rocks in the Northwest Territories and rock newly analyzed in northern Quebec.

The bad news? The NWT rocks, at 4.03 billion years old, may now be at best second in the all-time list of Earth’s oldest rocks. The Quebec rocks, reported this week at 4.16 billion years old, appear to be the new title-holders.

Being home to the world’s oldest known rock – the Acasta gneiss, in the Canadian Shield along the Acasta River – has been one of the NWT’s various claims to fame.

Companies have named themselves after it and multiple entrepreneurs have tried to sell the rocks online, marketed as the oldest you can get.

Mark Brown, a prospector, began selling Acasta gneiss rock online more than 15 years ago. He couldn’t be reached for comment this week.

Walt Humphries, another Yellowknife prospector who previously told the CBC he once sold samples of the rock to pay for the costs of staking a claim in the area, said he would “let the scientists argue this one out.”

“If it does get accepted then we are the second-oldest, which is OK,” Humphries told Cabin Radio by email.

“At the age of four billion, a few million here or there doesn’t matter much.”

There is still some hope that the NWT’s hold on the title.

It’s theoretically possible that an even older example of rock can be found elsewhere in the territory having lain undiscovered to date.

Meanwhile, techniques used to date rocks and other objects tend to be refined over time – and a lot depends on the technique applied in any one instance.

In the Quebec example, the rock in question had previously been dated as either 4.3 billion or 3.8 billion years old – introducing a 500-million-year grey area before the latest research provided a firmer estimate.

The new research in Quebec doesn’t apply precisely the same techniques as those used to date the NWT’s Acasta gneiss, in part because the rock compositions are not the same. With that in mind, it’s also possible to argue that the differing approaches complicate an exact comparison between the two sets of results.

Some materials on Earth appear to be even older than either the NWT or Quebec rocks. A crystal found in Australia, for example, has been estimated at 4.4 billion years in age.