Scientists say they've proven these Canadian rocks are the oldest on Earth

Emily Chung · CBC News

· Posted: Jun 26, 2025 2:00 PM EDT | Last Updated: 4 minutes ago

In 2008, Canadian researchers led by McGill PhD pupil Jonathan O'Neil said they'd found the world's oldest rocks, formed 4.3 cardinal years ago successful what is present northwestern Quebec. Such rocks would springiness scientists an unprecedented glimpse into Earth's aboriginal past during its precise archetypal eon, the Hadean, conscionable a fewer 100 cardinal years aft the Earth formed 4.5 cardinal years ago.

But the find was controversial, and different scientists argued that the rocks were simply mixtures of older and younger material, incapable to truly archer america what the satellite was similar astatine that time.

Now, aft much than a decennary of hard work, O'Neil and his squad person done a caller investigation of rocks from the Nuvvuagittuq Greenstone Belt (NGB), a stone enactment located successful Quebec's Nunavik region, astir 40 kilometres southbound of Inukjuak, adjacent to the eastbound enactment of Hudson Bay. 

The recently studied rocks, which formed aboriginal than the archetypal rocks analyzed, are astatine slightest 4.16 cardinal years old, reports a insubstantial published contiguous successful Science. That confirms that adjacent they are from the Hadean, and since the archetypal rocks are adjacent older, and the stone enactment includes "the oldest rocks preserved connected Earth," the survey says.

O'Neil, present a prof of world sciences astatine the University of Ottawa, said that to geologists, rocks are similar books, afloat of chemic records of erstwhile they were formed and the situation astatine that clip – offering clues astir erstwhile the oceans formed, erstwhile beingness began, and erstwhile sheet tectonics started creating the continents. With specified aged rocks, helium added, "We person the accidental to unfastened a caller model connected a clip erstwhile we person astir nary record."

What we cognize astir the Hadean eon

When the Earth archetypal formed, it was a shot of molten lava. And originally, scientists considered the Earth's archetypal eon, the Hadean, to person ended erstwhile the archetypal rocks formed. What's known arsenic the "golden spike," marking the extremity of the Hadean, is besides located successful Canada, astatine the Acasta Gneiss enactment successful the Northwest Territories, which is 4.03 cardinal years old.

Scientists hold connected that day due to the fact that the Acasta Gneiss contains zircons, minerals that springiness precise reliable ages for rocks reasonably easy utilizing a method called isotopic dating. The method relies connected the changeless complaint of decay oregon radioactive materials and uses those arsenic a clock.

While scientists utilized to deliberation determination were nary rocks during the Hadean, O'Neil said, they've changed their minds arsenic a effect of much and much grounds uncovered successful the past 20 years, including zircons formed 4.4 cardinal years agone successful Australia. (These zircons, which are tiny soil grains embedded successful sedimentary rocks, are excessively tiny to be considered rocks themselves.) 

Such tiny mineral grains can't springiness astir arsenic overmuch accusation arsenic an full stone — only thing equivalent to "maybe a page," O'Neil said. With an full rock, "we whitethorn person a section oregon [an full book]," O'Neil said.

In the past decennary his squad has recovered intriguing grounds that the NGB rocks were formed connected the water level and whitethorn amusement immoderate early traces of life and possible grounds of sheet tectonics  — but the "unfortunate" property controversy, arsenic O'Neill describes it, has near them incapable to accidental for definite that these are things that happened during the Hadean. 

Why truthful controversial?

The Nuvvuagittuq Greenstone Belt is made of an unusually airy basalt, a benignant of stone often formed connected the water floor. Unfortunately, basalt doesn't incorporate zircons, truthful geologists can't archer its property utilizing the astir reliable isotopic method available.

Instead, O'Neil and his squad turned to a method called samarium-neodynium dating, suitable for rocks older than 4 cardinal years old.

"This has been applied connected rocks from the satellite and connected rocks from Mars — it's conscionable determination are nary rocks connected Earth that are aged capable to usage that technique, but possibly from the rocks from bluish Quebec," O'Neil said.

In addition, dates from 2 antithetic isotopic "clocks" didn't hold successful that earlier study. O'Neil thought that was due to the fact that 1 of the 2 clocks was much susceptible to events that happened to the rocks agelong aft they formed, giving a younger date.

But different scientists thought it was a motion that the stone was a substance of older and younger material.

Graham Pearson, a University of Alberta prof who has been dating and tracing immoderate of Canada's oldest rocks for astir the past 15 years, said, "It's truly casual to get the incorrect day connected rocks utilizing immoderate approach."

But helium added that successful the lawsuit of O'Neil's archetypal study, which helium wasn't progressive in, immoderate assumptions were made betwixt the relationships of antithetic rocks that allowed for 2 ways of interpreting the data.

New, much convincing proof?

To resoluteness the controversy, O'Neil's squad analyzed a portion of neighbouring stone from the NGB. The recently analyzed rock is an intrusion, oregon liquid magma that had squeezed its mode betwixt the cracks of the archetypal stone astatine a aboriginal day and past solidified. By definition, that makes it younger than the archetypal rock.

In the caller analysis, funded by the Natural Sciences and Engineering Research Council of Canada and the authorities of Ontario, some isotopic clocks agree, O'Neil said, "giving the aforesaid nonstop property astatine 4.16 cardinal years old" for that newer rock. 

Martin Bizzarro, a Canadian prof astatine the University of Copenhagen, was among those who thought mixing was down the 2008 results. He acknowledged that the statement of clocks successful the caller survey is "rare." But helium told CBC News successful an email, "I don't deliberation [the data] conclusively beryllium the rocks are Hadean" arsenic determination are different explanations "given the complexity of aboriginal Earth processes."

Meanwhile, Pearson said helium is convinced by the caller data, fixed the assortment of techniques O'Neil and his squad usage and their "really cautious study."

O'Neil hopes the caller information volition springiness different scientists assurance that the rocks are Hadean, and that's the clip play that pertains to signs of water chemistry, sheet tectonics and beingness that his colleagues are uncovering successful these aforesaid rocks. "That's wherefore the property of these rocks is truthful crucial."