The Earth’s geographic poles – the points where the imaginary axis of the planet’s rotation is located – may be far less immutable than previously known, with a new study finding that ancient sea-level changes provide a clue to their movement.

Earth has two main pairs of poles: its magnetic poles, resulting from its magnetic field, and its geographic poles based on its rotation. The magnetic poles are constantly in movement and are often hundreds of kilometres away from the geographic north and south poles. They can even flip altogether.

The geographic poles are much more stable. But they can move a little, through a phenomenon called true polar wander. This is driven by the way plate tectonics and mantle convection slowly redistribute mass in Earth’s mantle and affect the planet’s spin.

When the spin of the planet is thrown out of whack, the solid outer layers of the globe begin to move in order to help Earth find a new stable spin equilibrium. This has the effect of moving the geographic poles.

“The crust and the mantle effectively slip over the core during a true polar-wander event,” says at the University of Oslo in Norway.

However, until now much of the evidence for true polar-wandering events has come from ancient magnetic data locked inside rocks that formed millions of years ago, and this evidence has yielded confusing and conflicting results about the frequency and scale of the events.

So, Domeier and his team took a different approach. They analysed the geological record of sea-level change, looking for distinctive signals that might be expected during a true polar-wander event.

Because of the way ocean water can more quickly adjust to the centrifugal potential changes than the rocky sea floor, true polar-wander events are expected to leave a telltale pattern. Sea level will rise in one half of the northern hemisphere and fall in the other half, and it will also rise in one half of the southern hemisphere and fall in the other half.

The northern and southern hemisphere signals are reversed, however, so if it is the western side of the northern hemisphere that experiences sea-level rise, it will be the eastern side of the southern hemisphere that does so, too, creating a beach ball-like global pattern.

“This is a very strange pattern that is not caused by other Earth processes,” he says.

On the timescales we experience, the events would be unnoticeable. But over longer periods of geological time, a wandering pole changes the distribution of land and sea.

For instance, from their analysis of ancient sea-level patterns, Domeier and his colleagues discovered that the geographic poles moved dramatically, over periods of around 10 million years, four times in the geological past: at 20, 90, 140 and 190 million years ago.

“By the timescales of human experience, the movement may not seem fast,” says Domeier.  “We cannot estimate the exact speed, but we can recognise events where the rate of polar motion exceeded about 0.6 degrees per million years.”

He says this is faster than the rate at which most tectonic plates move – fast enough to potentially have an effect on climate systems.

What’s more, we know that true polar wandering continues today, although maybe not at the rate seen during the four fast bursts in the geological past.

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“[It] is measurable by satellites at a rate of about 10 cm per year, but most people are unaware of this. So these events are totally unrecognisable according to our everyday experience,” says Domeier.

at the University of Sydney says very few people are aware that Earth’s 2800-km-thick outer shell of the crust and mantle are in motion with respect to Earth’s spin axis.

The study demonstrates that clues in the coastline change provide an independent fingerprint of true polar wander.

“This is a very exciting development that helps us link very deep Earth processes to changes in long-term climate and sea level on the planet,” says Zahirovic.

The asteroid strike 66 million years ago caused a planetary-scale firestorm that burned dinosaurs to a crisp all over the world, according to simulations of the impact.

The so-called Chicxulub asteroid, which was 10 to 15 kilometres wide, landed in what is today the Gulf of Mexico at the end of the Cretaceous Period.

Until now, it has been thought that most of the worst effects of heat and fires would have been relatively regional, and global extinctions were mainly caused by a “nuclear winter”, where dust blocks out the sun causes dramatic cooling.

at Purdue University, Indiana, and his colleagues analysed geological observations and impact simulations in the laboratory, which showed around five times more material was vaporised by the strike than previously thought.

The new work suggests that in the aftermath of the impact, a plume of rock vapour was blasted tens of thousands of kilometres into space and ended up being distributed high above the entirety of the planet.

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“After the impactor first strikes the Earth, it only takes about a second for much of the kinetic energy to be converted to heat, vaporising over 1000 cubic kilometres of rock,” says Johnson. 

Just seconds later, the vapour plume expanded above much of Earth’s atmosphere into space, he says, leading to both dust and glassy, metallic beads called spherules, condensing from the vapour.

This immense vapour cloud ultimately turned into 1.6 trillion tonnes of dust, which blanketed the planet, sealing in heat, the study found. Meanwhile, the heavier spherules slammed back into the atmosphere.

“As this material re-enters the atmosphere over the coming hours, friction decelerates and heats the spherules, creating an approximately hour-long pulse of thermal radiation,” says Johnson.

“This would kill off creatures that were unable to shelter from it and was intense enough to ignite forest litter like grass and pine needles and may have even been enough to ignite trees.”

The geologic record suggests the ensuing fires may have lasted for years and would have been reminiscent of the bushfires currently gripping Europe, except on a global scale, he says.

“The Cretaceous animals would have received 17 times the dose of thermal radiation that is 100 per cent lethal to humans,” says Johnson. “That should be enough to kill off even thick-skinned dinosaurs.”

at the Queensland University of Technology in Australia says the study shows that the dust layer encircling the planet was essentially opaque to infrared and visible light, trapping the heat.

“Every joule of heat created by incoming spherules is turned into a thermal pulse that bakes the surface of the Earth,” says O’Neill. “For about 30 minutes, the land is turned into history’s largest barbecue.”

However, this isn’t the whole story, he says. For example, life in the oceans was also badly affected by the event, driving many marine animals such as mosasaurs and ammonites extinct. This is better explained by the effects of a nuclear winter blocking out the sun on photosynthesising organisms, rather than an atmospheric thermal pulse, says O’Neill.  

“We tend to think of mass extinction events as a murder mystery – if we can just find the murder weapon, we could solve the case. But mass extinctions seem more like a cascading system of failures,” he says.

A huge crater in Western Australia was created by an asteroid strike 3 billion years ago, according to a mineral-dating technique. This would make it the oldest impact crater on Earth – but other researchers have questioned its proposed age.

The North Pole Dome crater, also known as the Miralga impact structure, was first described by at Curtin University in Perth, Australia, and his colleagues in 2025. They estimated that it could be up to 100 kilometres wide.

Kirkland and his team found a layer of rock containing cone-shaped features called shatter cones, which form only after a high-impact event, such as an asteroid strike. Their original study didn’t directly date this rock, but based on correlations with dated rocks in the layers above and below, they proposed that the impact .

This would make it more than 1.2 billion years older than the Yarrabubba crater in the south of the state, which is regarded as the oldest reliably dated asteroid-strike crater on Earth.

It would also make it the only known impact from the Archaean aeon, a time when the entire planet was a giant but inhospitable water world.

However, another team, including , also at Curtin University, strongly contested the 3.47-billion-year date. Based on their own analysis of rocks in the area, the team members argue that the impact took place no earlier than .

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Now, Kirkland and his colleagues say they have successfully dated recrystallised minerals at the crater site, which contain shatter cones. “We have now actually looked inside the rocks and tried to find minerals that directly responded to impact in the rock itself, rather than making correlations,” says Kirkland.

Using the rate of the decay of uranium into lead, the team dated zircons within the shatter cones, which recrystallised as a result of the force of the asteroid strike.

They also dated the mineral apatite, which would have formed in the hydrothermal system created by the heat of the impact.

Both the apatite and the zircons returned dates of around 3.02 billion years old, says Kirkland. “So now we’ve got evidence for very hot water percolating through the rocks 3 billion years ago and also evidence for this really unusual heating and recrystallisation process,” he says.

Kirkland says no other known process, such as mountain building or regional metamorphism, easily explains the mineral changes inside the shocked rocks, because there is no evidence that the area was heated or deformed by those processes at about 3.02 billion years ago.

“The only process really that we can link to these mineralogical changes is an impact,” he says. “So that means the best evidence now is a 3-billion-year-old impact, and that by far is the oldest impact crater on the planet.”

Cavosie welcomes the fact that the age of the crater has been revised significantly, but he thinks Kirkland’s team is still overestimating the crater’s age.

“While I’m relieved these authors have backed off their 2025 ‘3.5-billion-year impact’ hypothesis, I don’t think they’ve presented a compelling case for a [3.02-billion-year] impact either,” says Cavosie. “The slow march of science towards the truth thus continues.”

Cavosie says there are clearly shatter cones in younger rocks that are only 2.77 billion years old, which means the impact must have happened after this date.

at Yale University, who was also part of the group that critiqued the original study, agrees with Cavosie that the rocks must be younger than 2.77 billion years.

“While the new study dismisses this observation because these rocks ‘have not been dated’, they are straightforwardly correlated to nearby rocks that have been dated,” says Brenner.

Kirkland says the key difference is that his team has now directly dated minerals inside the shocked rocks. “The younger age argument still depends on long-distance correlation of undated rocks, largely from satellite-based mapping rather than direct geochemistry or geochronology,” he says. “We now have two mineral clocks from the impact rocks themselves giving the same age. That is why direct dating matters.”

Around 15 minutes after the magnitude-9 Tohoku earthquake on 11 March 2011, almost the whole of Japan jumped half a centimetre to the east. This lurch resulted from an immensely powerful seismic wave that travelled 5800 kilometres to the planet’s core and then bounced back towards the surface.

In the context of the devastation caused by the earthquake, including localised land movements of many metres and 40-metre tsunami waves that led to the meltdown of three reactors at the Fukushima Daiichi nuclear plant, 5 millimetres may seem insignificant.

But this movement took place over a distance of 3000 kilometres, nearly seven times longer than the length of the earthquake’s main rupture line and longer than any slip ever recorded.

What also makes the case unusual is the timing and the pattern, says at the University of Chicago. “We see a small 5-millimetre eastward step that happens nearly simultaneously and with similar size across almost all of Japan, without any ordinary earthquake at that exact time.”

Not only was the shift immense in its north-south extent, but its width encompassed all of Japan and beyond, into the ocean.

“It is not just a narrow ‘edge’ that moved,” says Park. “The eastward step extends at least across the whole of Japan where we have GPS stations. If we had similarly dense instruments on the seafloor, we could say more precisely how far offshore this motion extends, but on land, the shift is observed pretty much everywhere across Japan.”

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By analysing extensive GPS and seismic data recorded during the catastrophe, Park and her colleagues have figured out how such a phenomenally vast movement was triggered and why the rupture took place 15 minutes after the main quake.

Earthquakes often generate waves that travel deep into Earth’s interior and reflect off the core, but they usually become quite weak by the time they have travelled to the planet’s centre and then back up.

In Tohoku’s case, the main shock was so large that the original wave, though weakened, remained powerful enough on its return to the surface to cause the nationwide lurch, as four adjoining tectonic plates moved in unison.

“We think the vigorous shaking from the original Tohoku earthquake might have already weakened the plate boundaries, making them more susceptible to be moved when the core-reflected wave came by,” says Park.

The event demonstrates there are previously unrecognised mechanisms of destruction that can follow earthquakes, says Park. “It shows that, after a big earthquake, we might also need to be aware of potential seismic hazards due to such deep-travelling wave arrivals that can trigger more events, and over very large distances.”

More research is now needed to understand the implications of this kind of movement for other parts of the world with similar faults, says at the University of Canterbury, New Zealand.

“It shows that large earthquakes can trigger widespread, delayed fault motion minutes later, and over much larger regions than expected,” says Lee.

The asteroid strike that wiped out the dinosaurs hit with such force that it took at least 8 million years for the impact site to cool down, creating a warm underground ecosystem where microscopic life thrived.

The Chicxulub asteroid, which collided with Earth 66 million years ago at what is now Mexico, is thought to have been as large as 15 kilometres in diameter. The strike caused so much climate chaos that it wiped out three-quarters of species on Earth. All the dinosaurs except the ancestors of birds became extinct and a nuclear winter gripped the planet for at least 15 years.

Its effects were also felt deep underground. “The Chicxulub impact was big enough to cause deformation at least 35 kilometres under the surface of the Earth, detectable using geophysical surveys,” says at the University of Glasgow, UK.

The impact melted about 10,000 cubic kilometres of rock, she says. The combination of melted rock and seawater created porous material filled with tiny pockets of hot water, known as a hydrothermal system.

Because of the presence of minerals that only form where there is liquid water and heat, we know that the asteroid would have created hydrothermal environments to depths of several kilometres. But the scale and lifespan of the heating and resulting hydrothermal system has, it seems, been massively underestimated.

Previously, it was thought it took only 2 million years for the impact site to cool down. Now, Pickersgill and her colleagues say it may have taken at least four times longer, giving hydrothermal life much more time to thrive.

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“One of the biggest unknowns about all impact-generated hydrothermal systems, and Chicxulub in particular, is how long the heat keeps water circulating through the structure,” says Pickersgill.

To figure this out, the team drilled 1 kilometre into the crater to obtain rock cores. Because potassium in the rocks has decayed into argon gas over time, the researchers could measure the amount of argon trapped in the samples to find out their age.

“We got a range of ages from the time of impact at 66 million years ago to about 58 million years ago,” says Pickersgill. “That told us that hydrothermal activity was ongoing in at least part of the Chicxulub structure for 8 million years after the impact.”

Sulphur isotopes in the cores provide evidence that microbial life existed in the hydrothermal system and recovered rapidly after the impact.

The results mean that the very earliest impact craters on the young Earth – and perhaps other worlds – may also have had habitable hydrothermal systems for longer than previously known.

“This provides more opportunity for life to develop, evolve and spread,” says Pickersgill. “It supports the concept that early life on Earth may have found a long-term home in impact craters, and possibly even life on other planets where these massive impact craters are dominant surface features.”

at Curtin University in Perth, Australia, says while there is “not an entirely unambiguous record of continuous hydrothermal activity” at Chicxulub, the evidence is strong that the impact site stayed hot for millions of years.

“Large impacts do not simply destroy environments,” he says. “They can also create long-lived underground systems where hot fluids circulate through shattered rock. These chemically rich settings may provide sheltered habitats for microbes and perhaps even favourable conditions for some of the early chemical steps towards life.”

The African continent may have begun tearing itself apart in a new location. Gases emerging from an arc of hot springs in Zambia appear to be coming from deep below Earth’s crust, in a sign that a new tectonic plate boundary could be opening up.

There are many rift valleys around the world where continents have been pulling apart for tens of millions of years, including the East African Rift valley, which runs from the Red Sea to Mozambique. Over millions of years, rifting can lead to a tectonic plate splitting in two, but it is unusual to find a site where this process may be just beginning, says at the University of Oxford.

The Kafue Rift in Zambia is part of a 2500-kilometre-long rift zone stretching from Tanzania to Namibia and possibly out into the Atlantic Ocean. Geologists think the area may be showing signs of being in the early stages of forming a new boundary between continental plates, because of the geography, low-gravity anomalies, high sub-surface temperatures and low-level seismicity. But, until now, there has been no geochemical evidence.

Karolytė and her colleagues have now analysed gas samples collected from five hot springs and three geothermal wells in central Zambia. The team found that helium and carbon isotope ratios in the gases are the same as those that exist deep beneath Earth’s crust, suggesting that fluids from the mantle, up to 190 kilometres below the springs, are making their way to the surface. This implies a tear in the region’s tectonic plates.

“What our data confirms is that this system is currently ‘awake’ and geologically active,” says Karolytė. “Having an active rift developing doesn’t necessarily mean that in 100 million years you’re going to have an ocean there. But it is a possibility.”

The earliest stages of continental rifting release gases that have accumulated in the rocks for millions of years. Among these is helium, a critical resource for high-tech industry and medicine. In the Kafue Rift, this process has created concentrations of helium of up to 2.3 per cent in the fluids reaching the surface – high enough that the region is already attracting interest from industry.

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“It’s hard to find these tectonic conditions that are just right to concentrate and release helium in a way that it can be captured,” says Karolytė.

at the University of Sydney, Australia, says, despite the absence of active volcanoes and significant seismicity, he agrees there are many signs in the region that the landscape is tectonically active.

The new geochemical evidence from the hot springs reveals that the Kafue Rift is an early-stage continental rift where mantle fluids rich in primordial helium-3 are rising through faults, he says. “It is reasonable to think that the Kafue Rift may evolve into a plate boundary sometime in the future.”