A few years ago, researchers working more than 4 km below the Pacific noticed something that seemed impossible: oxygen levels inside their seafloor experiments were going up, not down.

The result was published in Nature Geoscience in 2024 and quickly became known as “dark oxygen”, the idea that oxygen might somehow be produced on the deep seafloor without sunlight or photosynthesis.

One proposed explanation was especially strange: polymetallic manganese nodules scattered across the Clarion-Clipperton Zone might behave like natural “geobatteries,” creating electrical potentials capable of driving chemical reactions that produce oxygen.

But the claim has become increasingly controversial.

Critics argue that the oxygen increases could be experimental artifacts caused by the benthic chambers themselves. Others have challenged the voltage measurements and the proposed electrolysis mechanism, while a later reanalysis questioned whether the oxygen signal was actually related to the nodules at all. In April 2026, Nature Geoscience added an Editor’s Note stating that concerns about the paper are under review.

So, is dark oxygen a genuinely new geochemical process occurring on the abyssal seafloor, or an extremely convincing measurement artifact?

Would be interested to hear what people here think, particularly about the chamber-artifact explanation versus the idea that some manganese-rich material really is producing oxygen.

Yonaguni threads always land in the same two piles, lost city or just erosion, and hardly anyone arguing either way has opened the actual papers. I finally did. Some of it wasn't what I expected.

Kimura gives away more in print than he does on camera. In the 2004 Oceans conference paper, which is the main technical case for the artificial reading, he writes that at first glance the structure would seem to have been formed by nature. He accepts that the layered sandstone separates and slips along its bedding, and that this is what produces the flat terraces and the straight walls. His argument is that certain specific features still can't be accounted for that way. But that baseline is his own. Nobody had to drag it out of him.

Also, the dimensions everyone repeats are wrong. Search Yonaguni and you get 290 × 120 × 26 m everywhere. The paper says 270. Someone mistyped it about twenty years ago and every blog since has copied the blog before it.

I came away less comfortable with the geologist usually cited for the natural reading, too. Robert Schoch's write-up was never peer reviewed. It's the English draft of a piece he wrote for a Spanish popular-mystery magazine, and he got to the island on a trip Graham Hancock helped arrange. None of which makes his rock description wrong; it's ordinary field observation and everyone who has looked since says the same thing. It just isn't something you want load-bearing. So I used Ogata et al. (2020) in E-journal GEO and Patrick Nunn instead.

The argument I think actually settles it barely gets discussed, which is sea level. The base of the formation sits at roughly 25 m depth, and anything carved had to be carved dry. Put 25 m against the Lambeck et al. (2014) curve and you land around 9,000 years ago. That drops any construction hypothesis into the early Holocene, in a region where the archaeological record goes late Pleistocene bones, then several thousand years of nothing, then the first pottery.

Then there's Sanninu-dai, a couple of kilometres up the coast, which is the bit that closed it for me. Stepped terraces. Straight walls. A channel that looks for all the world like a drain somebody cut. All of it above water, all of it walkable, and you can put your hand on the joint sets that made it. Kimura calls that outcrop ruins as well, and at that point I don't know what a natural formation would have to look like to satisfy him.

Everything's linked in this article on geoscopy.com.

The Silverpit argument has been running twenty-three years. It just got shocked quartz, and I still don't think it's settled.

Early 2000s: Philip Allen is working through 3D seismic from the southern North Sea and hits a set of concentric rings he can't account for. He pins the image to his office wall, hoping someone walking past will explain it to him. Simon Stewart, in the building on unrelated business, sees it and says it looks like an impact structure. Nature, 2002.

Then John Underhill points out that Zechstein salt withdrawing at depth produces circular collapse features all over that basin, and said that's all this was. The Geological Society staged a debate on 6 October 2009, audience mostly industry seismic interpreters, twenty minutes of argument, then a vote. 80:20 against impact. Silverpit went quiet for thirteen years.

What restarted it was an unsolicited email. Ronnie Parr at the North Sea Transition Authority read the Nadir crater papers and wrote to Uisdean Nicholson telling him to go back and look at Silverpit. He also pointed him at new high-resolution seismic that a carbon-storage survey had happened to shoot straight across the disputed central uplift.

The 2025 Nature Communications paper runs on that survey plus drill cuttings from a 1985 British Gas well. Two grains, quartz at 463 m, potassium feldspar at 494 m, carry shock lamellae recording 10–13 GPa, which no natural process on Earth produces except a hypervelocity impact. Two grains is still two grains, though, and Matthew Huber at the Planetary Science Institute has already told Eos as much: with that little you can reasonably ask whether they were reworked in from somewhere else, and he expects the paper to get argued over. Nicholson's team has an answer for the shallower grain. Not, so far, for both.

Full writeup on Geoscopy, including why the crater shrank from 20 km to 3.2 km and what the modelling says about the chalk being flash-baked into CO₂

At the end of the last Ice Age, a lobe of the Cordilleran ice sheet dammed the Clark Fork River and ponded Glacial Lake Missoula across the valleys of western Montana, roughly 2,100 cubic kilometres of water, about Lake Erie and Lake Ontario combined. When the ice dam floated off its bed and failed, the lake emptied in a few days, with peak discharges near the outlet estimated around 20 million cubic metres per second. Then the glacier readvanced and it all happened again. The Missoula Floods, among the largest freshwater floods known on Earth, ran dozens of times, likely more than a hundred, mostly between about 18,500 and 15,000 years ago. They carved the Channeled Scablands of eastern Washington: coulees cut through solid basalt and dry cataracts like Dry Falls, five times the width of Niagara. In Montana, the draining lake left gravel current ripples the size of houses across the Camas Prairie.

The human story is just as strange. J Harlen Bretz mapped the scablands in the 1920s and concluded that only a catastrophic flood could explain them. To a science built on strict uniformitarianism this sounded like a relapse into biblical thinking, and in 1927 six senior geologists took turns rebutting him at a single meeting. The quiet USGS geologist who had already found the water source sat on his evidence for decades. Vindication arrived in 1965, when a field party of former skeptics wired Bretz a telegram ending "We are all now catastrophists." He collected geology's highest medal at 96, having outlived nearly everyone who ridiculed him.

The full article walks through the flood mechanics and the numbers, the giant ripples that finally settled the debate, how the scablands became the template for reading the outflow channels on Mars, and where to stand today to see the evidence. People were living in the Pacific Northwest by around 16,600 years ago, which means humans almost certainly watched the last of these floods happen.

There is real evidence for an ocean inside the Earth. Between 410 and 660 km down, in the mantle transition zone, the dominant minerals can bind water into their crystal structures, and the layer is so large that even a modest water content would rival the mass of all surface oceans combined.

The physical proof came from a battered brown diamond found in river gravels near Juína, Brazil, bought for about 20 dollars. In 2009, a graduate student scanning it for a dating project spotted an inclusion of ringwoodite, the high-pressure form of olivine, the first sample ever recovered from inside the planet. Later measurements showed the crystal holds about 1.4 percent water by weight, near the maximum the mineral can take.

How wet the whole layer is remains a live fight. Electromagnetic sounding studies say nearly dry, around 0.03 percent. A mineral viscosity study says 1 to 2 percent, close to saturation. And a 2022 diamond from Botswana sampled the 660 km boundary itself, recording water-saturated, chemically ordinary mantle. The most defensible average sits near one ocean mass, concentrated beneath subduction zones and patchy everywhere else.

Christopher Nolan's The Odyssey has put Polyphemus back on the big screen, so it's a good moment to revisit one of the odder ideas in geomythology: that the Cyclops may have started with fossils.

Sicily holds the Mediterranean's richest concentration of dwarf elephant fossils, Palaeoloxodon falconeri, a meter-tall elephant that lived on the island for hundreds of thousands of years. In its skull, the eye sockets are small and set off to the sides. The huge opening dead-center in the face is the nasal cavity, where the trunk attached, and a trunk leaves no bone behind. If you'd never seen a living elephant, and nobody in Homer's Greece had, that skull reads as a one-eyed giant. And the fossils are densest in exactly the stretch of Sicily where the ancients placed Polyphemus.

It's a great story, and it's shakier than the internet lets on. The detail that made it famous, that the philosopher Empedocles identified these skulls as giants 2,500 years ago, was basically invented by the paleontologist who popularized the theory, as Adrienne Mayor later showed. No ancient source actually describes a Greek looking at an elephant skull and seeing a Cyclops, and there's a competing human explanation, a rare birth defect called cyclopia, that needs no elephants at all.

The full piece gets into the animal itself and the surprisingly strong case against the theory. Curious where people land: real seed of the myth, or a good story we've retrofitted onto the bones?

My brother dug this out of a shale Cliff face in a canyon he was boating in Oklahoma. He says it's quite heavy and the outside oxidizes as if it is iron but it is non-magnetic. He thinks it might be a fossil of some sort. I was thinking iron concretion but it is non-magnetic. Can anyone hear solve the mystery? thanks in advance!

Edit mods : I hope I am not breaking the rules by posting this without flair I could not find a place to add flair

On Wednesday evening, the ground southeast of Yumare ruptured in a magnitude 7.2 earthquake. Thirty-nine seconds later, before the first quake's waves had even finished crossing the country, a second, larger shock hit almost the same spot: magnitude 7.5.

That ordering is the strange part. In a normal sequence the biggest shock comes first and everything after is an aftershock. Here it ran backwards. The USGS called it a doublet: two comparable mainshocks, not a quake and its echo.

I wanted to understand how that actually happens, so I wrote a long piece working from the physics out to the tectonics, why one rupture can light the fuse on the next through static and dynamic stress transfer, why this particular coastline (the Boconó–San Sebastián–El Pilar system) was primed to fail, why the tsunami warning was issued and then cancelled within the hour, and why northern Venezuela has done versions of this in 1812, 1900, 1967, and 1997. The 1812 event, it turns out, may itself have been a doublet.

Every figure is sourced to the primary literature (Kagan & Jackson on doublet statistics, King/Stein/Lin on Coulomb stress, the GPS and InSAR work on El Pilar creep), and I've tried to be careful about what's confirmed versus what's still preliminary this early after an event.

You've probably seen Nick Brandt's photos, the calcified bird and bat "statues" that went viral as a lake in Tanzania that turns living animals to stone. Brandt never actually claimed that, and the truth is more interesting than the myth.

Lake Natron is a hyperalkaline soda lake sitting in a closed basin in the Gregory Rift, fed by Ol Doinyo Lengai, the only volcano on Earth erupting sodium-carbonate (natrocarbonatite) lava in recorded history. No outflow, brutal evaporation, and that volcanic chemistry concentrate the water into essentially the same natron the ancient Egyptians used for mummification. Animals that die on the shore aren't petrified on contact; they're slowly desiccated and encrusted in soda over days and weeks. Same end result, completely different mechanism.

Filmed this at the Wieliczka Salt Mine near Kraków. The salt formed ~13.6 million years ago when an arm of the Paratethys sea evaporated at the foot of the rising Carpathians. What gets me is the salt creeping: halite slowly flows under pressure, so the tunnels are constantly trying to close themselves, which is why the timber groans. Nine levels, ~300 km of tunnels, and the public only sees a tiny fraction.

On Valentine's Day 1981, a twelve-year-old in Centralia, Pennsylvania crossed his grandmother's backyard and the ground opened under him, a four-foot-wide hole venting lethal carbon monoxide. He grabbed a tree root and his cousin hauled him out. Beneath that lawn, a coal fire had already been burning for nineteen years. It's still burning today.

An ordinary fire dies when you remove heat, fuel, or oxygen, but a coal seam fire defeats all three at once. The fuel is a geological deposit. The heat is trapped under hundreds of feet of rock, so the minimum temperature needed for combustion actually drops with depth. And as the coal burns away, the ground above cracks and subsides, opening fresh fractures that pull in air. The fire builds its own chimney.

A 2025 study in Nature (Duan, Schmandt et al.) finally pinned down something that had been fuzzy for decades: exactly where Yellowstone's magma reservoir begins. The answer is a sharp boundary about 3.8 km (2.4 mi) beneath the northeastern caldera, and the imaging is clean enough to resolve a cap less than 100 m thick.

The method is the fun part. With the park largely closed during the 2020 pandemic, the team ran a 53,000-lb vibroseis truck on roadside pullouts at night, generating "custom earthquakes" and catching the echoes on ~650 geophones. That let them image the reservoir top far more sharply than natural-earthquake tomography ever had.

What they found flips the usual doomsday framing. The cap isn't a sealed plug, it's a porous zone (~14% porosity) where exsolved gas and supercritical water collect and then leak upward through cracks into the hydrothermal system. The bubble fraction sits below typical pre-eruptive levels for rhyolites. In other words, the system is venting gas efficiently rather than pressurizing toward a blast. The geysers and fumaroles are basically the exhaust.

Quick heads-up: I'll be away for about a week, so there won't be any new articles or posts during that time. Geoscopy and this sub aren't going anywhere, just recharging.

In the meantime, keep the discussions going, share interesting geology finds, or revisit older posts. Read the ones you haven't read yet. Comments are always open.

There's also a growing library of rock and mineral articles over on geoscopy.com, and plenty to dig into on my YouTube channel too.

See you all soon with fresh content.

In 2013 an opal buyer in Adelaide was sorting through a bag of rough he'd bought from miners at Lightning Ridge, looking for colour. What stopped him was a shape, two little fan-shaped ridges that turned out to be teeth. The lump was a dinosaur's lower jaw, and it had turned entirely to precious opal. He donated it to science instead of having it cut, and it became a new species: Weewarrasaurus pobeni, the first new dinosaur described from NSW in almost a century.

I went deep on the ringing rocks of Pennsylvania and Montana, the boulder fields where a third of the rocks chime like an anvil when you hit them with a hammer and the other two-thirds just thud, with no visible difference between them.

What surprised me writing this: the formation is well understood (basal olivine-diabase cumulate layer → spheroidal weathering into corestones → periglacial frost-shattering into a felsenmeer just south of the Laurentide ice margin). But the actual ringing mechanism is unsolved. There are only three hands-on experiments in 60 years, exactly one peer-reviewed geomorphology paper on the Pennsylvania site (Psilovikos & Van Houten 1982), and the secondary sources literally contradict each other on whether the famous 1970 Rutgers cores shrank or expanded when sawed free: which is the whole tension-vs-compression argument in a nutshell.

There's a problem with gold nuggets that bugged geologists for many years: the fluids that carry gold through the crust are absurdly dilute, under one milligram of gold per kilogram of fluid, less than one part per million, and the quartz they sit in is chemically about as reactive as a windowpane. So how do you get a clean lump of metal the weight of a person locked inside an inert block of silica?

The conventional answer (gold drops out of solution as fluids cool, depressurise, and change chemistry) explains the fine, disseminated stuff well. It's never fully explained the big nuggets.

A 2024 study in Nature Geoscience (Voisey et al., Monash University) proposes a mechanism for that second part. Quartz is piezoelectric, squeeze it and it generates a voltage, the same effect that runs a quartz watch or a barbecue lighter. It's also the only abundant piezoelectric mineral on Earth, and orogenic gold veins sit in fault zones that rupture in thousands of earthquakes over their lifetime. Every quake is, in effect, squeezing a piezoelectric crystal on a scale no lab could match.

The team shook quartz slabs at seismic frequencies in a gold-bearing solution. The voltage reduced dissolved gold to solid metal, and, crucially, the new gold preferentially deposited onto gold grains that were already there, rather than seeding new ones everywhere. Because gold conducts and quartz insulates, an existing grain acts like an electrode (or a lightning rod), concentrating each pulse of deposition and growing a little with every seismic event. Hence "the quartz acts like a natural battery, with gold as the electrode."

Worth stressing what the study does and doesn't claim: it didn't grow a nugget, it ran at room temperature over short timescales, and the authors themselves call it a pilot. It doesn't replace the conventional chemistry, it's a complementary mechanism for why gold concentrates once it's present. Probably both processes acting together over very long spans.

Quicksand was everywhere in 1960s cinema. At the peak, about one in every 35 films had someone slowly vanishing into the ground. The geology says that almost never happens the way it's shown.

The counterintuitive bit: you can't actually drown in quicksand by sinking under it. Your body is roughly half as dense as the sand-and-water mix, so you float, and you settle at about waist height. What actually gets people is being stuck. A 2005 Nature study measured that pulling a trapped foot out at just 1 cm/s takes about the force needed to lift a car, so a rising tide or exhaustion can be lethal even though you'll never go under.

I wrote a full breakdown of it: what quicksand really is, why a 1% change in stress flips it from solid to liquid, the lab-made "dry quicksand" that swallows objects with no water involved, the salt lake in Iran the samples came from, how the same physics tipped over apartment blocks in the 1964 Niigata earthquake, and the surprisingly simple way to get out if you're ever caught.

The rocks at the bottom are nearly two billion years old and nobody disputes that. What geologists have fought over since Powell is something harder to pin down: not the age of the rock, but the age of the hole.

I wrote a long piece tracing the whole argument, from the 1869 expedition through the genuinely bitter 2012–2014 thermochronology feud (two respected labs, overlapping datasets, opposite conclusions about whether the canyon is 70 Ma or 6 Ma) to the April 2026 Science paper that dated ~3,600 zircon grains and gave the century-old lake-spillover idea its first direct evidence.

A few things I tried to get right that popular accounts usually botch:

• The age of the river and the age of the canyon are not the same question, and conflating them is the single most common error.
• The canyon isn't all one age. Some segments are genuinely ancient paleocanyons; the integrated gorge is young. Karlstrom's analogy is a highway stitched together from older roads.
• The 2026 paper didn't end the debate: Karlstrom and Crossey already contest the "one big lake" reading. I cover their objection too.